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Biogenic volatile organic compound emissions from nine tree species used in an urban tree-planting program
Abstract
The biogenic volatile organic compound (BVOC) emissions of nine urban tree species were studied to assess the air quality impacts from planting a large quantity of these trees in the City and County of Denver, Colorado, through the Mile High Million tree-planting initiative. The deciduous tree species studied were Sugar maple, Ohio buckeye, northern hackberry, Turkish hazelnut, London planetree, American basswood, Littleleaf linden, Valley Forge elm, and Japanese zelkova. These tree species were selected using the i-Tree Species Selector (itreetools.org). BVOC emissions from the selected tree species were investigated to evaluate the Species Selector data under the Colorado climate and environmental growing conditions. Individual tree species were subjected to branch enclosure experiments in which foliar emissions of BVOC were collected onto solid adsorbent cartridges. The cartridge samples were analyzed for monoterpenes (MT), sesquiterpenes (SQT), and other C-10-C-15 BVOC using thermal desorption-gas chromatography-flame ionization detection/mass spectroscopy (GC-FID/MS). Individual compounds and their emission rates (ER) were identified. MT were observed in all tree species, exhibiting the following total MT basal emission rates (BER; with a 1-sigma lower bound, upper bound uncertainty window): Sugar maple, 0.07 (0.02, 0.11) mu g g(-1) h(-1); London planetree, 0.15 (0.02, 0.27) mu g g(-1) h(-1); northern hackberry, 0.33 (0.09, 0.57) mu g g(-1) h(-1); Japanese zelkova, 0.42 (0.26, 0.58) mu g g(-1) h(-1); Littleleaf linden, 0.71 (0.33, 1.09) mu g g(-1) h(-1); Valley Forge elm, 0.96 (0.01, 1.92) mu g g(-1) h(-1); Turkish hazelnut, 1.30 (0.32, 2.23) mu g g(-1) h(-1); American basswood, 1.50 (0.40, 2.70) mu g g(-1) h(-1); and Ohio buckeye, 6.61 (1.76, 11.47) mu g g(-1) h(-1). SQT emissions were seen in five tree species with total SQT BER of: London planetree, 0.11 (0.01, 0.20) mu g g(-1) h(-1); Japanese zelkova, 0.11 (0.05, 0.16) mu g g(-1) h(-1); Littleleaf linden, 0.13 (0.06, 0.21) mu g g(-1) h(-1); northern hackberry, 0.20 (0.11, 0.30) mu g g(-1) h(-1); and Ohio buckeye, 0.44 (0.06, 0.83) mu g g(-1) h(-1). The following trees exhibited emissions of other C-10-C-15 volatile organic compounds (VOC): Littleleaf linden, 0.15 (0.10, 0.20) mu g g(-1) h(-1); Ohio buckeye, 0.39 (0.14, 0.65) mu g g(-1) h(-1); and Turkish hazelnut, 0.72 (0.49, 0.95) mu g g(-1) h(-1). All tree species studied in this experiment were confirmed to be low isoprene emitters. Compared to many other potential urban tree species, the selected trees can be considered low to moderate BVOC emitters under Colorado growing conditions, with total emission rates one-tenth to one-hundredth the rates of potential high-BVOC emitting trees. The emissions data were used to estimate the impact of this targeted tree planting on the urban BVOC flux and atmospheric VOC burden. Selecting the low-emitting tree species over known high BVOC emitters is equivalent to avoiding VOC emissions from nearly 500,000 cars from the inner city traffic.
... Plants, as sessile organisms, use such compounds to defend themselves against pathogens, herbivores, and other stress factors. Typically, these are compounds of low molecular weight, including isoterpenes, monoterpenes, sesquiterpenes, and other C10-C15 chemical structures (Curtis et al., 2014). BVOCs are easily released to the atmosphere in gaseous form, and in the presence of NOx and light, they contribute to photochemical reactions involved in the formation of secondary pollutants. ...
... e low BVOC emitting group of plants includes genera such as Malus, Camphora, Citrus, and Pyrus and species such as Ginkgo biloba and Juglans nigra. High-emitting BVOC plants belong to the following genera: Salix, Quercus, Populus, Pinus, and Liquidambar (Calfapietra et al., 2013;Curtis et al., 2014). ...
A large part of the civilizational progress has been achieved at the expense of the natural environment, which recently reached the stages that threaten its creator. Plants play an important role in various areas of our lives, and it turned out that we can rely on them to reduce this threat. The ability of living organisms and the systems they create to protect and restore the environment is at the core of a technology called environmental biotechnology. Advances in science and technology have created a plant-based discipline known as phytoremediation. This technology allows us to remove or reduce the level of pollutants in our surroundings. We can phytoextract heavy metals from contaminated soil and water with the help of resistant plant species and recover noble metals and rare elements. When the soil or water is contaminated with organic compounds, we try to eliminate them completely with the help of plants and their microbiome. Phytoextraction from water is related to the accumulation of pollutants in water and sediments, in which macrophytes from all water groups participate, including free-floating submerged and emerged plants. The task of these plants, apart from the accumulation of metals or organic toxins, is also the uptake of phosphorus and nitrogen to prevent the eutrophication of water. In recent years, the quality of air has deteriorated. Nowadays, 90% of the population breathes air that does not meet WHO standards. It should be emphasized that in the case of outdoor air, there is no industrial system for removing pollutants. In fact, we can only count on nature: rainfall and plants. Indoor air is sometimes even more polluted than outside and, therefore, we should be safe in it with the help of plants that are able to create a refuge. Additionally, it fulfills biofilling desires and improves our mood.
... BVOCs, respectively (Trapp et al., 2001;Guenther et al., 2012). BVOCs are also emitted in significant quantities by vegetation, such as street trees and urban forests, that are planted to improve the urban environment and provide a relaxing atmosphere for people living in urban areas (Matsunaga et al., 2017;Weber et al., 2014;Curtis et al., 2014;Lim et al., 2008). Thus, more attention is being given to BVOC emissions from urban areas because these compounds can efficiently react with NO X emitted by automobiles on nearby roads to produce O 3 (Prendrez et al., 2013). ...
... The results of other studies also showed that the standard emission rates (ERs) of isoprene emitted from Ginkgo biloba are quite insignificant (e.g., Guenther et al. (1994): <100 ng gdw − 1 hr − 1 ; Kesselmeier and Staudt (1999): negligible or no isoprene emission, or < 1000 ng gdw − 1 hr − 1 ; Xiaoshan et al. (2000): <100 ng gdw − 1 hr − 1 ). Another study on Zelkova serrata reported the emission of trace amounts of isoprene (<10 ng gdw − 1 hr − 1 (ERs) and monoterpene (420 ng gdw − 1 hr − 1 (ERs) (Curtis et al., 2014). Therefore, the isoprene emission pattern according to species (i.e., Zelkova serrata and Ginkgo biloba) in this study was similar to that seen in previous studies. ...
Emission characteristics of biogenic volatile organic compounds (BVOCs) (such as isoprene and monoterpenes) emitted from major species of street trees and urban forests by variations in temperature and photosynthetically active radiation (PAR) were investigated. The isoprene and monoterpene emission rates from Prunus sargentii, Ginkgo biloba, Zelkova serrata and Taxus cuspidata were meager. In contrast, the isoprene and monoterpene emission rates from Metasequoia glyptostroboides were very high. In particular, the emission of α-pinene from Metasequoia glyptostroboides was over 10,000 times higher than that from Ginkgo biloba. The patterns of isoprene emissions from the four tree species except for Metasequoia glyptostroboides concerning temperature and PAR were difficult to determine because the emission rate is very low. However, monoterpene emissions from all five tree species were clearly affected by temperature and PAR. These results showed that the characteristics of isoprene and monoterpene emissions differed depending on the tree species. Regarding monoterpene composition, α-pinene (81.3%) accounts for the majority of total monoterpenes from Metasequoia glyptostroboides. This could be a critical consideration when planting trees in an urban forest because BVOC emissions (e.g., α-pinene) have been well known to affect ground-level ozone formation rate via photochemical reaction with NOX. Since Metasequoia glyptostroboides showed relatively high BVOC emissions, the use of this type of tree in an urban forest with relatively high nitrogen oxide emissions should be carefully considered.
... Non-infected A. glutinosa and T. cordata were both minor constitutive isoprene emitters with trace-level isoprene emissions observed from non-infected leaves, con rming previous observations (Aydin et al. 2014, Curtis et al. 2014. In addition, both species emitted monoterpenes constitutively at a low level of ∼0.04 nmol m −2 s −1 and minor emissions of benzenoids and oxygenated volatiles were also observed in both species (Table 2). ...
... In addition, both species emitted monoterpenes constitutively at a low level of ∼0.04 nmol m −2 s −1 and minor emissions of benzenoids and oxygenated volatiles were also observed in both species (Table 2). Such low-level monoterpene emissions have been previously observed in the emissions of both species (Copolovici et al. 2011, Curtis et al. 2014). In addition, Tree Physiology Volume 00, 2021 Downloaded from https://academic.oup.com/treephys/advance-article/doi/10.1093/treephys/tpaa173/6046619 by Nanjing Agricultural University user on 06 May 2021 even under non-stressed conditions, most plants release tracelevel oxygenated volatiles, including long-chained aldehydes and alcohols (e.g., Copolovici et al. 2011, Jiang et al. 2018, Turan et al. 2019. ...
Highly host-specific eriophyoid gall- and erineum-forming mites infest a limited range of broadleaf species, with the mites from the genus Eriophyes particularly widespread on Alnus spp. and Tilia spp. Once infected, the infections can be massive, covering a large part of leaf area and spreading through the plant canopy, but the effects of Eriophyes mite gall formation on the performance of host leaves are poorly understood. We studied the influence of three frequent Eriophyes infections, E. inangulis gall-forming mites on A. glutinosa, and E. tiliae gall-forming and E. exilis erineum-forming mites on T. cordata, on foliage morphology, chemistry, photosynthetic characteristics and constitutive and induced volatile emissions. For all types of infections, leaf dry mass per unit area (MA), net assimilation rate per area (An), and stomatal conductance (Gs) strongly decreased with increasing severity of infection. Mite infections resulted in enhancement or elicitation of emissions of fatty acid derived volatiles, isoprene, benzenoids and carotenoid breakdown products in infection severity-dependent manner for all different infections. Monoterpene emissions were strongly elicited in T. cordata mite infections, but these emissions were suppressed in E. inangulis-infected A. glutinosa. Although the overall level of mite-induced emissions was surprisingly low, these results highlight the uniqueness of the volatile profiles and offer opportunities for using volatile fingerprints and overall emission rates to diagnose infections by Eriophyes gall- and erineum-forming mites on temperate trees and assess their impact on the physiology of the affected trees.
... Mavroidis and Ilia [33] prove the dependency of ozone level on NO 2 and NO concentrations with observations and Kesselmeier et al. (1995) [67] highlights tree-type-dependent emission of isoprene. Ozone production rates significantly increase with increased isoprene emissions, which are modified mostly by photosynthetically active radiation and temperature [68]. Observations from Starn et al. (1998) [69] show some evidence that elevated NO x concentration in the vicinity of trees can accelerate isoprene oxidation and concomitant O 3 production. ...
... Mavroidis and Ilia [33] prove the dependency of ozone level on NO2 and NO concentrations with observations and Kesselmeier et al. (1995) [67] highlights tree-type-dependent emission of isoprene. Ozone production rates significantly increase with increased isoprene emissions, which are modified mostly by photosynthetically active radiation and temperature [68]. Observations from Starn et al. (1998) [69] show some evidence that elevated NOx concentration in the vicinity of trees can accelerate isoprene oxidation and concomitant O3 production. ...
Climate sensitive urban planning involves the implementation of green infrastructure as one measure to mitigate excessive heat in urban areas. Depending on thermal conditions, certain trees tend to emit more biogenic volatile organic compounds, which act as precursors for ozone formation, thus hampering air quality. Combining a theoretical approach from a box model analysis and microscale modeling from the microclimate model ENVI-met, we analyze this relationship for a selected region in Germany and provide the link to air quality prediction and climate sensitive urban planning. A box model study was conducted, indicating higher ozone levels with higher isoprene concentration, especially in NO-saturated atmospheres. ENVI-met sensitivity studies showed that different urban layouts strongly determine local isoprene emissions of vegetation, with leaf temperature, rather than photosynthetic active radiation, being the dominant factor. The impact of isoprene emission on the ozone in complex urban environments was simulated for an urban area for a hot summer day with and without isoprene. A large isoprene-induced relative ozone increase was found over the whole model area. On selected hot spots we find a clear relationship between urban layout, proximity to NOx emitters, tree-species-dependent isoprene emission capacity, and increases in ozone concentration, rising up to 500% locally.
... Plants as sessile organisms use such compounds to defend themselves against pathogens, herbivores and other stress factors. Typically, these are compounds of low molecular weight, including isoprenes, monoterpenes, sesquiterpenes and other C10eC15 chemical structures (Curtis, Helming, Baroch, Daly, & Davis, 2014). BVOCs are easily released to the atmosphere in gaseous form, and in the presence of NO x and light, they contribute to photochemical reactions involved in the formation of secondary pollutants. ...
... The low BVOC emitting group of plants includes genera such as Malus, Camphora, Citrus, Pyrus and species as Ginkgo biloba and Juglans nigra. High-emitting BVOC plants belong the following genera: Salix, Quercus, Populus, Pinus and Liqidamber (Benjamin & Winer, 1998;Calfapietra et al., 2013;Curtis et al., 2014;Karl, Guenther, Koble, Leip, & Seufert, 2009). ...
Air pollution has become a global problem and affects nearly all of us. Most of the pollution is of anthropogenic origin and therefore we are obliged to improve this situation. In solving this problem basically our only partners are plants with their enormous biologically active surface area. Plants themselves are also victims of air pollution but because they are sedentary they developed very efficient defence mechanisms, which can also be exploited to improve the humanosphere. For their life processes plants require intensive gas exchange, during which air contaminants are accumulated on leaf surfaces or absorbed into the tissues. Some of the pollutants are included by plants in their own metabolism while others are sequestered. In some plant species, the processes of removing pollutants from the air is conducted in a very efficient way and therefore they are used in the environmental friendly biotechnology called phytoremediation. For urban areas, outdoor phytoremediation is recommended while indoor phytoremediation can be applied in our homes and workplaces. Because in near future purifying outdoor air to protect human health and well-being does not look the most promising, an important and increasing role will be played by indoor phytoremediation.
... Plants as sessile organisms use such compounds to defend themselves against pathogens, herbivores and other stress factors. Typically, these are compounds of low molecular weight, including isoprenes, monoterpenes, sesquiterpenes and other C10eC15 chemical structures (Curtis, Helming, Baroch, Daly, & Davis, 2014). BVOCs are easily released to the atmosphere in gaseous form, and in the presence of NO x and light, they contribute to photochemical reactions involved in the formation of secondary pollutants. ...
... The low BVOC emitting group of plants includes genera such as Malus, Camphora, Citrus, Pyrus and species as Ginkgo biloba and Juglans nigra. High-emitting BVOC plants belong the following genera: Salix, Quercus, Populus, Pinus and Liqidamber (Benjamin & Winer, 1998;Calfapietra et al., 2013;Curtis et al., 2014;Karl, Guenther, Koble, Leip, & Seufert, 2009). ...
Air pollution presently is a challenge fo-r many areas of the world. Plants are higher organisms that can best deal with this problem despite the fact often in the air is a mixture of pollutants of different origin and toxicity. The world of plants is very diverse and well adopted to changes in the environment, including air. This large biodiversity allowed to select species with a very high tolerance, which are the base for the discipline known as phytoremediation. All plants during their presence in the environment run the process of phytoremediation, but some species tolerate a very high concentration of selected pollutants. Moreover, they are able to uptake/accumulate and next to degrade/detoxify in order to make them less harmful. Tolerant plant species can be found in very extreme conditions but for phytoremediation are useful plant species which besides being cultivatable, produce a large leaf area and biomass. Urban areas often contribute in creating high polluted sites as street canyons, road crossing, bus stops, and surrounding of heavy traffic freeway. In all these places, air pollution can be mitigated by the presence of selected plant species. Additionally, agronomic practices allow to maintain them on a polluted site and to form them in configuration for optimal deposition of pollutants. Air phytoremediation in urban areas, where at present men spend most of the time, is strongly desired and hard to overestimate if environment and human health and well-being are the prospect.
... Plants as sessile organisms use such compounds to defend themselves against pathogens, herbivores and other stress factors. Typically, these are compounds of low molecular weight, including isoprenes, monoterpenes, sesquiterpenes and other C10eC15 chemical structures (Curtis, Helming, Baroch, Daly, & Davis, 2014). BVOCs are easily released to the atmosphere in gaseous form, and in the presence of NO x and light, they contribute to photochemical reactions involved in the formation of secondary pollutants. ...
... The low BVOC emitting group of plants includes genera such as Malus, Camphora, Citrus, Pyrus and species as Ginkgo biloba and Juglans nigra. High-emitting BVOC plants belong the following genera: Salix, Quercus, Populus, Pinus and Liqidamber (Benjamin & Winer, 1998;Calfapietra et al., 2013;Curtis et al., 2014;Karl, Guenther, Koble, Leip, & Seufert, 2009). ...
Air pollution has become a global problem and affects nearly all of us. Most of the pollution is of anthropogenic origin and therefore we are obliged to improve this situation. In solving this problem basically our only partners are plants with their enormous biologically active surface area. Plants themselves are also victims of air pollution but because they are sedentary they developed very efficient defence mechanisms, which can also be exploited to improve the humanosphere. For their life processes plants require intensive gas exchange, during which air contaminants are accumulated on leaf surfaces or absorbed into the tissues. Some of the pollutants are included by plants in their own metabolism while others are sequestered. In some plant species, the processes of removing pollutants from the air is conducted in a very efficient way and therefore they are used in the environmental friendly biotechnology called phytoremediation. For urban areas, outdoor phytoremediation is recommended while indoor phytoremediation can be applied in our homes and workplaces. Because in near future purifying outdoor air to protect human health and well-being does not look the most promising, an important and increasing role will be played by indoor phytoremediation.
... Plants as sessile organisms use such compounds to defend themselves against pathogens, herbivores and other stress factors. Typically, these are compounds of low molecular weight, including isoprenes, monoterpenes, sesquiterpenes and other C10eC15 chemical structures (Curtis, Helming, Baroch, Daly, & Davis, 2014). BVOCs are easily released to the atmosphere in gaseous form, and in the presence of NO x and light, they contribute to photochemical reactions involved in the formation of secondary pollutants. ...
... The low BVOC emitting group of plants includes genera such as Malus, Camphora, Citrus, Pyrus and species as Ginkgo biloba and Juglans nigra. High-emitting BVOC plants belong the following genera: Salix, Quercus, Populus, Pinus and Liqidamber (Benjamin & Winer, 1998;Calfapietra et al., 2013;Curtis et al., 2014;Karl, Guenther, Koble, Leip, & Seufert, 2009). ...
... Previous studies indicated that it is possible to mitigate emissions of air pollutants in urban areas by optimizing tree species selection (Ren et al., 2017). However, in-situ observations of ISOP emissions from urban tree species are still very limited, especially in over-expanding megacities with many local species (Curtis et al., 2014;Ghirardo et al., 2016;Jing et al., 2020;Yuan et al., 2020). This is particularly important in a country like China where cities are distributed across very large areas, and urban vegetation varies greatly from city to city (Bao et al., 2023). ...
... For example, the UHI could lead to (drought) stress and consequent changes in the emission of biogenic volatile organic compounds (BVOC) in trees (Niinemets, 2010;Calfapietra et al., 2015;Seco et al., 2015). Considering species' VOC emission potential thus becomes increasingly important for urban forest managers to avoid a negative effect of trees on the city's air quality (Calfapietra et al., 2013;Curtis et al., 2014). Additionally, the UHI could amplify climate change effects (Esperon-Rodriguez et al., 2020;Hirons et al., 2021). ...
The urban heat island (UHI) causes strong warming of cities and their urban forests worldwide. Especially urban forest edges are strongly exposed to the UHI effect, which could impact urban forest biodiversity and functioning. However, it is not known to what extent the UHI effect alters edge-to-interior microclimatic gradients within urban forests and whether this depends on the forests' structure. Here we quantified gradients of air temperature, relative air humidity and vapour pressure deficits (VPD) along urban forest edge-to-interior transects with contrasting stand structures in six major cities across Europe. We performed continuous hourly microclimate measurements for two consecutive years and analysed the magnitude and depth of edge effects, as well as forest structural drivers of microclimatic variation. Compared to edge studies in rural temperate forests, we found that edge effects reached deeper into urban forests, at least up to 50 m. Throughout the year, urban forest edges were warmer and drier compared to forest interiors, with the largest differences occurring during summer and daytime. Not only maximum, but also mean and minimum temperatures were higher at the urban forest edge up to large edge distances (at least 85 m). Denser forests with a higher plant area index buffered high air temperatures and VPDs from spring to autumn. We conclude that urban forest edges are unique ecotones with specific microclimates shaped by the UHI effect. Both forest edges and interiors showed increased buffering capacities with higher forest canopy density. We advocate for the conservation and expansion of urban forests which can buffer increasingly frequent and intense climate extremes. To this end, urban forest managers are encouraged to aim for multi-layered dense forest canopies and consider edge buffer zones of at least 50 m wide.
... The leaf at different ages has different VOCs emission. Although many studies have been conducted on VOCs emission from mature leaves of plants [19][20][21], there are relatively few studies on plant foliage at different ages. In addition, most of the studied plants were trees and crops, and there were few studies for shrubs. ...
Volatile organic compounds (VOCs) emitted by plant foliage play an important role in ozone (O3) and secondary organic aerosol (SOA) formation. Their emissions can be influenced by the leaf age. We explored the VOCs emissions and their effects on the formation of O3 and SOA from plant foliage in different ages. VOCs emissions from the young, mature, and senescent leaves of Ginkgo biloba, Ligustrum lucidum, and Forsythia suspensa were measured using the dynamic enclosure system and the TD–GC–MS technique. Based on the emission rates of quantified compounds, their potential to form O3 and SOA was estimated. Results showed that there were significant differences in the VOCs emission rate and their composition among leaves in different ages. The emission rate of the total VOCs by young leaves was the highest, while the lowest by senescent leaves. Monoterpenes were the dominant VOCs category, and isoprene emission had the lowest contribution for the leaves at each age. With increasing leaf age, the proportion of monoterpenes emission increased, and the proportion of sesquiterpenes decreased. The variations of isoprene and other VOCs were different. The potentials of total VOCs, isoprene, monoterpenes, sesquiterpenes, and other VOCs to form O3 (OFP) and SOA (SOAP) varied significantly among leaves at different ages. The total OFP and SOAP were the highest by young leaves, while the lowest by senescent leaves. With increasing leaf age, the contribution of monoterpenes to OFP and SOAP also increased, while that of sesquiterpenes decreased. Our study will provide support for the more accurate parameterization of the emission model and help to understand the VOCs emissions and study the precise prevention and control of complex air pollution at different times.
... Thus vegetation with proper design of plants can be used to improve the air quality of city areas which was accepted in many developed countries (Singh et al., 2019). However not all plants give benefits to reduce air pollutant some of the plants may act as pollutant itself by producing volatile organic compounds in the air (Curtis et al., 2014). Therefore the plants are carefully selected for vegetation traffic barrier (Shrestha et al., 2021). ...
Plants can be used to mitigate increasing air pollution from vehicular exhaust by planting them along roadside. The present study focuses on the changes on physiological parameters selected tree species growing along road passing through Kalupur fruit market and Vimal Park society, Ahmedabad, Gujarat. The leaf samples of four trees were collected observe some physiological and biochemical parameters including pH of the leaf extract, Relative Water Content, Stomatal index, and Total Chlorophyll. Result of study showed that Ficus religiosa has the highest pH of leaf extract at polluted site, Azadirachta indica has highest total chlorophyll compared to non-polluted and Polyalthia longifolia has highest Stomatal index and RWC.
... Municipalities frequently overlook species selection during large-scale tree-planting projects (Churkina et al. 2015). One study estimated that selecting the low-bVOC-emitting tree species over high-emitting species in a large-scale tree-planting initiative in Denver would be equivalent to avoiding emissions from nearly 500,000 cars from inner-city traffic (Curtis et al. 2014). ...
Better Forests, Better Cities evaluates how forests both inside and outside city boundaries benefit cities and their residents, and what actions cities can take to conserve, restore and sustainably manage those forests. This report is the first of its kind comprehensive resource on the connection between cities and forests, synthesizing hundreds of research papers and reports to show how all forest types can deliver a diverse suite of benefits to cities.
... For example, small-scale UGI such as street trees may provide allergies associated with grass pollen and damage to properties [77][78][79][80]. Some species release a significant amount of biogenic volatile organic compounds (VOCs), which, when combined with nitrogen oxides (NOx), can create particulate matter, secondary organic aerosol, and ozone, which exacerbate respiratory diseases such as asthma [81]. In addition, research shows that the risk of vegetables and soil contaminated by heavy metals and pollutants in community gardens and green roofs can be considered EDS [82]. ...
As cities are facing environmental and societal challenges, including climate change, rapid urbanization, and the COVID-19 pandemic, scholars and policymakers have recognized the potential of small-scale urban green infrastructures (UGI), such as rain gardens and street trees, to support important ecosystem services (ES) during periods of crisis and change. While there has been considerable research on the design, planning, engineering, and ecology of small-scale UGI, the governance modes of such spaces to support ES and manage ecosystem disservices (EDS) have received significantly less research attention. In this article, we provide a systematic review to evaluate how different modes of governance support different ES in small-scale green infrastructure. We evaluated governance in six types of small-scale green infrastructure: small parks, community gardens, vacant lands, rain gardens, green roofs, and street trees. Our review examines the different characteristics of four new governance approaches, including adaptive, network, mosaic, and transformative to understand their bottom-up nature and applicability in governing ES/disservices of small-scale UGI. Each governance mode can be effective for managing the ES of certain small-scale UGI, given their associations with principles such as resilience thinking, connectivity, and active citizenship. Our synthesis highlights knowledge gaps at the intersection between governance arrangements and ES in small-scale UGI. We conclude with a call for further research on the environmental and contextual factors that moderate the linkages between governance modes and ES/EDS in different types of UGI.
... In the developing countries, there are extensive areas where low-income residents live in congested neighbourhoods without much option of open or green spaces; so, provision of green walls and roofs can help in cooling the microclimate of the area. Curtis et al. (2014) flagged caution about the tree species emitting Biogenic Volatile Organic Compounds (BVOCs), but Singh et al. (1998) pointed out that in Indian cities, there are several such ornamental avenue trees which emit isoprene (a common VOC), and those need to be omitted from future plantation programmes. While shortlisting the suitable species, Air Pollution Tolerance Index (APTI) and Particulate Abatement Capacity (PAC) can be used as important indicators especially for roadside plantations to abate the air pollution preferring species like Ficus benghalensis, Mangifera indica and Carissa carandas (Kuddus et al. 2011). ...
Indisputably forest is one of the most significant natural resources and one-third of the land area of India is covered by forest which not only contributes extensively to the social and economic well-being of the rural people but also assures the sustainable growth of urban development through the preservation of the urban environment. However, in recent times, forests are being destroyed in the name of development, and the conversion of woodlands to others is an acute problem in India. At the same time, due to the lack of proper monitoring, these problems are increasing day by day. Statistical data on forest cover in India demonstrates the fact that - the destruction of forest cover largely depends on industrialization and urbanization. Asansol-Durgapur region of India is experiencing industrialization followed by urbanization in the last few decades. Though many studies have been conducted on the urban and industrial growth of the Asansol-Durgapur region, considering the importance of forest resources in the area. However, there is a substantial research gap in the study of the forest resource scenario of the study area. This study is an attempt to assess the forest resources management scenario of the Asansol-Durgapur (Industrial towns) region using geo-spatial technology. To conduct this study, satellite images of different periods for the study area have been acquired and analyzed. Different vegetation indices (e.g. Normalized Difference Vegetation Index, Soil Adjusted Vegetation Index), Land surface temperature (LST) have been derived to understand the nature and dimension of forest cover change in the study area. Supervised image classification of Landsat imageries from 1991 to 2021, measured the forest concentration in the study area, and correlated with the LST. The results show the reduction of sparse vegetation area (–34.201%), protected forest (−6.504%), and cultivated land (−26.142%), in the last 30 years. Similarly, maximum expansion is of opencast coal mining, industrial area, and, the built-up area also observed in the study area. The result also reveals that the loss of green area increases the surface temperature in Asansol and Durgapur industrial towns. Both the Asansol and Durgapur regions have recorded an increase of maximum and minimum land surface temperature from 31.64 °C to 39.64 °C and 18.83 °C to 24. °52 C respectively from 1991 to 2021. The overall study reveals that the forest cover of the study area declined due to, urbanization, and industrialization activities.KeywordsForest cover changeIndustrial townUrban green spaceLand Surface Temperature
... In the developing countries, there are extensive areas where low-income residents live in congested neighbourhoods without much option of open or green spaces; so, provision of green walls and roofs can help in cooling the microclimate of the area. Curtis et al. (2014) flagged caution about the tree species emitting Biogenic Volatile Organic Compounds (BVOCs), but Singh et al. (1998) pointed out that in Indian cities, there are several such ornamental avenue trees which emit isoprene (a common VOC), and those need to be omitted from future plantation programmes. While shortlisting the suitable species, Air Pollution Tolerance Index (APTI) and Particulate Abatement Capacity (PAC) can be used as important indicators especially for roadside plantations to abate the air pollution preferring species like Ficus benghalensis, Mangifera indica and Carissa carandas (Kuddus et al. 2011). ...
... In the developing countries, there are extensive areas where low-income residents live in congested neighbourhoods without much option of open or green spaces; so, provision of green walls and roofs can help in cooling the microclimate of the area. Curtis et al. (2014) flagged caution about the tree species emitting Biogenic Volatile Organic Compounds (BVOCs), but Singh et al. (1998) pointed out that in Indian cities, there are several such ornamental avenue trees which emit isoprene (a common VOC), and those need to be omitted from future plantation programmes. While shortlisting the suitable species, Air Pollution Tolerance Index (APTI) and Particulate Abatement Capacity (PAC) can be used as important indicators especially for roadside plantations to abate the air pollution preferring species like Ficus benghalensis, Mangifera indica and Carissa carandas (Kuddus et al. 2011). ...
Widespread urbanisation has depleted green cover increasing vulnerability to climate change, especially in the developing countries with India being no exception. While a handful of cities have been able to come up with integrated urban greenery provisions; the megalopolis of Kolkata having rich colonial legacy have failed to hold on to its green spaces due to rampant urbanisation waves. Urban greens
and urban forestry are probable ways to bridge the gap between city dwellers and their much-needed greenery, which has now been actively taken up by the governmental agencies. But urban greenery development relies largely on the attitude and involvement of urban residents. The apt species selection for plantation in the
heavily built-up milieu is lacking in the city. Kolkata is trying hard to have its desired share of man-made urban forest through the sprawling greens of over 7 acres, in New Town Rajarhat-east Kolkata, mirroring the centralised ‘Nagar Van’ scheme. This paper attempts to describe the global, national urban green scenario and specifically concentrates on Kolkata’s Urban Green Spaces (UGS) through preparation of tree-inventory, analytical study of spatio-temporal changing green cover with the help of land use and land cover (LULC), Normalized Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) analysis from LANDSAT imageries. The indices clearly show the declining trend of the green cover (1980–2020), and the regression analysis of NDVI and land surface temperature (LST) shows a strong
negative correlation. After investigating the loopholes in arboricultural practices, zones for peri-urban forest development have been chalked out. The perception studies of urban dwellers about the diverse role of urban forestry bring out that the residents are aware of the dire need to protect the green and have been taking part in developing the green spaces in the city.
... D'après les inventaires d'émission, les noisetiers sont enregistrés comme émettant seulement 0.1 µg gDW -1 h -1 de sesquiterpènes(Karl et al., 2009) mais n'émettent ni d'isoprène ni de monoterpènes. Cependant, Chapitre V : Présentation de la chambre VELVET et de ses premiers résultatsParra, Gassó and Baldasano, (2004) recensent des émissions de ces espèces mais toujours en très faible quantité (0.1 µg gDW -1 h -1 ).Une étude sur une espèce apparente, le noisetier de Byzance (Corylus corluna L.) montre des ratios d'émissions d'isoprène et de monoterpènes suivants : <0.1 µg g -1 h -1 et 1.30 µg g -1 h -1 pour l'isoprène et les monoterpènes respectivement(Curtis et al., 2014). A défaut de littérature sur l'espèce Corylus avellana, nous comparerons les ratios d'émission par COV avec l'espèce Corylus cornula L. composé majoritairement émis pour l'espèce cornula est l'ocimène avec un ratio d'émission de 0.572 µg g -1 h -1 . ...
Les composés organiques volatils (COVs) sont des composés clefs de l’atmosphère. Ils s’oxydent et forment de l’ozone troposphérique et des aérosols organiques secondaires (AOS) ayant un impact sanitaire et climatique important. Il est donc important de savoir quantifier leurs sources et leurs origines dans l’atmosphère. Plus particulièrement, les sources et origines de COVs biogéniques (COVB) sont souvent mal représentés et présentent de fortes disparités dans les milieux de mesure. Les COVs oxygénés (COVO) sont aussi des composés très réactifs dans l’atmosphère pour lesquels leur répartition est peu étudiée. L’analyse des déterminants de ces composés est nécessaire afin de comprendre les processus chimiques et dynamiques permettant leur modélisation. Un des déterminants est le transport de ces COVs au cours du temps. Il est crucial de coupler ces transports à la chimie atmosphérique pour prendre en compte tous les processus de transformation du COV. Dans ce contexte, le but de la thèse a été de concilier les considérations de chimie et de dynamique atmosphérique afin de mieux appréhender la problématique des COVs dans l’atmosphère et d’étudier les déterminants des COVs dans différents milieux naturels. Dans cette optique, les campagnes de mesures intensives OCTAVE, BIO-MAÏDO sur l’île de la Réunion et Sea2Cloud aux larges des côtes néo-zélandaises ont été effectuées. Les sources et origines en milieu tropical et océanique des COVs ont été étudiés. Dans un premier temps, à la Réunion, l’analyse factorielle (PMF) a montré que les sources de pollution de fond et anthropiques étaient les principaux contributeurs aux concentrations observées à l’observatoire du Maïdo (2200 m au-dessus du niveau de la mer). L’accent sur les origines du formaldéhyde par deux méthodes (Chemical kinetic based, CKB et PMF) a montré que celui-ci est majoritairement émis par des sources secondaires biogéniques. Dans un second temps, le couplage des mesures de concentrations en COVs et de la dynamique atmosphérique a été effectuée à l’aide du modèle Méso-CAT. En retraçant l’origine de la masse d’air, nous avons trouvé que celles-ci étaient principalement d’origine océanique et biogénique. Ensuite, les mesures en milieu océanique ont permis d’identifier et de quantifier de nouveaux composés à l’émission par les phytoplanctons : le benzène, toluène, éthylbenzène et xylènes (BTEX) ; composés habituellement mesurés en milieu anthropique. Enfin, le développement d’une chambre de mesure pour les émissions biogéniques a permis une première caractérisation des émissions par les feuilles des arbres au puy de Dôme.
... Environmental pVOC concentrations are, however, expected to be very low and therefore the particular GC-IMS applied for the AMMOD station is equipped with an in-line chip-based enrichment system, thus enabling quantification of pVOC down to the ppq concentration level (Vautz, Hariharan, & Weigend, 2018). Most publications on pVOC emissions are based on headspace analysis in a more or less static setup (Curtis et al., 2014). The set-up applied here has the advantage that measurements can be made quasi-continuously with consecutive sampling periods of 30 min, including automatic data evaluation. ...
Rapid changes of the biosphere observed in recent years are caused by both small and large scale drivers, like shifts in temperature, transformations in land-use, or changes in the energy budget of systems. While the latter processes are easily quantifiable, documentation of the loss of biodiversity and community structure is more difficult. Changes in organismal abundance and diversity are barely documented. Censuses of species are usually fragmentary and inferred by often spatially, temporally and ecologically unsatisfactory simple species lists for individual study sites. Thus, detrimental global processes and their drivers often remain unrevealed. A major impediment to monitoring species diversity is the lack of human taxonomic expertise that is implicitly required for large-scale and fine-grained assessments. Another is the large amount of personnel and associated costs needed to cover large scales, or the inaccessibility of remote but nonetheless affected areas.
To overcome these limitations we propose a network of Automated Multisensor stations for Monitoring of species Diversity (AMMODs) to pave the way for a new generation of biodiversity assessment centers. This network combines cutting-edge technologies with biodiversity informatics and expert systems that conserve expert knowledge. Each AMMOD station combines autonomous samplers for insects, pollen and spores, audio recorders for vocalizing animals, sensors for volatile organic compounds emitted by plants (pVOCs) and camera traps for mammals and small invertebrates. AMMODs are largely self-containing and have the ability to pre-process data (e.g. for noise filtering) prior to transmission to receiver stations for storage, integration and analyses. Installation on sites that are difficult to access require a sophisticated and challenging system design with optimum balance between power requirements, bandwidth for data transmission, required service, and operation under all environmental conditions for years. An important prerequisite for automated species identification are databases of DNA barcodes, animal sounds, for pVOCs, and images used as training data for automated species identification. AMMOD stations thus become a key component to advance the field of biodiversity monitoring for research and policy by delivering biodiversity data at an unprecedented spatial and temporal resolution.
... This study reveals the vital role of isoprene emissions from urban landscapes in modulating ozone formation. Previously, nine urban tree species in Denver has been examined to reveal that the selection of trees with low BVOC emission rates may be equivalent to the reduction in VOC emissions from a large number of cars (Curtis et al., 2014). Similarly, urban trees with low BVOC emission rates are likely to be essential in reducing the ozone forming potential (Calfapietra et al., 2013). ...
The impact of biogenic emissions on ozone and secondary organic aerosol (SOA) has been widely acknowledged; nevertheless, biogenic emissions emitted from urban landscapes have been largely ignored. We find that including urban isoprene in megacities like Beijing improves not only the modeled isoprene concentrations but also its diurnal cycle. Specifically, the mean bias of the simulated isoprene concentrations is reduced from 87% to 39% by adding urban isoprene emissions while keeping the diurnal cycle the same as that in non-urban or rural areas. Further adjusting the diurnal cycle of isoprene emissions to the urban profile steers the original early morning peak of the isoprene concentration to a double quasi-peak, i.e., bell shape, consistent with observations. The efficiency of ozone generation caused by isoprene emissions in urban Beijing is found to be twice as large as those in rural areas, indicative of vital roles of urban BVOC emissions in modulating the ozone formation. Our study also shows that in the future along with NOx emission reduction, isoprene emissions from urban landscapes will become more important for the formation of ozone in urban area, and their contributions may exceed that of isoprene caused by transport from rural areas. Finally, the impact of biogenic emissions on SOA is examined, revealing that biogenic induced SOA accounts for 16% of the total SOA in urban Beijing. The effect of isoprene on SOA (iSOA) is modulated through two pathways associated with the abundance of NOx emissions, and the effect can be amplified in future when NOx emissions are reduced. The findings of our study are not limited to Beijing but also apply to other megacities or densely populated regions, suggesting an urgent need to construct an accurate emission inventory for urban landscapes and evaluate their impact on ozone and SOA in air quality planning and management.
... All types of urban greenspace contribute to improving city air quality by filtering atmospheric particulates (Nowak et al., 2006) and this helps to reduce mortality. As Curtis, et al., (2014) found planting one million low-emitting tree species will prevent between 30,000 kilograms and 1.1 million kilograms in volatile organic compounds (VOC) emissions. Another study on the relationship between air pollution and premature deaths in Canada suggests that approximately 21,000 premature deaths are related to air pollution in Canada each year (Brauer et al., 2013). ...
Urban greenspaces have an immense contribution to the social, environmental, and economic spectrums of sustainable development. These three spectrums are also the foundation of Sustainable Development Goals (SDGs) 2030. Thus, this interdependence nature offers an opportunity to study the linkages between urban greenspaces and SDGs targets for acknowledging the importance of urban greenspaces for achieving SDGs 2030. To understand the linkages, the study follows a qualitative study approach. In the approach, a convenient systematic literature search technique has been employed to define urban greenspaces and identify empirical evidence on greenspaces’ contribution to different SDG targets. For ensuring the authenticity and validity of the findings, the study includes only peer-reviewed articles in the systematic technique. Results suggest an immediate association between urban greenspaces and SDG target 11.7, which emphasizes explicitly the provision (quality, quantity, and accessibility) of urban parks and playgrounds for the physical and mental wellbeing of urban citizens, typically the social spectrum of sustainable development. In addition to the apparent link, fourteen more underlying connections have been identified where urban greenspaces can contribute to fourteen different SDG targets. These underlying connections acknowledge the importance of urban greenspaces for achieving SDGs 2030.
... Related studies have addressed factors that influence residents' participation in TPIs (Locke et al., 2015;Hand et al., 2019), and how such participation influences urban tree canopy patterns (Locke and Morgan Grove, 2014). Others have assessed links between TPIs, canopy cover, income, race, and ethnicity (Watkins et al., 2017), as well as links to residential energy use (Nelson et al., 2012;Ko et al., 2015b;Erker and Townsend, 2019), carbon sequestration and hydrology (Pincetl et al., 2013), carbon life cycle (McPherson and Kendall, 2014), and emission of biogenic volatile organic compounds (Curtis et al., 2014). Of note, numerous studies have assessed the tree survival rates of TPIs and associated links to biophysical and sociopolitical factors (Oldfield et al., 2013;Koeser et al., 2014;Mincey and Vogt, 2014;Roman et al., 2014;Ko et al., 2015a;Roman et al., 2015;Vogt et al., 2015a,b;Widney et al., 2016;Blair et al., 2019;Breger et al., 2019). ...
Previous research has shown that trees and other roadside vegetation can mitigate adverse environmental conditions on urban street corridors, and, in turn, positively contribute to pedestrian perceptions of safety and walkability. In this study, pedestrian surveys (n = 181) were collected from three Massachusetts post-industrial cities to understand if street trees moderate pedestrian perceptions of safety. Three street tree conditions – sparse street tree abundance, mature street trees, and new street tree plantings – were compared as study settings. Several methods were used to correlate perceived safety with street trees and sociodemographic variables, including repeatedmeasures and between-group ANOVA, qualitative open-coding, exploratory factor analysis, and simple moderation analysis. This study did not find empirical evidence that street trees influence people's perceived safety, nor that street trees substantively contribute to feelings of safety while walking. These findings suggest that pedestrians do not have universal experiences of safety in walking environments, and different sociocultural backgrounds may contribute to diverging experiences of safety or fear when walking. Our research supports previous findings on the ways in which pedestrians value street trees; this can be extended to municipal or regional Complete Streets guidance and technical assistance programs.
... Related studies have addressed factors that influence residents' participation in TPIs (Locke et al., 2015;Hand et al., 2019), and how such participation influences urban tree canopy patterns (Locke and Morgan Grove, 2014). Others have assessed links between TPIs, canopy cover, income, race, and ethnicity (Watkins et al., 2017), as well as links to residential energy use (Nelson et al., 2012;Ko et al., 2015b;Erker and Townsend, 2019), carbon sequestration and hydrology (Pincetl et al., 2013), carbon life cycle (McPherson and Kendall, 2014), and emission of biogenic volatile organic compounds (Curtis et al., 2014). Of note, numerous studies have assessed the tree survival rates of TPIs and associated links to biophysical and sociopolitical factors (Oldfield et al., 2013;Koeser et al., 2014;Mincey and Vogt, 2014;Roman et al., 2014;Ko et al., 2015a;Roman et al., 2015;Vogt et al., 2015a,b;Widney et al., 2016;Blair et al., 2019;Breger et al., 2019). ...
Municipal leaders worldwide are showing substantial interest in urban greening. This encompasses incentives, policies, and programs to vegetate urban landscapes, and it often includes urban tree planting initiatives (TPIs). Over the past decade there has been a seven-fold increase in scholarly use of terms denoting TPIs, and roughly two-thirds of associated studies address TPIs in the United States (U.S.). This reflects a bloom of scholarly interest in TPIs. Yet, there has been limited research on contemporary TPIs as historically situated cultural phenomena, and there has to the best of our knowledge been no nationwide survey of TPIs across municipal scales. Addressing these gaps, this article presents findings from a survey of 41 TPIs in the United States. We report on typical traits of U.S. TPIs across six themes: background, dates and goals, public awareness, funding and governance, planting, and stewardship. Respondents identified over 115 traits that distinguish TPIs from typical urban tree planting activity, suggesting that TPIs are a discrete form of urban forestry. Over two-thirds of TPIs are funded separate from traditional urban forestry, and lack of institutionalization raises questions about long-term viability. TPIs mobilize political and financial resources for program launch, tree purchasing, and planting, but there may be a need for greater investment in stewardship activities and the social infrastructure that undergirds green infrastructure. Large shade trees for ecosystem services and native trees are the principal factors informing TPI species lists. Beautification and regulating ecosystem functions are, in turn, the principal potential benefits animating tree planting goals, yet few TPIs have conducted research to assess the fulfillment of associated outcomes. This study provides a foundation for future interdisciplinary scholarship on TPIs across the humanities, natural sciences , and social sciences.
... Related studies have addressed factors that influence residents' participation in TPIs (Locke et al., 2015;Hand et al., 2019), and how such participation influences urban tree canopy patterns (Locke and Morgan Grove, 2014). Others have assessed links between TPIs, canopy cover, income, race, and ethnicity (Watkins et al., 2017), as well as links to residential energy use (Nelson et al., 2012;Ko et al., 2015b;Erker and Townsend, 2019), carbon sequestration and hydrology (Pincetl et al., 2013), carbon life cycle (McPherson and Kendall, 2014), and emission of biogenic volatile organic compounds (Curtis et al., 2014). Of note, numerous studies have assessed the tree survival rates of TPIs and associated links to biophysical and sociopolitical factors (Oldfield et al., 2013;Koeser et al., 2014;Mincey and Vogt, 2014;Roman et al., 2014;Ko et al., 2015a;Roman et al., 2015;Vogt et al., 2015a,b;Widney et al., 2016;Blair et al., 2019;Breger et al., 2019). ...
Municipal leaders worldwide are showing substantial interest in urban greening. This encompasses incentives, policies, and programs to vegetate urban landscapes, and it often includes urban tree planting initiatives (TPIs). Over the past decade there has been a seven-fold increase in scholarly use of terms denoting TPIs, and roughly two-thirds of associated studies address TPIs in the United States (U.S.). This reflects a bloom of scholarly interest in TPIs. Yet, there has been limited research on contemporary TPIs as historically situated cultural phenomena, and there has to the best of our knowledge been no nationwide survey of TPIs across municipal scales. Addressing these gaps, this article presents findings from a survey of 41 TPIs in the United States. We report on typical traits of U.S. TPIs across six themes: background, dates and goals, public awareness, funding and governance, planting, and stewardship. Respondents identified over 115 traits that distinguish TPIs from typical urban tree planting activity, suggesting that TPIs are a discrete form of urban forestry. Over two-thirds of TPIs are funded separate from traditional urban forestry, and lack of institutionalization raises questions about long-term viability. TPIs mobilize political and financial resources for program launch, tree purchasing, and planting, but there may be a need for greater investment in stewardship activities and the social infrastructure that undergirds green infrastructure. Large shade trees for ecosystem services and native trees are the principal factors informing TPI species lists. Beautification and regulating ecosystem functions are, in turn, the principal potential benefits animating tree planting goals, yet few TPIs have conducted research to assess the fulfillment of associated outcomes. This study provides a foundation for future interdisciplinary scholarship on TPIs across the humanities, natural sciences , and social sciences.
... Related studies have addressed factors that influence residents' participation in TPIs (Locke et al., 2015;Hand et al., 2019), and how such participation influences urban tree canopy patterns (Locke and Morgan Grove, 2014). Others have assessed links between TPIs, canopy cover, income, race, and ethnicity (Watkins et al., 2017), as well as links to residential energy use (Nelson et al., 2012;Ko et al., 2015b;Erker and Townsend, 2019), carbon sequestration and hydrology (Pincetl et al., 2013), carbon life cycle (McPherson and Kendall, 2014), and emission of biogenic volatile organic compounds (Curtis et al., 2014). Of note, numerous studies have assessed the tree survival rates of TPIs and associated links to biophysical and sociopolitical factors (Oldfield et al., 2013;Koeser et al., 2014;Mincey and Vogt, 2014;Roman et al., 2014;Ko et al., 2015a;Roman et al., 2015;Vogt et al., 2015a,b;Widney et al., 2016;Blair et al., 2019;Breger et al., 2019). ...
Municipal leaders worldwide are showing substantial interest in urban greening. This encompasses incentives, policies, and programs to vegetate urban landscapes, and it often includes urban tree planting initiatives (TPIs). Over the past decade there has been a seven-fold increase in scholarly use of terms denoting TPIs, and roughly two-thirds of associated studies address TPIs in the United States (U.S.). This reflects a bloom of scholarly interest in TPIs. Yet, there has been limited research on contemporary TPIs as historically situated cultural phenomena, and there has to the best of our knowledge been no nationwide survey of TPIs across municipal scales. Addressing these gaps, this article presents findings from a survey of 41 TPIs in the United States. We report on typical traits of U.S. TPIs across six themes: background, dates and goals, public awareness, funding and governance, planting, and stewardship. Respondents identified over 115 traits that distinguish TPIs from typical urban tree planting activity, suggesting that TPIs are a discrete form of urban forestry. Over two-thirds of TPIs are funded separate from traditional urban forestry, and lack of institutionalization raises questions about long-term viability. TPIs mobilize political and financial resources for program launch, tree purchasing, and planting, but there may be a need for greater investment in stewardship activities and the social infrastructure that undergirds green infrastructure. Large shade trees for ecosystem services and native trees are the principal factors informing TPI species lists. Beautification and regulating ecosystem functions are, in turn, the principal benefits animating tree planting goals, yet few TPIs have conducted research to assess the fulfillment of associated outcomes. This study provides a foundation for future interdisciplinary scholarship on TPIs across the humanities, natural sciences, and social sciences.
... They also function as communication media within plant communities, between plants and between plants and insects (13). The London plane tree is one of the principal tree species responsible for emitting monoterpenes and sesquiterpenes (6,14), known to be implicated in the generation of atmospheric ozone (6,15). The Platanus pollen has been identified by the European Academy of Allergy and Clinical Immunology (EAACI) as an important allergen responsible for respiratory symptoms and was introduced as mandatory to investigate pollen allergen in all patients with suspicion of allergic rhinitis in Europe (16). ...
Respiratory allergies represent a major public health issue in the modern world. Pollens are among the most significant causes of seasonal allergic rhinitis, with pollens of wind-pollinated trees representing an important cause. Members of the Platanaceae family (Platanus acerifolia, Platanus orientalis) are well-recognized sources of allergenic pollens worldwide, due to their high capacity of sensitization and widespread usage as ornamental urban trees. Air pollution, characteristic to all important urban conglomerates in the world and provoked by diesel exhaust gases, industrial and domestic fumes, and biogenic volatile organic compounds represents another major public health issue. Plane trees, along with other species of trees, are one of the main sources of volatile compounds. Recent studies have demonstrated a strong correlation between air pollution and respiratory allergies, with airway chemical compounds intensifying the capacity of sensitization to allergenic pollens. This study presents an overview of the known negative elements on public health of the Platanus family.
... Some plant species may even act as the source of pollutants such as biogenic volatile organic carbon. Studies have shown that the selection of plant species for roadside plantation might have a substantial effect on volatile organic carbon emissions [17]. Therefore, plant species selection should be considered carefully while designing urban green belts and vegetation traffic barriers [18]. ...
Vegetation traffic barriers along roads can be an effective structure to improve roadside air quality and to reduce human exposure to traffic air pollutants. However, the selection of the plant species should be considered as an important design parameter for vegetation traffic barriers because different plant species demonstrate different levels of tolerance to air pollutants. This study compares the air pollution tolerance of different plant species found in the vegetation traffic barriers in the Kathmandu valley. Four biochemical parameters (relative water content, leaf extract pH, total chlorophyll and ascorbic acid) and the dust-capturing potential of plants were analyzed. Out of the nine selected species, Cinnamomum camphora showed the highest tolerance to air pollution based on the air pollution tolerance index. Similarly, Schefflera pueckleri, Psidium guajava and Ficus benjamina were found to be the sensitive species, while Ficus sp ., Nerium oleander , Thuja sp., Dypsis lutescens and Albizia julibrissin were found to have a moderate level of tolerance to air pollution. N. oleander had the highest dust-capturing potential. Considering both air pollution tolerance index and dust-capturing potential, C. camphora, N. oleander and A. julibrissin were found to be the most suitable species for the roadside plantation. The findings of this study might have important implications for plant species selection for vegetation traffic barriers.
... drought, heat and infestations). A recent study indicates that planting one million trees with low BVOC emissions compared, for example, to one million English oaks (trees considered high emitters) in Denver (USA), is comparable to preventing emissions from as many as 490,000 cars [57]. ...
The traditional emphasis of Public Health on the type and quality of housing today merges with other wider determinants of health such as: the neighbourhood, the community and the "place" where a home is located, but also the policies that make access to a healthy home within everyone's reach. At the neighbourhood scale, context-related aspects heavily influence the internal quality and real usability of the buildings themselves, with particular reference to factors such as the quality of the site, the relationship between the building and the context, the presence and quality of the greenery and open spaces surrounding the building, as well as all measures that make it possible to reduce the building's impact on the environment, to protect it against environmental pollution, and to manage the building in an integrated manner for maintenance purposes. Creating healthy living environments means referring to the different dimensions mentioned above, and this not only requires the attention of Public Health operators, but also implies an integration of vision and objectives among various professional skills and competences that puts health at the center of all policies. This proposal, which starts from the analysis of existing local hygiene regulations and scientific literature, aims to take stock of a number of areas considered fundamental for the assessment of building hygiene aspects, with particular reference to the eco-sustainability of buildings and adaptation to climate change. The aspects identified can be considered as a starting point for the preparation of integrated building and hygiene regulations based on documented effective practices for the protection of Public Health.
... However, the impact that Biogenic Volatile Organic Compounds (BVOCs) and allergens have on air quality is perhaps the most significant negative effect the London plane tree has on urban communities. In relation to BVOCs, the London plane tree is indicated as one of the main species of urban trees emitting monoterpenes and sesquiterpenes (Curtis et al., 2014), participating in the formation of atmospheric ozone (Xiaoshan et al., 2000). Regarding the emission of allergens, the involvement of Platanus pollen grains as a causative agent of respiratory symptoms is widely referenced (Varela et al., 1997;Valero et al., 1999;Alcázar et al., 2004;Iglesias et al., 2007;Nowak et al., 2012;Willis and Petrokofsky, 2017). ...
Platanus x hispanica (London plane) is a tree species widely used in urban areas due to the diversity of ecosystem services it provides. However, its functions also have some negative effects or associated disservices, such as the emission of Biogenic Volatile Organic Compounds (BVOCs) and allergens. This work aims to analyze the effect that urban environmental conditions and air pollutants have on pollen emissions of plane tree. The study has been carried out in Granada, in the southeast of the Iberian Peninsula, a city with a Mediterranean climate and one of the most polluted in Spain. Granada is also one of the Mediterranean cities in which the increase in the percentage of the population affected by allergy to Platanus pollen in recent decades has been most significant. The 1992–2019 Platanus pollen data series has been considered to establish the main aerobiological parameters, trends and correlations with meteorological variables and particulate and gaseous atmospheric pollutants, both before and during the flowering period. The average Seasonal Pollen Integral (SPIn) of about 2700 pollen grains has shown a significant increase throughout the series. This increase in allergen emissions could be related to the increase in crown volume associated with tree growth, but also to other environmental factors. Precipitation and minimum temperatures of the winter prior to flowering were the parameters that have shown the most influence with SPIn, while O3 and NOx are the pollutants that have the most effect on the peak value. Due to the good adaptation that London plane has to changing climatic conditions in urban environments, its hegemonic presence as an element of Urban Green infrastructure must be reviewed so that the net balance of ecosystem services is not diminished by the services.
... A color gradient indicates emission rates crossing the defined classes; gray indicates: "no data available." References: a (Aydin et al., 2014), b (Benjamin and Winer, 1998) * high ISO, c (EMEP/CORINAIR, 1999), d (Curtis et al., 2014), e (Geron et al., 1994), f , g (Hakola et al., 1998), h (Hakola et al., 2001), j (Hakola et al., 2006), k (Heinrich, 2007), l (Karl et al., 2009), m (König et al., 1995), n (Lamb et al., 1987), o (Meeningen et al., 2016) • low ISO, p (Owen et al., 1997), q (Paoletti et al., 2011), r (Préndez et al., 2013), s (Singh et al., 2007), t (Steinbrecher et al., 2009), u (Streiling andMatzarakis, 2003), v (Tarvainen et al., 2005), w (Tiwary et al., 2013), y (Veldt, 1989). influence i.a. ...
REVIEW Tropospheric ozone (O3) is one of the most prominent air pollution problems in Europe and other countries worldwide. Human health is affected by O3 via the respiratory as well the cardiovascular systems. Even though trees are present in relatively low numbers in urban areas, they can be a dominant factor in the regulation urban O3 concentrations. Trees affect the O3 concentration via emission of biogenic volatile organic compounds (BVOC), which can act as a precursor of O3, and by O3 deposition on leaves. The role of urban trees with regard to O3 will gain further importance as NOx concentrations continue declining and climate warming is progressing—rendering especially the urban ozone chemistry more sensitive to BVOC emissions. However, the role of urban vegetation on the local regulation of tropospheric O3 concentrations is complex and largely influenced by species-specific emission rates of BVOCs and O3 deposition rates, both highly modified by tree physiological status. In this review, we shed light on processes related to trees that affect tropospheric ozone concentrations in metropolitan areas from rural settings to urban centers, and discuss their importance under present and future conditions. After a brief overview on the mechanisms regulating O3 concentrations in urban settings, we focus on effects of tree identity and tree physiological status, as affected by multiple stressors, influencing both BVOC emission and O3 deposition rates. In addition, we highlight differences along the rural-urban gradient affecting tropospheric O3 concentrations and current knowledge gaps with the potential to improve future models on tropospheric O3 formation in metropolitan areas.
Accepted on 13 August 2019
Front. For. Glob. Change doi: 10.3389/ffgc.2019.00050
... Terpenes are a large and diverse family of naturally occurring organic compounds that are a major biosynthetic building block (de Meijere et al., 1998;Nicklaus et al., 2013). Vegetation including forests and agricultural crops (Curtis et al., 2014;Ormeño et al., 2010) emit substantial quantities of isoprene (a hemiterpene (C 5 H 8 )), monoterpenes (C 10 H 16 ) and sesquiterpenes (C 15 H 24 ) (Barkley et al., 2008;Jokinen et al., 2015;Smolander et al., 2014;Squire et al., 2014;Tao and Jain, 2005). ...
Monoterpenes play an important role in atmospheric chemistry due
to their large anthropogenic and biogenic emission sources and high chemical
reactivity. As a consequence, measurements are required to assess how changes
in emissions of monoterpenes impact air quality. Accurate and comparable
measurements of monoterpenes in indoor and outdoor environments require
gaseous primary reference materials (PRMs) that are traceable to the
international system of units (SI). PRMs of monoterpenes are challenging to
produce due to the high chemical reactivity and low vapour pressures of
monoterpenes and also their propensity to convert into other compounds,
including other terpenes. In this paper, the long-term stability of
gravimetrically prepared static monoterpene PRMs produced in differently
passivated cylinders, including sampling canisters, was assessed. We
demonstrate that static PRMs of multiple monoterpenes can be prepared and
used as a suitable long-term standard. For the first time the effect of
cylinder pressure and decanting from one cylinder to another on the chemical
composition and amount fraction of monoterpenes was also studied.
Gravimetrically prepared PRMs of limonene in high pressure cylinders were
compared to a novel portable dynamic reference gas generator based on
dilution of pure limonene vapour emitted from a permeation tube.
... For example, Llusia et al. (2010) studied 70 dominant vascular plants (half of the species are alien and the other half are native) at Oahu Island (the third largest of the Hawaiian island) in the USA. The emission of BVOCs from nine tree species were determined from Denver, CO, USA (Curtis et al. 2014). In Danum Valley Conservation Area (Borneo), Sardans et al. (2015) determined foliar terpene concentrations in 75 common woody plant species. ...
... For example, Llusia et al. (2010) studied 70 dominant vascular plants (half of the species are alien and the other half are native) at Oahu Island (the third largest of the Hawaiian island) in the USA. The emission of BVOCs from nine tree species were determined from Denver, CO, USA (Curtis et al. 2014). In Danum Valley Conservation Area (Borneo), Sardans et al. (2015) determined foliar terpene concentrations in 75 common woody plant species. ...
In this study, we examined 49 representative plant species of the Achanakmar-Amarkantak Biosphere Reserve (AABR) forest of Central India for emission of a number of biogenic volatile organic compounds (BVOCs). The BVOCs emissions from seven plant species are reported here for the first time. The emission rates of different plant species were ranged from negligible to 80.6 ± 0.82 (μgg⁻¹ h⁻¹). Forty-seven plant species were found to emit isoprene and monoterpenes (23 high emitters, 12 moderate emitters, and 12 low emitters). Dalbergia sissoo showed the maximum total average volatile organic compound (TAVOC) emission rates (80.6 μgg⁻¹ h⁻¹). The percentage composition of monoterpenes was also varied across different plant species. Alpha-pinene (α-pinene) was found as the most dominant monoterpene with about 41.40% of the total monoterpene emission. The highest emission range of α-pinene (7.8 μg g⁻¹ h⁻¹) was observed in Murraya koenigii. Carene was emitted only from two species (i.e., Mangifera indica and Terminalia tomentosa). When the emission rates of present study were compared to previous studies, there were considerable differences even for the same species. The study also reports the emission of BVOCs from Shorea robusta for the first time which is the most dominant plant species of the AABR (covering 60% of the total forest area).
... Such actions include concerted efforts to expand vegetated areas within the city [162], which have been shown to reduce air pollution and extreme temperatures in urban areas [163][164][165] and could also improve mental health outcomes [166,167]. Specifically, planting certain tree species can achieve substantial reductions in biogenic VOCs relative to known high-emitting species [168]. ...
Indian cities struggle with some of the highest ambient air pollution levels in the world. While national efforts are building momentum towards concerted action to reduce air pollution, individual cities are taking action on this challenge to protect communities from the many health problems caused by this harmful environmental exposure. In 2017, the city of Ahmedabad launched a regional air pollution monitoring and risk communication project, the Air Information and Response (AIR) Plan. The centerpiece of the plan is an air quality index developed by the Indian Institute of Tropical Meteorology’s System for Air Quality and Weather Forecasting and Research program that summarizes information from 10 new continuous air pollution monitoring stations in the region, each reporting data that can help people avoid harmful exposures and inform policy strategies to achieve cleaner air. This paper focuses on the motivation, development, and implementation of Ahmedabad’s AIR Plan. The project is discussed in terms of its collaborative roots, public health purpose in addressing the grave threat of air pollution (particularly to vulnerable groups), technical aspects in deploying air monitoring technology, and broader goals for the dissemination of an air quality index linked to specific health messages and suggested actions to reduce harmful exposures. The city of Ahmedabad is among the first cities in India where city leaders, state government, and civil society are proactively working together to address the country’s air pollution challenge with a focus on public health. The lessons learned from the development of the AIR Plan serve as a template for other cities aiming to address the heavy burden of air pollution on public health. Effective working relationships are vital since they form the foundation for long-term success and useful knowledge sharing beyond a single city.
... However, it is worth noting that emission parameters are uncertain. For example, monoterpene emission factors reported in the literature vary between 0.1 [66] and 43.5 [67] for Fagus, between 0 [68] and 9.6 [69] for Fraxinus, and between 0 [70] and 1.2 [71] for Tilia. For subtropical street trees, Dunn-Johnston et al. (2016) [72] showed that a considerable difference exists between species-derived isoprene emission rates and those assumed (genus-specific emission rates) in i-Tree Eco. ...
Ecosystem modeling can help decision making regarding planting of urban trees for climate change mitigation and air pollution reduction. Algorithms and models that link the properties of plant functional types, species groups, or single species to their impact on specific ecosystem services have been developed. However, these models require a considerable effort for initialization that is inherently related to uncertainties originating from the high diversity of plant species in urban areas. We therefore suggest a new automated method to be used with the i-Tree Eco model to derive light competition for individual trees and investigate the importance of this property. Since competition depends also on the species, which is difficult to determine from increasingly used remote sensing methodologies, we also investigate the impact of uncertain tree species classification on the ecosystem services by comparing a species-specific inventory determined by field observation with a genus-specific categorization and a model initialization for the dominant deciduous and evergreen species only. Our results show how the simulation of competition affects the determination of carbon sequestration, leaf area, and related ecosystem services and that the proposed method provides a tool for improving estimations. Misclassifications of tree species can lead to large deviations in estimates of ecosystem impacts, particularly concerning biogenic volatile compound emissions. In our test case, monoterpene emissions almost doubled and isoprene emissions decreased to less than 10% when species were estimated to belong only to either two groups instead of being determined by species or genus. It is discussed that this uncertainty of emission estimates propagates further uncertainty in the estimation of potential ozone formation. Overall, we show the importance of using an individual light competition approach and explicitly parameterizing all ecosystem functions at the species-specific level.
... Therefore, the BVOC emission into the urban atmosphere should be investigated for its effect on air quality. Curtis et al. (2014) reported the BVOC emission from trees in urban area. Because emission of the BVOC highly depends on the species of tree, it is necessary to investigate the BVOC emission of each species. ...
Ozone concentration in Tokyo Metropolitan area is one of the most serious issues of the local air quality. Tropospheric ozone is formed by radical reaction including volatile organic compound (VOC) and nitrogen oxides (NOx). Reduction of the emission of reactive VOC is a key to reducing ozone concentrations. VOC is emitted from anthropogenic sources and also from vegetation (biogenic VOC or BVOC). BVOC also forms ozone through NOx and radical reactions. Especially, in urban area, the BVOC is emitted into the atmosphere with high NOx concentration. Therefore, trees bordering streets and green spaces in urban area may contribute to tropospheric ozone. On the other hand, not all trees emit BVOC which will produce ozone locally. In this study, BVOC emissions have been investigated (terpenoids: isoprene, monoterpenes, sesquiterpenes) for 29 tree species. Eleven in the 29 species were tree species that did not emit BVOCs. Three in 12 cultivars for future planting (25 %) were found to emit no terpenoid BVOCs. Eight in 17 commonly planted trees (47%) were found to emit no terpenoid BVOC. Lower-emitting species have many advantages for urban planting. Therefore, further investigation is required to find the species which do not emit terpenoid BVOC. Emission of reactive BVOC should be added into guideline for the urban planting to prevent the creation of sources of ozone. It is desirable that species with no reactive BVOC emission are planted along urban streets and green areas in urban areas, such as Tokyo.
... Although the β-caryophyllene emission rate is driven by temperature and light [Hansen and Seufert, 2003], β-caryophyllene emissions from plants have large species-to-species differences. As reported by Curtis et al. [2014], β-caryophyllene was only detected in one of nine urban tree species. Large tree-to-tree variations in sesquiterpene emissions were observed, even from the same species [Haapanala et al., 2009;Hakola et al., 2001]. ...
A majority of global secondary organic aerosol (SOA) comes from terpenoids. In this study, we carried out a one-year nationwide observation of pinenes (α- and β-pinene) and SOA tracers from monoterpenes (SOAM) and β-caryophyllene (SOAC) over China for the first time. SOAM and SOAC tracers ranged from 9.80 to 49.0 ng m-3 and 1.72 to 7.72 ng m-3, respectively, with high levels in southern China. Pinenes ranged from 34 to 102 pptv, with α-pinene dominant over β-pinene. SOAM tracers were correlated between paired sites, suggesting a regional impact of SOAM, while pinenes were uncorrelated between sites due to their rapid oxidation. High levels of SOAM tracers were observed in spring and summer. However, at the Hailun site in Northeast China, SOAM tracers increased during winter. The positive correlation between SOAM tracers and the biomass burning (BB) tracer levoglucosan during winter at Hailun indicated that the unexpected increase of SOAM was associated with BB. The SOAC tracer, β-caryophyllenic acid, increased during winter and was positively correlated with levoglucosan, suggesting substantial contributions from BB to SOAC production in wintertime. Together with SOA tracers from isoprene, these tracers were applied to estimate biogenic secondary organic carbon (BSOC) from isoprene, monoterpenes and β-caryophyllene. The annual average BSOC was 0.91 ± 0.41 μgC m-3,with the majority from monoterpenes and the highest level in Southwest China. BSOC was elevated from April to September and was lowest in January and February. BSOC composition dramatically changed from a monoterpene majority in fall-spring to an isoprene majority in summer.
The reactions of limonene with various free radicals (•OCH3, •OBr, •SH, •OOH, and •OOCH3) were investigated along the 273.15–312.15 K temperature range. To that purpose the density functional theory was used, at the M06‐2X/6–311+g(d,p) level. Two reaction mechanisms, hydrogen atom transfer (HAT) and radical adduct formation (RAF) were considered. It was found that the relative reactivity of the studied radicals toward limonene is: •SH > •OBr > •OCH3 > •OOH > •OOCH3. HAT was identified as the dominant mechanism for •OOH and •OOCH3, while RAF contributes the most to the reactions involving •OCH3, •OBr, and •SH. The obtained Arrhenius expressions are: k(•OCH3) = 1.58 × 10−13 e−1.59/RT, k(•OBr) = 3.55 × 10−12 e+1.82/RT, k(•SH) = 3.30 × 10−11 e+0.79/RT, k(•OOH) = 1.33 × 10−15 e−5.99/RT, and k(•OOCH3) = 5.88 × 10−17 e−6.26/RT. According to them, the reactions of •OBr and •SH become slower as temperature rises from 273.15 to 312.15 K, while for the other radicals the reactions rate increases with temperature. The subsequent tropospheric fate of the most abundant •OBr adduct was also investigated in the same temperature range, considering O2 addition to this radical (step 2) and the reaction of the peroxyl radical yielded in this step 2 with NO. The latter is predicted to take place in two steps: the NO addition (3a) and the NO2 elimination (3b). The corresponding Arrhenius expression are k2 = 3.56 × 10−15 e+1.43/RT and k3b = 1.35 × 1014 e−31.65/RT. Step 3a was found to be barrierless. To our best knowledge, all the data provided here is reported for the first time. Thus, it would hopefully contribute to enhance the knowledge necessary for the full understanding (and accurate modeling) of the troposphere. In addition to the previously reported capability of limonene to act as •OH, •NO3, and O3 scavenger, it also reacts with •OCH3, •OBr, •SH, •OOH, and •OOCH3 radicals. Thus, it can be considered as a versatile tropospheric free radical deactivator.
Urban living is becoming increasingly predominant, with 55% of the world’s population currently living in cities and 68% projected to do so by 2050 (1). While megacities with more than 10 million inhabitants command much attention, they account for less than 10% of the world’s urban population. In contrast, nearly half of all urban residents – over 2 billion people – live in cities with populations under 500,000 (Table 9.1). It is in these smaller cities where population growth rates tend to be highest. The USA, Latin America, and Japan are very highly urbanized but both Africa as a whole and India remain well below 50% urbanized (Figure 9.1). Many low- and lower-middle-income countries in particular are projected to urbanize rapidly in coming decades, with a projected increase of 2.5 billion people in urban areas by 2050 – accounting for essentially all projected human population growth through mid-century.
The interactions of two molecules of water with the terpene limonene are characterised by chirped-pulse Fourier transform microwave spectroscopy. Seven isomers of limonene-(H2O)2 have been observed, and identified from the comparison of their experimental spectroscopic parameters with those predicted by computational methods. In all isomers a distorted water dimer binds to limonene through O-H⋯π and C-H⋯O interactions, and shows a strong preference for interacting with equatorial conformations of limonene. O-H⋯π hydrogen bonds to both endocyclic and exocyclic double bonds of limonene are established. In one of the isomers the water dimer forms a bridge between the endocyclic and exocyclic double bonds of limonene. Our results help advance our understanding of the interactions of water with atmospheric compounds.
Traffic emission has been identified as one of the dominant sources of fine particulate matter (PM2.5) in Thailand, and urban green spaces have the capacity to mitigate air pollution. Taking Bangkok as the study area, one of the most polluted cities in Thailand, this study investigated the effect of vegetation on PM2.5 concentration at three different sites with different vegetation characteristics in Chatuchak Park, an urban park located in Bangkok. Sensors were installed at the park to measure PM2.5 and metrological parameters at the roadside and different distances inside the park away from the road, and the ENVI-met model was run to simulate PM2.5 concentration in the three study sites. The result shows that PM2.5 concentration behind the vegetation barrier was reduced 34% on average compared to the concentration next to the road at the three sites. The effect of vegetation on meteorological factors was clearly seen near the park border with a hedgerow grown along the border. The order of influence of meteorological factors on PM2.5 concentration was relative humidity > potential temperature > wind speed > wind direction. Two scenarios including changes in weather patterns and types of vegetation that affect PM2.5 concentration were studied. Changing in the wind direction from oblique to perpendicular to the park had no significant effect on PM2.5 concentration as long as there is a dense hedgerow along the park border. Comparing to the current vegetation, sparse vegetation with less leaf area density and higher crown base heights had lower impact to mitigate PM2.5 concentration in the park. Our study provides information on vegetation and landscape strategies which can provide good air quality in the urban parks for better park design in the future.
Natural emissions play a key role in modulating the formation of ground-level ozone (O3), especially emissions of biogenic volatile organic compounds (BVOCs) and soil nitric oxide (SNO), and their individual effects on O3 formation have been previously quantified and evaluated. However, their synergistic effects remain unclear and have not yet been well assessed. By applying the Weather Research and Forecasting (WRF) model coupled with the Chemistry-Model of Emissions of Gases and Aerosols from Nature (WRF/Chem-MEGAN) model, this study reveals that in the presence of sufficient BVOC emissions, which act as a fuel, SNO emissions act as a fuel additive and promote the chemical reactions of BVOCs and the subsequent production of O3. Consequently, the synergistic effects of BVOC and SNO emissions on summertime O3 production surpassed the sum of their individual effects by as much as 10–20 μg m⁻³ in eastern China in 2014. In order to reduce O3 concentration to a level corresponding to no natural emissions of BVOC or SNO (i.e., the BASE scenario), the anthropogenic volatile organic compound (AVOC) emissions in the scenario considers BVOC and SNO emissions must be reduced by 1.76 times that of the BASE scenario. This study demonstrates that the synergistic effects of BVOC and SNO emissions can impede ground-level O3 regulation and can subsequently impose stricter requirements on anthropogenic precursor emission control in China. The results of this study can also inform efforts in other regions that are still combating ground-level O3 pollution.
The species of the genus Platanus L. are widely used in urban green infrastructure in Bulgaria and abroad, but are proven to be a serious source of allergen pollen emissions. The number of people, affected by pollinosis, is increasing every year and this affects the world economy and health of the population in a high level. The pollen of the plane tree is light, very small and spreads anemophilically. This is one of the genera that produce the largest amount of pollen per inflorescence. This makes Platanus a tree of a high allergy potential that has the tendence to get higher in time, because of its increasing use in urban green spaces. The aim of this study is to collect data for allergy potential of the three species of plane tree in some of the European countries, where the allergy is a significant problem, and to compare the sensitization of patients to its pollen in Bulgaria.
Limonene with endo- and exo-double bonds is a significant monoterpene in the atmosphere and has high reactivity towards O3. We investigated the atmospheric oxidation mechanism of limonene ozonolysis using a high level quantum chemistry calculation coupled with RRKM-ME kinetic simulation. The additions of O3 can take place at both the endo- and exo-double bonds with a branching ratio of 0.87 : 0.13, forming four major highly energized CIs* (named Syn-2a*, Syn-2b*, Anti-2b* and Anti-2c*) with the relative higher fractions of 0.21 : 0.35 : 0.27 : 0.11. A yield of 4% for Limona-ketone was obtained as well. For the unimolecular isomerization pathways of limonene + O3 → POZs → CIs* → SOZ, VHP, or dioxirane, five, one, or none of the internal rotations are treated as hindered internal rotors for CIs*. We obtained percentages of 0.59 : 0.18 : 0.14 in total for separate isomerization routes in the formation of VHPs, dioxirane and SOZs from CIs* using the fourth-order Runge-Kutta method. Additionally, a yield of ∼5% was acquired for stabilized CIs compiling the fractions of different addition routes. About ∼10% of stabilized Anti-2b would isomerize to VHP and 90% would isomerize to SOZs. Isomerization to VHPs dominates the fate of stabilized Syn-2a, Syn-2b and Anti-2c. The overall yield of OH radicals was 0.61. Our study suggested a yield of 0.17 for stabilized SOZs and 0.18 for dioxirane, although both their fates are ambiguous.
Cambridge Core - Ecology and Conservation - Trees and Global Warming - by William J. Manning
Sound management of soil nutrients is critical for optimizing crop vegetative and reproductive development and realizing high yields in irrigated cropping systems. This paper discusses the work done in Africa and presents lessons from other parts of the world for improved nutrient management under irrigation. Considering the rising temperatures and erratic rainfall as a consequence of climatic change and depleted soil nutrients as a result of continuous cropping, this review offers remedial options for managing soil fertility while optimizing water use and crop yields. The paper intends to inform agricultural policy makers and help farmers and organizations in Africa to manage soil nutrient and water resources efficiently and achieve high yields. Importantly, this discussion should stimulate further research in nutrient and water management under varying ecological scenarios of southern Africa to provide a cogent basis for climate change adaptation interventions.
Worldwide more and more people live and work in cities, where urban nature
and their ecosystem services
are the basis for economic development and social wellbeing. Therefore, how to ensure that cities in the present and future can provide a whole range of ecosystem services to meet urban dwellers’ needs become a front and center issue in urban resilience and sustainability on the global agenda. This article presents a literature review that explores our understanding about various natural elements in cities (including urban green and blue spaces) and their diverse ecosystem services and some disservices
. While the importance of urban nature and urban ecosystem
services
has been increasingly recognized, the integration of ecological, social and economic understanding of urban ecosystem services into relevant policy making processes is still at an embryonic stage. Some pertinent challenges are highlighted for the theorization and governance
of urban ecosystem services.
Urban greenery generates many tangible and intangible benefits and contributes to improving environmental quality, quality of life and sustainable urban development. Research on various aspects of urban vegetation such as carbon sequestration, removing air pollutants, reducing noise, providing recreational amenity benefits is in infancy stage in India. This paper reviews few significant studies in different spheres of urban greenery from Indian cities. Some issues related to development and research in this direction and future management strategies to be adopted have been discussed.
The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1) is a modeling framework for estimating fluxes of 147 biogenic compounds between terrestrial ecosystems and the atmosphere using simple mechanistic algorithms to account for the major known processes controlling biogenic emissions. It is available as an offline code and has also been coupled into land surface models and atmospheric chemistry models. MEGAN2.1 is an update from the previous versions including MEGAN2.0 for isoprene emissions and MEGAN2.04, which estimates emissions of 138 compounds. Isoprene comprises about half of the estimated total global biogenic volatile organic compound (BVOC) emission of 1 Pg (1000 Tg or 10<sup>15</sup> g). Another 10 compounds including methanol, ethanol, acetaldehyde, acetone, α-pinene, β-pinene, t −β-ocimene, limonene, ethene, and propene together contribute another 30% of the estimated emission. An additional 20 compounds (mostly terpenoids) are associated with another 17% of the total emission with the remaining 3% distributed among 125 compounds. Emissions of 41 monoterpenes and 32 sesquiterpenes together comprise about 15% and 3%, respectively, of the total global BVOC emission. Tropical trees cover about 18% of the global land surface and are estimated to be responsible for 60% of terpenoid emissions and 48% of other VOC emissions. Other trees cover about the same area but are estimated to contribute only about 10% of total emissions. The magnitude of the emissions estimated with MEGAN2.1 are within the range of estimates reported using other approaches and much of the differences between reported values can be attributed to landcover and meteorological driving variables. The offline version of MEGAN2.1 source code and driving variables is available from http://acd.ucar.edu/~guenther/MEGAN/MEGAN.htm and the version integrated into the Community Land Model version 4 (CLM4) can be downloaded from http://www.cesm.ucar.edu/ .
Emissions of biogenic volatile organic compounds (BVOC) from urban trees during and after blooming were measured during spring and early summer 2009 in Boulder, Colorado. Air samples were collected onto solid adsorbent cartridges from branch enclosures on the tree species crabapple, horse chestnut, honey locust, and hawthorn. These species constitute ~65 % of the insect-pollinated fraction of the flowering tree canopy (excluding catkin-producing trees) from the street area managed by the City of Boulder. Samples were analyzed for C<sub>10</sub>–C<sub>15</sub> BVOC by thermal desorption and gas chromatography coupled to a flame ionization detector and a mass spectrometer (GC/FID/MS). Identified emissions and emission rates from these four tree species during the flowering phase were found to vary over a wide range. Monoterpene emissions were identified for honey locust, horse chestnut and hawthorn. Sesquiterpene emissions were observed in horse chestnut and hawthorn samples. Crabapple flowers were found to emit significant amounts of benzyl alcohol and benzaldehyde. Floral BVOC emissions increased with temperature, generally exhibiting exponential temperature dependence. Changes in BVOC speciation during and after the flowering period were observed for every tree studied. Emission rates were significantly higher during the blooming compared to the vegetative state for crabapple and honey locust. Total normalized (30 °C) monoterpene emissions from honey locust were higher during flowering (5.26 μg Cg<sup>−1</sup> h<sup>−1</sup>) than after flowering (1.23 μg Cg<sup>−1</sup> h<sup>−1</sup>). The total normalized BVOC emission rate from crabapple (93 μg Cg<sup>−1</sup> h<sup>−1</sup>) during the flowering period is of the same order as isoprene emissions from oak trees, which are among the highest BVOC emissions observed from plants to date. These findings illustrate that during the relatively brief springtime flowering period, floral emissions constitute by far the most significant contribution to the BVOC flux from these tree species, some of which are leafless at this time. Experimental results were integrated into the MEGAN biogenic emission model and simulations were performed to estimate the contribution of floral BVOC emissions to the total urban BVOC flux during the spring flowering period. The floral BVOC emitted during this three-month simulation are equivalent to 11 % of the cumulative monoterpene flux for the Boulder urban area.
A biogenic emissions scheme has been incorporated in the global dynamic vegetation model ORCHIDEE ( Organizing Carbon and Hydrology in Dynamic EcosystEms) in order to calculate global biogenic emissions of isoprene, monoterpenes, methanol, acetone, acetaldehyde, formaldehyde and formic and acetic acids. Important parameters such as the leaf area index are fully determined by the global vegetation model and the influences of light extinction ( for isoprene emissions) and leaf age ( for isoprene and methanol emissions) are also taken into account. We study the interannual variability of biogenic emissions using the satellite-based climate forcing ISLSCP-II as well as relevant CO2 atmospheric levels, for the 1983 - 1995 period. Mean global emissions of 460 TgC/yr for isoprene, 117 TgC/yr for monoterpenes, 106 TgC/yr for methanol and 42 TgC/yr for acetone are predicted. The mean global emission of all biogenic compounds is 752 +/- 16 TgC/yr with extremes ranging from 717 TgC/yr in 1986 to 778 TgC/yr in 1995, that is a 8.5% increase between both. This variability differs significantly from one region to another and among the regions studied, biogenic emissions anomalies were the most variable in Europe and the least variable in Indonesia ( isoprene and monoterpenes) and North America ( methanol). Two scenarios of land use changes are considered using the 1983 climate and atmospheric CO2 conditions, to study the sensitivity of biogenic emissions to vegetation alteration, namely tropical deforestation and European afforestation. Global biogenic emissions are highly affected by tropical deforestation, with a 29% decrease in isoprene emission and a 22% increase in methanol emission. Global emissions are not significantly affected by European afforestation, but on a European scale, total biogenic VOCs emissions increase by 54%.
The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1) is a modeling framework for estimating fluxes of biogenic compounds between terrestrial ecosystems and the atmosphere using simple mechanistic algorithms to account for the major known processes controlling biogenic emissions. It is available as an offline code and has also been coupled into land surface and atmospheric chemistry models. MEGAN2.1 is an update from the previous versions including MEGAN2.0, which was described for isoprene emissions by Guenther et al. (2006) and MEGAN2.02, which was described for monoterpene and sesquiterpene emissions by Sakulyanontvittaya et al. (2008). Isoprene comprises about half of the total global biogenic volatile organic compound (BVOC) emission of 1 Pg (1000 Tg or 1015 g) estimated using MEGAN2.1. Methanol, ethanol, acetaldehyde, acetone, α-pinene, β-pinene, t-β-ocimene, limonene, ethene, and propene together contribute another 30% of the MEGAN2.1 estimated emission. An additional 20 compounds (mostly terpenoids) are associated with the MEGAN2.1 estimates of another 17% of the total emission with the remaining 3% distributed among >100 compounds. Emissions of 41 monoterpenes and 32 sesquiterpenes together comprise about 15% and 3%, respectively, of the estimated total global BVOC emission. Tropical trees cover about 18% of the global land surface and are estimated to be responsible for ~80% of terpenoid emissions and ~50% of other VOC emissions. Other trees cover about the same area but are estimated to contribute only about 10% of total emissions. The magnitude of the emissions estimated with MEGAN2.1 are within the range of estimates reported using other approaches and much of the differences between reported values can be attributed to land cover and meteorological driving variables. The offline version of MEGAN2.1 source code and driving variables is available from
Increases in atmospheric volatile organic compounds (VOC), especially in
relation to biogenic VOC (BVOC), and haze days that affect the built-up
areas are believed to be closely correlated. The present study aims to
provide a spatially and temporally resolved BVOC inventory of a
subtropical urban-rural complex, the Greater Hangzhou Area (GHA) in
China. Urban green space was subdivided into block green space and
linear green space; rural areas were classified into four primary forest
types. A field survey was conducted to assess the vegetation composition
(species, size) and foliar mass of each tree species. BVOC emission
potentials were obtained from measurement and literature. Results showed
(1) the emission intensity (annual BVOC emissions per land area) in the
entire GHA is
3.37 × 106 g C km-2 yr-1,
and rural forest (excluding bamboo forest) exhibits lower average
emission intensity
(2.74 × 106 g C km-2 yr-1)
than that of urban green space
(3.13 × 106 g C km-2 yr-1);
(2) Within the built-up area, the block green space has higher emission
intensity
(3.93 × 106 g C km-2 yr-1)
than the linear green space
(2.63 × 106 g C km-2 yr-1);
(3) in Hangzhou city, BVOC emissions of native and exotic trees
exhibited no differences; and (4) in rural areas, bamboo forests and
coniferous forests were the major contributors of BVOC emissions,
whereas the original vegetation type of this region, evergreen
broad-leaved forest, possessed lower BVOC emissions. The results suggest
that total BVOC emission can be controlled to low levels by planting
low-emitting species in built-up areas while restoring original
broad-leaved forest vegetation in rural areas.
Light and temperature are known to be the most important environmental factors controlling biogenic volatile organic compound (BVOC) emissions from plants, but little is known about their interdependencies especially for BVOCs other than isoprene. We studied light responses at different temperatures and temperature responses at different light levels of foliar BVOC emissions, photosynthesis and chlorophyll fluorescence on Quercus coccifera, an evergreen oak widespread in Mediterranean shrublands. More than 50 BVOCs were detected in the emissions from Q. coccifera leaves most of them being isoprenoids plus a few green leaf volatiles (GLVs). Under standard conditions non-oxygenated monoterpenes (MT-hc) accounted for about 90 % of the total BVOC release (mean ± SD: 738 ± 378 ng m-2 projected leaf area s-1 or 13.1 ± 6.9 mug g-1 leaf dry weight h-1) and oxygenated monoterpenes (MT-ox) and sesquiterpenes (SQTs) accounted for the rest in about equal proportions. Except GLVs, emissions of all BVOCs responded positively to light and temperature. The light responses of MT and SQT emissions resembled that of CO2-assimilation and were little influenced by the assay temperature: at high assay temperature, MT-hc emissions saturated at lower light levels than at standard assay temperature and tended even to decrease in the highest light range. The emission responses to temperature showed mostly Arrhenius-type response curves, whose shapes in the high temperature range were clearly affected by the assay light level and were markedly different between isoprenoid classes: at non-saturating light, all isoprenoids showed a similar temperature optimum (~43 °C), but, at higher temperatures, MT-hc emissions decreased faster than MT-ox and SQT emissions. At saturating light, MT-hc emissions peaked already around 37 °C and rapidly dropped at higher temperatures, whereas MT-ox and SQT emissions strongly increased between 40 and 50 °C accompanied by a burst of GLVs. In all experiments, decreases of MT-hc emissions under high temperatures were correlated with decreases in CO2-assimilation and/or photosynthetic electron transport. We conclude that light and temperature can have interactive short-term effects on the quantity and quality of BVOC emissions from Q. coccifera through substrate limitations of MT biosynthesis occurring at temperatures supraoptimal for photosynthetic processes that are exacerbated by oxidative stress and membrane damages. Such interactive effects are likely to occur frequently during hot and dry summers and simulations made in this work showed that they may have important consequences for emission predictions.
Urban trees can potentially mitigate environmental degradation accompanying rapid urbanisation via a range of tree benefits and services. But uncertainty exists about the extent of tree benefits and services because urban trees also impose costs (e.g. asthma) and may create hazards (e.g. windthrow). Few researchers have systematically assessed how urban tree benefits and costs vary across different cities, geographic scales and climates. This paper provides a quantitative review of 115 original urban tree studies, examining: (i) research locations, (ii) research methods, and (iii) assessment techniques for tree services and disservices. Researchers published findings in 33 journals from diverse disciplines including: forestry, land use planning, ecology, and economics. Research has been geographically concentrated (64% of studies were conducted in North America). Nearly all studies (91.3%) used quantitative research, and most studies (60%) employed natural science methods. Demonstrated tree benefits include: economic, social, health, visual and aesthetic benefits; identified ecosystem services include: carbon sequestration, air quality improvement, storm water attenuation, and energy conservation. Disservices include: maintenance costs, light attenuation, infrastructure damage and health problems, among others. Additional research is required to better inform public policy, including comparative assessment of tree services and disservices, and assessment of urban residents and land managers’ understanding of tree benefits and costs.
Vehicle emissions of volatile organic compounds
(VOCs) were determined at the Shing Mun Tunnel, Hong
Kong in summer and winter of 2003. One hundred and ten
VOCs were quantified in this study. The average concentration
of the total measured VOCs at the inlet and outlet of
the tunnel were 81 250 pptv and 117 850 pptv, respectively.
Among the 110 compounds, ethene, ethyne and toluene were
the most abundant species in the tunnel. The total measured
VOC emission factors ranged from 67 mg veh−1 km−1 to
148 mg veh−1 km−1, with an average of 115 mg veh−1 km−1.
The five most abundant VOCs observed in the tunnel were,
in decreasing order, ethene, toluene, n-butane, propane and
i-pentane. These five most abundant species contributed over
38% of the total measured VOCs emitted. The high propane
and n-butane emissions were found to be associated with liquefied
petroleum gas (LPG)-fueled taxis. Fair correlations
were observed between marker species (ethene, i-pentane,
n-nonane, and benzene, toluene, ethylbenzene and xylenes –
BTEX) with fractions of gasoline-fueled or diesel-fueled vehicles.
Moreover, ethene, ethyne, and propene are the key
species that were abundant in the tunnel but not in gasoline
vapors or LPG. The ozone formation potential from the
VOCs in Hong Kong was evaluated by the maximum increment
reactivity (MIR). It was found to be 568 mg of ozone per vehicle per kilometer traveled. Among them, ethene,
propene and toluene contribute most to the ozone-formation
reactivity.
Emissions of biogenic volatile organic compounds (BVOC) from urban trees during and after blooming were measured during spring and early summer 2009 in Boulder, Colorado. Air samples were collected onto solid adsorbent cartridges from branch enclosures on the tree species crabap-ple (Malus sp.), horse chestnut (Aesculus carnea, "Ft. Mc-Nair"), honey locust (Gleditsia triacanthos, "Sunburst"), and hawthorn (Crataegus laevigata, "Pauls Scarlet"). These species constitute ∼ 65 % of the insect-pollinated fraction of the flowering tree canopy (excluding catkin-producing trees) from the street area managed by the City of Boulder. Samples were analyzed for C 10 –C 15 BVOC by thermal desorption and gas chromatography coupled to a flame ionization detec-tor and a mass spectrometer (GC/FID/MS). Identified emis-sions and emission rates from these four tree species during the flowering phase were found to vary over a wide range. Monoterpene emissions were identified for honey locust, horse chestnut and hawthorn. Sesquiterpene emissions were observed in horse chestnut and hawthorn samples. Crabap-ple flowers were found to emit significant amounts of ben-zyl alcohol and benzaldehyde. Floral BVOC emissions in-creased with temperature, generally exhibiting exponential temperature dependence. Changes in BVOC speciation dur-ing and after the flowering period were observed for every tree studied. Emission rates were significantly higher dur-ing the blooming compared to the post-blooming state for crabapple and honey locust. The results were scaled to the dry mass of leaves and flowers contained in the enclosure. Only flower dry mass was accounted for crabapple emis-sion rates as leaves appeared at the end of the flowering pe-riod. Total normalized (30 • C) monoterpene emissions from honey locust were higher during flowering (5.3 µgC g −1 h −1) than after flowering (1.2 µgC g −1 h −1). The total normal-ized BVOC emission rate from crabapple (93 µgC g −1 h −1) during the flowering period is of the same order as iso-prene emissions from oak trees, which are among the high-est BVOC flowering period floral emissions observed from plants to date. These findings illustrate that during the rela-tively brief springtime flowering period, floral emissions con-stitute by far the most significant contribution to the BVOC flux from these tree species, some of which are leafless at this time. Experimental results were integrated into the MEGAN biogenic emission model and simulations were performed to estimate the contribution of floral BVOC emissions to the to-tal urban BVOC flux during the spring flowering period. The floral BVOC emitted during this three-month simulation are equivalent to 11 % of the integrated monoterpene flux for the Boulder urban area.
It is well known that urban trees produce various types of benefits and costs. The computer tool i-Tree STRATUM helps quantify tree structure and function, as well as the value of some of these tree services in different municipalities. This study describes one of the first applications of STRATUM outside the U.S. Lisbon's street trees are dominated by Celtis australis L., Tilia spp., and Jacaranda mimosifolia D. Don, which together account for 40% of the 41,247 trees. These trees provide services valued at $8.4 million annually, while $1.9 million is spent in their maintenance. For every $1 invested in tree management, residents receive $4.48 in benefits. The value of energy savings ($6.20/tree), CO2 reduction ($0.33/tree) and air pollutant deposition ($5.40/tree) were comparable to several other U.S. cities. The large values associated with stormwater runoff reduction ($47.80/tree) and increased real estate value ($144.70/tree) were substantially greater than values obtained in U.S. cities. Unique aspects of Lisbon's urban morphology and improvement programs are partially responsible for these differences.
The Ozarks Isoprene Experiment (OZIE) was conducted in July 1998 in Missouri, Illinois, Indiana, and Oklahoma. OZIE was designed to investigate the presumed strong isoprene emission rates from the Missouri Ozarks, where there is a high density of oak trees that are efficient isoprene emitters. Ground, balloon, and aircraft measurements were taken over a three-week study period; 0-D and 3-D chemical models were subsequently used to better understand the observed isoprene emissions from the Ozarks and to investigate their potential regional-scale impacts. Leaf-level measurements for two oak tree species yielded normalized average isoprene emission capacities of 66 mgC g(-1) h(-1), in good agreement with values used in current biogenic emissions models. However, the emission capacities exhibited a temperature dependence that is not captured by commonly used biogenic emission models. Isoprene mixing ratios measured aloft from tethered balloon systems were used to estimate isoprene fluxes. These measurement-derived fluxes agreed with BEIS3 estimates within the relatively large uncertainties in the estimates. Ground-level isoprene mixing ratios exhibited substantial spatial heterogeneity, ranging from <1 to 35 ppbv. The agreement between measured isoprene mixing ratios and regional-scale chemical transport model estimates was improved upon averaging the ground-level isoprene data observed at several sites within a representative area. Ground-level formaldehyde (HCHO) mixing ratios were very high (up to 20 ppbv) and were consistently higher than mixing ratios predicted by a regional chemical transport model. The spatial distribution and magnitude of the elevated HCHO concentrations showed good agreement with GOME satellite column observations of HCHO.
Variability in the emission rates of isoprene and monoterpenes from individual leaves of Eucalyptus globulus was investigated with a laboratory gas exchange system and an environmental control leaf cuvette. For individual leaves, with constant environmental conditions, short-term (I hour) fluctuations in isoprene emission rates were less than 3% while day-to-day fluctuations averaged 14%. Leaf-to-leaf variations were much larger (62%). Fluctuations with time and leaf-to-leaf variability in CO2 assimilation rates were of the same order as isoprene, while monoterpene variations were higher. Leaf age was identified as one of the factors contributing to leaf-to-leaf variability in CO2 assimilation and isoprene and monoterpene emission rates. Monoterpene emission rates were not influenced by light intensity or CO2 mixing ratio. The observed temperature dependence was the same for alpha-pinene and 1,8-cineole (an oxygenated monoterpene) and is similar to the temperature dependence of monoterpene emission rates reported by other investigators. Isoprene emissions were slightly dependent on humidity (1-3% increase in emission per 10% increase in relative humidity) and responded only to very low (< 100 ppm) or very high (> 600 PPM) CO2 mixing ratios. Isoprene emission was associated with the abaxial leaf side, which contains stomatal pores, while monoterpenes were emitted primarily from the adaxial side, which lacks stomatal pores. The temperature and light dependence of isoprene emission closely resembles relationships observed for electron transport in plant chloroplasts. For this reason, we have used a mechanistic electron transport model as the basis for an empirical isoprene emission rate model. The emission rate variation predicted by this model was within 10% of observed values for 62% of the 255 observations at light-saturated conditions and temperatures between 23-degrees and 33-degrees-C. The entire data base includes over 600 observations at leaf temperatures ranging between 12-degrees and 50-degrees-C and light intensities between 0 and 2000-mu-mol m-2 s-1. Nearly two thirds of the emission rates predicted for the entire data base were within a factor of 1.25, and 89% were within a factor of 2. The algorithms developed in this study provide a solid physiological basis for future efforts to model the biogenic flux of isoprene and monoterpenes into the atmosphere.
The emission of isoprene and monoterpenes from plants is influenced by light and leaf temperature, which account for almost all short-term variations (minutes to days) and a large part of spatial and long-term variations. The temperature dependence of monoterpene emission varies among monoterpenes, plant species, and other factors, but a simple exponential relationship between emission rate (E) and leaf temperature (T), E = E(s) [exp (beta(T - T(s)))], provides a good approximation. A review of reported measurements suggests a best estimate of beta = 0.09 K-1 for all plants and monoterpenes. Isoprene emissions increase with photosynthetically active radiation up to a saturation point at 700-900 mumol m-2 s-1. An exponential increase in isoprene emission is observed at leaf temperatures of less than 30-degrees-C. Emissions continue to increase with higher temperatures until a maximum emission rate is reached at about 40-degrees-C, after which emissions rapidly decline. This temperature dependence can be described by an enzyme activation equation that includes denaturation at high temperature. Algorithms developed to simulate these light and temperature responses perform well for a variety of plant species under laboratory and field conditions. Evaluations with field measurements indicate that these algorithms perform significantly better than earlier models which have previously been used to simulate isoprene emission rate variation. These algorithms account for about 90% of observed diurnal variability and can predict diurnal variations in hourly averaged isoprene emissions to within 35%.
Reactive gases and aerosols are produced by terrestrial ecosystems, processed within plant canopies, and can then be emitted into the above-canopy atmosphere. Estimates of the above-canopy fluxes are needed for quantitative earth system studies and assessments of past, present and future air quality and climate. The Model of Emissions of Gases and Aerosols from Nature (MEGAN) is described and used to quantify net terrestrial biosphere emission of isoprene into the atmosphere. MEGAN is designed for both global and regional emission modeling and has global coverage with similar to 1 km(2) spatial resolution. Field and laboratory investigations of the processes controlling isoprene emission are described and data available for model development and evaluation are summarized. The factors controlling isoprene emissions include biological, physical and chemical driving variables. MEGAN driving variables are derived from models and satellite and ground observations. Tropical broadleaf trees contribute almost half of the estimated global annual isoprene emission due to their relatively high emission factors and because they are often exposed to conditions that are conducive for isoprene emission. The remaining flux is primarily from shrubs which have a widespread distribution. The annual global isoprene emission estimated with MEGAN ranges from about 500 to 750 Tg isoprene ( 440 to 660 Tg carbon) depending on the driving variables which include temperature, solar radiation, Leaf Area Index, and plant functional type. The global annual isoprene emission estimated using the standard driving variables is similar to 600 Tg isoprene. Differences in driving variables result in emission estimates that differ by more than a factor of three for specific times and locations. It is difficult to evaluate isoprene emission estimates using the concentration distributions simulated using chemistry and transport models, due to the substantial uncertainties in other model components, but at least some global models produce reasonable results when using isoprene emission distributions similar to MEGAN estimates. In addition, comparison with isoprene emissions estimated from satellite formaldehyde observations indicates reasonable agreement. The sensitivity of isoprene emissions to earth system changes ( e. g., climate and land-use) demonstrates the potential for large future changes in emissions. Using temperature distributions simulated by global climate models for year 2100, MEGAN estimates that isoprene emissions increase by more than a factor of two. This is considerably greater than previous estimates and additional observations are needed to evaluate and improve the methods used to predict future isoprene emissions.
Numerical assessments of global air quality and potential changes in atmospheric chemical constituents require estimates of the surface fluxes of a variety of trace gas species. We have developed a global model to estimate emissions of volatile organic compounds from natural sources (NVOC). Methane is not considered here and has been reviewed in detail elsewhere. The model has a highly resolved spatial grid (0.5 degrees x 0.5 degrees latitude/longitude) and generates hourly average emission estimates. Chemical species are grouped into four categories: isoprene, monoterpenes, other reactive VOC (ORVOC), and other VOC (OVOC). NVOC emissions from oceans are estimated as a function of geophysical variables from a general circulation model and ocean color satellite data. Emissions from plant foliage are estimated from ecosystem specific biomass and emission factors and algorithms describing light and temperature dependence of NVOC emissions. Foliar density estimates are based on climatic variables and satellite data. Temporal variations in the model are driven by monthly estimates of biomass and temperature and hourly light estimates. The annual global VOC flux is estimated to be 1150 Tg C, composed of 44% isoprene, 11% monoterpenes, 22.5% other reactive VOC, and 22.5% other VOC. Large uncertainties exist for each of these estimates and particularly for compounds other than isoprene and monoterpenes. Tropical woodlands (rain forest, seasonal, drought-deciduous, and savanna) contribute about half of all global natural VOC emissions. Croplands, shrublands and other woodlands contribute 10-20% apiece. Isoprene emissions calculated for temperate regions are as much as a factor of 5 higher than previous estimates.
Isoprene emission capacity measurements are presented from 18 North American oak (Quercus) species and species from six other genera previously found to emit significant quantities of isoprene. Sampling was conducted at physiographically diverse locations in North Carolina, Central California, and Northern Oregon. Emissions from several sun leaves of each species were measured at or near standard conditions (leaf temperature of 30 degreesC and photosynthetically active radiation of 1000 mu mol m(-2) s(-1)) using environmentally controlled cuvette systems and gas chromatography with reduction gas detectors. Species mean emission capacity ranged from 39 to 158 mug C g(-1) h(-1) (mean of 86), or 22 to 79 nmol m(-2) s(-1) (mean of 44). These rates are 2-28 times higher than those previously reported from the same species, which were summarized in a recent study where isoprene emission rates were assigned based on published data and taxonomy. These discrepancies were attributed to differences in leaf environment during development, measurement technique (branch or plant enclosure versus leaf enclosure), and lack of environmental measurements associated with some of the earlier branch enclosure measurements. Mass-based emission capacities for 15 of 18 oak species. sweetgum (Liquidambar styraciflua), and poplars (Populus trichocarpa and P. deltoides) were within ranges used in current biogenic volatile organic compound (BVOC) emission models, while measured rates for the remaining three oak species, Nyssa sylvatica, Platanus occidentalis. Robinia pseudoacacia, Salix nigra, and Populus hybrids (Populus trichocarpa x P. deltoides) were considerably higher. In addition, mean specific leaf mass of the oak species was 30% higher than assumed in current emission models. Emission rates reported here and in other recent studies support recent conclusions that isoprene emission capacities for sun leaves of high emitting species may be better represented by a value of 100 +/- 50 mug C g(-1) h(-1) during hot summer conditions. We also find that intermediate isoprene emission rates previously suggested for some tree species may not represent their true emission capacities, and that broadleaf plant species may have either low (< 1.0 mug C g(-1) h(-1)) or very high (similar to 100 mug C g(-1) h(-1)) genetic capacity to emit isoprene when mature foliage is exposed to a high ambient temperature and light environment. Published by Elsevier Science Ltd.
This overview compiles the actual knowledge of the biogenic emissions of some volatile organic compounds (VOCs), i.e., isoprene, terpenes, alkanes, alkenes, alcohols, esters, carbonyls, and acids. We discuss VOC biosynthesis, emission inventories, relations between emission and plant physiology as well as temperature and radiation, and ecophysiological functions. For isoprene and monoterpenes, an extended summary of standard emission factors, with data related to the plant genus and species, is included. The data compilation shows that we have quite a substantial knowledge of the emission of isoprene and monoterpenes, including emission rates, emission regulation, and biosynthesis. The situation is worse in the case of numerous other compounds (other VOCs or OVOCs) being emitted by the biosphere. This is reflected in the insufficient knowledge of emission rates and biological functions. Except for the terpenoids, only a limited number of studies of OVOCs are available; data are summarized for alkanes, alkenes, carbonyls, alcohols, acids, and esters. In addition to closing these gaps of knowledge, one of the major objectives for future VOC research is improving our knowledge of the fate of organic carbon in the atmosphere, ending up in oxidation products and/or as aerosol particles.
Vehicle emissions of VOCs were determined in summer and winter of 2003 at the Shing Mun Tunnel, Hong Kong. One hundred and ten VOCs were quantified in this study. The average concentration of the total measured VOCs at the inlet and outlet of the tunnel were 81 250 pptv and 117 850 pptv, respectively. Among the 110 compounds analyzed, ethene, ethyne and toluene were the most abundant species in the tunnel. The total measured VOC emission factors ranged from 67 mg veh−1 km−1 to 148 mg veh−1 km−1, with an average of 115 mg veh−1 km−1. The five most abundant VOCs observed in the tunnel were, in decreasing order, ethene, toluene, n-butane, propane and i-pentane. These five most abundant species contributed over 38% of the total measured VOCs emitted. The high propane and n-butane emissions were found to be associated with LPG-fueled taxi. And fair correlations were observed between marker species (ethene, i-pentane, n-nonane, BTEX) with fractions of gasoline-fueled or diesel-fueled vehicles. Moreover, ethene, ethyne, and propene are the key species that were abundant in the tunnel but not in gasoline vapors or LPG. In order to evaluate the ozone formation potential emissions in Hong Kong, the maximum increment reactivity is calculated. It was found that about 568 mg of O3 is induced by per vehicle per kilometer traveled. Among them, ethene, propene and toluene contribute most to the ozone-formation reactivity.
We present a new European plant-specific emission inventory for isoprene, monoterpenes, sesquiterpenes and oxygenated VOC (OVOC), on a spatial resolution of 0.089×0.089 degrees, for implementation in atmospheric transport models. The inventory incorporates more accurate data on foliar biomass densities from several litterfall databases that became available in the last years for the main tree species in Europe. A bioclimatic correction factor was introduced to correct the foliar biomass densities of trees and crops for the different plant growth conditions that can be found in Pan-Europe. Long-term seasonal variability of agriculture and forest emissions was taken into account by implementing a new growing season concept. The 2004–2005 averaged annual total biogenic volatile organic compound (BVOC) emissions for the Pan-European domain are estimated to be about 12 Tg with a large contribution from the OVOC class of about 4.5 Tg and from monoterpenes of about 4 Tg. Annual isoprene emissions are found to be about 3.5 Tg, insensitive to the chosen emission algorithm. Emissions of OVOC were found to originate to a large extent from agriculture. Further experiments on crop emissions should be carried out to check the validity of the applied standard emission factors. The new inventory aims at a fully transparent and verifiable aggregation of detailed land use information and at the inclusion of plant-specific emission data. Though plant-specific land use data is available with relatively high accuracy, a lack of experimental biomass densities and emission data on terpenes, sesquiterpenes and oxygenated VOC, in particular for agricultural plants, currently limits the setup of a highly accurate plant-specific emission inventory.
A biogenic emissions scheme has been incorporated in the global dynamic vegetation model ORCHIDEE (Organizing Carbon and Hydrology in Dynamic EcosystEms) in order to calculate global biogenic emissions of isoprene, monoterpenes, methanol, acetone, acetaldehyde, formaldehyde and formic and acetic acids. Important parameters such as the leaf area index are fully determined by the global vegetation model and the influences of light extinction (for isoprene emissions) and leaf age (for isoprene and methanol emissions) are also taken into account. We study the interannual variability of biogenic emissions using the satellite-based climate forcing ISLSCP-II as well as relevant CO<sub>2</sub> atmospheric levels, for the 1983–1995 period. Mean global emissions of 460 TgC/yr for isoprene, 117 TgC/yr for monoterpenes, 106 TgC/yr for methanol and 42 TgC/yr for acetone are predicted. The mean global emission of all biogenic compounds is 752±16 TgC/yr with extremes ranging from 717 TgC/yr in 1986 to 778 TgC/yr in 1995, that is a 8.5% increase between both. This variability differs significantly from one region to another and among the regions studied, biogenic emissions anomalies were the most variable in Europe and the least variable in Indonesia (isoprene and monoterpenes) and North America (methanol). Two scenarios of land use changes are considered using the 1983 climate and atmospheric CO<sub>2</sub> conditions, to study the sensitivity of biogenic emissions to vegetation alteration, namely tropical deforestation and European afforestation. Global biogenic emissions are highly affected by tropical deforestation, with a 29% decrease in isoprene emission and a 22% increase in methanol emission. Global emissions are not significantly affected by European afforestation, but on a European scale, total biogenic VOCs emissions increase by 54%.
Data taken in aircraft transects of emissions plumes from rural U.S. coal-fired power plants were used to confirm and quantify the nonlinear dependence of tropospheric ozone formation on plume NO(x) (NO plus NO(2)) concentration, which is determined by plant NO(x) emission rate and atmospheric dispersion. The ambient availability of reactive volatile organic compounds, principally biogenic isoprene, was also found to modulate ozone production rate and yield in these rural plumes. Differences of a factor of 2 or greater in plume ozone formation rates and yields as a function of NO(x) and volatile organic compound concentrations were consistently observed. These large differences suggest that consideration of power plant NO(x) emission rates and geographic locations in current and future U.S. ozone control strategies could substantially enhance the efficacy of NO(x) reductions from these sources.
The atmospheric hydrocarbon budget is important for predicting ozone episodes and the effects of pollution mitigation strategies. Isoprene emission from plants is an important part of the atmospheric hydrocarbon budget. We measured isoprene emission capacity at the bottom, middle, and top of the canopies of a white oak (Quercus alba L.) tree and a red oak (Quercus rubra L.) tree growing adjacent to a tower in the Duke University Forest. Leaves at the top of the white oak tree canopy had a three- to fivefold greater capacity for emitting isoprene than leaves at the bottom of the tree canopy. Isoprene emission rate increased with increasing temperature up to about 42 degrees C. We conclude that leaves at the top of the white oak tree canopy had higher isoprene emission rates because they were exposed to more sunlight, reduced water availability, and higher temperature than leaves at the bottom of the canopy. Between 35 and 40 degrees C, white oak photosynthesis and stomatal conductance declined, whereas red oak (Quercus rubra) photosynthesis and stomatal conductance increased over this range. Red oak had lower rates of isoprene emission than white oak, perhaps reflecting the higher stomatal conductance that would keep leaves cool. The concentration of isoprene inside the leaf was estimated with a simplified form of the equation used to estimate CO(2) inside leaves.
This chapter focuses on the global distributions of the C2 to C10 nonmethane hydrocarbons (NMHCs) and derived light oxygenated species. Due to relatively large areas, where no data are available, and the high reactivity of these compounds, leading to scattered data, global latitudinal and seasonal distributions can be well described only for species, such as ethane, propane, and acetylene, with lifetimes on the order of several weeks or months. These distributions reveal, at ground level as well as in the free troposphere, a clear strong interhemispheric gradient, with ambient concentrations, at mid-northern latitudes, one to two orders of higher magnitude than in the Southern Hemisphere. The seasonality of the species distributions is due to the variability of both their sources and their major atmospheric sink (OH radicals). This leads, in the Northern Hemisphere, to maximum concentrations during winter. In addition, the species distributions reveal the influence of long-range transport of species from nonlocal sources to Arctic or inhabited area. These species can thus be used as tracers for specific sources. The situation is much more complex for more reactive species such as higher (> C4) alkanes or alkenes, and biogenic NMHCs. In the free troposphere high concentrations of even highly reactive NMHCs have been reported. Although the sources of biogenic compounds are believed to be dominant among the reactive volatile organic compound budgets, their high reactivity and the strong dependence of their sources on photosynthesis processes lead to a tremendous variability in their ambient concentrations.
The Sacramento Municipal Utility District's (SMUD) shade tree program will result in the planting of 500,000 trees and has been found to produce net benefits from air conditioning savings. In this study we assume three scenarios (base, highest, and lowest benefits) based on the SMUD program and apply Best Available Control Technology (BACT) cost analysis to determine if shade trees planted in residential yards can be a cost effective means to improve air quality. Planting and maintenance costs, pollutant deposition, and biogenic hydrocarbon emissions are estimated annually for 30 years with existing deterministic models. For the base case, the average annual dollar benefit of pollutant uptake was $895 and the cost of biogenic hydrocarbon emissions was $512, for a net pollutant uptake benefit of $383 per 100 trees planted. The uniform annual payment necessary to repay planting and maintenance costs with a 10% rate of interest was $749. When high biogenic hydrocarbon emitting tree species were replaced with low-emitters, the base case benefit-cost ratio (BCR) increased from 0.5: 1 to 0.9: l. The BCR for the “highest” and “lowest” benefit cases were 2.2:1 and −0.8:1, respectively. Although SMUD plantings produce cost effective energy savings, our application of the BACT analysis does not suggest convincing evidence that there is cost savings when only air quality benefits are considered.