Article

Removal of benzene from indoor air by Dracaena sanderiana: Effect of wax and stomata

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Abstract

From screening 8 ornamental plants, it was found that Dracaena sanderiana had the highest benzene removal efficiency. In a long-term study, 4 cycles of benzene were studied under both 24 h dark and 24 h light conditions. From the 2nd to 4th cycle, benzene uptake by plants under 24 h light condition had higher intensity than under 24 h dark conditions, and the close of D. sanderiana stomata was found only in 24 h dark condition. At the final cycle, D. sanderiana still survived, and benzene uptake continued. From the calculation, 46% of benzene was taken up by D. sanderiana crude wax, while 54% was predicted to be taken up by the stomata by 72 h.

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... Therefore, root parts were covered by aluminum foil. The surface area of leaves was selected around 130-150 cm 2 for each plant (Treesubsuntorn and Thiravetyan, 2012;Boraphech and Thiravetyan, 2015). ...
... Two plants (Prickly pear cactus, and C. hexagonus (L.) Mill.) with high amounts of wax in the leaves had the highest TMA removal efficiency. It was consistent with the study by Treesubsuntorn et al. (2012) who reported that 46% of total benzene uptake was by crude wax of D. sanderiana Sander at 72 h. The results suggested that the crude wax could act as a biosorbent. ...
... The results suggested that the crude wax could act as a biosorbent. The crude wax can be one important factor for adsorbing air pollutants (Treesubsuntorn and Thiravetyan, 2012). Moreover, a previous study from Treesubsuntorn et al. (2015) suggested that not only the quantity of wax but also the composition of wax affects pollutant adsorption. ...
... In view of phytoremediation, studies show that the openings (cuticle and stomata) of plant bodies are responsible for potential VOC uptake, predominantly via stomata during the daytime when the stomata are open, unless it is a CAM plant (Weyens et al., 2015). Additionally, the occupied amount of VOCs on the waxy layer determine the potential of cuticular absorption (Treesubsuntorn and Thiravetyan, 2012;Sriprapat and Thiravertyan 2013). Once inserted into the plant system, either the VOCs undergo sequential degradation through the plant itself thereby transforming them into harmless constituents or the excretion and storage method in case degradation fails to occur (Weyens et al., 2015). ...
... Through the efficacy of phytoremediation based on plants' species specificity and pollutants' characteristics (Papinchak et al., 2009), it may easily provide a low-cost, energy-efficient, self-regulating, potential green replacement Luengas et al., 2015;Pettit et al., 2018a) either by active (green roof, green walls, bio-covers) or passive (potted plants and their association with microorganisms) approaches. There are several well-reported ornamental plants that are involved in abatement of particular air pollutions like Dracaena sanderiana (Treesubsuntorn and Thiravetyan, 2012), Schefflera arboricola, and Spathiphyllum wallisii (Parseh et al., 2018) for benzene; Schefflera actinophylla for xylene and toluene (Kim et al., 2016); Dieffenbachia compacta (Aydogan and Montoya, 2011) and Chamaedorea elegans (Teiri et al., 2020) for fomaldehyde; Chlorophytum comosum, Dracaena deremensis, and for trichloroethylene, benzene, and formaldehyde (Wolverton et al., 1989); and Dypsis lutescens for total volatile organic compounds, CO 2 , and CO (Bhargava et al., 2021). The initial idea that green systems can effectively ameliorate high levels of indoor air pollutants was investigated from space science research in order to evolve a spacecraft that is self-sustaining by utilising a biological life support system (Salisbury et al., 1997;Andre and Chagvardieff, 1997). ...
... The potted plants enable the decomposition of VOCs and were reported to reduce benzene by 15% (Lim et al., 2009). Nonetheless, to observe the VOC removal capacity of aerial parts, in a few experiments the aboveground part of the plant was subjected to a physical barrier and isolated from the rest of the substrate, along with the root zone, which showed a positive response independently (Tani et al., 2007;Tani and Hewitt, 2009;Treesubsuntorn and Thiravetyan, 2012;Treesubsuntorn et al., 2013;Sriprapat and Thiravertyan, 2013;Sriprapat et al., 2014a, b). Aydogan and Montoya (2011) set an experiment to observe the efficiency of the formaldehyde-removal capacity of plant root zones and aerial parts separately. ...
... In addition, wood-based panel products commonly used in the residential unit are the main sources of VOCs, especially particleboards emitting halogenated compounds, ester, and aromatic hydrocarbons . Even though VOCs can be oxidized by UV light or sunlight, the indoor conditions have low light intensity, which may not be adequate to oxidize these compounds (Talhout et al. 2011;Treesubsuntorn and Thiravetyan 2012). In addition, poor air ventilation is generally the main problem for indoor pollutant accumulation since ventilation can help dilute pollutant concentrations by bringing in fresh outdoor air (Treesubsuntorn and Thiravetyan 2012). ...
... Even though VOCs can be oxidized by UV light or sunlight, the indoor conditions have low light intensity, which may not be adequate to oxidize these compounds (Talhout et al. 2011;Treesubsuntorn and Thiravetyan 2012). In addition, poor air ventilation is generally the main problem for indoor pollutant accumulation since ventilation can help dilute pollutant concentrations by bringing in fresh outdoor air (Treesubsuntorn and Thiravetyan 2012). Cavalcante et al. (2006) indicated that the indoor level of carbonyl compounds (CCs) is higher than outdoor affecting increasing of cancer risk in indoor air. ...
... Many studies report the accumulation of several pollutants indoors such as benzene, toluene, ethylbenzene, xylene, and formaldehyde (Chikara et al. 2009). High BTEX, formaldehyde, ozone, and trimethylamine concentrations are frequently found in indoor conditions (Treesubsuntorn et al., 2012;Sriprapat and Thiravetyan 2013;Boraphech and Thiravetyan 2015;Chen et al. 2018;Li et al. 2019). Taking in these compounds in high concentration can affect human systems such as the nervous and respiratory systems. ...
Article
Full-text available
High-rise residential developments are rapidly increasing in urban areas. Smaller residential units in this high rise bring a reduction in windows, resulting in poor indoor air ventilation. In addition, materials used in interiors can emit volatile organic compounds (VOCs), which can significantly affect human health. Since people spend 90% of their time indoors, an evaluation of indoor air quality is especially important for high-rise residential buildings with an analysis of determining factors. This study aims to measure the concentrations of VOCs, formaldehyde, and particulate matter (PM2.5 and PM10) in 9 high-rise residential buildings in Bangkok by using the accidental sampling method (n = 252) and to investigate possible important determining factors. The results show that the average concentrations of VOCs, formaldehyde, PM2.5, and PM10 in 9 high-rise residential buildings were at good to moderate levels in the indoor air quality index (IAQI) and that high pollutant concentrations were rarely found except in new constructions. Moreover, it was found that the age of buildings shows strong correlations with all pollutants (p value < 0.0001). Old buildings showed significantly lower pollutant concentrations than new and under-construction buildings at a 95% confidence level. The findings from this investigation can be used as part of sustainable well-being design guidelines for future high-rise residential developments.
... Many factors impact the VOC removal efficiency of plants. Previous studies have indicated that light condition is an important factor for phytoremediation [18,19]. Some studies have reported that plant-associated microorganisms play an important role in removing indoor air pollutants [20,21]. ...
... Some studies have reported that plant-associated microorganisms play an important role in removing indoor air pollutants [20,21]. Sriprapat and Thiravetyan [18] reported that water stress has a negative effect on phytoremediation. Furthermore, chlorophyll concentration and enzyme systems are reported to be essential for plants in detoxifying hazardous organic compounds [18,22]. ...
... Sriprapat and Thiravetyan [18] reported that water stress has a negative effect on phytoremediation. Furthermore, chlorophyll concentration and enzyme systems are reported to be essential for plants in detoxifying hazardous organic compounds [18,22]. However, systematical analysis of influencing factors such as chlorophyll or peroxidase (POD) is scarce. ...
Article
Full-text available
The concentration of benzene in indoor air has received appreciable attention due to its adverse health effects. Although phytoremediation has been considered as an eco-friendly method to remove benzene, it is unclear how to select plants with a high removal rate. In this study, we evaluated the benzene removal efficiency of four common ornamental plants, Epipremnum aureum, Chlorophytum comosum, Hedera helix and Echinopsis tubiflora, and we also explored the factors impacting benzene removal efficiency. The removal efficiency of all plants in this study averaged at 72 percent. The benzene absorption rates of Epipremnum aureum, Hedera helix and Chlorophytum comosum were 1.10, 0.85 and 0.27 µg·m−3·cm−2, respectively. This is due to the different transpiration rates and chlorophyll concentrations in the plants. The benzene removal efficiency of crassulacean acid metabolism plant (Echinopsis tubiflora) was 23% higher than C3 plant (Epipremnum aureum) under dark conditions. This can be attributed to the fact that the characteristic of Echinopsis tubiflora stomata is different from Epipremnum aureum stomata, which is still open under dark conditions. Therefore, Echinopsis tubiflora can take up more benzene than Epipremnum aureum. For different initial benzene concentrations, the benzene removal efficiency of Echinopsis tubiflora was always great (50–80%), owing to its high rate of transpiration and concentration of chlorophyll. Our findings indicate that transpiration rate and chlorophyll concentration can be used as reference parameters to facilitate ornamental plant screening for indoor air quality improvement.
... Possibly due to the variances in conditions amongst different experiments such as the use of different plant species, VOCs, pollutant concentrations, chamber sizes and light levels (see Table 1), it is difficult to ascertain which components of the pottedplant system are responsible for VOC removal. Most of our understanding of the mechanisms of VOC removal is derived from experiments that have used aluminum foil or Teflon bags to isolate a particular part of the potted-plant microcosm (Aydogan and Montoya, 2011;Treesubsuntorn and Thiravetyan, 2012;Sriprapat et al., 2014a;Kim et al., 2016), or experiments that have assessed VOC removal under different lighting conditions (Porter, 1994;Kondo et al., 1995;Wood et al., 2002;Orwell et al., 2004;Yoo et al., 2006;Kim et al., 2008;Aydogan and Montoya, 2011;Xu et al., 2011;Treesubsuntorn and Thiravetyan, 2012;H€ ormann et al., 2018;Teiri et al., 2018), while several experiments have simply assessed VOC drawdown without testing removal mechanisms (Cornejo et al., 1999;Orwell et al., 2006;Liu et al., 2007;Yang et al., 2009;Kim et al., 2010Kim et al., , 2014Mosaddegh et al., 2014). A thorough understanding of the removal mechanism is crucial if these systems are to be optimized with the intention of enhancing the VOC removal rate. ...
... Possibly due to the variances in conditions amongst different experiments such as the use of different plant species, VOCs, pollutant concentrations, chamber sizes and light levels (see Table 1), it is difficult to ascertain which components of the pottedplant system are responsible for VOC removal. Most of our understanding of the mechanisms of VOC removal is derived from experiments that have used aluminum foil or Teflon bags to isolate a particular part of the potted-plant microcosm (Aydogan and Montoya, 2011;Treesubsuntorn and Thiravetyan, 2012;Sriprapat et al., 2014a;Kim et al., 2016), or experiments that have assessed VOC removal under different lighting conditions (Porter, 1994;Kondo et al., 1995;Wood et al., 2002;Orwell et al., 2004;Yoo et al., 2006;Kim et al., 2008;Aydogan and Montoya, 2011;Xu et al., 2011;Treesubsuntorn and Thiravetyan, 2012;H€ ormann et al., 2018;Teiri et al., 2018), while several experiments have simply assessed VOC drawdown without testing removal mechanisms (Cornejo et al., 1999;Orwell et al., 2006;Liu et al., 2007;Yang et al., 2009;Kim et al., 2010Kim et al., , 2014Mosaddegh et al., 2014). A thorough understanding of the removal mechanism is crucial if these systems are to be optimized with the intention of enhancing the VOC removal rate. ...
... Several experiments have compared VOC removal efficiencies under different lighting conditions (Porter, 1994;Kondo et al., 1995;Wood et al., 2002;Orwell et al., 2004;Yoo et al., 2006;Aydogan and Montoya, 2011;Xu et al., 2011;Treesubsuntorn and Thiravetyan, 2012;H€ ormann et al., 2018;Teiri et al., 2018). These experiments used light intensity as a surrogate for foliage uptake under the assumption that increased light intensity increases stomatal conductance and plant metabolic activity (Porter, 1994). ...
Article
Indoor air quality has become a growing concern due to the increasing proportion of time people spend indoors, combined with reduced building ventilation rates resulting from an increasing awareness of building energy use. It has been well established that potted-plants can help to phytoremediate a diverse range of indoor air pollutants. In particular, a substantial body of literature has demonstrated the ability of the potted-plant system to remove volatile organic compounds (VOCs) from indoor air. These findings have largely originated from laboratory scale chamber experiments, with several studies drawing different conclusions regarding the primary VOC removal mechanism, and removal efficiencies. Advancements in indoor air phytoremediation technology, notably active botanical biofilters, can more effectively reduce the concentrations of multiple indoor air pollutants through the action of active airflow through a plant growing medium, along with vertically aligned plants which achieve a high leaf area density per unit of floor space. Despite variable system designs, systems available have clear potential to assist or replace existing mechanical ventilation systems for indoor air pollutant removal. Further research is needed to develop, test and confirm their effectiveness and safety before they can be functionally integrated in the broader built environment. The current article reviews the current state of active air phytoremediation technology, discusses the available botanical biofiltration systems, and identifies areas in need of development.
... Reduction, compared to controls without plants or growth medium, was notably greater with the commercial Naava growth mix (Nmix) than with soil (Table S2). Such immediate VOC loss could be attributed to active uptake by plants, 2,[6][7][8]15,18 or to partitioning from the gaseous phase to moist surfaces of the plants and chambers or solid phases of the growth media. 8,15 The importance of the latter mechanism was supported by the observation that active circulation of air through growth medium and rhizosphere further improved the loss; potted plants with Nmix and a fan reduced the concentrations of all added VOCs to below the F I G U R E 2 Remaining VOC concentrations in small chambers containing neither plants nor growth medium (Control), or supplied with plants in soil or soilless growth medium with or without air circulation through rhizosphere. ...
... Such immediate VOC loss could be attributed to active uptake by plants, 2,[6][7][8]15,18 or to partitioning from the gaseous phase to moist surfaces of the plants and chambers or solid phases of the growth media. 8,15 The importance of the latter mechanism was supported by the observation that active circulation of air through growth medium and rhizosphere further improved the loss; potted plants with Nmix and a fan reduced the concentrations of all added VOCs to below the F I G U R E 2 Remaining VOC concentrations in small chambers containing neither plants nor growth medium (Control), or supplied with plants in soil or soilless growth medium with or without air circulation through rhizosphere. The bars show mean and standard deviation for each introduced VOC for 4-6 replicate chambers (pothos) or 3 replicate chambers (fern); see Tables S1, S2 for detailed statistical results detection limit in 20-21 hours (Figure 2; Table S2). ...
... BTEX compounds (monoaromates: benzene, toluene, ethylbenzene and xylene) and α-pinene as well as octane were removed more efficiently in chambers with plants at the beginning of the experiment (Figure 3, right panel; Figure S3; Tables S3, S4). This may be attributed either to active VOC uptake by plants, 2,7,8,15,18 or to plants inoculating a more active or better acclimatized degrader community into the growth medium and/or irrigation water. 2,22 As the number of units containing plants decreased below 3 (due to plant removal for destructive root sampling), the relative effectiveness of the chambers with plants decreased below the effectiveness of the chambers without plants (but which had a constant 7 units). ...
Article
Botanical air filtration is a promising technology for reducing indoor air contaminants, but the underlying mechanisms need better understanding. Here, we made a set of chamber fumigation experiments of up to 16 weeks duration, to study the filtration efficiencies for seven volatile organic compounds (VOCs; decane, toluene, 2‐ethylhexanol, α‐pinene, octane, benzene, xylene) and to monitor microbial dynamics in simulated green wall systems. Biofiltration functioned on sub‐ppm VOC levels without concentration‐dependence. Airflow through the growth medium was needed for efficient removal of chemically diverse VOCs, and the use of optimized commercial growth medium further improved the efficiency compared with soil and Leca granules. Experimental green wall simulations using these components were immediately effective, indicating that initial VOC removal was largely abiotic. Golden pothos plants had a small additional positive impact on VOC filtration and bacterial diversity in the green wall system. Proteobacteria dominated the microbiota of rhizosphere and irrigation water. Airborne VOCs shaped the microbial communities, enriching potential VOC utilizing bacteria (especially Nevskiaceae and Patulibacteraceae) in the irrigation water, where much of the VOC degradation capacity of the biofiltration systems resided. These results clearly show the benefits of active air circulation and optimized growth media in modern green wall systems. This article is protected by copyright. All rights reserved.
... There are several technologies applied for benzene removal, including the effective phytoremediation technology (Liu et al. 2007;Treesubsuntorn et al. 2013). For example, high benzene removal efficiency was observed by Dracaena sanderiana (Treesubsuntorn and Thiravetyan 2012). However, in high toxic pollution levels, phytoremediation is limited and high number of plant was required (Taghavi et al. 2005). ...
... Fumigatory chamber was installed under temperature (~32°C) and pressure (~760 mmHg). Five microliters of 99.8% benzene, Panreac (made in E.U.), was injected into fumigatory chamber to obtain a benzene concentration of 348 mg/m 3 (Treesubsuntorn and Thiravetyan 2012;Treesubsuntorn et al. 2013). After 48 h of fumigation, microorganisms on the leaf surface of D. sanderiana were swabbed and incubated in nutrient broth (NB) at 30°C in 150 rpm checker for 24 h. ...
... One and 5 μL of liquid benzene were injected into the chamber to create benzene at initial concentrations of 70 and 348 mg/m 3 , respectively. Based on the previous study, 4 h was required for benzene equilibrium in fumigatory chamber (Treesubsuntorn and Thiravetyan 2012;Treesubsuntorn et al. 2013), and gas samples were collected every day. The experiment was operated 4 days for 70 mg/m 3 and 10 days for 348 mg/m 3 benzene. ...
Article
Full-text available
Benzene-tolerant phyllosphere microorganisms isolated from Dracaena sanderiana were identified as Pantoea sp. B11 and Staphylococcus sp. B12. Inoculating D. sanderiana with these microorganisms growing under 70 and 348 mg/m³ of airborne benzene showed a higher benzene removal efficiency than D. sanderiana without inoculation. Under 348 mg/m³ of benzene, inoculating D. sanderiana with Staphylococcus sp. B12 can remove benzene higher than inoculating D. sanderiana with Pantoea sp. B11 and co-culture between Staphylococcus sp. B12 and Pantoea sp. B11. In addition, individual Staphylococcus sp. B12 had higher ability to bio-remediate benzene than individual Pantoea sp. B11 and co-culture. Staphylococcus sp. B12 can also produce high indole-3-acetic acid (IAA) and harbor 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, which can protect plant from the stress. Photosystem II activity and chlorophyll content of D. sanderiana were decreased clearly under exposure with a 348 mg/m³ of benzene. Inoculating D. sanderiana with Staphylococcus sp. B12 had significantly higher photosystem II activity and chlorophyll content than inoculating D. sanderiana with Pantoea sp. B11 and co-cultures. In co-culture inoculation, Pantoea sp. B11 inhibited growth of Staphylococcus sp. B12, which can probably decrease benzene removal efficiency. Application of Staphylococcus sp. B12 can enhance benzene phytoremediation efficiency in D. sanderiana and protect plant from benzene stress.
... Many plant species have presented high VOC removal efficiency. 13,[22][23][24][25][26] In addition, plants have the ability to transform carbon-based air pollution and use it as a carbon source for plant growth. [27][28][29][30][31] Some native and nonnative microorganisms growing on plants can promote significant VOC removal efficiency. ...
... Since 2012, many plant species have been reported to have the ability to uptake benzene under light and dark conditions, where stomata under dark conditions should be closed in most of the plant. 22 However, some plant species can still highly take up air pollution under dark conditions. This suggested that plants can uptake air pollution via cuticular wax on shoot and leaf surfaces. ...
... D. sanderiana had the highest benzene removal efficiency, and can remove around 80% of 20 ppm gaseous benzene after exposed the pollutant in a closed system for 3 days. 22 In addition, stomata were proposed as a main benzene uptake pathway in this study. In 2013, Zamioculcas zamiifolia was reported as a high BTEX removal efficiency plant. ...
Conference Paper
Developing countries rapidly grow when green technology, which is referred to as eco-friendly processes or methods, is developed in parallel. Here, some examples of green technology research and development in Thailand will be overviewed. A huge amount of agricultural waste is generated during agricultural processes. Applying these agricultural wastes in order to maximize the benefits for environmental cleanups of water, soil and air has been studied and commercialized. For example: 1) Application of agricultural waste and/or biochar developed from agricultural waste as biological adsorbents for wastewater treatment in some industries, such as textile/dye industries, and printing industries. In addition, this agricultural waste can also be applied in decolorization of sugar syrup from sugar industries; 2) The research on modified biomaterials as adsorbents and packing materials in biofilters would also be presented, and now, pilot scale biofilters have been developed and applied to solve air pollution problems in the field for future commercialization; 3) Some agricultural waste and/or biochar developed from agricultural waste in our laboratory can promote rice growth and improve rice quality via the reduction of Cd uptake and translocation in rice. Phytoremediation technology, in which plants are used to improve the environmental quality in water and air, has also been studied and would be presented. 1) Some species of native Thai plants can effectively remove heavy metals and dye from wastewater. For this research, a constructed wetland for wastewater treatment was developed and applied in a real contaminated site. 2) In air phytoremediation, some plant species harbor highly volatile organic compound (VOC) removal efficiency. In addition, plants do not only absorb organic pollutants, but also they have the innate ability to degrade organic compounds and use them as carbon sources for their growth. In addition, plant growth-promoting (PGP) bacteria inoculation into plants can enhance airborne pollutant removal. From this research, an indoor air phytoremediation system was developed in order to reduce CO2 emissions with high VOC removal efficiency. The high cost of technology transfer is a major problem, especially in developing countries, and green technology research and innovation can overcome this problem along with efficient allocation of resources and technologies.
... Although the stomata were closed during drought conditions, the increased VOC removal may be attributed to the presence or increase in wax on the leaf surface [13,14]. Briefly, the quantity and composition of wax can influence VOC removal during the closed stomata as reported in the previous studies [15,16]. In contrast, the pattern of CO 2 RE varied with that of PM2.5 and VOCs. ...
... The accumulated RE of VOCs observed a similar trend as that of PM2.5. Although drought conditions revealed closed stomata, the higher VOCs removal may likely be due to the presence or increase of wax on the leaf surface; previous studies have reported the removal of benzene using wax [15,16]. ...
Article
Full-text available
Particulate matter has been increasing worldwide causing air pollution and serious health hazards. Owing to increased time spent indoors and lifestyle changes, assessing indoor air quality has become crucial. This study investigated the effect of watering and drought and illumination conditions (constant light, light/dark cycle, and constant dark) on particulate matter2.5 (PM2.5) removal and surface characterization of leaf in a botanical plant-based biofilter system. Using Ardisia japonica and Hedera helix as experimental plants in the plant-based biofilter system, PM2.5, volatile organic carbon, and CO2, as the evaluators of indoor air quality, were estimated using a sensor. Morphological and chemical changes of the leaf surface (i.e., roughness and wax) associated with PM2.5 removal were characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy. The highest PM2.5 removal efficiency, stomata closure, high leaf roughness, and wax layer were observed under drought with constant light condition. Consequently, PM2.5 removal was attributed to the combined effect of leaf roughness and wax by adsorption rather than stomatal uptake. These results suggest that operating conditions of indoor plant-based biofilter system such as watering (or drought) and illumination may be applied as a potential strategy for enhancing PM2.5 removal.
... Wolverton et al. (Wolverton and Wolverton 1993) subsequently conducted screening chamber studies of the VOC removal ability of 50 indoor plant species, with all plants tested demonstrating the capacity to reduce VOC concentrations. Results from additional studies showed that potted plants had the ability to also reduce levels of ammonia, nitrous oxides and particulate matter (Dela Cruz et al. 2014a, b;Gawrońska and Bakera 2015;Irga et al. 2013;Kim et al. 2008;Liu et al. 2007;Llewellyn and Dixon 2011;Treesubsuntorn and Thiravetyan 2012;Xu et al. 2011;Yoo et al. 2006). Subsequently, this work gained recognition for its potential value within the built environment on Earth, as buildings became more sealed from the 1970s onwards, as previously described (AIRAH 2016). ...
... Inoculating Azalea indica with toluene-degrading Pseudomonas putida has been shown to increase the rate of toluene removal (De Kempeneer et al. 2004). Treesubsuntorn and Thiravetyan (2012) identified microorganisms associated with trimethylamine (TMA) removal from plant rhizospheres, as subsequently bioaugmentated plants in closed system with the identified species, leading to enhanced rates of TMA gas remediation. Zhang et al. (2013) identification of rhizospheric bacteria that were positive for the toluene monooxygenase gene further supported the value of the rhizosphere microbial community in the phytoremediation capacity of indoor foliage plants (Chun et al. 2010;Zhang et al. 2013). ...
Article
Full-text available
Poor indoor air quality is a health problem of escalating magnitude, as communities become increasingly urbanised and people’s behaviours change, lending to lives spent almost exclusively in indoor environments. The accumulation of, and continued exposure to, indoor air pollution has been shown to result in detrimental health outcomes. Particulate matter penetrating into the building, volatile organic compounds (VOCs) outgassing from synthetic materials and carbon dioxide from human respiration are the main contributors to these indoor air quality concerns. Whilst a range of physiochemical methods have been developed to remove contaminants from indoor air, all methods have high maintenance costs. Despite many years of study and substantial market demand, a well evidenced procedure for indoor air bioremediation for all applications is yet to be developed. This review presents the main aspects of using horticultural biotechnological tools for improving indoor air quality, and explores the history of the technology, from the humble potted plant through to active botanical biofiltration. Regarding the procedure of air purification by potted plants, many researchers and decades of work have confirmed that the plants remove CO2 through photosynthesis, degrade VOCs through the metabolic action of rhizospheric microbes, and can sequester particulate matter through a range of physical mechanisms. These benefits notwithstanding, there are practical barriers reducing the value of potted plants as standalone air cleaning devices. Recent technological advancements have led to the development of active botanical biofilters, or functional green walls, which are becoming increasingly efficient and have the potential for the functional mitigation of indoor air pollutant concentrations. © 2018 Springer Science+Business Media B.V., part of Springer Nature
... With the development of society and the transformation of lifestyles, indoor air quality is garnering increasing amounts of attention as people spend more than 90% of their time indoors each day (Treesubsuntorn and Thiravetyan 2012;Cruz et al. 2014). Although the awareness of the human health impacts of exposure to air pollution growing rapidly (Caplin et al. 2019), indoor air quality is undergoing deterioration. ...
... Both hydrophilic and hydrophobic pollutants can adhere to the surface of the cuticular wax and penetrate into the plant when the concentration of pollutants on the leaf surface exceeds the equilibrium value (Kvesitadze et al. 2006). The adsorption of cuticular wax comprises 46% of the capacity of Dracaena sanderiana to remove benzene (Treesubsuntorn and Thiravetyan 2012), and 20%, 23%, 25%, and 26% of the capacity of Zamioculcas zamiifolia Engl. to remove benzene, toluene, ethylbenzene, and xylene, respectively (Sriprapat and Thiravetyan 2013). Formaldehyde can also enter the plant directly through the opened stomata, which play a significant role in the purification of pollutants in the aerial part. ...
Article
Full-text available
Decorative plants can efficiently purify formaldehyde and improve the quality of indoor air. The existing studies primarily revealed that the aerial and underground parts of plants’ capacity to purify formaldehyde, while the performance of stems is unclear. A formaldehyde fumigation experiment was conducted on Epipremnum aureum and Rohdea japonica in a sealed chamber. Results showed the stems could remove formaldehyde. The efficiency of removal by the stems of each plant was 0.089 and 0.137 mg∙m−3∙h−1, respectively, the rate of purification was 40.0 and 61.6%, respectively. Both were related to plant species and the latter was affected by other factors like exposed area. To further explore the mechanism of phytoremediation, the correlation between the concentration of formaldehyde and CO2 during the experiment was investigated. Results showed when leaves of plants were exposed to formaldehyde, the concentration of CO2 increased with the decrease in concentration of formaldehyde, and the change in concentration of CO2 could be used as an indicator of the degree of decontamination of formaldehyde by the plants.
... Additionally, indoor plants can add life to a sterile office, provide privacy, and abate noise levels(Burton 2001). Compared to conventional air purification techniques, indoor plants offer an environment-friendly cost-effective purification of indoor air by eliminating harmful toxins and particulate matter(Gawronska and Bakera 2015) as proven by systematic evaluation of 28 commonly used ornamental indoor plant species for their ability to remove volatile indoor pollutants: aromatic hydrocarbons (benzene and toluene), aliphatic hydrocarbon (octane), halogenated hydrocarbon, and terpene (α-pinene)(Yang et al. 2009;Treesubsuntorn and Thiravetyan 2012;Cruz et al. 2014;Parseha et al. 2018). ...
... ). Indoor plants consist of a wide variety of native and introduced herbs, shrubs, dwarf trees, climbers, and succulents. The potential role of the indoor plants largely varies with their genetic variation, species, and habit(Park et al. 2010;Aydogan and Montoya 2011;Treesubsuntorn and Thiravetyan 2012; ...
Chapter
Breeders need access to unique genetic variability to meet the growing demand for food while maintaining sustainable agricultural production with the impacts of climate change for generating high-quality nutritional food. Changes in climate and anthropogenic activities and a multitude of environmental influences pose severe threats to food supply and preservation of natural diversity. For example, unpredictable droughts, elevated temperature, and new diseases and pests threaten crop production. Thus, breeding with crop wild relatives (CWR) gives significant resilience to modern agricultural systems and the ability to help sustainably boosting agricultural productivity. As a result, numerous genotype screenings are necessary for broad adaptability, producing a segregating material through fast breeding or rapid generation to shorten the breeding cycle and improving genetic gain. In addition, CWR genomics generates data that support CWR’s usage to boost agricultural genetic diversity. QTL mapping, identifying of candidate genes by next-generation sequencing, gene-based marker development, or significant candidate gene pyramiding of stress-responsive loci in popular cultivar are required to maintain the sustainability of crop production. Thus, genomic data is useful for identifying and isolating novel and dominant alleles of genes from crop gene pools that are agronomically important, which can be used to generate improved crop cultivars. Hence, the natural allelic difference in candidate genes that influences major agronomic characteristics and crop development initiatives is being investigated via allele mining. Among the CWRs of economically important crops, the wild species of rice is essential to improve modern rice cultivars. The awareness of novel genetic and genomic approaches of rice genetic resources for efficient utilization is crucial. Further, their conservation status and availability have not been quantified globally. As a result, a joint effort is required to improve the conservation and accessibility of crop wild relatives for rice breeding. Keywords: Genomics of CWR, Crop improvement, Rice genetic resources
... Research on benefits of indoor plants spans noise reduction, air conditioning, contribution to positive outcomes on health and comfort of occupants and air pollution abatement [1]. For indoor removal of air pollution, many foliage plants have been shown to reduce particulate matter [2], carbon dioxide [3,4], carbon monoxide, nitrogen dioxide [5], ozone [6] and volatile organic compounds (VOCs) [7][8][9][10][11]. Petit et al.'s review covers recent work in all these areas [12]. ...
... Removal of VOCs by potted plants is known to occur through both biodegradation by microbes residing in potted soils and on plant leaves and through diffusion and metabolism by plants themselves [9,13]. Examples of indoor foliage plants that have been experimentally shown to effectively remove VOCs are: English ivy (Hedera helix) and lucky bamboo (Dracaena sanderiana) for benzene removal, snake plant (Sansevieria trifasciata) for toluene removal, spider plant (Chlorophytum comosum) for ethylbenzene removal [7,10,11]. An extensive list of VOCs and plants that remove them has been collated by Petit et al. [12]. ...
... As a possible solution to mitigate poor indoor air quality, a large body of research has tested the capacity of potted plants to clean VOCs from the indoor environment (Aydogan and Montoya 2011; Cruz et al. 2014a, b;Hörmann et al. 2017Hörmann et al. , 2018Irga et al. 2013;Orwell et al. 2004;Sriprapat et al. 2014;Sriprapat and Thiravetyan 2013;Teiri et al. 2018;Treesubsuntorn et al. 2013;Treesubsuntorn and Thiravetyan 2012;Wood et al. 2002). The use of plants for indoor air remediation offers an economical and sustainable departure from conventional techniques, such as adsorption filters, photocatalytic oxidation purifiers and ozone generators, that are often expensive, remove a constrained range of VOCs, and can produce harmful by-products ). ...
... The current study represents the first work conducted to compare the in situ VOC and PM removal capabilities of the major phytoremediation technologies to add further evidence to support the use of these systems as plausible solutions for managing indoor air quality. Several previous studies have assessed the capacity of potted plants (or parts of potted plants) to adsorb and degrade VOCs (Aydogan and Montoya 2011; Hörmann et al. 2018;Irga et al. 2013;Kim et al. 2016;Sriprapat et al. 2014;Thiravetyan 2013, 2016;Treesubsuntorn et al. 2013;Treesubsuntorn and Thiravetyan 2012), whilst a lesser number of studies have measured the effects that potted plants have had on ambient concentrations of VOCs in realistically sized rooms (Wood et al. 2006), and only a very limited number of studies have demonstrated VOC removal by active or passive green walls in situ (Darlington et al. 2001). The current work has shown that in a small airtight room with elevated VOC concentrations, a reasonable density of potted plants or a reasonably sized passive green wall does not provide substantial reductions in the concentrations of VOCs within a relatively short time period (i.e.~37 min in this experiment). ...
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Atmospheric pollutant phytoremediation technologies, such as potted plants and green walls, have been thoroughly tested in lab-scale experiments for their potential to remove air pollutants. The functional value of these technologies, however, is yet to be adequately assessed in situ, in ‘high value’ environments, where pollutant removal will provide the greatest occupant health benefits. Air pollution in countries such as China is a significant public health issue, and efficient air pollution control technologies are needed. This work used pilot-scale trials to test the capacity of potted plants, a passive green wall and an active green wall (AGW) to remove particulate matter (PM) and total volatile organic compounds (TVOCs) from a room in a suburban residential house in Sydney, Australia, followed by an assessment of the AGW’s potential to remove these pollutants from a classroom in Beijing. In the residential room, compared to potted plants and the passive green wall, the AGW maintained TVOCs at significantly lower concentrations throughout the experimental period (average TVOC concentration 72.5% lower than the control), with a similar trend observed for PM. In the classroom, the AGW reduced the average TVOC concentration by ~ 28% over a 20-min testing period compared to levels with no green wall and a filtered HVAC system in operation. The average ambient PM concentration in the classroom with the HVAC system operating was 101.18 μg/m³, which was reduced by 42.6% by the AGW. With further empirical validation, AGWs may be implemented to efficiently clean indoor air through functional reductions in PM and TVOC concentrations.
... The duration of the experiment is an important factor. In published studies, the exposure time in chamber experiments varied between 2 h (Liu et al. 2007) and several days (Treesubsuntorn and Thiravetyan 2012). It is described that plants may need some time for the induction of VOC removal (at least 24 h) Wood et al. 2002) and that the VOC removal may vary diurnally (Liu et al. 2007). ...
... Investigations by Xu et al. (2011) revealed a higher uptake of formaldehyde during daytime versus nighttime for aerial plant parts of Chlorophytum comosum, Aloe vera, and Epipremnum aureum as well. In entireplant experiments (entire plant = aerial parts and growing media including microorganisms and roots), a higher VOC uptake under light conditions was also described by Treesubsuntorn & Thiravetyan (2012) for the removal of benzene by Dracaena sanderiana. In contrast, investigations on the removal efficiency of entire plants of different species (Hedera helix, Chrysanthemum morifolium, Dieffenbachia compacta, and E. aureum) by Aydogan & Montoya (2011) showed that the uptake of formaldehyde is higher under dark, rather than at light conditions. ...
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A unique test chamber system, which enables experiments with plants under highly controlled environmental conditions, was used to examine the pollutant removal efficiency of plants. For this purpose, the removal of two different volatile organic compounds (VOC) (toluene, 2-ethylhexanol) from the air by aerial plant parts of two common indoor plant species (Dieffenbachia maculata and Spathiphyllum wallisii) was monitored. While the control over environmental conditions (temperature, relative humidity, CO2 content, and light condition) worked very well in all experiments, control experiments with the empty chamber revealed high losses of VOC, especially 2-ethylhexanol, over the test duration of 48 h. Nonetheless, compared to the empty chamber, a significantly stronger and more rapid decline in the toluene as well as in the 2-ethylhexanol concentrations was observed when plants were present in the chamber. Interestingly, almost the same VOC removal as by aerial plant parts could be achieved by potting soil without plants. A comparative literature survey revealed substantial heterogeneity in previous results concerning the VOC removal efficiency of plants. This can be mainly attributed to a high diversity in experimental setup. The experimental setup used in the current study offers an excellent opportunity to examine also plant physiological responses to pollutant exposure (or other stressors) under highly controlled conditions. For the analysis of VOC removal under typical indoor conditions, to obtain data for the assessment of realistic VOC removal efficiencies by plants in rooms and offices, a guideline would be helpful to achieve more coherent findings in this field of research.
... In contrast to the EtOAc removal trials, the most effective plant species for benzene removal was N. glabra, likely due to the high wax content in its leaf cuticles, although stomatal benzene uptake has also been proposed in previous work (Setsungnern et al. 2017). Alternatively, S. arboricola has been shown to have high benzene removal efficiency, which has been previously attributed to its relatively large leaf area (Parseh et al. 2018), along with a significant waxy cuticle comprised of alpha-linoleic acid and dodecyl cyclohexane (Treesubsuntorn and Thiravetyan 2012). Interestingly, in this study, no significant associations were found between benzene SPRE and any leaf traits, and thus we cannot determine the pathway for benzene removal observed for N. glabra in the current work, nor can we eliminate effects that this species may have had on the substrate as the means by which enhanced benzene removal was afforded. ...
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Volatile organic compounds (VOCs) are of public concern due to their adverse health effects. Botanical air filtration is a promising technology for reducing indoor air contaminants, but the underlying mechanisms are not fully understood. This study assessed active botanical biofilters for their single-pass removal efficiency (SPRE) for benzene, ethyl acetate and ambient total volatile organic compounds (TVOCs), at concentrations of in situ relevance. Biofilters containing four plant species (Chlorophytum orchidastrum, Nematanthus glabra, Nephrolepis cordifolia ‘duffii’ and Schefflera arboricola) were compared to discern whether plant selection influenced VOC SPRE. Amongst all tested plant species, benzene SPREs were between 45.54 and 59.50%, with N. glabra the most efficient. The botanical biofilters removed 32.36–91.19% of ethyl acetate, with C. orchidastrum and S. arboricola recording significantly higher ethyl acetate SPREs than N. glabra and N. cordifolia. These findings thus indicate that plant type influences botanical biofilter VOC removal. It is proposed that ethyl acetate SPREs were dependent on hydrophilic adsorbent sites, with increasing root surface area, root diameter and root mass all associated with increasing ethyl acetate SPRE. The high benzene SPRE of N. glabra is likely due to the high wax content in its leaf cuticles. The SPREs for the relatively low levels of ambient TVOCs were consistent amongst plant species, providing no evidence to suggest that in situ TVOC removal is influenced by plant choice. Nonetheless, as inter-species differences do exist for some VOCs, botanical biofilters using a mixture of plants is proposed.
... The entry of the pollutants in the leaf tissue occurs either via the open stomata on the leaf epidermis or by diffusion through the epidermis that is covered by a waxy cuticle 16 . Entry through stomata has been assessed by several studies addressing the impact of stomatal density on VOC removal efficiency of various plant species 17,18 . The alternative route of entry is through the cuticle, which is permeable to both lipophilic and hydrophilic molecules. ...
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Plant based biofilters associated with microorganisms have been gaining popularity in controlling odorous compounds like volatile organic compounds (VOCs) as they are cost effective and an environment friendly alternative to conventional air pollution control techniques. In this context, here, we tried to evaluate the performance of potted plants based Claire's biofilter for biodegradation of benzene. A sealed perspex chamber with lid and fan was designed to ensure minimum leakage, proper aeration and distribution of benzene inside the chamber. Five different ornamental indoor plants were placed inside the chamber sequentially and exposed to a concentration of 5 ppm benzene for 30 h each. The leakage of benzene was checked beforehand. Epipremnum aureum (Money plant) showed maximum benzene degradation in the aforementioned time period with a removal efficiency of 98%. The µ max and K s values for 100 ppm concentration of benzene were calculated to be 0.284 h-1 and 0.427 g/m 3 , respectively.
... Therefore, the choice of plant species can also be an important factor for botanical biofilters . Previous studies reported that Sansevieria trifasciata and Chlorophytum comosum could remove indoor air pollution, such as formaldehyde, acetone, benzene, and xylene, from the air (Kim et al. 2010;Lee and Hyunkyung 2015;Khaksar et al. 2016;Setsungnern et al. 2017;Treesubsuntorn and Thiravetyan 2012;Sriprapat and Thiravetyan 2016). In addition, it has been reported that C. comosum could accumulate PM in all size fractions (Gawrońska and Bakera 2015). ...
Article
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Botanical biofilters have been proposed as an effective technology for indoor air remediation. Plants, including Sansevieria trifasciata and Chlorophytum comosum, which remove VOCs effectively, can also reduce CO2 emission since S. trifasciata and C. comosum are CAM and C3 plant species, respectively. Therefore, a botanical biofilter using these plants together shows potential for use in contaminated sites. Herein, the potential of this mixed plant botanical biofilter was evaluated as a method of phytoremediation for multi-pollutants from cigarette smoke. The results showed that the combination of S. trifasciata and C. comosum in a botanical biofilter was highly effective in removing VOCs and PM2.5. In addition, this botanical biofilter can also successfully remove formaldehyde, acetone, benzene, and xylene, with low CO2 emission under indoor conditions of moderate light intensity (50 μmole PAR m⁻² s⁻¹). The system was also installed in a large volume room (24 m³) to test phytoremediation of multi-pollutants from cigarette smoke. The results showed that this mixed plant botanical biofilter can remediate indoor air pollution effectively under both light and dark conditions continuously for three cycles. The mixed plant botanical biofilter developed showed potential for use in real contamination sites.
... When seedlings are able to achieve this process, the technique is called blastofiltration [50]. -Phytodegradation is the degradation of pollutants by plant-microbe systems in which enzymatic activities can facilitate organics biodegradation [24]; and -Phytoscrubbing is the plant removal of atmospheric pollutants [51], as in the case of organics such as benzene that can be efficiently removed from air by Dracena sanderiana plants [52]. Another recent example of phytoscrubbing is given by plants from the Ericaceae family which was screened to remove gaseous pollutants [53]. ...
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Environmental contamination has become a concerning issue worldwide due to number of risks it poses to human health and ecosystem functioning. Contaminants present in soils or waters can go up through the trophic chain via microbial or plant incorporation. Bio/Phytoremediation is an emerging technology for large-scale removal or detoxification of contaminants from the environment. It makes the use of plants and associated microbial communities to remove, transfer, or stabilize pollutants in an environmental friendly manner. This chapter discusses the biotechnological research including genetic engineering, hairy root culture, and identification of the genes or physiological processes in optimizing efficacy of plants as phytoremediators. Hairy root cultures constitute an important tool in phytoremediation research and may provide an ideal model system to identify the role of plants in phytoremediation. Future studies on hairy roots system in relation to phytoremediation should focus on the engineering of target genes involved in this process and to extend the basic hairy root phytoremediation model to the environment.
... It was therefore concluded that these compounds were taken up through the stomata, as stomata open in light and close in darkness. 28,67,74,75 The pathway for VOC uptake by the above-ground plant parts seems likely to dependent on the properties of VOCs. A hydrophilic VOC such as formaldehyde has been found to diffuse easily through the cuticle that consists of lipids, whereas a lipophilic VOC such as benzene was found to more likely penetrate through the cuticle. ...
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This paper reviews the state of art of vegetation systems and their effect on the indoor environmental quality (IEQ), based on scientific studies from the past 30 years. Some studies have shown that biophilic workspaces and interaction with plants may change human attitudes, behaviours, improve productivity and the overall well-being. Evapotranspiration from plants helps lowering the temperature around the planting environment and this can be utilised for air cooling and humidity control. Also, indoor greenery can be used to reduce sound levels as a passive acoustic insulation system. Living wall systems in combination with biofiltration are emerging technologies to provide beneficial effects on improvement of indoor comfort. Several studies have indicated that green systems may improve indoor air quality and that they have different pathways for pollutant removal of volatile organic compounds. The plant root zone in potted plants may be an effective area for removing volatile organic compounds under controlled conditions. In conclusion, the full capacity of plants in real-life settings will need to be clarified to establish the true pollutant-removal mechanisms and the general effect on IEQ. The effects of green systems in combination with mechanical elements such as conventional heating, ventilation and air conditioning would need to be studied.
... Meanwhile, phytoremediation has the advantages of requiring no energy consumption, causing no secondary pollution, and easy application in large or small areas and at different light intensities [21,22]. Phytoremediation is more suitable for the development of cheaper pollution control technologies for outdoor air than phytochemical oxidation because it is more easily controlled by humans. ...
Article
Indoor potted plants played an important role in the removal of air-borne VOCs. According to the difference between plant fresh extracts and boiled extracts on breakdown ability to the added formaldehyde, a simple quantitative evaluation method was used to identify the mechanisms of formaldehyde removal from the air by wild Taraxacum mongolicum Hand.-Mazz. and Plantago asiatica L.. After shoots exposure to formaldehyde (1.28 mg/m3 in the air) for 24 h, the formaldehyde removal rates of P. asiatica and T. mongolicum were 73.18 and 121.20 mg/h/kg FW (fresh weight), respectively. Formaldehyde can be transported from the air to the rhizosphere solution by plants, and the maximum rates of transmission by T. mongolicum and P. asiatica were 23.73 and 83.08 mg/h/kg FW, respectively. Although plant metabolism was responsible for formaldehyde loss in the air-plant-solution system, and the metabolic activity depended on the enzymatic and redox reactions in the plants, P. asiatica and T. mongolicum are still good candidate species for developing phyto-microbial technologies. The redox reaction was the main mechanism used by P. asiatica shoots to dissipate formaldehyde, while the enzymatic reaction was the main mechanism used by T. mongolicum. The higher oxidative potential and lower defensive enzyme activity in P. asiatica shoots led to its higher formaldehyde removal rate compared to T. mongolicum. Meanwhile, the stronger redox reaction ability in the T. mongolicum roots was partly responsible for its lower formaldehyde transmission rate. The results show two plants have strong tolerance to formaldehyde in the air and good formaldehyde removal ability.
... It was assumed that enzymes were performing the first step in the oxidative transformation of benzene in plant leaves containing copper as the prosthetic group (Ugrekhelidze et al. 1997). Stomata and the wax cuticles of plants are also important areas for benzene uptake (Treesubsuntorn and Thiravetyan 2012). Therefore, it was the day stomata opening and night closing involving the pollution removal. ...
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Humans have a close relationship with nature, and so integrating the nature world into indoor space could effectively increase people’s engagement with nature, and this in turn may benefit their health and comfort. Since people spend 80–90% of their time indoors, the indoor environment is very important for their health. Indoor plants are part of natural indoor environment, but their effect on the indoor environment and on humans has not been quantified. This review provides a comprehensive summary of the role and importance of indoor plants in human health and comfort according to the following four criteria: photosynthesis; transpiration; psychological effects; and purification. Photosynthesis and transpiration are important mechanisms for plants, and the basic functions maintaining the carbon and oxygen cycles in nature. Above all have potential inspiration to human’s activities that people often ignored, for example, the application of solar panel, artificial photosynthesis, and green roof/facades were motivated by those functions. Indoor plants have also been shown to have indirect unconscious psychological effect on task performance, health, and levels of stress. Indoor plants can act as indoor air purifiers, they are an effective way to reduce pollutants indoor to reduce human exposure, and have been widely studied in this regard. Indoor plants have potential applications in other fields, including sensing, solar energy, acoustic, and people’s health and comfort. Making full use of various effects in plants benefit human health and comfort.
... [38,39] It was, therefore, concluded that formaldehyde was taken up through the stomata as stomata are open in light and closed in darkness. [40,41] Another explanation can be the increase in the photosynthesis and metabolism rate in daytime leads to more formaldehyde removal compared to night time. [42,43] It has been reported in some studies that the removal rate in the first ours is higher and decreases by the passage of time. ...
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Background Formaldehyde is a common hazardous indoor air pollutant which recently raised public concerns due to its well-known carcinogenic effects on human. The aim of this study was to investigate a potted plant-soil system ability in formaldehyde removal from a poor ventilated indoor air to promote dwellers health. Methods For this purpose, we used one of the common interior plants from the fern species (Nephrolepis obliterata), inside a Plexiglas chamber under controlled environment. Entire plant removal efficiency and potted soil/roots contribution were determined by continuously introducing different formaldehyde vapor concentrations to the chamber (0.6–11 mg/m³) each over a 48-h period. Sampling was conducted from inlet and outlet of the chamber every morning and evening over the study period, and the average of each stage was reported. Results The results showed that the N. obliterata plant efficiently removed formaldehyde from the polluted air by 90%–100%, depending on the inlet concentrations, in a long time exposure. The contribution of the soil and roots for formaldehyde elimination was 26%. Evaluation of the plant growing characteristics showed that the fumigation did not affect the chlorophyll content, carotenoid, and average height of the plant; however, a decrease in the plant water content was observed. Conclusions According to the results of this study, phytoremediation of volatile organic compound-contaminated indoor air by the ornamental potted plants is an effective method which can be economically applicable in buildings. The fern species tested here had high potential to improve interior environments where formaldehyde emission is a health concern.
... Not only plant species but also light is the factor affecting VOC removal rate (Dela Cruz et al., 2014). Many researches exhibited that plants under 24 h white fluorescent light conditions could harbor higher gaseous benzene removal efficiency than under dark conditions due to the stomata are closed in the absence of light and opened in the presence of light ( Wood et al., 2001;Treesubsuntorn and Thiravetyan, 2012). Therefore, light affected to benzene removal efficiency. ...
Article
Benzene, a carcinogenic compound, has been reported as a major indoor air pollutant. Chlorophytum comosum (C. comosum) was reported to be the highest efficient benzene removal plant among other screened plants. Our previous studies found that plants under light conditions could remove gaseous benzene higher than under dark conditions. Therefore, C. comosum exposure to airborne benzene was studied under different light quality at the same light intensity. C. comosum could remove 500 ppm gaseous benzene with the highest efficiency of 68.77% under Blue:Red = 1:1 LED treatments and the lowest one appeared 57.41% under white fluorescent treatment within 8 days. After benzene was uptaken by C. comosum, benzene was oxidized to be phenol in the plant cells by cytochrome P450 monooxygenase system. Then, phenol was catalyzed to be catechol that was confirmed by the up-regulation of phenol 2-monooxygenase (PMO) gene expression. After that, catechol was changed to cic, cis-muconic acid. Interestingly, cis,cis-muconic acid production was found in the plant tissues higher than phenol and catechol. The result confirmed that NADPH-cytochrome P450 reductase (CPR), cytochrome b5 (cyt b5), phenol 2-monooxygenase (PMO) and cytochrome P450 90B1 (CYP90B1) in plant cells were involved in benzene degradation or detoxification. In addition, phenol, catechol, and cis,cis-muconic acid production were found under the Blue-Red LED light conditions higher than under white fluorescent light conditions due to under LED light conditions gave higher NADPH contents. Hence, C. comosum under the Blue-Red LED light conditions had a high potential to remove benzene in a contaminated site.
... Inoculated plants demonstrated increased tolerance to VOC stress, along with greatly increased removal rates for several VOCs. Treesubsuntorn and Thiravetyan (2012) identified the microbial consortium associated with TMA removal from plant rhizospheres, and used them to bioaugment the rhizospheres of plants, which subsequently demonstrated greater TMA removal. Zhang et al. (2013) isolated rhizospheric bacteria that possess the gene for toluene monooxygenase, offering a potential candidate culture for future rhizosphere augmentation trials. ...
... Several potted plant studies have noted the capacity of aerial plant parts to remove VOCs from the ambient air (Dela Cruz et al., 2014), which may occur through stomatal uptake (Treesubsuntorn and Thiravetyan, 2012), adsorption to the leaf cuticle (Treesubsuntorn et al., 2013), or breakdown by VOC-degrading microorganisms within the phyllosphere (Sriprapat and Thiravetyan, 2016). The removal rates in these passive system experiments, however, are invariably limited by the rate of pollutant diffusion from source to sink, and it is unknown how these removal mechanisms perform in active botanical biofilters. ...
... In addition to stomatal VOC uptake, VOCs can also be adsorbed on the leaf cuticle by dry or wet deposition (Treesubsuntorn and Thiravetyan, 2012). Adsorbed VOCs can diffuse into leaf cells through aqueous pores within the cuticle (Seco et al., 2007). ...
... The difference in metabolic activity between compounds is also a key factor; however, it is unclear, with limited evidence in the present study, whether metabolic activity converting benzaldehyde is lower than those converting phenol and benzyl alcohol. Accumulation of MAHs into leaf cuticular wax might occur (Treesubsuntorn and Thiravetyan, 2012). However, in the present study the regression line between stomatal conductance and normalized uptake rate passed through the origin (Fig. 4), indicating that the deposition causing the accumulation into leaf cuticular wax was negligible low when stomata was closed. ...
Article
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Large amounts of monocyclic aromatic hydrocarbons (MAHs) are emitted into the atmosphere, but it is unclear which compounds among MAHs are effectively removed by the above-ground parts of plants. Although fumigation experiments of MAHs at unrealistically high concentrations (~ppmv) have been conducted, experiments with ambient concentrations have scarcely been conducted. In the present study, MAHs, including benzene, toluene, phenol, benzaldehyde, and benzyl alcohol, with concentrations ranging from several to several tens ppbv, were individually fumigated to four plant species, and the uptake was monitored using proton-transfer-reaction mass spectrometry and gas chromatography-mass spectrometry. No detectable uptake was observed for benzene and toluene, but phenol, benzaldehyde, and benzyl alcohol were significantly taken up by the plants. The uptake rate normalized to fumigated concentration varied from 3 to 50 mmol m⁻²s⁻¹ during the light period, depending on light intensity and compounds. The difference in uptake capability may be attributed not only to different metabolic activities but also to different values of Henry’s law constant, which regulates the partitioning of these compounds into the liquid phase in leaves. The uptake of phenol, benzaldehyde, and benzyl alcohol was affected by stomatal conductance, suggesting that stomatal opening is the main factor regulating the uptake of the three MAHs. This is the first observation that anisole is emitted when phenol is fumigated to Spathiphyllum clevelandii, suggesting that phenol is methylated to anisole within plant leaves. Anisole is more volatile than phenol, meaning that methylation enhances the emission of xenobiotics into the atmosphere by converting them to more volatile compounds. This conversion ratio decreased with an increase in phenol concentration (from 1.3 to 143 ppbv). Considering low reaction rate coefficient of anisole with OH radicals and low conversion ratio from phenol to anisole, it is concluded that plants act to effectively remove oxygenated MAHs from the atmosphere.
... Moreover, banana leaves have more stomata when compared to branches and peels. Stomata are an important pathway for air pollutant uptake in plants [34]. Thus, having more stomata means having greater potential to absorb gaseous pollutants. ...
Article
Bananas have the highest production rate among fruits in Indonesia, which leads to the generation of a significant amount of banana fruit solid waste. In this study, we assessed the potential use of banana waste to remove hydrogen sulfide (H2S) gas. In particular, the purpose of this study was to analyze the efficiency of banana waste as an adsorbent for H2S gas. We tested the stems, leaves, and peels of banana plants as H2S gas adsorbents with varying contact times. To obtain a microscopic view of the adsorbents before and after the experiment, we conducted measurements using scanning electron microscopy with dispersive X-ray spectroscopy. The banana leaves, stems, and peels were found to have H2S gas absorption efficiency values of 76.52%, 51.83%, and 6.44%, respectively. Based on the experiment, the leaves of the banana plant appear to be the best adsorbents, with an adsorption capacity of 1.67 mg/g. The results also revealed that there was a change in the fiber and stomata appearance of the banana leaves after the adsorption process. Overall, this research indicates that banana leaves have the potential to be used as effective H2S adsorbents.
... The ornamental plants have the ability to absorb, distribute, and/or transport organic pollutants through mechanisms such as rhizosphere biodegradation (by microorganisms), phytoextraction (plant-liquid extraction), stomatal uptake (plant-gas extraction), phytodegradation (via enzymatic catalysis inside tissues), and phytovolatilization (directly by evaporation from leaves or indirectly by plant transpiration) (Soreanu et al. 2013). The bioremediation capability of different pollution abatement plants such as Dieffenbachia compacta (Formaldehyde) (Aydogan and Montoya 2011), Sansevieria trifasciata (Benzene) (Treesubsuntorn and Thiravetyan 2012), Chlorophytum comosum, Dracaena deremensis, Philodendron domesticum (Benzene, formaldehyde, trichloroethylene) (Wolverton et al. 1989), and Schefflera actinophylla (Toluene, Xylene) (Kim et al. 2016) has been well reported. This recognition has contributed to a rise in the selling of indoor plants. ...
Article
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Deterioration of indoor air quality (IAQ) has become a serious concern as people spend lots of time indoors and prolonged pollution exposure can result in adverse health outcomes. Indoor plants can phytoremediate a wide variety of indoor contaminants. Nonetheless, few experiments have demonstrated their efficacy in real-time environments. Therefore, the present study aims to experimentally assess the efficiency of Areca palm potted plants in phytoremediation of primary indoor air pollutant viz. total volatile organic compounds (TVOCs), carbon dioxide (CO2), and carbon monoxide (CO) levels from real-world indoor spaces, for the first time. Four discrete naturally ventilated experimental sites (I-IV) situated at the Council of Scientific and Industrial Research- Institute of Himalayan Bioresource Technology (CSIR-IHBT) were used. For over a period of 4 months, the sites were monitored using zero plants as a control (1–4 week), three plants (5–8 week), six plants (9–12 week), and nine plants (13–16 week), respectively. Present results indicate that Areca palm potted plants can effectively reduce the TVOCs, CO2, and CO levels by 88.16% in site IV, 52.33% and 95.70% in site III, respectively. The current study concluded that Areca palm potted plants offer an efficient, cost-effective, self-regulating, sustainable solution for improving indoor air quality and thereby human well-being and productivity in closed and confined spaces.
... By considering the potential of plants to remove VOCs, there are some studies on benzene removal. Studies showed that plants have high resistance against toxic pollutants [144][145][146]. Recently, Sriprapat et al. [8] exhibited the experimental data for eight species of plant, including Sansevieria trifasciata, Euphorbia milii, Epipremnum aureum, Syngonium podophyllum, Hedera helix, Chlorophytum comosum, Dracaena sanderiana, and Clitoria ternatea, for removing benzene in air and water pollutants. ...
Article
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Urban civilization has a high impact on the environment and human health. The pollution level of indoor air can be 2–5 times higher than the outdoor air pollution, and sometimes it reaches up to 100 times or more in natural/mechanical ventilated buildings. Even though people spend about 90% of their time indoors, the importance of indoor air quality is less noticed. Indoor air pollution can be treated with techniques such as chemical purification, ventilation, isolation, and removing pollutions by plants (phytoremediation). Among these techniques, phytoremediation is not given proper attention and, therefore, is the focus of our review paper. Phytoremediation is an affordable and more environmentally friendly means to purify polluted indoor air. Furthermore, studies show that indoor plants can be used to regulate building temperature, decrease noise levels, and alleviate social stress. Sources of indoor air pollutants and their impact on human health are briefly discussed in this paper. The available literature on phytoremediation, including experimental works for removing volatile organic compound (VOC) and particulate matter from the indoor air and associated challenges and opportunities, are reviewed. Phytoremediation of indoor air depends on the physical properties of plants such as interfacial areas, the moisture content, and the type (hydrophobicity) as well as pollutant characteristics such as the size of particulate matter (PM). A comprehensive summary of plant species that can remove pollutants such as VOCs and PM is provided here. This review will help in making informed decisions about integrating plants into the interior building design.
... Benzene is the most prominent volatile organic compound (VOC) known for its harmful impacts on human health. Based on ACGIH, EPA, and IARC classification, it is considered a carcinogen [1,2]. Long-term exposure to benzene may cause anemia, plastic anemia, and leukemia [3]. ...
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Activated carbon (AC) was prepared from Diplotaxis acris biomass. The change in the surface functional groups between the biomass raw material and the produced AC was detected using Fourier-transform infrared (FTIR) and Raman spectroscopy. The thermal stability of the prepared AC was determined by using thermogravimetric analysis (TGA). It has a surface area of 40.21 m2/g which gave evidence for its external porous surface. The surface porosity and the graphite properties of the prepared AC were detected by scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis, respectively. The amount of adsorbed benzene on the AC surface was determined using a gas chromatograph supported with a flame ionization detector (GC-FID) after extraction in methanol. The adsorption capacity of benzene was 5.4 mg/g at room temperature (25°C), and its removal efficiency reached 95.58% for low benzene concentration (1000 mg/m3). The obtained results were well fitted by the Langmuir isotherm model. The adsorption kinetics of benzene followed the pseudo-second-order kinetic model accompanied by the intra-particle diffusion model. The reuse of the AC samples for three consecutive cycles retained the removal efficiency by more than 75% of its original efficiency. Overall, the study revealed that the prepared AC from Diplotaxis acris biomass has a great potential in the removal of benzene from polluted air.
... However, excessive storage due to the accumulation of deadly concentrations will result in damage to the plant. Eventually, some contaminants can move to the root and remove through the root and can be decomposed by microorganisms in the soil or absorb into the soil (Orwell et al. 2004(Orwell et al. , 2006Wood et al. 2006;Treesubsuntorn and Thiravetyan 2012). In other words, plants can oppose toxic compounds through removal, combination with molecules or decomposition of them into cellular metabolites, and carbon dioxide in some cases, in which the latter is the best way for phytoremediation purposes (Thomas et al. 2015). ...
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In recent decades, indoor air pollution has become a major concern due to its adverse health effects on the inhabitants. The presence of fine particles (PM2.5) and hazardous volatile organic compounds (VOCs), such as formaldehyde and benzene, in indoor air and their proven carcinogenic effects, has raised the attention of health authorities. Their very difficult and expensive removal by chemical and mechanical methods has led researchers to seek an economical and environmentally friendly technique. The use of plants in different ways such as potted plants or green walls is considered as a potential green solution for the improvement of indoor air quality and the health level of its inhabitants. A review of the literature cited in this paper suggests that plants absorb some of the pollutants, such as particles directly and remove some pollutants such as VOCs indirectly through biological transfer or by using microorganisms. This review paper discusses the types of plants that have been used for the phytoremediation of airborne pollutants and the routes and mechanisms for removing the pollutants. Removal pathways of the pollutants by aerial parts of the plants, the growth media along with the roots and their microorganisms in the rhizosphere part were also discussed. Sensitive analysis of extracted data from the literature outlined the most useful types of plants and the appropriate substrate for phytoremediation. Also, it showed that factors affecting the removal efficiency such as light intensity and ambient temperature, behave differently depending on pollutants and plants types.
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Application of biochar to the soil has been reported as one of the mitigation technologies of CH 4 emission from rice cultivation due to its unique characteristics of high porosity and surface area. The application of small particle size of biochar is rich in surface area that may enhance the mitigation potential. Rice cultivation and soil incubation experiments were conducted to evaluate the effect of two groups of biochar particle size on CH 4 emission and production in order to show the mitigation potential. This experiment consists of three treatments including no biochar (CT), small particle size (0.5-2 mm) biochar (SB), and large particle size (2-4 mm) biochar (LB). Both biochar sizes were amended at 10 t ha ⁻¹ equivalent rate and all treatments were applied chemical fertilizer at 100 kg N ha ⁻¹ equivalent rate. The results demonstrated that SB and LB reduced cumulative CH 4 emission by 24.0% and 17.1% and cumulative CH 4 production by 24.6% and 15.0% as compared to CT, respectively. Our results showed that SB achieved higher mitigation potential than LB by an average of 8.47%, although it was not significant. The mitigation of both biochar sizes was supported by the significant change of soil methanogens and methanotrophs abundances. The suppression of methanogens abundance and the stimulation of methanotrophs abundance indicated in the ratio of mcr A to pmo A was significantly reduced in SB (68.0%) which higher than in LB (56.3%) as compared to CT. Both application sizes also increased soil oxidation capacity through soil Eh increase which no difference between SB and LB. In term of grain yield, SB and LB were not different and both did not show the significant change as relative to CT. The application of small size biochar in this study affected more mitigation potential of CH 4 emission as compared to larger size, therefore there is a need of further study on typical size of biochar in order to recommend the most mitigation potential of biochar application.
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Indoor air quality is of emerging importance due to the rapid growth of urban populations that spend the majority of their time indoors. Amongst the public, there is a common perception that potted-plants can clean the air of pollutants. Many laboratory-based studies have demonstrated air pollution phytoremediation with potted-plants. It has, however, been difficult to extrapolate these removal efficiencies to the built environment and, contrary to popular belief, it is likely that potted-plants could make a negligible contribution to built environment air quality. To overcome this problem, active green walls have been developed which use plants aligned vertically and the addition of active airflow to process a greater volume of air. Although a variety of designs have been devised, this technology is generally capable of cleaning a variety of air pollutants to the extent where comparisons against conventional air filtration technology can be made. The current work discusses the history and evolution of air phytoremediation systems from potted-plants through to practical botanical air filtration.
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Benzene, a hydrophobic xenobiotic, induces cell damage in both humans and plants. Due to its volatilization, benzene is an airborne environmental problem. The potential of an exogenous bioactive brassinosteroid phytohormone to enhance benzene removal for phytoremediation was investigated. Chlorophytum comosum had higher brassinosteroids content under benzene stress. Plant treated with 24-epibrassinolide (EBR) removed significantly more gaseous benzene than untreated plants under both light and dark conditions at an initial benzene of 12.75 μmol in the systematic chambers (P < 0.05). Although benzene increased malondialdehyde in plant tissue, EBR-treated plants lowered this lipid peroxidation by enhancing their antioxidant content and increasing benzene detoxification-related genes expression, including ascorbic acid (AsA), homogentisate phytyltransferase (HPT), and glutathione synthethase (GS). This contributed to maintaining higher photosynthetic performances. Moreover, EBR-treated plants had higher gene expression of ferredoxin–NADP reductase (FNR) and glucose-6-phosphate 1-dehydrogenase (G6PDH), thus promoting NADPH biosynthesis to cope with benzene under light and dark conditions, respectively. Further, higher glutathione biosynthesis promoted more glutathione conjugate of benzene products including S-phenylcysteine (SPC) in EBR-treated plants. Hence, application of exogenous EBR as foliar spray provided for enhanced benzene detoxification via antioxidant content, benzene detoxification-related genes and benzene conjugation products with glutathione (GSH) and consequently greater gaseous benzene removal.
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There is a global need to use plants to restore the ecological environment. There is no systematic review of phytoremediation mechanisms and the parameters for environmental pollution. Here, we review this situation and describe the purification rate of different plants for different pollutants, as well as methods to improve the purification rate of plants. This is needed to promote the use of plants to restore the ecosystems and the environment. We found that plants mainly use their own metabolism including the interaction with microorganisms to repair their ecological environment. In the process of remediation, the purification factors of plants are affected by many conditions such as light intensity, stomatal conductance, temperature and microbial species. In addition the efficiency of phytoremediation is depending on the plants species-specific metabolism including air absorption and photosynthesis, diversity of soil microorganisms and heavy metal uptake. Although the use of nanomaterials and compost promote the restoration of plants to the environment, a high dose may have negative impacts on the plants. In order to improve the practicability of the phytoremediation on environmental restoration, further research is needed to study the effects of different kinds of catalysts on the efficiency of phytoremediation. Thus, the present review provides a recent update for development and applications of phytoremediation in different environments including air, water, and soil.
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Air phytoremediation technology has been reported as a high potential technology for indoor air pollution treatment. Since 1996, NASA has supported this technology for application in the international space station. However, changes in plant physiology and hormone levels under microgravity (μG) conditions might affect air phytoremediation efficiency, especially changes of auxin hormone transportation in plants. In this study, the application of Chlorophytum comosum, high benzene removal plant species, to remove 100 ppm gaseous benzene under μG condition was studied. The experiment was operated for three days in a random positioning machine generate 6.44 × 10⁻⁴ G within 1 h. The results showed that under μG, benzene removal efficiency by C. comosum was significantly increased, with a remove more than 80% within three days under both 24 h light and dark conditions. In contrast, C. comosum growing under normal gravity (1G) can remove about 75% and 50% benzene under 24 h light and 24 h dark conditions, respectively. Surprisingly, μG conditions seem to maintain open stomata of a plant open under both 24 h light and dark conditions, and this plant will normally have closed stomata in the dark. In this case, shoot auxin hormone in the form of Indole-3-acetic acid was highly increased in the plant growing under μG. This result suggested that under μG, auxin hormone might be accumulated in the shoot part of plant. This auxin accumulation effect of maintaining open plant stomata can enhance benzene phytoremediation efficiency since stomata are the major benzene uptake pathway. Therefore, this study is the first report presenting the possibility of applying air phytoremediation technology under μG conditions.
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Studies of indoor air quality have prompted serious concerns of occupant's health and human well-being, which might not be fully achieved solely by current ventilation strategies. Environmental exposures to indoor contaminants such as volatile organic compounds (VOCs), and Carbon Dioxide emissions (CO2) levels remain problematic issues that might not be fully addressed through increased levels of ventilation rate only. Living media where plants are able to remove indoor contaminants can provide an effective passive strategy that impact occupant's health, well-being, as well as building's ventilation system efficacy. Despite many studies on horticultural biotechnologies for improving indoor air quality in laboratory settings, active botanical biofilters or functional green walls seem to perform differently in actual indoor spaces rather than being assessed in closed experimental chambers. By introducing the idea of incorporating active botanical green wall systems as an air filtration strategy into double skin facades, a dual benefit might be achieved to improve indoor air quality and the building's energy saving potential by improving thermal performance of the building's envelope. This paper aims at evaluating previous results of biofiltration, botanical air filters, and potted plants by comparing their removal efficiencies to their air chamber volumes based on a meta-analysis of published results. Results are presented through specific defined metrics in which independent variables in the form of, plant species, leaf areas, time, air volume, and chamber geometry are computed to present spatial and technical influences of different experimental conditions in reducing indoor air contaminants. The paper concludes that plants show higher removal efficiencies when placed in enclosed spaces with higher ratio of leave areas to chamber volumes which also increases the rate of filtration. Although plants' latent heat might improve the envelope thermal insulation, air volume and stratification are more significant variables at improving the envelope thermal properties. Further studies are needed to test the impact of enclosed botanical biofilters in field studies and under different climatic and building types to determine the suitability and optimization potential of this strategy for the design of high-performance envelopes.
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Phytoremediation is a sustainable remedial approach for removing benzene from environment. Plant associated bacteria could ameliorate the phytotoxic effects of benzene on plant, although the specificity of these interactions is unclear. Here, we used proteomics approach to gain a better understanding of the mechanisms involved in plant-bacteria interactions. Plant associated bacteria was isolated and subsequently inoculated into the sterilized Helianthus annuus, and the uptake rates of benzene by these inoculated plants were evaluated. At the end of the experiment, leaves and roots proteins were analyzed. The results showed inoculated H. annuus with strain EnL3 removed more benzene than other treatments after 96 hr. EnL3 was identified as Enterobacter sp. according to 16S rDNA analysis. Based on the comparison of proteins, 62 proteins were significantly up or down regulated in inoculated leaves, while 35 proteins were significantly up or down regulated in inoculated roots. Furthermore, there were 4 and 3 identified proteins presented only in inoculated H. annuus leaves and roots, respectively. These proteins involved in several functions including transcription and translation, photosynthesis, and stress response. The network among anti-oxidant defense system, protein synthesis, and photosynthetic electron transfer are involved in collaboratively activate the benzene uptake and stress tolerance in plant.
Chapter
Integrating greeneries into the indoor dwelling environment boosts work performance and relieves stress to add to the overall psychological well-being especially in deserted urban settings. In addition to mental soothing, thermal regulation, air purification, aesthetics, public health, and comfort, the addition of plants to indoor settings may also contribute to the conservation of dwindling floral biodiversity. Despite authorities’ pledge for sustainable urban management, the status of indoor gardening has hitherto remained unexplored in the emerging megapolis of Bangladesh—Chattogram—the second largest urban center of the country. In addressing that gap, this study aims to explore the composition, diversity, and management of indoor plants in urban dwellings at Halishahar of Chattogram based on interviews on 48 households selected through multistage random sampling. Data from all selected households were collected by using a semi-structured questionnaire through physically visiting the households. Almost half of the households (48%) living at Halishahar had indoor plants in their dwellings. The study recorded a handsome 120 indoor plant species belonging to 108 genera from 60 families. While the diversity was in no way comparable to the tropical ecosystem of the country, in consideration of the strict set of requirements for plants to be suitable for an indoor setting, the diversity seemed excellent as evident from four diversity indices. Soil mixed with compost, sand, and surki at different ratios is used as potting media. Pests were identified as the major challenge in managing the indoor plants. Application of domestic manure with the potting media was common as a means to maintain the nutrient flow. Bruised tea leaf is the most frequently added nutrient supplement. Apart from the aesthetic values, urban dwellers from Halishahar reported the immense potential of indoor gardening in supplementing daily nutrition and in mitigating the impacts of climate change. The lessons from this study can be used in informed policymaking for the promotion of biodiversity conservation and other benefits from indoor greening among urban dwellers in Bangladesh.
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Twenty-eight ornamental species commonly used for interior plantscapes were screened for their ability to remove five volatile indoor pollutants: aromatic hydrocarbons (benzene and toluene), aliphatic hydrocarbon (octane), halogenated hydrocarbon [trichloroethylene (TCE)], and terpene (-pinene). Individual plants were placed in 10.5-L gas-tight glass jars and exposed to 10 ppm (31.9, 53.7, 37.7, 46.7, and 55.7 mg·m –3) of benzene, TCE, toluene, octane, and -pinene, respectively. Air samples (1.0 mL) within the glass containers were analyzed by gas chromatography–mass spectroscopy 3 and 6 h after exposure to the test pollutants to determine removal efficiency by monitoring the decline in concentration over 6 h within sealed glass containers. To determine removal by the plant, removal by other means (glass, plant pot, media) was subtracted. The removal efficiency, expressed on a leaf area basis for each volatile organic compound (VOC), varied with plant species. Of the 28 species tested, Hemigraphis alternata, Hedera helix, Hoya carnosa, and Asparagus densiflorus had the highest removal efficiencies for all pollutants; Tradescantia pallida displayed superior removal efficiency for four of the five VOCs (i.e., benzene, toluene, TCE, and -pinene). The five species ranged in their removal efficiency from 26.08 to 44.04 µg·m–3·m–2·h–1 of the total VOCs. Fittonia argyroneura effectively removed benzene, toluene, and TCE. Ficus benjamina effectively removed octane and -pinene, whereas Polyscias fruticosa effectively removed octane. The variation in removal efficiency among species indicates that for maximum improvement of indoor air quality, multiple species are needed. The number and type of plants should be tailored to the type of VOCs present and their rates of emanation at each specific indoor location.
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The quality of the indoor environment has become a major health consideration, since urban-dwellers spend 80-90% of their time indoors, where air pollution can be several times higher than outdoors. Indoor potted-plants can remove air-borne contaminants such as volatile organic compounds (VOCs), over 300 of which have been identified in indoor air. In this study a comparison was made of rates of removal of benzene, as model VOC, by seven potted-plant species/varieties. In static test-chambers, high air-borne doses of benzene were removed within 24 h, once the response had been stimulated (induced) by an initial dose. Removal rates per pot ranged from 12-27 ppm d–1 (40 to 88 mg m–3 d–1) (2.5 to 5 times the Australian maximum allowable occupational level). Rates were maintained in light or dark, and rose about linearly with increased dose. Rate comparisons were also made on other plant parameters. Micro-organisms of the potting mix rhizosphere were shown to be the main agents of removal. These studies are the first demonstration of soil microbial VOC degradation from the gaseous phase. With some species the plant also made a measurable contribution to removal rates. The results are consistent with known, mutually supportive plant/soil-micro-organism interactions, and developments in microbially-based biofilter reactors for cleaning VOC-contaminated air. The findings demonstrate the capacity of the potted-plant microcosm to contribute to cleaner indoor air, and lay the foundation for the development of the plant/substrate system as a complementary biofiltration system.
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Indoor air-borne loads of volatile organic compounds (VOCs) are usually significantly higher than those outdoors, and chronic exposures can cause health problems. Our previous laboratory studies have shown that the potted-plant microcosm, induced by an initial dose, can eliminate high air-borne VOC concentrations, the primary removal agents being potting-mix microorganisms, selected and maintained in the plant/root-zone microcosm. Our office field-study, reported in the preceding paper, showed that, when total VOC (TVOC) loads in reference offices (0 plants) rose above about 100 ppb, levels were generally reduced by up to 75% (to < 100 ppb) in offices with any one of three planting regimes. The results indicate the induction of the VOC removal mechanism at TVOC levels above a threshold of about 100 ppb. The aims of this laboratory dose-response study were to explore and analyse this response. Over from 5 to 9 days, doses of 0.2, 1.0, 10 and 100 ppm toluene and m-xylene were applied and replenished, singly and as mixtures, to potted-plants of the same two species used in the office study. The results confirmed the induction of the VOC removal response at the lowest test dosage, i.e in the middle of the TVOC range found in the offices, and showed that, with subsequent dosage increments, further stepwise induction occurred, with rate increases of several orders of magnitude. At each dosage, with induction, VOC concentrations could be reduced to below GC detection limits (< 20 ppb) within 24 h. A synergistic interaction was found with the binary mixtures, toluene accelerating m-xylene removal, at least at lower dosages. The results of these two studies together demonstrate that the potted-plant microcosm can provide an effective, self-regulating, sustainable bioremediation or phytoremediation system for VOC pollution in indoor air.
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Small, volatile hydrocarbons, including trichloroethylene, vinyl chloride, carbon tetrachloride, benzene, and chloroform, are common environmental pollutants that pose serious health effects. We have developed transgenic poplar (Populus tremula × Populus alba) plants with greatly increased rates of metabolism and removal of these pollutants through the overexpression of cytochrome P450 2E1, a key enzyme in the metabolism of a variety of halogenated compounds. The transgenic poplar plants exhibited increased removal rates of these pollutants from hydroponic solution. When the plants were exposed to gaseous trichloroethylene, chloroform, and benzene, they also demonstrated superior removal of the pollutants from the air. In view of their large size and extensive root systems, these transgenic poplars may provide the means to effectively remediate sites contaminated with a variety of pollutants at much faster rates and at lower costs than can be achieved with current conventional techniques. • CYP2E1 • P450 • poplar • trichloroethylene • carbon tetrachloride
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Plant uptake rate constants (k1) were determined for vapor-phase 2,3,7,8-TCDD using grass, azalea, spruce, kale and pepper foliage, and the fruit from apple, tomato and pepper. Plants were exposed to vapor-phase 3H-2,3,7,8-TCDD for 96 h, and the TCDD sorption rate constant for each plant species was determined from measured air and plant concentrations. Sorption rate constants for the different plant tissues, expressed on a fresh weight basis (k1FWt with units of gAir gFWt−1 h−1), varied by two orders of magnitude. The rate constants were normalized for the exposed plant surface area (SA) by dividing k1FWt by the SA/FWt ratio for each plant species. Normalizing the rate constants for exposed surface area resulted in significantly less variation between species (k1SA = 1.2 gAir cm2 −1 h−1 ± 0.2 SE). The cuticular wax content of the different plant species did not effect the short-term sorption kinetics of 2,3,7,8-TCDD.
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The air-to-vegetation pathway may substantially contribute to human and food-chain exposure to organic chemicals since the surface area of the above-ground parts of vegetation by far exceeds the area the plants are growing on. A model for assessing the atmosphere-to-vegetation transfer of persistent organic chemicals is discussed. It is based on the fugacity concept and uses the 1-octanol/water and cuticle/water partition coefficients, aqueous solubility, and the saturation vapor pressure of the chemicals as input data. Equilibrium concentrations in plant tissues and air-to-vegetation bioconcentration factors can be estimated. Further, the model permits prediction of the compartment(s) in vegetation where a given chemical will preferentially accumulate. An approach for assessing semiquantitatively the potential for (re)volatilization of organics from leaves is also suggested. Various applications of the model are shown for reference compounds of widely differing physicochemical properties.
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Photosystem II plays an especially important role in the response of photosynthesis in higher plants to environmental perturbations and stresses. The relationship between photosystem II and photosynthetic CO2 assimilation is examined and factors identified that may modulate photosystem II activity in vivo. Particular attention is given to non-photochemical quenching of excitation energy, photoinhibition, state transitions, protein phosphorylation and biogenesis of photosystem II.
Article
Phytoremediation—using plants to remove toxins—is an attractive and cost effective way to improve indoor air quality. This study screened ornamental plants for their ability to remove volatile organic compounds from air by fumigating 73 plant species with 150 ppb benzene, an important indoor air pollutant that poses a risk to human health. The 10 species found to be most effective at removing benzene from air were fumigated for two more days (8 h per day) to quantify their benzene removal capacity. Crassula portulacea, Hydrangea macrophylla, Cymbidium Golden Elf., Ficus microcarpa var. fuyuensis, Dendranthema morifolium, Citrus medica var. sarcodactylis, Dieffenbachia amoena cv. Tropic Snow; Spathiphyllum Supreme; Nephrolepis exaltata cv. Bostoniensis; Dracaena deremensis cv. Variegata emerged as the species with the greatest capacity to remove benzene from indoor air.
Article
Pine needles were used as passive samplers for monitoring polychlorinated biphenyls (PCBs) in the environment. A method for the determination of PCB in pine needle wax was developed. By applying an HPLC-based cleanup procedure to wax extracts of pine needles, a high selectivity toward PCB was obtained. High precision and accuracy was achieved, as well as high relative (91-108 +/- 4-8%) and absolute overall recoveries (81 +/- 14%). Pine needle wax from the central and northern parts of Europe were examined. High concentrations of PCBs with a profile shifted toward low molecular species were found in Western Germany (SIGMA 9 CBs = 47 ng/g of wax) when compared to the other investigated geographical sites (SIGMA 9 CBs = 4-7 ng/g of wax).
Article
In this study, the leaves, roots, soil, and associated microorganisms of plants have been evaluated as a possible means of reducing indoor air pollutants. Additionally, a novel approach of using plant systems for removing high concentrations of indoor air pollutants such as cigarette smoke, organic solvents, and possibly radon has been designed from this work. This air filter design combines plants with an activated carbon filter. The rationale for this design, which evolved from wastewater treatment studies, is based on moving large volumes of contaminated air through an activated carbon bed where smoke, organic chemicals, pathogenic microorganisms (if present), and possibly radon are absorbed by the carbon filter. Plant roots and their associated microorganisms then destroy the pathogenic viruses, bacteria, and the organic chemicals, eventually converting all of these air pollutants into new plant tissue. It is believed that the decayed radon products would be taken up the plant roots and retained in the plant tissue.
Article
The uptake of 14C from various 14C-labeled organic chemicals from different chemical classes by barley and cress seedlings from soil was studied for 7 days in a closed aerated laboratory apparatus. Uptake by roots and by leaves via the air was determined separately. Although comparative long-term outdoor studies showed that an equilibrium is not reached within a short time period, plant concentration factors after 7 days could be correlated to some physicochemical and structural substance properties. Barley root concentration factors due to root uptake, expressed as concentration in roots divided by concentration in soil, gave a fairly good negative correlation to adsorption coefficients based on soil organic carbon. Barley root concentration factors, expressed as concentration in roots divided by concentration in soil liquid, gave a positive correlation to the n-octanol/water partition coefficients. Uptake of chemicals by barley leaves via air was strongly positively correlated to volatilization of chemicals from soil. Both root and foliar uptake by barley could be correlated well to the molecular weight of 14 chemicals. Uptake of chemicals by cress differed from that by barley, and correlations to physicochemical substance properties mostly were poor.
Article
Monocylic aromatic hydrocarbons (MAHs: benzene, toluene, ehtylbenzene and xylenes) were isolated from fruit and vegetables using a solvent extraction technique. GC-MS (with selected-ion monitoring mode) was applied for determination of the isolated pollutants. It was observed that uptake of MAHs depends on the species and takes place in different morphological parts of the biological material. The highest concentrations of MAHs were found in parsley leaves (m- and p-xylene) and in orange peel (toluene). Estimation of the daily human exposure to MAHs through eating contaminated fruit and vegetables was performed.
Article
The [1-6(14)C]benzene and [1-(14)C]toluene vapors penetrate into hypostomatous leaves of Acer campestre, Malus domestica, and Vitis vinifera from both sides, whereas hydrocarbons are more intensively absorbed by the stomatiferous side and more actively taken up by young leaves. Benzene and toluene conversion in leaves occurs with the aromatic ring cleavage and their carbon atoms are mainly incorporated into nonvolatile organic acids, while their incorporation into amino acids is less intensive. Intact spinach chloroplasts oxidize benzene, and this process is strongly stimulated in light. Oxidation of benzene by spinach chloroplasts or by enzyme preparation from spinach leaves is almost completely inhibited by 8-oxyquinoline or sodium diethyldithiocarbamate, and slightly affected by alpha, alpha'-dipyridyl. Benzene oxidation by enzyme preparation is significantly stimulated by NADH and NADPH; in their presence, the benzene hydroxylation product, phenol, is formed in a determinable amount. It is supposed that the enzyme performing the first step of oxidative transformation of benzene in plant leaves contains copper as the prosthetic group.
Article
In this study apple, blackberry and cucumber crops were exposed to elevated levels of benzene under controlled conditions. Benzene was retained in fruits of all crops, but only accumulated in leaves of blackberries and apples. The retention by cucumber fruits is suggested to result from the longer pathway for the desorption of benzene as a consequence of their increased tissue depth compared to leaves. The process of accumulation in blackberry and apple leaves is unknown. The ingestion of benzene via the food-chain pathway on the basis of this study is concluded not to be significant.
Article
Organic xenobiotics absorbed by roots and leaves of higher plants are translocated by different physiological mechanisms. The following pathways of xenobiotic detoxication have been observed in higher plants: conjugation with such endogenous compounds as peptides, sugars, amino acids, and organic acids; oxidative degradation and consequent oxidation of xenobiotics with the final participation of their carbon atoms in regular cell metabolism. The small parts of xenobiotics are excreted maintaining their original structure and configuration. Enzymes catalyze oxidative degradation of xenobiotics from the initial hydroxylation to their deep oxidation. The wide intracellular distribution and inductive nature of oxidative enzymes lead to the high detoxication ability. With plant aging, transformation of the monooxygenase system into peroxidase takes place. Once in the cells, xenobiotics are incorporated into different cell organelles. All xenobiotics examined are characterized by a negative effect on cell ultrastructure. The penetration of high doses of xenobiotics into plant cells leads to significant deviations from the norm and, in some cases, even to the complete cell destruction and plant death.
Article
The epidemiologic literature on benzene exposure and leukemia in the MEDLINE and TOXNET databases was examined through October 2004 using the keywords "benzene", "leukemia" and "adverse health effects". This search was complemented by reviewing the reference lists from extant literature reviews and criteria documents on benzene. Published studies were characterized according to the type of industry studied and design, exposure assessment, disease classification, and control for confounding variables. Study design consisted of either cohort studies or case-control studies, which were further categorized into population-based and nested case-control studies. Disease classification considered the source of diagnostic information, whether there was clinical confirmation from medical records or histopathological, morphological and/or cytogenetic reviews, and as to whether the International Classification of Diseases (ICD) or the French-American-British (FAB) schemes were used (no studies used the Revised European-American Lymphoma (REAL) classification scheme). Nine cohort and 13 case-control studies met inclusion criteria for this review. High and significant acute myeloid leukemia risks with positive dose response relationships were identified across study designs, particularly in the "well-conducted" cohort studies and especially in more highly exposed workers in rubber, shoe, and paint industries. Risks for chronic lymphocytic leukemia (CLL) tended to show elevations in nested case-control studies, with possible dose response relationships in at least two of the three studies. However, cohort studies on CLL show no such risks. Data for chronic myeloid leukemia and acute lymphocytic leukemia are sparse and inconclusive.
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