ArticleLiterature Review

Black carbon: The reverse of its dark side

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  • Norwegian Geotechnical Institute and Norwegian University of Life Sciences
Article

Black carbon: The reverse of its dark side

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Abstract

The emission of black carbon is known to cause major environmental problems. Black carbon particles contribute to global warming, carry carcinogenic compounds and cause serious health risks. Here, we show another side of the coin. We review evidence that black carbon may strongly reduce the risk posed by organic contaminants in sediments and soils. Extremely efficient sorption to black carbon pulls highly toxic polycyclic aromatic hydrocarbons, polychlorinated biphenyls, dioxins, polybrominated diphenylethers and pesticides into sediments and soils. This increased sorption is general, but strongest for planar (most toxic) compounds at environmentally relevant, low aqueous concentrations. Black carbon generally comprises about 9% of total organic carbon in aquatic sediments (median value of 300 sediments), and then may reduce uptake in organisms by up to two orders of magnitude. This implies that current environmental risk assessment systems for these contaminants may be unnecessarily safe.

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... The reduction in 2-4-ring PAHs ranged from 44 to 58% (Fig. 4A-C). The observed reduction in the content of 5-and 6ring PAHs was probably associated with the processes of sequestration or bound residue formation (Alexander, 2000), which substantially reduce the content of freely dissolved PAHs and are dependent on black carbon/soot (Koelmans et al., 2006). ...
... These relationships demonstrate that an increase in C and specific surface area reduced the range of PAH losses, which may suggest that the primary factor causing PAH losses was the process of biological degradation limited by the availability of PAHs. It is known that the specific surface area and C content determine the bioavailability of contaminants and this in turn determines their prone to biodegradation (Alexander, 2000;Pignatello and Xing, 1996;Koelmans et al., 2006). ...
... Both materials are rich in organic matter, which influences the sequestration of contaminants and in consequence their immobilization, thus contributing to decreased bioavailability and reduced toxicity (Alexander, 2000). This process is affected by organic matter, in particular black carbon and carbon with high aromaticity (Koelmans et al., 2006) that is predominant in biochar (Lehmann and Joseph, 2015). Biochar is more stable than sewage sludge, in which organic matter usually mineralizes within several months from its incorporation into soil (Terry et al., 1979;Rowell et al., 2001). ...
Article
Soils can be contaminated with polycyclic aromatic hydrocarbons (PAHs) when either sewage sludge (SSL) or biochar (BC) are used. There are no comparative studies regarding the effects of soil amendment with SSL or BC on the persistence, bioavailability and toxicity of PAHs. This research compared the persistence of PAHs (based on the extractable content, Ctot) and their bioavailability (freely dissolved, Cfree) as well as the toxicity (solid phase: Phytotoxkit F with Lepidium sativum and the Collembolan test with Folsomia candida; leachates: Phytotestkit F with L. sativum and Microtox® with Aliivibrio fischeri) of soil amended with SSL or with SSL-derived BCs. BCs were produced from three different sewage sludges at a temperature of 500 °C. SSLs or BCs were added to the soil at a rate of 1% (30 t/ha). Adding SSL to the soil increased more the PAH content in it than after BC application, which was associated with a higher content of PAHs in SSL. Losses of Σ16 Ctot and Cfree PAHs were higher than those observed for biochar only in the case of one SSL. In the other cases, PAH losses were either higher for biochar or did not differ significantly between SSL and BC. On the other hand, the analysis of the individual groups of PAHs showed significant differences between SSL and BC, both for Ctot and Cfree. Nonetheless, these differences were largely driven by the type of sewage sludge and biochar. Only in the case of root growth inhibition the toxicity higher was for the SSL-amended soils than for the BC-amended ones. In the other cases, varying results were observed which were determined by the type of sewage sludge/biochar, similarly to PAH losses.
... Major disadvantages in using field-collected sediments rely on the varying physicochemical properties of natural sediments, primarily organic matter, that may affect the partitioning of organic chemicals. In particular, several studies have evidenced the significant role of black carbon (BC) as a better adsorbent phase for organic pollutants as compared with other organic carbon sources in the sediments, including humic/fulvic substances, lipoproteins and lignin (Lohmann et al. 2005;Koelmans et al. 2006;Werner et al. 2010). Accordingly, the BC partition coefficients (K BC ) calculated for PAHs, polychlorinated biphenyls (PCBs) and other organochlorine pollutants are relevantly higher compared to the organic carbon partition coefficients (K OC ) usually used for predicting partitioning (Cornelissen et al. 2004;Lohmann et al. 2005;Koelmans et al. 2006;Zhang et al. 2008;Ali et al. 2016). ...
... In particular, several studies have evidenced the significant role of black carbon (BC) as a better adsorbent phase for organic pollutants as compared with other organic carbon sources in the sediments, including humic/fulvic substances, lipoproteins and lignin (Lohmann et al. 2005;Koelmans et al. 2006;Werner et al. 2010). Accordingly, the BC partition coefficients (K BC ) calculated for PAHs, polychlorinated biphenyls (PCBs) and other organochlorine pollutants are relevantly higher compared to the organic carbon partition coefficients (K OC ) usually used for predicting partitioning (Cornelissen et al. 2004;Lohmann et al. 2005;Koelmans et al. 2006;Zhang et al. 2008;Ali et al. 2016). Consequently, BC often resulted as the organic fraction controlling partitioning, bioaccumulation and toxicity of organic pollutants (Jonker et al. 2004;Sundelin et al. 2004;Koelmans et al. 2006;Sinche et al. 2018). ...
... Accordingly, the BC partition coefficients (K BC ) calculated for PAHs, polychlorinated biphenyls (PCBs) and other organochlorine pollutants are relevantly higher compared to the organic carbon partition coefficients (K OC ) usually used for predicting partitioning (Cornelissen et al. 2004;Lohmann et al. 2005;Koelmans et al. 2006;Zhang et al. 2008;Ali et al. 2016). Consequently, BC often resulted as the organic fraction controlling partitioning, bioaccumulation and toxicity of organic pollutants (Jonker et al. 2004;Sundelin et al. 2004;Koelmans et al. 2006;Sinche et al. 2018). As a result, even slight differences in the BC fraction (including soot, char and coals) may lead to sharp variations in the freely dissolved concentration (C free ) of a hydrophobic toxicant and complicate comparing the results among different tests and studies. ...
Article
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Laboratory testing with spiked sediments with organic contaminants is a valuable tool for ecotoxicologists to study specific processes such as effects of known concentrations of toxicants, interactions of the toxicants with sediment and biota, and uptake kinetics. Since spiking of the sediment may be performed by using different strategies, a plethora of procedures was proposed in the literature for spiking organic chemicals onto sediments to perform ecotoxicological analyses. In this paper, we reviewed the scientific literature intending to characterise the kind of substrates that were used for spiking (i.e. artificial or field-collected sediment), how the substrates were handled before spiking and amended with the organic chemical, how the spiked sediment was mixed to allow the homogenisation of the chemical on the substrate and finally how long the spiked sediment was allowed to equilibrate before testing. What emerged from this review is that the choice of the test species, the testing procedures and the physicochemical properties of the organic contaminant are the primary driving factors affecting the selection of substrate type, sediment handling procedures, solvent carrier and mixing method. Finally, we provide recommendations concerning storage and characterization of the substrate, equilibrium times and verification of both equilibration and homogeneity.
... Another means of determining sediment quality, is by measuring its amount of black carbon (BC)-the carbonaceous residue of incomplete combustion of organic matter and includes compounds such as charred biomass and soot. 19 Numerous studies of sediment carbon have demonstrated the ubiquitous presence of BC in the environment. [19][20][21] For instance, black carbon is deposited into marine sediments via rivers and (or) atmospheric transport mechanisms. ...
... 19 Numerous studies of sediment carbon have demonstrated the ubiquitous presence of BC in the environment. [19][20][21] For instance, black carbon is deposited into marine sediments via rivers and (or) atmospheric transport mechanisms. 20 Previous studies have shown that BC accounts for 4-22% of marine dissolved organic matter and 9% of TOC in sediments worldwide. ...
... 20 Previous studies have shown that BC accounts for 4-22% of marine dissolved organic matter and 9% of TOC in sediments worldwide. 19,21 These compounds are resistant to thermal or chemical degradation, and their resistivity to breakdown makes BC representative of a carbon sink in the environment. [22][23][24] Additionally, BC is resistant to microbial breakdown preventing its use as a nutrient source in the case of BMFC's. ...
Article
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The benthic microbial fuel cell (BMFC) is a promising technology for harvesting renewable energy from marine littoral environments. The scientific community has researched BMFC technology for well over a decade, but the in situ performance remains challenging. To address this challenge, BMFC power experiments were performed on sediment collected from San Diego Bay (CA, USA), La Spezia (Italy) and Honolulu (HI, USA) in the ever-changing littoral environment. Analysis of BMFC laboratory data found the power density varied substantially across 11 sites in San Diego Bay. In addition, data from experiments repeated at four locations in San Diego Bay showed significant differences between experiments performed in 2014, 2016 and 2019. Multivariable linear analysis showed BMFC 90 day cumulative power density was positively correlated with the total organic carbon (p < 0.05) and negatively correlated with the black carbon in the sediment (p < 0.05). Regression coefficients trained on the San Diego Bay data from 2014 facilitated accurate predictions of BMFC performance in 2016 and 2019. The modeling paradigm accurately explained variations in BMFC power performance in La Spezia and showed sediment parameters can impact BMFC performance differently across geographic regions. The results demonstrate a great potential to use sediment parameters and statistical modeling to predict BMFC power performance prior to deployment in oceanographic environments, thereby reducing cost, work force and resources.
... Aerosols can also influence UHI intensity. Urban aerosols are typically in the form of black carbon that are generated from the incomplete combustion of vehicular and industrial fuels (Koelmans et al., 2006). Black carbon aerosols are strong absorbers of solar radiation (Jacobson, 2001;Ramachandran and Kedia, 2010); therefore, they can cool the surface, but warm the atmosphere during daytime (Lacis and Mishchenko, 1995;Cusack et al., 1998;Qian et al., 2003Qian et al., , 2006. ...
... Urban areas typically have more pollutant aerosols than non-urban (Tie and Cao, 2009;Kanakidou et al., 2011), which are typically in the form of black carbon (BC). BC aerosols are generated from the incomplete combustion of vehicular and industrial fuels (Koelmans et al., 2006) and have strong solar radiation absorption properties (Jacobson, 2001;Ramachandran and Kedia, 2010), and thus can reduce land surface temperature (LST) during the daytime (Cusack et al., 1998;Lacis and Mishchenko, 1995;Qian et al., 2003Qian et al., , 2006. Jin et al. (2010) recently showed that a high aerosol optical depth (AOD) can reduce absorption of sunlight at the surface by 40-100 Wm -2 and reduce LST over urban areas by 1-2 K when compared to non-urban surroundings over Beijing. ...
... Urban LST can decrease due to aerosols' ability to absorb and scatter visible and near-infrared radiation. Typically, more pollutants are concentrated in urban areas than non-urban areas (Tie and Cao, 2009;Kanakidou et al., 2011), and they are usually in the form of black carbon that are generated from the incomplete combustion of vehicular and industrial fuels (Koelmans et al., 2006). Black carbon aerosols are strong absorbers of solar radiation (Jacobson, 2001;Ramachandran and Kedia, 2010). ...
Thesis
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The urban heat island (UHI) effect refers to how urban surfaces tend to be warmer than nearby non-urban areas due to less vegetation and other processes. UHIs can increase the risk of heat and respiratory illnesses. Since every city is unique, UHIs should be studied on a local-scale. One particular city that has not had its UHI comprehensively evaluated is Bengaluru, India. Bengaluru was once known as the “Garden City” of India due to a wide presence of gardens and public parks, but is now known as the “Silicon City” of India due to the overwhelming presence of the information technology industry. This dissertation aims to investigate Bengaluru’s UHI. First, the UHI was analyzed during the dry (December-January-February; DJF) and wet (August-September-October; ASO) seasons during day and night using land surface temperature (LST) data from the MODerate Resolution Imaging Spectroradiometer (MODIS). Results showed that the 2003–2018 mean UHI intensity was highest for DJF nighttime (1.43°C), followed by ASO daytime (1.14°C), ASO nighttime (1.02°C), and DJF daytime (–0.60°C). It was hypothesized that increasing urban aerosols may explain the negative UHI in DJF daytime since aerosols can absorb and scatter solar radiation and have a long residence time during the dry season. To better understand the causes of the UHI, an investigation of the relative importance of the leading controlling factors was explored using multiple linear regression and the random forest. The variables analyzed included albedo, aerosol optical depth (AOD), enhanced vegetation index (EVI), latent heat, soil moisture, specific humidity, and wind speed, which were chosen given Bengaluru’s tropical, moisture-rich location and since much of the city used to be covered by vegetation, but now by buildings, and that urban aerosols are increasing. Both approaches showed that EVI is more important than AOD. Therefore, the presence of aerosols is high enough to cancel an UHI that would otherwise occur in DJF daytime due to low vegetation. Next, the Weather Research and Forecasting (WRF) model was evaluated for its ability in simulating LST over Bengaluru and its sensitivity to urban canopy model (UCM) and planetary boundary layer (PBL) schemes. By comparing the simulations to MODIS LST, results showed that urban LST was more sensitive to UCM choice than PBL scheme and the use of an UCM reduced urban LST biases, which led to improved simulations of the UHI. For the best case, urban LST was underestimated by less than 1°C during DJF day and night, and was overestimated by 1.88°C and 0.08°C in ASO day and night. In general, the single-layer UCM (SLUCM) had the least bias for urban LST and UHI intensity. Different UCMs calculate radiative and surface fluxes differently, which could lead to distinct urban LST biases. During daytime, using No-UCM produced a near-zero latent heat flux and the multi-layer UCM (MLUCM) trapped too much shortwave and longwave radiation, both resulting in large, positive urban LST biases. During nighttime, the MLUCM had a negative urban LST bias due to too much longwave radiation reflecting between buildings, causing the lower atmosphere to be warmer than the surface. WRF experiments were then ran with perturbed vegetation cover by changing the control urban fraction of 0.90 by +10%, –10%, –20%, and –30%, where decreases represent greening. The responses in LST, UHI intensity, latent heat (LH), sensible heat (SH), and ground heat (GH) were analyzed. As expected, increased vegetation caused a decrease in LST, UHI intensity, SH, GH, and an increase in LH, and vice versa for a decrease in vegetation. For a –10% change in urban fraction, the mean UHI intensity decreased the most in DJF nighttime (–0.19°C), followed by ASO nighttime (–0.13°C), DJF daytime (–0.11°C), and ASO daytime (–0.10°C). DJF nighttime had the highest mean UHI intensity in the control run (1.70°C), was the most sensitive to changes in urban fraction, and was the only case with a significant UHI intensity mean change for a 10% decrease in urban fraction. Therefore, increasing vegetation by a small amount could have major benefits.
... Pyrogenic carbonaceous matter (PCM) refers to the pyrolysis products of fresh or fossilized biomass, including environmental black carbon (e.g., fossil fuel soot and chars) and engineered carbons (e.g., graphene, biochar, and powdered activated carbon (PAC)) [1,2]. Traditionally, PCM is considered a passive adsorbent for binding pollutants or providing microbes with an inert surface to grow [3][4][5][6][7][8][9]. Recently, a small but growing body of literature reports that PCM is intrinsically reactive and can participate in various reactions critical to biogeochemical processes [10][11][12], climate change [13,14], and contaminant transformation [15][16][17][18][19]. ...
Article
We employed a polymer network to understand what properties of pyrogenic carbonaceous matter (PCM; e.g., activated carbon) confer its reactivity, which we hereinafter referred to as PCM-like polymers (PLP). This approach allows us to delineate the role of functional groups and micropore characteristics using 2,4,6-trinitrotoluene (TNT) as a model contaminant. Six PLP were synthesized via cross-coupling chemistry with specific functionality (-OH, -NH2, -N(CH3)2, or -N(CH3)3⁺) and pore characteristics (mesopore, micropore). Results suggest that PCM functionality catalyzed the reaction by: (1) serving as a weak base (-OH, -NH2) to attack TNT, or (2) accumulating OH⁻ near PCM surfaces (-N(CH3)3⁺). Additionally, TNT hydrolysis rates, pH and co-ion effects, and products were monitored. Microporous PLP accelerated TNT decay compared to its mesoporous counterpart, as further supported by molecular dynamics modeling results. We also demonstrated that quaternary ammonium-modified activated carbon enhanced TNT hydrolysis. These findings have broad implications for pollutant abatement and catalyst design.
... É essa capacidade de adsorção que regula em grande parte a exposição dos HPA que estão ligados às partículas desses materiais. Para Cornelissen e Gustafsson (2004) e Koelmans et al. (2006), essa forte sorção pode ser responsável por altos níveis de HPA em partículas pirogênicas. Muitos dos HPA encontrados no biochar são classificados como poluentes prioritários e são duramente regulados pela Agência de Proteção Ambiental dos Estados Unidos, devido às suas propriedades carcinogênicas, mutagênicas ou teratogênicas (SIMONEIT, 1998;SIMONEIT, 2002;ABRANJO et al., 2003). ...
Conference Paper
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O gerenciamento do lodo de esgoto é um dos principais problemas na gestão de resíduos da União Europeia. Desta forma, nota-se um crescimento na tendência de reaproveitamento desse tipo de despejo, refletida nas alterações recentes da legislação que regula o seu tratamento e disposição final, e em acordo com os princípios da economia circular. Os métodos térmicos de tratamento têm ganhado visibilidade, dentre eles, a pirólise que gera como produto secundário biomassa carbonizada, o biochar ou biocarvão. O processo de pirólise, aonde ocorre combustão incompleta de materiais orgânicos, é responsável pela geração de hidrocarbonetos policíclicos aromáticos (HPA), compostos que apresentam propriedades tóxicas, mutagênicas e/ou cancerígenas. Por meio da determinação das concentrações finais de HPA em amostras de biochar, o trabalho visa avaliar o método de pirólise por micro-ondas como possível tratamento para a reinserção do lodo de esgoto no ciclo biológico. O biochar é um material rico em carbono de origem pirogênica, que contribui com a melhoria dos atributos do solo em função de suas características físico-químicas (Mayer et al.,2016; Petter e Madari,2012). Os HPA são gerados principalmente durante a combustão incompleta de materiais orgânicos. Muitos possuem propriedades tóxicas, mutagênicas e/ou cancerígenas (Abdel-Shafy e Mansour,2016). Devido à presença potencial dessas substâncias, o biochar deve atender à frequência de teste de avaliação de substâncias tóxicas e apresentar soma total de HPA abaixo de 6 mg/kg (IBI,2015). O lodo de esgoto foi pirolisado em uma planta piloto, no Centro de pesquisa AdMas, Universidade Tecnológica de Brno – República Tcheca, pelo método de micro-ondas. Foram utilizados diferentes tempos de residência e temperaturas, durante a pirólise. Para a extração dos HPA das amostras de biochar, foi utilizado um equipamento de Extração com Solvente Pressurizado e a leitura final dessas amostras foi feita meio de um cromatógrafo gasoso- espectrômetro de massa. Para a extração com solvente pressurizado (ESP) foram testados três programas para a extração dos HPAs do biochar, devido à similaridade dos resultados foi escolhido o que consistia em 2 ciclos de 15 minutos. Já para a análise das amostras de biochar proveniente do lodo de esgoto pirolisado, o valor analisado referiu-se à soma dos 16 HPA considerados prioritários pela Agência de Proteção Ambiental dos Estados Unidos (US EPA). Sendo que a amostra com maior concentração de HPA, apresentou soma total de 5,15 mg/kg, enquanto a com menor concentração apresentou soma de 1,88 mg/kg. Os resultados obtidos, revelaram que o tratamento por meio de pirólise por micro-ondas foi suficiente para manter, no biochar, as concentrações finais de hidrocarbonetos aromáticos policíclicos de acordo com a legislação vigente, abaixo de 6mg.kg-1. O que comprova o potencial que o biochar apresenta como processo de retorno dos resíduos do tratamento de efluentes para o ciclo biológico, como condicionante de solo na agricultura. Observou-se também, a necessidade de mais estudos sobre o tema, inclusive a validação dos métodos de análise, que possibilitem a obtenção de resultados mais robustos.
... Black carbon (BC), is a component of atmospheric particulate matter (PM) and is described as a solid pure carbon material formed during combustion. It is emitted during the incomplete combustion of fossil fuels, and biomass burning [1] and absorbs at all wavelengths of solar radiation [2]. It is usually co-emitted with other organic matter. ...
... Urban LST can decrease due to the ability of aerosols to absorb and scatter visible and near-infrared radiation. Typically, more pollutants are concentrated in urban areas than non-urban areas (Tie and Cao, 2009;Kanakidou et al., 2011), and they are usually in the form of black carbon that are generated from the incomplete combustion of vehicular and industrial fuels (Koelmans et al., 2006). Black carbon aerosols are strong absorbers of solar radiation (Jacobson, 2001;Ramachandran and Kedia, 2010). ...
Article
Urbanization can induce land cover changes that impact land surface temperature (LST). Many factors can influence the magnitude of urban heat, such as vegetation and aerosols. This work uses linear correlation, composite analysis, multiple linear regression, and random forest to determine the leading controls on urban LST of Bengaluru, India in the dry and wet seasons during daytime and nighttime from 2003-2018 using data from the MODerate Resolution Imaging Spectroradiometer and the European Centre for Medium-Range Forecasts ERA5 reanalysis. Results show that for the dry and wet season daytime, vegetation was the leading factor (linear correlation R=-0.74 and R=-0.34 with urban LST) since reduced vegetation limits evaporative cooling. For the dry season nighttime, vegetation was the leading factor (R=-0.52). Limited evaporative cooling during daytime can increase surface heat retention at night. For the wet season nighttime, specific humidity was the leading factor (R=0.21) since increased water vapor enhances downward longwave radiation and warms the surface. Therefore, urban heat is primarily controlled by vegetation in Bengaluru. However, since vegetation and specific humidity are related, mitigation strategies that increase vegetation must not increase water vapor substantially , otherwise urban heat may amplify during the wet season nighttime.
... Yet the separate effects of each PM 2:5 component (sulfates, nitrate, ammonium, organics, metals, etc.) are rarely quantified (Beelen et al. 2015;Ostro et al. 2011;Raaschou-Nielsen et al. 2016). Black carbon (BC), a component of PM 2:5 , comes from incomplete combustion processes, mainly from anthropogenic sources such as fossil fuel or biomass burning (Chylek et al. 2015;Koelmans et al. 2006). The first health concerns about exposure to BC appeared decades ago (Mumford et al. 1990); since then, reports have accumulated linking exposure to BC with increased morbidity and mortality, including lung cancer mortality (Anenberg et al. 2012;Grahame et al. 2014;Hvidtfeldt et al. 2019;Yang et al. 2019), lower lung function and slower cognitive development in children (Paunescu et al. 2019;Sunyer et al. 2015), increased bone loss , and decreased cognitive functions in the elderly Wurth et al. 2018). ...
Article
Background: Black carbon (BC), a component of fine particulate matter [particles with an aerodynamic diameter ≤2.5 μm (PM2.5)], may contribute to carcinogenic effects of air pollution. Until recently however, there has been little evidence to evaluate this hypothesis. Objective: This study aimed to estimate the associations between long-term exposure to BC and risk of cancer. This study was conducted within the French Gazel cohort of 20,625 subjects. Methods: We assessed exposure to BC by linking subjects’ histories of residential addresses to a map of European black carbon levels in 2010 with back- and forward-extrapolation between 1989 and 2015. We used extended Cox models, with attained age as time-scale and time-varying cumulative exposure to BC, adjusted for relevant sociodemographic and lifestyle variables. To consider latency between exposure and cancer diagnosis, we implemented a 10-y lag, and as a sensitivity analysis, a lag of 2 y. To isolate the effect of BC from that of total PM2.5, we regressed BC on PM2.5 and used the residuals as the exposure variable. Results: During the 26-y follow-up period, there were 3,711 incident cancer cases (all sites combined) and 349 incident lung cancers. Median baseline exposure in 1989 was 2.65 10−5/m [interquartile range (IQR): 2.23–3.33], which generally slightly decreased over time. Using 10 y as a lag-time in our models, the adjusted hazard ratio per each IQR increase of the natural log-transformed cumulative BC was 1.17 (95% confidence interval: 1.06, 1.29) for all-sites cancer combined and 1.31 (0.93, 1.83) for lung cancer. Associations with BC residuals were also positive for both outcomes. Using 2 y as a lag-time, the results were similar. Discussion: Our findings for a cohort of French adults suggest that BC may partly explain the association between PM2.5 and lung cancer. Additional studies are needed to confirm our results and further disentangle the effects of BC, total PM2.5, and other constituents.
... The occurrence of BC at high concentrations in surface soils has both positive and negative environmental implications. Owing to its high porosity BC and particularly the charcoal fraction can adsorb pollutants including PAH, PCB, dioxins and polybrominated diphenyl ethers (PBDE) as well as heavy metals thereby reducing their bioavailability to ecology and humans [58,62,[64][65][66]. Similarly, the presence of BC in soils has also been reported to increase cation exchange capacity as well as physically stabilise humic acids which in turn increases soil fertility [67]. ...
Article
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Total organic carbon (TOC), black carbon (BC), total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) were determined in 73 surface (0-2 cm) and subsurface (5-20 cm) soil samples taken from a 142 km2 area in Central London, UK. Soils were assessed to provide a baseline chemistry for site owners, developers, occupiers and regulators involved in understanding the potential risk to human health and the environment. TOC range was 1.75-11.85 % (mean 5.82 %), BC 3.72-32.71 mg.g -1 (mean 13.8 mg.g-1 ), TPH 72-4673 mg.g-1 (mean 443 mg.g-1 ), Σ 16PAH 1.64-421.23 mg.g-1 (mean 47.99 mg.g-1 ) and Σ 7PCB 2.56-148.72 µg.kg-1 (mean 20.82 µg.kg-1 ). Surface soils were less polluted than sub-surface soils due to a decline in industry, power generation, coal burning and traffic. PAH and PCB showed a stronger affinity for BC than TOC and were higher than many other international cities. South east London (Greenwich, Woolwich, Deptford) had the highest PAH pollution. Source PAH ratios confirmed a combustion/urban road run-off origin with minor petroleum inputs. Random Forest spatial modelling (machine learning) revealed large scale pollution trends across London soils. Normal background concentrations (NBC) were calculated and compared to risk-based human health generic assessment criteria (GAC). Benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, and dibenzo[a]anthracene exceeded the Land Quality Management GACs for three land uses (residential, allotments and public open space near residential housing). The NBC determined for ∑7PCBs (110 µg.kg-1) and dioxin-like PCB 118 (59 µg.kg-1) exceeded the residential and allotment soil guideline values.
... The fossil fuel such as coal, oil combustion, burning of biomass, wood, etc are some major man-made sources of black carbon (BC) aerosol particles and have a warming effect as they absorb solar radiations. Authors (Koelmans et al., 2006) also indicated that black carbon acts as an important atmospheric greenhouse gas component and is emitted immensely at developing nations like China (Zhang et al., 2009), creating an important area of investigation. Sulphate is a very dominant aerosol that originate from industrial activities and causes decrease in surface temperature (Baker et al., 2015). ...
... Black carbon (BC) is the dominating light absorbing component of particulate, which is estimated to be the most important anthropogenic contributor to global warming after CO2 (Tami C Bond et al., 2013;Ramanathan and Carmichael, 2008) and is widely recognised as having adverse effects on human health of the exposed population (Grahame et al., 2014;Kandlikar et al., 2009;Koelmans et al., 2006;Shrestha et al., 2010). BC has impacts not only on the optical properties of clouds (Lohmann and Feichter, 2005;Riemer et al., 2010;Rose et al., 2011) but also atmospheric chemistry and dynamics (Deng et al., 2010;A Ding et al., 2016). ...
Article
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The Yangtze River region and cities along the river have severe deterioration of air quality due to urbanization and economic development. Black carbon (BC) has significant impacts on air quality and climate, however it is poorly characterised across the region. Here we report the first continuous measurements of BC and gaseous pollutants along the Yangtze River in wintertime, with an intensive observation period from 21 November to 4 December 2015, covering ∼7° longitude over the continent in China. The highly polluted periods (HPP) with NOx > 80 μg m‐3 indicated more localized emissions. At the western (longitude < 118°E) and eastern (longitude > 118°E) ends of the Yangtze river valley, the HPP events reduced, mostly since the western end was influenced by terrain height and regional transport, and the eastern end was influenced by easterly oceanic or westerly continental air masses. In these regions, BC core size decreased by 5‐19% during the HPP, and had modes of mass median diameter in the range 120‐180 nm, which was found to be predominately from local sources, contrasting with a more consistent mode ∼200 nm that was due to BC from mixed sources. A comparison of simultaneously measured data from the nearby monitoring stations along the river demonstrated a high consistency of PM2.5 over the river, which reflected the important regional impact on the particulate mass. This study evaluates the shipping emission and regional influence over the Yangtze River and may guide the policy maker on mitigating air pollution.
... The clear correspondence between PAH and BC in the Thames sediment cores may be due to an identical combustion source (co-emission) and/ or sorption of PAH onto BC (e.g. soot) surfaces and/or trapping within BC occlusions (Accardi-Dey and Gschwend, 2002; Cornelissen and Gustafsson, 2004;Koelmans et al., 2006). Overall, the strong association between PAH to BC supports the view that in many urban soils and sediments BC exerts a stronger control on sorption of organic pollutants, such as PAH, than the overall TOC (Accardi-Dey and Gschwend, 2002; Vane et al., 2021). ...
Article
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Sedimentary organic pollution in the urban reaches of the Thames estuary is changing from fossil fuel hydrocarbons to emerging synthetic chemicals. De-industrialisation of London was assessed in three cores from Chiswick (Ait/Eyot) mud island using pharmaceuticals, faecal sterols, hydrocarbons (TPH, PAH), Black Carbon (BC) and organotins (TBT). These ranked in the order; BC 7590-30219 mg/kg, mean 16,000 mg/kg > TPH 770–4301, mean 1316 mg/kg > Σ16PAH 6.93–107.64, mean 36.46 mg/kg > coprostanol 0.0091–0.42 mg/kg, mean of 0.146 mg/kg > pharmaceuticals 2.4–84.8 μg/kg, mean 25 μg/kg. Hydrocarbons co-varied down-profile revealing rise (1940s), peak (1950s -1960s) and fall (1980s) and an overall 3 to 25-fold decrease. In contrast, antibiotics, anti-inflammatory (ibuprofen, paracetamol) and hormone (17β-estradiol) increased 3 to 50-fold toward surface paralleling increasing use (1970s-2018). The anti-epileptics, carbamazepine and epoxcarbamazepine showed appreciable down-core mobility. Faecal sterols confirmed non-systematic incorporation of treated sewage. Comparison to UK sediment quality guidelines indicate exceedance of AL2 for PAH whereas TBT was below AL1.
... As the product of incomplete combustion of carbonaceous fuels such as fossil fuels and biofuels, BC is also the most harmful pollutant in PM 2.5 (Bond et al., 2013). Ding et al. (2016) revealed the "dome effect" of BC has exacerbated haze in megacities, jeopardizing human health (Koelmans et al., 2006). As measures of BC emission reduction have been proven effective in improving air quality worldwide , reducing BC emission would be a feasible win-win strategy for both climate change mitigation and air pollution control (Andreae, 2001;Bond and Sun, 2005;Hansen et al., 2000;Shindell et al., 2012). ...
Article
As the second largest factor contributing to global warming, black carbon (BC) is also the main cause of smog pollution in Chinese cities and has negative influence on residential health. In this paper, structural decomposition analysis (SDA) and structural path decomposition (SPD) are jointly used to identify the socioeconomic factors and critical supply chain paths driving consumption-based BC changes in Sichuan Province, which has become a main BC emission source since the implementation of “Western Development Strategy”. The SDA results show that economic growth contributes 75.02 kt emission increase. Emission intensity plays a critical role in emission reduction, which offsets the emission increase by 56.00 kt. The results of SPD identify that the major paths influencing BC emission changes are “Petroleum Processing→(Construction/Metal Smelting and Production/Machinery and Equipment)→Final Demand,” “Agriculture→(Food Production/Agriculture)→Final Demand,” and “Transportation→(Commercial and Institution)→Final Demand.” Socioeconomic drivers might pose a bidirectional impact on BC emission on different supply paths. The results reveal that BC reduction should emphasize reducing the emission intensity of the upstream sector, improving the production efficiency of the intermediate sector, and using cleaner alternatives in the downstream sectors on critical paths. The case of Sichuan may provide insights into the BC mitigation practices of other regions.
... One of these studies used adsorption with carbon-based materials, such as black carbon, activated carbon, carbon nanotubes, graphene, and graphene oxide, to remove PCBs from aqueous environments [10]. The strong affinity of PCBs to activated carbon has been demonstrated in numerous studies [11][12][13]. However, carbon nanotubes were used to obtain a better adsorption efficiency, increasing the efficiency up to 98% due to their high surface area of adsorption. ...
Article
This study theoretically and experimentally selected a membrane for application in a perstraction process for PCB-77 removal using COSMO-RS predictions. To validate COSMO-RS, different studies of pollutants were analysed and compared using the activity coefficient computed by COSMO-RS, and the experimental reported results were in accordance with the predicted thermodynamic parameters. Then, the main components in milk were optimised using TMoleX® to screen for different polymers. The screening revealed that polychloroprene, polybutadiene, and polyoctylmethylsiloxane had the lowest activity coefficients for PCB-77, and a high selectivity for other components in milk. The results obtained by COSMO-RS were compared with experiments using nitrocellulose, polydimethylsiloxane, polyether sulfones, and polystyrene, where the simulated values were validated. Finally, analysis of the membrane structures revealed that the best membrane to be applied in perstraction is polyoctylmethylsiloxane.
... Combustion of fossil fuels and deforestation have caused the concentration of CO 2 to increase by 43% after the industrialization (NOAA, 2017). In addition, black carbon is an important constituent of air borne particulate matter that is often emitted as product of incomplete combustion of fossil fuels and burning of biomass and biofuels (Koelmans et al, 2006). The amount of CO2 released by the combustion of 1 L of petrol and 1 L of diesel fuel varies depending on the chemical composition of the fuels, but it is around 2.36 kg and 2.60 kg, respectively. ...
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The present study was carried out to monitor the ambient concentrations of particulate matter and carbon dioxide caused by vehicular pollution in Srinagar City of Jammu and Kashmir, India, for a period of 12 months from June 2019 to May 2020 as the major contributions in these areas are due to vehicular movement. Out of five, four locations (viz. Dalgate, Jehangir Chowk, Parimpora and Pantha Chowk) had highest traffic density in the city and the fifth location (Shalimar) had low traffic volume. The sampling was done on every fortnight using AEROCET 831—aerosol mass monitor and CDM 901—CO2 monitor with each sampling being carried out three times a day, i.e. morning (9:00 am–10:30 am), afternoon (1:00 pm–2:30 pm) and evening (4:30 pm–6:00 pm) with three replications at each site based on the peak traffic hours. The results show that during the whole period, average PM1 concentrations ranged from 15.10 to 108.9 µg/m³, PM2.5 (28.70–577.50 µg/m³), PM4 (44.50–780.87 µg/m³), PM10 (57.13–1225.53 µg/m³), total suspended particulates (77.77–1410.27 µg/m³) and CO2 (332.4–655.0 ppm). The average concentrations of these parameters showed that the maximum PM1 concentration was found at Dalgate (53.77 µg/m³) and PM2.5 had its maximum average concentration at Jehangir Chowk (140.13 µg/m³). Other parameters like PM4, PM10, TSP and CO2 had a maximum average values at Jehangir Chowk (240.23 µg/m³, 633.40 µg/m³, 853.50 µg/m³ and 533.20 ppm, respectively). The pollution load was observed to be maximum during winter season followed by autumn, summer and spring. The lowest concentration of all pollutants except CO2 was observed in April 2020 and this might be due to COVID-19 lockdown observed in the country during the same period.
... Пестициды и гербицидыгидрофобные органические соединения антропогенного происхождения. В почвенном профиле данные органические вещества сорбируются как органическим веществом, исходно содержащимся в почве, так и биоуглем (Cornelissen et al., 2013;Kittelson Koelmans et al., 2006). Все виды углей и сажа обладают высокой сорбционной способностью, превышающей показатели всех углеродных соединений в почве в 10 -1000 раз (Chiou et al., 2004;Busch et al., 2012). ...
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Состояние почв лесных питомников является одним из лимитирующих факторов, оказывающих влияние на выход стандартного посадочного материала с 1 га площади. Проведена комплексная оценка почв действующих питомников Ленинградской области. Изучены механизмы воздействия биоугля на физические, биологические и агрохимические параметры типичных для Ленинградской области агродерново-подзолистых почв различного гранулометрического состава. Расширены современные представления о применении биоугля при выращивании сеянцев хвойных пород как в открытом, так и в закрытом грунте. Впервые установлено положительное влияние биоугля на плодородие почв лесных питомников, а также на биометрические показатели роста и развития сеянцев хвойных пород. Оценка роста и биометрических параметров проведена как в контролируемых условиях закрытого грунта (при выращивании на торфяных субстратах в теплице летнего типа с поликарбонатным покрытием), так и в посевных отделениях питомников. [The soil condition of forest nurseries is one of the limiting factors influencing the yield of standard planting material from 1 ha of area. A comprehensive assessment of soils of operating nurseries in the Leningrad region has been carried out. Mechanisms of influence of biochar on physical, biological and agrochemical parameters of typical for the Leningrad region agrodern-podzol soils of different granulometric composition have been studied. The modern concepts of biochar application in the cultivation of coniferous seedlings both in open and closed ground have been expanded. For the first time, a positive effect of biochar on the fertility of nursery soils as well as on the biometric indicators of growth and development of coniferous seedlings has been established. Evaluation of growth and biometric parameters was carried out both in controlled conditions of the closed ground (when growing on peat substrates in a summer-type greenhouse with a polycarbonate cover), and in the seedlings' nursery compartments.]
... Ample evidence in the last few years have confirmed that particulate and acid aerosols in the air are highly correlated with several respiratory diseases such as chronic respiratory illness, lung cancer, bronchial diseases, cardiovascular morbidity etc. (Dockery et al., 1993;Pope et al., 2002;Stieb et al., 2002). PM can be found in the atmosphere in the form of dust, fumes, mist, fog, smoke, soot, Black Carbon (BC), etc. Black Carbon contains PAH (Polynuclear Aromatic Hydrocarbon) which is carcinogenic to human health (Koelmans et al., 2006). ...
Thesis
As the cities in Bangladesh get more industrialized, more development projects are undertaken, making the surrounding air more polluted. The air pollution in major cities of Bangladesh has become quite acute in recent years. Among all components, PM2.5 is considered to be one of the major harmful elements. Due to its tiny particle size, it can enter the bloodstreams of respiratory tracts and even can cause death.Therefore, it is crucially needed to understand the particulate matter characteristics, to bring it down to a moderate level. Since, studies showed that, meteorology has significant influence on PM variation, approach has been taken in this study to understand the influence of meteorology on PM variation over the region of Bangladesh. Air quality and meteorological data from Department of Environment (DoE) for the period of 2013-2018 for eleven stations (CAMSs) of Bangladesh are collected. Among eleven existing stations, we perform analysis on eight available stations and the remaining three are discarded due to theirpoor-quality data. We perform annual and seasonal cross correlation analysis to identify major influential parameters on PM variation at different times of the year. We also perform multiple linear regression analysis (MLR) using interaction terms to understand the combined effect of meteorological parameters on PM. Annual cross correlation analysis shows that, wind speed, temperature,solar radiation and relative humidity are effective parameters for PM2.5 and wind speed, relative humidity,rainfall duration andrainfall are effective parameters for PM10variation. Wind speed, relative humidity,temperature, rainfall duration and rainfall amount show negative correlation with PM and solar radiationshow positive correlation with PM. Seasonal analysis shows that, low wind speed causes PM accumulation in winter and post-monsoon, whereas, high wind speed causesPM dilution in pre-monsoon and monsoon. Change in temperature can change boundary layer height and subsequently alter ambient PM. This effect of temperature is found to be effective throughout the year. However, bioaerosol formation in presence of temperature is observed during monsoon. Relative humidity is inversely correlated with PM and the correlation is highest in monsoon for majority of thestations. However, due to its location in coastal area and intrusion of sea aerosol,Chattogram shows weak correlation between relative humidity and PM in monsoon. Solar radiationshows positive correlation with PM throughout the year. The duration of rainfallis found to be more effective in PM removal compared to amount of rainfall. Highest negative correlation between precipitation and PM is observed inSylhet, since it is the region of highest consistent rainfall in Bangladesh. MLR analysis showed that local meteorology could explain up to 17% to 78% PM variation in major cities of Bangladesh. The interaction between temperature, relative humidity and wind speed and their combined effect are found to have major influence on PM for most of the stations. This study gives a comprehensive idea on how much influence meteorological parameters can have on PM variation in different cities in Bangladesh for different seasons. Findings of this study are expected to be helpful in decision making for adoption of pollution control measures and evaluating different climate change mitigation and adaptation approaches.
... Biochar is the pyrolysis product of biomass under a limited amount of oxygen (O 2 ) through the thermal decomposition of organic material (Lehmann and Joseph, 2012). One of the most important properties of biochar is the ability to absorb and retain organic and/or inorganic pollutants (Ahmad et al., 2014;Cao et al., 2011;Chen et al., 2015;Jiang et al., 2012;Koelmans et al., 2006;Li et al., 2020), reducing the bioavailability of environmental pollutants (Alhashimi and Aktas, 2017). Meanwhile, biochar can also benefit soil fertility (Major et al., 2010) and mitigate climate change (Sohi, 2012) at the same time via carbon sequestration. ...
Article
Plastic pollution has become a global threat in the natural environment, and an urgent remedial measure is needed to reduce the negative effects caused by plastic pollutants. In the current study, the effects of pyrolysis temperature (500 °C, 700 °C, and 900 °C) and aging on the adsorption of polystyrene nanoplastics (PSNPs) onto corncob biochar were systematically assessed with kinetic, isotherm, pH-dependent adsorption experiments, FTIR and XPS spectroscopy, and DLVO calculations. The oxidation was done with 5% of HNO3/H2SO4 to simulate long-term oxidative aging of biochar in the environment. The results showed that the specific surface area, hydrophobicity, and aromaticity of biochar increased with pyrolysis temperature, whereas the specific surface area and amounts of oxygen-containing groups increased after oxidation. The adsorption mechanism of PSNPs onto the biochar was explored based on the correlation between biochar properties and adsorption parameters derived from adsorption isotherms. Overall, the adsorption capacity of biochar for PSNPs increased with increased pyrolysis temperature and after aging. While the increase of specific surface area was considered the major factor leading to the increase of the adsorption, the variation in surface properties also played an important role. Pore filling, hydrophobic interaction, and hydrogen bonding may all be involved in PSNPs adsorption to biochar. However, the hydrophobic interaction might be more important for the fresh biochar, whereas hydrogen bonding involving oxygen-containing groups might make a bigger contribution to PSNPs adsorption to oxidized biochar. The pH experiments revealed that PSNPs adsorption decreased in general with the increase of pH, indicating that electrostatic repulsion played a vital role in the PSNPs adsorption process. The results of this study indicate that biochar can be potentially applied to immobilize plastic particles in terrestrial ecosystems such as in soil or groundwater, and the immobilization could be enhanced via artificial oxidation or aging of biochar in the natural environment.
... Moreover, the top 10 cited reviews related to sorption of organic pollutants on soils address environmental management (EM) (Ahmad et al., 2014;Beesley et al., 2011;Koelmans et al., 2006;Kookana et al., 2011;Rajapaksha et al., 2016), EF (Delle Site, 2001;Hanselman et al., 2003;Luthy et al., 1997;Pignatello and Xing, 1996) and specific knowledge (SK) generation (Keiluweit and Kleber, 2009), providing an excellent overview of relevant topics both for scientists and policymakers with an applied interdisciplinary focus. However, all these reviews lack direct or explicit use for policymakers and unknown similitude with local and global environmental issues, affecting the institutionalization and use of scientific evidence about sorption for environmental decisions and needs (Bilotta et al., 2015;Kano and Hayashi, 2021). ...
Article
There exists an increase of review articles of pollutant sorption on soils due to the relevance of this process in environmental fate. However, this information is not used to make environmental decisions. We conduct a scoping review to identify and categorize the state-of-the-art of pesticide sorption (organic pollutant model) and decision-making studies in 2015–2020 using databases (Web of Science, Scopus and ScieLo) to detect potential gaps and create a framework that guide the connection between scientific evidence and its institutionalization. We detect research gaps (inside sorption or decision-making studies) and evidence gaps (between sorption and decision-making) from literature based on five categories to describe sorption (sorbate-sorbent system, system variables to study the sorption process, objectives pursued by authors, experimental approaches to study the sorption process, and quantification of sorption) and four topics for regulatory contexts (sponsor contextualization, descriptive information, environmentally relevant issues and Sustainable Development Goals (SDGs)). The gaps included (i) unrelated study designs, (ii) unreliable causal mechanisms, (iii) unrelated SDGs, (iv) lack of collaboration, (v) lack of representativeness, (vi) lack of knowledge, (vii) lack of relevant studies, and (vii) unknown causal extrapolation. Our framework connected the gaps with relevant environmental issues and common research topics on sorption studies, including suggested solutions and inclusion of lacking SDG in literature. The framework can assist the science-policy interaction, promoting cooperation for different study designs, pollutant-soil systems, and socio-environmental applications, such as environmental fate and management, risk assessment, monitoring, remediation, and local regulations.
... As such, the term BC describes a continuum of particles from slightly charred biomass to highly condensed and refractory soot and graphite Hedges et al., 2000;Kuhlbusch and Crutzen, 1995). Slightly charred particles are generally dominated by small polycyclic aromatic hydrocarbons (PAHs) (2-7 rings) and labile carbon forms and, whereas soot particles are mainly comprised of gas phase re-condensed highly aromatic molecules (PAHs >7 rings) and stable carbon forms Koelmans et al., 2006;Meredith et al., 2012). Black carbon occurs ubiquitously in the environment, playing an important role in a wide range of biogeochemical processes (Talukdar et al., 2019;Bond et al., 2013;Flanner, 2013;Masiello, 2004), and it has been suggested that it may influence the turnover of more labile ecosystem-derived SOC, defined as decaying plant residues, soil biota and exudates (Liu et al., 2018;Edmondson et al., 2015;Liang et al., 2010;Major et al., 2010). ...
Article
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Soils hold three quarters of the total organic carbon (OC) stock in terrestrial ecosystems and yet we fundamentally lack detailed mechanistic understanding of the turnover of major soil OC pools. Black carbon (BC), the product of the incomplete combustion of fossil fuels and biomass, is ubiquitous in soils globally. Although BC is a major soil carbon pool, its effects on the global carbon cycle have not yet been resolved. Soil BC represents a large stable carbon pool turning over on geological timescales, but research suggests it can alter soil biogeochemical cycling including that of soil OC. Here, we established two soil microcosm experiments: experiment one added ¹³C OC to soil with and without added BC (soot or biochar) to investigate whether it suppresses OC mineralisation; experiment two added ¹³C BC (soot) to soil to establish whether it is mineralised in soil over a short timescale. Gases were sampled over six-months and analysed using isotope ratio mass spectrometry. In experiment one we found that the efflux of ¹³C OC from soil decreased over time, but the addition of soot to soil significantly reduced the mineralisation of OC from 32% of the total supplied without soot to 14% of the total supplied with soot. In contrast, there was not a significant difference after the addition of biochar in the flux of ¹³C from the OC added to the soil. In experiment two, we found that the efflux ¹³C from soil with added ¹³C soot significantly differed from the control, but this efflux declined over time. There was a cumulative loss of 0.17% ¹³C from soot over the experiment. These experimental results represent a step-change in understanding the influence of BC continuum on carbon dynamics, which has major consequences for the way we monitor and manage soils for carbon sequestration in future.
Article
Sulfate, nitrate and ammonium are the most abundant secondary inorganic aerosols (SIA) in atmospheric fine particle matter (PM2.5). Meteorological conditions, gas-particle transportation process, and aerosol acidity (pH) can influence SIA formation. In this study, we conducted semi-continuous measurements of water-soluble inorganic ions during a winter extreme pollution event (from January 9th to January 17th, 2015, average PM2.5 concentrations of ~250 μg m⁻³ and peak concentrations of ~700 μg m⁻³) in Xi'an to elucidate on the SIA formation mechanism. The hourly mean level of the total water-soluble ion was 137.4 μg m⁻³, accounting for 55.3% of PM2.5 on average. The dominant ions concentrations of SO4²⁻, NO3⁻ and NH4⁺ accounted for 15.8%, 19.0% and 13.2% of PM2.5 mass, respectively. PM2.5 was moderately acidic, with an average pH of 4.8 ± 0.4. Compared to the clean periods, sulfate content decreased by 6.9% during the polluted periods, while those of nitrate and ammonium increased by 2.2% and 5.0%, respectively. The increase in nitrogen oxidation ratios (NOR) and ammonia conversion ratio (NHR) from normal days to haze days were greater when comparison to sulfur oxidation ratios (SOR). In the polluted periods, sulfate and nitrate formations were facilitated by water content increase. Strong linear correlation coefficients between SOR (R² = 0.81) and NOR (R² = 0.55) with aerosol water content indicated that the gas-liquid reaction of SO2 and NO2 is the major pathway of sulfate and nitrate formation during severe haze episodes. In contrast, the NHR and aerosol water content exhibited a logarithmic relationship, which reveals that when water content was greater than 100 μg m⁻³, the gas-particle partitioning ratio of ammonium was basically unchanged following an increase in water content.
Article
Significant amounts of organic carbon derived from black carbon (BC) are transported annually through the Pearl River Estuary (PRE) in Southern China, into the continental shelf of the South China Sea. However, molecular composition and distribution of dissolved black carbon (DBC) compounds along the PRE are still rarely studied. In this work, dissolved organic matter isolated and extracted by solid phase extraction from water samples collected in summer along the PRE are studied and characterized by negative electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and with special attention paid to DBC molecules. The numbers and relative intensities of identified DBC molecules (CHOx class) decrease gradually with the salinity gradient from the upper reach to the open water. The DBC molecules accumulated with relatively high intensities in O7 and O9 classes in Site A and slightly shifted to O5, O7-8 classes in Site E along the PRE. Possible three or four rings of aromatic ring structure of DBCs, with hydroxyl and carboxy substituent groups are proposed. The relatively smaller sizes of DBCs are likely to have originated from relatively larger oxidized condensed aromatic structures of black carbon. The trend of DBC distribution along the estuary could be explained by DOM degradation in the mixing zone.
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The provenance, preponderance, mobilization/export potential, and environmental health effects of charred residues have been reviewed and discussed in the context of decoupling of biogeochemical DOC (and DON) cycling. The present review suggests that high anthropogenic inputs and enrichment of marine sediments by bulk terrigenous DOC (δ¹³C ~ -20 ‰ to -25‰) lead to high DOC/DON ratios (≥10), which correlate with seasonal hydrology and diagenetic events. The stability of refractory residues like pyrrole for black nitrogen (BN) and aromatic hydrocarbons for (BC) under pedogenic and diagenetic processes needs to be addressed, considering time lags between production and resuspension events. A variation in absolute values of δ¹⁵N (2.0 to 7.0 ‰) in organically sequestered marine sediments indicates complex sources of various nitrogen-enriched organic carbon (OC) and dynamic erosion processes. These natural events are signified by an OC/DBN ratio of 13.3 ± 3.5, often explained by variations in precursor organic materials. Complex biogeochemical evolution at forest and agricultural ecosystem levels, coupled with anthropogenic influences, renders δ¹⁵N values between -10 and 10 ‰, which are lower than in marine ecosystems (6 – 10 ‰). This article focuses on the interrelationship between DBC and DBN, their global features relative to transport and movement to aquatic bodies, and current methodologies that specifically explore aquatic and terrestrial cycling of DBC/DBN. The review also takes into account critical research gaps and highlights the challenges and opportunities for research on BC and BN dynamics in the environment. The quantitative contribution of BC and BN in the DOC of the hydrosphere and the corresponding pathway of DBC may be studied further to have more insight into the distribution of dissolved matter in the global ocean system.
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In this study, we present the application of a dual-isotope approach for the source apportionment of polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) in the East China Sea (ECS). The δ¹³C and δ²H isotope signatures of the PAHs were determined from surface sediments collected from the ECS. A Bayesian Markov chain Monte Carlo (MCMC) model was used to the environmental source identifications with dual-isotope PAHs data. The results indicate that the coal combustion source is predominant (with average of 41%) in the ECS. Liquid fossil fuels combustion, biomass combustion, and petrogenic sources account for 23%, 20%, and 12% of the total PAH burden, respectively. Additionally, we also determine the stable and radio carbon isotopes (δ¹³C and Δ¹⁴C) of total BC in sediment samples of the ECS. The results demonstrate the quantitative source apportionments for different sources, reflecting the contributions of fossil fuels (coal combustion and petroleum-related emissions), biomass (C3 and C4 plants) combustion, and rock-weathering sources. The fossil combustion in BC accounts for 67%, with 23% for biomass sources, meanwhile the rock weathering source in BC is an average of 10%. These results show a remarkable similarity and extensive homologies at source apportionment of PAHs and BC in the ECS, even though some differences in source mechanisms and processes. These findings on the environmental source apportionment will provide a reference for improved emission inventories, and will help to provide guidance for the efforts to mitigate environmental pollution in the coastal areas and marginal sea.
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Unplanned industrial and urban development are the main sources of increasing concentration of soot and heavy metals in the environment. These pollutants have instigated the deleterious impacts on the environment. Over the past few decades, many researchers have proposed different methods to bring improvement in the environmental quality. These methods include effective combustion techniques that produce less soot and the methods of using soot in the decontamination of environmental compartments polluted with the heavy metals. The aim of this paper is twofold. Firstly, we present a model of an eco-friendly cooking stove to overcome the problem of domestic soot emissions. The proposed model of stove uses a typical type of vented soot filtration hood which contains the soot particulate filters to effectively control soot emissions. Secondly, we study the remediation efficiency of plastic fuel derived soot for heavy metals lead (Pb), nickel (Ni), and chromium (Cr) from the aqueous solutions, contaminated soil, and wastewater samples. A series of batch adsorption experiments are conducted to analyze the effect of different parameters on the heavy metals uptake from aqueous solutions and wastewater samples. The effect of soot application on the heavy metals immobilization from the contaminated soil samples is also studied by using the EDTA extraction method. Experimental results reveal that pH 9.0 is optimal for the adsorption of heavy metals from the aqueous solutions. Soot application to the soil samples increased the pH and reduced 0.1 M EDTA extractable concentration of heavy metals. From the water samples, adsorption of heavy metals increased by increasing the contact time and maximum adsorption occurred at the optimum contact time of 3 hours. Moreover, the experimental data are well modeled through the Langmuir and Freundlich isotherm models. The overall effectiveness of soot in reducing the concentration of heavy metals from aqueous solutions, soil samples, and water samples is as follows: Pb (94.4%, 75%, and 90.5%), Ni (69.97%, 37.4%, and 69.8%), and Cr (61.3%, 37.5%, and 82.6%). It has been inferred from results of this study that soot has a great potential as a remediation tool for the environment excessively contaminated with heavy metals.
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Dehalogenation is one of the most important reactions for eliminating trace organic pollutants in natural and engineering systems. This study investigated the dehalogenation of a model organohalogen compound, triclosan (TCS), by aqueous biochars (a-BCs) (<450 nm). We found that TCS can be anaerobically degraded by reduced a-BCs with a pseudo first-order degradation rate constant of 0.0011–0.011 h–1. The 288 h degradation fraction of TCS correlated significantly with the amount of a-BC-bound electrons (0.055 ± 0.00024 to 0.11 ± 0.0016 mol e–/mol C) available for donation after 24 h of pre-reduction by Shewanella putrefaciens CN32. Within the reduction period, the recovery of chlorine based on residual TCS and generated Cl– ranged from 73.6 to 85.2%, implying that a major fraction of TCS was fully dechlorinated, together with mass spectroscopic analysis of possible degradation byproducts. Least-squares numerical fitting, accounting for the reactions of hydroquinones/semiquinones in a-BCs with TCS and byproducts, can simulate the reaction kinetics well (R² > 0.76) and suggest the first-step dechlorination as the rate-limiting step among the possible pathways. These results showcased that the reduced a-BCs can reductively degrade organohalogens with potential applications for wastewater treatment and groundwater remediation. While TCS was used as a model compound in this study, a-BC-based degradation can be likely applied to a range of redox-sensitive trace organic compounds.
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The problem of household air pollution (HAP) due to the use of inefficient cooking devices continues to affect the rural population of India. With the ongoing efforts to improve indoor air quality (IAQ) through intervention of clean cooking options it is imperative to assess these interventions in real world conditions before large scale rollouts. The present study is an attempt to assess the impact of three clean cooking solutions - induction stove (IS), forced draft cookstove (FDC) and a traditional cookstove with hood (TCH) in rural area of Solan, Himachal Pradesh in India. Using a cross-sectional study design mean 24-hr kitchen area concentration of PM2.5 and PM1, carbon monoxide (CO) along with cooking time black carbon (BC) were measured. A significant (p<0.05) reduction of >70% in mean 24-hr and cooking time concentrations of all the pollutants was observed in all three clean cooking interventions compared to the traditional cookstove. However, in case of IS the reduction in mean 24-hr PM2.5 and PM1 concentrations were 72% and 74% respectively which were much lower than nearly 100% reduction in CO and BC. Low cost interventions such as TCH were also found to improve IAQ significantly. However, higher BC fraction in PM in FDC indicated a scope for technological improvement in design of such stoves and a need for integrating BC as a stove performance indicator was also realized. Additionally, a comparative analysis using IAQ data from related studies highlighted the role of kitchen geometry and ambient air quality in causing variation in IAQ. So, for large scale community programmes and initiatives that aim to mitigate HAP it is important to have multi-pronged approach that takes into cognizance factors other than cookstove which impact IAQ.
Article
Black carbons (BCs) are ubiquitous in the natural environment and can significantly influence the environmental behavior of pollutants. This work examined the mediating effects of graphite, soot, and biochar on 1-naphthylamine (1-NA) oxidation under aerobic conditions. It was shown that the three BCs significantly promoted the oxidation of 1-NA in the dark, and the mediation efficiency of graphite was much greater than that of soot or biochar. The oxidation products were the coupling oligomers (dimers and trimers) and the oxygen-containing oligomers of 1-NA (di-OH-1-NA, OH-azo naphthalene, OH-trimers and amino-naphthoquinone derivatives etc.). The phenolic -OH on BCs were identified as the active sites for 1-NA oxidation, which could stimulate O2 to produce reactive oxygen species through successive single electron transfer and then cause 1-NA oxidation. Moreover, the superior catalytic performance of graphite was also related to its high electrical conductivity. The synergies between the sp²-hybridized carbon surface and the active sites (such as phenolic -OH and defects) facilitated the oxidation of 1-NA on graphite. Findings in this study not only are helpful for better understanding the reactivity of environmental BCs, but also provide new insights into the risk assessment of 1-NA in the natural environment.
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Pyrogenic Carbonaceous Matter (PCM; e.g., black carbon, biochar, and activated carbon) are solid residues from incomplete combustion of fossil fuel or biomass. They are traditionally viewed as inert adsorbents for sequestering contaminants from the aqueous phase or providing surfaces for microbes to grow. In this account, we reviewed the recently discovered reactivity of PCM in promoting both chemical and microbial synergies that are important in pollutant transformation, biogeochemical processes of redox-active elements, and climate change mitigation with respect to the interaction between biochar and nitrous oxide (N2O). Moreover, we focused on our group’s work in the PCM-enhanced abiotic transformation of nitrogenous and halogenated pollutants and conducted in-depth analysis of the reaction pathways. To understand what properties of PCM confer its reactivity, our group pioneered the use of PCM-like polymers, namely conjugated microporous polymers (CMPs), to mimic the performance of PCM. This approach allows for the controlled incorporation of specific surface properties (e.g., quinones) into the polymer network during the polymer synthesis. As a result, the relationship between specific characteristics of PCM and its reactivity in facilitating the decay of a model pollutant was systematically studied in our group’s work. The findings summarized in this account help us to better understand an overlooked environmental process where PCM synergistically interacts with various environmental reagents such as hydrogen sulfide and water. Moreover, the knowledge gained in these studies could inform the design of a new generation of reactive carbonaceous materials with tailored properties that are highly efficient in contaminant removal.
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Large amounts of glomalin-related soil protein (GRSP) are present in the soil; however, the impacts of GRSP on the chemical process of soil polycyclic aromatic hydrocarbons (PAHs) are far under investigation. This research sought to elucidate the sorption of phenanthrene as a representative PAH by soils, including Kandiudult, TypicPaleudalf, and Mollisols with co-existing GRSP (0-50 mg/L). The results indicated that soil sorption capacities for phenanthrene reduced significantly. Notably, GRSP changed the sorption process of phenanthrene by Kandiudult, well described as the Freundlich model. In contrast, the phenanthrene sorption isotherms were well described with the Linear model for TypicPaleudalf and Mollisols. The reduced percentage of phenanthrene sorption due to GRSP addition was 7.01%-49.21%, 23.92%-68.71%, and17.26%-66.80% for Kandiudult, TypicPaleudalf and Mollisols, respectively. It was noted that GRSP has a strong capacity for phenanthrene sorption in aqueous solutions and elevates the availability of phenanthrene for microorganisms or plants. During the sorption process, the introduction of GRSP resulted in the reduction of organic matter in soils and elevated the concentrations of dissolved organic matter in solutions, which was the primary mechanism of GRSP-reduced phenanthrene sorption by soils. The findings revealed that GRSP enrichment can increase the mobility of PAHs in contaminated soils.
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Equilibrium passive sampling methods (EPSM) allow quantification of freely dissolved contaminant concentrations (Cfree) in sediment porewater. Polydimethylsiloxane (PDMS) is a convenient sampling polymer that can be equilibrated in field (in‐situ) or laboratory sediments (ex‐situ) to determine Cfree providing reliable compound‐specific PDMS‐water partition coefficients (KPDMS‐water) are available. Polycyclic aromatic hydrocarbons (PAHs) are an important class of sediment contaminants comprised of parent and alkylated homologs. However, application of EPSM to alkylated PAHs is challenged by lack of KPDMS‐water measurements. Our first objective was to obtain KPDMS‐water for nine alkylated PAHs and biphenyl using three different PDMS coated fibers. Quantitative relationships were then established to define KPDMS‐water for 18 parent and 16 alkyl PAHs included in USEPA's sediment quality benchmark method for benthic life protection based on additive toxic units (∑TUs). The second objective was to compare Cfree in porewater obtained using both in‐situ and ex‐situ EPSM at six Baltic Sea locations. Results indicated that in‐situ and ex‐situ Cfree for alkyl PAHs generally agreed within a factor of three. Further, all sites exhibited ∑TUs < 1 indicating PAHs pose a low risk to benthos. Results extend practical application of EPSM for improved risk assessment and derivation of porewater‐based remediation goals for PAH contaminated sediments. This article is protected by copyright. All rights reserved.
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The stable and radioactive isotopes (δ¹³C, Δ¹⁴C and δ²H) of black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) in the sediment from the western coastal areas of the Yellow Sea (i.e. the Jiangsu coastal areas (JCA)) were examined to identify the sources these environmental pollutants in the JCA. The results presented that the spatial heterogeneous characteristics of BC and PAHs were markedly presented in the JCA. This was suggestive of presence of the contributions of multiple potential environmental pollution sources. This can be solved and decoupled by applying the Bayesian mode. Accordingly, the statistical model showed that the major environmental pollution contributions is considered as coal combustion (39%) in the JCA. The liquid fossil fuels, petrogenic sources, and biomass combustion were accounted for 27%, 19%, and 15% in the JCA, respectively. The stable and radioactive carbon isotopic ratios (δ¹³C and Δ¹⁴C) of BC collected from the JCA are also applied to discriminate quantitatively the source of contamination. It is demonstrated that the BC in this study originates mainly from combustion of fossil fuels. And rock-derived BC as well as C3 and C4 plants combustions are also numerically predominant for BC and PAHs pollution in the coastal area. It is implied that the environmental PAHs and BC in the JCA seem to origin relatively homologies sources. Furthermore, it is suggested that the stable and radioactive carbon isotopes as well as hydrogen isotopes may be powerful and useful method to source apportionment, and have much advantages to clarify quantitatively BC and PAH pollutions in the coastal environment, but also detailed insights into the source apportionment and fate of the organic carbon in the marginal sea.
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Plant nutrition nanotechnology's implementation encourages the production of slow/controlled release fertilizers that increase fertilizer performance and reduce nutrient losses to the environment, making them environmentally friendly. The effectiveness of conventional nitrogen for fertilizers is 30–60%, whereas 80–90% of traditional phosphate fertilizers is lost by chemical bonding in the soil and is not accessible to plants. Nanosensors have many advantages for pesticide residue detection, such as lightweight designs, sensitivity, low detection range, super selectivity, and rapid response. To verify pesticides' existence, enzyme biosensors are based on the enzyme inhibition computation used in the enzymatic reaction. Optical biosensors use multiple sensor methods to analyse biomolecular interactions, such as resonant mirrors, surface plasmon resonance (SPR), and waveguides. The environmental risk assessment of NPS remains subject to various problems, including chemical characterization of test products, reference nanomaterials for toxicity control, improvements in test methodology, additional measurements within the existing experiments, and quantification of novel or unusual toxicological characteristics. Challenges exist in categorizing nanoparticles (NPs) about their impact on life cycles and deciding their entry points into the environment.
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Urban horticulture (UH) has been proposed as a solution to increase urban sustainability, but the potential risks to human health due to potentially elevated soil heavy metals and metalloids (HM) concentrations represent a major constraint for UH expansion. Here we provide the first UK-wide assessment of soil HM concentrations (total and bioavailable) in UH soils and the factors influencing their bioavailability to crops. Soils from 200 allotments across ten cities in the UK were collected and analysed for HM concentrations, black carbon (BC) and organic carbon (OC) concentrations, pH and texture. We found that although HM are widespread across UK UH soils, most concentrations fell below the respective UK soil screening values (C4SLs): 99 % Cr; 98 % As, Cd, Ni; 95 % Cu; 52 % Zn. However, 83 % of Pb concentrations exceeded C4SL, but only 3.5 % were above Pb national background concentration of 820 mg kg⁻¹. The bioavailable HM concentrations represent a small fraction (0.01–1.8 %) of the total concentrations even for those soils that exceeded C4SLs. There was a significant positive relationship between both total and bioavailable HM and soil BC and OC concentrations. This suggest that while contributing to the accumulation of HM concentrations in UH soils, BC and OC may also provide a biding surface for the bioavailable HM concentrations contributing to their immobilisation. These findings have implications for both management of the risk to human health associated with UH growing in urban soils and with management of UH soil. There is a clear need to understand the mechanisms driving soil-to-crop HM transfer in UH to improve potentially restrictive C4SL (e.g. Pb) especially as public demand for UH land is growing. In addition, the UH community would benefit from education programs promoting soil management practices that reduce the risk of HM exposure - particularly in those plots where C4SLs were exceeded.
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After decades of imposed regulations about reducing the primary emissions of persistent organic pollutants (POPs), these pollutants are still present in the environment. Soils are important repositories of such persistent semivolatile organic contaminants (SVOCs), and it is assumed that SVOCs sequestered in these reservoirs are being re-mobilized due to anthropogenic influence. In this study, concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in soil and air, their fugacities, fluxes and the soil-air partition coefficient (KSA) were determined for three different land cover types (glacial, remote/mountainous and urban) of the Lesser Himalayan Region (LHR). The concentrations of OCPs, PCBs and PBDEs in soils and air ranged between 0.01 and 2.8, 0.81–4.8, 0.089–0.75 ng g⁻¹; 0.2–106, 0.027–182, and 0.011–7.26 pg m⁻³, respectively. The levels of SVOCs in the soil were correlated with soil organic matter (SOM) indicating that SOM is a substrate for the organic pollutants in soils. The Clausius-Clapeyron plots between ln P and inverse of temperature (1000/T) suggested that long range atmospheric transport was the major input source of PBDEs and higher chlorinated PCBs over the LHR. The uneven and wide distribution of local sources in LHR and up-slope enrichment of SVOCs explained the spatial variability and altitudinal patterns. The soils near mountain and urban lakes act as local sinks of SVOCs such as β-HCH, pp΄-DDT, CB-28, -118, −153, BDE-47, -99, and −154, with soil-air exchange fluxes tending more toward deposition. However, the soils near glacial lakes acted as local sources of more volatile congeners of α-HCH, γ-HCH, op′-DDT, pp′-DDE and lower to medium chlorinated PCBs such as CB-18, -28, −53, −42 and BDE-47, -99, with soil-air exchange tending more toward volatilization flux.
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During the last few decades, black carbon (BC) has attracted significant attention among scientific communities due to its observable hostile effects on air quality, agriculture, forests, human health, the economy, and environment. BC is a light-absorbing particle in the atmosphere that is emitted mainly from fossil fuels, biomass burning, and vehicular emissions. Although ample studies on BC aerosol characteristics have been carried out worldwide, significant uncertainties remain due to the different emission sources and their interactions with complex atmospheric processes. Thus, an in-depth understanding of BC and its potential impacts is greatly needed. This chapter presents a brief overview of the characteristics, sources, and transport mechanisms of BC and its impacts on the environment as well as human health. In addition, the chapter also highlights instructions to the public, policymakers, and local environmental bodies to control BC emissions.
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Black carbon (BC) is a significant driver of global climate change, and its long‐term variation is affected by a combination of anthropogenic activities and meteorological diffusion conditions. However, distinguishing the effects of these two factors on BC variation has proven difficult. In this study, we used the China Black Carbon Observational Network data set to assess the diurnal, seasonal, and long‐term BC trends at Mt. Waliguan (WLG) from 2008 to 2017. The mean BC concentration at WLG was 449 ± 366 ng/m³, with a decreasing trend of 2 %yr⁻¹, which was mainly related to emission reduction measures in China. The BC concentration at WLG was higher under easterly air masses than that under westerly air masses, which suggests that the former are conducive to BC transport from the highly polluted eastern regions. Due to the origin and velocity of air masses, the BC concentration at WLG in summer is higher than that in winter. The intensity of the Tibetan Plateau monsoon had an important positive influence on the easterly air masses frequency, which modulated BC transport to WLG in summer. According to the concentration‐weighted trajectory analysis, the high‐potential BC source regions were distributed in Lanzhou, Chengdu, and Xi'an urban agglomerations as well as in northern India. Community Atmosphere Model 5 simulations with a BC‐tagging technique inferred North Central China, Northwest China, and Indian Peninsula to be the major BC source regions to WLG, accounting for 56.1%, 17.5%, and 12.1% of the total BC, respectively.
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Remediation of hydrophobic organic contaminants using activated carbon is an effective means by which to clean up contaminated areas. Predicting remediation success using laboratory experimentation with soil, however, is unclear. Current remediation efforts involving activated carbon addition to floodplain soils downstream of the Velsicol Chemical Corporation Superfund Site (VCCSS) have offered the opportunity to directly compare in situ activated carbon remediation with laboratory experimentation. The objective of the current study was to compare bioaccumulation of DDT, DDD, and DDE (DDX) residues by earthworms (Eisenia fetida) exposed to laboratory-aged (LA) or field-aged (FA) soils from four locations. Samples were evaluated at 0-, 3-, and 9-months post-remediation to determine the ability of laboratory studies to predict in situ remediation. Floodplain soils downstream from the VCCSS were amended with 2% by weight activated carbon in the field and the laboratory, and then aged for 3- or 9-months. At 0-, 3-, and 9-months bioaccumulation assays were conducted with LA and FA soils and tissue concentrations were compared within study sites. In both LA and FA soils, activated carbon caused significant reductions (37.01–92.94%) in bioaccumulated DDX in earthworms. Field-collected worms showed a similar trend in reduction of bioaccumulated DDX, suggesting activated carbon remediation was successful in reducing bioavailable DDX for native organisms within the floodplain soils. The rate of reduction in bioavailable DDX, however, was significantly faster in LA soils (β = −0.189, p < 0.0001) compared to FA soils (β = −0.054, p < 0.0038). Differences in temperature and methods of activated carbon incorporation between LA and FA soils may account for the differences in remediation rate, suggesting laboratory experiments may overpredict the extent or speed in which remediation occurs in the field. Therefore, use of laboratory studies in predicting success of activated carbon remediation may be most effective when conditions mimic field remediation as closely as possible.
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With improved analytical techniques, environmental monitoring studies are increasingly able to report the occurrence of tens or hundreds of chemicals per site, making it difficult to identify the most relevant chemicals from a biological standpoint. For this study, organic chemical occurrence was examined, individually and as mixtures, in the context of potential biological effects. Sediment was collected at 71 Great Lakes tributary sites and analyzed for 87 chemicals. Multiple risk‐based lines of evidence were used to prioritize chemicals and locations, including comparing sediment concentrations and estimated porewater concentrations to established whole‐organism benchmarks (i.e., sediment and water quality criteria and screening values) and to high‐throughput toxicity screening data from the U.S. Environmental Protection Agency's ToxCast database, estimating additive effects of chemical mixtures on common ToxCast endpoints, and estimating toxic equivalencies for mixtures of alkylphenols and polycyclic aromatic hydrocarbons (PAHs). This multiple‐lines‐of‐evidence approach enabled the screening of more chemicals, mitigated the uncertainties of individual approaches, and strengthened common conclusions. Collectively, at least one benchmark/screening value was exceeded for 54 of the 87 chemicals, with exceedances observed at all 71 of the monitoring sites. Chemicals with the greatest potential for biological effects, both individually and as mixture components, were bisphenol A, 4‐nonylphenol, indole, carbazole, and several polycyclic aromatic hydrocarbons (PAHs). Potential adverse outcomes based on ToxCast gene targets and putative adverse outcome pathways relevant to individual chemicals and chemical mixtures included tumors, skewed sex ratios, reproductive dysfunction, hepatic steatosis, and early mortality, among others. Results provide a screening level prioritization of chemicals with the greatest potential for adverse biological effects and an indication of sites where they are most likely to occur. This article is protected by copyright. All rights reserved.
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Plastic contamination is ubiquitous in the environment and has been related to increasing global plastic usage since the 1950s. Considering the omnipresence of additives in plastics, the risk posed by this contamination is related not only to the physical effects of plastic particles but also to their additive content. Until now, most routine environmental monitoring programs involving additives have not considered the presence of these additives still associated with the plastic they were added to during their production. Understanding environmental additive speciation is essential to address the risk they pose through their bioavailability and plastic-associated transport. Here, we present and apply a theoretical framework for sampling and analytical procedures to characterize the speciation of hydrophobic nonionized additives in environmental compartments. We show that this simple framework can help develop sampling and sample treatment procedures to quantify plastic-associated additives and understand additive distribution between plastics and organic matter. When applied to concrete cases, internal consistency checks with the model allowed for identifying plastic-associated additives in a sample. In other cases, the plastic-organic carbon ratio and additive concentration in the matrix are key factors affecting the ability to identify plastic-associated additives. The effect of additive dissipation through diffusion out of plastic particles is also considered.
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Single-point Tenax extractions are a viable means of estimating bioaccessibility of hydrophobic organic contaminants in sediment, soil, and intestinal fluids. One advantage of this extraction technique is that after thorough cleaning and drying, Tenax beads can be reused in subsequent extractions with the assumption that no changes in bioaccessibility estimates will occur. This assumption of reusability, however, has not been tested. Therefore, the objective of the current study was to evaluate the reusability of Tenax beads by comparing bioaccessible polychlorinated biphenyl (PCB) concentrations measured by differently aged Tenax beads. New Tenax beads (60–80 mesh) were aged through 24 h single-point Tenax extractions of clean sand 0, 1, 5, 10, 15, 20, and 25 times. The aged Tenax was then used to extract 27 PCB congeners from laboratory spiked sediment and the bioaccessible PCB concentrations were compared. Despite significant effects of PCB congener (F26, 567 = 97.291, p = 2.00 × 10⁻¹⁶), Tenax age (F6, 567 = 14.735, p = 1.12 × 10⁻¹⁵), and the interaction of these two terms (F156, 567 = 1.711, p = 4.79 × 10⁻⁶) on bioaccessible concentrations measured by Tenax, the significance was due to two PCB congeners that showed large variation during analytical quantification. For the remaining 25 congeners, no differences in bioaccessible PCB concentrations were found between differently aged Tenax, suggesting repeated use did not impact bioaccessible estimates provided by Tenax. Scanning electron microscope imaging revealed no significant changes in the visible surface area of the Tenax beads after aging (F6, 203 = 1.434, p = 0.203), suggesting no significant changes in the Tenax phase volume resulting in consistent estimates of bioaccessibility through repeated use. Given the strong correlations between single-point Tenax extractable and tissue concentrations, providing data to detail the reusability of Tenax in repeated extractions further demonstrates the applicability of this extraction technique in risk assessment.
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This study presents a computational investigation of geometric parameters, infrared (IR) and Raman frequencies as well as molecular Rayleigh scattering of polycyclic aromatic hydrocarbons (PAHs), used as models for subunits...
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Carbonaceous fractions throughout the normal period and lockdown period (LP) before and during COVID-19 outbreak were analyzed in a polluted city, Zhengzhou, China. During LP, fine particulate matters, elemental carbon (EC), and secondary organic aerosol (SOC) concentrations fell significantly (29%, 32% and 21%), whereas organic carbon (OC) only decreased by 4%. Furthermore, the mean OC/EC ratio increased (from 3.8 to 5.4) and the EC fractions declined dramatically, indicating a reduction in vehicle emission contribution. The fact that OC1–3, EC, and EC1 had good correlations suggested that OC1–3 emanated from primary emissions. OC4 was partly from secondary generation, and increased correlations of OC4 with OC1–3 during LP indicated a decrease in the share of SOC. SOC was more impacted by NO2 throughout the research phase, thereby the concentrations were lower during LP when NO2 levels were lower. SOC and relative humidity (RH) were found to be positively associated only when RH was below 80% and 60% during the normal period (NP) and LP, respectively. SOC, Coal combustion, gasoline vehicles, biomass burning, diesel vehicles were identified as major sources by the Positive Matrix Factorization (PMF) model. Contribution of SOC apportioned by PMF was 3.4 and 3.0 μg/m³, comparable to the calculated findings (3.8 and 3.0 μg/m³) during the two periods. During LP, contributions from gasoline vehicles dropped the most, from 47% to 37% and from 7.1 to 4.3 μg/m³, contribution of biomass burning and diesel vehicles fell by 3% (0.6 μg/m³) and 1% (0.4 μg/m³), and coal combustion concentrations remained nearly constant. The findings of this study highlight the immense importance of anthropogenic source reduction in carbonaceous component variations and SOC generation, and provide significant insight into the temporal variations and sources of carbonaceous fractions in polluted cities.
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Black carbon (BC) is a product of incomplete combustion of fossil fuels and vegetation. The compelling evidence has demonstrated that it has a close relationship with several respiratory and cardiovascular diseases. BC provides the reactive sites and surfaces to absorb various chemicals, such as polycyclic aromatic hydrocarbons (PAH). Naphthoquinone is a typical PAHs which was found in particulate matter (PM) and 1,4NQ-BC owned high oxidative potential and cytotoxicity. IL-33 is an alarmin which increases innate immunity through Th2 responses. It was reported that IL-33 was a potent inducer of pro-inflammatory cytokines, like IL-6. In our previous study, it was revealed that 1,4NQ-BC instilled intratracheally to mice could trigger the lung inflammation and stimulate the secretion of IL-33 in lung tissue. We found that IL-33 could induce inflammation in lung itself. When the macrophages were eliminated, the secretion of IL-33 was reduced and the pathological damage in the lung was relieved after exposure to 1,4NQ-BC. Both MAPK and PI3K/AKT signal pathways were involved in the process of IL-33 secretion and the lung inflammation induced by 1,4NQ-BC. The findings herein support the notion that after exposure to 1,4NQ-BC, the increased secretion of IL-33 was mainly derived from macrophages through both MAPK and PI3K/AKT signal pathways.
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This review highlights the ubiquity of black carbon (BC) produced by incomplete combustion of plant material and fossil fuels in peats, soils, and lacustrine and marine sediments. We examine various definitions and analytical approaches and seek to provide a common language. BC represents a continuum from partly charred material to graphite and soot particles, with no general agreement on clear-cut boundaries. Formation of BC can occur in two fundamentally different ways. Volatiles recondense to highly graphitized soot-BC, whereas the solid residues form char-BC. Both forms of BC are relatively inert and are distributed globally by water and wind via fluvial and atmospheric transport. We summarize, chronologically, the ubiquity of BC in soils and sediments since Devonian times, differentiating between BC from vegetation fires and from fossil fuel combustion. BC has important implications for various biological, geochemical and environmental processes. As examples, BC may represent a significant sink in the global carbon cycle, affect the Earth's radiative heat balance, be a useful tracer for Earth's fire history, build up a significant fraction of carbon buried in soils and sediments, and carry organic pollutants. On land, BC seems to be abundant in dark-colored soils, affected by frequent vegetation burning and fossil fuel combustion, thus probably contributing to the highly stable aromatic components of soil organic matter. We discuss challenges for future research. Despite the great importance of BC, only limited progress has been made in calibrating analytical techniques. Progress in the quantification of BC is likely to come from systematic intercomparison using BCs from different sources and in different natural matrices. BC identification could benefit from isotopic and spectroscopic techniques applied at the bulk and molecular levels. The key to estimating BC stocks in soils and sediments is an understanding of the processes involved in BC degradation on a molecular level. A promising approach would be the combination of short-term laboratory experiments and long-term field trials.
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Typical polycyclic aromatic hydrocarbon mixtures are established lung carcinogens, but the quantitative exposure-response relationship is less clear. To clarify this relationship we conducted a review and meta-analysis of published reports of occupational epidemiologic studies. Thirty-nine cohorts were included. The average estimated unit relative risk (URR) at 100 mug/m(3) years benzo[a]pyrene was 1.20 [95% confidence interval (CI), 1.11-1.29] and was nor sensitive to particular studies or analytic methods. However, the URR varied by industry. The estimated means in coke ovens, gasworks, and aluminum production works were similar (1.15-1.17). Average URRs in other industries were higher but imprecisely estimated, with those for asphalt (17.5; CI, 4.21-72.78) and chimney sweeps (16.2; Cl, 1.64-160.7) significantly higher than the three above. There was no statistically significant variation of URRs within industry or in relation to study design (including whether adjusted for smoking), or source of exposure information. Limited information on total dust exposure did not suggest that dust exposure was an important confounder or modified the effect. These results provide a more secure basis for risk assessment than was previously available.
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Historical records of the concentrations of black carbon (BC) and elemental carbon (EC), as well as of water insoluble organic carbon (OC) and total carbon (TC) covering the time period ~1755-1975 are presented. Concentrations were obtained from an ice core of a European high-alpine glacier, using an optical and a thermal method. Concentrations were found to vary between 7 and 128 mug L-1 for BC, between 5 and 130 mug L-1 for EC, between 53 and 484 mug L-1 for OC, and between 66 and 614 mug L-1 for TC. From preindustrial (1755-1890) to modern times (1950-1975) BC, EC, OC, and TC concentrations increased by a factor of 3.7, 3.0, 2.5, and 2.6, respectively. The sum of BC emissions of Germany, France, Switzerland, and Italy, calculated from fossil fuel consumption, and the EC concentration record correlate well (R2=0.56) for the time period from 1890 to 1975; this indicates that the ice core record reflects the emissions of western Europe. High pre-1860 concentrations indicate that by that time BC emissions to the atmosphere were already significant.
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Formation of highly condensed black carbon (BC) from vegetation fires and wood fuel combustion presumably transfers otherwise rapidly cycling carbon from the atmosphere-biosphere cycle into a much slower cycling geological form. Recently reported BC fractions of total organic carbon (TOC) in surficial marine sediments span a wide range (2-90%), leaving it presently unclear whether this variation reflects natural processes or is largely due to method differences. In order to elucidate the importance of BC to carbon burial the specificity of applied methods needs to be constrained. Here the operating range and applicability of a commonly used chemothermal oxidation (CTO) method is evaluated using putative BC standards, potentially interfering substances, and natural matrix standards. Test results confirm the applicability of the method to marine sediments. Integrity tests with model substrates suggest applicability to low-carbon soils but only with a lower specificity to seawater particulate matter. The BC content of marine sediment samples in a set of studies employing the CTO method proved to be consistent with associated geochemical information. The radiocarbon content of the BC isolate in an environmental matrix standard was shown to be similar to the radiocarbon signature of pyrogenic polycyclic aromatic hydrocarbons (PAHs), here serving as molecular markers of combustion (fraction modern fM of BC was 0.065+/-0.014 and of PAHs 0.056+/-0.020), while being clearly distinct from the radiocarbon content of the bulk TOC (fM=0.61+/-0.08). Urgent questions such as the global accumulation rate of black carbon in soils and sediments may prove approachable with the chemothermal oxidation technique of BC quantification.
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We measured black carbon (BC) in ultrafiltered, high-molecular weight dissolved organic matter (UDOM) in surface waters of Delaware Bay, Chesapeake Bay, and the adjacent Atlantic Ocean (U.S.A.) to investigate the importance of riverine and estuarine dissolved organic matter (DOM) as a source of BC to the ocean. BC was 5- 72% of UDOM-C (27 6 17%), which corresponds to 8.9 6 6.5% of dissolved organic carbon (DOC), with higher values in the heavily urbanized midbay region of the Delaware Estuary and lower yields in the river and coastal ocean. The spatial and seasonal distributions of BC along the salinity gradient of Delaware Bay suggest that the elevated levels of BC in surface water UDOM originate from localized sources, possibly from atmospheric depo- sition or release from resuspended sediments. BC in UDOM made up 4-7% of the DOC in the coastal Atlantic Ocean, revealing that river-estuary systems are important exporters of colloidal BC to the ocean. The annual flux of BC from Delaware Bay UDOM to the Atlantic Ocean was estimated at 2.4 3 10 10 gB C yr 21
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Bioavailability and accumulation of sediment-bound polycyclic aromatic hydrocarbons (PAHs) by benthic biota are closely related to their extractability by water or mild aqueous solvents. Nevertheless, PAH accumulation by benthic organisms is sometimes considerably different from predictions based on an equilibrium partition coefficient KOC between water and bulk sedimentary organic carbon (OC). We present evidence that PAH extractability is strongly affected by the type of OC acting as a sorbent. We compared extractability of spiked [14C]fluoranthene from a variety of natural and man-made OC matrices, including bulk sediment organic carbon, peat moss, power plant fly ash, diesel soot, petroleum/natural gas soot, coal dust and carbon black. Artificial sediments were prepared from glass beads amended with equal weight percentages (2%) of nine different types of OC. Amended sediments were spiked with [14C]fluoranthene and batch-extracted with seawater and 0.5 % sodium dodecyl sulfate (SDS) after 65 h and 12 h of equilibration, respectively. Fluoranthene extractability by seawater ranged between 0.03 - 0.9%, corresponding to a 50-fold variation of apparent KOC, and 0.03-18% for SDS. Correlation between seawater and SDS extraction efficiencies was weak, suggesting differences in the mechanism of solubilization. These results demonstrate that use of a single value of KOC to predict bioavailability of fluoranthene should be avoided, and that attempts to extrapolate PAH extractability from water-only extraction experiments to aqueous solutions containing surface-active dissolved organic carbon, such as the gut fluids of deposit feeding macrofauna, is very likely to lead to erroneous predictions.
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Remediation of groundwater contamination in unconsolidated aquifers by dissolved hydrophobic compounds (HOC) requires detailed information on the sorption parameters present in the sediments. Equilibrium sorption isotherms were measured for phenanthrene for a wide variety of lithocomponents (constituents of sand and gravel sediments) and unweathered rock fragments (limestones and sandstones). The lithocomponents were separated based on macroscopic appearance of different lithologies (e.g. limestones, sandstones, shales, mudstones, and igneous rocks) and characterized in terms of organic carbon content and specific surface area. In addition the organic matter (OM) was characterized using coal petrography methods (white and UV light microscopy). As confirmed by heat-treated samples sorption was solely due to OM. Organic carbon normalized sorption coefficients (KOC) varied by almost 3 orders of magnitude among the samples investigated. The different origin and maturity of isolated organic matter (organic facies) is believed to be responsible. For example, extremely high KOC values were found for particulate organic matter such as charcoal and coal particles which were preserved within the sandstone and limestone grains. In a second paper we report data on sorption kinetics of the samples used in this study (1).
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Biota-sediment accumulation factors (BSAFs) for some chlorinated dibenzo-p-dioxin and dibenzofuran congeners (PCDD/Fs) in Dungeness crab (Cancer magister) hepatopancreas and associated sediments are concentration independent as required by equilibrium partition models. In particular 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), 2,3,7,8-tetrachlorodibenzofuran, the 2,3,7,8-substituted pentachlorodibenzofurans, and the non-2,3,7,8-hexachlorodibenzofurans (HxCDFs) seem to fall into this group. The BSAFs for other isomers exhibit significant, nonlinear variations with sediment or crab PCDD/F concentrations. For some of these other isomers (e.g., the non-2,3,7,8 TCDDs and possibility the 2,3,7,8-substituted HxCDFs), association of a variable fraction of the total present with soot carbon may provide a satisfactory explanation for the concentration behavior. For the HxCDDs we propose that the nonlinear concentration behavior may arise from the thermodynamic properties of fluids confined in hydrophobic voids within particulate and colloidal material produced by the pulp mills. The nonlinear relationship between BSAFs and PCDD/F concentrations greatly complicates prediction of the potential for dioxin and furan bioaccumulation in crabs and the formulation of sediment quality criteria. We provide a nonlinear equation relating toxic equivalency and sediment concentrations.
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In recent years, there have been sporadic reports in the lay press of individuals stuck in chimneys primarily during burglary attempts. Most of these individuals suffered from suffocation or soot inhalation. Because of the similarities between this form of breaking and entering and Santa Claus' traditional entrance into homes on Christmas Eve, we define the 'Santa Claus Syndrome' as postural (positional) asphyxia, inhalational injuries and body bums, and/or complications related to compartment syndrome due to entrapment in chimneys. We report a case of a man who became trapped in a chimney during a burglary attempt and died a delayed death due to postural asphyxia associated with inhalational and burn injuries and anterior compartment syndrome. An analysis of this unusual case is presented. Exhaustional and postural asphyxia, compartment syndromes, and confined space-hypoxia syndrome are also discussed.
Article
The accumulation of organic chemicals in aquatic animals has been modeled at several levels of detail. In the simplest formation a partition coefficient (the bioconcentration factor) is used to define the concentration in the animal relative to the concentration in the water. A more complex formulation is the food chain model in which the kinetics of chemical uptake and loss by each level of the food chain are explicitly specified. Examples of the use of both approaches are presented. A reformulation of the food chain model to relate accumulation to the octanol-water partition coefficient (Kow) of the chemical is presented. This model is applicable to a wide range of chemicals. This paper presents the equations used to parameterize exposure, uptake and loss for aquatic food chains, reviews the previous application of the equations to specific problem contexts, and presents the application of the equations to the full range of organic chemicals as defined by Kow. -from Authors
Article
Concentrations and 210Pb-derived fluxes of Black Carbon (BC) were deduced in recent ocean margin sediments off northeastern USA to investigate the role of this carbon form in the biogeochemical cycle of this element. BC concentrations in contemporary open shelf sediments ranged between 0.11 and 1.7 mg/gdw. Temporal trends of BC in cores, as well as the pattern of chemical markers of combustion sources, were consistent with anthropogenic fossil fuel combustion dominating the BC input to these sediments in recent times. BC fluxes of 1–2 g m−2 yr−1 suggest that the northeastern USA shelf sink is of the same magnitude as estimates of the BC production from fossil fuel and biomass burning in the upwind NE USA source region. Identification of about 10% of total organic carbon as BC has implications for sedimentary carbon preservation, as well as several other aspects of the global biogeochemical cycle of carbon.
Article
Vapour pressure, aqueous solubility, Henry law constant, n-octanol- and sediment-water partition coefficient and bioconcentration factor of all chlorinated dibenzofurans (PCDF) and dibenzo-p-dioxins (PCDD), in addition to those of the parent compounds DF and DD, were calculated via the SOFA (SOlubility parameters for Fate Analysis)- model. The derivation of these 1272 values was based on 120 experimental data. Mean deviation of calculated values from experimental data amounted to 0.39, 0.25, 0.31, 0.19, 0.34 and 0.18 log units for the properties mentioned. The values of all compounds were tabulated. Variation of values within isomer groups turned out to be the highest for vapour pressure of the tetra substituted group, but were below 1.40 orders of magnitude. Variation in the complete series amounted to 7.78 orders at a maximum, again for vapour pressure. Accurate, almost linear, relationships were established between the n-octanol-water partition coefficient and aqueous solubility and sediment-water partition coefficient, whereas a parabolic relationship turned out to hold with the bioconcentration factor.
Article
The chemical interactions of hydrophobic organic contaminants (HOCs) with soils and sediments (geosorbents) may result in strong binding and slow subsequent release rates that significantly affect remediation rates and endpoints. The underlying physical and chemical phenomena potentially responsible for this apparent sequestration of HOCs by geosorbents are not well understood. This challenges our concepts for assessing exposure and toxicity and for setting environmental quality criteria. Currently there are no direct observational data revealing the molecular-scale locations in which nonpolar organic compounds accumulate when associated with natural soils or sediments. Hence macroscopic observations are used to make inferences about sorption mechanisms and the chemical factors affecting the sequestration of HOCs by geosorbents. Recent observations suggest that HOC interactions with geosorbents comprise different inorganic and organic surfaces and matrices, and distinctions may be drawn along these lines, particularly with regard to the roles of inorganic micropores, natural sorbent organic matter components, combustion residue particulate carbon, and spilled organic liquids. Certain manipulations of sorbates or sorbent media may help reveal sorption mechanisms, but mixed sorption phenomena complicate the interpretation of macroscopic data regarding diffusion of HOCs into and out of different matrices and the hysteretic sorption and aging effects commonly observed for geosorbents. Analytical characterizations at the microscale, and mechanistic models derived therefrom, are needed to advance scientific knowledge of HOC sequestration, release, and environmental risk.
Article
Gas-particle partitioning has an important influence on the fate of atmospheric polycyclic aromatic hydrocarbons (PAHs) and other semivolatile organic compounds (SOCs). In the present paper, gas- and aerosol-phase PAH concentrations and organic and elemental carbon concentrations in the aerosols measured in the Baltimore atmosphere and over the adjacent Chesapeake Bay in July 1997 were used to assess the mechanisms driving gas-particle partitioning of PAHs. The relative importance of adsorption onto the soot carbon and absorption into aerosol organic matter is evaluated by means of estimated soot/air (KSA) and octanol/air (KOA) partition coefficients, respectively. The results show that absorption into organic carbon may account for less than 10% of the total PAHs in the particulate phase. Adsorption onto the soot phase predicts accurately the total suspended particulate matter normalized partition coefficients (KP) for PAHs. For example, KSA predicts KP values for phenanthrene over the Chesapeake Bay wit...
Article
Ashtabula Harbor, Ohio is designated as a Great Lakes Area of Concern contaminated by PCBs. Information on the bioaccumulation of PCBs from sediments is important for sediment management strategies such as dredging to restore navigable depths in the harbor. To ascertain the bioaccumulation of these PCBs, the aquatic earthworm Lumbriculus variegatus was exposed in the laboratory to contaminated sediments collected from 15 areas in the harbor. Data from these bioaccumulation experiments were used to determine the bioaccumulation potential of PCBs through the calculation of Biota- Sediment Accumulation Factors (BSAFs). The results showed that the mean values of the experimentally derived BSAFs for individual harbor areas ranged from 0.27 to 1.69. The median BSAF for sediments in the lower river sector of the harbor (0.38) was significantly lower than that for upper river sediments (1.34), indicating that the high adsorptive properties of coal soot particles constrained PCB bioavailability in the lower river sediments. These results indicate that the origin of total organic carbon (TOC) has a major influence on the bioavailability of total PCBs in harbor sediments. Moreover, the empirical BSAFs were well below the 4.0 default BSAF value recommended in joint USEPA/USACE protocols that are used to evaluate the Theoretical Bioaccumulation Potential, or bioavailability, of neutral organic chemicals in Great Lakes sediments. These empirical values should be used to more precisely predict the bioavailability of total PCBs in Ashtabula Harbor sediments.
Article
A model of the BSAF is constructed for PAHs using a steady-state representation of a benthic food web of a small creek. Analyses of the data collected by others on sediment, crayfish and sunfish PAH indicate that for the crayfish, the BSAF (kg org C kg lipid{sup {minus}1}) range over log K{sub ow} is relatively narrow between 0.01 and 0.1. For the sunfish, a marked decline occurs in the station average BSAF with increasing log K{sub ow} to values ranging from 0.00001 to 0.005. A separation also occurs in the behavior of the PAH groups, with the unsubstituted PAHs constituting an approximately lower bound on the entire set of PAHs. Model calibration to crayfish and sunfish BSAF is accomplished through assignment of PAH (K{sub ow}) functions derived from laboratory data. The substituted naphthalenes in contrast to the unsubstituted PAHs are calculated to behave similarly to PCBs but lower by about one order of magnitude. Analyses of the model calibration indicate that (1) relative to the sunfish, the crayfish appear to exhibit reduced metabolism and higher gut assimilation efficiencies resulting in BSAFs different from sunfish BSAFs; (2) for the sunfish, the BSAF for unsubstituted PAHs declines rapidly with increasing K{sub ow} primarily because of low gut assimilation efficiency and increased metabolism and not because of reduced bioavailability of sediment PAH; and (3) the relative contribution of the food route and water route to the BSAF varies with K{sub ow}.
Article
A RECORD of prehistoric and historic burning of carbonaceous materials may be found in the elemental carbon contents of the sedimentary columns. The widespread dissemination of such carbon as microcrystalline graphite is indicated by its presence in atmospheric dusts collected over the North Atlantic1 and in ice nuclei collected from North Pacific airs2. Its submarine survival over geologic time periods, at least up to millions of years, is suggested by its occurrence in manganese nodules3 and in sediments from the Sierra Leone Rise1. But a biologically mediated oxidation of elemental carbon in terrestrial soils has been proposed to explain the gradual disappearance of charcoals originating from forest fires4. The contributions of carbon from industrial activities are also visible and well documented (see, for example, ref. 5).
Article
We have determined the black carbon concentration in Greenland Dye-3 ice core samples covering the time period from about 3380 to 100 years before present. The average concentration found is 1.53 μg of black carbon per 1kg of ice. We have found significantly lower black carbon concentrations during the time period from 750 to 100 years before present connected possibly with the Little Ice Age and corresponding changes in atmospheric general circulation patterns and black carbon sources. -Authors
Article
Concentrations of di, and trichlorobenzenes were determined in porewater and sediment of a sediment core from lake Keterlmeer, the Netherlands. Average in-situ partition conefficients for di, and trichlorobenzene. Concentrations of di- and trichlorobenzenes in porewater were 1 to 2 orders of magnitude lower than calculated from the sediment data using literature partition coefficients. In-situ partition coefficients differed from literature values for partition coefficients obtained in lab experiments by a factor of 8 to 160. Assuming that the low concentrations in porewater canbe attributed to the presence of a slow desorbing fraction it can be calculated that for most compounds studied more than 95% of the measured sediment concentrations was present in the slow desorbing fraction.
Article
This review highlights the ubiquity of black carbon (BC) produced by incomplete combustion of plant material and fossil fuels in peats, soils, and lacustrine and marine sediments. We examine various definitions and analytical approaches and seek to provide a common language. BC represents a continuum from partly charred material to graphite and soot particles, with no general agreement on clear-cut boundaries. Formation of BC can occur in two fundamentally different ways. Volatiles recondense to highly graphitized soot-BC, whereas the solid residues form char-BC. Both forms of BC are relatively inert and are distributed globally by water and wind via fluvial and atmospheric transport. We summarize, chronologically, the ubiquity of BC in soils and sediments since Devonian times, differentiating between BC from vegetation fires and from fossil fuel combustion. BC has important implications for various biological, geochemical and environmental processes. As examples, BC may represent a significant sink in the global carbon cycle, affect the Earth's radiative heat balance, be a useful tracer for Earth's fire history, build up a significant fraction of carbon buried in soils and sediments, and carry organic pollutants. On land, BC seems to be abundant in dark-colored soils, affected by frequent vegetation burning and fossil fuel combustion, thus probably contributing to the highly stable aromatic components of soil organic matter. We discuss challenges for future research. Despite the great importance of BC, only limited progress has been made in calibrating analytical techniques. Progress in the quantification of BC is likely to come from systematic intercomparison using BCs from different sources and in different natural matrices. BC identification could benefit from isotopic and spectroscopic techniques applied at the bulk and molecular levels. The key to estimating BC stocks in soils and sediments is an understanding of the processes involved in BC degradation on a molecular level. A promising approach would be the combination of short-term laboratory experiments and long-term field trials.
Article
A dual reactive domain model (DRDM) for sorption of hydrophobic organic contaminants by soils, sediments, and other geosorbents is described. The model is predicated on the hypothesis that heterogeneous natural sorbent organic matter (SOM) comprises two principal chemostructurally different domains; a highly amorphous domain and a relatively condensed domain. The existence of two chemically and phenomenologically different SOM domains is evidenced by observations of a glass transition for a soil-derived humic acid. Extensive examinations of phenanthrene sorption and desorption for a broad range of soils, sediments, shales, and kerogens reveal that sorption by condensed SOM matrices is nonlinear and hysteretic while sorption by amorphous SOM domains is linear and completely reversible. Semi-quantitative correlations between SOM oxygen/carbon (O/C) atomic ratios and isotherm linearity (n), single-point KOC values, and degrees of sorption–desorption hysteresis indicate that the geochemistry of SOM determines binding and sequestration of organic contaminants by soils and sediments. The model reconciles observations of, and provides predictability for, various complex sorption phenomena associated with soils and sediments
Article
The distribution of aromatic contaminants between environmental solids and water solution reflects both absorption by the organic matrix (organic carbon, OC) and adsorption to black carbon (BC). In many instances, adsorption to BC dominates the interaction between aromatic contaminants and environmental solids. This holds especially true for the pyrogenically produced PAHs and PCDD/Fs, but also for the industrially produced PCBs and PCNs. In the future, research will need to surface-normalize the adsorption onto BC surfaces. One of the key questions to be addressed is the relative distribution and availability of contaminants associated with OC and BC fractions in environmental solids.
Book
Black carbon is derived largely from the incomplete combustion of fossil fuels, wood, and biomass, as well as from certain industrial processes such as the production of carbon black for automobile tires and printing inks. This book contains detailed descriptions of the physical and chemical properties of atmospheric black carbon - the soot, charcoal, and other particulate forms of impure carbon in the atmosphere - its contribution to air pollution in urban and nonurban settings, and its possible effects on climate.
Article
Three radiative-convective climate models are used to investigate the temperature changes caused by the presence of aerosol. One uses meridional heat transport (obtained from another model) and heat storage, in addition to solar and infrared radiation, to simulate the climatic effect of aerosols at selected latitude belts on a monthly, time-marching basis. A second neglects heat storage and calculates an annually averaged steady-state temperature distribution at a particular latitude belt. The third is the usual globally averaged radiative-convective model, which employs radiation as the only energy source/sink. A highly modified form of the adding radiative-transfer scheme, which splits incoming beams into either direct or diffuse streams, is used to calculate aerosol effects in solar wavelengths. The present atmospheric aerosol induces roughly comparable cooling in all three models.
Article
Gas-particle partitioning has an important influence on the fate of atmospheric polycyclic aromatic hydrocarbons (PAHs) and other semivolatile organic compounds (SOCs). In the present paper, gas- and aerosol-phase PAH concentrations and organic and elemental carbon concentrations in the aerosols measured in the Baltimore atmosphere and over the adjacent Chesapeake Bay in July 1997 were used to assess the mechanisms driving gas-particle partitioning of PAHs. The relative importance of adsorption onto the soot carbon and absorption into aerosol organic matter is evaluated by means of estimated soot/air (KSA) and octanol/air (KOA) partition coefficients, respectively. The results show that absorption into organic carbon may account for less than 10% of the total PAHs in the particulate phase. Adsorption onto the soot phase predicts accurately the total suspended particulate matter normalized partition coefficients (KP) for PAHs. For example, KSA predicts KP values for phenanthrene over the Chesapeake Bay within a factor of 3. KP predictions at the Baltimore atmosphere are within a factor of 5 to 10 of measured KP values. This is consistent with a lack of equilibrium between the gas and aerosol soot phase.
Article
Complementary mass spectrometric and spectroscopic techniques were employed to provide direct information at the microscale on the sequestration of polycyclic aromatic hydrocarbon (PAH) contaminants in Milwaukee Harbor sediment particles. Microprobe two-step laser desorption/laser ionization mass spectrometry was used for PAH measurements, infrared microspectroscopy was used for organic carbon measurement, and scanning electron microscopy with wavelength dispersive X-ray spectroscopy was used for elemental microanalysis. PAH concentrations on coal- and wood-derived particles were found to be several orders of magnitude higher than on silica particles. A cryomicrotome sectioning procedure was employed for particle cross-sectional investigations, and it was found that most PAHs are concentrated on external surface regions indicating near surface sorption mechanisms. The coal/wood-derived particles constitute only 5% of the sediment by weight but contain 62% of the total PAHs. The remaining 38% are mainly in a clay and silt fraction. PAH desorption kinetic studies on these separated fractions revealed a relatively low availability of PAHs from the coal/wood fractions and a high availability from the clay/silt fraction. Additionally, these PAH-bearing coal/wood-derived particles may be removed by density separation from heavier clay, silt, and sand.
Article
The sorption isotherms of ethylene dibromide (EDB), diuron (DUN), and 3,5-dichlorophenol (DCP) from water on the humic acid and humin fractions of a peat soil and on the humic-acid of a muck soil have been measured. The data were compared with those of the solutes with the whole peat from which the humic-acid (HA) and humin (HM) fractions were derived and on which the sorption of the solutes exhibited varying extents of nonlinear capacities at low relative concentrations (Ce/Sw). The HA fraction as prepared by the density-fractionated method is relatively pure and presumably free of high-surface-area carbonaceous material (HSACM) that is considered to be responsible for the observed nonlinear sorption for nonpolar solutes (e.g., EDB) on the peat; conversely, the base-insoluble HM fraction as prepared is presumed to be enriched with HSACM, as manifested by the greatly higher BET-(N2) surface area than that of the whole peat. The sorption of EDB on HA exhibits no visible nonlinear effect, whereas the sorption on HM shows an enhanced nonlinearity over that on the whole peat. The sorption of polar DUN and DCP on HA and HM display nonlinear effects comparable with those on the whole peat; the effects are much more significant than those with nonpolar EDB. These results conform to the hypothesis that adsorption onto a small amount of strongly adsorbing HSACM is largely responsible for the nonlinear sorption of nonpolar solutes on soils and that additional specific interactions with the active groups of soil organic matter are responsible for the generally higher nonlinear sorption of the polar solutes.
Article
Sediment organic matter heterogeneity in sediments is shown to impact the sorption behavior of contaminants. We investigated the sorptive properties as well as the composition of organic matter in different subsamples (mainly grain size fractions) of the Canadian River Alluvium (CRA). Organic petrography was used as a new tool to describe and characterize the organic matter in the subsamples. The samples studied contained many different types of organic matter including bituminous coal particles. Differences in sorption behavior were explained based on these various types of organic matter. Subsamples containing predominately coaly, particulate organic matter showed the highest Koc, the highest nonlinearity of sorption isotherms and the slowest sorption kinetics. Soil subsamples with organic matter present as organic coatings around the quartz grains evidenced the lowest Koc, the most linear sorption isotherms and the fastest sorption kinetics, which was not limited by slow intraparticle diffusion. Due to the high sorption capacity of the coaly particles even when it is present as only a small fraction of the composite organic content (<3%) causes Koc values which are much higher than expected for soil organic matter (e.g. Koc − Kow relationships). The results show that the identification and quantification of the coaly particles within a sediment or soil sample is a prerequisite in order to understand or predict sorption behavior of organic pollutants.
Article
The speciation of polycyclic aromatic hydrocarbons (PAHs) in natural waters affects both the chemical fate and the bioavailability of these compounds. PAHs may be dis solved or sorbed to particles or dissolved organic carbon (DOC). Furthermore, soot carbon has recently been shown to control the sorption of PAHs onto particles in natural waters. The present study investigated the distribution of individual PAHs among these three phases by examining the effluent and recipient waters of a Søderberg aluminum plant and evaluating the importance of soot carbon partitioning. The results showed that soot carbon may control partitioning between the dissolved and particulate phases and that the partition coefficients were orders of magnitude higher than would be expected on the basis of organic carbon−water partitioning alone. The carbon-normalized partition coefficient for the distribution of individual PAHs between DOC and the dissolved phase (KDOC) exhibited no more than a weak correlation with hydrophobicity (Kow) as compared with what was found for the partition coefficients for particles. This indicates that there are different sorption mechanisms at work with DOC than with particulate organic carbon and soot. In the recipient water, up to 90% of the total concentration of individual PAHs was accounted for by a nonfilterable DOC-associated phase, which was not retained by the polyurethane foam (PUF) adsorbent.
Article
A series of single-solute and binary-solute sorption data have been obtained on representative samples of polar compounds (substituted ureas and phenolic compounds) and of nonpolar compounds (e.g., EDB and TCE) on a peat soil and a mineral (Woodburn) soil; the data extend to low relative solute concentrations (Ce/Sw). At relatively low Ce/Sw, both the nonpolar and the polar solutes exhibit nonlinear sorption. The sorption nonlinearity approaches apparent saturation at about Ce/Sw = 0.010−0.015 for the nonpolar solutes and at about Ce/Sw = 0.10−0.13 for the polar solutes; above these Ce/Sw regions, the isotherms are practically linear. The nonlinear sorption capacities are greater for polar solutes than for nonpolar solutes and the peat soil shows a greater effect than the Woodburn soil. The small nonlinear sorption capacity for a nonpolar solute is suppressed indiscriminately by either a nonpolar or a polar cosolute at relatively low Ce/Sw of the cosolute. By contrast, the abilities of different c