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Wildfire-altered soil may be an important source of polycyclic aromatic hydrocarbons (PAHs) in the environment. With projected increase of wildfire frequency and intensity due to changing global climate, understanding the quantity and speciation of PAHs, including halogenated PAHs (XPAHs), resulting from different burn intensities has important ramifications for environmental quality concerns and global soil carbon dynamics. Here, we quantified levels of 16 U.S. Environmental Protection Agency regulated PAHs, 3 chlorinated PAHs, and 6 brominated PAHs in nonburned forest soils and burned ash/soil samples covered with black ash (B-Ash; moderate burn intensity) or white ash (W-Ash; severe burn intensity) from the 2013 Rim Fire (1,041 km 2 ) in California. The - 16 PAH concentrations follow (mean ± standard deviation; μg/kg) B-Ash (893 ± 285) > W-Ash (515 ± 333) ≈ nonburned soils (247 ± 58). Moreover, the - 16 PAH profiles were altered by both moderate and severe burn conditions with the size of aromatic structures following B-Ash > W-Ash > nonburned soils. Neither chlorinated nor brominated PAH concentration was significantly elevated by moderate or severe wildfire. Overall, fire intensity is critical in regulating soil PAH concentrations and profiles. Given the high erodibility of wildfire ash, these PAHs can be easily transported to rivers and reservoirs where they could impact the aquatic food web and drinking source water.

Numerous antibiotics have been detected in aquatic ecosystems and induced severe toxic effects on aquatic organisms. However, mechanisms of bioaccumulation and trophic transfer of antibiotics are not adequately discussed, to the best of our knowledge. In this context, the bidirectional selective effect values (BSEV) and trophic transfer efficiency ratio (TTER) of 24 antibiotics in a simulated food chain (Chlorella sorokiniana-Daphnia magna-Danio rerio) were first calculated to mirror the bioaccumulation and biomagnification. Based on estimates above, the multi-output machine learning (ML) models, including K nearest neighbor (KNN), Support vector machine (SVM), Extremely randomized trees (ERT) and Extreme gradient boosting (XGBoost), were constructed, followed by molecular dynamics (MD) simulation and density functional theory (DFT) calculation to explore the bioaccumulation and biomagnification mechanism. According to our results, sulfonamide antibiotics had greater capacity biomagnification, while β-lactam and tetracycline antibiotics showed opposite results. Meanwhile Cytochromes P450 (CYP450) in Danio rerio played a key role in the food chain. The ERT model exhibited reliable prediction with indicators of R 2 = 0.816, MAE = 0.039, MSE = 0.003, RMSE = 0.053 and MAPE = 8.923. The AATS5s was identified as the most contributing descriptor. The differences in the atomic composition, structure and binding ability to enzymes of antibiotics lead to the differences in their bioaccumulation. Van der Waals interactions (ΔE vdw ) and non-polar interactions (ΔG nonpolar ) were the main driving energy for the biometabolism capability of antibiotics. Tetracyclines are the most readily biometabolized, whereas sulfonamides are more difficult to biometabolize due to their low binding capacity and low reactivity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The toxicity of chemical mixtures may be misestimated, as the assessment of individual chemicals may not adequately reflect their combined toxic effects. However, numerous combinations of chemicals and various interactions make it impossible to measure all possible mixtures. Computational toxicology can help to mitigate this issue, particularly with new methodologies that rely upon alternatives to animal testing. For cosmetic and personal care additives (CPCAs), the ever-increasing of consumption has triggered their complex co-existence in the aquatic environment. To assess their ecological risks, CPCAs experimentally mix at realistic low concentrations with multi-components and different combinations needs to be examined firstly. In this study, toxicity and interactions of multi-component CPCAs mixtures were analyzed taking Daphnia magna as model organism. Also, the contributions of components to the mixture toxicity at different effect levels were discussed. Apparently, the mixture toxicity is closely related to components proportion and impacted by dilution effect. Different forms of combined toxic effects occur in different effect levels. The more components, the less interactions, and the combined toxic effect tends to be additive. Then, Quantitative Structure-Activity Relationship (QSAR) models were developed and evaluated to predict the aquatic toxicity of CPCAs mixtures at various effect levels. The model performance at the median effect level is the best. The descriptors associated most to the toxicity response of CPCA multi-component mixtures are autocorrelation and radial distribution function (RDF), which provide structural information about the spatial distribution of electronic properties and atomic mass., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

There are enormous differences in benzo[a]pyrene (BaP) acute toxicity tests on Daphnia magna , according to previous publications. The explanations of the reasons for this extreme variation are necessary. In this context, the acute toxicity tests of different experiment conditions (light/dark, culture medium, and solvent) were conducted on Daphnia magna with BaP as the toxicant of concern. Based on the experiments above, molecular dynamics (MD) simulations were employed to investigate the mechanisms of action. According to our results, the significant influence of light exposure on the acute toxicity test of BaP ( p < 0.05) on D. magna was recorded. On the basis of the MD simulations, it was possible that BaP may not affect the normal operation of Superoxide Dismutase and Catalase directly, and it could be quickly transferred from the body through Glutathione S-transferase and Cytochromes P450. Therefore, when exposed to light, the oxidative stress process intensifies, causing damage to Daphnia magna . Apparently, the ecotoxicity tests based on inhibition for D. magna cannot adequately reflect the toxic effects of BaP.

Heavy metals and metalloids (HMMs) inhibit the biodegradation of organic pollutants. The degree of inhibition depends not only on the concentration and bioavailability of HMMs but also on additional factors, such as environmental variables (e.g., inorganic components, organic matter, pH, and redox potential), the nature of the metals, and microbial species. Based on the degradation pattern and metal concentrations causing half biodegradation rate reductions (RC50s), the inhibition of biodegradation was: Hg 2+ , As 2 O 3  > Cu 2+ , Cd 2+ , Pb 2+ , Cr 3+  > Ni 2+ , Co 2+  > Mn 2+ , Zn 2+  > Fe 3+ . Four patterns were observed: inhibition increases with increasing metal concentration; low concentrations stimulate, while high concentrations inhibit; high concentrations inhibit less; and mild inhibition remains constant. In addition, metal ion mixtures have more complex inhibitory effects on the degradation of organic pollutants, which may be greater than, similar to, or less than that of individual HMMs. Finally, the inhibitory mechanism of HMMs on biodegradation is reviewed. HMMs generally have little impact on the biodegradation pathway of organic pollutants for bacterial strains. However, when pollutants are biodegraded by the community, HMMs may activate microbial populations harbouring different transformation pathways. HMMs can affect the biodegradation efficiency of organic pollutants by changing the surface properties of microbes, interfering with degradative enzymes, and interacting with general metabolism., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Nanoplastics (NPs, diameter <1 μm) not only have toxicity but also change the toxicity of other pollutants in water. To date, the nanopolystyrene (nano-PS) size effect and its combined toxicity with halogenated polycyclic aromatic hydrocarbons (HPAHs) remain unclear. In this study, the single toxicity, combined toxicity, and mode of action of the binary mixture of polystyrene (PS) and HPAH were examined. At the same time, the nano-PS size effect on combined toxicity was also discussed. According to our results, the 48 h acute toxicity test results showed that 30 nm PS was highly toxic (EC 50 -48 h = 1.65 mg/L), 200 nm PS was moderately toxic (EC 50 -48 h = 17.8 mg/L), and 1 μm PS was lowly toxic (EC 50 -48 h = 189 mg/L). The NP toxicity decreased with increasing size. HPAHs were highly toxic substances to Daphnia magna (EC 50 -48 h = 0.12-0.22 mg/L). The mode of action of PS and HPAHs was antagonistic according to the toxicity unit method (TU), additive index method (AI), and mixture toxicity index method (MTI). The size effect of nano-PS operates via two mechanisms: the inherent toxicity of nano-PS and the sorption of pollutants by nano-PS. The former impacts the combined toxicity more than the latter. In the binary mixed system, the larger the particle size and the higher the proportion of NPs in the system, the less toxic the system was. Linear interpolation analysis can be used to predict the combined toxicity of a mixed system with any mixing ratio., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The initial step in the assessment of the ecological risk of pollutants is to determine the predicted no-effect concentration (PNEC). However, ecological risk assessments of eight carcinogenic polycyclic aromatic hydrocarbons (PAHs), including dimethylbenz[a]anthracene (DMBA), methylcholanthrene (MCA), benzo(a)anthracene (BaA), chrysene (CHR), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP), and dibenzo(a,h)anthracene (DBA), are rarely conducted due to the lack of their PNECs based on test data. In this study, quantitative structure-activity relationship (QSAR) models and interspecies correlation estimation (ICE) models were combined to predict the acute toxicity of these eight target PHAs. A Kolmogorov-Smirnov analysis for species sensitivity distributions (SSDs) of native and all species was conducted. There was no significant difference between the predictions for native Chinese species and the predictions for all species by the QSAR-ICE models. In addition, the feasibility of the QSAR-ICE models was demonstrated by comparing the SSD curves constructed by measured toxicity data of BaP and those predicted by the QSAR-ICE models. The PNECs of the eight PAHs were estimated based on the SSDs and acute to chronic ratio (ACR) method; these data were 0.071 μg/L, 0.033 μg/L, 0.049 μg/L, 0.114 μg/L, 0.019 μg/L, 0.021 μg/L, 0.038 μg/L and 0.054 μg/L for DMBA, DBA, BaP, MCA, BaA, CHR, BbF, BkF, respectively. The higher PNECs of the alkylated PAHs suggested their lower ecological risks. Based on the mixed risk quotient (mRQ) of PAHs through the concentration addition (CA) model, high ecological risk watersheds, such as the Songhua River (mRQ = 1.95), the Liao River (mRQ = 4.59), and the Huai River (mRQ = 1.93), were identified., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Wastewater treatment plants (WWTPs) are usually considered gateways for microplastics (MPs) to enter the environment because large amounts of sewage are produced and MPs are incompletely removed during treatment processes. However, the contribution of effluent MPs to aquatic environmental pollution and that of sludge application to MPs in agricultural soil are still unknown. This study examines the presence of MPs in sewage and sludge in Shenzhen WWTPs and estimates the annual mass loading of MPs from WWTPs to surface water and farmland soil in China. According to our results, for Shenzhen, the annual contribution of MPs from WWTPs (which was obtained by multiplying the annual treated sewage volume by the estimated MP density in the treated sewage) to surface water could be 70.6-302 tons. With a normalized extrapolation model of population density, the contribution of national urban WWTPs to MPs in surface water was estimated to be 734 -3.10 × 10 3 tons/year, of which 220-950 tons/year entered the marine environment. Furthermore, the riverine flux of MPs from WWTPs to the ocean amounts to at least 7.0%-30% based on the maximum value of WWTP contribution to MPs in surface water. For sludge, the potential contribution of MPs to agricultural soil from Shenzhen WWTPs is (1.00-2.80) × 10 3 tons/year. With the above calculation procedure, it was estimated that the contribution of MPs to farmland from sludge application in China is (1.30-3.90) × 10 4 tons/year. The source appointment results for MPs in China's agricultural soil suggested that the contributions of the main four sources, namely, atmospheric deposition, agricultural mulch film, sludge application, and organic fertilizers, are 52%, 30%, 11%, and 7.0%, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

As emerging environmental contaminants, cosmetic and personal care additives (CPCAs) may have less oversight than other consumer products. Their continuous release and pseudopersistence could cause long-term harm to the aquatic environment. Since CPCAs generally exist in the form of mixtures in the environment, prediction and analysis of their mixture toxicity are crucial for ecological risk assessment. In this study, the acute toxicity of five typical CPCA mixtures to Daphnia magna was tested. The combined toxicity of binary mixtures was examined with the traditional concentration addition (CA) and independent action (IA) model. Overall, the synergistic effect of the five CPCAs may be caused mainly by methylparaben. In addition, reliable approaches for quantitative structure-activity relationship (QSAR) model development were explored. Specifically, 18 QSAR models were developed by three dataset partitioning techniques (Kennard-Stone's algorithm division, Euclidean distance based division, and sorted activity based division), two descriptor filtering methods (genetic algorithm and stepwise multiple linear regression) and three regression methods (multiple linear regression, partial least squares and support vector machine). Sixteen equations were applied for the calculation of the mixture descriptors to screen the functional expression of the mixture descriptors with the largest contribution to the mixture toxicity. A new comprehensive parameter that integrates internal and external validation was proposed for QSAR models evaluation. The mixture toxicity is mainly related the 3D distribution of atomic masses and the spatial distribution of the molecule electronic properties. Rigorously validated and externally predictive QSAR models were developed for predicting the toxicity of binary CPCAs mixtures with any ratio, in the applicability domain. The best possible work frame for construction and validation of QSAR models to provide reliable predictions on the mixture toxicity was proposed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

As a kind of ubiquitous emerging pollutant, microplastics (MPs) are persistent in the environment and have a large impact on the ecosystem. Fortunately, some microorganisms in the natural environment can degrade these persistent MPs without creating secondary pollution. In this study, 11 different MPs were selected as carbon sources to screen the microorganisms for degradable MPs and explore the possible mechanism of degradation. After repeated domestication, a relatively stable microbial community was obtained after approximately 30 days later. At this time, the biomass of the medium ranged from 88 to 699 mg/L. The growth of bacteria with different MPs ranged from 0.030 to 0.090 optical density (OD) 600 of the first generation to 0.009-0.081 OD 600 of the third generation. The weight loss method was used to determine the biodegradation ratios of different MPs. The mass losses of polyhydroxybutyrate (PHB), polyethylene (PE), and polyhydroxyalkanoate (PHA) were relatively large, at 13.4%, 13.0%, and 12.7%, respectively; these figures for polyvinyl chloride (PVC) and polystyrene (PS) were relatively slight, 8.90% and 9.10%, respectively. The degradation half-life (t 1/2 ) of 11 kinds of MPs ranges from 67 to 116 days. Among the mixed strains, Pseudomonas sp., Pandoraea sp., and Dyella sp. grew well. The possible degradation mechanism is that such microbial aggregates can adhere to the surface of MPs and form complex biofilms, secrete extracellular and intracellular enzymes, etc., break the hydrolyzable chemical bonds or ends of molecular chains by attacking the plastic molecular chains, and produce monomers, dimers, and other oligomers, leading to the reduction of the molecular weight of the plastic itself.

Nanoparticle (NP)-coated (immobilized) bacteria are an effective method for treating environmental pollution due to their multifarious benefits. This review collates a vast amount of existing literature on organic pollution treatment using NP-coated bacteria. We discuss the features of bacteria, NPs, and decoration techniques of NP-bacteria assemblies, with special attention given to the surface modification of NPs and connection mechanisms between NPs and cells. Furthermore, the performance of NP-coated bacteria was examined. We summarize the factors that affect bioremediation efficiency using coated bacteria, including pH, temperature, and agitation, and the possible mechanisms involving them are proposed. From future perspectives, suitable surface modification of NPs and wide application in real practice will make the NP-coated bacterial technology a viable treatment strategy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Traffic emissions and waste incineration are the main sources of PAHs in urban atmosphere, but their spatially superimposed effects are currently unclear. This study assessed the spatial distribution of PAHs and HPAHs concentrations in the atmosphere of Shenzhen by simulating the spatial and temporal dispersion of PAHs and HPAHs emissions from on-road vehicles and municipal solid waste incinerators (MSWIs). Generally, the concentrations of PAHs and HPAHs were higher on workdays than on weekends due to higher traffic volumes, while the prevailing wind direction of the northeast could cause more widespread dispersion of PAHs and HPAHs within Shenzhen's atmosphere. After superimposing the spatial distribution of pollutants emitted by vehicles and MSWIs, PAHs within 1000 m downwind of MSWIs are mainly contributed by MSWIs and beyond 1000 m by vehicles. The cancer risk values induced by exposure to PAHs and HPAHs via inhalation in Shenzhen were below the acceptable risk level for males and females in each age group, while adults faced the highest cancer risk, followed by adolescents and children. However, spatially, the cancer risk values were above the priority risk level for adult males in localized high-traffic areas in Futian and Luohu districts., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Halogenated PAHs (HPAHs) are ubiquitous in the environment and have a toxicity similar to that of dioxin. Microplastics exist widely in the environment, and their sorption allows them to act as carriers of HPAHs, potentially changing the bioavailability of HPAHs. However, to the best of our knowledge related studies are limited. In this study, degrading bacteria of five HPAHs were cultivated from mangrove sediments. Among them, the Hyphomicrobium genus has good degradation ability on 9-BrAnt, 2-BrPhe and 2-ClPhe. The degradation process is in line with the first-order degradation kinetic characteristics. The kinetic equations of five kinds of HPAHs showed that the degradation half-lives are 0.65 days (2-BrFle), 0.79 days (9-ClPhe), 1.50 days (2-ClAnt), 5.94 days (9-BrPhe) and 14.1 days (9-BrAnt). The greater the number of benzene rings and the heavier the halogen substituents, the slower the degradation of HPAHs. The sorption of microplastics inhibited the biodegradation of HPAHs, and the degradation half-life of HPAHs will be extended from 0.65 to 14.1 days (the average is 4.59 days) to 1.71-9.93 days (average 5.40 days) for PA, 0.70-35.2 days (average 12.8 days) for PE, 6.02-28.2 (average 15.7 days) days for POM, and 4.60-24.0 (average 19.2 days) days for PP, which is mainly related to the partition coefficient between microplastics and water. This study provides a reference for reducing the uncertainty of the ecological risk assessment of HOCs in the aquatic environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Compound-specific isotope analysis has been demonstrated to be a powerful tool for the assessment of in situ pollutant degradation. Enrichment factor, an essential and prerequisite parameter, could be determined under simulated control laboratory in advance. However, different microbial community composition and substrate availability may significantly affect the accuracy of simulated enrichment factor. Here, a modified mathematic method of two dimensional is proposed to quantify the extent of pollutant degradation involving the break of carbon and hydrogen bond. In this new model, the laboratory cultures used to determine carbon or hydrogen enrichment factors in advance could be canceled and the key point to assess the extent of biodegradation is only determining the value of Λ ri (dual C-H isotope slope calculated with a self-modified model) in the field investigation. As a new and convenient method, this math model greatly facilitates the investigation of pollutant degradation extent under field conditions. Two approaches are applied to evaluate the proposed model. With our model, the estimated results based on C isotope are consistent with those measured values, while those based on H isotope are unsatisfactory. This can be attributed to the differences in accuracy of C-H isotope determinations. Overall, enrichment factors and biodegradation rates calculated with the proposed model are comparable with those measured figures., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

The photodegradation of two phthalic acid esters (PAEs), dimethyl phthalate (DMP) and di-n-octyl phthalate (DOP), under simulated sunlight in aqueous or organic phases (n-hexane (HEX) and dichloromethane (DCM)) was investigated. The mean photodegradation rates were ranked by half-lives as follows: DOP in DCM (3.77 h) < DMP in DCM (9.62 h) < DOP in H 2 O (3.99 days) < DMP in H 2 O (19.2 days) < DOP in HEX (21.0 days) < DMP in HEX (>30 days). Compound-specific stable isotope analysis (CSIA) combined with intermediate analysis was employed to explore the involved initial photoreaction mechanism. C-O bond cleavage, chlorine radical adduction to the aromatic ring, competing reactions of chlorine radical adduction to the aromatic ring and side chain, and a singlet oxygen-mediated pathway were mainly responsible for initial photodegradation mechanism of PAEs in H 2 O, DMP in DCM, DOP in DCM, and DOP in HEX, respectively. Furthermore, distinct isotope fractionation patterns of PAEs photodegradation open the possibility of using CSIA to differentiate the involved solvents in the field. More toxic and recalcitrant intermediates emerged during the photodegradation of DMP in DCM, while the risk to human health was reduced during the photochemical transformation of DOP in organic solvents., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Agricultural plastic film (APF) is widely used in modern agriculture. Under natural environmental conditions, the structure, surface properties and mechanical properties of APFs change because of sunlight, wind and other factors and gradually break into debris, resulting in the generation of microplastics (MPs). Studies have reported that the MPs concentration in soil is positively correlated with the use intensity and duration of APFs. Unfortunately, to the best of our knowledge, no method to measure the emissions of in situ APFs has been developed. In this study, the effects of mechanical abrasion driven by wind on MPs fragmentation by polyethylene (PE) and polyvinyl chloride (PVC) APFs with the increase of exposure time were investigated. Meanwhile, based on the release rate model of PS fragmented MPs under natural sunlight, a modified model to quantify the effect of ultraviolet (UV) radiation exposure duration on the production of APF fragmented MPs was developed. Based on these models, the amount of MPs produced from APFs in farmland in China was estimated. The national annual MPs mass emissions from APFs in agricultural soil were approximately 5 × 10 4 to 6.8 × 10 4  tons in 2018 due to wind and 6.5 × 10 3  tons due to sunlight, and the total emission level due to both wind and sunlight was 5.1 × 10 4 to 7.0 × 10 4  tons. Compared with that of wind, the contribution of UV radiation to MPs emission is smaller. Our estimates are comparable to data reported in previous studies, indicating that our models have good practical applications and are of great significance for predicting MPs production from APFs in farmland., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Environmental molecular markers can be used to understand the sources, transport, and fate of pollutants. Furthermore, they can also be applied to assess the influences of anthropogenic activities and elucidate urbanization from different perspectives. In this study, the potential of linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs) as chemical indicators of urbanization was examined first. Overall, the concentrations of LABs and PAHs ranged from 5.49-148 ng/g (mean: 15.6, median: 9.33) and 3.61-4878 ng/g (mean: 181, median: 71.3), respectively. Owing to the different sources and input methods of these two substances in soil, the area-weighted median values for LABs were more suitable to assess the magnitude of contamination on the administrative scale. For PAHs, the average values were more practical. LAB (consumption-induced pollutants) and PAH (production-induced pollutants) concentrations exhibited good correlations with some indices for residential daily life and industrialization, which indicated that soil can be utilized to reveal multidimensional urbanization-environment relationships. Two different patterns, the inverted U-shaped pattern and the upward pattern, were employed to simulate the environment-urbanization relationships in Shenzhen, China, which indicated that raising the standard of living or industrialization had created different soil pollution. The environmental quality demand was more difficult to meet by changing the energy structure than by improving infrastructure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Agricultural mulch film (AMF) is deemed an important source of microplastics (MPs) in agricultural soil (AS). However, quantitating the contribution of AMFs to MPs in farmland soil and surface water remains a considerable challenge to date. In the present study, a basic framework was developed to address these concerns. First, the concentrations of MPs in soil derived from AMF abrasion (C MP ) and the total MPs from all sources in AS (C TMP ) were measured. Then, the ratios of C MP to C TMP , i.e., the contribution of AMFs to MPs in AS, were calculated. The contribution of AMFs to MPs in surface water via soil erosion was calculated based on C TMP values, the ratios of C MP to C TMP , soil erosion intensities (SEIs), and farmland areas. Furthermore, the potential contribution of soil erosion to MPs in the ocean was estimated. In China, the inventory of MPs in surface AS in 2018 ranged from 4.9 × 10 6 to 1.0 × 10 7 tons according to our results. AMFs contributed 10%-30% of the C TMP with certainties of 60-95%. Assuming that all MPs in AS can be exhaustively transferred to surface water via soil erosion, the national mass transfer amount of MPs (MT TMP ) from AS to surface water reached 1.2 × 10 5 -2.2 × 10 5 tons (∼2% of the inventory of MPs in the AS of China); the fluxes of MPs into the ocean from AS were 3.4 × 10 4 -6.6 × 10 4 tons, assuming that all MPs in the AS of coastal provinces enter the ocean. It is likely that AMFs contributed 10%-30% MT TMP and fluxes of MPs to the ocean according to the ratios of C MP to C TMP . Apparently, approximately 30% of the national MT TMP (i.e., the rate of MP flux to the ocean to MT TMP ) was input to the ocean., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The complex interactions of contaminants with microplastics significantly affect ecological risk assessments. Studies of the sorption behavior of freely dissolved hydrophobic organic contaminants (HOCs) on microplastics are common. However, concentrations of HOCs in the actual aquatic environment sometimes exceed their water solubility. A possible explanation is that a microplastic-sol-water three-phase medium (TPM) is formed in the actual water environment. Both states HOCs (in solute and sol) have the potential to migrate to particles suspended in water. To confirm this view, four kinds of microplastics and eight halogenated polycyclic aromatic hydrocarbons (HPAHs) were selected to examine the partitioning of HPAHs between microplastics and water (sol and solute). Both monolayer and multilayer coverage of HPAHs onto microplastics occurred, and chemical sorption dominated the pseudo-sorption mechanism. The microplastic-water partition ratios of HPAHs (0.12-0.74) were approximately four to five orders of magnitude lower than their corresponding K OW values, suggesting that mechanisms other than sorption were involved. Apparently, the sol HPAHs contributed almost identically large increments to both microplastics and water, and closed the gap. For microplastic-supported HPAHs, the contribution of the sol fraction was more than triple that of the dissolved fraction; the key influencing factor was the water solubility of HPAHs., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Global consumption of disposable plastic tableware (DPT) is massive because it is durable, light and inexpensive. Using the life cycle assessment method, we found that DPT for per person per meal emitted 597 g of CO 2 and was far more than that of reusable plastic tableware (RPT, 7.00 g), ceramic tableware (9.55 g) and straw tableware (14.6 g). If the demand growth for DPT continues, 416 MT of CO 2 will be emitted due to DPT consumption by 2050 globally. We further explored strategies to reduce CO 2 emissions by examining the life cycles of four types of tableware according to sensitivity analysis. According to our results, if the recycling rate of DPT reaches 60% at the end-of-life stage, 50% of CO 2 emissions can be cut; if dishwashing instead of hand washing is used to clean RPT, ceramic, and straw tableware, approximately 64%, 71%, and 23% of CO 2 emissions can be reduced, respectively. If 60% of DPT is replaced by RPT, this plastic tableware will halve carbon emissions. If the rate reaches 100%, carbon emissions will be reduced by 92%. Although the CO 2 emissions of the three types of tableware other than DPT are relatively small, RPT will bring other environmental burdens and human health risks, ceramic tableware is bulky and its additives are toxic. Straw tableware combines practical and safety performance. The results show that the choice of straw tableware plays a significant role in curbing the greenhouse effect without compromising consumer safety., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Two-dimensional compound-specific isotope analysis has become a powerful tool for distinguishing reaction mechanisms. Lambda (Λ), an essential and important parameter for processing two-dimensional isotope fractionation data, exhibits values specific to a reaction mechanism. In the present article, we modified the existing algorithms for calculation of lambdas based on a review of current methods. Specifically, by regressing [(1000+δE 0,2 )*(n 1 *x 2 )*ΔδE bulk,1 ] versus [(1000+δE 0,1 )*(n 2 *x 1 )*ΔδE bulk,2 ] by the York method, a novel method was developed to calculate Λs. The improved method eliminates both the influence of the nonreacting position and the initial isotope signatures. Furthermore, this method retains the advantages of a two-dimensional isotope plot, which eliminates contributions from commitment to catalysis, does not require determination of the fraction of remaining substrate, and can be constructed even from field data. Additionally, the one-sample t test is applied to generate a 95% confidence interval of the dataset of Λ ri s for various reaction mechanisms. The ranges of 5.67-24.8, 8.54-9.80, 0.51-8.35, 25.2-36.8, and 7.09-21.9 are applicable for the oxidation of C-H bonds (Z C =1, Z H =3; Z C and Z H are the number of indistinguishable carbon and hydrogen atoms in intramolecular competition, respectively), oxidation of C-H bonds (Z C =1, Z H =4), aerobic biodegradation of benzene (Z C =6, Z H =6), methanogenic or sulfate-reducing biodegradation of benzene (Z C =6, Z H =6), and nitrate-reducing biodegradation of benzene (Z C =6, Z H =6). The accumulation and correction of these values will make the data measured in the field easier to interpret.

The e-waste problem needs be tackled under a global framework, based upon the understanding that e-waste is a global issue and thus a shared responsibility. To illustrate this point, a cost-benefit analysis of metal recovery from e-waste was conducted with Europe, North America and China as representative regions of e-waste producers. The final profit associated with the entire e-waste recycling process was estimated by deducing the energy costs of metal recovery from the revenues of the manually dismantling stage and the metal recovery stage. Then, the potential job opportunities were estimated based on the final profit from the local e-waste recycling and average wage per year. Overall, profits of manually dismantling 1 ton of e-waste varied widely, but the final profits were positive. The potential job opportunities generated by local e-waste recycling ranged from 4.65 × 10 5 person/year for North America to 2.03 × 10 6 for China person/year. According to our study, the environmental load of 1 kg of e-waste would be 1-9 USD, indicating that this is the cost required to offset the environmental consequences of each kilogram of e-waste. By applying environmental load to per capita, the concept can act as a tool to encourage countries to fairly share the environmental responsibility of e-waste based on their e-waste generation. Based on this, we propose an e-waste emissions trading system that set a cap on the total amount of e-waste that could be generated globally and per country, to reduce e-waste and carbon emissions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Microplastic had been commonly used in personal care products (PCPs) until it was documented to be a pollutant. The relative contents of microplastics in PCPs decrease in the order of the USA, Europe, and Asia. The geometric means of the abundance and mass of microplastics found in PCPs were 2162 particles/g and 0.04 g/g, respectively. Diameters of PCP-derived microplastics are less than 350 μm. To quantify the exact contribution of PCPs to microplastic pollution, this review surveyed the existing scientific literature and statistically integrated the findings from 88 literatures. Overall, approximately 1500 tons/year of microplastics from PCPs escape from WWTPs and enter the global aquatic environment. According to the PCP consumption and microplastics levels, the mass emission of global PCP-derived microplastics reach up to 1.2 × 10 4 tons/year. The two figures account for ~0.1% and ~ 0.8% of the annual global release of primary microplastics in the world oceans (~1.5 × 10 6 tons/year). In the last 50 years (1970-2019), up to 3.00 × 10 5 tons of PCP-derived microplastics have accumulated in the environment. The main plastic in PCPs is polyethylene, which is known for being a remarkably resistant polymer to degradation. Even if microbeads are completely banned globally in 2020, microplastics that have been discharged into the environment will still persist for a long time and claim our highest attention. This review provided primary information to deal effectively with the problem of PCP-derived microplastic both now and in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Plastic film has allowed manufacturers to meet varied marketplace demands. Typically, its usage can be divided into two general categories-packaging (food, nonfood and other) and nonpackaging. The microplastics emission resulting from wearing of plastic film is unavoidable in the process of production and use. Currently, no reliable method exists for measure emission factor (EF) of microplastics by mechanical abrasion (MA). In the present study, a simple but effective approach to quantify EF of microplastic by MA was developed. Specifically, the relative light transmittance (RLT) of the plastic film is decreased with increase of MA degree. This quantitative relationship between the two factors can be applied to determine EFs of microplastics induced by MA. The method developed in this study is easy and feasible, but it still has limitations in the standpoint and range, the direction of worthiness of theory., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In China, the total annual atmospheric emission of 16 polycyclic aromatic hydrocarbons (PAHs) reach up to approximate 100 thousand tons, part of which is preserved in soils. In this study, the contribution of soil erosion to PAHs in surface water nationwide was quantified. The results indicate that a major portion of the annual PAHs emission is lost from soils via rainfall erosivity and subsequently transported to the ocean. The national annual flux of PAHs from soil to surface water by the natural physical forces of water measures up to ~70 thousand tons, which accounts for ~62% of the annual emission of PAHs with 19% entering the sea directly. In general, both the soil erosion intensity and flux of PAHs for the regions located in the Southeast of China are over those in the Northwest of China, with the regions being divided into two different parts by the famous geographic "Hu Huanyong line", reflecting the intensive impact of human activities on environmental degradation. Comparative analysis suggested that there must be a big fraction of PAHs lost during transmission due to the river sedimentation and lake dispersion. This study closes a major gap in the national budget of PAHs and provides critical information in the context of regional environment risk assessment., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Electronic commerce has been becoming the new driver of the retail industry. The large-scale expansion of electronic commerce with additional packaging certainly increases stress on the environment. However, a comparative analysis of environmental impacts of electronic commerce and conventional retail trade channels is unavailable. In this study, an Average Package Difference Model (APDM) was developed to evaluate CO 2 emissions difference via the two retail channels in Shenzhen, China based on a life-cycle perspective. In the meanwhile, the national emission was estimated by the above results. Our results suggest that conventional retail has a higher environmental cost than that of electronic commerce, especially during shopping trips. Specifically, average CO 2 emission difference per package in terms of product returns, packaging, buildings and transportation were 0.14 ± 0.03, 0.84 ± 0.08, 0.67 ± 0.04, 1.3 ± 0.26 kg, respectively. CO 2 is mainly emitted from buildings and consumer trips in conventional retail trade, whereas packaging is mainly responsible for CO 2 emission in e-commerce. In China, the total CO 2 emission difference between conventional retail and electronic commerce was 124 million tons in 2016. Growth of the proportion of electronic commerce will contribute to lower CO 2 emissions induced by the entire retail industry. Actually, carbon emissions can be reduced in both conventional retail and electronic commerce, such as the reusable packaging, opening shopping centers in dense population zones and promoting the usage of public transportation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

With a self-designed small-scale waste incinerator, emission behaviors of parent and halogenated polycyclic aromatic hydrocarbons (PAHs and HPAHs) were simulated and visualized. According to our results, the 2-3 ring PAHs have higher emission factors (EFs) than those of the 4-6 ring PAHs during waste incineration. The EFs of individual HPAHs are comparable in all incineration products. Overall, the EFs of Ʃ 16 PAH and Ʃ 3 ClPAH decreased in the order of gas > bottom ash > particle > fine particle while the EF order for Ʃ 6 BrPAH is bottom ash > particle > gas > fine particle. Based on qualitative observation, the size distributions of Σ 16 PAH, Σ 3 ClPAH, and Σ 6 BrPAH were characterized by trimodal peaks. Coagulation of fine particles in air may lead to enrichment of target compounds in the coarse particle fraction. The gas-particle partition did not reach theoretical equilibrium and most PAHs and HPAHs were absorbed inside the organic carbon. Estimated mass emission of target compounds in Shenzhen suggests that the gaseous phase from MSW incineration is the major contributor to the urban environment. However, automotive emissions contribute more to urban air pollution than MSW incineration in Shenzhen. Generally, compared with other real waste treatment, waste incineration is a more efficient method for waste-to-energy recovery and produces fewer pollutants, although the resultant carcinogenic substances are never truly harmless., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Since the creation of first man-made plastic, the global production and consumption of plastics have been continuously increasing. However, because plastic materials are durable and very slow to degrade, they become waste with high staying power. The over-consumption, disposal, and littering of plastics result in pollution, thus causing serious environmental consequences. To date, only a fraction of waste plastics is reused and recycled. In fact, recycling plastics remains a great challenge because of technical challenges and relatively insufficient profits, especially in mixed plastics. This review focuses on an environmentally friendly and potentially profitable method for plastics separation and recovery and solvents extraction. It includes the dissolution/reprecipitation method and supercritical fluid extraction, which produce high-quality recovered plastics comparable to virgin materials. These methods are summarized and discussed taking mass-produced plastics (PS, PC, Polyolefins, PET, ABS, and PVC) as examples. To exploit the method, the quality and efficiency of solvent extraction are elaborated. By eliminating these technical challenges, the solvent extraction method is becoming more promising and sustainable for plastic issues and polymer markets., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This study reports results from a tunnel experiment impact of real-world traffic-related particle and gas parent and halogenated polycyclic aromatic hydrocarbons (PAHs and HPAHs) on urban air. The traffic related emission characteristics and subsequent environmental behavior of these compounds were investigated. To understand the significance of real-world transport emissions to the urban air, traffic-related mass emissions of PAHs and HPAHs were estimated based on measured emission factors. According to our results, PAHs and HPAHs emissions via particulate phase were greater than those via gaseous phase; particles in 2.1-3.3 μm size fraction, have the major contribution to particulate PAHs and HPAHs emissions. Over all, contribution of traffic-related emission of PAHs (only ∼3% of the total PAHs emission in China) is an overstated source of PAHs pollution in China. Actually, exhaust pipe emission contributed much less than the total traffic-related emission of pollutants., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The quality of indoor environments has a significant impact on public health. Usually, an indoor environment is treated as a static box, in which physicochemical reactions of indoor air contaminants are negligible. This results in conservative estimates for primary indoor air pollutant concentrations, while also ignoring secondary pollutants. Thus, understanding the relationship between indoor and outdoor particles and particle-bound pollutants is of great significance. For this reason, we collected simultaneous indoor and outdoor measurements of the size distribution of airborne brominated flame retardant (BFR) congeners. The time-dependent concentrations of indoor particles and particle-bound BFRs were then estimated with the mass balance model, accounting for the outdoor concentration, indoor source strength, infiltration, penetration, deposition and indoor resuspension. Based on qualitative observation, the size distributions of ΣPBDE and ΣHBCD were characterized by bimodal peaks. According to our results, particle-bound BDE209 and γ-HBCD underwent degradation. Regardless of the surface adsorption capability of particles and the physicochemical properties of the target compounds, the concentration of BFRs in particles of different size fractions seemed to be governed by the particle distribution. Based on our estimations, for airborne particles and particle-bound BFRs, a window-open ventilated room only takes a quarter of the time to reach an equilibrium between the concentration of pollutants inside and outside compared to a closed room. Unfortunately, indoor pollutants and outdoor pollutants always exist simultaneously, which poses a window-open-or-closed dilemma to achieve proper ventilation., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Two waste incinerators were selected for investigation of size-dependent emission characteristics of airborne parent and halogenated PAHs (PAHs and HPAHs) and incidence of these pollutants from trash incineration. The concentrations of total PAHs (gas and particles with aerodynamic diameter 0.43-10 μm) in ambient air of Shenzhen incinerators were at the lower end of the global range while those of HPAHs were higher than those of urban air in other studies. High-ring PAHs dominated in PM 2.5 (66%-86%), while low-ring PAHs dominated in PM 10 (83%-86%). As for PAHs in gaseous phase, low-ring PAHs were collectively account for 86%-97%. ΣHPAH mainly enriched in coarse particles (>83%). The size distributions of ΣPAH and ΣHPAH were both characterized by bimodal peaks dominate in 9.0-10 μm and subordinate in 4.7-5.8 μm. PAHs and HPAHs enrichment in the coarse particles indicates that particle-bound PAHs and HPAHs from incinerators cannot travel great distances. Model simulation results showed the peak of airborne PAHs and HPAHs occurred in approximate 300 m from incinerator, then their concentrations reduced sharply. The extent of affected areas by municipal solid waste incinerators (MSWIs) seem very large, intensity of impacts can be neglected for the very low level of pollutants. Although waste incineration is perceived as most polluting way to manage waste, our study found the damage from incinerator to be far less than originally feared., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Overall, total exhaust emissions of NO X , VOC and particulate matter (PM) declined, though vehicles in use continued to increase in China. This suggested that contribution of motor vehicle exhaust to haze in China may be exaggerated. A higher frequency of haze episodes in China with lower total emissions fraction from vehicle exhaust compared with those in the USA confirmed that there exists no strict causality between vehicle and haze. No significant correlation (p<0.05) between haze days and the contribution of vehicles to airborne PM 2.5 (particulates that are <2.5μm in aerodynamic diameter) or car ownerships. All results revealed again that vehicle exhaust is an overstated cause for haze formation in China., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Eight low-ring PAHs were detected in 21 polystyrene (PS) food contact materials (FCMs) samples while high-ring PAHs (>4 rings) were not found. This is because the reaction pathway for formation of high-ring PAHs consists of more steps than it does for low-high PAHs. The concentrations of Σ 8 PAH were from 18.9±5.16ng/g for product colorless fruit fork to 476±52.0ng/g for foam instant noodle container. These data were far beyond levels of PAHs in other plastics. Of the eight PAHs detected, Phe had the highest average concentration, followed by Nap. These two PAHs collectively accounted for over 80% of the Σ 8 PAH concentrations in all PS FCMs. Levels of Σ 8 PAH in expanded PS FCMs were higher than those in extruded ones due to utilization of foaming agent. The concentrations of Σ 8 PAH were lower in colorless PS FCMs than in colored ones. Auxochromes and chromophores contributed to the change of short-chain hydrocarbons to aromatic hydrocarbon. Simulated migration values of PAHs from PS FCMs to food varied widely. The migration value of Σ 8 PAH with maximum probability was below 10ng/g, which the maximum tolerated migration level for substance according to the European Union standards. However, higher migration values were possible and the potential health risk should still be concerned because the simulated migration displayed a log-normal distribution. Furthermore, water was used as food simulant would always lead to an underestimate of PAHs migration to real daily food, and then lead to an underestimate of risk., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The recovery of four dominant plastics from electronic waste (e-waste) using mixed solvent extraction was studied. The target plastics included polycarbonate (PC), polystyrene (PS), acrylonitrile butadiene styrene (ABS), and styrene acrylonitrile (SAN). The extraction procedure for multi-polymers at room temperature yielded PC, PS, ABS, and SAN in acceptable recovery rates (64%, 86%, 127%, and 143%, respectively, where recovery rate is defined as the mass ratio of the recovered plastic to the added standard polymer). Fourier transform infrared spectroscopy (FTIR) was used to verify the recovered plastics' purity using a similarity analysis. The similarities ranged from 0.98 to 0.99. Another similar process, which was denoted as an alternative method for plastic recovery, was examined as well. Nonetheless, the FTIR results showed degradation may occur over time. Additionally, the recovery cost estimation model of our method was established. The recovery cost estimation indicated that a certain range of proportion of plastics in e-waste, especially with a higher proportion of PC and PS, can achieve a lower cost than virgin polymer product. It also reduced 99.6%, 30.7% and 75.8% of energy consumptions and CO 2 emissions during the recovery of PC, PS and ABS, and reduced the amount of plastic waste disposal via landfill or incineration and associated environmental impacts., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Assessment of surface water pollution by organic pollutants is a top priority in many parts of the world, as it provides critical information for implementing effective measures to ensure drinking water safety. This is particularly important in China, where insufficient data of national scale have been acquired on the occurrence of any organic pollutants in the country's water bodies. To fill the knowledge gap, we employed passive samplers to survey polycyclic aromatic hydrocarbons (PAHs) in 42 freshwaters throughout the country. The dissolved Σ 24 PAH concentrations ranged from 0.28 to 538 ng L -1 , with the highest and lowest values obtained in Southern Lake in Wuhan and in the Nam Co Lake in Tibet, respectively. Average Σ 24 PAH concentrations in West, Central, and East China correlated well with the population densities in these regions. The composition profiles of PAHs showed a mixed PAH source of coal combustion, fossil fuel combustion, and oil spills. In addition, all dissolved PAH concentrations were below the water guidelines developed by the U.S. Environmental Protection Agency, the European Union, and the Canadian government, except for anthracene in Southern Lake. Our results also demonstrated the feasibility of establishing a global network of monitoring organic pollutants in the aquatic environment with passive sampling techniques.

Comprehensive studies on polycyclic aromatic hydrocarbons (PAHs) within an urban river are urgently needed to carry out strategies to limit their contamination and dispersal. Here, we analyzed 16 PAH occurrences in water, suspended particulate matter (SPM), and sediment monthly for a year in the Maozhou River mainstream (Shenzhen, South China). Monthly rainfall positively correlated with both total PAH concentrations in filtered water (water PAHs) and SPM. Sediment PAH concentration increased from the river source to estuary. Compared to the earlier record, the sediment PAHs decreased at almost all sites due to the high-molecular-weight PAH (≥4 rings; especially the 4-ring PAH) degradation, except the estuary site that accumulated more low-molecular-weight PAHs (<4 rings). Results suggest that the water and SPM PAHs had similar and recent sources (e.g., rainfall and storm runoff) and actively exchanged with each other. The sediment PAHs had relatively different and complicated sources (fossil fuel combustion: 44.0%; oil pollution: 28.4%; biomass burning: 27.6%), and showed a long-term accumulation effect and increasingly weaker source-sink relation with both water and SPM PAHs from river source to estuary. This study highlights a disconnection in the source and migration mechanism between the water body (including water and SPM) and sediment PAHs., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Based on the most widely used plastics in China, five plastic wastes were selected for investigation of brominated flame retardant (BFR) emission behaviors during open burning. Considerable variations were observed in the emission factors (EF) of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) from the combustion of different plastic wastes. Distribution of BFR output mass showed that ΣPBDE was emitted mainly by the airborne particle (51%), followed by residual ash (44%) and the gas phase (5.1%); these values for ΣHBCD were 62%, 24%, and 14%, respectively. A lack of mass balance after the burning of the plastic wastes for some congeners (output/input mass ratios>1) suggested that formation and survival exceeded PBDE decomposition during the burns. However, that was not the case for HBCD. A comparison with literature data showed that the open burning of plastic waste is major source of PBDE compared to regulated combustion activities. Even for state-of-the-art waste incinerators equipped with sophisticated complex air pollution control technologies, BFRs are released on a small scale to the environment. According to our estimate, ΣPBDE release to the air and land from municipal solid waste (MSW) incineration plants in China in 2015 were 105 kg/year and 7124 kg/year. These data for ΣHBCD were 25.5 and 71.7 kg/year, respectively. Considering the fact that a growing number of cities in China are switching to incineration as the preferred method for MSW treatment, our estimate is especially important. This study provides the first data on the environmental exposure of BFRs emitted from MSW incineration in China., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

In this study, we selected Shenzhen City as a typical region of urbanization and took Linear alkylbenzenes ( LABs) as an environmental molecular marker to investigate the relationship between soil LABs levels and urbanization indexes on the basis of analysis of spatial distribution of LABs in surface soil. Our results indicated relations between the LABs levels in soil and the five urbanization indexes, such as the population, water supply, urban construction, income and expenditure, as well as industrial structure. These results suggested that LABs levels were correlated with urbanization and could be used as an environmental molecular indicator for the process of urbanization.

In the present study, a similarity analysis method was proposed to evaluate the source-sink relationships among environmental media for polybrominated diphenyl ethers (PBDEs), which were taken as the representative contaminants. Chromatographic fingerprint analysis has been widely used in the fields of natural products chemistry and forensic chemistry, but its application to environmental science has been limited. We established a library of various sources of media containing contaminants (e.g., plastics), recognizing that the establishment of a more comprehensive library allows for a better understanding of the sources of contamination. We then compared an environmental complex mixture (e.g., sediment, soil) with the profiles in the library. These comparisons could be used as the first step in source tracking. The cosine similarities between plastic and soil or sediment ranged from 0.53 to 0.68, suggesting that plastic in electronic waste is an important source of PBDEs in the environment, but it is not the only source. A similarity analysis between soil and sediment indicated that they have a source-sink relationship. Generally, the similarity analysis method can encompass more relevant information of complex mixtures in the environment than a profile-based approach that only focuses on target pollutants. There is an inherent advantage to creating a data matrix containing all peaks and their relative levels after matching the peaks based on retention times and peak areas. This data matrix can be used for source identification via a similarity analysis without quantitative or qualitative analysis of all chemicals in a sample., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Fine roots of woody plants are a heterogeneous system differing markedly in structure and function. Nevertheless, knowledge about the plant uptake of organic pollutants via fine roots is scarce to date. In the present study, plant uptake, translocation, and return of polycyclic aromatic hydrocarbons (PAHs) via fine roots in a subtropical forest ecosystem were investigated. Levels of Σ15PAHs in different fine root branch orders of Michelia macclurei, Cryptocarya concinna, Cryptocarya chinensis, and Canthium dicoccums varied from 5072±1419 ng g(-1) to 6080±1656 ng g(-1), 4037±410 ng g(-1) to 6101±972 ng g(-1), 3308±1191 ng g(-1) to 4283±237 ng g(-1), and 3737±800 ng g(-1) to 4895±1216 ng g(-1), respectively. Overall, concentrations of low-molecular-weight PAHs with 2-3 aromatic rings were higher than high-molecular-weight PAHs with 4-6 aromatic rings in all fine root branch orders. There were obvious translocations of PAHs between adjacent branch orders and a net accumulation of PAHs may occur in the fourth- and fifth-order roots. The storage of PAHs in the fine root system showed an obvious increasing trend along the branch orders ascending for all tree species. The return flux of PAHs via fine roots mortality showed an obvious decreasing trend with the branch orders ascending across the four tree species. Lower order roots contributed greatly to the total PAHs return flux. Our results indicated that fine roots turnover is an effective pathway for perennial tree species to remove environmental toxicants absorbed into them., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Size-fractionated atmospheric particles were collected in the closed room, ventilated room and outdoors in a university campus and analyzed for polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane ( HBCDs). The concentrations of particle-bound ∑ PBDE (sum of four PBDE congeners) indoors were significantly greater than those in other regions and similar to the levels in electronic waste recycling sites. In all the samples, BDE209 and alpha-HBCD were the dominant congener for PBDEs and HBCDs, respectively. The size-fractionated distributions of airborne PBDE displayed bimodal peaks in 0.4-0.7 and 5.8-9.0 microm in the closed room, but only a unimodal peak in 4.7-10.0 microm in the ventilated room and outdoors. For HBCD, approximate 90% HBCD were found on coarse particles (aerodynamic diameter (Dr) > 2.1 microm). The inhalation intake of PBDE and HBCD in closed and ventilated rooms were 22.56-1503 pg x (h x kg)(-1), 0.09- 9.25 pg x (h x kg)(-1) and 13.89-601.1 pg x (h x kg)(-1), 0.07-1.75 pg x (h x kg)(-1), respectively. These estimates were much lower than the exposure via dust ingestion suggesting that inhalation of particle-bound BFRs may not be a vital exposure route.

The levels of seven essential trace elements (Mn, Co, Ni, Cu, Zn, Se, and Mo) and six non-essential trace elements (Cr, As, Cd, Sb, Hg, and Pb) in a total of 89 drinking water samples collected in Shenzhen, China were determined using inductively coupled plasma mass spectrometry (ICP-MS) in the present study. Both the essential and non-essential trace elements were frequently detectable in the different kinds of drinking waters assessed. Remarkable temporal and spatial variations were observed among most of the trace elements in the tap water collected from two tap water treatment plants. Meanwhile, potential human health risk from these non-essential trace elements in the drinking water for local residents was also assessed. The median values of cancer risks associated with exposure to carcinogenic metals via drinking water consumption were estimated to be 6.1 × 10(-7), 2.1 × 10(-8), and 2.5 × 10(-7) for As, Cd, and Cr, respectively; the median values of incremental lifetime for non-cancer risks were estimated to be 6.1 × 10(-6), 4.4 × 10(-5), and 2.2 × 10(-5) for Hg, Pb, and Sb, respectively. The median value of total incremental lifetime health risk induced by the six non-essential trace elements for the population was 3.5 × 10(-5), indicating that the potential health risks from non-carcinogenic trace elements in drinking water also require some attention. Sensitivity analysis indicates that the most important factor for health risk assessment should be the levels of heavy metal in drinking water.

Medicinal insects have been widely used to cure human diseases for ages. Nevertheless, knowledge about the toxic chemicals accumulated in medicinal insects and their effects on human health was insufficient. In the present study, sixteen priority polycyclic aromatic hydrocarbons (PAHs) and nine halogenated PAHs (HPAHs) were determined in farmed medicinal cockroaches to address this issue. Total concentrations of PAHs in young nymphs, old nymphs, and adults ranged from 162 to 1025, 252 to 967, and 267 to 1168 ng/g, respectively. Levels of the sum of HPAHs varied from 0.84 to 9.17, 1.86 to 5.21, and 1.01 to 8.60 ng/g for young nymphs, old nymphs, and adults, respectively. The daily intake and excess cancer risk of PAHs and HPAHs were calculated for people who take cockroach-related drugs. Our results indicated that females and children have slightly higher exposure levels from the perspectives of gender and age, respectively. The estimated excess cancer risk of PAHs and HPAHs were both lower than the priority risk level (10(-4)), indicating a low potential carcinogenic risk with the medicinal cockroach consumption., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Size distribution of particles in part dictates the environmental behavior of particle-bound organic pollutants in the atmosphere. The present study was conducted to examine the potential mechanisms responsible for the distribution of organic pollutants in size fractionated particles and their environmental implications, using an e-waste recycling zone in South China as a case study. Size-fractionated atmospheric particles were collected at the heights of 1.5, 5, and 20 m near two residential apartments and analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of particle-bound ΣPBDE (sum of 18 PBDE congeners) were significantly greater at 5 and 20 m than those at 1.5 m. The size-fractionated distributions of airborne ΣPBDE displayed trimodal peaks in 0.10–0.18, 1.8–3.2, and 10–18 μm at 1.5 m but only an unimodal peak in 1.0–1.8 μm at 20 m height. Emission sources, resuspension of dust and soil, and volatility of PBDEs were important factors influencing the size distribution of particle-bound PBDEs. The dry deposition fluxes of particle-bound PBDE estimated from the measured data in the present study were approximately twice the estimated wet deposition fluxes, with a total deposition flux of 3000 ng m(–2) d(–1). The relative contributions of particles to dry and wet deposition fluxes were also size-dependent, e.g., coarse (aerodynamic diameters (Dp) > 1.8 μm) and fine (Dp < 1.8 μm) particles dominated the dry and wet deposition fluxes of PBDEs, respectively.

A quantitative model was developed to predict the contributions of various pathways of taking up polybrominated diphenyl ethers (PBDEs) into leaves of three evergreen tree species, including soil-root-leaf pathway, soil-air-leaf pathway, and gaseous deposition. The contributions of soil-root-leaf pathway were negligible for PBDE accumulation in leaves. Soil-air-leaf pathway accounted for 16.3% and 3.8% of the total BDE-28 and BDE-47 levels in leaves, respectively; but for the PBDE congeners with log KAW≤-4 and log KOA>11, this pathway was ignorable. The contributions of gaseous deposition varied widely, accounting for 10%-50% for BDE-28, 100, 153, 154, and 183, 34%-96% for BDE-47, and <5% for BDE-209 of the measured concentrations in leaves of the three tree species. Therefore, direct atmosphere deposition without the influence of soil volatilization was a significant pathway for foliar uptake of BDE-47, 99, 100, 153, 154, and 183 on a background of low contaminated soil. For BDE-209, atmospheric particulate deposition dominates its foliar uptake., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Hexabromocyclododecane diastereoisomers (α, β, and γ-HBCD) and tetrabromobisphenol A (TBBPA) were investigated in air conditioning filter dust (designated as particulate phase of indoor air, PPIA) collected from an office building in Shenzhen, China in 2009. Concentrations of ΣHBCD (sum of α-, β-, and γ-HBCD) ranged from 652 to 122, 973 ng/g in PPIA. Generally, γ-HBCD was the most abundant diastereomer. Concentrations of TBBPA ranged from 30 to 59, 140 ng/g in PPIA. According to our results, approximate 61.9 pg/kg body weight/day (pg/kg/d) PM2.5 bound ΣHBCD can be inhaled deep into the lungs and 31.3 pg/kg/d PM10 bound ΣHBCD tends to be deposited in the upper parts of the respiratory system, and those values of TBBPA were 28.7 pg/kg/d and 14.5 pg/kg/d for the lower and upper respiratory tracts, respectively. The average intakes of ΣHBCD via dust inhalation and ingestion were 37.92 pg/kg/d and 2, 079 pg/kg/d for adults, and those data of TBBPA were 17.62 pg/kg/d and 966.2 pg/kg/d, respectively. Our research found that exposure via indoor dust inhalation and ingestion contributed more than dietary pathway. Sensitivity analysis result suggests that the concentration of HBCD and TBBPA is the most significant parameter governing estimated results, and the other parameters, such as body weight and inhalation rate, do not affect the outcome much., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Paper receipt has been documented as one major source of bisphenol A (BPA) for human exposure but little has been done by researchers to elaborate the potential health risk caused by handling paper receipt up to date. In the present study, BPA was analyzed in 42 supermarket receipts collected from Shenzhen, China. BPA was detected in all samples at concentrations ranging from 2.58 to 14.7mgg(-1). In most cases, the total amount of BPA on the receipt was at least one thousand times the amount found in the epoxy lining of a food can, another controversial use of the chemical. The estimated daily intakes (EDI) of BPA via handling of supermarket receipt ranged from 2 to 347μgday(-1) (mean, 40.4μgday(-1)) for a supermarket cashier and from 0.24 to 3.98μgday(-1) (mean, 0.69μgday(-1)) for general population. Based on the cumulative probability distribution of the calculated daily exposure to BPA via handling supermarket receipt, the EDI at the 0.1th and 1th percentile for supermarket cashier and general population, were already larger than 100ng (kgbw)(-1)day(-1), while at the 0.2th and 71th percentile, the EDI for both populations reached 1000ng (kgbw)(-1)day(-1). Considering the adverse endocrine disruptive effects of BPA and the dosage exposure level (from tens to hundreds ng (kgbw)(-1)day(-1)), human exposure to BPA in Shenzhen deserves more attention. Sensitivity analysis result showed that the handling time and frequency of supermarket receipts are the most important variables that contributed to most of the total variance of exposure., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Fourteen polybrominated diphenyl ethers (PBDEs) were measured in surface sediments collected from an urban watershed in a rapidly urbanizing region, Shenzhen, China. BDE209 was the predominant congener of PBDEs detected in surface sediments, which was consistent with the fact that technical deca-BDE mixtures are the dominant PBDE formulation used in China, especially the Pearl River Delta. A positive association between sediment PBDEs and catchment degree of urbanization suggested that the rapid urbanization process may be affecting the PBDEs levels in surface sediments. Similar to the "urban heat island effect", an "urban pollution island effect" was observed in the present study. These results indicated that PBDEs can be used as potential indicator chemicals of catchment's urbanization process in the present region., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Thirty four sampling sites along an elevation transect in the Tibetan Plateau region were chosen. Soil cores were divided into several layers and a total of 175 horizon soil samples were collected from July to September 2011, for determination of polycyclic aromatic hydrocarbons (PAHs). The measured PAHs concentration in surface soils was 56.26 ± 45.84 ng g(-1), and the low molecular weight PAHs (2-3 rings) predominated, accounting for 48% and 35%. We analyzed the spatial (altitudinal and vertical) distribution of PAHs in soil, and explored the influence of related environmental factors. Total organic carbon (TOC) showed a controlling influence on the distribution of PAHs. PAH concentrations declined with soil depth, and the composition patterns of PAHs along soil depth indicated that the heavy PAHs tended to remain in the upper layers (0-10 cm), while the light fractions were transported downward more easily. PAHs inventories (8.77-57.92 mg m(-2)) for soil cores increased with mean annual precipitation, while the topsoil concentrations decreased with it. This implies that an increase in precipitation could transfer more PAHs from the atmosphere to the soil and further transport PAHs from the topsoil to deeper layers.

This work extends previous studies on the occurrence of persistent halogenated compounds in consumer seafood from South China. Residual levels of 16 U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) and 9 halogenated PAHs (HPAHs) were determined in three kinds of seafood products collected from 11 coastal cities in South China from June to October 2005. The results indicated that PAH components were low but detectable in a large number of seafood samples under investigation. The benzo(a)pyrene (BaP)-like TEQ concentrations of HPAHs were higher than those of PAHs for all three kinds of seafood. The relative contributions of each seafood group to the total estimated daily intake of PAHs and HPAHs were also analyzed. Shellfish contributed the most to the total exposure for all subgroups, followed by shrimp. Overall, the excess cancer risks (ECRs) induced by HPAHs were much greater than the risks posed by PAHs. Both ECRs for PAHs and HPAHs were far below 10(-4), showing no significant cancer risk via seafood consumption for people in South China. Sensitivity analysis results show the oral cancer slope factor of BaP is the most influential variable that contributed most to the total variance of risk for all subgroups.