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Organophosphate esters (OPEs) are widespread in the environment, with high persistence and toxicity. However, the underlying mechanisms of anaerobic microbial degradation of OPEs remain elusive in the field environment. In this study, the natural attenuation mechanisms of tributyl phosphate (TnBP) by indigenous anaerobic microorganisms in soils were investigated by using compound-specific stable isotope analysis (CSIA) and characterization of microbial communities. The results indicated that dibutyl phosphate (DnBP) was the major degradation product of TnBP. Significant carbon isotope fractionation was observed for TnBP during the anaerobic microbial degradation, and the carbon isotope enrichment factor (ε C) was determined to be −2.71 ± 0.13‰. Unlike aerobic degradation with P-O bond cleavage, C-O bond cleavage was verified as the mode to removal a butyl side chain for TnBP to generate DnBP during the anaerobic microbial degradation. Microbial community analysis indicated that Sphingomonans , Nocardioides and Streptomyces were the important contributors to microbial degradation of TnBP in anoxic soils. TnBP altered microbial metabolic functions in anoxic soils, mainly enhancing the biosynthesis of ansamycins, ketone bodies and amino acids, and flagellar assembly, which promoted microbial degradation of TnBP. This study provided a better method to characterize the chemical bond cleavage mode and effect of OPEs on microbial communities, which was a prerequisite for the bioremediation of OPE pollution in soils. [Display omitted] • Natural attenuation of TnBP by indigenous microbes were disclosed in anoxic soils. • Anaerobic microbial degradation led to stable carbon isotope fractionation of TnBP. • Removal of a butyl side chain to generate DnBP was degradation pathway of TnBP. • Cleavage of C-O rather than P-O was key mode to removal a butyl side chain for TnBP. • Sphingomonas and Nocardioides played key roles on microbial degradation of TnBP. [ABSTRACT FROM AUTHOR]

[Display omitted] • Jurassic mineralized Tongshan porphyries were derived from Neoproterozoic juvenile crust. • Difference in the subduction depth of the slab generated heterogeneous juvenile crust. • Fertile porphyries have high whole-rock Th/Yb and zircon Ce/Ce* and Ce/Nd ratios. The Qin–Hang suture belt in South China formed during the Neoproterozoic amalgamation between the Cathaysia and Yangtze blocks. There are several Jurassic porphyry–skarn Cu deposits in this region, and the factors controlling the mineralization potential remain unclear. This study reports geochemical data for the Tongshan skarn deposit and zircon trace element data for five porphyry- or skarn-type Cu deposits in this region, in order to identify geochemical indexes for the mineralization potential of the ore-related intrusions. A garnet U–Pb age (170 Ma) for the Tongshan skarn indicates that Cu mineralization occurred in the Middle Jurassic, which is consistent with the zircon U–Pb ages (173 Ma–171 Ma) of the host granodiorite porphyries. Granodiorite porphyry samples from the Tongshan deposit have moderately high SiO 2 contents (64.4–65.0 wt%), low MgO contents (1.39–1.47 wt%), and high (La/Yb) N ratios (14.7–16.8), typical of low-Mg adakitic rocks. The whole-rock geochemistry, bulk Earth-like ε Nd (t) values (–1.5 to –1.6) and positive zircon ε Hf (t) values (+2.7 to +6.0), corresponding to two-stage Hf model ages of 1014–832 Ma, suggest the porphyries were derived from thickened juvenile lower crust initially generated during Neoproterozoic amalgamation. In addition, the porphyry samples have arc-like geochemical characteristics (Nb–Ta–Ti depletion), low Th/Yb ratios (average = 4.7), high Ba/Th ratios (average = 346), zircon Eu/Eu* values (average = 0.71) and 10000×(Eu/Eu*)/Y values (average = 6.80), and moderate zircon Ce/Ce* values (average = 705) and Ce/Nd ratios (average = 17.1). These features demonstrate that the parental magmas of the porphyries were formed by melting of a mantle wedge. That had been metasomatized by moderately oxidized slab-derived fluid near a Neoproterozoic subduction zone. Previous studies suggest porphyries from large to giant deposit (e.g., Dexing and Yinshan) have similar two-stage Hf model ages and were derived from Neoproterozoic juvenile crust. But these porphyries have higher whole–rock Th/Yb ratios and zircon Ce/Ce* and Ce/Nd values than those of intrusions from medium-sized deposits (e.g., Tongshan, Chuankeng and Jiande). This indicates that the magma source of the former may have been distant from the trench in the Neoproterozoic, and formed by melting of a mantle wedge that had been metasomatized by highly oxidized slab-derived melt. Our results and previously published data indicate that the Neoproterozoic two-stage Hf model ages of the intrusions are positive indicators of Jurassic Cu mineralization, and granitoids with relatively high Th/Yb ratios and zircon Ce/Ce* and Ce/Nd values likely have more potential to form large to giant Cu deposits. [ABSTRACT FROM AUTHOR]

With the increasing industrialization and urbanization, the ecological environment is suffering from severe deterioration in Liaohe coastal wetland, and petroleum spill is one of the pollution sources. Suaeda salsa (L.) Pall (S. salsa), one of the predominant plants in Liaohe coastal wetland, is facing the increasing degradation. Terpenes are a class of inherent compounds in plants, and play key role in maintain the growth of plants. However, the environmental stress on the terpene metabolism remained unclear in the plants. In the present study, the influence of petroleum spill on terpene metabolism in S. salsa was systematically investigated by analysis of concentrations, compositions and stable carbon isotope. Under the stress of petroleum spill, terpene concentrations showed the decreasing trend, indicating the inhibition effect of petroleum spill on terpene synthesis in S. salsa. The proportions of Sabinene and A-humulene showed the obviously increased with the influence of petroleum spill, implying that these congeners were more sensitive to petroleum spills. The significant changes in stable carbon isotope compositions were observed for Borneol, Dl-menthol, A-humulene and (-) -@-bisabolol, with the enrichment in heavier isotopes in residual fractions. This result indicated that the heavier 13C was preferentially fixed on terpene by S. salsa under the petroleum stress. The similar change trends along the incubation time was observed for A-humulene and (-) - trans caryophyllene, which might imply that A-humulene was one of the products of (-) - trans caryophyllene in S. salsa. Overall, the findings of present study verified the influence of petroleum spill on terpene metabolism in S. salsa , and were meaningful for protecting the plants in the petroleum-pollution wetlands. [Display omitted] • Terpene contents in S. salsa decreased with increasing petroleum dose. • Proportions of monoterpenes increased under influence of petroleum spill. • Stable carbon isotope analysis confirmed effect of petroleum on terpene metabolism. • A-humulene was evidenced to be one product of (-) - trans caryophyllene in S. salsa. [ABSTRACT FROM AUTHOR]

Strict restriction on legacy per - and polyfluoroalkyl substances (PFASs) has caused a dramatic increase in production and usage of emerging PFASs over the last decades. However, the environmental behaviors of emerging PFASs is largely unknown in Daling River, Northern China. In this study, the potential sources, sediment-water partitioning and substitution trends of PFASs were investigated in overlying water and sediments from Daling River and its estuary. Perfluorooctane sulfonate and 6:2 fluorotelomer sulfonic acid were major compounds, and sodium p -perfluorous nonenoxybenzene sulfonate was first detected. Firefighting foam manufacturing and fluoropolymer production were the main sources of PFASs. Compared to legacy PFASs (C 8), the emerging PFASs (C 6 - C 9) were more incline to distribute into overlying water. Substitution trends indicated 6:2 fluorotelomer sulfonic acid and hexafluoropropylene oxide trimer acid as the important alternatives of perfluorooctane sulfonate and perfluorooctanoic acid, respectively. The results were meaningful for understanding the environmental behaviors of emerging PFASs. • OBS was first detected in water and sediments from Daling River and its estuary. • 6:2 FTSA and PFOS were predominant congeners in both water and sediments. • Emerging PFASs were more inclined to accumulated in water than legacy PFASs. • K ow played the key role in the sediment-water partitioning of PFASs. • 6:2 FTSA and HFPO-DA were the main alternatives of PFOS and PFOA, respectively. [ABSTRACT FROM AUTHOR]

Abstract As a developed city in North China, Tsingtao is believed to be suffering from the pollution of polybrominated diphenyl ethers (PBDEs) due to the rapid industrialization and urbanization in recent years. In this work, 8 PBDE congeners were detected in sediments from Moshui River, Tsingtao. BDE-209 and sum of 7 low brominated PBDE congeners (∑ 7 PBDEs, excluding BDE-209) ranged from 10.2 × 10−3 to 237 × 10−3 mg kg−1 and from 1.62 × 10−3 to 23.1 × 10−3 mg kg−1 d.w., respectively. PBDE concentrations decreased in the order of midstream > downstream > upstream, attributing to the discrepancies in anthropogenic activities among these areas. Principal component analysis coupled with multiple linear regression (PCA-MLR) revealed that 24.4% of PBDEs were derived from surface runoff of contaminated soils, 58.2% from direct discharge of local sources and 17.4% from atmospheric deposition. The probabilistic health risk assessment of PBDEs was performed by using Monte Carlo simulation. The carcinogenic and non-carcinogenic risks based on total PBDEs were low for children and teens, whilst severe for adults. However, based on bioaccessible PBDEs (in vitro gastrointestinal model), there was no obvious health risk for the three age groups. To the best of our knowledge, the present study was the first attempt to assess the health risk by using bioaccessible PBDEs in sediments. Graphical abstract Image 1 Highlights • High PBDE levels were detected in sediments from Moshui River, Tsingtao. • Environmental debromination of high brominated congeners occurred in Moshui River. • PBDEs came from local sources, surface runoff and atmospheric deposition. • Health risk assessment was inconsistent between total and bioaccessible PBDEs. This study was the first attempt to assess the health risk by using bioaccessible PBDEs in sediments via an in vitro gastrointestinal model. [ABSTRACT FROM AUTHOR]

Liaohe coastal wetland has experienced severe degradation of Suaeda salsa (L.) Pall (S. salsa) in recent years. However, the impact of exogenous betaine (GB) on S. salsa growth remains unclear. Therefore, we conducted a natural simulated cultivation in soils of coastal wetland to investigate the effects of GB on S. salsa growth. The results showed that GB increased the height and weight of S. salsa , and meanwhile stimulated the synthesis of endogenous betaine and amino acids, increased soluble sugars and elevated the activity of Na+, K+-ATPase (enhancing osmotic stability). In addition, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased, and malondialdehyde (MDA) and H 2 O 2 decreased correspondingly, thereby improving the antioxidant capacity. Overall, GB application significantly alleviated salt stress and effectively promoted S. salsa growth. This study first indicated the important role of GB in influencing S. salsa growth, offering potential strategies for remediation in coastal wetlands. • GB promoted the synthesis of endogenous betaine in S. salsa. • GB can promote plant growth. • GB enhanced the osmotic stability of S. salsa. • The exogenous application of GB can significantly alleviate salt stress. [ABSTRACT FROM AUTHOR]

As an emerging halogenated organic contaminant, Dechlorane Plus (DP) was scarcely reported in marine environments, especially in China. In this work, 35 surface sediments and a sediment core were collected across the Southern Yellow Sea (SYS) to comprehensively explore the spatio-temporal distribution and possible migration pathway of DP. DP concentrations ranged from 14.3 to 245.5 pg/g dry weight in the surface sediments, displaying a seaward increasing trend with the high levels in the central mud zone. This spatial distribution pattern was ascribed to that fine particles with the elevated DP levels were preferentially transported to the central mud zone under hydrodynamic forcing and/or via long-range atmospheric transportation and deposition. DP concentrations in sediment core gradually increased from the mid-1950s to present, which corresponded well with the historical production and usage of DP, as well as the economic development in China. Significantly positive correlation between DP and total organic carbon (TOC) in both surface sediments and sediment core indicated TOC-dependent natural deposition of DP in the SYS. We used multiple biomarkers, for the first time, to explore the potential effects of terrestrial and marine organic matters (TOM and MOM) on DP deposition. The results showed that competition may occur between TOM and MOM for DP adsorption, and MOM was the predominant contributor in controlling DP deposition in the marine sediments from the SYS. [ABSTRACT FROM AUTHOR]

As the widely used flame retardant, polybrominated diphenyl ethers (PBDEs) have been ubiquitously detected in wetland sediments. Microbial degradation is the importantly natural attenuation process for PBDEs in sediments. In this study, the microbial degradation of PBDEs and inherent alternation of microbial communities were explored in anaerobic sediments from coastal wetland, North China. BDE-47 and BDE-153 could be degraded by the indigenous microbes, with biodegradation following pseudo-first-order kinetic. In sediments, the major genera for BDE-47 and BDE-153 degradation were Paeisporosarcina and Gp7 , respectively, in single exposure. However, Marinobacte r was dominant genera in the combined exposure to BDE-47 and BDE-153, and competition against Marinobacter existed between BDE-47 and BDE-153 degradation. Analysis of bacterial metabolic function indicated that membrane transport, amino acid and carbohydrate metabolism were included in degradation. This study provides the systematic characterization of the sediment microbial community structure and function associated anaerobic microbial degradation of PBDEs in coastal wetland. [Display omitted] • Biodegradation of BDE-47 and BDE-153 followed pseudo-first-order kinetic. • Paeisporosarcina and Gp7 was dominated in single exposure to BDE-47 and BDE-153. • Marinobacter was dominant bacteria in combined exposure to BDE-47 and BDE-153. • Membrane transport, amino acid and carbohydrate metabolism included in degradation. [ABSTRACT FROM AUTHOR]

Sediment samples ( n = 20) were collected from Yangtze River Estuary (YRE) and the adjacent East China Sea (ECS) inner shelf to explore spatial and temporal distributions, environmental fate, sources and potential health risk of polybrominated diphenyl ethers (PBDEs). Concentrations of BDE-209 and total 7 PBDEs (without BDE-209; ∑ 7 PBDEs) ranged from 62.3 to 1758 pg g −1 and from 36.9 to 233.6 pg g −1 dry weight, respectively; both of the highest values occurred near the city of Wenzhou. Concentrations of BDE-209 and ∑ 7 PBDEs both indicated a decreasing trend from inshore areas toward outer shelf. Significantly positive linear correlations were only observed between logBDE-183 concentrations and TOC/grain size ( r 2 = 0.6734 and 0.5977 for TOC and grain size, respectively) as well as BDE-209 and TOC/grain size ( r 2 = 0.4137 and 0.5332 for TOC and grain size, respectively) in the north of 28 ° N, indicating that YR had significant influence on the distribution of higher brominated congeners only in the north part. Depth profiles of PBDEs in a sediment core P01 ( n = 1, m = 11) collected from YRE showed that the input of BDE-209 gradually increased from 1930 to 2010, while the levels of ∑ 7 PBDEs peaked in 1986 and obviously decreased in recent years. Partial Least-Squares Regression (PLSR) revealed that PBDEs in the coastal ECS were mainly from direct discharge of local anthropogenic activities (80.7%), followed by surface runoff of contaminated soils (15.1%), microbial degradation after sedimentation (2.6%) and photodegradation during atmospheric transportation (1.6%). The cancer risk of human exposure to BDE-209 at the 95% confidence level was 3.09 × 10 −7 , 1.67 × 10 −7 and 8.86 × 10 −7 for children, teens and adults, respectively, significantly lower than the threshold level (10 −6 ). Hazard index (HI) calculated for non-cancer risk was also far less than 1 for the three groups, suggesting no non-cancer risk. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were analyzed to assess the environmental quality in the surface sediments from Bohai Sea (BS), China. Concentrations of ∑ 37 PCBs, ∑ 7 PBDEs and BDE-209 were 0.157–1.699, 0.100–0.479 and 0.464–6.438 ng/g (dry weight), respectively. All of these concentrations decreased generally from the coastal areas towards the outer sea, indicating intensive influences of anthropogenic activities. Principal component analysis (PCA) coupled with multiple linear regression (MLR) revealed that 82.1% of the PCBs in BS came from direct discharge of local anthropogenic activities, 16.3% from surface runoff of contaminated soils and 1.6% from atmospheric deposition. PBDEs were mainly derived from the usage and dismantling of products containing commercial Penta-, Octa- and Deca-BDEs. According to sediment quality guidelines (SQGs), the ecological risks of PCBs could be negligible, and penta- and deca-BDE homologs might be the major contributors of ecological risks in the BS sediments. [ABSTRACT FROM AUTHOR]

A complex relationship exists between copper stress and the accumulation and release of domoic acid (DA) in toxin-producing Pseudo-nitzschia cells. To clarify the changes and role of DA in this process, we exposed the toxin-producing P. multiseries and the non-toxin-producing P. pungens to copper stress (5 and 9 μM) for 96 h. Results showed that P. multiseries grew better than P. pungens under the two aforementioned copper concentrations. DA content in the cells of P. multiseries increased with increased copper stress, and the dissolved DA in the medium under the 9 μM copper treatment increased. DA addition at a 9 μM copper concentration reduced the copper content in P. multiseries cells and cell walls, but did not change the free copper ion content in culture medium. Adding DA to the medium reduced the malondialdehyde (MDA) content in the cells of P. multiseries under copper stress, DA addition also reduced the activities of catalase (CAT) and superoxide dismutase (SOD) at 5 μM Cu, and the activity of peroxidase (POD) at 9 μM Cu. This suggests that DA may not alleviate copper stress by improving the antioxidant defense system of algal cells, nor can it be complexed with copper ions in the medium to alleviate copper stress. Furthermore, the reactive oxygen species (ROS) scavenger N-tert-butyl-α-phenylnitrone (BPN) was used to study the DA accumulated in cells. The BPN addition significantly reduced the accumulation of DA in the cells under copper stress, suggesting that DA content in cells was closely related to ROS. Moreover, further experiments demonstrated that DA addition can improve the growth of P. multiseries under hydrogen peroxide stress. Our results indicate that DA alleviates P. multiseries oxidative damage when expose to copper stress. Image 1 • Higher copper concentrations and longer exposure times resulted in higher intracellular DA contents in the P. multiseries. • Addition of domoic acid can relieve copper stress and hydrogen peroxide stress in the P. multiseries. • Addition of domoic acid under copper stress did not improve enzyme activity of P.multiseries. • Addition of domoic acid under copper stress did not reduce free copper ions in culture medium. • Domoic acid may alleviate the oxidative damage of cells under copper stress. [ABSTRACT FROM AUTHOR]

Symbiosis of marine algae is inevitable in the marine environment, and species may occur interaction on the growth. In this study, the macroalgae Ulva pertusa and marine microalgae Heterosigma akashiwo were selected as target species to study the interaction mechanism between them. After the 8 days of co-cultivation, the inhibition on growth was observed for both of U. pertusa and H. akashiwo. Eight fatty acids in U. pertusa was detected, with the significant decrease in contents of polyunsaturated fatty acids (PUFAs) especially for C18:2, C18:3n-3 and C18:3n-6. Twelve fatty acids in H. akashiwo was detected, with the significant change for PUFAs. PUFA concentrations in the co-culture group were less than those in the mono-culture. Meanwhile the principal component analysis was conducted to insight into the interaction between U. pertusa and H. akashiwo by fatty acids content and carbon stable isotope ratio of fatty acids (δ13C FAs). Fatty acid content could not distinguish mono and co-culture. However, δ13C FAs could distinguish not only the culture time of algae, but also the living environment of algae. In addition, this study combined fatty acids content and δ13C FAs to explore the release of fatty acids by algae into the seawater. The C18:3n-3 was identified as the allelochemical released by U. pertusa to inhibit the growth of H. akashiwo. The ratio of δ13C FAs in seawater decreased. This study provides a theoretical basis for the symbiosis of marine algae, and a new method of compound-specific stable carbon isotopes was used to better explore the metabolism of fatty acids in algae. ga1 • U. Pertusa and H. akashiwo were inhibited growth by each other. • The PUFAs of U. Pertusa and H. akashiwo were significantly decreased in co-culture. • The δ13C FAs could a better indicator to distinguish the influence of external stress on algae. • The δ13C FAs secreted by algae into seawater were more negative than the δ13C FAs in algae. [ABSTRACT FROM AUTHOR]

It is highly likely that the toxicity of water accommodated fractions (WAF) will influence marine microalgae, and consequently lead to potential risk for the marine ecological environment. However, it was often neglected whether WAF can influence the transformation of relative compounds in organisms. The metabolism of amino acids (AAs) can be used to track physiological changes in microalgae because amino acids are the basis of proteins and enzymes. In this study, using marine Chlorophyta Platymonas helgolandica as the test organism, the effects of different concentrations of WAF on AA compositions and stable carbon isotope ratios (δ 13C) of individual AAs of Platymonas helgolandica were investigated. The results showed that the WAF of #180 fuel oil had an obvious suppressing effect on the growth and chlorophyll a content of microalgae. The growth inhibitory rate at 96 h was 80.66% at a WAF concentration of 0.50 mg L−1 compared with the control. Furthermore, seven among the 16 AAs, including alanine, cysteine, proline, aspartic acid, lysine, histidine and tyrosine, had relatively high abundance. Under the glycolysis pathway, the cysteine abundance was higher than control, meaning that the biosynthesized pathway of alanine through cysteine as a precursor could be damaged. Phosphoenolpyruvate (PEP) was an important synthesis precursor of alanine (leucine) and aromatic AA family (Phenylalanine and tyrosine), and played an important role in δ 13C AAs fractionation under the WAF stress. Under the TCA pathway, to protect cell metabolism activities under WAF stress, the δ 13C value of threonine and proline abundance in microalgae with the increase in WAF stress. Therefore, δ 13C AAs fractionation can be used as a novel method for toxicity evaluation of WAF on future. Image 1 • WAF increases Pro and Tyr abundance in algae. • δ 13C Thre increased with the WAF to maintain cell metabolism activities. • δ 13C His value was higher in experiment than control groups. • PEP played an important role in δ 13C fractionation of Leu, Phe and Tyr under WAF. This study systematically investigated the δ 13C AAs variations in microalgae under the acute toxicity of WAF, and revealed the selection mechanism of AAs metabolic pathways. [ABSTRACT FROM AUTHOR]

Effect of water accommodated fractions (WAF) of #180 fuel oil on fixed carbon and nitrogen in microalgae was studied by stable isotopes. Platymonas helgolandi ca , Heterosigma akashiwo and Nitzschia closterium were exposed to five WAF concentrations for 96 h. The δ 13C value of microalgae was significantly lower than that of the control group, indicated that carbon was limited in the WAF concentrations. The δ 13C value of microalgae appeared peak valley at 48 h in control group, corresponding to the enhanced capacity in carbon fixation during microalgae photosynthesis. The physiological acclimation capacity of microalgae was revealed by the occurrence time when the δ13C value was in peak valley, and thus the physiological acclimation capacity of microalgae decreased in the order of Nitzschia closterium > Heterosigma akashiwo > Platymonas helgolandica. Principal component analysis (PCA) were applied to the δ13C value in order to verify the "hormesis" phenomenon in microalgae. The δ13C value could discriminate between stimulatory effects at low doses and inhibitory effects at high doses. In addition, the present study also investigated the effect of the nitrogen on microalgae growth. Because microalgae could still absorb the NO 3 –N and release of NO 2 –N and NH 4 –N in present study, the nitrogen cycle in microalgae was in the equilibrium status. The δ 15N value in microalgae exhibited no obvious change with the increasing of WAF concentrations at the same time. However, due to the enrichment of nitrogen, the δ 15N value first increased gradually with the time and finally was stable. Overall, the fractionation of carbon and nitrogen stable isotopes illustrated that the effect of carbon on the growth of microalgae was more prominent than nitrogen. Stable isotopes was used to investigate the influence of WAF on fixed carbon and nitrogen in microalgae growth, providing a fundamental theoretical guidance for risk assessment of marine ecological environment. • Toxic effects of oil spill on microalgae were explored by using δ 13C and δ 15N. • Algae δ 13C indicated that carbon was limited in the WAF concentrations. • Algae δ 13C verify the "hormesis" phenomenon. • The NO 3 –N of three microalgae decreased with time under the different WAF. • The algae δ 15N illustrated the nitrogen cycle was in the equilibrium status. [ABSTRACT FROM AUTHOR]

Microbial degradation is an important pathway for the attenuation of polybrominated diphenyl ethers (PBDEs) in natural soils. In this study, the compound-specific stable isotope analysis (CSIA) was applied to characterize microbial degradation of BDE-153, one of the prevailing and toxic PBDE congeners, in natural wetland soils. During the 45-day incubation, the residual percentages of BDE-153 decreased to 67.9% and 73.6% in non-sterilized soils spiked with 1.0 and 5.0 μ g/g, respectively, which were both much lower than those in sterilized soils (96.0% and 97.2%). This result indicated that microbial degradation could accelerate BDE-153 elimination in wetland soils. Meanwhile, the significant carbon isotope fractionation was observed in non-sterilized soils, with δ 13C of BDE-153 shifting from −29.4‰ to −26.7‰ for 1.0 μ g/g and to −27.2‰ for 5.0 μ g/g, respectively, whilst not in sterilized soils. This phenomenon indicated microbial degradation could induce stable carbon isotope fractionation of BDE-153. The carbon isotope enrichment factor (ε c) for BDE-153 microbial degradation was first determined as −7.58‰, which could be used to assess the microbial degradation and bioavailability of BDE-153 in wetland soils. Based on δ 13C and ε c , the new methods were developed to dynamically and quantitatively estimate degradation degree and bioavailability of BDE-153 during degradation process, respectively, which could exclude interference of physical processes. This work revealed that CSIA was a promising method to investigate in situ microbial degradation of PBDEs in field studies. Image 1 • Microbial degradation of BDE-153 followed first-order kinetic model in soils. • Microbial degradation induced stable carbon isotope fractionation of BDE-153. • Carbon isotope enrichment factor of BDE-153 was −7.58‰. • CSIA was used to dynamically and quantitatively estimate BD and BA of BDE-153. [ABSTRACT FROM AUTHOR]

Organophosphate esters (OPEs) in indoor dust were closely related to human health. However, OPE contamination in college library dust remained unknown at present. In this study, OPEs were first investigated in 78 indoor dust samples and 26 field blanks of 26 college libraries from 13 prefecture-level cities across China between October and December 2017. The total OPEs fell in the range of 8706–34872 ng/g, and were dominated by tris(2-chloroisopropyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP) and tris(2-butoxyethyl) phosphate (TBOEP). OPEs exhibited geography-specific distributions, with high levels in Beijing, Shanghai and Guangzhou. OPEs significantly correlated with population density and gross domestic product (p < 0.01), indicating the distinct effect of these two indicators on OPE pollution. Analysis of pollution source indicated volatilization and abrasion as main emission pathways of OPEs from OPEs-added products to dust. The daily exposure doses (DEDs) of OPEs via dust ingestion, inhalation and dermal contact were similar for male and female students, ranging from 1.35 to 5.92 ng/kg-bw/day during study time in libraries (25% of day). High DEDs were found in Beijing, shanghai and Guangzhou, indicating high exposure risk of OPEs to college students in large cities. The non-carcinogenic and carcinogenic risks of OPEs to college students were quantitatively evaluated based on the oral reference dose and cancer slope factor of OPEs recently updated by USEPA, and all much lower than the threshold risk values. However, the potential risk may occur if exposure to OPEs is high in other microenvironments over remaining hours of the day. Image 1 • OPEs showed geography-specific distribution with high levels in Beijing and Shanghai. • Gross domestic product and population density influenced OPE contamination. • Health risks of OPEs in library dust were low for students in studied colleges. [ABSTRACT FROM AUTHOR]