Polybrominated dibenzo-p-dioxins/furans and their chlorinated analogues in sediments from a historical hotspot for both brominated flame retardants and organochlorine pesticides.

Polybrominated dibenzo-p-dioxin/furans (PBDD/Fs) and polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs) in the environment are closely related to their precursors, brominated flame retardants (BFRs) and organochlorine pesticides (OCPs). However, their change trends following the regulation of BFRs and OCPs remain incompletely characterized. Here, we examined PBDD/Fs and PCDD/Fs in sediments from a historical hotspot for both BFRs and OCPs, namely the Pearl River Delta (PRD), China. PBDD/Fs showed ubiquity in these samples but significantly lower concentrations than PCDD/Fs. Spatially, the occurrence of PBDD/Fs was positively correlated with local development levels and sediments from highly urbanized/industrialized areas showed higher and increasing PBDD/F concentrations. Polybrominated diphenyl ether (PBDE)-related products/industries were the greatest PBDD/F contributors to the PRD, followed by bromo-phenol/benzene-related products/industries. PCDD/Fs in PRD sediments showed significant positive correlations with local grain planting area, yield, and pesticide consumption. The historical use of pentachlorophenol (PCP)/PCP-Na and biomass open-burning were the leading PCDD/F sources of the PRD agricultural/rural areas, where the concentrations and toxic equivalent quantities (TEQs) of PCDD/Fs in sediments changed very little over the past decade. Anthropogenic thermal processes involved in metallurgy, waste incineration, and vehicles were the greatest PCDD/F contributors in the PRD urban/industrial areas, where the PCDD/F concentrations in sediments almost doubled over the last decade. This finding indicates the increasing PCDD/F contributions of industrial and municipal activities in the PRD, despite the implementation of strict emission standards. Over sixty percent of the samples showed TEQs that surpassed the low-risk threshold specified for mammalian life by the U.S. EPA (2.5 pg TEQ g-1) and warrant continuous attention.

Large contribution of fossil-derived components to aqueous secondary organic aerosols in China.

Incomplete understanding of the sources of secondary organic aerosol (SOA) leads to large uncertainty in both air quality management and in climate change assessment. Chemical reactions occurring in the atmospheric aqueous phase represent an important source of SOA mass, yet, the effects of anthropogenic emissions on the aqueous SOA (aqSOA) are not well constrained. Here we use compound-specific dual-carbon isotopic fingerprints (δ13C and Δ14C) of dominant aqSOA molecules, such as oxalic acid, to track the precursor sources and formation mechanisms of aqSOA. Substantial stable carbon isotope fractionation of aqSOA molecules provides robust evidence for extensive aqueous-phase processing. Contrary to the paradigm that these aqSOA compounds are largely biogenic, radiocarbon-based source apportionments show that fossil precursors produced over one-half of the aqSOA molecules. Large fractions of fossil-derived aqSOA contribute substantially to the total water-soluble organic aerosol load and hence impact projections of both air quality and anthropogenic radiative forcing. Our findings reveal the importance of fossil emissions for aqSOA with effects on climate and air quality.

New Insights into Human Biotransformation of BDE-209: Unique Occurrence of Metabolites of Ortho-Substituted Hydroxylated Higher Brominated Diphenyl Ethers in the Serum of e-Waste Dismantlers.

Extremely high levels of decabromodiphenyl ether (BDE-209) are frequently found in the serum of occupationally exposed groups, such as e-waste dismantlers and firefighters. However, the metabolism of BDE-209 in the human body is not adequately studied. In this study, 24 serum samples were collected from workers at a typical e-waste recycling workshop in Taizhou, Eastern China, and the occurrence and fate of these higher brominated diphenyl ethers (PBDEs) were investigated. The median concentration of the total PBDEs in the serum was 199 ng/g lipid weight (lw), ranging from 125 to 622 ng/g lw. Higher brominated octa- to deca-BDEs accounted for more than 80% of the total PBDEs. Three ortho-hydroxylated metabolites of PBDEs─6-OH-BDE196, 6-OH-BDE199, and 6'-OH-BDE206─were widely detected with a total concentration (median) of 92.7 ng/g lw. The concentrations of the three OH-PBDEs were significantly higher than their octa- and nona-PBDE homologues, even exceeding those of the total PBDEs in several samples, indicating that the formation of OH-PBDEs was a major metabolic pathway of the higher brominated PBDEs in occupationally exposed workers. An almost linear correlation between 6-OH-BDE196 and 6-OH-BDE199 (R = 0.971, P < 0.001) indicates that they might undergo a similar biotransformation pathway in the human body or may be derived from the same precursor. In addition, the occurrence of a series of penta- to hepta- ortho-substituted OH-PBDEs was preliminarily identified according to their unique "predioxin" mass spectral profiles by GC-ECNI-MS. Taken together, the tentative metabolic pathway for BDE-209 in e-waste dismantlers was proposed. The oxidative metabolism of BDE-209 was mainly observed at the ortho positions to form 6'-OH-BDE-206, which later underwent a consecutive loss of bromine atoms at the meta or para positions to generate other ortho-OH-PBDEs. Further studies are urgently needed to identify the chemical structures of these ortho-OH-PBDE metabolites, and perhaps more importantly to clarify the potentially toxic effects, along with their underlying molecular mechanisms.

PCDD/Fs and PBDD/Fs in sediments from the river encompassing Guiyu, a typical e-waste recycling zone of China.

Severe pollution of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and their brominated analogues (PBDD/Fs) was frequently reported for the waters located near unregulated e-waste recycling areas. However, the migrations of these high-level dioxins via waterways and their potential threats to the lower reaches were seldom investigated. In this study, we analyzed PCDD/Fs and PBDD/Fs in 27 surficial sediments collected from the Lian River encompassing the Guiyu, China e-waste recycling zone, and investigated their distributions, sources, migration behaviors and risks. Both PCDD/Fs and PBDD/Fs in these sediments exhibited a spatial trend of Guiyu > Guiyu downriver > Guiyu upriver, illustrating that the Guiyu e-waste recycling activities were the uppermost dioxin contributors in this watershed. Sediments from different Guiyu villages demonstrated big gaps in PCDD/F concentrations and congener compositions, and the reason was attributed to the diverse e-waste recycling activities practiced in these villages. Sediments near the e-waste open-burning areas demonstrated extremely high PCDD/F concentrations and unique PCDD/F profiles featured by low-chlorinated PCDFs (tetra- to hexa-), which is quite different from the OCDD-dominant PCDD/F profile found in most of the Lian River sediments. The geographical distributions of PCDD/F concentrations and profiles illustrate that the substantial amount of PCDD/Fs in Guiyu sediments were mainly retained in local and vicinal water bodies. The principal component analysis (PCA) results further confirm that the high-level PCDD/Fs in Guiyu sediments exhibited quite limited translocations downstream and therefore exerted little influences on the lower reaches. Pentachlorophenol use in history, ceramic industry and vehicle exhaust were diagnosed as the major PCDD/F sources for most sediments of the Lian River. Total toxicity equivalent quantities (TEQs) of 70% of the Lian River sediments surpassed the high-risk limit specified for mammalian life by the U.S.EPA (25 pg TEQ g-1), and most of these sediments were from Guiyu and its near downstream, which merit continuous attention and necessary remediation measures.

Influence of meteorological parameters and oxidizing capacity on characteristics of airborne particulate amines in an urban area of the Pearl River Delta, China.

Nine amine species in atmospheric particles during haze and low-pollution days with low and high relative humidity (RH) were analyzed in urban Guangzhou, China. The mean concentrations of total measured amines (Æ©amines) in fine particles were 208 ± 127, 63.7 ± 21.3, and 120 ± 20.1 ng m-3 during haze, low pollution-low RH (LP-LRH), and low pollution-high RH (LP-HRH) episodes, respectively. The dominant amine species were methylamine (MA), dimethylamine (DMA), diethylamine (DEA) and dibutylamine (DBA), which in total accounted for 82-91% of the Æ©amines during different pollution episodes. The contributions of Æ©amines-C to water-soluble organic carbon (WSOC) and Æ©amines-N to water-soluble organic nitrogen (WSON) were 1.52% and 2.49% during haze, 1.24% and 1.96% during LP-LRH, and 2.00 and 2.98% during LP-HRH days, respectively. The mass proportion of Æ©amines in fine particles was higher during LP-HRH periods (0.19%) than during haze and LP-LRH periods (0.16%). The mass proportion of DBA in Æ©amines increased from 7% during haze and LP-LRH episodes to 25% during LP-HRH episodes. Compared with other amines, DBA showed a stronger linear relationship with RH (r = 0.867, p < 0.01), which demonstrates its high sensitivity to high RH conditions. Meteorological parameters (including RH, the mixed layer depth, wind speed and temperature), the oxidizing capacity (ozone concentration), and gaseous pollutants (NOx and SO2) correlated with amines under different pollution conditions. Under high RH, acid-base reactions were the dominant pathway for the gas-to-particle distribution of amines in urban areas, while direct dissolution dominated in the background site. To our knowledge, this study is the first attempt to conduct in situ measurements of particulate amines during different pollution conditions in China, and further research is needed to in-depth understanding of the influence of amines on haze formation.

Polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) in soil around municipal solid waste incinerator: A comparison with polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs).

Polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) share similar toxicities and thermal origins, e.g., municipal solid waste incinerator (MSWI). Recently, PBDD/Fs from MSWI attracted rising concern because their important precursors, i.e., brominated flame retardants (BFRs), were frequently found in various wastes for landfill or MSWI feedstock. So far, however, little is known about PBDD/Fs and their associated risks in the vicinal environments of MSWI. Here we analyzed PBDD/Fs and PCDD/Fs in 29 soil samples collected around a multiyear large-scale MSWI, and compared their spatial distributions, sources and risks. PBDD/Fs demonstrated comparable concentrations and toxic equivalent quantities (TEQs) to PCDD/Fs in these samples. Spatially, both the concentrations of PBDD/Fs and PCDD/Fs decreased outwards from the MSWI, and exhibited significant linear correlations with the distances from the MSWI in the southeast downwind soil, suggesting the influence of the MSWI on its vicinal soil environment. However, the existence of other dioxin sources concealed its influence beyond 6 km. PBDD/Fs in the soils were characterized by highly-brominated PBDFs, especially Octa-BDF, and their sources were diagnosed as the MSWI and diesel exhaust; PCDD/Fs, however, were dominated by highly-chlorinated PCDDs, particularly Octa-CDD, and were contributed individually or jointly by the MSWI, automobile exhaust and pentachlorophenol (PCP)/Na-PCP. The non-carcinogenic risks of dioxins in all the soil samples were acceptable, but their carcinogenic risks in 17% of the samples were unacceptable. These samples were all located close to the MSWI and highways, therefore, the land use of these two high-risk zones should be cautiously planed.

A review of measurement techniques for aerosol effective density.

Density (ρ) is one of the most important physical properties of aerosol particles. Owing to the complex nature of aerosols and the challenges of measuring them, effective density (ρe) is generally used as an alternative measure. Various methods have been developed to quantify the ρe of aerosols, which provide powerful technical support and understanding of their physical properties. Here, we present a comprehensive review of the characterisation techniques of ρe currently used in the literature. Overall, six categories of measurement are identified, and the typical configuration, measurement principles, errors and field applications of each are demonstrated. Their respective advantages and disadvantages are also discussed to improve their application. Finally, we outline future directions for further technical improvement in, and instrumental development for, ρe measurement.

Occurrence of Dechlorane series flame retardants in sediments from the Pearl River Delta, South China.

Dechlorane series flame retardants (DECs), e.g. Dechlorane plus (DP), have reportedly showed an increase in consumption since the phase-out of traditional brominated flame retardants (BFRs). Here we investigated DP and 7 structural analogues, as well as its 2 dechlorinated products in 76 surficial sediments from the Pearl River Delta (PRD), one of the three important manufacturing bases of China. The concentration of Σ8DECs varied from 28.1 to 38,000 pg g-1 dw in the PRD sediments, dominated by DP and Mirex. Spatially, sedimental DP concentrations were significantly and positively correlated with the municipal gross domestic product (GDP), population and sewage discharge of the PRD cities, but were insignificantly related to their industrial outputs. This indicates that DP in the PRD sediments mainly originated from urban activities instead of industrial ones. Although Mirex has been restricted for several decades, it demonstrated ubiquity in the PRD and considerably high levels in several termite control hot-spots (up to 34,200 pg g-1), implying its massive historical use in this subtropical region. Other DECs, however, exhibited quite low abundances, implying their limited applications in this region. In comparison to the historical data, sedimental DP concentrations presented an increasing trend in most rivers in the PRD except the West River. The fractions of anti-DP (fanti) showed insignificant deviations from its technical value, suggesting that no obvious anti-DP transformation occurred in most PRD sediments. However, anti-Cl11-DP, an important dechlorination product of anti-DP, was ubiquitously found in the PRD sediments, and its concentrations were significantly and positively associated with those of anti-DP. Therefore, anti-Cl11-DP in the PRD sediments was deemed as the impurity co-emitted with anti-DP rather than its dechlorination byproduct. Considering its ubiquity, increasing trend and persistence, DP in the PRD environments merits continuous concerns.

Filter-based absorption enhancement measurement for internally mixed black carbon particles over southern China.

The effect of the mixing state of black carbon (BC) on light absorption is of enduring interest due to its close connection to regional/global climate. Herein, we present concurrent measurements of both BC absorption enhancement (Eabs) and the chemical mixing state in southern China. Eabs was obtained by simultaneous measuring the light absorption coefficient using an aethalometer before and after being heated. The observed Eabs was categorized into non- (Eabs ≤ 1.0), slight (1.0 < Eabs ≤ 1.2), and higher (Eabs > 1.2) enhancement groups, and it was compared to the mixing state of elemental carbon (EC) particles detected by a single particle aerosol mass spectrometer (SPAMS). The individual EC-containing particles were classified into four types, including EC with sodium and potassium ion peaks (NaK-EC), long EC cluster ions (Cn+/-, n ≥ 6) with sulfate (EC-Sul1), short EC cluster ions (Cn+/-, n < 6) with sulfate (EC-Sul2), and EC with OC and sulfate (ECOC-Sul). NaK-EC and EC-Sul2 are the dominant EC types. Slight enhancement group is mainly explained by the photochemical production of ammonium sulfate and organics on EC-Sul2 during afternoon hours. In contrast, the higher Eabs is primarily attributed to the enhanced mixing of ammonium chloride with NaK-EC during morning hours, without photochemistry. The characterization of source emissions indicates that NaK-EC is likely from coal combustion and is associated with a relatively higher amount of ammonium chloride. To our knowledge, this is the first report to state that EC particles associated with ammonium chloride have a relatively higher Eabs.

Does atmospheric processing produce toxic Pb-containing compounds? A case study in suburban Beijing by single particle mass spectrometry.

A single particle aerosol mass spectrometry (SPAMS) was deployed to investigate the mixing state and chemical processing of Pb-rich particles in suburban Beijing. Based on a large dataset of mass spectra, Pb-rich particles were classified into Pb-O-Cl-N-S (55%), Pb-N (17%), Pb-N-S (15%), and Pb-EC (7%). Residual coal combustion, industrial activities, and meteorological conditions were identified as main factors regulating the variations of Pb-rich particles in the atmosphere. The highest abundance of the Pb-rich particles was observed during heating period (HP) primarily due to the increase in coal usage. Pb in Pb-O-Cl-N-S type was identified in forms of PbO, PbCl2, and Pb(NO3)2. Dominantly presented in the form of Pb(NO3)2, Pb-N type represented the completely transformed Pb-rich particles from PbO/PbCl2 by atmospheric processes. It is found that PbCl2 and PbO could be transformed to Pb(NO3)2, highly dependent on the amount of NO2 and RH. Significant enhancement of nitrate in Pb-O-Cl-N-S particles was observed when the RH was greater than 60%, emphasizing the importance of heterogeneous hydrolysis of N2O5 on the formation of Pb(NO3)2. Compared with non-carcinogenic PbCl2/PbO and insoluble PbO, soluble and carcinogenic Pb(NO3)2 produced by atmospheric processes may significantly enhance negative effects of Pb-rich particles on human health and the ecosystem.

Inflammation Response of Water-Soluble Fractions in Atmospheric Fine Particulates: A Seasonal Observation in 10 Large Chinese Cities.

Spatiotemporal trends in pro-inflammatory (interleukin (IL)-6 and IL-8) release after exposure to the water-soluble fractions of PM2.5 sampled in 10 large Chinese cities over 1 year were investigated. Chemical components (water-soluble ions, metal(loid) elements, water-soluble organic carbon (WSOC), humic-like substances (HULIS), and endotoxins) in PM2.5 samples were measured, and the molecular structure of WSOC was also analyzed by nuclear magnetic resonance. Changes in DNA methylation and gene expression of candidate genes were also evaluated to explore the potential mechanisms. PM2.5 from southern cities induced lower pro-inflammatory responses compared to those from northern cities. Seasonal differences in toxicity were noted among the cities. IL-6 was significantly correlated with HULIS (as the main fraction of WSOC with oxygenated carbohydrate structures characteristic), Pb, and endotoxin. Furthermore, DNA methylation and gene expression changes in RASSF2 and CYP1B1 were related to pro-inflammatory secretion. Certain components of PM2.5, rather than PM2.5 mass itself, determine the pro-inflammatory release. In particular, HULIS, which originated from primary biomass burning and residual coal combustion, and secondary organic aerosols, appear to be the key component in PM2.5 to induce human health risk.

Brominated and organophosphate flame retardants along a sediment transect encompassing the Guiyu, China e-waste recycling zone.

e-Waste recycling using crude techniques releases a complex, yet incompletely characterized mixture of hazardous materials, including flame retardants (FRs), to the environment. Their migration downstream and the associated risks also remain undocumented. We examined 26 FRs (18 brominated (BFRs: 12 polybrominated diphenyl ether (PBDE) congeners, plus 6 alternatives) and 8 organophosphate esters (OPEs)) in surficial sediments of the Lian River. Sampling encompassed the river's origin, through the Guiyu e-waste recycling zone, to its mouth, as well as associated tributaries. OPE exceeded BFR concentrations in most sediments, despite their far greater water solubilities. Among OPEs, tris(1-chloro-2-propyl) phosphate dominated upstream, but shifted to triphenyl phosphate in Guiyu and downstream sediments. For PBDEs, Deca-BDE dominated upstream, but Penta-BDE prevailed in Guiyu and at many downstream sites. Among emerging alternative BFRs, decabromodiphenyl ethane dominated upstream, transitioning to 1,2-bis(2,4,6,-tribromophenoxy)ethane in Guiyu sediments. Penta-BDE (BDE-47 + -99, 668-204,000 ng g-1, ∑PBDEs 2280-287,000 ng g-1), tetrabromobisphenol A (2,720-41,200 ng g-1), 1,2-bis(2,4,6,-tribromophenoxy)ethane (222-9870 ng g-1) and triphenyl phosphate (4260-1,710,000 ng g-1, OPEs 6010-2,120,000 ng g-1) concentrations in Guiyu sediments were among the highest reported in the world to date. The continuing dominance of these e-waste indicative FRs in sediments downstream of Guiyu suggested that FR migration from Guiyu occurred. Hazard quotients >1.0 indicated that the extreme sediment concentrations of individual FRs posed ecological risks in most Guiyu reach and downstream areas. Simultaneous exposure to multiple FRs likely increased risks. However, risks may be mediated if FRs were associated with strong sorbents, e.g. carbon black from burned debris, hydrophobic polymer fragments, or resided as additives within polymer fragments.

Oxalate Formation Enhanced by Fe-Containing Particles and Environmental Implications.

We used a single particle mass spectrometry to online detect chemical compositions of individual particles over four seasons in Guangzhou. Number fractions (Nfs) of all the measured particles that contained oxalate were 1.9%, 5.2%, 25.1%, and 15.5%, whereas the Nfs of Fe-containing particles that were internally mixed with oxalate were 8.7%, 23.1%, 45.2%, and 31.2% from spring to winter, respectively. The results provided the first direct field measurements for the enhanced formation of oxalate associated with Fe-containing particles. Other oxidized organic compounds including formate, acetate, methylglyoxal, glyoxylate, purivate, malonate, and succinate were also detected in the Fe-containing particles. It is likely that reactive oxidant species (ROS) via Fenton reactions enhanced the formation of these organic compounds and their oxidation product oxalate. Gas-particle partitioning of oxalic acid followed by coordination with Fe might also partly contribute to the enhanced oxalate. Aerosol water content likely played an important role in the enhanced oxalate formation when the relative humidity is >60%. Interactions with Fe drove the diurnal variation of oxalate in the Fe-containing particles. The study could provide a reference for model simulation to improve understanding on the formation and fate of oxalate, and the evolution and climate impacts of particulate Fe.

Assessment of exposure to polybrominated diphenyl ethers associated with consumption of market hens in Guangzhou.

To evaluate contamination by polybrominated diphenyl ethers (PBDEs) in market hens and human PBDE exposure via hen consumption in Guangzhou, hens were collected and their muscle, liver, fat, blood, yolk, and ingluvies tissues were analyzed for 13 PBDE congeners. The median highest concentration of ∑PBDEs was found in the ingluvies (5.30 ng/g lw), followed by the muscle (2.53 ng/g lw), with the lowest located in the yolk (0.09 ng/g lw). The concentrations of PBDEs in the muscle tissue of market hens in Guangzhou were at medium levels compared to others reported around the world. BDE-47, -153, -99, and -183 were the predominant congeners. The daily intake concentrations of PBDEs from hen muscle were estimated to range from 0.08 to 0.31 ng/kg/day in this study, with a Hazard Quotient (HQ) below 1.0. These results suggest that the health risk of PBDEs for the general population, through the consumption of market hens in Guangzhou, was generally low. However, the intake of PBDEs via food consumption may be one major exposure pathway for the general population of Guangzhou.

Effects of lead, cadmium, arsenic, and mercury co-exposure on children's intelligence quotient in an industrialized area of southern China.

Exposure to metal(loid)s can lead to adverse effects on nervous system in children. However, little is known about the possible interaction effects of simultaneous exposure to multiple metal(loid)s on children's intelligence. In addition, relationship between blood lead concentrations (<100 µg/L) and the intelligence of children over 5 years needs further epidemiological evidence. We recruited 530 children aged 9-11 years, including 266 living in a town near an industrialized area and 264 from another town in the same city in South China as a reference. The levels of lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in blood (BPb, BCd, BAs, BHg) and urine (UPb, UCd, UAs, UHg) were assessed, as well as children's intelligence quotient (IQ). A significant decrease in IQ scores was identified in children from the industrialized town (p < .05), who had statistically higher geometric mean concentrations of BPb, BCd, UPb, UCd and UHg (65.89, 1.93, 4.04, 1.43 and 0.37 µg/L, respectively) compared with children from the reference town (37.21, 1.07, 2.14, 1.02 and 0.30 µg/L, respectively, p < .05). After adjusting confounders, only BPb had a significant negative association with IQ (B = -0.10, 95% confidence interval: -0.15 to -0.05, p < .001), which indicated that IQ decreased 0.10 points when BPb increased 1 µg/L. Significant negative interactions between BAs and BHg, positive interaction between UPb and UCd on IQ were observed (p < .10), and BPb <100 µg/L still negatively affected IQ (p < .05). Our findings suggest that although only BPb causes a decline in children's IQ when simultaneously exposed to these four metal(loid)s at relatively low levels, interactions between metal(loid)s on children's IQ should be paid special attention, and the reference standard in China of 100 µg/L BPb for children above 5 years old should be revised.

Polychlorinated biphenyls and their hydroxylated metabolites in the serum of e-waste dismantling workers from eastern China.

A number of studies have reported on the exposure of e-waste dismantling workers to significantly high concentrations of halogenated organic pollutants such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers. Such exposure can have adverse health effects. However, little information on the metabolites of these contaminants exists. In this study, we investigated PCBs levels and their hydroxylated metabolites (OH-PCB) in the serum of e-waste workers in Taizhou in eastern China. Our results indicate elevated PCB and OH-PCB levels in the serum of the workers, with medians of 443.7 and 133.9 ng/g lw, respectively. Tri- to hexachlorinated PCB congeners were the dominant homologue groups in all of the samples. 4-OH-CB107 was the predominant homologue among the hydroxylated metabolites, accounting for 88.9% of the total OH-PCB concentrations. While dietary sources (e.g., fish) appear to be an important route for PCB accumulation in non-occupational exposure groups, exposure via ingestion of house dust and inhalation of pollutants derived from the recycling of PCB-containing e-wastes may primarily contribute to the high body burden observed in the occupational groups. Since we found concentrations of metabolites higher than those of their parent compounds, further studies need to pay more attention to their bioaccumulation and toxicity.

The Potential of Alkyl Amides as Novel Biomarkers and Their Application to Paleocultural Deposits in China.

A series of alkyl amides was detected and identified in the sedimentary record from an archaeological site at Yuchisi, Mengcheng, Anhui, China. The alkyl amides profiles change abruptly at the depth corresponding to the transition between two prehistoric cultures, which also corresponds to an abrupt change in the fatty acid ratio C18:2/C18:0. The different patterns of variation of the longer and shorter chain alkyl amides at the depth of the cultural transition may reflect differences in their response to external environmental changes, as well as different sources. This is the first study of the stratigraphic variation of alkyl amides in sediments, and their first application to assess paleoenvironmental changes. We suggest that alkyl amides may have potential as new biomarkers in archeological and paleoenvironmental studies.

Two new oxygen-containing biomarkers isolated from the Chinese Maoming oil shale by silica gel column chromatography and preparative gas chromatography.

Two biomarkers, 5,9-dimethyl-6-isopropyl-2-decanone (1) and 4,9,11-trimethyl-6-isopropyl-2-dodecanone (2), were isolated from Chinese Maoming oil shale by silica gel column chromatography and preparative gas chromatography. Their structures were elucidated by using spectroscopic techniques.

[Light Absorption Properties of Water-Soluble Organic Carbon (WSOC ) Associated with Particles in Autumn and Winter in the Urban Area of Guangzhou].

Light absorption properties of water-soluble organic carbon (WSOC) were investigated in the urban area of Guangzhou. The fine particulate matter (PM2.5) and size-segregated samples were collected in September and December of 2014 and January of 2015. The variation of absorption with wavelength of WSOC was characterized by the absorption Angström exponent (AAEabs). The AAE values of WSOC in PM2.5 were 3.72 ± 0.41 in autumn and 3.91 ± 0.70 in winter, which were lower than those in Beijing and north America. The mass absorption efficiency (MAE) of WSOC at 365 nm wavelength was 0.52 m² · g⁻¹ in autumn and 0.92 m² · g⁻¹ in winter, exhibiting distinct variations between autumn and winter. In winter, the MAEwsoc values exhibited a decreasing trend with increasing particle size, and all size-segregated MAE(WSOC) values in autumn were lower than those in winter, particularly for the particles < 0.95 µm, suggesting more contribution of the secondary formation to WSOC. Comparing the MAE values of elemental carbon (EC) and WSOC, it could be found that the contribution of WSOC to the light extinction of particles couldn't be ignored when the particles were mainly emitted from primary sources.

LINE-1 gene hypomethylation and p16 gene hypermethylation in HepG2 cells induced by low-dose and long-term triclosan exposure: The role of hydroxyl group.

Triclosan (TCS), a frequently used antimicrobial agent in pharmaceuticals and personal care products, exerts liver tumor promoter activities in mice. Previous work showed high-dose TCS (1.25-10µM) induced global DNA hypomethylation in HepG2 cells. However, whether or how tumor suppressor gene methylation changed in HepG2 cells after low-dose and long-term TCS exposure is still unknown. We investigate here the effects and mechanisms of DNA methylation of global DNA(GDM), repetitive genes, and liver tumor suppressor gene (p16) after exposing HepG2 cells to low-dose TCS (0.625-5nM)for two weeks using HPLC-MS/MS, Methylight, Q-MSP, Pyrosequencing, and Massarray methods. We found that low-dose TCS exposure decreased repetitive elements LINE-1 methylation levels, but not global DNA methylation, through down-regulating DNMT1 (DNA methyltransferase 1) and MeCP2 (methylated DNA binding domain) expression, and up-regulating 8-hydroxy-2-deoxyguanosine (8-OHdG) levels. Interestingly, low-dose TCS elevated p16 gene methylation and inhibited p16 expression, which were not observed in high-dose (10µM) group. Meanwhile, methyl-triclosan could not induce these two types of DNA methylation changes, suggesting the involvement of hydroxyl in TCS-mediated DNA methylation changes. Collectively, our results suggested low concentrations of TCS adversely affected HepG2 cells through DNA methylation dysregulation, and hydroxyl group in TCS played an important role in the effects. This study provided a better understanding on hepatotoxicity of TCS at environmentally relevant concentrations through epigenetic pathway.