Chlorinated paraffins in sediments from the Pearl River Delta, South China: spatial and temporal distributions and implication for processes

Short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) were measured in sediments from ponds, rivers and tributaries, and an estuary, as well as a sediment core in the Pearl River Delta (PRD), South China, to comprehensively investigate the spatial and temporal distributions of CPs. The concentrations of SCCPs and MCCPs in sediment were varied from 320 to 6600 ng/g and from 880 to 38,000 ng/g, respectively. Elevated CP concentrations were found in pond sediments (means of 2800 and 21,000 ng/g for SCCPs and MCCPs) in the e-waste recycling area and in river sediments (means of 1200 and 3900 ng/g for SCCPs and MCCPs) in the highly industrialized areas. The significant positive correlations between SCCP concentration and MCCPs/SCCPs in the highly industrialized areas reflected the emission of local industry activities, while the significant negative correlations in the low industrial activity areas could be linked to long-range transportation of CPs. An increased abundance of short chain and low chlorinated congeners was observed in the low industrial activity areas compared to the industrialized areas. The preferred transportation of short chain and low chlorinated congener CPs and the dechlorination of higher chlorinated congeners CPs were the most likely reasons. The vertical profile of CPs in the sediment core indicated a rapid increase in the usage of CPs and a shift to more MCCPs in recent years. The decreased chlorine content of CPs with increasing sediment depth indicated the possibility of dechlorination of higher chlorinated congeners (Cl(9) and Cl(10)) after deposition in sediments with greater dechlorination potential for short chain CPs than long chain CPs.     

Environmental occurrence and distribution of short chain chlorinated paraffins in sediments and soils from the Liaohe River Basin, P. R. China

Chlorinated paraffins (CPs) are industrially produced in large quantities in the Liaohe River Basin. Their discharge inevitably causes environmental contamination. However, very limited information is available on their environmental levels and distributions in this typical industrial region. In this study, short chain CPs (SCCPs) were analyzed in sediments, paddy soils, and upland soils from the Liaohe River Basin, with concentrations ranging from 39.8 to 480.3 ng/g dry weight. A decreasing trend in SCCP concentrations was found with increasing distance from the cities, suggesting that local industrial activity was the major source of SCCP contamination. A preliminary sediment inventory of SCCPs indicated approximately 30.82 tonnes of SCCPs residual in the sediments from the Liaohe River. The average discharge of SCCPs was estimated to be about 74.4 mg/tonne industrial wastewater. The congener group profiles showed that the relative abundances of shorter chain and lower chlorinated CP congeners (C(10)-CPs with 5 or 6 chlorine atoms) in soils in rural areas were higher than in sites near cities, which demonstrated that long-range atmospheric transportation could be the major transport pathway. Environmental degradation of SCCPs might occur, where higher chlorinated congeners could dechlorinate to form the lower chlorinated congeners.     

Historical profiles of chlorinated paraffins and polychlorinated biphenyls in a dated sediment core from Lake Thun (Switzerland)

A dated sediment core from Lake Thun covering the last 120 years was analyzed to get an overview of the historical trend of the chlorinated paraffin (CP) and polychlorinated biphenyl (PCB) deposition, because CPs and PCBs have/had similar applications as plasticizers and flame retardants. Total CP concentrations (sum of short chain (SCCP), medium chain (MCCP), and long chain CPs (LCCP)) showed a steep increase in the 1980s and a more-or-less stable level of 50 ng g(-1) dry weight (dw) since then. The concentration-time profile is in good agreement with the available information on global production data. The quantification of higher chlorinated SCCPs using electron capture negative ionization low resolution mass spectrometry (ECNI-LRMS) revealed an increase in recent years. In addition, the degree of chlorination of SCCPs has strongly increased during the past 40 years, which may indicate its use as an additive for plastics, paints, and coatings. Furthermore, PCBs were analyzed in dated sediment slices. The PCB concentrations (sum of the six indicator congeners) peaked around 1969 (18 ng g(-1) dw) and decreased to 1.3 ng g(-1) dw in the surface layer corresponding to 2004. The peak level of CPs exceeded those of PCBs by about a factor of 3.     

食用菌中氯化石蜡的污染水平及摄入风险评估

目的 了解中国市场上食用菌中氯化石蜡(Chlorinated paraffins, CPs)的污染状况, 为CPs的综合摄入风险评估提供科学数据。方法 采集中国市场上24种不同食用菌品种(共计79个样品)。样品经加速溶剂萃取(accelerated solvent extraction, ASE)、净化, 采用电子捕获负离子模式下气相色谱-质谱法(gas chromatography- mass spectrometry, GC-MS)检测, 分析CPs的浓度与同族体分布。结果 在不同品种的食用菌样品中, 短链氯化石蜡(short-chain chlorinated paraffins, SCCPs)干重浓度范围在92.75~3688.35 ng/g之间, 平均浓度为797.49 ng/g; 中链氯化石蜡(medium-chain chlorinated paraffins, MCCPs)干重浓度范围在未检测到(Not detected, ND)~588.68 ng/g之间, 平均浓度为235.78 ng/g。SCCPs的同族体组成以C10Cl8为主, MCCPs的同族体以C14Cl8为主。线性判别分析(linear discriminant analysis, LDA)表明不同食用菌样品中的CPs的污染模式无明显差异。SCCPs和MCCPs的估计每日摄入量(estimated daily intake, EDI)平均值分别为334.67和99.01 ng·kg-1·d-1, 由此计算的暴露边界值(margin of exposure, MOE)大于1000。结论 食用菌样品中SCCPs和MCCPs有着相似来源, 其摄入量低于SCCPs和MCCPs间接暴露风险阈值（10和4 mg·kg-1·d-1）。表明食用菌中CPs对居民没有潜在的健康风险。     

Bioaccumulation and trophic magnification of short- and medium-chain chlorinated paraffins in food webs from Lake Ontario and Lake Michigan

Chlorinated paraffins (CPs) are complex mixtures of chlorinated alkanes used in a myriad of industrial applications as flame retardant plasticizers and additives. In this study, the distribution and bioaccumulation/biomagnification of short-chain CPs (C10-C13, SCCPs) and medium-chain CPs (C14-C17, MCCPs) were investigated in samples collected between 1999 and 2004 from Lake Ontario and northern Lake Michigan. Total (sigma) SCCPs and sigmaMCCPs concentrations in water from Lake Ontario were 1190 pg/L and 0.9 pg/L (data from 2004 only), respectively. CPs were also detected in invertebrates and fish from both lakes. SCCP predominated in organisms from Lake Michigan with the highest mean concentrations found in lake trout [Salvelinus namaycush, 123 +/- 35 ng/g wet weight (ww)]. In Lake Ontario, MCCPs predominated in most species with the highest levels detected in slimy sculpin (Cottus cognatus, 108 ng/g ww) and rainbow smelt (Osmerus mordax, 109 ng/g ww). Bioaccumulation and biomagnification of CPs was evaluated on an isomer basis (i.e., C10H17Cl5, C10H16Cl6, etc). Log bioaccumulation factors for lake trout (lipid based) ranged from 4.1 to 7.0 for SCCPs and 6.3 to 6.8 for MCCPs. SCCPs and MCCPs were found to biomagnify between prey and predators from both lakes with highest values observed for Diporeia-sculpin (Lake Ontario, C15Cl9 = 43; Lake Michigan, C10Cl5 = 26). Trophic magnification factors for the invertebrates-forage fish-lake trout food webs ranged from 0.41 to 2.4 for SCCPs and from 0.06 to 0.36 for MCCPs. Given the prominence of CPs, particularly in lake waters and in lower food web organisms, further investigation is needed to evaluate the magnitude of their distribution and accumulation/magnification in the Great Lakes environment.     

Distribution and trophic transfer of short-chain chlorinated paraffins in an aquatic ecosystem receiving effluents from a sewage treatment plant

Short-chain chlorinated paraffins (SCCPs) are an extremely complex group of industrial chemicals and found to be potential persistent organic pollutants (POPs), and thus have attracted extensive concern worldwide. In this study, influent, effluent, and sludge were collected from a large sewage treatment plant (STP) in Beijing, China. Water, sediment, and aquatic species were also collected from a recipient lake that receives effluents discharged from the STP. These samples were then analyzed to investigate the effect of STP effluent on distribution and trophic transfer of SCCPs in the local aquatic ecosystem. Concentrations of total SCCPs (ΣSCCPs) in lake water and surface sediments were found in the range 162-176 ng/L and 1.1-8.7 μg/g (dry weight, dw), respectively. Vertical concentration profiles of sediment cores showed ΣSCCPs decreased exponentially with increasing depth. Specific congener composition analysis in sediment layers indicated possible in situ biodegradation might be occurring. High bioaccumulation of SCCPs was observed in the sampled aquatic species. The bioaccumulation factor (BAF) generally increased with the number of chlorines in the SCCP congeners. A significantly positive correlation between lipid-normalized ΣSCCPs concentration and trophic levels (R(2) = 0.65, p < 0.05) indicate that SCCPs can biomagnify through the food chain in the effluent-receiving aquatic ecosystem.     

Short chain chlorinated paraffins in mollusks from coastal waters in the Chinese Bohai Sea

As an extremely complex group of persistent organic pollutants (POPs) candidates in the Stockholm Convention, short chain chlorinated paraffins (SCCPs) have been of extensive concern in recent years. In this study, nine bivalve and two gastropod species were collected in 2009 to evaluate the spatial distributions and potential factors influencing the bioaccumulation of SCCPs in mollusks in the Chinese Bohai Sea. The concentrations of ∑ SCCPs in the mollusks were in the range 64.9-5510 ng/g (dry weight) with an average chlorine content of 61.1%. C(10) and C(11) were the predominant homologue groups of SCCPs, which accounted for about 29.7% and 34.9% of ∑ SCCPs, respectively. Six and seven chlorinated substituents were the main congener groups. Mya arenaria (Mya), Mactra veneriformis (Mac), and Crassostrea talienwhanensis (Oyster, Ost) had higher average concentrations of SCCPs than other species, implying that these bivalves could be used as sentinels to indicate SCCPs contamination in this coastal region. A significant positive linear relationship was found between SCCP concentrations and lipid content of the mollusks, whereas the lipid-normalized SCCP concentrations were negatively linear-related to the trophic levels (TL), which implied that SCCPs did not show biomagnification in mollusks in this region.     

膳食中短链氯化石蜡的污染状况及风险暴露评估

短链氯化石蜡（short chain chlorinated paraffins,SCCPs）是碳原子数在10～13之间的氯化石蜡（chlorinated paraffins,CPs）,它是一类结构复杂的混合物。目前,膳食中SCCPs污染状况的检测数据较少。为了解我国北部膳食中SCCPs的污染现状,于2016年在9 个城市分别采集了9 种膳食样品,共计81 份,采用在线凝胶渗透色谱-气相色谱-负化学离子源-质谱测定膳食样品中SCCPs含量并分析其同系物的分布模式。结果表明,膳食样品中SCCPs含量范围为2.30～496.49 ng/g（湿质量）,并且同系物分布以低氯取代Cl6～Cl7的C10-/C12-SCCPs为主要组成部分。我国华北地区人群的膳食暴露风险在1.1～3.8之间。膳食暴露风险小于100,即说明膳食暴露风险尚可接受,但这并不意味着对人类健康没有存在风险。测定膳食中的SCCPs含量并分析其分布模式,为了解我国膳食中SCCPs的污染状况及其对人体健康的影响提供了数据参考。     

Polychlorinated naphthalene levels,distribution, and biomagnification in a benthic food chain in the Baltic Sea

The scientific literature contains little information regarding bioaccumulation and biomagnification of polychlorinated naphthalenes (PCNs) in food webs. Here we present new information on the food chain transfer of PCNs within a food chain in a subarctic environment PCNs (tetra- to hepta-chloro congeners) were measured in surface sediments and in a marine benthic food chain, comprising amphipods, isopods, and fourhorned sculpins. Samples were collected from five locations in the Gulf of Bothnia, northern Baltic Sea. PCN concentrations in the sediments were similar to background levels determined previously in sediments from the northern hemisphere. Measurement of the carbon content of the sediments allowed the calculation of biota to sediment accumulation factors (BSAFs). Tetra- and penta-CNs exhibited BSAF values greater than one, while BSAFs for the more chlorinated PCNs were less than one. This suggests more efficient assimilation, by amphipods, of the less chlorinated PCNs. A decrease in sigmaPCN concentrations from the lowest to the highest trophic level was demonstrated (amphipods: 10-69 ng/g lw, isopods: 3.9-16 ng/g lw; fourhorned sculpins: 0.54-1.5 ng/g lw). Biomagnification factors (BMFs) were calculated based on the concentrations of the congeners. These indicated that a few congeners biomagnified significantly: the highest BMFs (0.09-1.4) were found for 2,3,6,7-substituted congeners and those lacking adjacent hydrogen-substituted carbon atoms.     

短链氯化石蜡毒性效应及检测技术研究进展

链氯化石蜡(short chain chlorinated paraffins,SCPPs)是一类结构复杂的混合物,在工业生产中用途广泛,主要用作金属加工润滑剂、PVC增塑剂、高分子材料阻燃剂、油漆、密封剂、粘合剂等。本文对短链氯化石蜡的毒性效应和环境污染现状进行了综述。研究了SCCPs对于哺乳动物、鱼类和两栖类、鸟类的毒理学效应,指出了毒理学领域存在的问题及研究需求。文章还对SCCPs作为持久性有机污染物的特性(持久性、生物蓄积性及长距离迁移性)以及SCCPs在环境介质(水、土壤和底泥、大气、食品)中的污染状况和检测技术进行了阐述。并总结了SCCPs研究中存在的问题,指出SCCPs的检测方法仍然是环境中SCCPs研究存在的突出问题。     

The absorption and translocation of polychlorinated biphenyl congeners by Cucurbita pepo ssp pepo

The mobility of polychlorinated biphenyl (PCB) congeners within Cucurbita pepo ssp pepo cv. Howden (pumpkin), a PCB phytoextracting plant, was investigated through a comparison of field-weathered soil, root, shoot, and xylem sap congener profiles. This is the first study to show the presence of PCBs in xylem sap (range: 0.03-0.18 μg·mL(-1)), confirming that PCB translocation throughout the plant occurs via this medium. A comparison of soil (5.2 ± 2.5 μg·g(-1)), root (27.1 ± 2.1 μg·g(-1)), shoot (range: 1.9 ± 0.5 μg·g(-1) - 8.2 ± 1.4 μg·g(-1)), and xylem sap (0.09 ± 0.04 μg·g(-1)) samples showed significant differences in congener profiles, with lower chlorinated congeners (predominately trichlorinated ones) found within xylem sap in higher amounts than higher chlorinated congeners. The total PCB concentrations of xylem sap samples collected at various lengths along the primary plant shoot were not significantly different from each other, while those of primary shoot tissue samples significantly decreased (two-sample t test, p = 0.01) as the distance from the plant base increased. PCA analysis of individual congeners in the roots, shoots and xylem sap indicated that movement of the PCB congeners in the plant was affected by the number of chlorines in the molecule, and hence possibly log K(ow) and molecular weight, but not by planarity.     

Facilitated transport of dioxins in soil following unintentional release of pesticide-surfactant formulations

Colloids such as surfactant micelles can act as transport facilitators for highly lipophilic, generally immobile contaminants in soil. Following a fire at a pesticide facility, this study investigated vertical and lateral migration of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in heterogeneous soil beneath bunded ponds, where contaminated wastewater containing high surfactant loads was stored until remediation. Initially, surface and subsurface soil was obtained during excavation, and subsequently intact cores to 5.7 m were collected. ΣPCDD/F concentrations were elevated in the wastewater (15-81 ng/L) and correspondingly in pond surface soils (6.1-61 ng/g). Maximum ΣPCDD/F concentrations were, however, observed at 2-2.5 m depth (68-130 ng/g), far below their expected mobility range based on physicochemical properties. Congener specific analysis further indicated that PCDD/F mobility was reversed, with the least water-soluble congener migrating to the greatest extent. The presence of higher chlorinated PCDD/Fs throughout a core collected in the direction of groundwater flow indicated subsequent lateral transport. These results provide field evidence for rapid vertical migration (2.4 m in <4 months) of highly lipophilic PCDD/Fs and suggest surfactant facilitated transport as the dominant transport mechanism. Quantification and evaluation of such fundamental changes in contaminant transport and fate in the presence of surfactants is required to identify areas at risk of groundwater contamination.     

Health risks of heavy metals in sewage‐irrigated soils and edible seeds in Langfang of Hebei province,China

BACKGROUND: Human exposure to heavy metals is attributed to consumption of food crops grown in polluted soil environment. The objective of our study was to assess the health risks of heavy metals in edible seeds of crops grown in sewage‐irrigated soils located in the Langfang of Hebei province, China. Here, heavy metal contents in soils and plants were determined using an internal standard and high‐resolution inductively coupled plasma mass spectrometry. RESULTS: There was a relative buildup of heavy metals in sewage‐irrigated soils in the study area; in particular, all Cr and partial Zn and Cu showed higher concentrations than the limits proposed by the World Health Organization, European Union (EU) and UK. Heavy metal concentrations in edible seeds of plants grown in sewage‐irrigated soils partly exceeded the permissible limits set by the EU, UK and the State Environmental Protection Administration in China. With the exception of Cu, health risk index values of each heavy metal investigated by intake of the edible seeds were less than 1. Here, a health risk index of < 1 is considered safe for human consumption. CONCLUSION: The study indicated that there was a relative absence of health risks associated with the ingestion of sewage‐irrigated edible seeds. Copyright © 2009 Society of Chemical Industry     

Effect of sewage-sludge application on concentrations of higher-brominated diphenyl ethers in soils and earthworms

Polybrominated diphenyl ethers (PBDEs), including octa-decaBDEs, were found in soil and earthworm samples collected in 2000 from three research stations (reference plots and sewage-sludge-amended plots) and two farms (reference and amended/flooded soils) in Sweden. Sewage-sludge amendment at the research stations increased concentrations of all BDE congeners 2- to 13-fold, with the highest increases for BDE-209. Concentrations 100-to 1000-fold higher were seen in contaminated soils at both farms. BDE-209 was the predominant congener in all soils. sigmaPBDE concentrations in worms ranged from 3.1 to 38 000 ng/g lipid weight and were correlated to soil concentrations, including the octa-decaBDEs. Biota-soil accumulation factors declined in the following order: TeBDE > PeBDE > HxBDE > OcBDE > NoBDE > DeBDE, and ranged from 0.3 to 2 for the octa-decaBDEs. Thus, higher-brominated PBDEs, including BDE-209, are bioavailable from soils and accumulate in earthworms, presenting an exposure pathway into the terrestrial food web. High levels found at one farm 20 years after the last use of PBDEs indicate high persistence of PBDEs in soils, including BDE-209. No evidence of photolytic debromination of BDE-209 in soils was seen.     

Chloride and organic chlorine in forest soils: storage, residence times, and influence of ecological conditions

Recent studies have shown that extensive chlorination of natural organic matter significantly affects chlorine (Cl) residence time in soils. This natural biogeochemical process must be considered when developing the conceptual models used as the basis for safety assessments regarding the potential health impacts of 36-chlorine released from present and planned radioactive waste disposal facilities. In this study, we surveyed 51 French forested areas to determine the variability in chlorine speciation and storage in soils. Concentrations of total chlorine (Cl(tot)) and organic chlorine (Cl(org)) were determined in litterfall, forest floor and mineral soil samples. Cl(org) constituted 11-100% of Cl(tot), with the highest concentrations being found in the humus layer (34-689 mg Cl(org) kg(-1)). In terms of areal storage (53 - 400 kg Cl(org) ha(-1)) the mineral soil dominated due to its greater thickness (40 cm). Cl(org) concentrations and estimated retention of organochlorine in the humus layer were correlated with Cl input, total Cl concentration, organic carbon content, soil pH and the dominant tree species. Cl(org) concentration in mineral soil was not significantly influenced by the studied environmental factors, however increasing Cl:C ratios with depth could indicate selective preservation of chlorinated organic molecules. Litterfall contributions of Cl were significant but generally minor compared to other fluxes and stocks. Assuming steady-state conditions, known annual wet deposition and measured inventories in soil, the theoretical average residence time calculated for total chlorine (inorganic (Cl(in)) and organic) was 5-fold higher than that estimated for Cl(in) alone. Consideration of the Cl(org) pool is therefore clearly important in studies of overall Cl cycling in terrestrial ecosystems.     

Oral bioaccessibility of dioxins/furans at low concentrations (50-350 ppt toxicity equivalent) in soil

Animal studies have indicated that the oral bioavailability of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in environmentally contaminated soil could range from 0.5 to 60%. To estimate the oral bioavailability of TCDD, and the 16 other 2,3,7,8-substituted dioxin/furan congeners, this study used a physiologically based extraction test, designed around the anatomic and physiologic characteristics of the human digestive tract. This test measures the fraction of dioxins/furans in soil that would be solubilized in the gastrointestinal tract (i.e., that would be bioaccessible) and therefore available for absorption. Eight soils from Midland, MI, were evaluated in this study and exhibited TCDD concentrations of 1.7-139 pg/g (ppt) and total TEQ concentrations of 6-340 ppt. Bioaccessibility of dioxins/furans from these soils ranged from 19 to 34% averaged across the 17 2,3,7,8-substituted dioxin/furan congeners), with an average of 25%. The total organic carbon in these soils was low--ranging from 1 to 4%--particularly for the soil series from which they were collected. Bioaccessibility of individual congeners did not appear to be correlated with degree of chlorination. Even though these dioxin/furan concentrations are much less than studied previously, these results are consistent with those from animal studies at other sites, which have generally yielded values of 20-60% relative bioavailability for TCDD in soil.     

Polychlorinated dibenzo-p-dioxin and dibenzofuran concentration profiles in sediments and flood-plain soils of the Tittabawassee River,Michigan

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in sediments and flood-plain soils collected along the Tittabawassee River in Michigan ranged from 102 to 53,600 pg/g, dry wt. Mean PCDD/PCDF concentrations in downstream sediment and soil were from 10- to 20-fold greater than those found at locations upstream of Midland, Michigan. Concentrations of PCDD/PCDF in sediments and flood-plain soils from the Tittabawassee watershed were comparable to those found in industrialized areas such as the Housatonic and lower Passaic Rivers in the U.S. Concentrations of PCDDs/PCDFs in soil and sediment were not correlated with total organic carbon (TOC) in sediments or soils. OCDD and 2,3,7,8-TeCDF were the predominant congeners in sediment/soil collected from locations downstream of Midland, Michigan. Principal component analysis of the PCDD/PCDF congener profile suggested the presence of sources originating from a mixture of chlorophenol and other chlorinated compound production. Mass balance analysis of TCDD equivalents (TCDD-EQs) derived from H4IIE-luc bioassay of sediment extracts and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) estimated from instrumental analysis suggested that PCDDs/PCDFs were the major dioxin-like compounds present in sediments. A significant correlation existed between bioassay-derived TCDD-EQs and instrumentally measured TEQs (r2 = 0.94).     

Temperature dependence of the air concentrations of polychlorinated biphenyls and polybrominated diphenyl ethers in a forest and a clearing

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were quantified in 67 high volume air samples taken concurrently in a forest and a clearing in southern Ontario, Canada from October 2001 to November 2002. Air concentrations were comparable between the two sites. Gaseous PCBs ranged from 6.4 to 150 pg x m(-3), and gaseous PBDEs ranged from below method detection limit (BDL) to 55 pg x m(-3) (with two extreme events up to 290 pg x m(-3)). Particulate PBDEs ranged from BDL to 40 pg x m(-3). Gaseous concentrations of PCBs and PBDEs were highly temperature dependent, suggesting a relatively strong influence of re-evaporation. Air concentrations of highly chlorinated PCBs in the forest were more temperature dependent than those in the clearing, whereas no difference was observed for the less-chlorinated PCBs. Forest filtering may have enriched highly chlorinated PCBs in the forest soil relative to the soil in the clearing, resulting in a higher contribution of re-evaporation for highly chlorinated PCBs at the forest. Compared to measurements conducted a decade earlier at a nearby site, PCB air concentrations were generally less temperature dependent, indicative of a reduction in the contribution of re-evaporation in the region. Furthermore, a significant correlation was found between temperature dependence and degree of chlorination, which had not been apparent in the previous study. This is presumably because depuration from soils occurred slower for highly chlorinated PCBs, resulting in their relatively higher abundance in terrestrial surfaces and, therefore, higher contribution from re-evaporation. Contrasting with the PCBs, the temperature dependence of PBDE air concentrations did not differ between congeners or between forest and clearing site. This could be a result of different usage and emission history: PCBs were banned approximately three decades ago, whereas PBDEs are currently still in use. Consequently, the influence of primary emissions on air concentrations is expected to be more important for PBDEs than for PCBs.     

Factors influencing the soil-air partitioning and the strength of soils as a secondary source of polychlorinated biphenyls to the atmosphere

Soils are a major reservoir of persistent organic pollutants, and soil-air partitioning and exchange are key processes controlling the atmospheric concentrations and regional fate of pollutants. Here, we report and discuss the concentrations of polychlorinated biphenyls (PCBs) in soils, their measured fugacities in soil, the soil-air partition coefficients (K(SA)) and soil-air fugacity gradients in rural background areas of N-NE Spain and N-NW England. Four sampling campaigns were carried out to assess seasonal and daily variability and differences between sampling sites. K(SA) values were significantly dependent on soil temperature and soil organic matter quantity, and to a minor extent organic matter type. All the PCB congeners in the soil are close to equilibrium with the atmosphere at rural Ebro sites, but soil fugacities tend to be higher than ambient air fugacities in early and late summer, consistent with the influence of temperature on soil-air partitioning. Therefore, during warm periods, soils increment their strength as secondary sources to the atmosphere. The mixture of PCBs found in the atmosphere is clearly strongly influenced by the mixture of PCBs which escape from soil, with significant correlations between them (R(2) ranging between 0.35 and 0.74 and p-level <0.001 for the Ebro sampling sites). Conversely, the close-to-equilibrium to net sink status of rural UK sites, suggest a close coupling of air and soil concentrations, but it is not possible to elucidate the importance of these soils as secondary sources yet, and presumably there are still significant primary sources to the regional/global environment.     

Dietary exposure to short-chain chlorinated paraffins has increased in Beijing, China

Short-chain chlorinated paraffins (SCCPs) persist in the environment and bioaccumulate in biota and are under review by the Stockholm Convention on persistent organic pollutants. SCCP levels were measured semiquantitatively in pooled 24 h food composite samples from Chinese (n = 10), Korean (n = 10), and Japanese (n = 40) adults in the 1990 s and 2007-2009. In Japan, SCCPs were detected in 14 of 20 pooled samples in the 1990 s and 13 of 20 pooled samples in 2009. Between these two time points, the geometric mean (GM) of the dietary intake of total SCCPs per body weight was comparable in Japan (54 ng kg-bw(-1) day(-1) in the 1990 s and 54 ng kg-bw(-1) day(-1) in the 2000s). In Beijing, SCCP levels were elevated by 2 orders of magnitude from 1993 to 2009 (GM: 620 ng kg-bw(-1) day(-1) in 2009). The 95th percentile estimate of the dietary intake was 1200 ng kg-bw(-1) day(-1) (>1% of tolerable daily intake). In Seoul, no samples in 1994 contained detectable SCCP levels and only one sample in 2007 showed trace levels of SCCPs. Preliminary evidence on the significant increase in SCCP exposure in Beijing in 2009 warrants urgent investigations to refine dietary intake estimates by targeting food types and source identification.