Distribution of Short Chain Chlorinated Paraffins in Marine Sediments

Article pubs.acs.org/est

Distribution of Short Chain Chlorinated Paraffins in Marine Sediments of the East China Sea: Influencing Factors, Transport and Implications Lixi Zeng,†,‡ Zongshan Zhao,§ Huijuan Li,§ Thanh Wang,† Qian Liu,† Ke Xiao,† Yuguo Du,†,‡ Yawei Wang,*,† and Guibin Jiang† †

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China ‡ College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, Beijing 100049, China § Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China S Supporting Information *

ABSTRACT: Short chain chlorinated paraffins (SCCPs) are high production volume chemicals in China and found to be widely present in the environment. In this study, fifty-one surface sediments and two sediment cores were collected from the East China Sea to study their occurrence, distribution patterns and potential transport in the marginal sea. SCCPs were found in all surface sediments and ranged from 5.8 to 64.8 ng/g (dry weight, d.w.) with an average value of 25.9 ng/g d.w. A general decreasing trend with distance from the coast was observed, but the highest value was found in a distal mud area far away from the land. The C10 homologue was the most predominant carbon chain group, followed by C11, C12, and C13 homologue groups. Significant linear relationship was found between total organic carbon (TOC) and total SCCP concentrations (R2 = 0.51, p < 0.05). Spatial distributions and correlation analysis indicated that TOC, riverine input, ocean current, and atmospheric deposition played an important role in controlling SCCP accumulation in marine sediments. Vertical profiles of sediment cores showed that SCCP concentrations decreased from surface to the depth of 36 cm, and then slightly increased again with depth, which showed a significant positive correlation with TOC and chlorine contents (Cl %). The results suggest that SCCPs are being regionally or globally distributed by long-range atmospheric or ocean current transport.

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INTRODUCTION

mental data on SCCPs are very limited, largely due to the complexity of the analytical analysis in the quantification.15−20 CPs have been produced in the Europe Union (EU), U.S.A., Canada, China, and other countries. The production volumes of CPs for EU, U.S.A., and Canada were estimated to be between 7.5 and 11.3 kt/year in 2007. 21 In the EU and North America, SCCPs have been regulated owing to their potential environmental risk. By contrast, the production volume of CPs in China has continued to increase in recent years, up to 600 kt/year in 2007 and 1000 kt/year in 2009. 22 Although China is currently the largest producer and consumer of CPs in the world, information related to the environmental occurrence and distribution of SCCPs in environmental matrices in China still remain very limited. Our previous studies indicated that

As a group of industrial chemicals, chlorinated paraffins (CPs) are divided into short (SCCPs, C10−13), medium (MCCPs, C14−17), and long chain CPs (LCCPs, C18−30).1,2 They have been produced and used at large scales for the past several decades. CPs are extensively applied as plasticizers, flame retardants, sealants, and paints in various household and industrial products, and in other applications such as metalworking fluids and drilling.3 In many cases, CPs are used as additives in these materials increasing their ability to leach out into the environment by volatilization, abrasion, and dissolution.3−5 Previous studies have indicated that CPs can be found in water, atmosphere, soil, sediment, and biota around the world.6−10 Of the three groups, SCCPs are of the greatest concern as they have been shown to be the most toxic, volatile, water-soluble, and bioavailable.3,11−14 SCCPs are currently under review as candidate on persistent organic pollutants (POPs) in the Stockholm Convention. However, environ© 2012 American Chemical Society

Received: Revised: Accepted: Published: 9898

June 19, 2012 August 16, 2012 August 22, 2012 August 22, 2012 dx.doi.org/10.1021/es302463h | Environ. Sci. Technol. 2012, 46, 9898−9906

Environmental Science & Technology

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Figure 1. Sampling sites of surface sediments and sediment cores and regional ocean circulation patterns in the East China Sea. YSCC: Yellow Sea Coastal Current. KC: Kuroshio Current. TWC: Taiwan Warm Current. ZFCC: Zhejiang-Fujian Coastal Current. YDW: Yangtze Diluted Water. The mud areas are marked in gray and the DM represents the distal mud region.

pollutants from riverine discharges and deposition from atmospheric outflow of the Asian continent.31 Because of the unrestricted and wide usage of CPs in China, this complex mixture of industrial compound can be introduced into the coastal environment by river runoffs and atmospheric deposition, then partitioned from the water column and adsorbed onto the sediments because of their low solubility and high Kow.32 The Yangtze River Estuary (YRE) and inner shelf of the ECS can be important sinks of fine-grained sediments and their associated pollutants from the drainage basin. In this work, the concentrations and composition profiles of SCCPs were investigated in the depositional areas of the East China Sea. The objective is to examine the spatial and temporal distribution patterns of SCCPs in marine sediments on a regional scale, provide indications of pollution history recorded from the sediment cores in the inner and central continental shelf of the ECS, further to reveal the influencing factors related to the accumulation of SCCPs in marine sediments, and provide new information to understand their potential sources, transport pathways and fate in the marine environment.

relatively high concentrations of SCCPs were present in soils from wastewater irrigated farms and an e-waste dismantling area,23,24 as well as in sewage sludge from municipal sewage treatment plants,25 and aquatic organisms from a contaminated aquatic ecosystem.26 Recently, other studies also indicated the presence of SCCPs in sediments from the Pearl River delta and the Liaohe River basin in China.22,27 Harada et al.28 found the dietary intake of total SCCPs in selected 24 h food composite samples were elevated by 100-fold from 1993 to 2009 in China but found a very low intake in Japan and Korea, which might be related to the increasing production and consumption of CPs in China. The East China Sea (ECS) is one of the world’s largest shelf seas, and annually receives large amounts of contaminants from several major Chinese rivers, including the dominant Yangtze River, as well as the major local coastal rivers (e.g., Qiantang, Ou, Min Rivers). The environment of coastal areas from the ECS are significantly influenced by several main provinces, such as Shanghai, Zhejiang, and Fujian, which are highly urbanized and industrialized with electricity facilities, electronics manufacturing, printing, petrochemicals, and more.29 The ECS is downwind from the Chinese mainland and is therefore susceptible to the deposition of large amounts of atmospherically transported particles and associated pollutants.30 Overall, the coast of the ECS is one of the most developed regions in China, and the adjacent sea thus can act as receptor/sink of

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EXPERIMENTAL SECTION Background of Study Area. The ECS (Figure 1) has a broad but shallow shelf (width > 500 km, average water depth = 60 m), which is one of the largest river-dominated marginal 9899

dx.doi.org/10.1021/es302463h | Environ. Sci. Technol. 2012, 46, 9898−9906


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Figure 2. Spatial distributions of SCCP concentrations (A) and TOC (B) in surface sediments of study area in the East China Sea.

(ZFCC), which occurs during the northeast monsoon in winter, a large proportion of sediments from the Yangtze River can be transported southwards along the coast. Sediments are trapped in the inner shelf as blocked by the northward offshore Taiwan Warm Current (TWC), under formation of an elongated inner-shelf mud wedge from the Yangtze mouth into the Taiwan Strait.34 The mud area is broken at the mouth

seas in the world and one of the most dynamic coastal regions in terms of organic matter transport and sedimentation.33 The Yangtze River is the main source of sediments to the ECS, discharging 5 × 108 t of particulate matter per year, 2.4% of which is organic in origin.33 The Old Yellow River is also known to transport significant amount of material to the north of the ECS.34 Driven by the Zhejiang-Fujian Coastal Current 9900



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of the Qiantang River. Another distal mud area (DM) in this region is located in the central shelf of the ECS close to Cheju Island, which is about 400 km away from mainland China. The sediments in this region originate from the resuspension of tidal currents and winter and spring storms in the Old Yellow River estuary, which are then transported to the DM area by the Yellow Sea Coastal Current (YSCC).30 Sample Collection. The sampling locations are shown in Figure 1. A total of 48 surface sediment samples along nine transects across the ECS shelf (DH1 to DH8, and HE) were collected using a box-core sampler during a cruise conducted by “R/V Dong Fang Hong 2” in June, 2011. For the comparative investigation, to examine the influence of the potential pollution sources (e.g., cities, industrial areas, rivers), another three surface sediment samples (YRE, QR and MZ) were respectively collected from the locations adjacent to the YRE, Hangzhou Bay, and the coast of Zhejiang province during a cruise in August, 2011. Two sediment cores (Core-1 and Core2) from the distal and proximal mud areas were collected in April, 2011 at the central and inner shelf of the ECS, respectively. The sediment cores mainly consisted of clayey silt. The down-core variation of grain size was small, indicating a stable dynamic sedimentary environment in the sampling regions. The sediment cores were separated into 2 cm intervals along the length using a stainless steel cutter. All samples were kept in a shipboard refrigerator immediately at −4 °C after sampling and were thereafter transported to the laboratory where they were stored at −20 °C until analysis. Instrumental Analysis, Identification, and Quantification. Instrumental analysis was performed by a high-resolution gas chromatograph coupled with electron capture negative ionlow resolution mass spectrometer (HRGC/ECNI-LRMS, Agilent, USA). Briefly, the two most abundant isotopes of the [M−Cl]− cluster for individual CP congener groups with 5−10 chlorine atoms were monitored for quantification and confirmation. To ensure high instrumental sensitivity, SCCP and MCCP congeners were divided into four groups by the optimized combination of SCCP and MCCP formula groups (C10 and C15; C11 and C16; C12 and C17; C13 and C14) and subjected to analysis by four individual injections for each sample. For each injection, the corresponding SCCP and MCCP congeners were simultaneously monitored in the given retention time windows. Information on instrument analysis is described in detail available in our previous work.23 Identification of the different SCCP congener groups was conducted by monitoring selected [M−Cl]− ions, comparing retention time, chromatographic peak shapes and isotope ratio with those of standards.18 The MCCP congener interferences can be effectively reduced by a chemical calculation method previously described.23 The congener group abundance profiles were obtained by correcting the relative integrated signals for isotopic abundance and response factors. The quantification of SCCPs in sediment samples was based on the procedure described by Reth et al.19 to compensate the influence of chlorine contents on the total response factors between environmental samples and SCCP standards. A good linear correlation was obtained between the total response factors of SCCP standards and chlorine contents (R2 = 0.97). Therefore, a reliable quantification can be achieved even if the chlorine contents between the samples and the reference standards are different.

Article

RESULTS AND DISCUSSION

All concentrations were on a dry weight (d.w.) basis, and total organic carbon (TOC) normalized concentrations were also reported. SCCPs were found in all surface sediment samples in this study. For MCCPs, mainly C14 could be sporadically detected in a few samples at very low levels. Therefore, only SCCPs were reported and discussed below. Spatial Distribution of SCCPs and TOC in Surface Sediments. The concentrations of total SCCPs (∑SCCPs) in the ECS surface sediments ranged from 5.8 to 64.8 ng/g d.w., with an average value of 25.9 ng/g d.w. The concentrations were generally 1−3 orders of magnitude lower than those in sediments from Liaohe River Basin 27 and the Pearl River Delta in China, 22 and also much lower than those in marine sediments from Barcelona in Spain (0.21−1.17 μg/g, d.w.), 35 but somewhat equivalent to those in Ontario lake sediments (average 49 ng/g, d.w.) 36 and Canadian Arctic lake sediments (4.52 ng/g, d.w.).37 The corresponding TOC normalized concentrations were in range of 1.7−7.5 μg/g TOC, while the chlorine contents of SCCPs in all surface sediment were between 58.5 to 61.7%. The detailed individual and total concentrations of SCCP congeners, chlorine contents (Cl%) and total organic carbon (TOC) contents at each site are listed in Supporting Information Table SI-1. The spatial distributions of SCCPs and TOC normalized SCCP concentrations in the ECS surface sediments are shown in Figure 2A and Supporting Information Figure SI-1, respectively. Relative higher levels of SCCPs were found in the nearshore areas of the ECS, with an offshore decreasing trend toward the outer shelf, suggesting a direct influence of riverine inputs and the proximity to land-based sources in the coastal ECS. The concentration of SCCPs in the sediments of the Yangtze River estuary (YRE) and the Hangzhou Bay (QR) was up to 41.9 and 42.4 ng/g d.w., respectively. The relatively high SCCP concentrations could be attributed to the impact from two large coastal rivers, the Yangtze and Qiantang rivers. A higher concentration of SCCPs (61.0 ng/g d.w.) was observed as site MZ, which is located in the coast of the Zhejiang province, indicating that SCCP levels in coastal sediments could be associated with the regional economic development. On the whole, the concentrations of SCCPs were generally higher at the sampling locations closer to land than those in the open sea in the ECS. For example, the concentration of SCCPs were more than two times higher in the coastal areas at site DH8-1 (33.1 ng/g d.w.) compared to the distant site DH8-3 (15.0 ng/g d.w.) along the transect DH8. The results indicated that high residue levels of SCCPs were constrained in the inner-shelf mud areas, and the mainland was probably the major source to the ECS coastal environment. Along the transect DH1, SCCP concentration gradually increased with distance from the edge to the outer areas, with the highest value at site DH1-7 (64.8 ng/g d.w.). Along the transect DH2, SCCP concentrations was found first to decrease with distance from land (from DH2-1 to DH2-5), with the lowest value at site DH2-5 (8.5 ng/g d.w.), and then increase with the distance from land (from DH2-6 to DH2-8), with the highest value at site DH2-7 (60.3 ng/g d.w.). Along the transect DH3, SCCP concentration showed a slightly decreasing trend from DH3-1 (21.9 ng/g d.w.) to DH3-8 (15.9 ng/g d.w.). Furthermore, along the transect DH4, SCCP concentrations showed a clear decreasing trend from the inner shelf to the 9901



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open sea, with concentrations from 39.1 ng/g d.w. at DH4-1 to 5.8 ng/g d.w. at DH4-8. The sampling sites at DH1-7 and DH2-7, which lay in the DM region of the ECS central shelf, showed the highest concentrations in the study area. The other sites in the DM region also showed comparable or higher concentrations than those in inner-shelf mud areas. The DM region is a modern depositional center in the ECS and is about 400 km away from the assumed main pollution source, the Chinese mainland.30 The sediments in the DM region are mainly from the Old Yellow River estuary through long-distance transport by the YSCC,38 whereas sediment contribution from the Yangtze River to the DM region is very small due to the obstruction by Taiwan Warm Current (TWC).38 Because the Yellow River changed course to its current Bohai Sea estuary before China started to industrialize, the sediments from the Old Yellow River estuary to the DM region contain only minor anthropogenic pollutions.30 When the northwesterly winds prevail, pollutants sorbed to aerosol from north China 39 and east Asian can be transported to the northern Pacific Ocean.40 The DM region of the ECS is downwind of the Chinese mainland and the pathway for outflowing continental pollutants to the northern Pacific, leading to a large deposition of atmospheric particles in this region.30 Therefore, the high SCCP concentration levels in the DM region should be considered to mainly originate from atmospheric deposition. The results implied that the spatial distribution of SCCPs in the transect DH1 is mainly impacted by the YSCC and atmospheric deposition in the DM region. For transect DH2, the spatial distribution of SCCPs is more regulated by riverine input and atmospheric deposition in the DM region. Moreover, for transect DH3 to DH4, the decreasing trend with distance from land show that the riverine input might be the major resource of SCCPs to the inner shelf. TOC in the ECS surface sediments were in the range of 0.33% and 0.88% (Supporting Information Table SI-1). The coastal mud and DM regions have relatively higher contents of TOC in the sediments than other areas. The spatial distribution of TOC in surface sediments (Figure 2B) showed a resemblance to that of SCCP concentrations, which is in agreement with the widely accepted view that TOC is a key factor influencing the accumulation of SCCPs in the sediment. Correlation analysis indicated significant linear relationships between the TOC and SCCP concentrations (R2 = 0.51, p < 0.05, see Supporting Information Figure SI-3). SCCP Congener Patterns in Surface Sediments of the ECS and YRE and the Implication for Transport. The SCCP congener group profiles in the YRE, DH2-1, DH2-3, DH2-5, and DH2-7 and the comparison of chlorine congener group abundance among the five sites are shown in Figure 3. Among the carbon congener group abundance profiles, we found that the C10 homologue was the most predominant carbon chain group, accounting for 42.3−57.7% of the SCCPs, followed by C11 homologue at about 26.3−31.1%, C12 homologue at about 6.8−16.3% and C13 homologue at about 4.4−12.9%. When categorized by the chlorine congener groups, the 5Cl, 6Cl and 7Cl groups were the most abundant ones. The QR and MZ sites showed a quite similar composition profile to the YRE, and the other transects in the study area also showed a similar composition profile to the DH2. The distribution patterns in marine sediments are similar to those found in the atmosphere from north China41 and river sediments from the Liaohe River Basin,27 which were

Figure 3. SCCP congener group abundance profiles at YRE, DH2-1, DH2-3, DH2-5, and DH2-7 sites (A−E), and comparisons of chlorine congener group abundance of YRE with other sites along the representative transect DH2 (F). The percentages above the plots are the total relative abundance for each carbon chain group.

dominated by shorter SCCP homologues with 10 and 11 carbons. However, the profiles were noticeably different from those generally found in other environmental matrices in China such as soil,22−24 sewage sludge,25 and other sediments from local regions including the Pearl River Delta 22 and a typical effluent-receiving lake. 26 These comparative results imply that the shorter chain and lower chlorinated congeners, which should be more volatile and water soluble, might more easily migrate to remote regions or marine environments by longrange atmospheric or waterborne transport. There were some differences for the SCCP congener group profiles among YRE and DH2 sites as seen in Figure 3. For YRE site, the most and second most abundant chlorine congener groups were 7Cl and 8Cl, whereas for DH2-1, DH23, and DH2-5 sites, the predominant congener groups were 5Cl and 6Cl. The long chain C12 and C13 groups accounted for relatively higher abundances at YRE compared to DH2-1, DH2-3, and DH2-5 sites. For the transect DH2, moreover, the most and second most abundant chlorine congener groups for DH2-7 site in the DM region were 6Cl and 7Cl, and the longer chain C12 and C13 groups also accounted for a higher fraction than the other DH2 sites. Some higher chlorinated congener groups 9Cl and 10Cl can be observed in the DM region, which may be mainly attributed to atmospheric deposition rather than riverine input. On the basis of the carbon chain group patterns, the abundance of shorter chain congener groups gradually increased with sampling site from YRE to DH2-5. The relative abundance of C10, C11, C12, and C13 homologue groups were 46.0%, 26.3%, 16.3%, and 11.4% at YRE, and then shifted to 57.7%, 31.1%, 6.8%, and 4.4% at DH2-5, respectively. Moreover, as shown in Figure 3F, the lower chlorinated 5Cl and 6Cl groups generally increased, while the higher 9902



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Figure 4. Vertical distributions of total SCCP concentrations and degree of chlorination with increasing depth in the sediment core-1 and core-2 from the distal and coastal mud areas of the ECS.

Figure 5. Variation in SCCP carbon chain abundances with sampling depth in sediment slices of core-1 and core-2 from the distal and coastal mud areas of the ECS.

historical records of SCCP pollutions from the riverine input and atmospheric transportation. Figure 4 shows the vertical distributions of ∑SCCP concentrations and degree of chlorination with depth in the two sediment cores. The detailed individual and total concentrations of SCCP congeners, degree of chlorination and TOC% are listed in Supporting Information Table SI-2 and SI-3, respectively. The core-1 from the central-shelf mud showed significantly higher concentrations (15.9−46.5 ng/g d.w., or 2.5−6.1 μg/g TOC) than the core-2 from the innershelf mud (4.4−25.7 ng/g d.w., or 0.8−3.1 μg/g TOC) (Supporting Information Figure SI-2). There could be two possible reasons responsible for the apparent concentration difference between the two sediment cores. One is that atmospheric input of SCCPs to the central-shelf mud may be higher than riverine input to the inner-shelf mud. The other is the sedimentation rate in the inner shelf is higher than that in the central shelf.43 The high sedimentation rate may play a “dilution effect” role on SCCP contents in the inner-shelf sediment core. As shown in Figure 4, an obvious decreasing concentration trend with sampling depth to the middle and lower sediment segments (0−40 cm) can be seen in both sediment cores. However, at the deeper sediment segments (41−56 cm), the cores showed a slightly increasing concentration trend. The high SCCP concentrations in the upper sediment segments

chlorinated 7Cl, 8Cl and 9Cl groups correspondingly decreased with site from YRE to DH2-5. For the other transects, SCCPs congener groups profiles showed a similar shift toward the shorter chain and lower chlorinated congeners with distances away from the land. The variations of congener group profiles with distance from land are probably related to the differences in the physicochemical properties and environmental behaviors among different congeners. Hilger et al.32 studied the effects of chain length on log Kow of SCCPs and found that log Kow value increased linearly with increasing carbon atom numbers. Drouillard et al.42 have shown that vapor pressures (VPs) of selected SCCP congeners tended to decrease with increasing carbon chain length and degree of chlorination. This work further suggests that shorter chain and lower chlorinated congeners have stronger transport abilities than longer chain and higher chlorinated congeners, probably because of their higher volatility and water solubility.23 Indications for the Temporal Trends of SCCPs from Marine Sediment Cores. The inner-shelf coastal mud of the ECS is an important sink of sediment-associated pollutants from direct riverine inputs and land-originated surface runoffs, while the central-shelf distal mud is an ideal place for deposition of airborne contaminants transported mainly from China. In this study, two sediment cores were taken from the inner- and central-shelf mud to respectively reconstruct the 9903



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could coincide with the rapid increasing production and usage of technical CPs in recent years in China, and is also consistent with previous studies from other areas in China.22,26 The relatively high concentrations at the bottom layers might be attributed to the large depositional flux at those time stages. 30 The results could imply that SCCPs can be persistent for at least several decades in the anaerobic marine sediment environment. TOC in core-1 and core-2 were in the range of 0.52−0.85% and 0.57−0.82%, respectively (Supporting Information Table SI-2,3). The chlorine contents of SCCPs were higher in core-1 than core-2 and were in the range of 60.6−61.6% and 58.3− 60.1%, respectively. As shown in Figure 4, the chlorine content of SCCPs generally decreased with the depth in both sediment cores. Regression analysis indicated SCCP concentrations have significantly positive linear relationships with the chlorine contents (R2 = 0.46 and 0.77 for core-1 and −2, p < 0.05, see Supporting Information Figure SI-4). Moreover, significant correlations were also observed between SCCP concentrations and TOC in the two sediment cores, further confirming that TOC is a key factor controlling the accumulation of SCCPs in marine sediments of the ECS (R2 = 0.43 and 0.53 for core-1 and −2, p < 0.05, see Supporting Information Figure SI-3) SCCP Congener Group Patterns in Marine Sediment Cores. The carbon congener compositions and their relative abundance variation in sediment cores with depth were also examined. As shown in Figure 5, in most sediment slices, C10 were the most abundant congener groups, followed by C11, C12, and C13 congener groups, which were similar to the congener patterns in surface sediments. The abundance of C10 and C11 congener groups were generally higher in the upper segment than in the lower segment, correspondingly, the percent contributions of C12 and C13 congener groups were higher in the lower segment (0−40 cm). This change trend was more obvious in core-2 from the coastal mud area. The variations in SCCP congener abundance profiles in sediment core slices with different depth were further illustrated in Supporting Information Figure SI-5. The decrease of short chain homologues and enrichment of long chain homologues with depth were consistent with the recent finding in a dated sediment core from the Pearl River Delta,22 further indicating that the patterns of CP mixture used in recent times might be different from those used in early decades in China. However, the transport behavior and environmental persistence of different SCCP congeners could also influence this distribution pattern between the upper and the lower sediment core slices. As described above, the chlorine contents of SCCPs showed a decreasing trend with increasing depth in marine sediment cores. This observation might be attributed to the dechlorination of higher chlorinated congeners to lower chlorinated congeners during the aging of the sediments in anaerobic environment,22,36 implying that potential microbial mediated degradation of SCCPs might take place in similar manner in marine sediments. This study lays a foundation for further understanding the environmental occurrence and fate of SCCPs in a marginal sea impacted by river-dominated inputs and atmospheric depositions. However, whether the main SCCP inputs are through long-range transport via atmosphere or ocean current and if their distribution patterns are similar in other oceanic environments need further investigation.

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ASSOCIATED CONTENT

S Supporting Information *

Detailed procedures on sample extraction and cleanup, TOC analysis, quality assurance and quality control (QA/QC), detailed concentrations of ∑SCCPs and congeners, degree of chlorination and TOC in surface sediments (Table SI-1), core1 (Table SI-2) and core-2 (Table SI-3), distributions of TOC normalized SCCP concentrations in the surface sediments and sediment cores of the ECS (Figure SI-1, SI-2), the correlations between SCCP concentrations and TOC% in surface sediments, core-1 and core-2 (Figure SI-3), the correlations between SCCP concentrations and degree of chlorination in core-1 and core-2 (Figure SI-4), and variation in SCCP congener abundance profiles with sampling depth in sediment slices of core-1 and core-2 (Figure SI-5). This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*Address: State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China. Tel: 8610-6284-9334. Fax: 8610-6284-9339. Email: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was jointly supported by the National Natural Science Foundation (21007078, 21007062, 20890111, 20921063), the China Postdoctoral Science Foundation (2012M510052) and the President Fund of GUCAS (Y25101BY00). We thank the National Basic Research Program of China (2010CB428901) and National Natural Science Foundation of China (Open Cruises of the East China Sea, 2011) for the samples.

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REFERENCES

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Distribution of Short Chain Chlorinated Paraffins in Marine Sediments

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