Distribution characteristics of PCBs in the sediments of the lower Nakdong River, Korea

Efficient biostimulation of microbial dechlorination of polychlorinated biphenyls by acetate and lactate under nitrate reducing conditions: Insights into dechlorination pathways and functional genes

Microbial-catalyzed reductive dechlorination of polychlorinated biphenyls (PCBs) is largely affected by the indigenous sediment geochemical properties. In this study, the effects of nitrate on PCB dechlorination and microbial community structures were first investigated in Taihu Lake sediment microcosms. And biostimulation study was attempted supplementing acetate/lactate. PCB dechlorination was apparently inhibited under nitrate-reducing conditions. Lower PCB dechlorination rate and less PCB dechlorination extent were observed in nitrate amended sediment microcosms (T-N) than those in non-nitrate amended microcosms (T-1) during 66 weeks of incubation. The total PCB mass reduction in T-N was 17.6% lower than that in T-1. The flanked-para dechlorination was completely inhibited, while the ortho-flanked meta dechlorination was only partially inhibited in T-N. The 7.5 mM of acetate/lactate supplementation recovered PCB dechlorination by resuming ortho-flanked meta dechlorination. Repeated additions of lactate showed more effective biostimulation than acetate. Phylum Chloroflexi, containing most known PCB dechlorinators, was found to play a vital role on stability of the network structures. In T-N, putative dechlorinating Chloroflexi, Dehalococcoides and RDase genes rdh12, pcbA4, pcbA5 all declined. With acetate/lactate supplementation, Dehalococcoides grew by 1-2 orders of magnitude and rdh12, pcbA4, pcbA5 increased by 1-3 orders of magnitude. At Week 66, parent PCBs declined by 86.4% and 80.9% respectively in T-N-LA and T-N-AC compared to 69.9% in T-N. These findings provide insights into acetate/lactate biostimulation as a cost-effective approach for treating PCB contaminated sediments undergoing nitrate inhibition.

Chlorinated pesticides and PCB residues in the Egyptian Western Desert oases sediments

This preliminary investigation aimed to detect concentrations of chlorinated pesticides and PCBs in 40 sediment samples from three desert oases located in Kharga, Dakhla and Farafra in western Egypt. The residues of 18 PCBs and 16 chlorinated pesticides were measured by GC-MS/MS (SRM) method. The results showed that PCBs and pesticides were present in all studied samples. The concentrations of individual PCBs ranged from undetected to 3.99 ng/g dw in all these sediment samples. The total residue of pesticides (ng/g, dry weight) in sediment samples also varied from 5.18 to 25.92, 5.41 to 29.49, and 5.93 to 24.19 ng/g dw for the Kharga, Dakhla and Farafra Oases, respectively. The concentrations of PCBs and chlorinated pesticides detected in these oasis sediments were lower than that reported for other worldwide locations. According to the recorded concentrations in this baseline study of PCBs and total DDTs, the results revealed the minimal risks to organisms and people in the studied area according to the Effects Range-Low (ERL) and Effects Range-Median (ERM) guideline values.

Instrumental and bioanalytical characterization of dioxin-like activity in sediments from the Yeongsan River and the Nakdong River estuaries, South Korea

In the present study, we investigated the contamination status of dioxin-like chemicals (DLCs) and potential toxic effects associated with river and coastal sediments from two large estuaries of South Korea. Sediments collected from the Yeongsan River and the Nakdong River estuaries were analyzed for several DLCs, including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), coplanar polychlorinated biphenyls (co-PCBs), and polycyclic aromatic hydrocarbons (PAHs). Greater concentrations of target DLCs (except for PCDDs in Nakdong River) were found in the inland creeks with decreasing trends towards estuarine and coastal areas in both regions. The result indicated that the elevated DLCs were attributable to the surrounding land use activities, such as point sources of industrial and municipal areas from the inland regions. Principal component analysis and positive matrix factorization model revealed that major sources of PCDD/Fs and PAHs in sediments were fly ash and dust, and petroleum and diesel emission, respectively. The dioxin-like activities of the sediments ranged from 0.98 to 88% of the maximal induction elicited by 2,3,7,8-tetrachlorodibenzo-p-dioxin, which generally explained the sedimentary contamination by the target DLCs. Dioxin-like activity in sediments from the artificial lake and inland creek of the Nakdong River Estuary was mostly explained by the targeted DLCs (~75%). However, the contribution of known DLCs from the sediments of the Yeongsan River Estuary was relatively low (~35%) compared to that of the Nakdong River Estuary, suggesting the presence of unknown DLCs in sediments. Overall, the distribution of DLCs quite varied by region, generally reflecting the difference in the surrounding land use activity. In the future, it is needed to study the distribution, sources, and potential ecological effects of unknown toxic substances in coastal sediments.

Spatial distribution and source identification of traditional and emerging persistent toxic substances in the offshore sediment of South Korea

While the coastal pollution of persistent toxic substances (PTSs) has been widely documented, information on offshore environments remains limited. Here, we investigated the spatial distribution and sources of PTSs in the offshore sediments (n = 34) of South Korea. Sediment samples collected from the Yellow Sea (n = 18), the South Sea (n = 10), and the East Sea (n = 6), in 2017-18 were analyzed for a total of 71 PTSs. Target compounds include 31 PCBs, 15 PAHs, 9 emerging PAHs (e-PAHs), 10 styrene oligomers (SOs), and 6 alkylphenols (APs). Sedimentary PCBs showed relatively low concentrations with no significant difference across the three seas (0.16-6.9 ng g^-1 normalized organic carbon, OC). Low-chlorinated PCBs (tri- and tetra Cl-CBs) were predominant (mean: 77%), primarily indicating atmospheric inputs. PAHs widely accumulated in the three seas with low to moderate level (22-250 ng g^-1 OC), and dominated by high molecular weight PAHs (4-6 rings). PMF analysis revealed coast-specific PAHs sources; i.e., originated from mainly coke production (77%) in the Yellow Sea, vehicle emissions (68%) in the South Sea, and fossil fuel combustion (49%) in the East Sea. SOs showed significant contamination than other PTSs, with elevated concentrations in the Yellow Sea (mean: 350 ng g^-1 OC). APs showed a similar regional distribution to SOs, but concentrations were much lower (mean: 17 ng g^-1 OC). SOs and APs seemed to be introduced from rivers and estuaries on the west coast of Korea, where industrial and municipal activities are concentrated, then might be transported to offshore through tide or currents. Overall, the novel data presented for various PTSs in offshore Korean sediments warrant the necessity of a long-term monitoring effort and urgent management practice to protect marine ecosystem.

Unintentionally produced polychlorinated biphenyls in pigments: An updated review on their formation, emission sources, contamination status, and toxic effects

The formation, emission, environmental occurrence, and potential adverse effects of unintentionally produced polychlorinated biphenyls (PCBs) in pigments are reviewed, providing a comprehensive and up-to-date picture on these pollutants. PCBs are typically formed during manufacturing of organic pigments that involve chlorinated intermediates and reaction solvents, rather than those of inorganic pigments. Concentrations and profiles of PCBs vary greatly among pigment types and producers, with total PCB levels ranging from lower than detection limits to several hundred ppm; major components can be low-chlorinated (e.g., CB-11) or high-chlorinated congeners (e.g., CB-209). Pigment-derived PCBs can be released into the environment through different steps including pigment production, application, and disposal. They can contaminate atmospheric, terrestrial, and aquatic ecosystems, and then affect organisms living there. This situation garners scientific and public attention to nonlegacy emissions of PCBs and suggests the need for appropriate monitoring, management, and abatement strategies regarding these pollutants.

Distribution characteristics and environmental fate of PCBs in marine sediments at different latitudinal regions: Insights from congener profiles

Sediments were sampled from Hangzhou Bay (HB), the South China Sea (SCS), and Antarctica (AZ) to better understand the distribution characteristics and environmental fate of polychlorinated biphenyls (PCBs) at different latitudes. Numerous PCB congeners (68) were detected among the sampling sites, supporting the ubiquity of PCB congeners. High and low chlorinated congeners dominated the PCB profiles of AZ and SCS, respectively, whereas the PCB homologues were evenly distributed in the HB. As a fraction of low chlorinated PCBs originates from an exogenous input, the low mean ratios of ∑Tetra-CBs to ∑PCBs and ∑Tetra-CBs to the sum of ∑Tri- and ∑Di-CBs suggest that microbial transformation of PCBs is weak in marine surface sediments, if any occurs at all. Furthermore, PCB contamination levels in marine sediments may be primarily influenced by latitude rather than pollution sources. Thus, the findings of this study suggest that Antarctica is becoming a prospective hotspot for PCBs.

The distribution characteristics of polychlorinated biphenyls (PCBs) in the surface sediments of Ross Sea and Drake Passage, Antarctica: A 192 congeners analysis

A total of 23 sediment samples are collected from Ross Sea and Drake Passage to investigate the distribution characteristics of polychlorinated biphenyls (PCBs) in the Antarctic marine sediments. Over 51 kinds of PCBs are detected through exhaustive searches using multiple reaction monitoring system. The results show that the concentration of individual PCB congener and total PCBs vary greatly among sampling sites, ranging from not detected to 49.75 ng g^-1 and 3.77 to 246.86 ng g^-1, respectively. The average PCBs level in Ross Sea is ten times higher than that in Drake Passage. Two different homologues, hexa- and tetra-CBs, give high contributions to ∑PCBs level in most samples from Ross Sea and Drake Passage, respectively. Our results support that the marine sediments might be an important sink for PCBs. Besides, the biological pump and the primary productivity might be responsible for the distribution differences of PCBs between Ross Sea and Drake Passage.

Occurrence of polychlorinated diphenyl sulfides (PCDPSs) in surface sediments and surface water from the Nanjing section of the Yangtze River

Polychlorinated diphenyl sulfides (PCDPSs) are dioxin-like compounds that could induce various adverse effects to organisms. However, little is known about the occurrence of PCDPSs in the riverine environment. In the present study, the concentrations of twenty-one types of PCDPSs in the surface sediments and in surface water from the Nanjing section of the Yangtze River were examined. A total of 19 types of PCDPSs were detected and ∑PCDPSs concentrations in surface sediment and surface water ranged from 0.10 to 6.90 ng/g and 0.18 to 2.03 ng/L, respectively. The 2,2',4,4',5-penta-CDPS was the dominant congener in sediment (19.9%) and 2,2',3,3'-tetra-CDPS was the most abundant congener in water (12.2%). The tetra-CDPSs were the dominant congeners both in sediment and in water. Compared with sediment, the percentage of lower chlorinated PCDPSs in water increased distinctly. Source analysis revealed that the PCDPSs in the sediment and in the water mainly came from chemical wastewater rather than domestic sewage. There was a significant linear correlation between ∑PCDPS concentrations and sediment TOC contents, while no linear correlation existed between ∑PCDPS concentrations and water DOC contents. This study demonstrated the prevalent contamination by PCDPSs in sediments and in water from the Nanjing section of the Yangtze River.

Status, distribution and ecological risk of organochlorines (OCs) in the surface sediments from the Ravi River, Pakistan

Organochlorines (OCs) including organochlorine pesticides (OCPs) and polychlorinated biphenyl (PCBs) were analyzed in surface sediments from the Ravi River, Punjab, Pakistan. Among the OCPs, hexachlorocyclohexane (HCHs), dichlorodiphenyltrichloroethane (DDTs) and chlordane (cis- and trans-) were most abundant and their concentrations were ranged from n.d to 16.0 ng g(-1), 1.5 to 58.5 ng g(-1) and n.d to 29.0 ng g(-1), respectively. Concentrations of Σ31PCBs ranged from 4.6 to 424.3 ng g(-1) with a mean value of 48.9 ng g(-1). In general, the concentrations of all studied organochlorines (OCs) in sediments collected from the sampling sites in the vicinity of industrial areas were higher than those from the agricultural areas. Compositional analyses of PCBs indicated that penta- and tetra-PCBs homologues were dominant which was consistent with the previous studies. Compared with other areas around the world, levels of OCs in sediments from the Ravi River were within the range, but were found to be much higher than previously reported from Pakistan. According to established sediment quality guidelines (SQGs), screening-level risk assessment of OCPs and PCBs suggested that they have a potential for adverse effects on benthic organisms.

Assessment of trace pollutants in Korean coastal sediments using the triad approach: a review

Here we summarize and review the previous efforts on sediment assessment together with major scientific findings that were conducted in the Korean coastal waters since late 1990s. Towards integrated triad analysis, sediment data (>1700 samples) reported from the Korean coasts were collected and reviewed of which data collectively includes three components of chemical, toxicological, and ecological measures. First, the chemistry data suggested widespread and historic distribution of sedimentary pollutants along the Korean coasts. Spatial distributions suggested that their sources were independent of each other, while some localized areas (highlighted for Lake Shihwa, Masan Bay, and Ulsan Bay) and zones with extremely high pressures of certain pollutants were also identified. The mass balance analyses and/or direct correlations linking triad components reflected a general agreement between endpoints. The benthic community responses given by species occurrence and diversity also reflected the type and degree of sediment contamination, however, could not be fully explained by the known target chemicals. Overall, the triad assessment of trace pollutants in Korean coastal sediments seemed to be useful and much powerful when all the components are fully addressed.

Hexabromocyclododecanes in crucian carp and sediment from the major rivers in Korea

The concentration of hexabromocyclododecanes (HBCDs) was measured in crucian carp muscles and eggs and in surrounding sediments collected from the 3 major rivers in Korea. HBCDs were detected in all carp and sediment samples, indicating widespread contamination of this area by HBCD flame retardants. The ∑HBCD (sum of α-, β-, and γ-HBCDs) concentrations ranged from 0.19 to 13 ng g(-1)dry wt in sediments, 1.7 to 7.2 ng g(-1)lipid wt in carp eggs, and 4.8 to 6.6 ng g(-1)lipid wt in the muscle of carp. The α-diastereomer predominated in the crucian carp and γ-diastereomer predominated in sediments, accounting for 76% and 77% to the ∑HBCD, respectively. The ∑HBCD concentrations in carp and sediment samples collected along the rivers were higher than those in samples collected from an isolated pond, suggesting that the rivers are likely contaminated by HBCDs from the upstream or the environment surrounding the rivers. The diastereomer ratios in carp were different from those in commercial mixtures due to the enrichment of α-diastereomer in carp. The origin of this transition, however, is yet not known, since various transformation processes can lead to a change from the diastereomer ratio in commercial mixtures to that observed in the environment.

Distributions of polychlorinated biphenyls in the Daliao River estuary of Liaodong Bay, Bohai Sea (China)

The distributions of 41 polychlorinated biphenyls (PCBs) were determined in the aqueous phase, suspended particulate matter (SPM), and sediment of the Daliao River estuary in Liaodong Bay, Bohai Sea (China). The total PCB concentrations ranged from 5.51 to 40.28 ng L(-1) in the surface water, from 6.78 to 66.55 ng L(-1) dry weight in the SPM, and from 0.83 to 7.29 ng g(-1) dry weight in the sediment. The PCB concentrations in water, SPM, and sediment were moderate relative to those reported for other estuary and marine systems around the world. Sedimentary PCB concentrations decreased offshore due to the active deposition of laterally transported river-borne particles. The predominance of the highly chlorinated congeners for the water, SPM, and sediment samples are an indication of either a lack of degradation or the presence of nearby or recent releases into the environment.

Occurrence, possible sources, and temporal trends of polychlorinated dibenzo-p-dioxins and dibenzofurans in water and sediment from the lower Yangtze River basin, Jiangsu and Shanghai areas of Eastern China

The concentrations, compositional profiles, and possible sources of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) in water column and surface sediment samples from the lower reaches of the Yangtze River were investigated, and the potential risks posed by these chemicals were evaluated. Concentrations of the 17 2,3,7,8-substituted PCDD/PCDF in the water and sediment samples ranged from 0.45 to 10.0 pg TEQ/L (mean 2.34 pg TEQ/L) and from 0.31 to 51 pg TEQ/g dw (mean 5.25 pg TEQ/g dw), respectively. Water and sediments from the Nanjing-Nantong sections of the Yangtze River were found to have elevated PCDD/PCDF levels, and the PCDD/PCDF TEQ concentrations in 13 sediment samples exceeded the probable effect levels (PEL), above which adverse biological effects are likely. Multivariate statistical analysis indicated that the principal PCDD/PCDF contamination source for the water and sediment was the production and use of pentachlorophenol (PCP) or sodium pentachlorophenate (PCP-Na). PCDD/PCDF concentrations were stable over time near the Yangtze River Estuary but had increased sharply in recent decades in the Nanjing-Nantong section, which will have been related to the growth in industrial activities and other anthropogenic PCDD/PCDF sources. Total organic carbon (TOC) and PCDD/PCDF concentrations correlated significantly (R=0.474, P<0.01), suggesting that TOC plays an important role in the transport and re-distribution of PCDD/PCDF in the Yangtze River basin.

Polychlorinated biphenyl congeners in river sediments: distribution and source identification using multivariate factor analysis

To assess the level of polychlorinated biphenyl (PCB) contamination and identify their sources, surface sediments were collected from selected locations along Nakdong River, Korea, and analyzed for 209 PCB congeners using high-resolution gas chromatography/high-resolution mass spectroscopy. PCB levels ranged from 0.124 to 79.2 ng/g dry weight (coplanar PCBs 0.295 to 5720 pg/g dry), which were similar to those of three other major rivers (Han, Geum, and Youngsan rivers) in Korea but slightly lower than those in neighboring countries. Regarding homologue composition, tetra-CBs were most abundant in most samples, but some samples with much higher PCBs concentrations had relatively lower proportions of tetra-CBs and higher proportions of penta- to hepta-CBs. To identify the sources of PCBs in sediment samples, principal component analysis/absolute principal component scores (PCA/APCS), positive matrix factorization (PMF), and multiple linear regression (MLR) were used with the congener composition of aroclors (1242, 1248, 1254, and 1260) and the flue gas of waste incinerators (data obtained from a previous article) as source profiles. Results showed that the three models showed similar source apportionments. Most sediment samples with lower PCB concentrations had higher proportions of incineration-derived materials, and some sediment samples with much higher PCB concentrations had higher proportions of aroclor 1260. This occurred because many industrial facilities, such as landfill leachate-treatment facilities, were gathered around sampling points with high PCB concentrations, and high-chlorinated PCBs are more stable in the elution process of landfill leachate than the incineration process. PCB concentrations estimated by APCS, PMF, and MLR were similar to the measured values with coefficients of determination ranging from 0.77 to 0.99.

Characterization of polychlorinated biphenyls and brominated flame retardants in sediments from riverine and coastal waters of Surabaya, Indonesia

A total of 33 surficial sediments from riverine and coastal waters from Surabaya, Indonesia were analyzed for PCBs and BFRs. Concentrations of PCBs (62 congeners), PBDEs (14 congeners) and HBCDs (3 isomers) varied from <DL-420, <DL-35 and <DL-5.4 ng g(-1)dw, respectively. Higher concentrations of these compounds were found in riverine than coastal sediments. Their levels and distribution were influenced by proximity to the point sources and TOC. The predominant congeners were CB-153, -28, -138, -149, -180, -33 and BDE-209, -207, -206, -197, -196, -183, -99, -47 for PCBs and PBDEs, respectively, and γ-isomer for HBCDs. Debromination of BDE-209 might be taking place producing lower toxic congeners in sediment. Levels of PCBs in riverine sediments were comparable with some polluted areas worldwide, but PBDEs and HBCDs were lower. Hazard assessment of PCBs indicated possible toxic potential, particularly in areas close to point sources.

Occurrence and possible sources of polychlorinated biphenyls in surface sediments from the Wuhan reach of the Yangtze River, China

Twenty-seven surface sediment samples were collected from the mainstream and eight tributaries of the Wuhan reach of the Yangtze River, China, in 2005, in order to assess the distribution, possible sources, and potential risk of polychlorinated biphenyls (PCBs) in the environment. The total concentrations of PCBs (the sum of 39 congeners) ranged from 1.2 to 45.1 ng g(-1) dry weight, with a mean value of 9.2 ng g(-1). Sediment samples with the highest PCB concentrations came from the tributary sites, which are closer to PCB sources. Conversely, PCB concentrations in the sediment from the mainstream sites of Yangtze River were relatively low. The observed PCB levels were higher than those found in the sediments of other rivers in China, but lower than those in river sediments from other urban areas and harbors around the world. Low-chlorinated PCBs, dominated by tetra-PCBs and penta-PCBs, were identified as being prevalent in the surface sediments. Correlation analyses between the PCBs and the geochemistry and heavy metal content of the sediments suggest that the washing of these compounds from the land into the river by floods and heavy rains, or industrial wastewater and domestic sewage, may be the major sources of the PCBs. According to established sediment quality guidelines, the risk of adverse biological effects from the levels of PCBs recorded at most of the studied sites should be insignificant, although the higher concentrations at other sites could cause acute biological damage.

Distribution of persistent organochlorine residues in sediments from the Songhuajiang River, Northeast China

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in surface sediments from 10 sampling sites of the Songhuajiang River were analyzed to evaluate their potential pollution and hazards. Gas chromatography equipped with a 63Ni electron capture detector (GC-ECD) and gas chromatography/mass spectrometer (GC/MS) methods were used, respectively. The total concentrations of 13 OCPs varied from 4.26 to 18.45 ng g(-1). Sigma HCH (alpha-HCH, beta-HCH, delta-HCH, gamma-HCH), sigma DDT (p, p'-DDE, p, p'-DDD, o,p'-DDT, p, p'-DDT) and sigma Cyclodiene (Heptachlor, Aldrin, Heptachlor epoxide, Dieldrin, Endrin) ranged from 2.42 to 7.95, 0.14 to 5.12, 0.55 to 6.01 ng g(-1), respectively. The most dominant pollutant among the OCPs was gamma-HCH with the concentration of 3.4 (0.77 to 7.21) ng g(-1). Total PCB concentrations ranged between 0.59 and 15.93 ng g(-1). Low chlorinated biphenyls (tri- and tetra-) dominated in total PCBs. Positive correlations were observed between the EDDT, sigma Cyclodiene, sigma OCP or sigma PCB and TOC of the sediments (P < 0.05, n = 10). No obvious correlation was observed between the sigma HCH and the TOC of the sediments.

Monitoring and assessment of persistent organochlorine residues in sediments from the Daliaohe River watershed, northeast of China

Surface sediment samples from 12 sites of the three selected rivers in Daliaohe River watershed (Hunhe River, Taizihe River and Daliaohe River) were analyzed with the objective of establishing sources and hazard of the organochlorinae pesticides (OCPs) and polychlorinated biphenyl (PCBs) in surface sediments. The total concentrations of OCPs varied from 3.06 to 23.24 ng g(-1). SigmaHCH (alpha-HCH, beta-HCH, delta-HCH, gamma-HCH), SigmaDDT (p, p'-DDE, p, p'-DDD, o, p'-DDT, p, p'-DDT) and SigmaCyclodiene (Heptachlor, Aldrin, Heptachlor epoxide, Dieldrin, Endrin) ranged from 1.86 to 21.48, 0.5 to 2.81 and 0.56 to 1.53 ng g(-1), respectively. Results of OCPs also illustrate that the most dominant pollutants among the OCPs was SigmaHCH, and gamma-HCH was the most dominant isomer in HCH, which was evidence of recent input of lindane. It possibly came from the runoff of polluted soils and long-scale transportation. Total PCB concentrations ranged between 1.88 and 16.88 ng g(-1). The peak concentrations of PCBs were found in sediments from station T5 and D3, which are in the vicinity of industrial areas and ferry, respectively. These data show a moderate level of OCPs and PCBs contaminations compared to that in other countries.

Occurrence of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls pollution in sediments from the Haihe River and Dagu Drainage River in Tianjin City, China

The pollution status of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in the sediments of Haihe River, which is the most polluted among the seven largest basins in China, Dagu Drainage River flowing through a chemical industry zone, and two other rivers flowing into Bohai Sea in Tianjin City, China were investigated. The concentrations of PCDD/Fs and PCBs in the sediments from the mainstream of Haihe River were 1.3-26pgI-TEQg(-1) dry weight (dw) and 0.07-0.54pgTEQg(-1)dw, respectively. Heavy PCDD/Fs and PCBs pollution, with 1264pgI-TEQg(-1)dw and 21pgTEQg(-1)dw, was found in sediment from Dagu Drainage River. The congener profiles of PCDD/Fs indicated that the principal contamination source was the production of pentachlorophenol (PCP) or PCP-Na in this area. The correlation between PCDD/Fs or PCBs and total organic matter (TOM) showed that PCDD/Fs or PCBs were independent on TOM.

Polychlorinated biphenyls and organochlorine pesticides in Baltic Sea sediments and bivalves

The levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (p,p'-DDT, p,p'-DDD, p,p'-DDE, alpha-HCH, gamma-HCH, HCB) were determined in Baltic Sea sediments and bivalves. Concentrations of PCBs in surface sediment (0-5 cm), calculated as the sum of seven CBs (CB28, 52, 101, 118, 138, 153, 180) in one centimeter slices, ranged from 0.04 to 6.2 microg kg(-1) on a dry weight basis (dw), and from 5.8 to 78 microg kg(-1) C on a total carbon basis; corresponding sums of DDTs (p,p'-DDT, p,p'-DDD and p,p'-DDE) ranged from 0.13 to 5.0 microg kg(-1) dw and 3.6 to 160 microg kg(-1) C. The concentration ranges of alpha-HCH, gamma-HCH and HCB were found to be 0.007-0.4, 0.003-0.2 and 0.002-0.4 microg kg(-1) dw and 0.32-5.6, 0.05-3.4 and 0.19-7.5 microgkg(-1) C, respectively. In bivalves, the sum of CBs varied in the range 72-110 microg kg(-1) on a lipid weight (lw) basis (1.3-4.3 microg kg(-1) on a wet weight basis, ww), while the sum of DDTs varied from 66 to 140 microg kg(-1) (lw) (1.4-4.4 microg kg(-1), ww). The concentration ranges of alpha-HCH, gamma-HCH and HCB in bivalves were found to be 4.2-10, 4.7-11 and 3.0-6.8 mirog kg(-1) (lw) in bivalves, respectively. In surface sediments, CB 138 and CB153 were predominant among the CBs and p,p'-DDD among the DDTs, whereas in bivalves CB153, CB138 and p,p'-DDE predominated. Based on ecotoxicological assessment criteria, cause for concern regarding CBs in sediments was indicated for the Gulf of Finland and the Northern Baltic Proper. The concentration levels of DDTs and CBs in bivalves indicated the possibility of biological effects, and that even long-term biological effects are likely in the case of DDTs in the Hanö Bight (the Bornholm basin).

Distribution patterns of nitrobenzenes and polychlorinated biphenyls in water, suspended particulate matter and sediment from mid- and down-stream of the Yellow River (China)

Samples of water, suspended particulate matter (SPM) and sediment were collected from mid- and down-stream of the Yellow River. The distribution and concentration of 10 nitroaromatic compounds and polychlorinated biphenyls (PCBs) were extensively studied. The total concentration of 10 nitrobenzenes (SigmaNBs) varied from 0.269 to 9.052 microg l(-1) in water, from 2.916 to 164.4 microg kg(-1) dry weight in SPM, and from 0.954 to 14.72 microg kg(-1) dry weight in sediment. PCBs associated with the sediments, measured as the summed responses of Aroclor 1242, 1248, 1254, 1260 (in comparison to those of a standard 1:1:1:1 mixture), were found to be in the range of non-detectable to 5.98 microg kg(-1). In the samples collected, various PCB congeners showed similar distribution characteristics with congeners containing 3-5 chlorine atoms accounting for more than 96.4% of total PCB. In most of the samples, PCB concentrations occurred in the order: TetraCB > TriCB > PentaCB. Levels of SigmaNBs in the Yellow River were relatively low in comparison with values reported from other river and marine systems, and PCB levels were comparatively low. Relative to the PCBs, SigmaNBs showed significantly more difference among the various stations, presumably due to the influence of different pollution sources. No obvious correlation was observed between the pollutant concentrations and either the TOC or the grain size of the sediments.

Nationwide monitoring of polychlorinated biphenyls and organochlorine pesticides in sediments from coastal environment of Korea

To assess the organochlorine contamination in the Korean marine environment, a nationwide monitoring study was conducted. A total of 138 surface sediments, covering the whole Korean coast, were collected and analyzed. Organochlorine compounds (OCs) were widely distributed in the Korean coastal environment, with PCB and DDT contamination being particularly prevalent. The overall concentrations of PCBs, DDTs, HCHs, CHLs, and HCB in surface sediments were in the range of 0.088-199ngg(-1) (median value: 1.56ngg(-1)), 0.006-135ngg(-1) (0.68ngg(-1)), not detected (ND)-5.46ngg(-1) (0.32ngg(-1)), ND-3.26ngg(-1) (0.14ngg(-1)), and ND-2.59ngg(-1) (0.05ngg(-1)), respectively. The southeastern coast was found to be highly contaminated. Overall contamination status of Korean coastal sediments with regard to OCs is lower than that of USA. With the exception of highly industrialized sites, Korean coastal areas in general showed similar OC concentrations to those of other Asian countries. There was a significant correlation between distributions of most organochlorine contaminants with each other. OC contamination is closely related to shipping and industrial activities. Of the 7 sites categorized as highly polluted, 4 are in a harbor zone. Adverse effects to benthic communities are expected at the levels of OC contamination observed from harbor and industrial areas.

Seasonal variation of surface sediments composition in Mondego River estuary

Concentrations of major (Al, Si, Ca, Mg, Fe), minor (Mn), and trace elements (Zn, Pb, Cr, Cu, Ag, Cd, Hg) and organochlorine compounds (PCB congeners, pp'DDT, and metabolites) were determined in 24 samples of surface sediments (0-5 cm) collected along the Mondego River estuary in two periods: February and August 2003. All sediment samples showed low levels of contamination reflecting the weak industrialization of the region. Higher incorporation of elements (Mg, Fe, Zn, Cr, Cu, Cd, Hg) and DDT was registered in muds deposited in the inner part of the south channel. Sediments of the rest of the estuary are coarser (mean Si/Al ratio around 11) and showed much lower Me/Al ratios. Concentrations of Mn, Pb, Ag, and PCB showed no geographical distribution tendency. However, Pb, Cu, Ag, Zn, Cd ratios to Al and PCB concentrations were higher in coarser sediments collected in February than in August. In addition, the lower chlorinated CBs (tri + tetra-CB) showed a higher proportion in sediments collected in February, due to its higher mobility and low contamination in the area. The results obtained in this river-dominated estuarine system, with weak local contamination sources, indicate that chemical composition of surface sediments reflects the diffuse source of contaminants associated with the rainy season.

Determination of polychlorinated dibenzo-p-dioxins and dibenzofurans and comparison of extraction methods for edible freshwater fish and frogs in South Korea by using a high-resolution GC/MS

Three different extraction methods were evaluated: Soxhlet extraction, accelerated solvent extractor extraction and alkali digestion with high-resolution gas chromatography/high-resolution mass spectrometry, for the analysis of edible freshwater fish and frogs. The recovery efficiencies for the different extraction methods were also compared. Using these extraction methods, the concentrations and spatial distributions of these compounds in freshwater fish and frogs (n = 99), collected from 31 locations on four major river systems (Han, Nakdong, Kum and Youngsan) and two wetlands in South Korea, were examined. The concentrations of total polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in all the freshwater fish and frog samples were analysed. The toxic equivalency (TEQ) concentration of PCDD/Fs in fish ranged from 0 (n.d.) to 1.309 pg I-TEQ g(-1) wet weight. Detailed concentrations for different types of fish were as follows (pg I-TEQ g(-1) wet weight): 0 (n.d.)-1.309 for crucian (mean 0.331, n = 28), 0.004-0.743 for carp (0.244, n = 10), 0.004-0.592 for dace (0.198, n = 8), 0.187-0.400 for cornet fish (0.287, n = 3), 0.164-0.410 for Korean piscivorous chub (0.303, n = 6), 0.105-0.516 for bass (0.310, n = 2), 0.451-0.812 for mullet (0.631, n = 2), 0.082 for long-nosed barbell, 0.100 for common Korean bitterling and 0.995 for dark chub. The total TEQ concentration ranged from 0 (n.d.) to 1.258 pg I-TEQ g(-1) wet weight for the two kinds of frogs (n = 36) investigated: 0 (n.d.)-1.258 pg I-TEQ g(-1) (mean 0.346, n = 29) for the bullfrog and from 0 (n.d.)-0.474 pg I-TEQ g(-1) (0.185, n = 7) for the mountain frog.

Horizontal and vertical distribution of PCBs and chlorinated pesticides in sediments from Masan Bay, Korea

Horizontal and vertical distributions of organochlorine compounds (OCs) were determined in sediments from Masan Bay. The concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), HCB, hexachlorocyclohexanes (HCHs) and chlordane related compounds (CHLs) in sediments were in the range of 1.24-41.4, 0.28-89.2, 0.02-0.59, nd-1.03, and nd-2.56 ng/g, respectively. The spatial distribution of OCs showed a negative gradient from the inner of the bay to outer part of the bay, indicating that the source of OCs was probably located inside the bay. Compositional pattern of PCB congeners showed a relatively high concentration of high-chlorinated congeners in the inner part of the bay and a relatively low concentration of low-chlorinated congeners in the outer part. In sediment core from Masan Bay maximum concentrations of PCBs and DDTs are observed in the subsurface samples and correspond to an age of early 1980s and late 1960s. The concentration profiles of PCBs and DDTs in sediments of Masan Bay appear to correspond to use of PCBs and DDTs in Korea.