Relationship between carbonaceous materials and polychlorinated biphenyls (PCBs) in the sediments of the Danshui River and adjacent coastal areas, Taiwan

Persistent organic pollutants, POPs (e.g., polychlorinated biphenyls) can seriously and deleteriously affect environmental quality and human health. These organic pollutants are exhibiting high affinities to solid phases and thus, quickly end up in sediments. To better understand the role of carbonaceous materials in the transport and distributions of POPs in terrestrial and near-shore environments, concentrations of PCBs and carbonaceous materials (including total organic carbon, black carbon and total carbohydrates), were determined in surface sediments of the Danshui River and nearby coastal areas, Taiwan. Total concentrations of PCBs in the sediments ranged from non-detectable to 83.9 ngg(-1), dry weight, with the maximum value detected near the discharge point of the marine outfall from the Pali Sewage Treatment Plant. These results suggest that the sewage treatment plant has discharged PCBs in the past and the concentrations are still high due to their persistence; alternatively, PCBs are still being discharged in the estuarine and near-shore environment of the Danshui River. Organic carbon and black carbon concentrations correlated well with those of total PCBs in the sediments, suggesting that both organic carbon and black carbon significantly affect the distribution of trace organic pollutants through either post-depositional adsorption, or by co-transport of similar source materials. The field results demonstrate that black carbon and plays an important role in the general distribution of PCBs, while concentrations of some specific PCBs are affected by both black carbon and organic carbon concentrations.     

Black carbon: the reverse of its dark side

The emission of black carbon is known to cause major environmental problems. Black carbon particles contribute to global warming, carry carcinogenic compounds and cause serious health risks. Here, we show another side of the coin. We review evidence that black carbon may strongly reduce the risk posed by organic contaminants in sediments and soils. Extremely efficient sorption to black carbon pulls highly toxic polycyclic aromatic hydrocarbons, polychlorinated biphenyls, dioxins, polybrominated diphenylethers and pesticides into sediments and soils. This increased sorption is general, but strongest for planar (most toxic) compounds at environmentally relevant, low aqueous concentrations. Black carbon generally comprises about 9% of total organic carbon in aquatic sediments (median value of 300 sediments), and then may reduce uptake in organisms by up to two orders of magnitude. This implies that current environmental risk assessment systems for these contaminants may be unnecessarily safe.     

Organochlorine contaminants in the estuarine and coastal marine environments of the Fiji Islands

No information has been published on the presence of organochlorine pesticides and polychlorinated biphenyls in the Fiji Islands. This paper reports the first data on the concentration of a range of organochlorine compounds in sediments and shellfish in the estuarine and coastal marine environment around Fiji. Twenty-three sediment and two shellfish samples were analysed for 22 pesticides and related residues, and PCBs. While a significant number of organochlorines (20 pesticide related species and PCBs) was detected, the concentrations were generally very low (< 10 ng g), indicative of a relatively 'less contaminated' marine environment. Relatively high concentrations were observed only near the two major ports (Suva and Lautoka), with Suva harbour samples having the largest number of detectable species and the largest total concentrations of organochlorines (up to 91 ng g). No PCBs were detected in areas away from major industrial centres. The variations in the concentrations found, and the possible sources and movement of the organochlorine contaminants are discussed.     

Distribution of polycyclic aromatic hydrocarbons in water and surface sediments from Daya Bay,China

Marine culture is thriving in China and represents a major component of the regional economy in coastal zones, yet the environmental quality of many of those areas has never been studied. This paper attempts to investigate the quality status of Daya Bay, a key aquaculture area in China. The levels of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in water and sediment samples of the bay. The total concentrations of 16 PAHs varied from 4228 to 29325 ng l(-1) in water, and from 115 to 1134 ng g(-1) dry weight in sediments. In comparison to many other marine systems studied, the PAH levels in Daya Bay waters were relatively high, and at six sites they were sufficiently high (> 10 microg l (-1)) to cause acute toxicity. The PAH composition pattern in sediments suggest dominance by medium to high molecular weight compounds, and the ratio of certain related PAHs indicate important pyrolytic and petrogenic sources. Further analysis showed that the distribution coefficient (KD) increased with the particular organic carbon content of sediments, consistent with the PAH partition theory. The organic carbon normalised distribution coefficient (K(oc)) also increased with the compounds' octanol/water partition coefficient (K(ow)), confirming the potential applicability of the linear free energy relationships in the modelling and prediction of PAH behaviour in marine environments.     

Bages-Sigean and Canet-St Nazaire lagoons (France): physico-chemical characteristics and contaminant concentrations (Cu,Cd, PCBs and PBDEs) as environmental quality of water and sediment

Environmental characteristics in water and sediments of two contrasted coastal Mediterranean lagoons, Bages-Sigean and Canet-St Nazaire, were measured over a three season survey. The urban pollution (treatment plant discharges) is very important in Canet-St Nazaire lagoon reflecting untreated sewages, while in Bages-Sigean, the northern part appears more impacted due to larger anthropogenic inputs. Dissolved Cd concentrations are on the whole similar in both lagoons, whereas Cu concentrations are by far higher in lagoon Canet-St Nazaire. Cu concentrations appear to be highly dependent on dissolved organic carbon whereas salinity seems to control Cd variations. Concerning the sediments, the confined northern part of lagoon Bages-Sigean shows organic carbon and total nitrogen enrichment whereas lipid concentrations are much higher in the Canet-St Nazaire lagoon. Cu complexation seems to be strongly related to organic matter as evidenced by the two significant positive relationships, on one hand between Cu and organic carbon, and on the other hand, between Cu and lipids. On the contrary, Cd concentrations appear to be mainly controlled by carbonates. PCBs and PBDEs were detected only in sediments and show relatively low concentrations compared to similar lagoon environments. Regarding the sediment quality guidelines, Cd, Cu and PCBs in both lagoons did not exceed any Probable Effect Concentration (PEC).     

Investigations into the PCDD contamination of topsoil,river sediments and kaolinite clay in Queensland,Australia

Recent findings of elevated PCDDs from an unknown source in the coastal marine environment of Queensland, Australia has instigated further investigations into the distribution of, and environments associated with the PCDD contamination. This study presents data for OCDD concentrations in the coastal, mountainous and inland environment of Queensland. Additionally, full 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/F) profiles from different land-use types and environments in the coastal region were analysed. Distinct east–west gradients were detected in topsoil collected from various bushland regions with elevated OCDD concentrations confined to the coastal region. However, PCDD/F results from topsoil and river sediments collected in the Queensland coastal region suggest that elevated OCDD concentrations cannot be attributed to any of the environments, land-use or industry types investigated. PCDD/F congener profiles from select samples were remarkably similar to those previously described in marine sediments collected along the entire Queensland coastline. In addition, kaolinite clay samples from Queensland exhibited elevated OCDD concentrations, and PCDD/F profiles in these samples were similar to those detected in kaolinite clays elsewhere. Natural formation processes have been hypothesised as the source of elevated PCDDs in Queensland and other locations, where similar PCDD/F profiles and the general lack of anthropogenic sources are evident. This study presents additional data supporting this hypothesis and provides further information that may assist in the identification of the processes involved in the natural formation of PCDDs.     

Polychlorinated organic compounds in Yangtse River sediments

Polychlorinated organic compounds (PCOCs) were analyzed in Yangtse River sediments. The results show that the concentrations of PCOCs in Yangtse River sediments followed the order of DDTs > HCB > HCHs > PCBs. High PCOCs concentrations were detected in sediments from station Y02a and Y02b, which are located in the main input of the Yangtse River (Nanjing section). Results also show that the PCOCs values were highly correlated with organic carbon content and heavy metal contamination.     

Land-based sources of marine pollution: organochlorine pesticides in stream systems

BACKGROUND: Organochlorine pesticides (OCPs) have been dispersed ubiquitously in the environment. Bottom sediments act as sinks for these compounds and their concentrations often reflect the degree of anthropogenic pollution. This study was designed to evaluate the occurrence and distribution of OCPs in superficial streambed sediments and their relation to land use in two creeks that contribute to the coastal pollution of the southeastern region of Argentina. METHODS: Sampling sites were selected by a combination of land use and stream type. Las Brusquitas creek, which passes through vast agricultural areas, and La Tapera creek which originates in a natural wetland and passes through horticultural farming and urban areas. OCPs quantification was carried out by GC-ECD. RESULTS AND DISCUSSION: Results showed similar total OCP concentrations in sediments from both creeks in the range of 6-25 ng/g dry wt. However, when OCPs were expressed in ng/g total organic carbon (TOC), La Tapera creek presented 4-fold higher total levels as a consequence of a higher OCP input during the recent past in that watershed. La Tapera outfall showed 4-fold higher levels than that seen in Las Brusquitas, although both values were below the sediment quality criteria demanded to protect wildlife. Sigmaendosulfans, sigmaDDTs and sigmachlordanes were the main OCP group in all samples, with Endosulfan sulfate being the most frequent and abundant compound. The predominance of metabolites with respect to parent compounds suggests a contamination mainly by runoff from aged and weathered agricultural soils. CONCLUSIONS: Despite OCPs being banned, they still exist in creek sediments from the studied region, representing continuous contributions of land-based source contaminants to the marine environment. OUTLOOK: Future research on OCP levels in suspended sediments is recommended in order to determine the total OCP concentrations in the selected stream systems.     

Biological and chemical transformation of atrazine in coastal aquatic sediments

The degradation and distribution potential of atrazine, a persistent triazine herbicide, into three chemical fractions were measured in coastal aquatic sediments in the laboratory over time. Sediments with varying organic carbon contents were extracted with an organic solvent followed by an alkali hydrolysis reaction, and atrazine, deethylatrazine (DEA) and deisopropylatrazine (DIA) were quantified in the aqueous, solvent, and basic fractions using gas chromatography-mass spectrometry. The total amount of atrazine and its metabolites recovered after 95 days varied by site and ranged from 5% to 30% in which 95% was atrazine found primarily in the solvent fraction. Sediment organic carbon was positively correlated with the distribution of atrazine into the basic fraction and the decline in the total amount recovered. No DIA was detected in laboratory spiked sediments and transformation to DEA was limited in all sediments and made up less than 1% of the mass balance. The production and persistence of DEA were inversely correlated to organic carbon; sediments with less carbon and limited binding sites had increased formation and persistence of DEA. A secondary metabolite, methylated atrazine (M-ATR) not previously documented to be derived from atrazine, was chemically produced, detected in all sediments and time points, and concentrations were an order of magnitude higher than DEA. Based on results from spiked estuarine sediments, atrazine and M-ATR may have the potential to persist in the environment while DEA and DIA may not be an ecological threat due to their limited formation.     

Distribution of organochlorine pesticides in sediments from Kyeonggi Bay and nearby areas, Korea

The residues of oragnochlorine pesticides (OCPs) in 62 sediments from Kyeonggi Bay and nearby areas in the west coast of Korea were determined. The concentrations of chlordanes (CHLs) and DDTs showed a distinctive gradient of contamination between inner and outer sites of Incheon North Harbor (INH), whereas hexachlorocyclohexanes (HCHs) were uniformly distributed at most sites studied. The distribution of CHLs and DDTs was strongly correlated with total organic carbon contents in sediments while HCH residue levels were independent. Relationship between contaminant's concentration and environmental factors was analyzed by principal component analysis. Distribution patterns of T-CHLs, T-DDTs, and TOC were similar while those of T-HCHs, mud content, and grain size were similar. The notable contamination by CHLs and DDTs was found in INH where these levels were one or two orders of magnitude higher than other sites. The dominant OCPs in sediments were beta-HCH among HCH compounds, trans-chlordane among CHL compounds, and p,p'-DDD among DDT compounds. The higher concentrations and compositional pattern of OCPs in INH sediments indicate that INH is in the vicinity of the source.     

Distribution characteristics and source analysis of dioxins in sediments and mussels from Qingdao coastal sea

Seven of surface sediments, one sediment core and two mussel samples were collected from the Qingdao coastal sea of the western Yellow Sea and analyzed to determine the horizontal distribution, deposition flux, and toxicity equivalency (TEQs) of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The total PCDD/Fs concentrations in the surface sediments ranged between 10.7 and 428 ng kg(-1) dry wt. The horizontal distribution of PCDD/F congeners in the sediments was characterized by elevated concentrations at the locations in the east of Jiaozhou Bay with the highest concentration occurring near the Haibo River mouth. Physical parameters (total organic carbon contents and sediment types) and the current circulation systems in Jiaozhou Bay can be important factors controlling the horizontal distribution pattern of PCDD/Fs in the bay. The influence of the Haibo River as a source of pollution was evidenced by PCDD/F homologue profiles, indicating a contribution from sewage sludge in addition to other possible sources. Records from the sediment core revealed that the total PCDD/Fs in the Qingdao coastal sea were nearly constant since 1951 till 1980s and increased remarkably after 1980s. The total 2,3,7,8-substituted PCDD/Fs and total TEQs of PCDD/Fs on the lipid basis in the mussel sample inside the bay were significantly higher than in the adjacent sediment. The homologue profiles of PCDD/Fs in the mussels were quite different from those of the sediments, characterized by high TCDF (50% of the total PCDD/Fs).     

Distribution of PCNs, PCBs, and other POPs together with soot and other organic matter in the marine environment of the Grenlandsfjords, Norway

The apparently dissolved concentration of polychlorinated naphthalenes (PCNs) and three planar polychlorinated biphenyls (pPCBs) were sampled and analysed in the water column of a marine fjord system. We also measured how much of these persistent organic pollutants (POPs) were associated with suspended particles. The field observations showed that an unexpectedly high portion of the pollutants were particle-associated. The factor of deviation from model predictions had positive linear regression on the soot carbon:particulate organic carbon ratio of the particles, and on estimates of the soot-water distribution coefficient for the PCNs. The spatial distribution of surface sediment concentrations of PCNs and polycyclic aromatic hydrocarbons (PAH) were found to consistently follow the sediment content of soot (f(SC)) to a larger extent than the bulk organic matter (f(OC)). There were no systematic differences in the strength of correlation of sediments concentrations of other POPs, i.e. octachlorostyrene and organochlorine pesticides with sediment concentration to f(SC) and f(OC). Mechanisms possible of generating these types of observations, e.g. adsorption to soot carbon in the marine particle, are discussed.     

Effect of condensed organic matter on solvent extraction and aqueous leaching of polycyclic aromatic hydrocarbons in soils and sediments

The contents of nonhydrolyzable organic matter (NHC) and black carbon (BC) were measured in soils and sediments from the Pearl River Delta, South China. Polycyclic aromatic hydrocarbons (PAHs) were extracted respectively by Soxhlet and an accelerated solvent extraction device (ASE) using different solvents. In addition, sequential aqueous leaching at different temperatures was carried out. The PAH content extracted with the sequential three solvent ASE is two times higher than that using the Soxhlet extraction method. The relationship of the PAH content with the NHC content is very significant. The PAH concentrations measured at various temperature steps fit well to the Van't Hoff equation and the enthalpy was estimated. The investigation indicates that condensed organic matter such as kerogen carbon, aged organic matter, and BC is relevant for the extraction and distribution of native PAHs in the investigated field soils and sediments.     

Relation between PAH and black carbon contents in size fractions of Norwegian harbor sediments

Distributions of total organic carbon (TOC), black carbon (BC), and polycyclic aromatic hydrocarbons (PAH) were investigated in different particle size fractions for four Norwegian harbor sediments. The total PAH (16-EPA) concentrations ranged from 2 to 113 mg/kg dry weight with the greatest fraction of PAH mass in the sand fraction for three of the four sediments. TOC contents ranged from 0.84% to 14.2% and BC contents from 0.085% to 1.7%. This corresponds to organic carbon (OC = TOC - BC) contents in the range of 0.81-14% and BC:TOC ratios of 1.3-18.1%. PAH isomer ratios suggested that the PAH in all four sediments were of pyrogenic origin. Furthermore, stronger correlations between PAH versus BC (r2 = 0.85) than versus OC (r2 = 0.15) were found. For all size fractions and bulk sediments, the PAH-to-BC ratios for the total PAHs were on average 6+/-3 mg PAH/g BC. These results suggest that PAH distributions were dominated by the presence of BC, rather than OC. As sorption to BC is much stronger than sorption to OC, this may result in significantly lower dissolved concentrations of PAH than expected on the basis of organic carbon partitioning alone.     

Distribution and fate of organochlorine pesticide residues in sediments from the selected rivers in Taiwan

The contamination of organochlorine pesticides (OCPs) in sediments from selected rivers in Taiwan was investigated to evaluate the pollution potentials and hazard in river sediments. Da-han River and Erh-jen River were selected as the target rivers due to their serious pollution. A total of 40 surface sediment samples were collected at five sampling stations along the rivers. Results showed that the concentrations of various pesticides in sediments were in the range of 0.57-14.1 ng/g for sigmaHCH, 0.05-0.15 ng/g for aldrin, 0.12-5.8 ng/g for dieldrin, 0.22-0.64 for endrin, 0.24-6.37 ng/g for endosulfan and 0.21-8.81 ng/g for EDDT (p,p'-DDD, p,p'-DDE, p,p'-DDT). Among the OCPs, sigmaHCH, endosulfan and sigmaDDT were the most dominant compounds in the river sediments. Endosulfan sulfate was the most frequent detected compound in the sediments from the selected rivers. Also, sigmaDDT, dieldrin and beta-HCH were in abundance. Different contamination patterns between the selected river sediments were also observed. Da-han River was mainly contaminated with endosulfan sulfate and sigmaDDT. Whereas the main pesticides in Erh-jen River were beta-HCH and sigmaDDT. Among the cyclodiene compounds, dieldrin was in abundance in most of the sediments. Moreover, the frequencies of detection of the metabolites were higher than those of parent compounds, depicting that the sediments have contaminated for a long time. The results obtained in this study showed that there still exist a variety of OCP residues in the river sediments in Taiwan.     

Distribution of alkylphenols in the Pearl River Delta and adjacent northern South China Sea, China

The occurrence of alkylphenols (APs) was investigated in surface water and sediments from the Pearl River Delta and adjacent northern South China Sea. Most of the water samples contained detectable amounts of APs, ranging up to 0.628 microg l(-1) for nonylphenol (NP) and 0.068 microg l(-1) for octylphenol (OP). APs were found in all of the sediment samples with concentrations ranging from 59 to 7808 microg kg(-1) for NP and from 1 to 93 microg kg(-1) for OP. The Zhujiang River showed the highest concentrations of APs in both water and sediments. Significant decrease of APs concentrations going from the Zhujiang River to the Shiziyang River was observed. The Xijiang River contained concentrations of APs slightly higher in water but relatively lower in sediments than the Lingding Bay, which might be attributed to their different hydrodynamic and sedimentary characteristics. There was a decreasing trend of APs in water from the rivers to the estuary and further to the sea on the whole. In the Lingding Bay and its outer waters, concentrations of APs in sediments increased to a maximum and then decrease seaward, which was consistent with the distribution trend of the sediment organic carbon contents. Linear regression analyses showed the concentrations of APs were markedly correlated with the sediment organic carbon contents, indicating that the sediment organic carbon is an important factor controlling the levels of APs in sediments.     

Trace metal distribution in sediments of the Pearl River Estuary and the surrounding coastal area, South China

Surface sediments and sediment cores collected at the Pearl River Estuary (PRE) and its surrounding coastal area were analysed for total metal concentrations, chemical partitioning, and Pb isotopic compositions. The distribution of Cu, Cr, Pb, and Zn demonstrated a typical diffusion pattern from the land to the direction of the sea. Two hotspots of trace metal contamination were located at the mixed zone between freshwater and marine waters. The enrichment of metals in the sediments could be attributed to the deposition of the dissolved and particulate trace metals in the water column at the estuarine area. The similar Pb isotopic signatures of the sediments at the PRE and its surrounding coastal area offered strong evidence that the PRE was a major source of trace metals to the adjacent coastal area. Slightly lower (206)Pb/(207)Pb ratios in the coastal sediments may indicate other inputs of Pb in addition to the PRE sources, including the inputs from Hong Kong and other parts of the region.     

Application of biological safety index in two Japanese watersheds using a bioassay battery

In order to integratedly evaluate the biological safety as a water quality index, an assessment method based on three toxicity tests (algae growth inhibition, daphnia immobilization and larval fish toxicity) was developed. In this study, the developed method was used to screen, evaluate and rank the biological safety of small rivers near agricultural, industrial and residential areas. Twenty-seven representative water samples were collected from the Kaname River watershed and the Hinata River watershed in Kanagawa Prefecture, Japan. The results indicated that (1) the biological safety of water from the Hinata River ranked much higher than those from the Suzu River and the Shibuta River due to less human activities, (2) the biological safety from outlets of paddy fields ranked much worse than those from point source discharges of toxic pollutants, (3) the use of pesticides significantly affected the water quality of nearby small rivers and ditches during the pesticide application season, (4) the effects of different kinds of pesticides could successfully be classified using one toxicity test component of the bioassay battery, and (5) there was no significant quantitative relationship between the toxicity and dissolved organic carbon (DOC) for the studied water samples. The toxicities of water samples in this study were in agreement with the concentrations of pesticides determined with chemical methods by other researchers, which demonstrated that the developed assessment method was reliable to screen site contaminated with organic chemicals for priority management.     

Distribution and sources of polycyclic aromatic hydrocarbons in the middle and lower reaches of the Yellow River, China

In this study, concentrations, distribution between different phases, transition along the Middle and Lower reaches of the Yellow River and possible sources of PAHs were assessed. Results demonstrated that the relative proportions of 15 PAHs in all stations of the main River were similar, with concentrations of benzo[a]pyrene all above drinking water standards in most of the stations sampled. PAHs concentrations in tributaries were higher than those in the corresponding sites in the main River. PAHs concentrations of suspended particles were mainly correlated with contents of total organic carbon. However, PAHs concentrations in sediments were mainly correlated to the volume of particles with size smaller than 0.01 mm. The distribution of PAHs in all media sampled indicated that sediments could act as a sink/source for PAHs in different sections and source analysis revealed that PAHs mainly originated from coal burning, although in some tributaries PAH inputs could come from combustion of petroleum.     

Organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in Singapore's coastal marine sediments

Persistent organic pollutants (POPs) are ubiquitous pollutants in the marine environment, particular in coastal areas affected by industry and shipping traffic. POPs are known for their recalcitrance and toxicity in the environment, and there is increasing concern over their global distribution and impact upon wildlife. Marine surface sediment samples taken within 6 km of the coastline of Singapore were analyzed to determine prevailing concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyl (PCBs) and polybrominated diphenyl ethers (PBDEs). Total PCB concentrations varied widely from 1.4 to 329.6 ng/g (average 73.9 ng/g), where high concentrations were detected at sample locations closest to industrial areas with intensive shipping traffic. Total DDT concentrations ranged from 2.2 to 11.9 ng/g (average 6.7 ng/g) and were lower than the concentration range of 3.3-46.2 ng/g measured for total HCH (average 18.1 ng/g). Ratios of DDT/(DDE+DDD) in sediments do not indicate recent inputs of DDT into Singapore's marine environment, but high concentrations of alpha-HCH and gamma-HCH show evidence for the usage of HCHs in Southeast Asia. Peak concentrations of cis- and trans-Chlordane were 10 ng/g. Among the PBDE congeners BDE 47, 99, and 100 only BDE 47 could be detected at a range of 3.4-13.8 ng/g (average 6.2 ng/g). The levels of OCPs, PCBs and PBDEs were compared to available data for other countries in Asia, and indicated relatively moderate levels of contamination. Peak concentrations of PCBs, HCH isomers, Chlordane, Heptachlor, Heptachlor epoxide and Dieldrin have the potential to induce ecotoxicological impacts based on levels specified in the sediment quality standards of the USEPA and Canadian Council of Ministers of the Environment.