PCBs in Central Vietnam coastal lagoons: Levels and trends in dynamic environments (original) (raw)
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Polychlorinated biphenyls in sediments of the Tam Giang-Cau Hai Lagoon, Central Vietnam
Chemosphere, 2007
The Tam Giang-Cau Hai Lagoon, the largest in south east Asia, suffers from a great anthropogenic pressure and appears subject to a process of progressive environmental deterioration. To establish causes, history and trends of lagoon contamination, sediment samples representing three major parts of the systems were sampled and analysed for porosity, organic carbon, total nitrogen, d 13 C, grain size, radiotracers and PCBs. PCB surficial concentrations range from 10.2 to 24.5 lg kg À1 , and maximum values are close to NOAA ERL guidelines. The downcore distribution of PCBs shows two well defined peaks in the core from Tam Giang (25.5 and 16.2 lg kg À1 ), whereas the sediment from Cau Hai is characterised by a maximum at the surface. Therefore, present trends indicate that contamination is still increasing or slightly decreasing. The prevailing congeners are 3-CB and 4-CB, hence recent PCBs appear to be mostly originated by Aroclor 1016-and 1242-like mixtures, with some samples influenced also by Aroclor 1248. Present sources seem to be similar everywhere and probably they are widespread all over the territory of the Thua Thien-Hue province.
The status and distribution of PCBs along the coast of Vietnam
Environmental geochemistry and health, 2018
Polychlorinated biphenyls (PCBs), well-known as an important scientific achievement, are now considered as one of the most persistent organic pollutants (POPs) that need to be strictly controlled and forbidden worldwide (the Stockholm convention on POPs). Vietnam is one of the countries that encounters with serious issues from PCB contamination. This study presented a comprehensive review on the status and contamination of PCBs along the coast of Vietnam. The contaminated PCBs data in the water, sediment and biological samples from 18 provinces along Vietnam coastline were collected from various sources. A comparison in PCBs contamination between Vietnam and other Asian countries was included. The status on PCBs contamination in Vietnam since participated as a party of the Stockholm convention on POPs in 2002 was also assessed. The results showed that Vietnam is facing serious PCBs contamination problems as it evidences the spread and accumulation of PCBs in the marine environment. ...
PBDEs and PCBs in sediments of the Thi Nai Lagoon (Central Vietnam) and soils from its mainland
Chemosphere, 2013
h i g h l i g h t s " Levels and patterns of PCBs, PCB 11, and PBDEs in surface sediments and soils. " Main natural and anthropogenic processes in tropical areas are changing rapidly. " Key processes are identified by salinity, porosity and grain size patterns. " PCBs, PCB 11 and PBDEs levels are similar to those found far from direct sources. " Efficacy of degradation processes are confirmed by congener patterns and statistics.
Concentrations of PCBs in coastal mangrove sediments of Hong Kong
Marine Pollution Bulletin, 2002
The concentrations of polychlorinated biphenyls (PCBs) in surface sediments of ten mangrove sites in Hong Kong were determined by Congener-specific and Arcolor methods. Spatial variations were found between mangrove sites and within the same site, indicating that the sediment samples were heterogeneous and total PCBs concentrations in mangrove sediments should be normalised to compensate for natural variability and for identifying serious anthropogenic contamination. In addition to total organic carbon, Al, Fe and Mn were possible normalisers. Based on PCB/normaliser ratio and 95% prediction limits of scatter plots between total PCB and normaliser, all mangrove sites were not seriously contaminated by human activities. The estimated total PCBs concentrations (quantified by Congener-specific method) for most sediment ranged from 0.5 to 5.8 ng g À1 (dry weight, n ¼ 92). However, very high concentrations of PCB were found in sub-samples from Yi O, Tolo Pond and Lai Chi Wo, suggesting that these samples represented the PCB contaminated ''hot spots''.
2021
Polychlorinated biphenyls (PCBs) assessment in sediments of Turag River, Dhaka, Bangladesh has been conducted for the first time. This River provides critical ecological services to agriculture, industry, and transportation. However, the Turag River is one of the most industrially polluted rivers surrounding Dhaka in Bangladesh. In this study, six PCB congeners namely PCB 10, PCB 28, PCB 52, PCB 138, PCB 153, and PCB 180, were analyzed in surface sediments by GC-ECD at 9 sampling sites. Pre-monsoon and post-monsoon season sampling were collected in this study. The total concentrations of PCBs varied from 344.49 to 0.22 ng/g dw and 10.6 to 1.68 ng/g dw in pre-monsoon and post-monsoon, respectively. The paramount contributor congener to the total PCBs was PCB 180 and was found at all sites. The ecological risk assessment indicated a high potential risk in pre-monsoon (Eri = 277.32) and low potential risk in post-monsoon (Eri = 25.69). Sediment quality guideline quotients (SQGQs) showe...
PCDD/Fs in sediments of Central Vietnam coastal lagoons: In search of TCDD
Marine Pollution Bulletin, 2010
Samples from nine Central Vietnam coastal lagoons, together with three soils and sediments collected in two freshwater reservoirs of the Thua Thien-Hué province, were analysed for polychlorinated dibenzo-pdioxins and dibenzofurans (PCDD/Fs). Total concentrations are low, from 192 to 2912 pg g À1 and depth profiles in Tam Giang-Cau Hai (TG-CH) sediment cores show only minor changes over time in PCDD/F input and composition. Octachloro dibenzo-p-dioxin (OCDD) is the prevailing congener (approximately 90%), indicating combustion as the main PCDD/F source to these coastal systems, whereas natural formation might be partly responsible for the presence at depth. 2,3,7,8-Tetrachloro dibenzo-p-dioxin (TCDD), largely sprayed together with Agent Orange over the study areas during the war (1961-1971), is absent or very low. This result supports the hypothesis of strong degradation soon after spraying. Multivariate statistical analyses account for the presence of local, short-range sources as observed in the northern part of the TG-CH lagoon.
Distributions and sources of polychlorinated biphenyls in the coastal East China Sea sediments
Science of The Total Environment, 2013
The Yangtze River estuary (YRE) and the adjacent East China Sea (ECS) inner shelf is an important sink of pollutants originated from mainland China. In this work, we studied the spatial and temporal variations and sources of polychlorinated biphenyls (PCBs) in sediments from the YRE and the ECS inner shelf. Total concentration of 23 PCBs (Σ 23 PCB) ranged between 24.3 and 343.3 pg/g (with a mean value of 126.7 pg/g), and higher values occurred in the estuarine region. The homolog profile was dominated by 3-5Cl CBs, accounting for 76.1% of Σ 23 PCB. The Cl proportion ranged from 45.1% to 58.8% (with a mean value of 49.9%); the lowest level appeared in the estuarine region, and it increased with distance from the YRE. Lower chlorinated congeners were carried mainly by the YR into the ocean, to be finally buried in sediments of the estuary region and vicinity. However, higher chlorinated ones were imported mainly via direct emission from local sources, to be finally buried in sediments farther away from the estuary. Of the PCBs in surface sediments, 40.1% came from the YR, 37.9% from the local sources and the rest 22.0% from atmospheric deposition. In a sediment core, we found that 81% of PCBs were technically produced and 19% unintentionally produced in the last century. Before the 1970s, PCB levels were influenced predominantly by the production and consumption of technical PCBs. While in recent decades, the effect of human activities on PCB levels has been increasing continuously.
Archives of Environmental Contamination and Toxicology, 2003
Various mussel and oyster samples and select top sediment samples were taken over 27 industrial and pristine coastal sites form South Korea's west, south, and east coasts. Site-specific total PCB, PCDD/F, and organochlorine TEQ levels in biota were 1-306 ng/g ww, 3-9,400 pg/g ww, and 0.3-200 pg/g ww, respectively. Temporal trends showed a general decrease in total TEQ with an increase in TEQ contribution by PCDD/Fs at most locations over the past decade. Linear regression was used to establish a relationship between each contaminant total and the respective TEQ contribution. Principal component analysis was used to model the congenerspecific PCB and PCDD/F data, and two three-component models were developed that describe the congener-specific patterns based on the variance between samples over the entire data set. Unique PCDD/F patterns were identified and discussed with respect to outliers identified in the previously established TEQ regressions and a distinct PCDD/F pattern was found that related to a single industrial source (i.e., steel mill). PCB patterns were explored in relation to those of common commercial mixtures of PCBs (i.e., Aroclors) and patterns were discussed with respect to TEQ. It was found that sites with relatively high PCB-TEQs showed an Aroclor 1254like contamination.
Environmental Earth Sciences, 2008
Concentrations of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured in 13 surficial sediment samples collected at three lacustrine locations in the surroundings of Mexico City and four coastal areas of the States of Sinaloa, Sonora, Oaxaca and Veracruz. Total PCB concentrations span the interval 3.18–621 ng g−1. The highest values (63.7–621 ng g−1) were found in Mexico City, which is a highly anthropogenically impacted area, whereas low concentrations (3.18–12.9 ng g−1) were characteristic of seven places, some of them subject to intense hydrodynamics. In these latter cases, values increase by 18–73 times if normalised against the fine fraction (silt plus clay) content in sediment. Two samples from Mexico City exceed the ERM (Effect Range Median) guidelines and are likely to cause adverse effects. Samples contain only lower chlorinated PCBs (mainly 2-, 3- and 4-CB), thus suggesting that the most used PCB commercial mixture was Aroclor 1242. The homologue composition of the sample taken close to the nuclear power plant of Laguna Verde is identical to this commercial mixture. PAHs in the same samples have relatively low concentrations (14.9–287 ng g−1), well below ERL (Effect Range Low) guidelines. The composition of PAH mixtures accounts for the influence of both petrogenic and pyrolitic sources, with these latter prevailing at some places in Mexico City.