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ABSTRACT: Pearl River Estuary (PRE) is the largest estuary in Southern China and there has been an increasing concern of metal pollution due to regional industrialization. In this study, we investigated the spatial variation of metal pollution (Ag, As, Cd, Cu, Pb, and Zn) as well as their subcellular handling in the oyster Crassostrea hongkongensis. Hot spots of metal contamination in the oysters were found in different sites, suggesting that there were different sources of metals in the estuary associated with industrial activity. Metals differed in their subcellular bindings in the oysters from different locations. Metal distribution in the biologically detoxified fraction decreased for Cu but increased for Zn with increasing contamination in the oysters. For Zn, there was a significant difference in its two detoxification pools (metal-rich granules and metallothionein-like proteins) in response to Zn contamination. The high Cd concentrations in oysters may carry a high Cd hazard to the consumers.
Marine pollution bulletin 03/2013; · 2.63 Impact Factor
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ABSTRACT: Surface sediments and sediment cores collected from the Pearl River Estuary (PRE) were analyzed for total mercury (THg) concentrations and speciation using a sequential extraction method. The mobility of Hg in sediments was also assessed using a series of single extraction methods. The surface sediments from the PRE showed slightly elevated levels of Hg, with concentrations ranging from 109 to 453 ng/g. The vertical profile of THg in sediment cores indicated an accelerated input of Hg over the past decades. The organo-chelated and strong-complexed Hg species were the dominant Hg species in the sediments, while the more mobile phases of Hg made up less than 0.5% of THg. Less than 10% of the Hg in the sediments was extracted by single extraction, depending on the extractant employed. Significant relationships were found between the total organic carbon and THg, geochemical speciation, and extractability, indicating the important role of organic matter in controlling the distribution, mobility, and bioavailability of Hg in sediments.
Marine pollution bulletin 04/2012; 64(8):1699-704. · 2.63 Impact Factor
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ABSTRACT: Differences in the accumulation of mercury (Hg) in five species of marine bivalves, including scallops Chlamys nobilis, clams Ruditapes philippinarum, oysters Saccostrea cucullata, green mussels Perna viridis, and black mussels Septifer virgatus, were investigated. The bivalves displayed different patterns of Hg accumulation in terms of the body concentrations of methylmercury (MeHg) and total Hg (THg), as well as the ratio of MeHg to THg. Parameters of the biodynamics of the accumulation of Hg(II) and MeHg could reflect the species-dependent Hg concentrations in the bivalves. With the exception of black mussels, we found a significant relationship between the efflux rates of Hg(II) and the THg concentrations in the bivalves. The interspecific variations in the MeHg to THg ratio were largely controlled by the relative difference between the elimination rates of Hg(II) and MeHg. Stable isotope (δ(13)C) analysis indicated that the five bivalve species had contrasting feeding niches, which may also affect the Hg accumulation.
Environmental pollution (Barking, Essex: 1987) 07/2011; 159(10):2500-6. · 3.43 Impact Factor
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ABSTRACT: Rapid growth of the economy in China has been coupled with increasing environmental pollution. The coastal and estuarine ecosystems in China are now facing increasing metal pollution pressures because of the elevated metal discharges from various sources. Industrial and domestic sewage discharges, mining, smelting, e-wastes recycling are important sources contributing to coastal pollution in China. In this review, status of metal contamination along China's coasts is assessed by a comprehensive review of metal concentrations recorded in sediments and marine organisms over the past ten years. Studies show that metal contamination in the coastal environments is closely associated with accelerated economic growth in the past decades. High metal contents can be detected in the sediments collected across the coasts in China. Alarmingly high metal concentrations are observed in the sediments, water and organisms collected from the heavily industrialized areas. Metal levels observed in marine bivalves also consistently reflect the elevated metal contamination. Elevated levels of metal contamination along China's coastal environment can increase the risk of metal exposure to humans by seafood consumption, raising the alarm for more stringent control of discharge of metals into environment.
Science of The Total Environment 04/2011; 421-422:3-16. · 3.29 Impact Factor
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ABSTRACT: Sediments and sponges were collected from various locations along the eastern coast of the Red Sea, the Kingdom of Saudi Arabia. Total concentrations of Cd, Zn, Ag, Cu, Pb, As and Hg in the sediments were measured. Metal contamination was not significant in most of the studied sites and only one site was moderately polluted by Zn, Cu, and Pb. Sponges accumulated specific metals readily even though the metal exposure was low in the ambient environment. Contrasting interspecies differences in metal accumulation patterns were observed among the nine collected species of sponges. Significant positive correlations were found between the metal concentrations in the two species of sponges collected from the same sites. The strong ability to accumulate specific metals and the diversity of sponges that live in the Red Sea coastal areas make them a promising biomonitor of metal contamination in the areas.
Marine pollution bulletin 03/2011; 62(5):1140-6. · 2.63 Impact Factor
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ABSTRACT: Butenolide [5-octylfuran-2(5H)-one] is a recently discovered and very promising anti-marine-fouling compound. In this study, the acute toxicity of butenolide was assessed in several non-target organisms, including micro algae, crustaceans, and fish. Results were compared with previously reported results on the effective concentrations used on fouling (target) organisms. According to OECD's guideline, the predicted no effect concentration (PNEC) was 0.168 µg l(-1), which was among one of the highest in representative new biocides. Mechanistically, the phenotype of butenolide-treated Danio rerio (zebrafish) embryos was similar to the phenotype of the pro-caspase-3 over-expression mutant with pericardial edema, small eyes, small brains, and increased numbers of apoptotic cells in the bodies of zebrafish embryos. Butenolide also induced apoptosis in HeLa cells, with the activation of c-Jun N-terminal kinases (JNK), Bcl-2 family proteins, and caspases and proteasomes/lysosomes involved in this process. This is the first detailed toxicity and toxicology study on this antifouling compound.
PLoS ONE 01/2011; 6(8):e23803. · 4.09 Impact Factor
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ABSTRACT: Copper is an essential metal for organisms but can be toxic when high intake occurs. The interspecific and intraspecific differences in concentrations of Cu in the tissues of different bivalve species have been recognized but the underlying mechanisms leading to these differences remain speculative. In this study, the biokinetics of Cu, using 67Cu as a radioactive tracer, was investigated in five species of marine bivalves, including scallops Chlamys nobilis, clams Ruditapes philippinarum, green mussels Perna viridis, black mussels Septifer virgatus, and oysters Saccostrea cucullata. All species have contrasting Cu concentrations in their bodies. Our results demonstrated the clear importance of biokinetics in controlling Cu concentrations in the bodies of bivalves. Assimilation efficiency (AE), feeding activity (filtration rate), and efflux rate all contributed to the observed interspecies differences. The AE and efflux rate were positively correlated with the respective Cu body burden, indicating their important roles in Cu concentrations in the body. The efflux rate also explained the intraspecies difference in Cu bioaccumulation. The subcellular distribution of Cu varied among different species of bivalves. There was a positive relationship between the newly accumulated Cu in the metallothionein-like protein (MTLP) fraction and the efflux rate, suggesting that MTLP may be responsible for Cu elimination and may control Cu regulation in bivalves. Calculations showed that the Cu partitioning coefficient and ingestion are important in determining the relative contribution of waterborne and dietborne exposure pathways to overall Cu accumulation. However, the dietary pathway was the most important source of Cu in bivalves under most circumstances.
Environmental Science and Technology 04/2009; 43(6):2137-43. · 5.23 Impact Factor
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ABSTRACT: Subcellular metal distribution has received increasing attention in aquatic toxicology studies, but the relationship between metal distribution and metal biokinetics remains largely unexplored. A series of short-term experiments on different concentrations of dissolved and dietary metals and on metal elimination were conducted to investigate the dynamics of subcellular distribution of Cd and Zn in the scallop Chlamys nobilis, a bivalve species that is known to accumulate very high concentrations of Cd and Zn in its tissues. Our results showed that, in general, both Cd and Zn were sequestered in insoluble forms (organelles, metal-rich granules, and cellular debris). The main binding pool for the newly acquired metals was organelles for Cd and cellular debris for Zn. Metallothionein-like protein (MTLP) was the most important storage pool for Cd in the scallops. Storage in the non-toxic form both in organelles and MTLP instead of through exocytosis was the major detoxification strategy to control Cd and accounted for the low efflux rate of Cd from scallops. In contrast to Cd, the main binding pool for Zn was cellular debris. Significant changes were found in the scallops when they were challenged with different concentrations of metals in the aqueous and food phases. Such changes provide important information on how scallops handle metals when there is increasing metal uptake. The redistribution of Zn among each subcellular compartment was much faster than the redistribution of Cd, suggesting an effective regulation mechanism for Zn in scallops. Thus, knowing subcellular metal distribution helps in studying the toxicity of both waterborne and dietborne metals.
Aquatic toxicology (Amsterdam, Netherlands) 01/2009; 90(4):253-60. · 3.12 Impact Factor
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ABSTRACT: A transplantation experiment, using the scallop Chlamys nobilis as the model organism, was carried out to investigate variations in their bioaccumulation of Cd and Zn in different environmental conditions. The diffusive gradients in the thin films technique was employed to monitor in situ dissolved labile metal concentrations. The impact of food quality on assimilation efficiency and ingestion rate also was investigated in the laboratory. The results were combined in a biokinetic model explaining the metal concentrations accumulated in the scallops. The results confirm that scallops accumulate metals differently in different marine environments with comparable ambient metal concentrations. Food quality not only influences their assimilation of metals but also their clearance rates. The ingestion rate together with the growth rate was shown to have an effect on the bioaccumulation of metals. Bioaccumulation is dependent on both the ingestion rate (when food is the dominant metal uptake pathway) and the proportion of metal taken up from the water. Environmental conditions such as food availability and hydrology must be simultaneously considered in any attempt to study metal bioaccumulation in marine bivalves.
Environmental Science and Technology 09/2008; 42(16):6285-90. · 5.23 Impact Factor
