| In recent years, heavy metal pollution has been one of the major environmental problems in Yangtze Estuary and it’s adjacent area. It’s not only threaten to the organism habitat environment, but also affect the structure and function of the ecosystem via the transfer and accumulation of the pollutants through food chains and webs. Therefore, investigation and accumulation of heavy metal in multi-phase media as well as their toxicological effects on ecosystem are important and necessary for the protection of environment, the rational development and management of living aquatic resources and the safety of sea food in this region.Shellfish culture is the pillar industry of Shengsi, Zhejiang province, but in recent years, with the increase of terrigenous pollutant into the ocean, the coastal environmental becoming serious deterioration, particularly the difficult to be degraded contaminant, like heavy metals, which caused a serious threat to the living environment of nearshore organisms. Marine shellfish is threated greater by heavy metals because of its characteristic of filter-feeding and sessile lifestyle.In this study,7 heavy metals(Cu, Zn, Cd, Cr, Pb, As and Hg)concentrations were determined in sediment and Mussels which were collected from intertidal Zone and culture fields in Gouqi Island in July,2013 and 2014. “Mairne biological quality”, the non-environmental pollution food, the limit for the deleterious matters in the aquatic product”, ”Marine sediment quality”, single factor index and potential ecological hazard index were used to evaluate the pollution standard and potential ecological hazard risk of intertidal zone and culture zone in Gouqi Island, at the same time, Stable isotope were used to calculate the trophic level of Phytoplankton, zooplankter and mussel, then investigated the Bioconcentration capacity of heavy metals along the food chain. Main contens and conclusions were shown as below:(1)The heavy metal content in the intertidal zone of sediment from high to low is: Zn>Cr> Cu>As> Pb>Cd>Hg, and the average content were:91.33,47.00,34.12, 6.62, 4.40,2.14 and 0.04mg/kg(Dry Weight),respectively; all of them are under the first class of Marine sediment quality except for Cd, which is overstep the second class. The single index of Cr, Pb, Hg and As are less than 1, belong to Low-pollution level, while Cu, Zn are middle-pollution and Cd belong to high-pollution level. The pollution status of intertidal sediment belongs to moderate pollution degree and the ecological risk of heavy metal is slight as a whole, the primary potential ecological risk factor is element(metal) Cd.(2)the average concentration of Cu, Zn, Cd, Cr, Pb, As and Hg in intertidal mussels were 3.79,18.15,3.64,0.36,0.84,0.46 and 0.01mg/kg(wet weight),respectively, Cd not only exceed the first class of Marine biological quality, but also overstep the non-environmental pollution food, the limit for the deleterious matters in the aquatic product”. The single factor index of Cd is 3.64, exceed the standard 3.64 times, and the over standard rate was above 77.8% in 7 sample sites, so, the intertidal mussels were advised not to consume. Biota-sediment accumulation factor(BSAF) indicate that, the content of heavy metals in biosome is not completely depend on the sediments;BSAF of Cd, Zn, Hg and Pb were greater than 1, therefore, mussels can be used as biological indicator of Zn, Cd, Pb and Hg in the sediment.(3)the concentrations of Cu, Zn, Cd, Cr, Pb, As and Hg in cultured mussels were 0.85,13.25,0.67,0.26,0.17,0.95 and 0.02mg/kg(wet weight), respectively. Only Cd and Pb exceed the first class of Marine biological quality, and all of the 7 kind of heavy metal contents did not overstep the non-environmental pollution food, the limit for the deleterious matters in the aquatic product”, indicated that, the cultured mussels in Gouqi Island is in good quality. The single factor index is less than one, illustrate the mussels did not polluted by heavy metal. Compared with the intertidal mussel, and other region, the heavy metal concentrations were relatively lower. The element of As in cultured mussels had the potential of over standard, we should pay more attention to it.(4)The average concentration of the heavy metals in culture fields sediment from high to low is: Zn>Cr>Cu>As>Pb>Cd>Hg, showed the same pattern as the intertidal zone. Noe of the metals exceeded the first class of Marine sediment quality, compared with the background value of North Zhejiang coastal sediments, Cd was relatively high, it was illustrated that the sediment of the culture area was polluted by Cd. But the result of single factor index and potential ecological hazard index showed that the environment of the culture region was good, meet the requirements of aquaculture.(5)Based on the result of stable isolate, the value of δ13C of phytoplankton, zooplankton and mussels is-18.58‰,-18.89‰ and-16.74‰, respectively, illustrated phytoplankton and zooplankton were the food source of mussels; the value of δ15N in phytoplankton,zooplankton and mussels was 3.64‰, 5.98‰ and 4.27‰ respectively. But this study found no appearance of heavy metal enrichment according to the food chain. As heavy metal bioaccumulation is a complex process, it’s not only depends on the trophic level, but also influenced by environment and their own, therefore, in order to aware of the characteristic of the bioaccumulation of the heavy metal along the food chain, more work should be done. |
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