| In recent years, with the rapid development of Dalian port industry around the coastal regio ns, domestic sewage and industrial wastewater discharged into the sea, resulting in the deteriorat ion of marine environment.At the same time, freshwater lakes, rivers, and reservoirs were also p olluted because of industrial and agricultural production activities. Owing to its special physica l and chemical properties and toxic effect,Heavy metals show high hazard and intractability and have become the main factors threatening China’s environmental protection and food safety.In this paper, through a questionnaire survey of the daily consumption of aquatic products f or the residents in Dalian, the aim is to determine types and quantity of aquatic products daily c onsumed by residents, and then to select typical aquatic species from fish, shrimps, crabs, shell fish, algae, echinodermata、 annelida categories.By sampling typical aquatic products, the conten t of Cu, Cd, Pb, Hg, As in the aquatic products was detected. According to the limited standar d of heavy metal contaminants in aquatic product, the food safety of samples was evaluated.Subsequently,the exposure risk of heavy metals that is due to residents’ consumption of aq uatic productswas assessed.The main results are as follows:(1) The main results of questionnaire are:the favorite marine fish were Spanish mackerel, hairtail, large yellow, Buttercup, flo under, Raja porosa; freshwater fish were carp, common carp,grass carp, silver carp; Crus taceans were Red shrimp, shrimp, crustaceans shrimp, squilla, crab, flying crab, Eriocheir sinensis; Shellfish-oysters were scallops, razor clam, squid; Algae were kelp, laver.Echino dermata were sea cucumbers, sea urchins. Annelida was sea intestinals. Weekly consumptio n of aquatic products was freshwater fish 0.19 kg, marine fish 0.229 kg, shrimp 0.184 kg crab 0.163 kg, shellfish 0.185 kg, algae 0.13 kg and echinodermata、 annelida 0.114 kg,res pectively.(2) The main characteristics of heavy metals in aquatic products are:Marine fish body Cu content than freshwater fish, 4 other heavy metals content than freshwater fishThe content of Cu in marine fish was lower than freshwater fish.the content of othe r four heavy metals in marine fish was higher than freshwater fish.The difference was a ffected by the sources and feeding habits of fish. Raja porosa as carnivorous fish is ob tained from inshore fishing and possessed the largest fish in the average detection conte nt of four different sources of Cd, Hg, Pb and three kinds of feeding in Hg.There is a significant difference between the shrimp, crab and other shellfish sample s involving the content of Cu, Cd, Pb, Hg. The content of Cu,Cd,Pb in Oratosquilla ora toria was highest, while the content of Hg in crab samples was highest.There was significant difference between the shellfish sample for the content of Cu, Cd,As.The content of Cu,Cd in oyster samples was highest.The content of As in Sinon ovacula constrzcta samples was highest.Because the laver samples are dry products,its content of five heavy metals were hi gher than fresh kelp.There is a significant difference between the other samples in Cu,Hg,the average det ection content, sea intestinal samples in Cu were the highest content, sea urchin, sample in Hg were the highest content.Analysis of single heavy metal contents in different species indicated that there was significant difference between different samples content in Cu, Hg, As, Cd. Cu, Hg, As in Crustaceans were highest, and the Cd maximum was detected in shellfish.(3)Pollution level assessment and exposure risk analysis indicated that:(a) the concentrations of Cu and Hg elements in all samples were lower than the li mits set by the standards. The concentrations of Cd、Pb、As elements in specific sample s were exceed the limits set by the standards.(b) the ratio of Hg maximum weekly intake to PTWI was greater than 1 because of Raja porosa diet. The ratio of Cd maximum weekly intake to PTWI was greater than 1 because of Oyster diet. The ratio in other cases was less than 1.(c) Non-carcinogenic risks assessment indicated that non-carcinogenic risk quotient va lues(ΣTHQ) of Shellfish samples was significantly greater than that of other six types o f aquatic product. Oyster HQ(Cd) value was maximum. The THQ values of 5 toxic ele ments followed the order of As>Cd>Pb>Cu>Hg.This study suggests that weekly consumption for Raja porosa and oysters should be controlled under 0.2 and 0.15 kg respectively in order to reduce the intake risk of Hg and Cd. |
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