Heavy Metal Enrichment Characteristics Of Dominant Species Of Fishes And Benthos In Dachen Islands

The accumulation of heavy metals in fish is affected by the pollutant concentration in water environment and closely related to the growth stage of fish.In this study,the contents of Cu,Zn,Pb,Hg,Cr,CD and As as heavy metals in seawater,surficial sediments,and muscles of typical economic fish and typical crustacean in Dachen island sea area at different growth stages were determined in September and November,2020,January and April,2021,respectively.The contents of seven heavy metals in the surface,bottom and surficial sediments of Dachen island sea area were analyzed by comprehensive pollution index method,single factor pollution index method and potential ecological risk index method.Based on the analysis of the correlation between the bioconcentration factor and the growth parameters of fish,the heavy metal accumulation ability of Sebastiscus marmoratus and Coilia nasus at different growth stages was explored.The main research results are as follows:1.Sebastiscus marmoratus was captured in this study.A total of 553Sebastiscus marmoratus captured in one study area from December 2019 to April2021 and investigated five times have the body length of 3.9～19.3 cm,10.21 cm on average,with the standard deviation of 21.11,and body weight of 2.39～142.62g,35.39 g on average,with the standard deviation of 21.08,and consist of 239adult fish and 314 young fish,with the adult fish to young fish ratio of about1:1.31.The results show that the contents of Cu,Zn,Pb,Hg,Cr,CD and As in seawater are 3.979,48.771,0.712,0.014,8.083,0.109 and 0.597μg·L^-1,respectively,which all are below the limits in Class II seawater,and in the muscle of Sebastiscus marmoratus are 1.147,1.593,0.034,0.001,0.061,0.034 and 0.011mg·kg^-1,respectively,which all don’t exceed the limits in Maximum levels of contaminants in foods and Maximum levels of poisonous and injurious substances in harmless agricultural products.The contents of Cu,Zn,Pb,Hg,Cr,and CD in Coilia nasus muscles are below the limits in Class II seawater.2.The contents of heavy metals in Sebastiscus marmoratus muscles are significantly correlated with the body length and age.The content of Hg is positively correlated with the age and body length,and the contents of Cu,Zn,Pb,Cr,CD and As are negatively correlated with age and body length.The contents of heavy metals in Sebastiscus marmoratus muscles are insignificantly correlated with the fatness in each body length and age group.In addition,the study shows that the contents of heavy metals in young Sebastiscus marmoratus in low body length and age groups are slightly higher,so adult Sebastiscus marmoratus with large body length should be caught or eaten.Considering that As and Cd cause slight pollution,the heavy metals in water and aquatic products in Dachen Island sea area should be detected more frequently.The contents of heavy metals in Coilia nasus musclea are correlated significantly with the body length and age,but insignificantly with the fatness.The contents of As,Hg and Cd are significantly positively correlated with the body length and age,while the contents of Cr,Cu and Zn are negatively correlated with body length and age.The content of Pb is insignificantly correlated with body length and growth cycle.The Coilia nasus muscles have higher enrichment ability of As,Hg,Zn and Cr and lower enrichment ability of Cd,Cu and Pb than Sebastiscus marmoratus muscles.Only the As enrichment ability is very different between Sebastiscus marmoratus and Coilia nasus.The Sebastiscus marmoratus muscles have much higher fatness,fat content and protein content than Coilia nasus muscles.3.The contents of heavy metals in crustaceans in Dachen Islands sea area were determined and the enrichment characteristics of heavy metals were discussed.The contents of As,Hg,Zn,Pb and Cr are higher in Charybdis japonica muscles than Oratosquilla oratoria muscles.The contents of CD and Cu in Oratosquilla oratoria muscles are greater than those in Charybdis japonica muscles.The BSAF of seven heavy metals in Charybdis japonica and Oratosquilla oratoria muscles are insignificantly correlated with the contents of heavy metals in surficial sediments and bottom water in Dachen Island sea area.The contents of heavy metals in Charybdis japonica and Oratosquilla oratoria muscles don’t exceed the limits,resulting in low risk of food safety hazards.4.The measured contents of heavy metals in Granulifusus kiranus in Dachen Island sea area exceed the limits in relevant national standards.For example,the content of As in Sepiella maindroni de Rochebrune,and the content of Hg in Octopus variabilis,the contents of As and Hg in Loligo beka,and the contents of As,Cu and Cr in Octopus vulgaris exceed the limits in national standards.In terms of food safety hazards,Octopus variabilis and Loligo edulis have relatively low contents of heavy metals.There are significant differences in the enrichment ability of different heavy metals in the muscles of different Granulifusus kiranus.Loligo beka and Octopus variabilis enrich Hg most significantly.In addition,Octopus vulgaris and Loligo edulis enrich Cd strongly.