Assessment Of Sediment Heavy Metal Pollution And Ruditapes Philippenarum Response Research In Maluan Bay

Heavy metals in the sediments of Maluan Bay,Xiamen were studied.First,the degree of pollution and geochemical characteristics of the entire sediments in the selected sampling sites were analyzed.Then,biomarkers and traditional sediment analysis were combined to study heavy metals in the sediments about their solid/liquid phase and the migration process between organisms,biological factors influencing the effectiveness and causes,and their relationshipsbetween toxic effects of exposure.1 Pollution characteristics of sedimentin sampling sitesEight sampling siteswere set based on their functionsafter extensive investigations of the selected area,including discharge outlet,aquiculture area,fishermen area and so on.Physical and chemical properties and the contents of heavy metals in overlying water and pore water were analyzed.Sediment's physical and chemical properties,simultaneously extracted metaland different species of particle heavy metal were also investigated.Various assessments on heavy metal pollution in sediments of Maluan Bay were conducted.The primary resultsare as follows:Only the concentration of Pb in overlying exceeded the second level in the national seawater quality standards.The content of heavy metal in Pore water is greater than inoverlying water,whichexceeded the second level inthe national seawater quality standards.The contentof heavy metal in sediment is more than valueset by the marine sediment quality criteria of China.The results show that the first discharge outlet was the most polluted area: the contents of Cr,Cd and Cu in sedimentsof study sites exceeded the first level of the marine sediment quality criteria,while Zn and Pb were more than the second level in the criteria.The sequence of heavy metal pollutionisthe first discharge outlet,its surrounding aquiculture area(ML1,ML2)and fishermen area(ML7,ML8)>sewage treatment plant export and its surrounding aquiculture zones(ML5,ML6)> the second discharge outlet and its surrounding aquiculture area(ML3,ML4).Simultaneously the extracted metal and different species of particle heavy metalin sediment were consistent with theresults.2 The accumulation and distribution of heavy metals in Ruditapes philippenarum(R.philippenarum)and its biomarker responsesIn situ exposure experiments of the R.philippenarum in Maluan Bay,the contentsof heavy metals inkey organizations and subcellularofthe R.philippenarum wereanalyzed.Moreover,the biomarker responses in the bodywere confirmed and the influencesconducted bythe sediment heavy metal to the R.philippenarum were assessed to realize the comprehensivemonitoringto the heavy metal pollutionin sediments.The primaryresultsareas follows:The in situ R.philippenarum exposure experiments show that compared to the visceral mass,pleopod and mantle,gillsare the main enrichmentorganizationof heavy metals,especially for Cd.The subcellular partitioning of metal within R.philippenarum biological detoxified metal(BDM)played an important role in the storage of Cd and Zn,while Cr,Cu and Ni are dominated by biological active metal(BAM).The contents of SOD?GPX and MDA were correlated to the accumulations of Cu,Zn and Cr,while catalase activity correlated to accumulation the ofPb.GST activity is the phase II of the biomarkersinfluenced by Cr(r = 1.000,p < 1.000),Cd(r = 1.000,p < 0.05),and Ni(r = 0.999,p<0.05).Metallothionein(MT)content was no significant correlation(p > 0.05)with heavy metal contents in R.philippenarum.Correlational analyses between heavy metals(simultaneously extracted metal and acid-soluble fraction heavy metal)in sediments and R.philippenarum(heavy metal inside R.philippenarum and biomarker responses)were conducted.Theresults show that both simultaneously extracted metal and acid-soluble fraction heavy metal can affect the heavy metal accumulation in R.philippenarum,and their affections were contrary.Cr(r=1.000,p<0.05)and Cu(r=0.999,p<0.05)effected superoxide dismutase(SOD)activity.Glutathione transferase(GST)activity correlated to Ni(r=1.000,p<0.01),Cu(r=0.999,p<0.05)and Zn(r=-1.000,p<0.01).Metallothionein(MT)content correlated to Cd(r=-0.998,p<0.05),Cu(r=-0.999,p<0.05)and Zn(r=0.999,p<0.05).