Enrichment of Heavy Metals in Growth Period of Cage Cultured Carp(Cyprinus carpio) from the East Dongting Lake

Samples of cage cultured carp(Cyprinus carpio) in different growth periods were collected in the East Dongting area from February to July 2012.The w(Pb),w(Zn),w(Cd),w(Cu) were measured by the atomic absorption spectrophotometry in water samples,fodders and the gills,livers and muscles of carp.The results showed that the water quality belonged to level Ⅰ according to the Environmental Quality Standards for Surface Water(GB 3838-2002).The mass fraction of heavy metals in the fodder was relatively higher,which made the fodder become the main possible source of heavy metals pollution in carp.The w(Pb) and w(Cu) increased with the fish growth.In the gills,Pb were not detected(nd) while the w(Cu) were 0.143-0.703 mg/kg.In the livers,w(Pb) and w(Cu) ranged in 0.006-0.181 mg/kg and in 0.625-6.177 mg/kg respectively.In the muscles,w(Pb) and w(Cu) were nd-0.034 mg/kg,nd-0.161 mg/kg respectively.During the growth of the carp,the w(Zn) and w(Cd) increased firstly and decreased later.During the first to the 4th month,the w(Zn) in gills,livers and muscles increased from 40.121,21.302,2.032 mg/kg to 258.964,146.155,18.011 mg/kg respectively.Similarly,the w(Cd) increased from 0.015,0.031,0.003 mg/kg to 0.078,0.151,0.021 mg/kg respectively in gills,livers and muscles.After four months,the w(Zn) in gills,livers and muscles declined gradually to 173.182,104.219,5.490 mg/kg respectively while the w(Cd) declined to 0.037,0.111,0.018 mg/kg at the same time.During the whole growth process of the fish,the liver was the main enrichment site for Pb,Cd and Cu while the gills were the main enrichment site for Zn.The mass fraction of heavy metals in muscles was the lowest among all tissues.All these three parts strongly correlated.