| The adverse effects of residues of heavy metals（HMs）and hydrophobic organic pollutants（HOCs）on aquaculture environment and aquatic product quality have aroused wide concern.In order to understand the residual levels of HMs（Cu,Pb,Cd and Cr）and HOCs（16 PAHs and 7 PEs）in cultured Litopenaeus vannamei,the cumulative proportion of HMs and HOCs in shrimp through different exposure routes was investigated,and the exogenous input sources of HMs and HOCs in cultured environment were traced.From June 31 to September 28,2021,this study tracked and monitored the environmental media,feed,prawn,rainwater,surface runoff and other pollution sources in two ponds（Pond-1 and Pond-2）of a shrimp farm in Fengxian District,Shanghai during the whole breeding cycle.Furthermore,the cumulative contributions of HMs and HOCs in prawn from two exposure paths of breathing and feeding were quantified based on OMEGA model,and the contributions of four known pollution sources,feed feeding,influent,rainfall and surface runoff,to HMs and HOCs in the culture environment were quantified based on the principle of material conservation.The specific results are as follows:（1）Through tracking and monitoring of pond environmental media,feed and prawn within the culture cycle,it is found that HMs pollution in the culture environment is relatively serious,the concentration of Cu and Cd in overburden water exceeds the limit of Fishery Water Quality Standards,the concentration of Cu and Cr in pore water has ecological risks that cannot be ignored,and the concentration of Cr in feed exceeds the limit of Feed hygiene Standards.Pb and Cr concentrations in adult shrimp exceeded the National Standards for Food Safety,and the exceedance rates were as high as 100%and 86%.For PAHs,ΣPAHs concentration in overhanging water showed an upward trend during the culture cycle and was at a higher pollution level compared with other studies.The composition of PAHs in suspended solids,sediments and feed was similar,so it was preliminarily speculated that feed addition was one of the non-negligible sources of PAHs in culture environment.The average concentrations of Ba P andΣCHR+Ba A+Bb F+Ba P in adult shrimp were higher than the limits specified in European Commission Regulation（EU）2020/1255,and the consumption risk assessment results showed that the concentration of PAHs in this batch of shrimp had a potential risk of cancer.The concentration of PEs in the environmental medium was low,and the concentration of PEs in the feed was at a higher pollution level compared with other studies.The main PEs in shrimp were FN,FEN and DEL,and the average concentration was far beyond the limits of the Maximum Residue limits of pesticides in Food.（2）The prediction accuracy of cumulative concentrations of four metals in prawn with OMEGA model is high.High cyclic PAHs at equilibrium in shrimp with log Kow values between 4.93 and 6.70,and TET,FN,FEN,and DEL at equilibrium with stable properties were better predictors（more than 50%of predicted values were less than 20%of true values）.The cumulative contribution of pollutants in prawn from various exposure routes showed that 67%of Cu in prawn came from the assimilation of Cu in feed.In addition,the prawn mainly absorbed Cd and Pb from overlying water and Cr from pore water through respiration,accounting for 78%,53%and 66%of the total accumulated amount,respectively.FLT,CHR,Ba A,Bb F,Bk F,Ba P and DBA were absorbed from overburden water mainly through respiration,accounting for 94%,67%,57%,96%,56%,58%and 93%,respectively,and PYR and BPF were absorbed from feed mainly through feeding,accounting for 85%and 89%,respectively.For PEs,the absorption of TET from the overlying water through respiration accounted for 61%,while FN,FEN and DEL mainly accumulated in the body of shrimp through feeding,accounting for 51%,72%and 76%,respectively.It was not difficult to find that the cumulative effect of PEs decreased with the increase of hydrophobicity.The cumulative contribution of feed to PEs increased.（3）Based on the quantitative results of the conservation of materials on the sources of pollutants in the culture environment,the main source of Cu in the culture environment is feed（37%）,followed by the contribution of aquaculture water（26%）can not be ignored.The main sources of Cd,Pb and Cr are aquaculture water,accounting for 54%,84%and 52%of the total input,respectively.For PAHs,the input contribution ofΣPAHs in the pond environment was 64.5%from four known pathways,and aquaculture water and rainfall were the main sources of PAHs in the pond environment,accounting for 33 percent and 21 percent of the total input,respectively.For the seven PEs,feed supplementation dominated the total input of LCY,FEN and DEL,contributing 50.3%,62.1%and 53.3%,respectively.And among the four known pathways,feed was the main source of TET（20.2%）,FN（34.0%）and PERM（39.2%）,and influent was the main source of BF（28.5%）.The contribution of rainfall and runoff to PEs input in culture environment was low,accounting for only1.27%-16.3%of the total input.In summary,the OMEGA model was successfully applied in this study to quantify the cumulative contribution of various exposure pathways to HMs and HOCs in Litopenaeus vannamei,and the contribution proportion of pollution sources to the culture environment was quantified based on the principle of conservation of materials.The research results not only provided specific theoretical basis for optimizing the quality standards of the culture environment and improving the culture environment.It also provides early warning for quality safety and edible risks of Litopenaeus vannamei. |
