Distribution Characteristics And Safety Evaluation Of Heavy Metals In Aquatic Animals In The Hangzhou Section Of The Qiantang River Basin

More and more attentions have been paid to heavy metal pollution due to its high toxicity and persisting pollution.When the heavy metals enter in the rivers,they can be bioaccumulated through the food chain,which can produce noxiousness effect toaquatic animals and influencethe health of occupants.In recent years,people tend to buy the aquatic products which lived in rivers,because people think them more delicious than ones live in aquaculture ponds.However,the heavy metal pollution in the muscle of aquatic animals and its safety assessment is also an inevitable problem.In this paper,we investigate and analyze thecurrent situation of heavy metals in aquatic animals collected from the Hangzhou section of Qiantang River in 2015.We determined the contents of Cu,Zn,Pb,Cd,Hg,As in the muscle of aquatic animals by the method of microwave digestion-atomic absorption and microwave digestion-atomic fluorescence spectrum.Then we analyzed and discussed the characteristics of their distribution,cultivar variation and difference in the time and space.Subsequently,the exposure risk and health risk of heavy metals were evaluated.The main results are as follows:(1)The contents of heavy metal in the muscle of aquatic animalsin Qiantang River were generallylow.However,compared with the limit values of the safety requirements for non-environmental pollution aquatic product and related articles,the contents of Pb and As were somehow higherwith the exceeding rates of 1.3%and 3.9%than the limitedstandard.Moreover,the single factor pollution index(Pi)of As in fish,the Pi of Cu,Cd in crustacea,and the Pi of Zn,Pb,As in shellfish had exceeded 0.2,showing that these heavy metals in aquatic animals had reached the criteria of ’Light Pollution’.(2)There are differences inthe muscle of aquatic animals among different species.The concentrations of Zn,Pb,As in shellfish are significantly higher than other species,the Cu,Cd in crustaceanare significantly higher than other species,and the concentrations of Hg in fish is slightly higher,indicating that fish is a little bit saferin terms of heavy metals.Metal pollution index(MIP)shows that the heavy metal pollution of different species are in an descending order of shellfish>crustacea>fish.(3)There are differences inthe muscle of aquatic animals among different times.The contents of heavy metals in the muscle of aquatic animals collected in June are significantly higher than those collected in March and/or September.Water temperature is supposed as a key factor which could be having an influence on the heavy metal accumulation and its seasonal variations.(4)The statistics results showed that the contents of heavy metals in Qiantang River had no significant difference(P>0.5)among sampling areas,which showed minor differences in spatial distribution.However,the contents of Pb in the muscle of fish had obvious variation with sampling areas,which may be mainly caused by the waste water and atmospheric deposition of nearby factories.(5)Assessment results showed that the dietary exposures of heavy metals in the muscle of aquatic animalsin Qiantang River were lower than PTWI,indicating the dietary exposures of heavy metalsoverall in a safe rangeof theaquatic animals,namely no harm,to health.(6)Health risk assessments demonstrated that the heavy metal intake of aquatic animals had little health risk to consumers,so it is safe for us to eat.However,we realized that contribution rate of As to health risk was largest,and As was thought to have non-carcinogenic risk,so that more attention should be paid to its health risk.