Investigation And Assessment On Heavy Metals In Industrial Shellfish Collected From The Coast Areas Of Hainan, China

With the development of industries and anthropogenic activities, heavy metalscontamination, especially in aquatic environment, becomes more and more serious.Shellfishes always contain high level of heavy metals and exceed the national foodstandard and cause food safety problems. In this study, Cu, Pb, Cd, Cr and Hgconcentrations were determined in95shellfish samples belonging to14speciescollected from the coast areas of Hainan from March2011to January2012. Thesampling sites were grouped into5zones including Wenchang, Cengmai, YangpuDongfang and Lingshui. Assessment on the heavy metals contamination in shellfishwas based on “Deleterious matters limitation in pollution-free aquatic product ofChina”. The principal objective of this study was to obtain informations on the fivemetals in shellfish along the coastal areas of Hainan and to understand the seasonal,geographic and interspecific characteristics of heavy metals in shellfish.The results were as fellows：Copper in shellfish collected from the coastal areas of Hainan was relatively low,with average content of10.50mg/kg and over standard rate of5.3%. The overstandard rates of Wenchang, Cengmai, Yangpu, Dongfang and Lingshui were10.5%,0,4.8%,7.1%and0, respectively. Geographic distribution of copper content inshellfish was higher in east and west, but lower in middle coastal area. Crassostrearivulari was the only contaminated specie. As to the seasonal pattern, a higher level ofcopper was found in samples collected in winter, in contrast, a lower level was foundin autumn.Lead content in shellfish was generally high, with average content of1.41mg/kgand over standard rate of77.9%. The over standard rates in Wenchang, Cengmai,Yangpu, Dongfang and Lingshui were84.2%,100%,85.7%,57.1%and62.5%,respectively, which gradually decreased from east to west coastal area. The speciescontaminated seriously were C. rivulari, Chlamys nobilis and Atrina pectinata. As tothe seasonal pattern, content of lead in samples gradually increased from spring to winter.The shellfish collected from the coastal areas of Hainan also be contaminated bychromium. The average content of chromium in shellfish was1.73mg/kg and overstandard rate was35.8%. The over standard rate in Wenchang, Cengmai, Yangpu,Dongfang and Lingshui were52.6%,35.3%,19.0%,42.9%and33.3%, respectively.Geographically, it was gradually decreased from east to west coastal areas. Thespecies contaminated by chromium seriously were Babylonia areolata, Ruditapesphilippinara and Perna viridis. As to the seasonal pattern, the content of chromium insamples also gradually increased from spring to winter.The shellfish was contaminated seriously by cadmium, with the average contentof1.97mg/kg and the over standard rate of40%. The over standard rate of Wenchang,Cengmai, Yangpu, Dongfang and Lingshui were52.6%,35.3%,47.6%,50%and37.5%, respectively. The samples collected in the east coastal area had a higher levelof cadmium than west. C. Nobilis and A. pectinata were the mainly contaminatedspecies. Samples collected in spring had the highest level of cadmium.Mercury content in shellfish collected from the coastal areas of Hainan weregenerally low, with the average content of0.0062mg/kg. None of the samplesexceeded the food standard.Differences of heavy metal contamination in shellfish were found in differentsampling sites. The shellfish samples collected from the coastal areas of Wenchang,Cengmai and Yangpu had higher contamination levels, with the risk index of4.11,4.60and4.05, respectively. In contrast, contamination levels of the shellfish collectedfrom Dongfang and Lingshui coastal areas were lower, with the risk index of2.06and2.25. Shellfish samples collected from Cengmai had the highest level of lead, wherethe over standard rate was above90%. The main contaminated species in this areawere C. nobilis, C. rivulari and A. pectinata. The highest cadmium level was found inthe Shellfish from Yangpu. C. nobilis and A. pectinata were main contaminatedspecies in this sampling site. C. rivulari collected from Wenchang and Yangpu had ahigher copper content than other species of shellfish. Cadmium content in C. nobiliscollected from Wenchang and Cengmai was higher than others. Highest lead content was detected in C. rivulari collected from Wenchang.The bioaccumulation of heavy metals in shellfish presented highly speciesspecific. C. rivulari tended to accumulate copper and lead. C. nobilis and A. pectinatahad a strong ability to accumulate cadmium. R. philippinara tended to accumulatechromium. Mercury in shellfish was relatively low. In contrast, mercury level in Tapesdorsatus and Scapharca broughton was higher than any other shellfish.In conclusion，the shellfish collected from the coast areas of Hainan wascontaminated by heavy metals seriously. The results of single factor analysis showedthat only17of95samples were qualified products, with the qualified rate of17.9%.Lead, cadmium and chromium were the main pollutants. C. rivulari，C. nobilis and A.pectinata were the main contaminated species, which risked a severe food safety.