Investigation And Analysis On Content Of Heavy Metals (Lead And Cadmium) In Maricultured Shellfish From Zhejiang Coast

Zhejiang is traditional province on shellfish marine-culture.However,withprogressively land-based sources of heavy metal pollution,which is influencing andexacerbating coastal marine environment of Zhejiang,and then the shellfish living hereinevitably suffers increasing heavy metal pollution.Studying on investigation and analysis on content of heavy metals (lead and cadmium)in mainly maricultured shellfish from Zhejiang coast during2010～2013, it sampled anddetermined content of lead and Cadmium of shellfish from primary shellfish cultivatingareas in Zhejiang near-shore.The investigated shellfish cultivating areas here were YueqingBay, Sanmen Bay under Sanmen County, Yanpu Bay under Cangnan County and ShengSiGouqi Island,including Sinonovacula constricta Lamarck, Crassostrea plicatula (Gmelin),Arca Anadara granosa linné, Cyclina sinensi and Mytilus edulis Linné.Owing to the lagging pre-treatment process of National food safety standard,and inwhich the details of Graphite Furnace Atomic Absorption Spectrometry lacked samplepertinency, for the purpose to ensure the determination quality of above samples,we choseMicrowave Digestion for pre-treatment of shellfish samples and optimized the method ofGraphite Furnace Atomic Absorption Spectrometry (GF-AAS) according to the actualdemand for shellfish samples determination. The results of analysis demonstrated that bythis optimized method, the correlation coefficient r of standard curve could reach0.999.Also by this method, the determination results of arbitrarily chosen shellfishsamples,Sinonovacula constricta Lamarck and Mytilus edulis Linné showed highparallelism and stable recovery rates, the average recovery rates could reach92～96%.Moreover, the high accuracy and precision of this method was also tested by nationalstandard substance(Mussel, GBW08571). It showed that the six parallel determinationresults were all referred to permissible error range of measured value,which successfullyachieved the goal of quality control.Hence, with excellent sensitiveness and stablerecurrence, and convincing accuracy and precision, Microwave Digestion as pre-treatmentprocess and optimized Graphite Furnace Atomic Absorption Spectrometry(GF-AAS)method, is suitable for precise determination of lead and cadmium content inshellfish samples．By the results of lead and cadmium content determination,we commented currentquality of investigated maricultured shellfish with Non-environmental Pollution Aquatic Products standard, Marine biological quality standard and single factor contaminant indexassessment.The comment on shellfish from Yueqing Bay indicated that Pb content ofSinonovacula constricta Lamarck was higher than that of others.And Arca Anadaragranosa linné and Crassostrea plicatula (Gmelin) were of more powerfully cadmiumaccumulation ability.And Cyclina sinensis was of weakest accumulation ability for leadand cadmium,which revealed that Cyclina sinensi was of slightest pollution by lead andcadmium.But the cadmium content of Arca Anadara granosa linné was severely beyondNon-environmental Pollution Aquatic Products standard limit,which suggested the healthrisk by consuming Arca Anadara granosa linné.By comparative study on content scope,average content,exceeding rate beyondNon-environmental Pollution Aquatic Products standard limit,and the proportion of thefirst level in Marine biological quality standard, average Pi value for Sinonovaculaconstricta Lamarck samples from shellfish cultivating area of Sanmen Bay under SanmenCounty, Yanpu Bay under Cangnan County and Yueqing Bay in past4years, it found thatPb proportion of the first level in Marine biological quality standard and all the measuresof Cd for Sinonovacula constricta Lamarck from Yanpu Bay under Cangnan County wasbetter than others.It verified that environmental quality of shellfish cultivating areas atYanpu Bay under Cangnan County was highest.With analysis and assessment of content for lead and cadmium in Mytilus edulis Linnésamples from ShengSi Gouqi Island, it showed that Mytilus edulis Linné samples here wasof slight lead pollution,but of relatively serious cadmium level,to which we should paymore attention now.