The research of heavy metal enrichment in Chlamys farreri

Abstract

An in situ experiment was performed at a Chlamys farreri culture zone of Yantai Si-Shili Bay to learn more about the heavy metal concentration in the tissues and the food organisms of C.farreri at different growth stages and to carry out food safety evaluation on C.farreri for human consumption.C.farreri samples were monthly collected from June to December in 2009.At the same time,the heavy metals were monitored in sea water,sediments and suspended solids(SS).The method for monitoring heavy metals in sea water and sediments complied with The Specification for Marine Monitoring(GB 17378—2007).By filtering 2-3 L seawater with microfiltration membrane,the samples of SS were obtained,which would be digested together with filtration membrane after desiccation,while doing a blank determination.The monitoring method complied with The Specification for Marine Monitoring(GB 17378—2007).The C.farreri were tested in conformity to Methods of Food Hygienic Analysis(GB/T 5009—2003),and 200g samples were respectively obtained as whole soft form,adductor,visceral mass and lamellibranch.The results showed that there is significant variation and selectivity of heavy metal concentration in different tissues of C.farreri,of which the enrichment coefficient of Cd is as high as 25 495,the content of Cd in adductor muscle being 1/5 of that in visceral mass,while the enrichment coefficient of Cu and Pb are 1 453 and 258,respectively.The results indicated that the enrichment process of Cd was positively correlated with the growth cycle of C.farreri,while the enrichment of Cu and Pb is in a faint-correlation with its growth cycle,which may be elucidated by the comparatively higher enrichment coefficient of Cd than those of Pb and Cu in phytoplankton,the main feeding source of C.farreri.The results from quality appraisal of C.farreri showed that the content of Cu and Pb conforms to the evaluation criteria,while the content of Cd exceeded in whole soft form,visceral mass,adductor and lamellibranch.The value of Cd content in visceral mass is 7.50 times greater than the normal,and in the whole soft form it is 3.33 times greater than the normal.In addition,a preliminary study on human body consumption standard was performed in the paper,and reference intake of C.farreri for humans was put forward.If it is eaten wholly,the weekly reference intake of the fresh will be 0.75 kg,i.e.3.0 k g including the weight of shell;if just adductor muscle is eaten,its weekly reference intake will be 1.86 kg,i.e.18.6 kg including the weight of shell.