Bioaccumulation of mercury in clams Meretrix-lyrata (Sowerby, 1825) cultured at the Bach Dang estuary: A recommendation for safe daily dosage consumption of clams in Viet Nam

Abstract

This study assessed the level of total mercury (THg) and methylmercury (MeHg) in seawater and clams Meretrix lyrata (Sowerby, 1825) during all four seasons (July 2010 to May 2011) at the Dong Bai ntertidal area in the Bach Dang estuary. The results showed that THg and MeHg concentrations of the water were under the allowable limit. THg and MeHg concentration for clams ranged from 12.5-87.9 ng/g dw and 1.1 - 24.6 ng/g dw, respectively. The highest bioaccumulation factor (BAF) of Meretrix lyrata was 303.2 for THg and 165,000 for MeHg. The recommended safe dosage for daily clam consumption depends on the season. Over an one-year period, mercury contamination in clams harvested in the Bach Dang estuary ranged from 1.4 to 38.1 g/kg bw. It is not recommended to consume too many clams in March or April.