Contamination of Cadmium and Mercury along the East Coast of the Gulf of Thailand: A Comparative Study Using the Green Mussel (Perna viridis), Artificial Mussel, Water and Sediment

We compared Cd and Hg concentrations in green mussel (Perna viridis) in wet and dry seasons along the Gulf of Thailand affected by different anthropogenic activities (Angsila - aquaculture, Sriracha - shipping, and Maptaphut - heavy industry). Levels of Cd in green mussels from Angsila during wet (mean ± SD 1.72 ± 0.20 µg/g dry wt.) and dry seasons (1.21 ± 0.52 µg/g dry wt.) were significantly higher than those in Sriracha and Maptaphut. Likewise, levels of Cd in artificial mussel (AM) were also highest in Angsila. Mean concentration of Hg in green mussels fluctuated only within a narrow range (0.07- 0.08 µg/g dry wt.) at all sites in the wet season, but was significantly lower in the dry season (0.03 µg/g dry wt.). Maptaphut had the highest Hg concentration in sediment during the dry season (0.17 ± 0.11 µg/g dry wt.). In contrast, level of Hg in mussel was 2-3 times higher in the wet season than the dry season at all sites.  Nevertheless, levels of Cd and Hg in mussel and sediment at all sites were still below the national Seafood/Sediment quality standards established in other countries. No significant correlation was found between level of Cd in mussels with those in AM and sediment or between sediment and AM. This research has successfully used the AM for monitoring of Cd, indicating both mussels and AM can provide a reliable estimate on Cd contamination in the aquatic environment.