Spatiotemporal distributions of total and methylmercury in bivalves from coastal zones of South Korea.

We measured the concentrations of total mercury (THg) and methylmercury (MeHg) in bivalves (mussels and oysters) collected from 46 sites in coastal zones of Korea in 2019 and 2020. THg and MeHg concentrations in bivalves ranged from 1.6 to 41.7 μg kg-1 and 0.8 to 26.4 μg kg-1, respectively. On average, MeHg accounted for more than about 50 % of THg showing a strong, positive, and significant correlation (r = 0.86, p < 0.001) with THg. The concentrations of THg in all samples were below the permissible threshold (< 500 μg kg-1; the Korea Ministry of Food and Drug Safety) for shellfish, whereas some sites near industrial facilities showed relatively higher Hg levels compared to non-industrial areas. The calculated provisional tolerable weekly intake indicated that THg and MeHg levels in bivalves were not significantly high concerning human health.