The effects of mariculture activities on the adsorption/desorption and chemical fractionations of mercury on sediments

The aims of the present study were to investigate the effects of mariculture activities on inorganic mercury (Hg ²⁺) adsorption/desorption on sediments and the distributions of newly adsorbed Hg ²⁺ on different chemical fractionations. The adsorption amount and binding energy of Hg ²⁺ on mariculture sediment (MS) were significantly higher (p<0.05) than reference sediment (RS). This may be explained by the strong complexation role that exists between Hg ²⁺ and organic matter (OM), which derived from unconsumed fish feed and fish metabolites. The reducible Hg ²⁺ in MS was significantly lower (p<0.01) than RS, which may have been caused by the decreasing amount of iron and manganese hydroxide in MS, lead to the decrease of Hg ²⁺ bound to them. On the contrary, the residual Hg ²⁺ was significantly higher (p<0.01) in MS than RS, which suggests that newly adsorbed Hg ²⁺ was more stable in MS than RS.