The speciation of mercury in sediments from Kagoshima Bay and Minamata Bay, southern Kyusyu, Japan, by fractional extraction/cold-vapor AAS.

Two procedures were used for the speciation of mercury in marine sediment. One procedure had been proposed for the differential determination of organic mercury, mercury (II) oxide and mercury (II) sulfide in sediments, based on their successive extraction, followed by a cold-vapor atomic absorption spectrometric determination. In this method, organic mercury was first extracted by shaking a sediment sample with chloroform. Another procedure had been proposed for the differential determination of inorganic and organic mercury in environmental and biological materials. In the latter procedure, mercury was first extracted by shaking a sample with 1 M hydrochloric acid containing 3% sodium chloride in the presence of copper (I) chloride. In order to separate organic mercury from inorganic mercury, the extract was shaken with chloroform to extract only organic mercury. In the current investigation, they were suggested that not only methylmercury, but also mercury bound with organic matter in the sediment, could be determined as organic mercury by the former procedure, and that the organic mercury determined by the latter procedure corresponded to methylmercury. These procedures were applied to the speciation of mercury in sediments from Minamata Bay and Kagoshima Bay. In sediments taken in the vicinity of submarine fumaroles in Kagoshima Bay, 7∼37% of the total mercury existed as organic mercury, which was considerably higher than 1∼4% in the Minamata Bay sediment.