The concentration and chemical forms of mercury in waters of the western North Pacific

Abstract

Dissolved and particulate forms of mercury in seawater were determined. To avoid errors due to adsorption, total mercury was collected on XAD-2 resin after converting inorganic mercury to oxinate immediately after sampling. The organic mercury was trapped directly on XAD-2 resin. Both total and organic mercury adsorbed on XAD-2 resin were finally reduced to metallic mercury, which was determined by the cold vapor AAS method. In the temperature zone in the western North Pacific, total mercury is 14 ng l −1 in surface waters and 6 ng l −1 between 500 and 5,000 m. Organic and particulate mercury are 7 ng l −1 in surface waters and 2 ng l −1 between 500 and 5,000 m. Particulate forms are 3 to 10% of the total. Organic mercury comprises one-third to a half of the total. The molecular weight of organic mercury compounds was determined to be about 9 × 10 3, indicating its proteinaceous nature.