Geochemistry of mercury in sediment of oyster areas in Sonora, Mexico

The geochemistry of mercury in sediment of oyster areas in Sonora, Mexico was studied. The study area was located at the north and central part of Sonoran coast. Mercury concentrations in the extracts were determined by cold vapor technique after reduction with SnCl sub(2). Organic matter was determined by wet oxidation method. Sediments of Sonoran coastal areas were characterized by wide variation of carbohydrate percentages and low organic contents. The highest level of mercury was found in Caborca district where sediments had 71-99% of sand and low carbonate levels. The lack of correlation between Hg:Fe and HG:organic matter suggested that organic matter was not an important factor that controlled the mercury distribution in sediments. High temperature might contribute to increased mercury concentration in sediments where oyster and clams are cultivated.