Methanogenesis in sediments of the polluted lower reaches of the Tama River.

Abstract

Seasonal changes of methanogenesis were studied in sediments of three stations along the water course in the polluted lower reaches of the Tama River, Japan. Methanogenesis was the highest at the upper freshwater station and decreased near the river mouth, in accordance with increasing concentration of sulfate in interstitial water. At all stations methanogenesis increased from spring to summer and decreased in winter except for once at the lowest station. The sediment layer which showed the highest activity tended to become deeper downstream. Effects of additions of substrates or inhibitors on methanogenesis in sediment slurries suggested that methanogenesis was competitively inhibited by sulfate reduction in sediments containing high sulfate concentrations, but the degree of the inhibition decreased in sediments with low sulfate concentration.