The process of microbial sulfate reduction in Sediments of the coastal zone and littoral of the kandalaksha Bay of the White Sea

Microbiological and biogeochemical investigations of the coastal zone and the littoral of the Kandalaksha Bay of the White Sea were carried out. The material for investigations was obtained in the series of expeditions of the Institute of Microbiology, Russian Academy of Sciences, in August 199.9, 2000, 2001, and in March 2003. The studies were conducted on the littoral and in the water area of the Kandalaksha Preserve, the Moscow University Belomorsk Biological Station, and the Zoological Institute Biological Station, Russian Academy of Sciences. Sediment sampling on the littoral was carried out in the typical microlandscapes differing in the sediment properties and macrobenthos distribution. The maximal sulfate reduction rate (SRR) was shown for the shallow part of the Chernorechenskaya Bay (up to 2550 mug S/(dm(3) day)) and in the Bab'ye More Bay (up to 3191 mug S/(dm(3) day)). During the winter season, at a temperature of -0.5 x 0.5degreesC, the SRR in the sediments of the Kartesh Bay was 7.9 x 13 mug S/(dm(3) day). In the widest limits, the SRR values varied in the sediment cores sampled on the littoral. The minimal values (11 mug S/(dm(3) day)) were obtained in the core samples on the silt-sandy littoral. The littoral finely dispersed sediments rich in organic matter were characterized by high SRR values (524-1413 mug S/(dm(3) day)). The maximal SRR values were shown for the sediments present within the stretch of decomposing macrophytes, in local pits at the lower littoral waterline, and in the mouth of a freshwater stream (51-159 mg S/(dm(3) day)). A sharp difference in the level of H2S production in the type microlandscapes was shown. The average hydrogen sulfide production in finely dispersed sediments constituted 125 mg S/(m(2) day); in stormy discharge deposits, 1950 mg S/m(2) day); in depressions under stones and in silted pits, 4300 mg S/(m 2 day). A calculation made with regard to the area of microlandscapes with increased productivity shows that the daily H2S production per 1 km(2) of the littoral (August) is 60.8 to 202 kg S/(km(2) day), while the organic carbon consumption for sulfate reduction per 1 km(2) of the littoral is 46 to 152 kg C-org/(km(2) day).