Significance of aerobic and anaerobic mineralization processes of organic carbon in sediments of a shallow coastal inlet in the southern Baltic Sea

Abstract The significance of aerobic and anaerobic organic carbon mineralization was investigated in sandy mud surface sediments of the Nordrugensche Bodden (southern Baltic Sea) in differnet seasons in 1996 and 1997. By measuring oxygen penetration depths, rates of oxygen uptake, the release of manganese and iron as well as denitrification and sulfate reduction, it could be shown that sulfate reduction was the dominant respiration process in sediments sampled in summer, autumn, and winter. The ratio of the relative percentage of anaerobic to aerobic organic carbon oxidation varied between 3:1 and 15:1. In spring 1997, however, oxygen respiration was dominant. Carbon oxidation by manganese, nitrate and iron was insignificant at all times. A total benthic respiration of 0.8 to 2.3 mmol C m −2 h −1 was estimated. Between 20 and 89% of the total gross pelagic and benthic primary production was respired by heterotrophic organisms.