SULFUR TRANSFORMATIONS IN SPHAGNUM-DERIVED PEAT DURING INCUBATION

Big Run Bog, West Virginia [USA] receives high .**GRAPHIC**. inputs in acid precipitation. During a closed incubation in the laboratory lasting for 125 days, concentrations of total S in surface peat did not change significantly, but in deeper (30-35 cm) peat total S decreased at a rate of 84.8 nmol g-1 dry mass day-1. In both surface and deep peat, carbon-bounded S concentration decreased (215 and 295 nmol g-1 dry mass day-1, respectively) and ester-sulphate S concentration increased (178 and 137 nmol g-1 dry mass day-1, respectively). Total inorganic S increased in surface and deeper peat (49.4 and 88.1 nmol g-1 dry mass day-1, respectively). In general, however, for the inorganic S forms (FeS2, FeS, S.degree., and .**GRAPHIC**. linear regression of concentration vs time, even when significant, explained a small proportion of total variance (R2 .ltoreq. 0.45). Results suggest that S flow through organic S compounds is dominated by the formation and mineralization of carbon-bonded S, rather than ester-sulphate S. The importance of inorganic S fractions to S flow, however, may be more important than their small pool size would suggest.