The source of hydrogen sulfide in anoxic sediment

Abstract

Putrefactive hydrogen sulfide production in the upper 4 cm of sediment in two small freshwater and eutrophic Southeast Michigan, U.S.A., lakes ranged from 0.13 to 1.51 with an average of 0.46 mg S l −1 day −1. Sulfate reductive production of hydrogen sulfide at the same sites ranged from 0.7 to 3.2 with an average of 1.54 mg S l −1 day −1. Putrefactive hydrogen sulfide production represented 5.1–53% (average of 18.3–27.6%) of the total hydrogen sulfide produced at the two lakes over an April–October study period. 35S labeled substrates were used to estimate hydrogen sulfide production rates. Proteolytic bacteria averaged 2.2 × 10 4 cells ml −1 sediment whereas sulfate reducers averaged 4.8 × 10 2 cells ml −1 sediment. Putrefactive hydrogen sulfide production correlated highly with numbers of proteolytic bacteria ( r 2 = 0.84) but the correlation between sulfate reduction and sulfate reducing bacteria was low ( r 2 = 0.13). Interstitial soluble inorganic sulfate, protein and organic carbon were not closely correlated with hydrogen sulfide production rates or bacteria enumeration results. Natural substrate concentrations ( S n ) used to estimate hydrogen sulfide production were supported by kinetic bioassay results.