Sulfate reduction rates in Georgia marshland soils

Abstract

Sulfate reduction rates in Sapelo Island Spartina marsh soils were assessed by a radiometric method. There was a significant linear correlation (r = 0.93) between the H₂ ³⁵S produced and incubation period, and the regression line passed close to the origin. Sulfide reduction rates for the topmost 35 cm of soil in the short and tall Spartina zones were 62.3 and 201 mmol sulfide/m² /lb day, respectively. To reduce sulfate at these daily rates, the sulfate‐reducing bacteria would require a maximum of 67 and 36% of the organic carbon produced by the summer crops of short and tall Spartina, respectively. In both zones, highest rates occurred in the 0‐ to 5‐cm layer. In the short Spartina zone, 80% of the sulfate reduction in the topmost 35 cm occurred in the 0‐ to 5‐cm layer, whereas a value of 29% was found for the same situation in the tall Spartina zone. In the topmost 10 cm of the short Spartina zone, some sulfate appeared to be immobilized as organic sulfate.

Notes

Present Address: CSIRO Coastal Ecology Program, Box 20, North Beach, Western Australia 6020.