Sulfate reduction in the salt marshes at Sapelo Island, Georgia1

Abstract

Sulfate reduction rates were measured in stands of Spartina alterniflora at Sapelo Island, Georgia, in November 1980 by injecting tracer amounts of 35 SO 4 2− into cores, incubating overnight, and analyzing for the incorporation of 35 S into reduced sulfur compounds. Qualitatively, sulfate reduction in the Georgia marsh is very similar to that in the Massachusetts marshes we have studied: FeS 2 (pyrite or marcasite) is the major end product. Lesser amounts of soluble sulfides, iron monosulfides, and elemental sulfur are also formed. The rate of sulfate reduction (determined by the same method) is significantly lower during November in Georgia than in the Great Sippewissett Marsh in Massachusetts, 0.090 vs. 0.27 moles SO 4 2− · m −2 · d −1 in stands of short Spartina. The lower rates in Georgia may reflect a lower rate of organic carbon input by belowground production. Sulfate reduction appears to be the major form of respiration in the sediments of salt marshes in Georgia as well as in Massachusetts.