Sulfur cycling in a cedar‐dominated, freshwater wetland

Rates of reduced sulfur production and quantification of S pools in anoxic peat of a New Jersey cedar swamp were determined over a 9‐month period. Short‐term anoxic incubations with 35 SO 4 2− as a tracer produced not only labeled reduced inorganic S (RIS) compounds (e.g. H 2 S, FeS, and FeS 2 ), but also labeled reduced organic S, C‐bonded sulfur (CBS), compounds. The rate of production of CBS compounds averaged 59% of the production of RIS compounds. Peat S pools for the top 10 cm were dominated by CBS (74% of total S), with RIS and ester sulfates each averaging only ∼13% of the total S. In the top 10 cm of peat, rates of reduced S production were very high relative to pool sizes, indicating that recycling of S in the peat is quite rapid. The high degree of recycling made detection of reduced S accumulation in the peat impossible over the 9‐month sampling period. Our data support an important role for SO 4 2− reduction, however, in the retention of S in the cedar swamp of McDonalds Branch.