Denitrification Potential in Geographically Isolated Wetlands of North Carolina and Florida, USA

Denitrification dynamics in geographically isolated wetlands (GIWs) may provide a link between GIWs and aquatic systems by converting N to other end products (e.g., N-2, N2O, etc.), protecting downstream waters from excessive N. We compared GIW ambient and amended denitrification rates and soil/water covariate relationships in areas of two ecoregions. The average unamended denitrification rate was 6.89 +/- 5.02 (range: 1.67-18.91) mu g N kg DW-1 (dry weight) hr(-1), and no ecoregional differences were found. Areal calculations were 0.010-0.356 g N m(-2) day(-1). Carbon amended denitrification samples decreased -18 %, while samples amended with N or N + C averaged 2730-3675 % above background levels; N + C rates were tested and did not differ between ecoregions. DW denitrification rates were correlated with soil covariates NH4, %N, and %C while ash-free DW samples were also correlated with soil TP and water TN. A tree-based classification grouped GIWs based on soil NH4 values, though the results were not conclusive. The findings suggest that GIWs embedded in areas with substantial loadings of N and P and ample C (e.g., agricultural land uses) may limit exposure of other waters to N pollution.