The Carbon Balance of Two Riverine Wetlands Fifteen Years After Their Creation

Detailed carbon budgets from 2008 to 2010 were created for two 1-ha flow-through riverine wetlands created in 1994 adjacent to a third-order stream in central Ohio. Measurements were taken of dissolved non-purgeable organic carbon (NPOC), dissolved inorganic carbon (DIC), fine particulate organic carbon (FPOM), and coarse particulate organic carbon (CPOM). Methane emissions, soil sequestration, aquatic primary productivity, and macrophyte aboveground net primary productivity were also included in the carbon budget. The carbon budget successfully balanced inputs (1838 +/- 41 g C m(-2) year(-1)) and export/sequestration (1846 +/- 59 g C m(-2) year(-1)) with only a 0.5 % over estimation of export in relation to input; 12.8 % of the inflow was sequestered into the wetland soil. FPOM and CPOM concentrations and exports were positively correlated with hydrologic flow under most circumstances; NPOC and DIC concentrations were usually negatively or poorly correlated with hydrologic flow. In all seasons, except winter, the change of total carbon (NPOC, DIC, FPOM, and CPOM) concentration between inflow and outflow increased with increased hydrologic flow. Although carbon concentrations increased from inflow to outflow, the total surface water export of carbon is less than the inflow due to groundwater recharge from these perched wetlands.