Removal of solids, nitrogen, and phosphorus in the Cache River Wetland

Mass flux measurements collected between April 1987 and September 1990 at the upstream and downstream boundaries of the Cache River Wetland (CRW), a bottomland hardwood forest in eastern AR kansas, were used to estimate long-term, average removal efficiencies (RE, %) for inorganic suspended solids (ISS), total nitrogen (TN), and total phosphorus (TP). The observed removal efficiencies were used with a steady-state, first-order removal model to compute removal rate constants. Detention time of the CRW was determined with a time-varying, two-dimensional, depth-averaged, numerical Bow and transport model. The computed average detention time of 5.02 da was close to the average hydraulic retention time of 5.15 da, justifying the plug flow assumption of the model. The removal rate constants estimated from the CRW data for ISS, TN, and TP were 0.066 m/da, 0.048 da(-1), and 0.0058 m/da (2.1 m/yr), respectively. The denitrification rate constant estimated for the CRW was 0.24 da(-1). These rate constants are in general agreement with values obtained from the literature.