Denitrification - Conclusions
Total denitrification rates appear to be correlated with nitrate concentration and therefore largely dependent upon nitrate derived from river water.
Stream bed variables that may affect denitrification rates include sediment grain size, quantity and quality (C/N) of organic matter, the presence of periphyton and sediment hydraulic conductivity.
Greater variability in and higher average denitrification rates were observed in Sugar Creek. Controls of denitrification rates at Iroquois appear to be simpler. Denitrification rates in Iroquois were consistently lower and varied primarily as a function of nitrate concentration in the overlying water column.
More patch scale variability in stream bed factors was observed in the smaller channel (Sugar Creek) both between sites and down core, which may help explain the large variability of the measured denitrification rates.
Our results support the concept that high rates of denitrification are favored by conditions which include, low dissolved O2, a good carbon source (low C/N, periphyton), and an adequate supply of nitrate via hyporheic flow.
