A SIMPLE METHOD FOR ESTIMATING NITRATE REMOVAL FROM FLOODWATERS IN RIVER MARGINAL WETLANDS

Soil cores from river marginal wetlands in the UK, France and Ireland, sampled and contained within PVC piping, were flooded with nitrate-N enriched water. Half of the cores were sterilized prior to flooding to destroy the denitrifying bacteria. The change in nitrate-N concentrat ion in the floodwater was measured over time. It is argued that the ob served nitrate depletion rates (from 0.4 to 2.3 kg/ha per day) may be identified with microbially-mediated denitrification. The results show the method to be a simple and direct procedure for the assessment of spatial variation in nitrate-sink capacity. The depth of the denitrify ing layer at the soil-water interface was confirmed to be of the order of a few mm.