PATTERNS OF NITRATE ATTENUATION IN RIPARIAN WETLANDS

摘要

This study was conducted to determine the influence of pedo-hydrogeological settings on the potential efficiency of nitrate attenuation in wet riparian meadow. Between March and August 2000, removal of nitrogen by denitrification and by plant mowing and subsurface water inputs of nitrate were compared in two different sampling stations within the same riparian meadow. The contribution of all horizons can be quite significant to the removal of nitrogen by denitrification from the soil. Nevertheless, removal varies in time and between sampling station. On the whole of the year, denitrification removes more nitrogen than plant mowing. The quantity of nitrogen removed by denitrification on the one hand and the subsurface water inputs of nitrate on the other show a strong, opposite, vertical gradient. This implies that most subsurface water nitrate may not be affected by denitrification. The study shows how important it is to consider pedo-hydrogeological settings when estimating the removal of nitrogen by denitrification and when delimiting riparian wetland as buffer zones.