Denitrification in riparian buffer zones: the role of floodplain hydrology

The broad purpose of the study described here was to assess the role of den itrification in riparian zones in ameliorating groundwater pollution throug h nitrate loss, and as a potential source of nitrous oxide to the atmospher e. A suitable riparian zone was identified at Cuddesdon Mill on the River T hame floodplain near Oxford, England. Measurements were made of water and n itrate moving from arable land through the riparian zone and into the river . Techniques to measure denitrification were tested and applied, and the fa ctors controlling denitrification measured. While there was considerable po tential for denitrification at the site, this was not realized because much of the water moving off the farmland bypassed the riparian zone, entering the river directly via springs or through gravel lenses beneath the floodpl ain soil. Management of this site would not reduce nitrate leaching unless the floodplain hydrology could be substantially modified, and the main conc lusion is that nitrate buffer zones will only operate efficiently where the hydrology of the site is appropriate. Copyright (C) 1999 John Wiley & Sons , Ltd.