Riparian buffer zones are known to reduce diffuse N pollution of streams by removing and modifying N from agricultural runoff. Denitrification, often identified as the key N removal process, is also considered as a major source of the greenhouse gas @entity3810 ( @entity3727 ). The risks of high @entity3727 emissions during @entity1507 mitigation and the environmental controls of emissions have been examined in relatively few riparian zones and the interactions between controls and emissions are still poorly understood. Our objectives were to assess the rates of @entity3727 emission from riparian buffer zones that receive large loads of @entity1507 , and to evaluate various factors that are purported to control N emissions. Denitrification, nitrification, and @entity3727 emissions were measured seasonally in grassland and forested buffer zones along first-order streams in The Netherlands. Lateral @entity1507 loading rates were high, up to 470 g N m(-2) yr(-1). @entity1568 process rates were determined using flux chamber measurements and incubation experiments. @entity3810 emissions were found to be significantly higher in the forested (20 kg N ha(-1) yr(-1)) compared with the grassland buffer zone (2-4 kg N ha(-1) yr(-1)), whereas denitrification rates were not significantly different. Higher rates of @entity3727 emissions in the forested buffer zone were associated with higher @entity1507 concentrations in the ground water. We conclude that N transformation by @entity1507 -loaded buffer zones results in a significant increase of greenhouse gas emission. Considerable @entity3727 fluxes measured in this study indicate that Intergovernmental Panel on Climate Change methodologies for quantifying indirect @entity3727 emissions have to distinguish between agricultural uplands and riparian buffer zones in landscapes receiving large N inputs.

@entity3810 emission and denitrification in chronically XXXX -loaded riparian buffer zones.

@entity1568 :: ('MESH:D009584', 'Chemical') :: ['Nitrogen'] @entity3727 :: ('CHEBI:17045', 'Chemical') :: ['N2O'] @entity1507 :: ('CHEBI:48107', 'Chemical') :: ['nitrate'] @entity3810 :: ('MESH:D009609', 'Chemical') :: ['nitrous oxide', 'Nitrous oxide']
@entity1507 :: (CHEBI:48107,Chemical) :: ['nitrate']
