Budget of N2O emissions at the watershed scale: role of land cover and topography (the Orgeval basin, France)

[摘要] Agricultural basins are the major source of N₂O emissions, with arableland accounting for half of the biogenic emissions worldwide. Moreover,N₂O emission strongly depends on the position of agricultural land inrelation with topographical gradients, as footslope soils are often moreprone to denitrification. The estimation of land surface area occupied byagricultural soils depends on the available spatial input information andresolution. Surface areas of grassland, forest and arable lands wereestimated for the Orgeval sub-basin using two cover representations: the panEuropean CORINE Land Cover 2006 database (CLC 2006) and a combination of twodatabases produced by the IAU IDF (Institut d'Aménagement et d'Urbanismede la Région d'Île-de-France), the MOS (Mode d'Occupation des Sols)combined with the ECOMOS 2000 (a land-use classification). In this study, wehave analyzed how different land-cover representations influence andintroduce errors into the results of regional N₂O emissionsinventories. A further introduction of the topography concept was used tobetter identify the critical zones for N₂O emissions, a crucial issueto better adapt the strategies of N₂O emissions mitigation. Overall, weobserved that a refinement of the land-cover database led to a 5 %decrease in the estimation of N₂O emissions, while the integration ofthe topography decreased the estimation of N₂O emissions up to 25 %.

[学科分类] 地球化学与岩石