Nitrogen retention versus methane emission: Environmental benefits and risks of large-scale wetland creation

摘要: Coastal eutrophication by nutrient fluxes from agricultural land to marine recipients is presently com- bated measures such as the implementation of watershed-scale wetland creation programs aimed at nitrogen removal. Such created wetlands – termed ‘nitrogen farming wetlands’ (NFWs) receive (N) loads predominantly nitrate, facilitating N removal denitrification. However, conversion soils into waterlogged area likely increase climate gas emissions, particularly methane (CH4). There thus a need evaluate benefits and risks large, watershed-scale. Here we investigate retention CH4 emission originating in South Sweden, relation between both processes, how depends on individual parameters. We combine data intensively studied reference with an extensive survey predict simple models, estimate overall process rates (large-scale effects) well spatial variation among NFWs. show that serves targeted environmental objectives (N reten- tion), comparably low. Environmental benefit risk were not correlated, may be managed independently. High cover aquatic plants was most important property suppressed net production, potentially simultaneously. Further, differences water temperature age seemed contribute production. The nationally planned (12,000 ha) could make significant contribution reduction (up 27% Swedish objective), equaling 0.04% national anthropogenic emission. (Less)