The important role of wetland conservation and restoration in nitrogen removal across European river basins

Abstract In Europe, excessive inputs of nitrogen threaten ecosystems and public health. Wetlands act as natural filters, removing excess nutrients and protecting downstream waters. Using high-resolution data on nitrogen surplus and wetland distribution, we estimate that existing European wetlands remove 1,092 ± 95 kt of nitrogen per year. Restoring 27% of wetlands historically drained for agriculture (3% of land area), targeted in high nitrogen input areas, could reduce current nitrogen loads to the sea by 36%, but with potential costs to agricultural productivity. A more efficient strategy targets wetland restoration on farmlands projected to be abandoned by 2040, yielding a 22% load reduction and enabling major rivers such as the Rhine, Elbe and Vistula to meet water quality targets with minimal agricultural impact. Our findings highlight wetland restoration as a cost-effective, policy-relevant solution that, if spatially targeted, can deliver major water quality improvements while supporting the European Union’s broader goals on climate, biodiversity and agricultural sustainability.