摘要：This study has quantified the subsurface (groundwater, soil, sediment) water system role
for hydrological nitrogen (N) and phosphorus (P) loading to the coast and agricultural
N2O emissions to the atmosphere in a changing climate. Results for different climate and
hydrological model scenarios in the Swedish Norrström drainage basin show that the
subsurface water system may largely control a long-term increase in the coastal
nutrient loading, in particular for P, irrespectively of the realized future climate
change scenario and our uncertainty about it and its water flow effects. The results
also indicate an important subsurface water system role for current atmospheric
N2O emissions from agriculture, and an even greater role for future ones. The current
N2O–N emissions from agriculture are quantified to be about
0.05 g m−2 yr−1 over the basin surface area, or 3% of the direct N mass application on the agricultural land.
These results are consistent with recent global emission estimates, and show how the
latter can be reconciled with previous, considerably smaller subsystem emission
estimates made by the IPCC (Intergovernmental Panel on Climate Change).
