Streamwater responses to reduced nitrogen deposition at four small upland catchments in Norway
Peer reviewed, Journal article
MetadataVis full innførsel
OriginalversjonKaste, Ø., Austnes, K., de Wit, H. (2020). Streamwater responses to reduced nitrogen deposition at four small upland catchments in Norway. Ambio. doi: 10.1007/s13280-020-01347-3
Reduced emissions of nitrogen (N) in Europe have resulted in decreasing atmospheric deposition since 1990. Long-term data (1988–2017) from four small Norwegian catchments located along gradients in N deposition, rainfall, and organic carbon (C) show different responses to 25–30% reductions in N deposition during the same period. At three sites the decreased N deposition caused reduced leaching of nitrate to surface water, whereas the westernmost site showed no decrease, probably due to thin soils with low C:N ratio, poor vegetation cover and high precipitation. The loss of total N to streamwater constituted 30–50% of the N deposition. Losses via denitrification are unknown but assumed to be low, as a major fraction of the catchments are well-drained. Hence, the study sites seem to continue to accumulate N, presumably mostly in soil organic matter. Although atmospheric N deposition has declined, ambient loads might still exceed long-term sustainable levels in these vulnerable ecosystems.