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.

自1990年以来，欧洲减少的氮（N）排放量导致大气中的沉积物减少。来自四个挪威小流域的长期数据（1988-2017年）沿氮沉积，降雨和有机碳（C）的梯度分布，显示出不同的响应同期氮沉积减少25％至30％。在三个地点，减少的氮沉降导致硝酸盐向地表水的淋溶减少，而最西端的地点则没有减少，这可能是由于土壤中碳氮比低，植被覆盖差和降水高所致。总氮向河水中的损失占氮沉积的30％至50％。由于大部分流域排水良好，因此通过反硝化作用造成的损失未知，但被认为是较低的。因此，研究地点似乎继续积累氮，大概是在土壤有机质中。