Long-term records ofnitrogen in deposition and streamwater were analysed at 30 sites covering majoracid sensitive regions in Europe. Large regions of Europehave received high inputs of inorganic nitrogen for the past 20 - 30 years, withan approximate 20% decline in central and northern Europeduring the late 1990s. Nitrate concentrations in streamwaters are related to theamount of N deposition. All sites with less than 10 kgN ha-1yr-1 deposition have low concentrations of nitrate in streamwater,whereas all sites receiving > 25 kgN ha-1 yr-1have elevated concentrations. Very few of the sitesexhibit significant trends in nitrate concentrations; similar analyses on otherdatasets also show few significant trends. Nitrogensaturation is thus a process requiring many decades, at least at levels of Ndeposition typical for Europe. Declines in nitrateconcentrations at a few sites may reflect recent declines in N deposition. Theoverall lack of significant trends in nitrate concentrations instreams in Europe may be the result of two opposing factors. Continued highdeposition of nitrogen (above the 10 kgN ha-1 yr-1threshold) should tend to increase N saturation and giveincreased nitrate concentrations in run-off, whereas the decline in N depositionover the past 5 – 10 years in large parts of Europeshould give decreased nitrate concentrations in run-off. Short and long-termvariations in climate affect nitrate concentrations instreamwater and, thus, contribute "noise" which masks long-termtrends. Empirical data for geographic pattern and long-termtrends in response of surface waters to changes in N deposition set the premisesfor predicting future contributions of nitrate to acidificationof soils and surface waters. Quantification of processes governing nitrogenretention and loss in semi-natural terrestrial ecosystems isa scientific challenge of increasing importance. style="line-height: 20px;">Keywords: Europe, acid deposition, nitrogen, saturation, recovery, water
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机译：在覆盖欧洲主要酸敏感地区的30个地点分析了沉积物中和河水中氮的长期记录。在过去20到30年中，欧洲大部分地区都接受了大量的无机氮输入，在1990年代后期，中欧和北欧的无机氮含量下降了约20％。河流水中的硝酸盐浓度与氮沉降量有关。所有沉积量少于10 kgN ha -1 yr -1 的场所中的硝酸盐浓度都较低，而所有接受> 25 kgN ha -1 < / sup> yr -1 的浓度升高。很少有站点显示出硝酸盐浓度的显着趋势。其他数据集上的类似分析也显示出很少的显着趋势。因此，氮饱和是一个需要数十年的过程，至少要达到欧洲典型的N沉积水平。一些地点硝酸盐浓度的下降可能反映了近期氮沉降的下降。在欧洲，总体而言，硝酸盐浓度缺乏明显的趋势可能是两个相反因素的结果。氮的持续高沉积（高于10 kgN ha -1 yr -1 阈值）应倾向于增加氮饱和度并增加径流中的硝酸盐浓度，而降低在过去的5至10年中，欧洲大部分地区的氮沉降应使径流中的硝酸盐浓度降低。气候的短期和长期变化会影响河水中的硝酸盐浓度，因此会产生“噪声”，从而掩盖长期趋势。地表水对氮沉降变化的响应的地理模式和长期趋势的经验数据为预测硝酸盐对土壤和地表水酸化的未来贡献奠定了前提。量化控制半天然陆地生态系统中氮保留和损失的过程是一个日益重要的科学挑战。 style =“ line-height：20px;”> 关键字：欧洲，酸沉降，氮，饱和度，回收率，水
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