ABSTRACT Human intervention in global nitrogen cycling has led to excess reactive nitrogen (Nr) flows to the environment, impacting terrestrial ecosystems as well as the quality of the atmosphere and waterbodies. This paper presents the results of a study that quantified and compared the main flows of Nr through forest land and wetlands in Latvia and Estonia using substance flow analysis approach based on data from statistics, research results, reports, monitoring programmes, data bases and expert estimations. Input and output flows to and from the forest land and wetlands both in Latvia and Estonia are well balanced, with a trend to be a Nr sink (+1.2 kT N yr−1) for Latvia and a Nr source (−6.5 kT N yr−1) for Estonia. Major input flow to the studied pools in Estonia is a soil nitrogen stock used for forest growth, while in Latvia, it is atmospheric deposition and biological fixation. Major output flow of Nr in both countries occurs via wood and peat for industrial uses. Emissions of Nr to the atmosphere and hydrosphere from forest land and wetlands are significantly lower compared to human-related emissions such as industries, energy production, agriculture, human settlements, and transport.

中文翻译：

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拉脱维亚和爱沙尼亚林地和湿地的活性氮收支

摘要 人类对全球氮循环的干预导致过量的活性氮 (Nr) 流入环境，影响陆地生态系统以及大气和水体的质量。本文介绍了一项研究的结果，该研究基于来自统计数据、研究结果、报告、监测计划、数据库和专家估计的数据，使用物质流分析方法对通过拉脱维亚和爱沙尼亚林地和湿地的主要 Nr 流量进行量化和比较。 . 进出拉脱维亚和爱沙尼亚的林地和湿地的输入和输出流量平衡良好，拉脱维亚呈 Nr 汇 (+1.2 kT N yr−1) 和 Nr 源 (−6.5 kT N yr) 的趋势−1) 爱沙尼亚。爱沙尼亚研究池的主要输入流是用于森林生长的土壤氮库，而在拉脱维亚，它是大气沉积和生物固定。两国的主要产出流是木材和泥炭，用于工业用途。与工业、能源生产、农业、人类住区和交通等人类相关的排放相比，林地和湿地向大气和水圈排放的 Nr 显着降低。