The intensification of the Baltic Sea eutrophication is associated with the increase of anthropogenic nutrients loads, mainly nitrogen and phosphorus introduced into surface waters from a diffuse, point and natural background sources. Despite the observed decreasing trends in nutrient concentrations in some parts of the Baltic Sea, eutrophication-related indicators continue to deteriorate. This accelerates harmful algal blooms and dissolved oxygen deficits resulting in severe ecosystem disturbance. The paper presents trends, insights and effects of the Urban Wastewater Treatment Directive 91/271/EEC implementation in Poland based on the nutrient riverine loads from Polish territory with particular attention given to the development of municipal wastewater treatment plants under the National Wastewater Treatment Programme 2003–2016. Environmental effects of wastewater infrastructure modernisation are investigated by using available data on the changing nutrient concentrations in the coastal water in 3 basins (Gdansk Basin, Bornholm Basin and Eastern Gotland Basin) belonging to the Polish Exclusive Economic Zone within the Baltic Sea. The results show that the decreasing trend regarding phosphorus loads reduction from municipal effluents was achieved while a stable trend with temporary increases was achieved in terms of nitrogen loads. Moreover, the investigation provides information about the potential bioavailability of discharged effluents before and after the Directive implementation by including total and inorganic forms of nitrogen and phosphorus in the analysis.

中文翻译：

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波兰沿海地区富营养化的城市废水处理指令 (91/271/EEC) 实施的趋势、见解和影响

波罗的海富营养化的加剧与人为养分负荷的增加有关，主要是从分散、点和自然背景来源引入地表水的氮和磷。尽管观察到波罗的海部分地区养分浓度呈下降趋势，但与富营养化相关的指标继续恶化。这加速了有害的藻类大量繁殖和溶解氧不足，导致严重的生态系统紊乱。本文介绍了城市废水处理指令 91/271/EEC 在波兰实施的趋势、见解和影响，基于波兰领土的营养河流负荷，特别关注 2003 年国家废水处理计划下城市废水处理厂的发展–2016 年。通过使用波罗的海波兰专属经济区 3 个盆地（格但斯克盆地、博恩霍尔姆盆地和东哥特兰盆地）沿海水中营养物浓度变化的现有数据，研究了废水基础设施现代化对环境的影响。结果表明，城市污水中磷负荷减少的趋势呈下降趋势，而氮负荷则呈现稳定趋势并暂时增加。此外，该调查通过在分析中包括总和无机形式的氮和磷，提供了有关排放物在指令实施前后的潜在生物利用度的信息。