Food and Agriculture Department, Science and Technology Complex, University of La Rioja, Logroño, La Rioja, Spain.
Marine and Continental Waters Program, IRTA, Sant Carles de la Ràpita, Catalonia, Spain.
PLoS One. 2019 Nov 8;14(11):e0218582. doi: 10.1371/journal.pone.0218582. eCollection 2019.
Agricultural intensification during the last century has caused river degradation across Europe. From the wide range of stressors derived from agricultural activities that impact rivers, diffuse agricultural pollution has received most of the attention from managers and scientists. The aim of this study was to determine the main stressors exerted by intensive agriculture on streams around Nitrate Vulnerable Zones (NVZs), which are areas of land that drain into waters polluted by nitrates according to the European Nitrate Directive (91/676/EEC). The study area was located in the NW of La Rioja (Northern Spain), which has some of the highest nitrate concentrations within the Ebro basin. The relationships between 40 environmental variables and the taxonomic and functional characteristics of the macroinvertebrate assemblages (which are useful indicators of water quality) were analyzed in 11 stream reaches differentially affected by upstream agricultural activity. The streams affected by a greater percentage of agricultural land cover in the surrounding catchment had significantly higher nitrate concentrations than the remaining sites. However, hydromorphological alteration (i.e. channel simplification, riparian forest and habitat degradation), which is closely linked to agricultural practices, was the main factor affecting macroinvertebrate assemblages. We suggest that "good agricultural practices" should be implemented in streams affected by NVZs to reverse stream degradation, in concordance with the European Water Framework Directive (WFD).
上个世纪的农业集约化导致了欧洲河流的退化。在影响河流的各种农业活动压力因素中，农业扩散污染受到了管理者和科学家的广泛关注。本研究旨在确定集约化农业对硝酸盐脆弱区（NVZ）周围溪流的主要压力因素，这些地区是根据欧洲硝酸盐指令（91/676/EEC）将硝酸盐污染的水排入的土地。研究区域位于西班牙北部拉里奥哈的西北部，该地区是埃布罗盆地内硝酸盐浓度最高的地区之一。在受上游农业活动不同程度影响的 11 个溪流段中，分析了 40 个环境变量与分类和功能特征的宏观生物组合（这是水质的有用指标）之间的关系。受周围集水区中更大比例农业土地覆盖影响的溪流的硝酸盐浓度明显高于其余地点。然而，与农业实践密切相关的水力学形态变化（即渠道简化、河岸林和栖息地退化）是影响大型无脊椎动物组合的主要因素。我们建议，在受 NVZ 影响的溪流中应实施“良好农业实践”，以扭转溪流退化，这与欧洲水框架指令（WFD）一致。
