In several countries around the world, agricultural land area exceeds 70% (Uruguay 82.6%, Kazakhstan 80.4%, Turkmenistan 72.0%, Great Britain 71.7%, Ukraine 71.6% and others). This poses a serious risk of dissipating nitrates into the aquatic environment in agricultural catchments. The aim of this study was to assess the impact of land use on water quality parameters in an agricultural catchment area. It was decided to select for analysis the catchment of the Orla River (river length of 88 km, catchment area of 1,546 km2). The catchment area is predominantly agricultural in character and its entire area has been declared as an agricultural nitrate vulnerable zone (NVZ). A total of 27 survey sites were selected on the main watercourse and its tributaries. Analyses were conducted in the years 2010–2012 to determine physical and chemical parameters of water (pH reaction, conductivity, dissolved oxygen, total nitrogen, organic nitrogen, ammonia nitrogen, nitrates, total and reactive phosphorus) as well as six macrophyte metrics of ecological status assessment (MIR, IBMR, RMNI, MTR, TIM, RI). The average values of most physico-chemical parameters of water quality repeatedly exceeded limits of good ecological status, both in the Orla River and its tributaries. As many as 18 survey sites were classified as moderate ecological status, five sites as poor and only four as good ecological status. The results indicate the impact of land use in the catchment on water conductivity. Differences were observed in the concentrations of biotic components in the main watercourse and its tributaries, and in water quality in the southern part of the catchment in relation to the rest of the study area. This is probably connected with a greater share of forests and surface waters in that area.

中文翻译：

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农业集水区土地利用对低地河流水质的影响评估

在世界上一些国家，农业用地面积超过70％（乌拉圭82.6％，哈萨克斯坦80.4％，土库曼斯坦72.0％，英国71.7％，乌克兰71.6％等）。这带来了将硝酸盐消散到农业流域的水生环境中的严重风险。这项研究的目的是评估农业集水区土地利用对水质参数的影响。决定选择分析奥尔拉河的流域（河流长度为88 km，流域面积为1,546 km2）。该集水区主要是农业性质的地区，其整个区域已被宣布为农业硝酸盐脆弱区（NVZ）。在主要水道及其支流上总共选择了27个调查地点。在2010-2012年期间进行了分析，以确定水的物理和化学参数（pH反应，电导率，溶解氧，总氮，有机氮，氨氮，硝酸盐，总磷和活性磷）以及六个生态系统的大型植物指标状态评估（MIR，IBMR，RMNI，MTR，TIM，RI）。在奥尔拉河及其支流中，大多数水质的理化参数平均值均超过了良好生态状态的极限。多达18个调查点被归为中度生态状况，五个地点为差，而只有四个为良好。结果表明流域土地利用对水电导率的影响。在主要水道及其支流中观察到生物成分浓度的差异，流域南部相对于其他研究区域的水质。这可能与该地区更大比例的森林和地表水有关。