Agricultural and rural land management practices can have a significant impact on the health of river ecosystems. In this study, our goal was to quantify the extent of land use influence on river water quality at two catchments in rural North Wales, Conwy and Clwyd. Stream water samples were collected bi-weekly from five sampling sites over a three-month period (September–November 2018) and analyzed in the laboratory to measure six water quality variables, namely, pH, electrical conductivity (EC), phosphorus, nitrate and ammonium concentrations, and bacterial coliform count. We then quantified their relationships with dominant land cover of the contributing catchments using two different land cover classification systems. Significant differences (p < 0.05) were observed across the sampling sites for pH, EC, nitrate and phosphorus concentration, and coliform count. Strong correlations were observed between pH and the proportion of Acid Grassland, and between nitrate levels and the proportion of Improved Grassland in the catchment. The presence of high-quality agricultural land correlated positively with nitrate and phosphorus concentrations and bacterial coliform count. Conversely, dominance of poor quality agricultural land correlated with lower levels of all the measured water quality indicators. Our results suggest that the proportion of high-quality agricultural land is a reliable indicator of stream water quality in rural catchments, most likely linked to intensive farming practices.

中文翻译：

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英国北威尔士农村土地利用土地覆盖对河流水质的影响

农业和农村土地管理做法会对河流生态系统的健康产生重大影响。在这项研究中，我们的目标是量化土地利用对北威尔士农村康威和克莱维德两个集水区河流水质的影响程度。在三个月的时间内（2018 年 9 月至 11 月），每两周从五个采样点收集溪流水样，并在实验室进行分析，以测量六个水质变量，即 pH 值、电导率 (EC)、磷、硝酸盐和铵浓度和细菌大肠菌群计数。然后，我们使用两种不同的土地覆盖分类系统量化了它们与贡献集水区的主要土地覆盖的关系。显着差异（p < 0.05) 在采样点的 pH、EC、硝酸盐和磷浓度以及大肠菌群计数中观察到。在 pH 值与酸性草地的比例之间，以及在硝酸盐水平与流域中改良草地的比例之间观察到很强的相关性。优质农业用地的存在与硝酸盐和磷浓度以及细菌大肠菌群数量呈正相关。相反，劣质农地占主导地位与所有测量的水质指标水平较低相关。我们的结果表明，优质农业用地的比例是农村集水区河流水质的可靠指标，很可能与集约化农业实践有关。