Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, P.O. Box 7050, SE 75007 Uppsala, Sweden.
Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, SE 75007 Uppsala, Sweden.
Sci Total Environ. 2021 Jun 10;772:145108. doi: 10.1016/j.scitotenv.2021.145108. Epub 2021 Feb 4.
Nutrient losses from headwater catchments (<50 km) cause eutrophication problems downstream. Catchment properties are strongly reflected in the levels of nutrient concentrations in headwater streams. Based on measurements of total and dissolved nitrogen (TN, DN) and phosphorus (TP, DP) in 235 small headwater streams, we showed that proportion of arable land in a catchment had the strongest positive effect on nutrient concentrations, with coefficient of determination (R) of 0.54, 0.64, 0.45, and 0.51 for TN, DN, TP, and DP, respectively. In contrast, increased proportion of forest and wetland led to lower nutrient concentrations in streams. The geological composition of catchments had a major influence on the soil properties. In turn, certain soil properties, such as clay content and content of aluminum (Al), an important binding agent of P, influenced losses of particulate P (PP) and DP, respectively. Consequently, by using soil properties as a link between geology and water quality, areas potentially sensitive to nutrient losses were identified by classifying bedrock categories into three geological groups. Approximately 25% of Swedish arable land was identified as potentially sensitive. Sensitive catchments were found in regions with sedimentary bedrock and showed higher concentrations of dissolved nutrient fractions even when the proportion of agricultural land was small, indicating higher background concentrations.
从源头集水区（<50km）流失的养分导致下游富营养化问题。流域特性强烈反映在源头溪流中的养分浓度水平上。基于对 235 条小源头溪流的总氮（TN、DN）和磷（TP、DP）的测量，我们表明集水区内耕地比例对养分浓度的影响最大，TN、DN、TP 和 DP 的决定系数（R）分别为 0.54、0.64、0.45 和 0.51。相比之下，森林和湿地比例的增加导致溪流中养分浓度降低。流域的地质组成对土壤性质有重大影响。反过来，某些土壤特性，如粘土含量和铝（Al）含量（磷的重要结合剂），分别影响颗粒磷（PP）和 DP 的损失。因此，通过将土壤特性用作地质和水质之间的联系，可以将基岩类别分为三个地质组，从而确定潜在的易受养分流失影响的区域。瑞典约 25%的耕地被认为是潜在敏感的。在沉积基岩地区发现了敏感的集水区，即使农业用地比例较小，也显示出更高的溶解养分分数浓度，这表明背景浓度更高。
