Department of Environmental Sciences, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova 39, 1000 Ljubljana, Slovenia.
Department of Environmental Sciences, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
Sci Total Environ. 2019 Jan 1;646:1588-1600. doi: 10.1016/j.scitotenv.2018.07.245. Epub 2018 Aug 4.
The Ljubljansko polje aquifer, which is the main supply of drinking water for the local population in Ljubljana, Slovenia is highly vulnerable to anthropogenic pollution. In this study, the geochemistry of major constituents including nitrate concentrations and the dual isotopes of nitrate were used to ascertain the spatial distribution of processes and nitrate sources in the groundwater from seven wells at three different water supplies: Kleče, Hrastje and Jarški prod. The groundwater is of the Ca-Mg-HCO type approaching equilibrium with respect to dolomite and are moderately supersaturated with calcite. The groundwater nitrate concentrations ranged from 5.32 to 50.1 mg L and are well above the threshold value for anthropogenic activity (3 mg L). The δN values ranged from 1.4 to 9.7‰, while δO values were from 6.3 to 34.6‰. Based on isotope mixing model three sources of nitrate were identified: atmospheric deposition, fertilizers and soil nitrogen. At Kleče 8, Kleče 12 and Jarški prod 3 the low δN and high δO values result from pristine nitrate sources, while in Hrastje 3 and Kleče 11 equal amounts of nitrate derived from soils with mixed fertilization and sewage. The data also indicate that the main sources of high nitrate concentrations in groundwater are from fertilizers and sewage-manure (comprising up to 64%). Such levels occurred in the Hrastje and Kleče 11 wells where precipitation is the main source of groundwater. Nitrate derived from atmospheric deposition accounted for approximately 10% of the nitrate in the groundwater. The message from this study is that to reduce the nitrogen load and improve water quality will involve containment and the careful management of sources from urban and agriculture inputs such as sewage-manure and fertilizers.
卢布尔雅那波列含水层是斯洛文尼亚卢布尔雅那当地居民的主要饮用水供应源，极易受到人为污染。在这项研究中，主要成分的地球化学特性（包括硝酸盐浓度和硝酸盐的双重同位素）被用来确定来自三个不同水源（克莱采、赫拉斯特耶和雅尔斯基产品）的七个井中的地下水的过程和硝酸盐来源的空间分布。地下水属于 Ca-Mg-HCO 型，接近与白云石达到平衡，并与方解石呈中度过饱和状态。地下水中的硝酸盐浓度范围为 5.32 至 50.1mg/L，远高于人为活动的阈值（3mg/L）。δN 值范围为 1.4 至 9.7‰，而 δO 值范围为 6.3 至 34.6‰。基于同位素混合模型，确定了硝酸盐的三个来源：大气沉降、肥料和土壤氮。在克莱采 8 号、克莱采 12 号和雅尔斯基产品 3 号，低的 δN 和高的 δO 值来自原始的硝酸盐源，而在赫拉斯特耶 3 号和克莱采 11 号，来自混合施肥和污水的土壤的硝酸盐数量相等。数据还表明，地下水高硝酸盐浓度的主要来源是肥料和污水粪便（占比高达 64%）。这种情况发生在赫拉斯特耶和克莱采 11 号井中，降水是地下水的主要来源。大气沉降产生的硝酸盐约占地下水硝酸盐的 10%。这项研究的结论是，为了减少氮负荷和改善水质，需要对城市和农业投入（如污水粪便和肥料）的来源进行控制和谨慎管理。
