Ortmeyer Felix, Mas-Pla Josep, Wohnlich Stefan, Banning Andre
Ruhr-Universität Bochum, Hydrogeology Department, Universitätsstraße 150, 44801 Bochum, Germany.
Institut Català de Recerca de l'Aigua (ICRA), 17003 Girona, Spain; Grup de Geologia Aplicada i Ambiental (GAiA), Centre de Recerca en Geologia i Cartografia Ambiental (Geocamb), Dept. de Ciències Ambientals, Universitat de Girona, 17003 Girona, Spain.
Sci Total Environ. 2021 May 10;768:144463. doi: 10.1016/j.scitotenv.2020.144463. Epub 2021 Jan 6.
When investigating future nitrate (NO) concentrations in groundwater, climate change has a major role as it determines the future water budget and, in turn, the conditions in the aquifer which will finally have a decisive effect on NO concentrations. In this study, the different effects on water balance and NO concentration under three projected climate scenarios - RCP 2.6, RCP 4.5, and RCP 8.5 - are analysed in a water protection area in the Lower Rhine Embayment in Germany. Recharge values were calculated from downscaled precipitation and temperature data for the 21st century in a water budget that considers land use in the evapotranspiration term. Nitrate concentration evolution is estimated using recharge and expected fertilization rates with a lumped-parameter model. In order to be able to map the NO concentration, the investigation area is divided into 1000 × 1000 m cells. Each cell is assigned a specific NO input and a NO degradation capacity. Results show significant variations in NO development projected with the different climate scenarios due to different temperatures and consequently actual ET, and precipitation. Nevertheless, nitrate concentrations clearly increase in all projections. The total NO mass increases most strongly with RCP 8.5 until 2099 (by 89% compared to 2020) and least with RCP 4.5 (by 50%). Further projections show a 20% reduction in agricultural NO input can reduce NO concentrations, but insufficiently to comply with drinking water guidelines in all regions and aquifers. The model indicates that NO input loads should be defined according to future recharge variations governed by climate change. Consequently, a time-varying fertilization rate specific for each region, with their own turnover time and degradation rate, must be estimated to meet pollution environmental goals.
在研究未来地下水中硝酸盐（NO）浓度时，气候变化起着主要作用，因为它决定了未来的水量平衡，进而决定了含水层的状况，最终对NO浓度产生决定性影响。在本研究中，对德国下莱茵湾一个水源保护区在三种预测气候情景——代表性浓度路径2.6（RCP 2.6）、代表性浓度路径4.5（RCP 4.5）和代表性浓度路径8.5（RCP 8.5）——下对水平衡和NO浓度的不同影响进行了分析。在考虑蒸发散项中的土地利用情况的水量平衡中，根据21世纪降尺度后的降水和温度数据计算补给值。使用集总参数模型，根据补给量和预期施肥率估算硝酸盐浓度的演变。为了能够绘制NO浓度图，将研究区域划分为1000×1000米的网格单元。每个单元都被赋予一个特定的NO输入量和NO降解能力。结果表明，由于不同的温度以及相应的实际蒸发散和降水量，不同气候情景下预测的NO发展存在显著差异。然而，在所有预测中硝酸盐浓度均明显增加。到2099年，NO总量随RCP 8.5增加最为强烈（与2020年相比增加89%），随RCP 4.5增加最少（增加50%）。进一步的预测表明，农业NO输入减少20%可降低NO浓度，但不足以使所有地区和含水层符合饮用水标准。该模型表明，应根据气候变化导致的未来补给变化来定义NO输入负荷。因此，必须针对每个地区估算具有各自周转时间和降解率的随时间变化的施肥率，以实现污染环境目标。
