Chloride background values in the groundwater of Lower Saxony 1: 500.000

Background values for dissolved chloride in groundwater have been determined for the hydrogeological subregions of Lower Saxony (Elbracht et al., 2016) in order to fulfil the tasks of the EC Water Framework Directive (EC-WRRL) and the Groundwater Ordinance (GrwV). The background values of dissolved chloride include the contents that occur under natural conditions due to the contact of the groundwater with the surrounding rock matrix of the aquifer. The map shows color-differentiated the chloride background values of the hydrogeological subregions of Lower Saxony. The classification is based on the valid de minimis thresholds (GFS) of the National Working Group Water (LAWA), the limit values of the Drinking Water Ordinance (TrinkwV) and the World Health Organisation (WHO) benchmarks. By selecting a subspace you get further information (e.g. number of samples, combined sub-spaces, etc.). Background values are not current values for groundwater quality and cannot be used as such! Information on the data: The groundwater analyses used are derived from the database of the Lower Saxony Soil Information System (NIBIS). Background values are defined as the 90th percentile of the normal population of the geogenic concentration of the analysed parameter. The most up-to-date analysis of a groundwater measuring site was used to determine the background values, but no measurements dating before 2000. In the case of too low sample numbers (n < 10), lithologically similar subspaces were combined to form a common background value. The calculation of the background values followed the method for statistical evaluation of the data using the probability network of the State Geological Services (Wagner et al., 2011). Sources: ELBRACHT, J., MEYER, R. &AMP; REUTTER, E. (2016): Hydrogeological rooms and sub-rooms in Lower Saxony. — Georeports 3, LBEG, Hannover. DOI: 10.48476/geober_3_2016 WAGNER, B., WALTER, T., HIMMELSBACH, T., CLOS, P., BEER, A., BUDZIAK, D., DREHER, T., FRITSCHE, H., HÜBSCHMANN, M., MARCZINEK, S., PETERS, A., POESER, H., SCHUSTER, H., STEINEL, A., WAGNER, F. &AMP; WIRSING, G. (2011): Hydrogeochemical background values of the groundwaters of Germany as a web map service. — Groundwater 16(3): 155-162; Springer, Berlin/Heidelberg.为满足欧盟水框架指令（EC Water Framework Directive，EC-WRRL）与《地下水条例》（Groundwater Ordinance，GrwV）的履职要求，研究人员针对下萨克森州的水文地质亚区，测定了地下水中溶解态氯化物的背景值（Elbracht等，2016）。溶解态氯化物的背景值，指地下水与含水层（aquifer）围岩基质接触时，自然条件下形成的原生含量。本地图以色彩区分展示了下萨克森州各水文地质亚区的氯化物背景值，其分类依据为德国全国水工作组（National Working Group Water，LAWA）规定的有效豁免阈值（de minimis thresholds，GFS）、《饮用水条例》（Drinking Water Ordinance，TrinkwV）中的限值，以及世界卫生组织（World Health Organization，WHO）的基准标准。用户可通过选择子区域获取更多相关信息，例如样本数量、组合子区域详情等。 需特别说明：背景值并非地下水水质的实时监测数值，不可直接作为实时水质数据使用！ ### 数据详情 本数据集所用的地下水分析数据源自下萨克森州土壤信息系统（Lower Saxony Soil Information System，NIBIS）的数据库。背景值被定义为所分析参数的地质成因浓度正态总体的90百分位数。研究采用地下水监测点的最新有效分析数据计算背景值，但不纳入2000年之前的监测结果。当单区域样本数量过少（n<10）时，将岩性相似的子区域合并，以生成统一的背景值。背景值的计算遵循德国国家地质调查局概率网络的数据统计评估方法（Wagner等，2011）。 ### 参考文献 1. ELBRACHT, J., MEYER, R. & REUTTER, E. (2016): 《下萨克森州水文地质区域与亚区域》. — Georeports 3, LBEG, 汉诺威. DOI: 10.48476/geober_3_2016 2. WAGNER, B., WALTER, T., HIMMELSBACH, T., CLOS, P., BEER, A., BUDZIAK, D., DREHER, T., FRITSCHE, H., HÜBSCHMANN, M., MARCZINEK, S., PETERS, A., POESER, H., SCHUSTER, H., STEINEL, A., WAGNER, F. & WIRSING, G. (2011): 《德国地下水水文地球化学背景值的网络地图服务》. — Groundwater 16(3): 155-162; Springer, 柏林/海德堡。