(Supplement) Groundwater quality in Lahore Pakistan: emphasis on Arsenic and Fluoride levels

The dataset provides detailed information on the study that was conducted in Lahore's 7 major towns. The sample was taken from 472 tubewells and analyzed for major cations and anions using APHA 2012 techniques as explained herein. Besides, E.coli determination was done to check for microbial contamination. The data includes results from PHREEQC modeling of As(III)/ As(V) species and saturation indices as well as Aquachem's computed hydrochemical water facies. The WHO (2011) and EPA standards included in Aquachem identified the parameters that where in violation. Bicarbonates dominated the groundwater types with 50.21% of the samples exceeding the EPA maximum permissible limit of 250 mg/L in drinking water. Similarly, 30.51% of the samples had TDS values greater than 500 mg/L while 85.38 % of the samples exceed 10 µg/L threshold limit value of arsenic. Also, instances of high magnesium hazard values were observed which requires constant assessment if the groundwater is used for irrigation. Higher than 50% MH values are detrimental to crops which may reduce the expected yields.
The membrane filtration technique using m-Endo Agar indicated that 3.59% samples had TNC (too numerous to count) values for E.coli while 5.06% showed values higher than 0 cfu/ 100 ml acceptable value in drinking water. Any traces of E-coli in a groundwater sample indicate recent fecal contamination. Such outcomes signify presence of enteric pathogens. If the groundwater is not properly dosed with disinfectants it may cause harm to human health. It is concluded that more studies are needed and proper groundwater management implement to safeguard the lives of communities that depend solely on groundwater in the city.

本数据集详细记录了在拉合尔7个主要城区开展的相关研究数据。研究样本取自472眼管井，采用美国公共卫生协会（APHA）2012标准方法对样本中的主要阳离子与阴离子进行了检测分析，具体操作流程详见下文。此外，还开展了大肠杆菌（E. coli）检测以评估样本的微生物污染情况。数据集同时包含利用PHREEQC模拟得到的三价砷[As(III)]与五价砷[As(V)]物种形态、饱和指数结果，以及Aquachem计算得到的水化学相类型数据。依托Aquachem内置的世界卫生组织（WHO，2011）与美国环境保护署（EPA）标准，本研究识别出了超标检测参数。碳酸氢盐型地下水占主导，其中50.21%的样本中碳酸氢盐浓度超出了EPA规定的饮用水最大允许限值250 mg/L。与之类似，30.51%的样本总溶解固体（TDS）浓度高于500 mg/L，另有85.38%的样本砷浓度超出10 µg/L的限值标准。同时，研究发现部分样本的镁危害指数（MH）偏高，若将该地下水用于农田灌溉，需定期开展水质评估；当镁危害指数超过50%时，将对农作物产生毒害作用，进而导致预期产量下降。采用含麦康凯-远藤琼脂（m-Endo Agar）的膜过滤技术开展检测后发现，3.59%的样本大肠杆菌计数结果为无法计数（TNC），另有5.06%的样本大肠杆菌浓度高于饮用水标准允许的0 cfu/100ml限值。地下水样本中若检出大肠杆菌，则表明其近期受到了粪便污染，此类结果提示存在肠道致病菌污染风险。若未对该地下水采取规范的消毒处理措施，将可能对人体健康造成危害。研究最终得出结论：该城市依赖地下水作为唯一饮用水源的社区，其用水安全亟需通过开展更多相关研究、建立健全地下水管理体系加以保障。