Groundwater pollution is a major global environmental issue especially in the large cities and trace metals are considered as most important aquatic pollutants. The present study is based on the measurement and characterization of various physicochemical parameters (pH, EC, TDS, DO, alkalinity, hardness, and chloride), major cations (Ca, Mg, Na and K) and selected trace metals (Sr, Li, Fe, Zn, Cu, Co, Mn, Ag, Cd, Cr, Ni, and Pb) in the groundwater of Lahore, Pakistan during summer and winter (2017–18) seasons. Groundwater is the main source of drinking water in urban areas of Lahore. Seasonal comparison of the data indicated that majority of the metals showed relatively higher concentrations during winter than summer. Most of the metals exhibited significant spatial variability during both seasons; relatively higher metal levels were found in the old settlements and thickly populated areas of the city. Average concentrations of Pb, Ni, Cd and Co in the groundwater were found to be higher than the national and international guideline values. Factor analysis and cluster analysis revealed major anthropogenic contributions of Ni, Co, Cd, Cu, Cr and Pb in the groundwater while rest of the metals showed mixed and/or natural contributions. Evaluation of human health risks for the metal contents in groundwater revealed that Pb, Co, Ni and Cd were associated with significantly higher non-carcinogenic risks (HQ_ing > 1); the calculated risk for children was considerably higher than the adults. Moreover, the carcinogenic risk associated with Ni, Cr, Cd and Pb exceeded the safe limits. The present study revealed significantly higher anthropic pollutants in the groundwater which imposed considerable risks to human; therefore, it is recommended to implement immediate remedial measures to ensure safe drinking water.

地下水污染是全球主要的环境问题，尤其是在大城市中，微量金属被认为是最重要的水生污染物。本研究基于各种理化参数（pH，EC，TDS，DO，碱度，硬度和氯化物），主要阳离子（Ca，Mg，Na和K）和选定的痕量金属（Sr，Li和，夏季和冬季（2017-18年）季节中，巴基斯坦拉合尔地下水中的铁，锌，铜，钴，锰，银，镉，铬，镍和铅的含量）。地下水是拉合尔市区的主要饮用水来源。数据的季节性比较表明，大多数金属在冬季的浓度要高于夏季。在两个季节中，大多数金属均表现出显着的空间变异性。在城市的旧居民区和人口稠密地区发现相对较高的金属含量。发现地下水中Pb，Ni，Cd和Co的平均浓度高于国家和国际准则值。因子分析和聚类分析表明，地下水中Ni，Co，Cd，Cu，Cr和Pb的主要人为贡献，而其余金属则表现出混合和/或自然贡献。对地下水中金属含量对人类健康的风险评估显示，铅，钴，镍和镉与非致癌风险显着相关（总部 因子分析和聚类分析表明，地下水中Ni，Co，Cd，Cu，Cr和Pb的主要人为贡献，而其余金属则表现出混合和/或自然贡献。对地下水中金属含量对人类健康的风险评估显示，铅，钴，镍和镉与非致癌风险显着相关（总部 因子分析和聚类分析表明，地下水中Ni，Co，Cd，Cu，Cr和Pb的主要人为贡献，而其余金属则表现出混合和/或自然贡献。对地下水中金属含量对人类健康的风险评估显示，铅，钴，镍和镉与非致癌风险显着相关（总部_ing > 1）; 计算得出的儿童风险大大高于成人。此外，与Ni，Cr，Cd和Pb相关的致癌风险超过了安全限值。本研究表明，地下水中的人为污染物明显增多，对人类构成了相当大的风险。因此，建议立即采取补救措施以确保饮用水安全。