Evaluation of General Patterns of Heavy Metal Contamination in Water Sources Across Different Geographic Areas Across Pakistan

Abstract

Background: Heavy metal contamination of drinking water poses a persistent public health concern, particularly in rapidly industrializing regions. In Pakistan, increasing industrial discharge and urban expansion have raised concerns regarding the safety of groundwater and surface water sources used for domestic consumption. Objective: To evaluate the distribution patterns and concentration levels of selected heavy metals in drinking water sources within the Industrial and Urban Core of Punjab and to assess variations based on water source type and proximity to industrial activity. Methods: A descriptive cross-sectional study was conducted over four months, analyzing 72 water samples collected from groundwater and surface water sources located within 5 km of industrial zones. Samples were preserved and analyzed using atomic absorption spectrophotometry to quantify lead, cadmium, arsenic, chromium, and nickel concentrations. Descriptive statistics were calculated, and comparisons between water source types were performed using independent t-tests and one-way ANOVA. Pearson correlation analysis assessed relationships among heavy metals. Results: Lead (0.018 ± 0.009 mg/L), arsenic (0.021 ± 0.011 mg/L), and cadmium (0.006 ± 0.003 mg/L) frequently exceeded recommended safety limits, with exceedance rates of 61.1%, 54.2%, and 47.2%, respectively. Groundwater sources demonstrated significantly higher concentrations of all assessed metals compared to surface water (p < 0.05). Moderate positive correlations were observed among several metals, particularly between lead and arsenic (r = 0.61) and chromium and nickel (r = 0.52). Sites located closer to industrial areas showed significantly elevated composite contamination levels (p = 0.012). Conclusion: The findings indicate substantial heavy metal contamination in drinking water sources within an industrialized urban region, particularly affecting groundwater supplies. Strengthened environmental monitoring and regulatory enforcement are essential to mitigate long-term health risks