Trace metal contamination and health risk assessment in irrigated soils: Seasonal dynamics and multivariate insights from a tropical ecosystem

Trace metal contamination in soils, arising from both natural and anthropogenic sources such as industrial wastewater irrigation, poses significant ecological and human health risks through biomagnification. This study assessed trace metal accumulation in soils irrigated with wastewater and groundwater by collecting seasonal soil samples. Metal concentrations were determined using atomic absorption spectrophotometry (Perkin-Elmer AAnalyst 800, USA), and contamination sources were characterized through statistical analyses. Results showed significantly higher concentrations of Cd, Cr, Ni, Cu, and Zn in wastewater-irrigated soil (1.93, 31.5, 40.1, 35.46 and 58.65 µgg⁻¹) compared to groundwater-irrigated soil (1.78, 11.93, 12.36, 12.06 and 21.51 µgg⁻¹). Seasonal variation analysis indicated elevated Cr, Ni, Cu, and Zn levels during the premonsoon period, except for Cd. Ecological risk indices, including contamination factor, geo-accumulation index identified Cd as the primary contributor to moderate soil contamination. Non-carcinogenic risks were mainly associated with ingestion, particularly affecting children, while inhalation posed no significant carcinogenic threats (Cd: 1.14E-07, Cr: 1.17E-05, Ni: 2.98E-07) to the local population. Statistical analyses, including correlation analysis, HCA, and PCA, were employed to elucidate inter-metal relationships, identify pollution patterns, and trace contamination sources, offering comprehensive insights into trace metal accumulation in irrigated soils. Overall, the findings demonstrate that wastewater irrigation, coupled with fertilizer and pesticide use, poses considerable risks to environmental quality and public health. These results underscore the urgent need for sustainable remediation measures, safer irrigation alternatives, and continuous monitoring to reduce contamination and protect ecosystems and communities.