Assessing the Environmental, Health, and Food Security Implications of Heavy Metals in Irrigation Water: A Multi-Index Analytical Framework
Johnbosco C. Egbueri, Johnson C. Agbasi, Mohd Yawar Ali Khan, Sani I. Abba, Ahmad F. Turki, Mohamed ElKashouty
Abstract
Heavy metals in water systems affect water security and other sectors. Assessing the presence of heavy metals in irrigation water resources and their potential impact on soil, plant health, and food security is vital for ensuring sustainable agriculture and protecting public health. Despite the critical importance of water quality for agriculture, studies in Nigeria and in several other regions have focused solely on major chemical ions for assessing irrigation water suitability, overlooking the potential impacts of heavy metals. This study aimed to fill this significant knowledge gap by assessing heavy metal concentrations in irrigation water in southeast Nigeria and the potential toxicity implications on water security, soil quality, plant health, and food security. The research combined several techniques, including indexical, graphical, and statistical methods. The results revealed all water samples were classified as “excellent” based on composite irrigation water quality index and graphical plots. However, heavy metal analysis revealed substantial contamination and possible toxicity problems. Comprehensive pollution index (CPI) identified 42.90% of samples as polluted (range: 0.01–65.58). All samples exceeded the critical heavy metal pollution index (HPI) value of 100 (range: 177.77–46,828.46). Novel water hazard index (WHI) classified 25% of the samples as extremely toxic. Although their classifications of the samples differed, the strong correlations (r = 1, p < 0.01) and linear regressions (r2 = 1) between the CPI, HPI, and WHI demonstrated their perfect agreement and interchangeability in identifying the trends in the heavy metal pollution and water quality. Pb had the strongest correlation with all indices (r = 0.999, p < .01). Hierarchical clustering consistently separated highly polluted samples across all indices. The results showed a significant discrepancy between composite irrigation water quality and heavy metal contamination. Regular monitoring and implementation of metal-specific water treatment strategies are recommended, to ensure safe irrigation and protect food security.