Heavy Metals Seasonal Groundwater Contamination Levels and Pollution Indices near a Dumpsite in Enugu Southeastern Nigeria

Elevated heavy metal concentration levels observed in groundwater near dumpsites pose significant environmental and public health concern for resource managers. Consequently, the objective of this paper was to evaluate the heavy metals seasonal groundwater contamination levels and pollution indices near a dumpsite in Enugu Southeastern Nigeria using appropriate standard procedures. Findings revealed that HEI and CD values of 55.78 and 105.17 for rainy and dry seasons respectively exceeded the safe threshold value of 50, designating groundwater in the area as highly polluted and unsafe for human consumption. Though rainy season MI value of 0.372 fell below the critical value of 1, the dry season MI value (1.303) exceeded this critical value, an indication of serious heavy metal enrichment in the groundwater. CI values for both rainy and dry season samples were 5.11 and 10.17 respectively; categorizing groundwater for both seasons in the area as contaminated. Determined HPI values for all groundwater samples were greater than 100, implying severe groundwater contamination in both seasons for all sampled hand-dug well locations. NPI values for rainy season revealed Cr, Cd, Ni, Hg, and to a lesser degree Pb, Cu and Co are primarily responsible for extensive groundwater contamination in the study area. For dry season, Pb, Cr, Hg, As, and to a lesser degree, Cu, Ni, Co and Mn were implicated. Groundwater in the area was however free from Zn contamination for both seasons. To safeguard public health, this work provides resource managers with an effective tool to monitor groundwater contamination levels plan and implement land-use zoning around dumpsites, and support groundwater protection and remediation efforts.