Application of indexical models in assessing ecological-health risk and heavy metal pollution in Enyigba-Ameka, Nigeria

Assessment of the ecological-health risk and heavy metal pollution in drinking water was carried out in the Enyigba-Ameka Pb–Zn mining region in order to establish present level of heavy metal enrichments. Thirty-five water samples were collected from various source of drinking water in two seasons (dry and wet) and analyzed according to the American Public Health Association (APHA) standard. Data was interpreted using nine indexical models. Water quality index (WQI) values obtained showed that 9%, 20%, and 71% of the samples indicated “moderately polluted water, polluted water, and excessively polluted water” respectively during dry season and 14%, 37%, and 49%, representing “moderately polluted water, polluted water, and excessively polluted water” respectively during wet season. Synthetic pollution index (SPI) values for dry season were 9%, 17%, 48%, and 26% indicating slightly polluted water, moderately polluted water, highly polluted water, and unfit respectively for drinking purposes while for wet season, 6%, 28%, 43%, and 23% representing slightly polluted water, moderately polluted water, highly polluted water, and unfit respectively for drinking purposes. Hazard quotient (HQ) revealed that cadmium (Cd) was the major heavy metal influencing undesirable health conditions in both the adult and children populations in both seasons. Contamination index (CI) classified 35 water samples as low contamination in dry season and 28 in wet season while heavy metal evaluation index (HEI) classified 35 samples as low contamination in both seasons. The study’s findings provide insights into contamination by heavy metals for the protection of human health and water supply in the Enyigba-Ameka Pb–Zn mining region.