Appraisal of sources, pollution and risks of some metals in soil and water using geochemical and multivariate statistical approach, eastern Niger Delta, Nigeria

The sources and contamination level including human health risks in soil, surface water and groundwater by some heavy metals in the Niger Delta area, Nigeria were investigated. Fifty-four soil and forty-two water samples were analyzed for physical and chemical parameters and heavy metals based on standard methods. Indexed and statistical techniques were applied in order to assess the extent of contamination from saltwater intrusion and metals. Results revealed that the soils were acidic with electrical conductivity > 40 mg/kg, suggesting effect of seawater. High concentration of some metals characterized soil. The ratios Na+/Cl−, Cl−/HCO3− and scatter plots of Cl− versus EC suggest contamination of the water by sea water. Different contamination indices indicate that more than 50% of the water samples were contaminated. Significant positive correlation suggests common sources, while significant negative correlation suggest a different sources for the metals. Factor analysis indicate that the metal contamination was due to different sources. Risk assessment through hazard quotient and hazard index via soil exposure pathway were < 0.1, suggesting minimal risk in the Niger delta region. Average HQ and HI values through water ingestion exposure route were > 1, suggesting adverse noncarcinogenic health risk. The cancer risk level in water for Cd and Cr exceeded the recommended value, compared to soil. In conclusion, most of the water samples if consumed continuously may constitute health risk.