Multivariate Assessment of Water Quality Parameters and Health Risk of Toxic Metals in Surface Water of Crude Oil Impacted Mangrove-Creek in Southern Nigeria

Abstract

: Surface water pollution within the Niger Delta area is a threat to aquatic ecosystems. This study determined the physicochemical characteristics, toxic metal contamination, and human health risk of surface water from Goi Creek in Rivers State, Nigeria. Water samples were collected monthly from four sampling stations for a period of ten months and analysed using standard procedures. Samples were determined for physicochemical parameters and heavy metals. One-way ANOVA was used to determine the spatial significance between the stations whereas Pearson correlation, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to assess the relationships and inferred the likely contamination sources. WQI, HPI, MI and PI were used to assess the water quality status and level of metal contaminations, while ingestion-related chronic intake, HI and CR were used to estimate the likely related non carcinogenic and carcinogenic risk. The results show that there was significant difference in the concentrations of physicochemical parameters and heavy metals analysed between the stations (p <0 .05). Station 4 had the highest mean concentrations of the contaminants. The mean concentration of metals were ranked as Fe > Zn > Mn > Cu > Ni > Cr > Pb > As ≈ V > Cd > Hg. Most of the metals recorded concentrations that surpassed the guidelines used in this study. PCA and HCA results revealed positive associations between THC and most metals, indicating that petroleum-related activities were the likely source of contamination. The water samples were rated unsuitable for drinking (WQI =175.71), relatively polluted (HPI=176.05) and severely contaminated by metals (MI=65.81). Hazard index values were 2.03 for adults and 4.75 for children. The study revealed that the non-carcinogenic risk for children was higher than adult and the risk of cancer from As, Cd and Cr was above the acceptable range. The findings show that the creek has been severely impacted and recommend the provision of alternative water supply to the surrounding communities, improve pollution control strategies and continuous environmental monitoring.