Assessment of the Health Risk, Aesthetic and Agricultural Quality of Rainwater, Surface Water and Groundwater in the Shale Bedrock Areas, Southeastern Nigeria

Fifty water samples from rain, ponds, rivers, streams, hand dug wells and boreholes were collected from various locations within the shale bedrock terrain in parts of Southeastern Nigeria. The water samples were analysed for physiochemical parameters and heavy metals. The aim of the study was to assess the regional quality of these water bodies with respect to human health risk, aesthetic value and agricultural quality. The study also determined the sources of metals based on Pearson's correlation and R-mode factor analysis. The results showed that correlation analysis revealed the degree of relation between the different parameters, while the R-mode factor analysis revealed five factors that were consistent with geological, environmental and human activities. In terms of human health, hazard quotients (HQ) and hazard indices for potentially toxic elements were less than 1.0 indicating that the non-carcinogenic risks due to drinking water in the area are negligible. However, the HQ for Pb in borehole water was >1. Arsenic cancer risk through drinking water in the area did not exceed the acceptable risk of 1 in 10000 (0.0001) for regulatory purposes. In respect of aesthetic value, all the parameters considered including turbidity, hardness, Al, Fe and SO4 showed variability in the level of acceptability for the different water sources. Magnesium Hazard showed that the water is suitable for livestock, whereas the enhanced values of electrical conductivity, sodium adsorption ratio, percent Sodium, Kelly index and total hardness at most locations suggested that the different water sources are suitable for domestic and agricultural purposes. On the basis of a water quality index, most of the water samples fell within excellent and good categories. From this study, the most pressing water problem in the area is water for domestic use and agriculture use in the dry season. The most problematic source of water regarding health risk, nitrate content and aesthetic value included water from borehole, hand dug well and stream, while pond and river water samples are the most problematic considering agricultural use. Generally, water from hand dug wells and boreholes is the most problematic in terms of overall quality.