Quantifying nitrate pollution sources and natural background in an equatorial context: A case of the Densu Basin, Ghana

Abstract

The study assesses the extent of nitrate pollution in the Densu Basin because of itspredominance in agriculture and urbanized vicinities by employing robust techniques for estimating both the natural background and human-induced concentrations. Statistical methods used to estimate these concentrations are the pre-selection method, graphical approach (probability plot), non-parametric approach (kernel density estimation), and parametric approach (Gaussian mixture model). The study shows that the Gaussian mixture model is robust enough in determining the spectral distribution and clustering of the NO3-N concentration in the basin. It estimated the natural background and human induced concentration at 1.7±1.3 mg/L and 9.8±5.6 mg/L, respectively. The results show that the natural background concentration in the basin is more dominant and hence, conducive for drinking. It’s revealed that 26% of anthropogenic sources have leaked into the natural groundwaters of the Basin. The data suggest multiple sources of NO3-N concentration in the groundwater.