Eutrophication Status of Shallow Wells in a Cretaceous Regolith Aquifer, Enugu Metropolis, South-Eastern Nigeria

The protection of groundwater quality is a critical aspect of ecosystem preservation. Nutrient (NO3-N and PO4-P) and non-nutrient (temperature and pH) assessments were carried out to study the shallow groundwater quality of Enugu metropolis in Southeastern, Nigeria. The result reveals that NO3-N and PO4-P are the main factors that endanger shallow groundwater quality safety of the Enugu metropolis. Total nitrogen (TN) and total phosphorus (TP) concentrations were observed to vary across the entire area. The mean TN and TP values for the shallow groundwater samples ranges from 14 mg/l and 93.7 mg/l and 0.720 μg/l to 6.023 μg/l, respectively. To assess the threat of eutrophication, the trophic level index (TLI), trophic state index (TSI), and eutrophication index (EI) were examined. TLI, TSI, and EI values ranged from 4.175 to 26.384, 1.855 to 3.417, and 8.32 to 20.03, respectively, indicated that the shallow groundwater varies between oligotrophic to mesotrophic.