Comparative Assessment of Physicochemical and Bacteriological Parameters in Water Sources Near Major Dumpsites and Control Areas in Karu-Abuja and Parts of Nasarawa State

Abstract

This study evaluated the physicochemical and bacteriological parameters in water sources near major dumpsites and control areas in Karu-Abuja and Nasarawa State, to determine and compare extent of pollution using multivariate statistical analysis and indexing approach. Nine water samples from boreholes, hand-dug wells, and streams were analysed using AAS and standard methods. The concentration of Ca2+, K+, Mg2+, Cu2+, Na+, Fe2+, Zn2+, F-, SO42-, CO32-, pH, EC, COD, DO and BOD are within permissible limits, while parameters such as Pb2+ which varies from (0.44 to 0.488 mg/l), Co2+ (0.226 to 0.44 mg/l), Mn2+ (20.73 to 27.144 mg/l), Cr2+ (1.28 to 1.68 mg/l) and Cd2+ (0.09 to 0.092 mg/l) exceeded this limits. Results from Pearson correlation analysis (p < 0.05) showed positive correlations of r ranging from 0.5 to 1, indicating comparable sources of ions in the water systems. The Water Quality Index (WQI) for samples near dumpsites (177.72) indicated poorer quality compared to control areas (62.25). The study found that water samples from boreholes near control areas were suitable for domestic use with (WQI < 48), in contrast with samples from streams and hand-dug wells (WQI > 100). The water samples near dumpsites showed higher heavy metal pollution indices 188.53 compared to control sites 176.96. Bacterial analysis showed elevated coliform counts too numerous to be estimated (TNTC) in borehole samples near dumpsites, while streams had the lowest counts (9-16 cfu/ml) attributed to continuous flow. E. coli,  faecal strep, and Pseudomonas spp were absent in most samples, except for a minor presence of (02 cfu/ml) Pseudomonas spp in a Keffi hand-dug well. The decreasing dominance for major cations and anions near dumpsites and control areas are: K+>Ca2+>Cu2+>Ni2+>Na+>Mn2+>Mg2+>Zn2+>Co2+>Cr2+Pb2+>Cd2+; anions: F->SO42->Cl- and K+>Mn2+>Ca2+>Mg2+>Cr2+>Na+>Cu2+>Co2+>Zn2+>Pb2+>Cd2+>Ni2+; anions: Cl->SO42->F-respectively, attributed to anthropogenic and geogenic processes. Principal Component Analysis (PCA) accounted for over 92% of the total variance in water quality data. Hydrochemical plots identified mixed water types (Ca-Mg-HCO₃ and Ca-Mg-SO₄) with temporary hardness. The findings underscore the need for regular water quality monitoring and strategic siting of groundwater sources to mitigate contamination risks and protect public health.