SPATIAL-TEMPORAL VARIABILITY IN THE WATER QUALITY OF HAND DUG WELLS IN MINNA AND ENVIRONS, NIGER STATE, NIGERIA

Abstract

Spatial-temporal variability in the water quality of hand-dug wells was investigated in Minna and Environs. Hand dug well water pollution is a major problem in the study area. Hence, the need to carry out groundwater quality assessment using spatial analyst tool in GIS in the study area becomes imperative. The Study analysed selected physicochemical and microbiological parameters of hand dug well water. Mixed methods approach of quantitative and qualitative research methods were adopted. A total of twenty four water samples were collected for both rainy and dry season from four locations and taken to the laboratory for the physicochemical (colour, odour, pH, Temperature, Turbidity, Conductivity, TDS, Cl– SO4, NO3, Acidity, Alkalinity, TH and TSS) and bacteriological (S. aureus, P. aeruginosa, E. coli, S. typhi) analysis in order to determine the level of pollutant concentration and the results were compared with NSDWQ and WHO standards. Standard laboratory testing methods were applied. Statistical analyses was conducted using one way ANOVA and Duncan PostHoc. WQI and Inverse Distance Weighted Technique in GIS were used for spatial distribution of Parameters. The results indicates that the physicochemical parameters analysed were within the NSDWQ and WHO recommended standards for both rainy and dry season except colour, odour Cl– and TH which exceeded the permissible standards. Just one sample and four samples during the rainy and dry season were recorded brown and slightly brownish respectively. Odour was detected in two samples only in the rainy season. The TH was significantly (p<0.05) highest in MK (626.67±174.58 mg/l) and MT (540.00±255.02) during dry season than the rainy season exceeding the NSDWQ (2007) and WHO (2011) limits of 500 mg/l respectively. While Cl– were significantly highest in MK (389.95±48.39 mg/l) and MR (291.88±49.35 mg/l) exceeding the permissible limit of 250 mg/l given by NSDWQ and WHO respectively. The result of microbiological parameters indicated that all the sample wells were significantly contaminated with the pathogenic bacteria and have exceeded the NSDWQ permissible limit of 0 cfu/ml. except that seasonal variation shows that S. aureus was not detected during dry season in MR and P. aeruginosa was not detected in CH and MT during rainy and dry seasons respectively. The results of WQI indicates that the physicochemical aspect of the water in the study area belongs the excellent and good water quality class during the rainy season while excellent, good and poor were recorded during the dry season. The study revealed that the physicochemical parameters of the well water samples of the study area are generally suitable for drinking and for domestic purposes while for the microbiological parameters shows that there is high contamination of pathogenic bacteria which is an indication of faecal contamination due to poor sanitation and hygiene. The hardness of the water should be soften for domestic purposes through the use of Soda and simple home white vinegar to neutralise excess calcium. The contaminated wells with pathogenic bacteria should be chlorinated with the help of a professional using at least unscented household liquid bleach of 1 gallon (3.79 litres) for a shallow or dug well of about 5.45 metres deep. Water contaminated with pathogenic bacteria should be boiled before use. The individual well owners should provide protective cover for the Wells and ensure proper hygiene and sanitation around the well water environment. Finally, treated water/boreholes should be made for all residence in Minna and environs.