Magnitude of faecal contamination of rural community well waters in Nigeria and its relationship to well and water properties.
The possible relationship between high numbers of fecal coliforms (FCs), fecal streptococci (FS), standard plate count (SPCs) and well characteristics viz: well depth, water column, temperature, pH and non-filterable residue in 25 rural community wells in the Port Harcourt region, Nigeria, was studied. Zonal differences in residue level, well depth and fecal indicator bacteria were observed; these parameters were lowest in an area of high population density (slum) reclaimed from and adjacent to mangrove forests. Although some wells were covered and/or walled to protect them from surface runoff contamination, FCs and FS were recovered from all, except three, in numbers (log10 per 100 mL) ranging respectively from 0.40-3.79 and 0.70-3.44. The FC:FS ratio was less than 1.0 in 8 and greater than 1.0 in 14 samples. Well depth correlated with FCs (p = 0.01; r = 0.5684), FS (p = 0.001; r = 0.6423), pH (p = 0.0001; r = 0.5981); FCs and FS correlated significantly (p = 0.01; r = 0.4948). SPCs did not correlate significantly with FCs, FS and the well and water characteristics. Simultaneous analysis of samples by the Membrane-filtration (MF) and Most Probable Number (MPN) methods recovered mean FC counts in the decreasing sequence: Standard-MPN----Anaerobic----Aerobic MF----Direct-MPN. The underground water table is most probably contaminated via large numbers of soakaway pits and similar conveniences. Downward movement of contaminant from the shallow conveniences into deeper water tables may explain the well depth: indicator bacteria correlation.
Ogan
M T
MT
Department of Microbiology, Faculty of Science, University of Port Harcourt, Rivers State, Nigeria.
D000704:Analysis of Variance; D001419:Bacteria / Q000254:growth & development*; D015169:Colony Count, Microbial; D004755:Enterobacteriaceae / Q000254:growth & development; D005243:Feces / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D009549:Nigeria; D012424:Rural Population; D013291:Streptococcus / Q000254:growth & development; D013696:Temperature; D014871:Water Microbiology; D014876:Water Pollution; D014881:Water Supply