Determination of the effect of pollution on the total microbial load and diversity in the surface and groundwater in selected pollution-prone towns in Cross River State, Nigeria

Groundwater is an important natural resource that majority of the human population depends on for drinking. Potable water is essential for good health and the socio-economic development of man. This research aimed at evaluating the effect of pollution on the total bacterial load and biochemical characteristics of bacteria isolates associated with surface and groundwater samples closed to dumpsites and abattoirs in six Local Government Areas (LGAs) in Cross River State. Borehole water samples were subjected to standard laboratory procedures, and microbiological examination of the borehole water samples was carried out. Pour plate technique was used for plating the samples, 1ml of the sample was transferred into Petri dishes (in triplicate), containing potato dextrose agar (PDA) for fungal enumeration, and nutrient agar (NA) for bacterial enumeration. An aliquot of each sample was transferred into the plate for each sample, thoroughly mixed and allowed to solidify, then incubated at room temperature for 24 hours (for NA) and 72 hours (for PDA). After incubation, the colonies were observed, counted and recorded. Identification of pure cultures was done by studying colony characteristics, and biochemical characteristics. The results revealed that the bacterial population was high in the groundwater samples obtained from Calabar municipality (slaughter house), Ogoja (dumpsite) was next and significantly higher in the bacteria counts than samples obtained from Akamkpa (dumpsite), Calabar municipality (control, dumpsite), Ikom (dumpsite, slaughter house), Ogoja (slaughter house) and Yala (dumpsite and slaughter house) with no significant difference (P>0.05) in the mean bacterial counts. The lowest bacterial count was detected in the groundwater samples from Akamkpa (slaughter house), Ikom, Yala and Ogoja (control), and Yakurr (control, slaughter house, dumpsite) with no significant difference (P>0.05) in the bacteria counts obtained. It was evident from the results, that there was a high level of contamination of groundwater sources within the areas visited, and this calls for urgent health intervention.