Asian Journal of Microbiology, Biotechnology & Environmental Sciences Paper

Vol 15 Issue 1, 2013; Page No.(13-18)

SEASONAL DYNAMICS OF SOME ORGANIC CONTAMINANTS IN GROUNDWATER IN SOME PARTS OF THE NIGER DELTA, NIGERIA

G.C. OKPOKWASILI AND S.I. DOUGLAS

Abstract

The organic quality of some groundwater samples collected around ten flowstations in Niger Delta Nigeria were investigated to demonstrate the effects of oil activities on the organic levels of the water samples. Groundwater samples were collected monthly from the flowstations for twenty four months. Standard analytical techniques as specified by the Department of Petroleum Resources (DPR) and American Public Health Association (APHA) were adopted to analyse the samples. The results revealed that the conductivity values were higher in dry season than the rainy season for all samples analysed and the values ranged from 38.22-241.76μS/cm. The temperature at the various locations ranged from 24 to 27.9 0C with the dry season showing higher values than the rainy season. The values for temperature were not significantly different at P < 0.05 while that for conductivity was significant at P<0.05. Higher dissolved oxygen values were also observed for the rainy than dry season, which ranged from 1.98 to 6.23mg/L. BOD values for the rainy season were higher than the dry season values, the values were 0.35-6.29mg/L which was above the permissible limits for domestic water acceptability. TPH values were in the range 0-445mg/L, this shows the level of pollution in that area and the great damage done to groundwater. Total heterotrophic bacteria (THB) counts had mean values of 4.6 x 103 CFU/mL and 5.2 x 102 ± 0.024 CFU/mL for wet and dry seasons respectively, while total fungi (TF) counts had values of 8.2 x 102 ± 0.029 CFU/mL for rainy season and 4.2 x 101 ± 0.02 CFU/lm for dry season. The mean value for hydrocarbon utilizing bacteria (HUB) was 3.5 x 103 ± 0.027 CFU/mL and 2.5 x 101 ±0.02 CFU/mL for dry and rainy seasons respectively and mean values for hydrocarbon utilizing fungi (HUF) were 3.0 x 102 ±0.025 CFU/mL for rainy season and 3.0 x 101 ±0.2 CFU/mL for the dry season. Apart from in one location for the months of June, July and August, total coliform bacteria were not observed in all other locations sampled. Salmonella and Shigella were not isolated in all the samples analysed, showing minimal contamination. Generally, higher microbial loads were observed in rainy season, than dry season which were in this order; THBC>HUB>TFC>HUF. The results indicate seasonal changes in the parameters that were studied as well as influence of operational and storage activities in crude oil facilities, on the organic load of the water samples analysed.

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