Characterization of Environmental Samples around an Indigenous Refinery in Nigeria

Useh Mercy Uwem

doi:10.11648/j.bmb.20170206.12

Abstract

Co-contamination by petrochemicals and heavy metals emanating from refinery operations was investigated from sludge, soil and water samples immediately around WRPC refinery, Delta State, Nigeria. Collection and assessment of environmental samples from 5 different points across the refinery and groundwater for which the pH, Electrical Conductivity, Temperature, Turbidity, TDS, TSS, Total hardness, Alkalinity, DO, BOD, Clˉ, PO43ˉ and bacteriological analysis were measured. The total petroleum hydrocarbon and polycyclic aromatic hydrocarbon concentrations were 755.291 and 22.746 mg L-1 in the water samples, 8756.148 and 311.569 mg kg-1 for the soil samples, 65346.8 and 4190.598 mg kg-1 for the sludge samples via GC-MS analysis. The effects of the release of the industrial effluents caused the increase in pH, 5.2-5.3 across the studied samples. Conductivity measurements for the sludge, soil and water samples gave readings of 0.27, 0.25 and 0.48 µs cm-1 respectively. The presence and distribution of different heavy metals varied whereby the presence of cadmium (0.139 mg/l), cobalt (0.34 mg/l) and nickel (0.606 mg/l) in the water samples were above the WHO permissible limits. The highest concentrations of iron (108.77 mg/kg) and zinc (11.072 mg/kg) where observed in the soil samples while chromium (24.25 mg/kg), lead (3.902 mg/kg), mercury (0.21 mg/kg), arsenic (0.417 mg/kg), copper (2.015 mg/kg) and manganese (82.695 mg/kg) where highest in the sludge samples. Total bacterial enumeration revealed a count of 7.29 x 103 (cfu/g), 1.84 x 103 (cfu/g) and 1.32 x 103 (cfu/ml) in the soil, sludge and water samples respectively. The presence and concentrations of these mixed pollutants via the activities of the refinery resulted in change of known physicochemical properties which in turn affects the vegetative and microbial flora within the area.

Highlights

The persistent use of petroleum and the increased demand for its by-products for numerous applications places a huge constraint on the immediate environment [1,2]
The total petroleum hydrocarbon (TPH) and polyaromatic hydrocarbon (PAH) concentrations in the sludge, soil and water were detected in each sample at 65,346.8, 4,190.6 in the sludge, 8,756.1, 311.6 in the soil and 755.3, 22.7 for the water samples respectively (Table 1)
Run-offs from the refinery would account for the increased in pH observed in the sludge samples as the source of the concentrated pollutants whereby via the natural process of leaching, these contaminants leach out into the waterways resulting in the increased pH of the water samples

Summary

Introduction

The persistent use of petroleum and the increased demand for its by-products for numerous applications places a huge constraint on the immediate environment [1,2]. Operational activities around petroleum refineries like several in the Niger Delta region of Nigeria are renowned for its cumulative oil spills due to large oil deposits [3,4,5]. These sites are poorly and most often never investigated to know the extent of petroleum hydrocarbon contamination and as a result there is high possibility of accumulation of these pollutants in the food chain by their consumption in drinking water, fish and crops, which could pose a risk to human and other terrestrial and aquatic life [6,7,8].

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Results

Conclusion