Impact of crude oil water soluble fraction on soil physiochemical properties and bacteria

Abstract

Owing to the underlying negative impact of crude oil to the ecosystem, this study investigated the effect of water soluble fraction (WSF) of crude oil on selected soil physiochemical properties and bacteria using appropriate standard methods. The investigation was carried out using control (without WSF), 2, 5, 10 and 20% concentration for 42 days and analysis was carried out at day 0, 14, 28 and 42 using standard protocol. The result showed that WSF treatment increased the concentration of physicochemical properties especially for day 0 while as the time of exposure increased their concentration decreased. A significant (p<0.05) increase in THC, nitrate, electrical conductivity and sodium ion at day 0 across from control to 20% and a similar result at day 14 for nitrate, however as concentration increased with time a significant decrease was observed except for sodium which had little or no changes. pH decrease with time from day 0 to day 14 and maintained a steady concentration afterwards. Potassium, calcium and magnesium ion conc. decreased significantly (p<0.05) for each time (Day 0, 14, 28 and 42). Bacteria count decreased as exposure time increased, and increased with concentration within specific time. Bacteria count significantly decreased at day 0, increased significantly at WSF 20% for day 14 and 28 while an insignificant decrease was observed at day 42 when compared with control. This result suggests that consistent contamination with WSF could adversely alter the soil physiochemical properties and decrease soil bacteria count leaving just hydrocarbon degrading bacteria such as Pseudomonas spp. and Bacillus subtilis to thrive. Oil spillage site should be prevented or promptly remediated to maintain soil physicochemical properties and indigenous microbes essential for soil fertility and Nutrient availability to plants.

Keywords: Water soluble fraction, Oil spillage, Soil Physiochemical properties, Soil Bacteria