Changes in Heavy Metal Contents of a Waste Engine Oil Polluted Soil Exposed to Soil pH Adjustments
B. Ikhajiagbe *
Department of Plant Biology and Biotechnology, University of Benin, Nigeria
G. O. Anoliefo
Department of Plant Biology and Biotechnology, University of Benin, Nigeria
E. O. Oshomoh
Department of Plant Biology and Biotechnology, University of Benin, Nigeria
Nosakhare Airhienbuwa
Department of Plant Biology and Biotechnology, University of Benin, Nigeria
*Author to whom correspondence should be addressed.
Abstract
The present study investigated the role of soil pH adjustments in heavy metals concentrations in waste engine oil (WEO) - polluted soils. Sun-dried top soil (0-10cm) was measured into buckets. WEO was added to soil and mixed thoroughly to obtain similar concentrations of 2.5% w/w oil in soil. The polluted soil was thereafter amended with NPK (15:15:15) fertilizer to enhance microbial activity. The buckets were transferred into a well ventilated screen house with inherent constant room temperature (27ºC). The entire setup was divided into 5 sets. Each set was wetted daily with 200ml of different pH solutions (pH 3, 5, 7, 9, and 11) for a period of 3 months. There were significant reductions in heavy metal concentrations particularly at pH of 5. There were significant reductions in total hydrocarbons contents (THC) of polluted soils at 2 months after pollution from 1882.32 mg/kg at pH 3 to 325 mg/kg at pH 5, compared to THC of soil at 1 week after pollution at pH 7 (3425.63mg/kg).
Keywords: Contamination factor, environmental risk factor, hazard quotient, natural attenuation, pH, soil, waste engine oil