Effect of Soil Type on the Fate of Kerosene Compounds in the Presence of Water and Ethanol

Abstract

The effect of soil type on the fate of kerosene compounds in the presence of water and ethanol was studied. Mini lysimeter experiments were conducted to compare the transport and sorption of kerosene compounds in different soil types, namely sand, silt and clay. The soils were artificially contaminated with 7% (w/w) kerosene in the absence and presence of ethanol. Rainfall simulation was performed until zero concentration of kerosene compounds was observed in the effluent. The results obtained showed significant variations in the transport and sorption of kerosene compounds in the different soil types. Benzene (11.9, 8.9, and 5.5 mg/l), toluene (10.9, 8.6 and 6.3 mg/l) and xylene (12.8, 8.5 and 5.8 mg/l) were leached in sand, silt, and clay, respectively. Conversely, benzene (3.0, 5.3, and 7.8 mg/kg), toluene (4.0, 5.5 and 9.6 mg/kg) and xylene (4.7, 6.4 and 9.1 mg/kg) were retained in sand, silt and clay, respectively. Generally, the transport of the kerosene compounds in the different soil types was in the order of sand>silt>clay, while the retention was in the order of clay>silt>sand. The sorption coefficient (K d ) and retardation factor (R) were found to be in the order of xylene>toluene>benzene for the kerosene compounds, and in the order of clay>silt>sand for the soil types. The presence of ethanol enhanced the transport of the kerosene compounds but reduced their sorption, K d and R, to varying percentages, ranging from 12 to 76%. These effects were generally greatest in sand except in the case of R where it was in clay, and generally affected xylene more than the other aromatic kerosene compounds.