Retention and volatilisation of kerosene: Laboratory experiments on glacial and post-glacial soils

Abstract

The influence of environmental conditions and soil characteristics on the retention and volatilisation of kerosene hydrocarbons in soils is investigated through laboratory experiments in six different glacial and post-glacial soils. The soils ranged between 0.55 and 1.80 g cm⁻³ in density, 29% and 70% in porosity, 0.4% and 28% in organic matter content, and 0% and 51% in clay content. The water retention capacity (WRC) could be estimated on basis of the bulk density and the sand, silt, clay and organic matter contents for many of the soils; for these soils a simple linear relation was identified between WRC and the kerosene retention capacity (KRC). Furthermore, the combined effects of soil porosity and soil moisture content on the KRC were found to be significant and could be quantified by a linear relationship. For moisture contents that can be expected in humid climate zones, the KRC will be relatively low and exhibit small variations between different soils. The effect of temperature on KRC was found to be small. The kerosene volatilisation flux was quantified as a function of time by a power law relationship, based on the initial surface density of kerosene in the soil and the prevailing temperature. The C₉–C₁₁ components of the kerosene had selectivities above zero and were thus removed preferentially, while the C₁₄ and C₁₅ components were characterised by negative selectivities. The selective volatilisation alters the composition of the kerosene that remains in the soil by increasing the concentration of the C₁₄ and C₁₅ components. The results for the different soil types indicate that the organic matter content of the soil affects the selective volatilisation, possibly through hydrophobic adsorption on surfaces, whereas the clay content appears to be less influential.