Assessment of Bioavailability of Crude Oil in Three Different Agricultural Soils

Sorption ofcontaminants in soil and sequestration in soil particles is a process, the mechanisms of which are not well understood as yet. The aim of this study was to investigate sequestration and bioavailability of crude oil as a contaminant in three different soils. For this purpose, three different soil samples with different textures (loamy sand, loam, and clay loam) but with the same organic carbon were collected. After sterilization, the soils were spiked with crude oil. Each soil sample was contaminated as aged and fresh, and inoculated with a consortium ofthree bacterial isolates. Respiration was analyzed on days 0, 30, 60, and 90 after inoculation. Bacterial population was also assessed at the beginning and at the end ofthe bioremediation and residual contaminant at the end ofthe bioremediation process. The results showed that in soils with the same organic carbon, texture is an important parameter in aging and sequestration of the contaminant. In addition, it was observed that the best degradation was accomplished in the loam soil, due to more bioavailability as compared to the clay loam soil and less inhibitory effect of the contaminant on microbial growth, resulting from lower bioavailability, as compared to the loamy sand soil.