Investigation of physical and chemical characteristics on soil due to crude oil contamination and its remediation

Abstract

Oil contamination causes serious geoenvironmental concern and adversely affects the soil environment due to the release of toxic by-products. Hence, the aim of the study was to investigate the influence of oil contamination on soil physical and chemical properties and phytoremediation as a treatment option based on field studies conducted for analyzing significant parameters. The sites selected were near National Institute of Technology, Surathkal, Karnataka (site-1), and another is close to the oil refinery (Kuthethur, Karnataka, India, as site-2). Phytoremediation of oil-contaminated samples was carried out by Chromolaena odorata. The evaluation of soil physical and chemical properties includes field and laboratory tests. A pumping test was conducted to estimate aquifer parameters in the field. The hydraulic conductivity for field soil sample (unsaturated condition) is carried out by a filter paper test. Laboratory tests to evaluate physical and chemical parameters include total petroleum hydrocarbons of contaminated (crude oil varying from 0 to 10% at an interval of 2%) and uncontaminated samples and plant parameters. Characterization of contaminated and uncontaminated soil sample was performed by Fourier transform infrared (FTIR) spectroscopy. The results obtained reveal that physical properties of soil (moisture content, liquid and plastic limit) got affected due to oil contamination. Relative hydraulic conductivity was established as 0.46 (uncontaminated) and 0.57 (contaminated) for soil samples and led to the conclusion that hydraulic conductivity was drop down by 10% due to oil contamination. Total petroleum hydrocarbon analysis reveals that the uptake/presence of hydrocarbons by showing increased concentration in contaminated soils (5% and 10%) by the plant species. This is further confirmed by FTIR results. The TPH concentrations in the contaminated soils were reduced up to 50-60% and also showed better plant growth after 7weeks of transplantation. Hence, considered plant species possess high potential for degrading oil contaminated in the soil.