Behaviour of fuel organic compounds in contaminated soils and development of a phytoremediation procedure

Abstract

Soil contamination with fuel derived organic compounds is a problem principally caused by emissions and residues from the petrochemical industry, traffic accidents, and accidental leaks in pipelines or in underground fuel storage tanks. Soils contaminated with fuels have a high environmental risk, since they can contaminate other environmental compartments, with the inherent risks for human health and for the environment. Sorption to soil particles, volatilization, leaching, degradation (chemical, photochemical and biological oxidation), plant translocation, etc., are the principal processes that will influence on the final fate of soil contaminants in the environment. In order to interpret, evaluate the risks and make decisions about the effects of fuel compounds and assure and adequate protection of the environment, it is very important to understand the toxicology, analytics and the behaviour and fate in the environment. Within this context, the present doctoral thesis has the following objectives: Development of analytical methods for volatile compounds (MTBE, ETBE and BTEX) and diesel range organics (DRO) in soil and water. Application of those methods to the characterization of a site contaminated with hydrocarbons. Study of the dynamics of petroleum contaminants in the soil-plant-water-air system through sorption and leaching experiments and a experiment with root exudates, to study the effect of plants on contaminant mobility through soils. Characterization of gasoline and diesel phytotoxicity, with crop plants bioassays. At last, application of a phytoremediation procedure with Lupinus luteus growing on the A and B horizons of a Cambisol contaminated with diesel (1%, w/w), with the inoculation of best plant growth promoting and degrader bacteria, with the best results from previous experiment. The experiments carried out in this thesis, allowed to obtain a wide knowledge of the behaviour of those contaminants in the soil system, and to predict their final fate in the environment, in addition to their toxic effect once released in soil. The proposed remediation techniques, through bacteria assisted phytoremediation, resulted in a clean, cheap, reliable and highly efficient technique, what predicts satisfactory results in its application to real soils.