CHEMICAL APPROACHES TO MONITORING AND EVALUATING THE BIOREMEDIATION OF OIL CONTAMINATED DESERT SOILS: A REVIEW OF MODERN METHODS

Abstract

Oil spills in deserts and other arid regions, including Kuwait, the Arava Valley in Israel, and Western Kazakhstan, have created extensive areas of chronically contaminated soil whose remediation is constrained by low moisture, nutrient deficiency, salinity, temperature fluctuations, and the ageing of petroleum residues. The purpose of this review is to systematise modern chemical and physicochemical approaches to monitoring and evaluating the bioremediation of oil-contaminated desert soils and to identify indicators suitable for an integrated, risk-based assessment. The review considers the composition of crude oil as a multicomponent contaminant, including total petroleum hydrocarbons, polycyclic aromatic hydrocarbons, BTEX compounds, resins, and asphaltenes, as well as the soil properties that control their mobility, bioavailability, persistence, and toxicity. Natural attenuation, biostimulation, bioaugmentation, biopiling, and phytoremediation are compared with chemically enhanced treatments based on Fenton and persulfate oxidation, nanomaterials, electrokinetic processes, microwave heating, and bioelectrochemical systems. Particular attention is paid to combining chromatographic and spectroscopic determination of petroleum fractions with soil respiration, microbial and functional-gene indicators, ecotoxicological tests, and remote-sensing observations. Hyperspectral data and artificial-intelligence methods are discussed as tools for mapping contamination and tracking spatial changes during remediation. Sorbent materials, including shungite-based compositions relevant to Kazakhstan, are considered for the preliminary containment and removal of oil. The analysis shows that a decrease in total petroleum hydrocarbons alone is insufficient to demonstrate environmental recovery because persistent aromatic fractions and residual toxicity may remain.