Ecological basis of the restoration and reclamation of oil-contaminated soils in the Naftalan area of Azerbaijan

Abstract

Oil contamination is an important driver of soil degradation in Azerbaijan and is not limited to the Absheron Peninsula. This study evaluates the ecological conditions that constrain the natural recovery of oil-contaminated soils in the Naftalan area of western Azerbaijan and develops site-specific reclamation priorities from field observations, route-based surveys, spatial inspection, and comparative analysis. Field investigations initiated in 2024 documented contaminated patches, oil pools, vegetation responses, and areas surrounding former oil wells. The study indicates that arid conditions, strong insolation, high summer soil-surface temperatures of up to 45–50 °C, low soil moisture, and sparse vegetation reduce microbial activity and limit natural self-purification. Contamination severity was classified into four levels—low, moderate, high, and very high—and linked to progressively stronger restoration measures ranging from soil loosening and biostimulation to technical removal, bioremediation, sorption, and phytoremediation. The choice of reclamation technology should additionally account for oil composition, contamination duration, soil physicochemical and hydrophysical properties, terrain, climate, and vegetation. Tolerant herbaceous species identified as suitable candidates for biological reclamation include Anabasis aphylla, Artemisia maritima, Petrosimonia brachiata, Sorghum spp., Phragmites australis, Cynodon dactylon, and Alhagi maurorum. The findings support a staged, site-specific reclamation framework for reducing environmental risks and returning degraded land to appropriate recreational, agricultural, afforestation, or other uses.