Micromorphological Characteristics of Polluted Soils in Tehran Petroleum Refinery

In this study, micromorphological properties of some samples collected from pedons polluted with petroleum refinery wastes and some adjacent unpolluted pedons were studied. After description of the studied pedons, disturbed and undisturbed samples were collected for physicochemical and micromorphological analyses. The results showed that the physicochemical properties (i.e. structure, bulk density, pH, EC and organic matter) of the soils polluted with petroleum wastes were strongly changed. Prolonged exposure of soils to the petroleum wastes resulted in the formation of specific and distinctive micromorphological features. Strongly developed granular microstructure and infillings of solid petroleum wastes alone or mixed with soil aggregates were some of the most important pedofeatures which were observed in deeper horizons. The existence of excrement belonging to different soil micro and macro fauna, coatings, hypocoatings, quasicoatings, and zones depleted from petroleum dissolvable materials at different depths were the other features throughout the pedons. The type of developed pedofeatures was correlated with the state of petroleum wastes and their fluidity in penetration, deposition, or dissolving and removal of soil compounds. This study demonstrated that micromorphology can be used as a powerful technique in characterization of petroleum polluted soils.