Effect of iron slag, zeolite, and Piriformospora indica fungus on mazut biodegradation in a heavy metal-polluted soil that was amended with cow manure under canola cultivation

Petroleum hydrocarbon pollution in the soil is one of the important problems in environmental studies. Thus, this research was conducted to evaluate the effect of iron slag, zeolite, and Piriformospora indica fungus on mazut biodegradation in a heavy metal‑polluted soil that was amended with cow manure under canola cultivation.

Treatments included application of zeolite (0% and 2% [W/W]) and iron slag enriched cow manure (0, 15, and 30 t/ha) in a mazut‑polluted soil (0%, 4%, and 8% [W/W]) under canola cultivation in the presence of P. indica. After 70 days, plants were harvested and the mazut biodegradation in the soil was measured. In addition, the soil and plant Pb and Cd concentration was measured using atomic absorption spectroscopy.

Soil application of zeolite (2% [W/W]) in the mazut‑polluted soil (4% [W/W]) significantly increased the mazut biodegradation in the soil by 13.1%. In addition, plant inoculation with P. indica significantly increased the mazut biodegradation in the soil and decreased the plant Pb and Cd concentration. Soil application of cow manure at the rate of 15 and 30 t/ha has also increased the mazut biodegradation in the soil by 14.1% and 17.4%, respectively.

Using iron slag enriched cow manure and zeolite had additive effects of increasing the mazut biodegradation in the soil and decreasing the soil and plant heavy metal concentration. However, these changes depend on the plant physiology and soil physic‑chemical properties that should be considered in different studies.