علوم آب و خاک (Feb 2021)
The Role of Earthworms (Eisenia fetida) on the Bioavailability of Contaminated Soil with Heavy Metals
Abstract
Earthworms are soil organisms commonly used in environmental studies and biological toxicology. Therefore, the present study aimed to investigate the role of Eisenia Fetida earthworms on the bioavailability of zinc and copper in the contaminated soils. This study was carried out on a contaminated soil sampled from the Ahangaran mine 26 kilometers far from the city of Malair and its surrounding areas. In this experiment, 12 earthworms with the average weight of 0.3 -0.6 g were selected for each soil sample. The worms were exposed to a metal contaminated soil for 42 days. After the test time, Zinc (Zn) and Cupper (Cu) concentrations were measured in different fractions of the soil. The results showed that cow manure, carrot pulp and vermicompost significantly reduced (at the level of 5%) 62.2, 80 and 65.2 mg / kg of the metal zinc concentration in carbonate, respectively, as compared to the treatment control. Earthworms significantly increased zinc (81.45 mg kg) in the carbonate fraction. On the other hand, there was a significant increase in the amount of exchangeable copper with the addition of organic fertilizer to worm, as compared to the control sample. This increase was significant (at the level of 1%) in the treatment of Vermicompost (1.27 mg / kg) and carrot pulp (1.32 mg / kg), as compared to control.
