The Role of Earthworms in Heavy Metal Remediation of Selected Soil in Baghdad Governorate/Iraq

Year 2025, Volume: 10 Issue: 2, 510 - 523, 01.09.2025

Ulla Reyadh , Kamal B. Al-paruany Maysoon H. Mashjel

https://doi.org/10.28978/nesciences.1744885

Abstract

This study examined the earthworms' role in removing heavy metals and their impact on soil degradation in some regions of Baghdad City/Iraq. Six sites named agricultural (S1), Plastic factory (S2), Oil factory (S3), Barren (S4), Residential soil (S5), and landfill soil (S6), between February and June 2024 were collected, In the dry period, the total concentration of Pb, Cu, Zn, Mn, Cd, and Fe heavy metals in the soil samples range from 3.13 to 26.4mg kg-1, 4.2 to 33.6mg kg-1, 15.9 to 114mg kg-1, 319 to 715mg kg-1, 0.81 to 5.19mg kg-1, and 603 to 5142 mg kg-1; in the wet period, it ranges from 3.07 to 24.7mg kg-1, 13.3 to 31.13mg kg-1, 23.17 to 106.9mg kg-1, 299.2 to 690mg kg-1, 0.35 to 2.05mg kg-1 and 565 to 4822 mg kg-1. The results show that the conditions of 50 earthworms and 28 days, had the best reduction rate in the concentrations of heavy elements (cadmium and copper) in the three contaminated soils (S3, S5, and S6). The worms' high ability and maturity during the 28 days before their death were the causes of these rates and the treatment was affected by contamination level, soil moisture, and Aeration. At the 5% probability level, the results revealed a negative and significant correlation, with an efficiency (R2 x 100) ranging from 67 to 99.0. The regression analysis's findings also demonstrated that employing a large number of earthworms (50) reduced the cadmium concentration in the three polluted soils by -0.044, -0.057, and -0.0929 units per day of treatment, respectively, with use efficiencies of 89.9%, 67.0%, and 99%. the copper content in the polluted soils (S6, S5, S3) decreased by -0.0444, -0.227, and -0.141 one unit per unit. With a usage efficiency of 89.9, 91.1, and 84.3.

Keywords

Baghdad , Earthworms , Biodegradation , Heavy metals , Cadmium and Copper

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