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Chinese Journal of Ecology ›› 2022, Vol. 41 ›› Issue (1): 124-131.doi: 10.13292/j.1000-4890.202201.005

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Effects of earthworm on bioavailability of heavy metals in reclaimed soils with different thickness.

LU Fu-qing1, WANG Xing-ming1,2,3,4*, CHU Zhao-xia6, WANG Yun-min2, FAN Ting-yu1,4, DONG Zhong-bing1, XU Xiao-ping5, BAI Xin1   

  1. (1School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, Anhui, China; 2State Key Laboratory of Safety and Heafth for Metal Mines, Sinosteel Maanshan General Institute of Mining Research Company Limited, Maanshan 243071, Anhui, China; 3Collaborative Innovation Center of Recovery and Reconstruction of Degraded Ecosystem in Wanjiang Basin Co-founded by Anhui Province and Ministry of Education, Anhui Normal University, Wuhu 241000, Anhui, China; 4Engineering Laboratory of Comprehensive Utilization and Ecological Protection of Soil and Water Resources in High Diving Level Mining Area of Anhui Province, Huainan 232001, Anhui, China; 5College of Architecture and Urban Planning, Anhui Jianzhu University, Wuhu 241000, Anhui, China; 6School of Biological Engineering, Huainan Normal University, Huainan 232038, Anhui, China).
  • Online:2022-01-10 Published:2022-06-10

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Abstract: The physicochemical properties and heavy metal level of the reclaimed soil filled with topsoil on coal gangue can significantly affect the subsequent ecological utilization. The purpose of this study was to explore the effects of earthworm on the total amount and available state of heavy metals (Cr, Cu, Pb, and Zn) in reclaimed soil with different topsoil thickness on gangue. Five thicknesses (10, 20, 30, 50, and 70 cm) were adopted for soil column experiment. Earthworms were inoculated into reclaimed soil to investigate the ecological function of earthworms on the reclaimed soil. We measured pH, organic matter (OM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), and heavy metals (Cr, Cu, Pb and Zn) contents in reclaimed soil. Within the overlying thickness of 10-70 cm, earthworm inoculation significantly reduced the pH of reclaimed soil to neutral. Compared with the control, soil OM was increased by 7.0%-13.5%, soil TN was increased by 7.5%-13.4%, TP was increased by less than 6.0%, and TK was increased by less than 2.0%. Therefore, earthworm had a good ecological improvement effect on OM and TN of the reclaimed soil. Furthermore, earthworm inoculation reduced the total amount of heavy metals and the contents of available heavy metals in reclaimed soil. The synergistic effect of earthworm and soil thickness significantly reduced the contents of total Pb and available Zn in the reclaimed soil. After inoculation of earthworms, the concentrations of total Cr, Pb and Zn, available Cr and Pb in reclaimed soil were mainly affected by TP, while the concentrations of total Cu and available Cu and Zn were mainly affected by TN. Thus, the behavior of heavy metals in reclaimed soil under earthworm inoculation was mainly influenced by TP and TN. As a result, inoculation of earthworm can improve the physical and chemical properties of reclaimed soil and reduce the concentration of heavy metals in reclaimed soil, thus producing positive ecological effects. Our results provide new ideas and methods for the reclamation of coal gangues.

Key words: earthworm, reclamation soil, coal gangue, ecological improvement.