Distribution and potential ecological risk of heavy metals accumulated in subsidence lakes formed in the Huainan Coalfield, China

ABSTRACT

The potential environmental and ecological impacts caused by heavy metals are of great concern due to their toxicity and availability. Thirty-six sediment samples from subsidence lakes around three coal mines (with different exploration durations) were collected to evaluate the environmental and ecological impacts caused by coal mining activities. The concentrations of heavy metals (As, Cd, Cr, Cu, Pb, Zn, and Fe) were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Geo-accumulation and ecological risk assessment methods were employed to evaluate the potential environmental and ecological risks. The concentrations of As and Cd ranged from 13.5 to 47.4 and 0.26 to 1.75 mg/kg, respectively, which were much higher than the background values in Chinese soils (11.2 and 0.09 mg/kg, respectively). The highest average concentrations of heavy metals were detected in Xinzhuangzi Coal Mine, suggesting that possible emissions of heavy metals occurred during long-term coal mining processes (mining, transportation, coal combustion, and waste disposal). The geo-accumulation assessment indicated that the sediment in the vicinity of Xinzhuangzhi and Panyi Coal Mines was heavily contaminated by Cd. Based on the environmental and ecological risk assessment, As and Cd were regarded to be the priority control components. Appropriate countermeasures including the removal and utilization of coal rejects, application of a vegetative cover on coal rejects, and fixation of heavy metals and controlled disposal should be considered to eliminate environmental and ecological risks in coal mining areas.

KEYWORDS:

• Heavy metal
• distribution
• environmental impact
• coal mines

Acknowledgment

We acknowledge the editors and reviewers for polishing the language of the article and for in-depth discussion.

Funding

This work was financially supported by the Key Project of Natural Science Foundation, Department of Education in Anhui province (KJ2015A230), China Postdoctoral Science Foundation (2016M602037), the Key Research Project of Science and Technology of Huainan Government for 2016 (2016A13), the postdoctoral found project of Anhui Province (2016B103), and 2017 Colleges and Universities Outstanding Young Talents Support Program of Anhui province (gxyq2017061).