Study on Heavy Metal Contamination in High Water Table Coal Mining Subsidence Ponds That Use Different Resource Reutilization Methods

Min Tan,Kun Wang,Junfeng Qu,Zhou Xu,Hanghe Li

doi:10.3390/w12123348

Abstract

Heavy metals accumulate in high water table coal mining subsidence ponds, resulting in heavy metal enrichment and destruction of the ecological environment. In this study, subsidence ponds with different resource reutilization methods were used as study subjects, and non-remediated subsidence ponds were collectively used as the control region to analyze the heavy metal distributions in water bodies, sediment, and vegetation. The results revealed the arsenic content in the water bodies slightly exceeded Class III of China’s Environmental Quality Standards for Surface Water. The lead content in water inlet vegetation of the control region and the Anguo wetland severely exceeded limits. Pearson’s correlation, PCA, and HCA analysis results indicated that the heavy metals at the study site could be divided into two categories: Category 1 is the most prevalent in aquaculture pond B and mainly originate from aquaculture. Category 2 predominates in control region D and mainly originates from atmospheric deposition, coal mining, and leaching. In general, the degree of heavy metal contamination in the Anguo wetland, aquaculture pond, and fishery–solar hybrid project regions is lower than that in the control region. Therefore, these models should be considered during resource reutilization of subsidence ponds based on the actual conditions.

Highlights

Since the groundwater level in regions with a high water table is high, a large subsidence pond will form after a coal mine has collapsed [1]
There is an urgent need to carry out resource reutilization of coal mining subsidence ponds
River contains recycled water that was obtained after treatment of wastewater from the Longgu non-remediated subsidence pond, which were collectively used as the control region

Summary

Introduction

Since the groundwater level in regions with a high water table is high, a large subsidence pond will form after a coal mine has collapsed [1]. This drastically decreases the land area and affects the ecological structure to some extent and disrupts the ecological equilibrium. Subsidence ponds are usually closed or semi-closed systems to which atmospheric deposition and mine water will carry pollutants from the surroundings, resulting in the accumulation of high levels of heavy metals in these water bodies. Irrigation with contaminated water on surrounding farms, along with excessive chemical fertilizer application, further exacerbate heavy metal contamination in water bodies. There is an urgent need to carry out resource reutilization of coal mining subsidence ponds

Methods

Results

Conclusion