A re-assessment of metal pollution in the Dexing mining area in Jiangxi province, China: current status, hydro-geochemical controls, and effectiveness of remediation practices

Abstract

This study re-assess the environmental impacts of the Dexing copper mine (the largest open-pit copper mine in Asia) on the Lean river and its two tributaries (the Dawu river and Jishui river) in the Jiangxi province, China, with particular focus on metal pollution as well as the effectiveness and side-effects of remediation activities. Results show that the Dawu river and its mixing zone with the Lean river were still heavily influenced by acid mine drainage (AMD) and loaded with elevated levels of metals, in particular Mn, Ni, and Al whose concentrations were frequently above the health-based guideline values. Manganese and Ni in the AMD-impacted waters were predicted to occur as free ions or sulfate and carbonate complexes, and thus highly-toxic to living organisms. Although Al in the AMD-impacted waters was predicted to exist largely as colloidal hydroxides with low bioavailability, abundant formation of such nano-sized particles could impair the respiratory and circulatory systems of aquatic macro-invertebrates. The integration and comparison of the results from the current and previous studies show that the concentrations of several metals (Cu, Zn, and Cd) in the Dawu river decreased significantly after 2011–2012, during which several remediation practices were implemented (e.g., AMD neutralization, excavation of contaminated sediments in impounded rivers, and rehabilitation of mine tailings and open-pit slopes). This provides evidence that these remediation practices have effectively limited the dispersion of metals from the mining area. However, AMD neutralization greatly enhanced the release of sulfate, making the mining area an even more important sulfate source.

Spatiotemporal variation of vegetation cover in mining areas of Dexing City, China

“…Dexing City is a large mining city in China, located in Jiangxi Province (24°29'14" N to 30°04'41" N; 113°34'36" E to 118°28'58" E), China (as shown in Figure 1), whose proven reserves and developed minerals amount to more than 30 kinds, abounding in gold, silver, copper and other non-ferrous metals, including over 9 million tonnes of copper reserves [1] (Du et al, 2022). Dexing City is famous for its natural resource extraction and processing, with two large open-pit mines, the Yinshan Mine and the Dexing Copper Mine (as shown in Figure 1), as well as several non-ferrous metal extraction and processing enterprises [2,3] Since open-pit mining is a method of ore recovery by stripping the overlying rock and soil, the expansion of the pit will inevitably cause damage to the vegetation in the soil originally on the pit; at the same time, open-pit mining will have a large amount of solid waste discharge, so it is necessary to build tailing ponds to store mine solid waste, which will also occupy a large amount of land, thus causing damage to the vegetation in the soil originally on the land.…”

Investigation of Cu Adsorption and Migration with Spectral Induced Polarization in Activated Carbon

“…Heavy metal contamination is a vital environmental concern in most developing countries, causing soil and air pollution, disrupting ecosystems, and threatening human health. Copper, which is one of the most common heavy metals, is primarily derived from industrial wastewater [ 1 ], mineral processing [ 2 ], agricultural practices [ 3 ], and landfills [ 4 ]. Groundwater contaminated by Cu and other heavy metals can be contained and remediated using permeable reactive barriers (PRBs), which were used in several studies and led to satisfactory results [ 5 , 6 , 7 , 8 ].…”

Effects of Initial pH and Carbonate Rock Dosage on Bio-Oxidation and Secondary Iron Mineral Synthesis

“…An increase in coal mining activities in karst areas produces considerable amounts of AMD, which is characterized by low pH, high concentrations of iron (mostly Fe 2+ ), and other trace elements [ 21 ]. Considering the severe adverse effects of AMD on the fragile ecological environment of karst areas [ 22 , 23 ], the control and management of AMD have practical significance for the protection of ecological environments and sustainable development in karst watersheds. The AMD passive treatment technology was developed with cheap and easily available carbonate rocks as the reactive medium to effectively improve the pH of AMD, and it has had a good removal effect on Fe [ 24 ].…”