Control of Contaminant Transport Caused by Open-Air Heavy Metal Slag in Zhehai, Southwest China

Jiang Zhao, Zhihua Chen, Tao Wang, Caijuan Xiang, Mingming Luo and Hongxin Yuan
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Jiang Zhao: School of Environmental Studies, China University of Geosciences, 388 Lumo Rd, Wuhan 430074, China
Zhihua Chen: School of Environmental Studies, China University of Geosciences, 388 Lumo Rd, Wuhan 430074, China
Tao Wang: School of Environmental Studies, China University of Geosciences, 388 Lumo Rd, Wuhan 430074, China
Caijuan Xiang: School of Environmental Studies, China University of Geosciences, 388 Lumo Rd, Wuhan 430074, China
Mingming Luo: School of Environmental Studies, China University of Geosciences, 388 Lumo Rd, Wuhan 430074, China
Hongxin Yuan: Yunan Chihong Zinc and Germanium Co., Ltd. Huize Branch, Huize 654212, China

IJERPH, 2019, vol. 16, issue 3, 1-21

Abstract: Slag heaps are formed by mining waste materials, and the improper treatment of leachate from such heaps can threaten nearby aquifers. The Zhehai slag heap in Yunnan Province, China, contains 2.7 million tons of zinc and cadmium slag, and is considered a heavy metal source threatening the local groundwater safety, however, the severity of contamination remains unknown. In this study, numerical modeling was used to predict the groundwater flow and contaminant transport in this area based on field data. The results show that the atmospheric precipitation infiltration recharge at the top of the heap is 81.8 m 3 /d, accounting for 93.76% of total infiltration. The south and east sides of the area are the main outflow channels for contaminants, accounting for 93.25% of the total discharge around the heap. To reduce aquifer contamination, an in situ system involving a “controlling the source, ‘breaking’ the path, and intercepting the flow” (CSBPIF) strategy is established. The results indicate that the system performs well because it not only decreases the flow velocity but also reduces the concentrations of contaminants adsorbed by clay media. Moreover, the equivalent bottom liner thicknesses of the clay layers were calculated to improve the applicability of the CSBPIF system. Compared with ex situ disposal, this scheme provides an economic and effective solution and can be used to prevent and control groundwater pollution in China.

Keywords: open-air heavy metal; groundwater modeling; reactive transport; in situ treatment (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2019
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