Sulfate migration in a river affected by acid mine drainage from the Dabaoshan mining area, South China. (January 2015)

• Record Type: Journal Article
• Authors: Chen, Meiqin; Lu, Guining; Guo, Chuling; Yang, Chengfang; Wu, Jingxiong; Huang, Weilin; Yee, Nathan; Dang, Zhi
• Is Part Of: Chemosphere. Volume 119(2015)
• Page Start: 734
• Page End: 743
• Publication Date: 2015-01
• Subjects: Mining area -- SO42- migration -- AMD-affected river -- Iron oxyhydroxide; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2014.07.094
• Languages: English
• ISSNs: 0045-6535

Abstract

Graphical abstract: Highlights: River physicochemical characteristics for SO 4 2 - migration were investigated. Sulfur distributions provided evidences for SO 4 2 - shifting in river. Geochemical calculations were used to predict SO 4 2 - precipitation behaviors. Mineralogical characteristics were used to indicate SO 4 2 - patterns in sediments. The central role of SO 4 2 - behavior on the migration of heavy metals was discussed. Abstract: Sulfate, a major component of acid mine drainage (AMD), its migration in an AMD-affected river which located at the Dabaoshan mine area of South China was investigated to pursue the remediation strategy. The existing factors of relatively low pH values of 2.8–3.9, high concentrations of SO 4 2 - (∼1940 mg L −1 ) and Fe 3+ (∼112 mg L −1 ) facilitated the precipitation of schwertmannite (Fe8 O8 (OH)6 SO4 · n H2 O) in the upstream river. Geochemical model calculations implied the river waters were supersaturated, creating the potential for precipitation of iron oxyhydroxides. These minerals evolved from schwertmannite to goethite with the increasing pH from 2.8 to 5.8 along the river. The concentration of heavy metals in river waters was great reduced as a result of precipitation effects. The large size of the exchangeable sulfate pool suggested that the sediments had a strong capacity to bind SO 4 2 - . The XRD results indicated that schwertmannite was the predominant form of sulfate-bearing mineral phases, which was likely to act as a major sulfate sink by incorporating water-borne sulfate into its internal structure and adsorbing it onto its surface. The small size of reduced sulfur pools and strong oxidative status in the surface sediments further showed that SO 4 2 - shifting from water to sediment in form of sulfate reduction was not activated. In short, precipitation of sulfate-rich iron oxyhydroxides and subsequent SO 4 2 - adsorption on these minerals as well as water dilution contributed to the attenuation of SO 4 2 - along the river waters.