Effects of mining activities on evolution of water chemistry in coal-bearing aquifers in karst region of Midwestern Guizhou, China: evidences from δ13C of dissolved inorganic carbon and δ34S of sulfate

Abstract

The generation of acid mine drainage (AMD) may accelerate watershed erosion and promote the migration of heavy metals, then threaten local ecosystems such as aquatic life and even human health. Previous studies have focused primarily on influence of AMD in surface environment. In order to reveal the acidizing processes in karst high-sulfur coalfield in Southwest China, this study, by contrast, focused on the hydrogeochemical evolution process and acidification mechanism of mine water in Zhijin coalfield, western Guizhou Province. The oxidation of pyrite and other sulfides induced strong acidification of mine water according to the water chemical analysis. As a result, a series of geochemical processes such as dissolution of carbonates and silicates, hydrolysis of metal ions, and degassing of CO complicated water chemical evolution. The dissolution of silicates controlled the chemical composition of mine water, but more carbonates might be dissolved during the acidification of mine water. The sources of sulfate are quite different in water samples collected from the two selected mine. According to sulfur isotope analysis, the dissolution of gypsum is the primary source of sulfate in samples from Hongfa mine, whereas sulfide oxidation contributed a large amount of sulfate to the mine water in Fenghuangshan mine. The dissolution of carbonates should be an important source of DIC in mine water and CO originating from organic mineralization might also have a certain contribution. This study elucidated the groundwater chemical evolution processes in high-sulfur coal-bearing strata and provided a foundation for further study of carbonates erosion and carbon emission during acidification of mine water.

Eco-hydrology and the effects on the national economy: case of the eastern region of Abakaliki Anticlinorium, Southeastern Nigeria

“…Apart from chloride suspectedly contributed mainly from influx of connate water, the evolutions of anions like SO 4 2− and heavy metals such as Pb and Zn have been associated with point source loading from mine water via anthropogenic (or mining) activities. This assertion concurs with the fact that mine water releases heavy metals (Blowes et al 2003) and sulphate ions by the oxidation of sulphur (Li et al 2018). In contrast, HCO 3 evolved from non-point sources through (mg/l) natural (geogenic) interaction of precipitation water with the calcareous sediments (Eq.…”

Experimental Study of Coal Sample Damage in Acidic Water Environments

“…Since this work only studied the influence of H + in solutions, the competing effects of ions that may exist in actual mine water, such as Ca 2+ , Mg 2+ , and HCO 3− , will not be discussed. Under the action of geochemistry and microbial catalysis, the redox environment of coal fields (including abandoned mines) changes, and the produced acid mine water is conducive to the transfer of metal ions to wider areas and water pollution (Galhardi and Bonotto 2016;Li et al 2018).…”

Performance and Mechanisms of PropS-SH/HA Coatings in the Inhibition of Pyrite Oxidation

“…Pyrite is a common symbiotic and associated metal sulfide mineral found in coal mines and other metal mines. In the presence of air, water, or microorganisms (such as Thiobacillus ferrooxidans), pyrite can undergo complex water–rock reactions such as leaching, oxidation, and hydrolysis, resulting in the formation of acid mine drainage (AMD). − AMD is a kind of mine wastewater with low pH and a high concentration of sulfate, iron ions, and various heavy metal ions, − which can cause the pollution of surface waters and groundwater while also posing a threat to human beings and ecosystems . Therefore, developing the technology to control AMD is an important issue.…”

“…1−3 AMD is a kind of mine wastewater with low pH and a high concentration of sulfate, iron ions, and various heavy metal ions, 4−6 which can cause the pollution of surface waters and groundwater while also posing a threat to human beings and ecosystems. 7 Therefore, developing the technology to control AMD is an important issue.…”