Geochemical behavior of arsenic in reducing sulfidic sediments of reservoir contaminated by acid mine drainage

• Published in: Environmental earth sciences Vol. 71; no. 10; pp. 4341 - 4351
• Main Authors: Zhang, C. P, Wu, P, Tang, C. Y, Xie, H. H, Zeng, Z. C, Yang, S. Z
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.05.2014; Springer Berlin Heidelberg; Springer; Springer Nature B.V
• Subjects: Acid mine drainage; adsorption; Arsenic; Biogeosciences; Contaminated sediments; Crystallization; Diagenesis; Diffusion; Dissolution; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Science and Engineering; Exact sciences and technology; ferric oxide; Geochemistry; Geology; Hydrology/Water Resources; hydrolysis; Iron; Iron sulfides; Limestone; Neutralization; Original Article; oxides; Pollution, environment geology; Pore water; Reservoirs; Sediments; Speciation; Sulfates; sulfide minerals; Surface chemistry; Terrestrial Pollution; thermodynamics; China; Far East; Asia; Guizhou China; Arsenic; Acid mine drainage; Diffusion; Reductive dissolution; Surface complexation; Reservoir sediment; diffusion; mobility; carbonate rocks; mine drainage; oxides; ferric iron; reservoirs; thermodynamics; sulfates; pollution; complexing; drill cores; acids; limestone; pH; sulfides; diagenesis; models; iron sulfides; neutralization; dissolution; concentration; arsenic; speciation; sedimentary rocks; crystallization; hydrolysis
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-013-2828-7

The sediment from an acid mine drainage affected reservoir of Guizhou province of China has the iron and arsenic concentration of about 400 and 2.6 g/kg, respectively. Sediment cores were collected, and were used to study the arsenic behavior in the seriously acidified reservoir from the viewpoint of chemical thermodynamics. The limestone neutralization and ferric iron hydrolysis regulated the porewater pH from about 2.9–5.8. The reductive dissolution of As–Fe-rich (hydr)oxides under the mild acidic conditions was the main mechanism for the release of absorbed arsenic into porewater. The maximum concentrations of iron, sulfate and arsenic reached to about 2,800, 9,000 and 1 mg/l, respectively. Arsenic speciation transformation and hydrous ferric oxide (HFO) crystallization enhanced the arsenic mobility in sediment. In addition, the iron sulfide minerals diagenesis could play a role in removing the dissolved arsenic from porewater. The actual distribution of arsenic concentration in porewater was well simulated using the model of surface complexation of arsenic to HFO. Although arsenic concentration in porewater could be above 100 times higher than that of reservoir water, it was not easy to release into the reservoir water through diffusion, because the shallow sediment had relatively strong arsenic adsorption capacity, and new HFO could be generated continuously at the sediment water interface.