Impact of mitigation strategies on acid sulfate soil chemistry and microbial community.
Potential acid sulfate soils contain reduced iron sulfides that if oxidized, can cause significant environmental damage by releasing large amounts of acid and metals. This study examines metal and acid release as well as the microbial community capable of catalyzing metal sulfide oxidation after treating acid sulfate soil with calcium carbonate (CaCO3) or calcium hydroxide (Ca(OH)2). Leaching tests of acid sulfate soil samples were carried out in the laboratory. The pH of the leachate during the initial flushing with water lay between 3.8 and 4.4 suggesting that the jarosite/schwertmannite equilibrium controls the solution chemistry. However, the pH increased to circa 6 after treatment with CaCO3 suspension and circa 12 after introducing Ca(OH)2 solution. 16S rRNA gene sequences amplified from community DNA extracted from the untreated and both CaCO3 and Ca(OH)2 treated acid sulfate soils were most similar to bacteria (69.1% to 85.7%) and archaea (95.4% to 100%) previously identified from acid and metal contaminated environments. These species included a Thiomonas cuprina-like and an Acidocella-like bacteria as well as a Ferroplasma acidiphilum-like archeon. Although the CaCO3 and Ca(OH)2 treatments did not decrease the proportion of microorganisms capable of accelerating acid and metal release, the chemical effects of the treatments suggested their reduced activity.
Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden. Electronic address: xiaofen.wu@lnu.se.
Xiaofen
X
Wu
Energy & Environmental Technology, Vaasa University of Applied Sciences, Vaasa, Finland. Electronic address: pekka.sten@vamk.fi.
Pekka
P
Sten
R&D Department, Novia University of Applied Sciences, Vaasa, Finland. Electronic address: sten.engblom@novia.fi.
Sten
S
Engblom
Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Poland. Electronic address: ncnowak@cyf-kr.edu.pl.
Pawel
P
Nowak
Department of Geology and Mineralogy, Åbo Akademi University, Åbo, Finland. Electronic address: posterho@abo.fi.
Peter
P
Österholm
Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden. Electronic address: mark.dopson@lnu.se.
Mark
M
Dopson
D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation / Q000379:methods*; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis*; D013431:Sulfates / Q000032:analysis*
D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates
Acid; Acid sulfate soil; Acidophile; Metal; Molecular phylogeny