비소오염토양에서 반복적인 Redox 환경 변화가 토양 미생물 군집과비소 및 철의 순환에 미치는 영향

Abstract

In a redox transition zone, geochemical reactions are facilitated by active bacteria that mediate reactions involvingelectrons, and arsenic (As) and iron (Fe) cycles are the major electron transfer reactions occurring at such a site. In thisstudy, the effect of repetitive redox changes on soil bacterial community in As-contaminated soil was investigated. Theresults revealed that bacterial community changed actively in response to redox changes, and bacterial diversity graduallydecreased as the cycle repeated. Proportion of strict aerobes and anaerobes decreased, while microaerophilic species suchas Azospirillum oryzae group became the predominant species, accounting for 72.7% of the total counts after four weeksof incubation. Bacterial species capable of reducing Fe or As (e.g., Clostridium, Desulfitobacterium) belonging to diversephylogenetic groups were detected. Indices representing richness (i.e., Chao 1) and phylogenetic diversity decreased from1,868 and 1,926 to 848 and 1,121, respectively. Principle component analysis suggests that repetitive redox fluctuation,rather than oxic or anoxic status itself, is an important factor in determining the change of soil bacterial community, whichin turn affects the cycling of As and Fe in redox transition zones.