Effect of Arsenic Pollution Extent on Microbial Community in Shimen Long-Term Arsenic-Contaminated Soil

In order to investigate arsenic migration and transformation behavior under the action of microorganisms in Shimen long-term arsenic-contaminated soil under the condition of avoiding any influence of complicated soil environmental factors except increasing soil arsenic pollution degree, exogenous arsenic(III) or arsenic(V) stress experiments were carried out under the same experimental condition using the same soil sample. The changes of microbial community with exogenous arsenic concentrations and stress time were regularly monitored and comparatively analyzed. The soil microbial community shows extremely high diversities, and arsenic pollution degree affects microbial community composition rather than microbial diversity due to the long-term adaptation of microorganism to the arsenic-contaminated soil. Acidiobacteria and Nitrospirae play a key role in soil arsenic migration and transformation. Nitrospirae through producing NO3− takes part in the oxidation of As(III), and Acidiobacteria oxidizing sulfide minerals, as well as the adsorption and deposition of As(V), can enhance the soil acidity to promote soil arsenic migration and transformation, which can bring about the significant change of soil microbial community composition. Finally, its microbial community should tend to maintain a new pseudo-dynamic balance after a long time and a long-term arsenic-contaminated soil must be an arsenic oxidation-state soil. This work helps us understand why total arsenic, total organic carbon(TOC), NO3−, and pH are the key environmental factors that indirectly control the mobilization and release of arsenic via influencing the structures of the microbial communities in Shimen arsenic-contaminated soil.