高砷沉积物中砷形态转化的微生物作用机制

Microbial Mediation and Mechanism on the Speciation of Arsenic from Arsenic-enriched Sediments

采用实验室恒温培育的方式,利用分子生物等技术,在厌氧条件下,研究了Fe(Ⅲ)和碳源对雄黄矿区沉积物中砷的释放。结果显示雄黄矿区沉积物中砷的释放主要是微生物的作用,并伴随铁的释放;在厌氧条件下添加电子供体乙酸钠后,主要以As(Ⅲ)的形式释放到水体中;厌氧环境下沉积物中砷的释放是铁还原菌Geobacteraceae和砷还原菌共同作用的结果,其中微生物直接还原As(Ⅴ)在控制砷迁移转化的过程中比Fe(Ⅲ)氧化物还原贡献更大,沉积物中主要优势种群是由δ变形菌门、Chloroflexi(绿弯菌门)和Firmicutes(厚壁菌门)所控制。

In this study,the effect of Fe(Ⅲ)and carbon sources on the sediments bacterial community has been studied with molecular biology approaches by using anaerobic incubation theunder a constant temperature.The results showed that the biotic and abiotic processes may play a role in arsenic mobilization,but microorganisms remain defining in catalysing the redox transformations that ultimately control the mobility of the arsenic.Sediments incubated under anaerobic conditions showed Fe(Ⅲ)reduction was concomitant with arsenic mobilization with time,principally as As(Ⅲ).The sediments bacterial community structure changed and some key bacterial abundance significantly increased with the changes in environmental conditions.These results suggested that the directly reduction of As(Ⅴ)made greater contributions to arsenic release from sediments than reductive dissolution of arsenic-rich Fe(Ⅲ)oxyhydroxides did.Alpha and gamma Proteobacteria and acidobacteria were found the dominant population in tailing sediment.