典型土壤有机质组分对砷还原菌还原砷的影响机制  

Impact of typical soil organic matter components on reduction of arsenic by As(Ⅴ)-reducing bacteria and its mechanism

作　　者：黄煦涵 蔡晓琳 刘小茼 常旭卉 尹乃毅 周怡 肖鹏 崔岩山 HUANG Xuhan;CAI Xiaolin;LIU Xiaotong;CHANG Xuhui;YIN Naiyi;ZHOU Yi;XIAO Peng;CUI Yanshan(College of Resources and Environment,University of Chinese Academy of Sciences,Beijing,101408,China)

机构地区：[1]中国科学院大学资源与环境学院,北京101408

出　　处：《环境化学》2024年第8期2672-2681,共10页Environmental Chemistry

基　　金：国家自然科学基金(42107432);中央高校基本科研业务费专项资金资助.

摘　　要：为了探究土壤中不同类型有机质组分对砷还原菌还原As(Ⅴ)的影响及其机制,选择了腐殖酸(humus acid,HM)、胡敏酸(humic acid,HA),柠檬酸(citric acid,CA)、聚天冬氨酸(polyaspartic acid,PA)、多聚半乳糖醛酸(polygalacturonic acid,PGA)、谷氨酸(glutamic acid,Glu)6种典型土壤有机质组分作为研究对象,首先研究了这几类物质在中性pH条件下对液相As(Ⅴ)、As(Ⅲ)的吸附/络合作用及形态转化,并进一步探究了其对砷还原菌Desulfitobacterium sp.DJ-3还原液相As(Ⅴ)的影响及机制.结果表明,HM、HA、CA、PA能够络合As(Ⅴ)和As(Ⅲ),Glu仅能够络合As(Ⅲ),而PGA对As(Ⅴ)及As(Ⅲ)均无络合作用.此外,除了HM、HA能够还原As(Ⅴ)并氧化As(Ⅲ),其余有机质组分仅对As(Ⅴ)存在还原作用.在砷还原菌还原As(Ⅴ)的过程中,6种有机质组分可以作为电子供体促进砷还原菌对As(Ⅴ)的还原,CA、Glu还可以作为易利用的碳源促进细菌细胞个数增加,而HM、HA可能还起到电子穿梭体的作用,因而能更快地促进液相As(Ⅴ)被还原.本研究有助于明确不同土壤有机质组分对砷还原菌还原As(Ⅴ)的影响并为土壤中无机砷的环境行为预测提供理论基础.To explore the impact of different types of soil organic matter components on arsenic speciation transformation and its mechanisms,six kinds of typical soil organic matter components,including humus acid(HM),humic acid(HA),citric acid(CA),polyaspartic acid(PA),polygalacturonic acid(PGA)and glutamic acid(Glu),were selected.Their effects on the adsorption/complexation and speciation transformation of aqueous As(Ⅴ)and As(Ⅲ)under neutral pH condition were investigated,and the impact of different soil organic matter on the reduction of aqueous As(Ⅴ)by As(Ⅴ)-reducing bacteria Desulfitobacterium sp.DJ-3 and the relevant mechanisms were further explored.The results showed that HM,HA,CA and PA can form complexes with both As(Ⅴ)and As(Ⅲ),Glu can form complexes only with As(Ⅲ),while PGA can’t form complexes with As(Ⅴ)and As(Ⅲ).In addition,except that HM and HA can reduce As(Ⅴ)and oxidize As(Ⅲ),other organic matter components can only reduce As(Ⅴ).In the process of As(Ⅴ)reduction by As(Ⅴ)-reducing bacteria,all six organic matter components can be used as electron donors to promote microbial As(Ⅴ)reduction.As easily available carbon sources,CA and Glu can also increase the cell number of bacteria,while HM and HA may serve as electron shuttle to accelerate the reduction of aqueous As(Ⅴ).Our study can help to clarify the impact of different soil organic matter components on As(Ⅴ)reduction by As(Ⅴ)-reducing bacteria,which will provide a theoretical basis for the prediction of environmental behavior of inorganic arsenic in soil.

关 键 词：砷 有机质组分 砷还原菌 电子供体 碳源 电子穿梭. 

分 类 号：X-1[环境科学与工程] O6[理学—化学]