微生物在不同pH下对水稻土胶体中砷释放的影响  

Effects of microorganisms on the release of arsenic from paddy soil colloids at different pH levels

作　　者：陈爽 张翅鹏[1,2] 黄臣臣[1,3] 张凯璇 杨泽延 罗江兰 CHEN Shuang;ZHANG Chipeng;HUANG Chenchen;ZHANG Kaixuan;YANG Zeyan;LUO Jianglan(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China;Key Laboratory of Karst Georesources and Environment,Ministry of Education,Guiyang 550025,China;Guizhou Karst Environmental Ecosystems Observation and Research Station,Ministry of Education,Guiyang 550025,China)

机构地区：[1]贵州大学资源与环境工程学院,贵阳550025 [2]喀斯特地质资源与环境教育部重点实验室,贵阳550025 [3]贵州喀斯特环境生态系统教育部野外科学观测研究站,贵阳550025

出　　处：《农业环境科学学报》2022年第5期959-966,共8页Journal of Agro-Environment Science

基　　金：国家自然科学基金项目(41403088);国家自然科学基金委员会-贵州省人民政府喀斯特中心项目(U1612442)。

摘　　要：为探讨水稻土胶体与类金属砷(As)的生物地球环境行为,本研究对比分析了微生物在初始pH=3和初始pH=7的不同酸碱条件下对土壤胶体负载As释放的作用差异,并揭示其内在机制。结果表明:在pH=3条件下微生物作用相对较弱,对胶体悬液pH与Eh影响较小,与无菌对照组相比,溶液中Fe^(2+)与As含量均有所提高,且释放的As主要为氧化态As(Ⅴ);在pH=7条件下微生物活性较强,至28 d时可使胶体悬液pH升至8.12,Eh降至-55 mV,形成强还原环境,铁还原溶解量明显增多,Fe^(2+)含量是无菌对照组的2.79倍,并且胶体中吸附态As随着Fe的还原溶解而释放,主要为还原态As(Ⅲ)。相关性分析表明,土壤胶体中As的释放与铁氧化物的还原转化有关,溶液中As释放量与Fe^(2+)含量呈显著正相关关系,尤其在中性条件下As(Ⅲ)含量与Fe^(2+)极显著正相关(r=0.798^(**),P<0.01)。研究表明,在中性环境条件下较强的微生物活性可提高土壤胶体中铁氧化物的异化还原,同时增强As的释放与转化。To explore the biogeoenvironmental behavior of paddy soil colloids and metal-like arsenic,this study mainly analyzed the differences in the effects of microorganisms on the release of arsenic from soil colloids under different acid-base conditions of initial pHs 3 and 7,respectively,and reveals the internal mechanism.The results showed that the microbial effect was relatively weak at an initial pH of 3 and had little effect on the pH and Eh of the colloidal suspension.Compared with the aseptic condition,the content of Fe^(2+)and As in the solution increased,and the released As was mainly in the oxidation state As(Ⅴ).At an initial pH of 7,the microbial activity was relatively strong.By the 28th day,the pH of the colloidal suspension increased to 8.12,and the Eh was reduced to-55 mV,forming a strong reducing environment.Therefore,the amounts of iron reduction and dissolution increased significantly.The Fe^(2+)content was 2.79 times that of the sterile control group.The adsorbed arsenic in the colloid is released with the reduction and dissolution of iron and is finally formed into reduced As(Ⅲ).Correlation analysis showed that the release of arsenic from soil colloids was related to the reduction and transformation of iron oxides.There was a significant positive correlation between the amount of arsenic released in the solution and Fe^(2+)content.In particular,under neutral conditions,the As(Ⅲ)concentration was also significantly positively correlated with Fe^(2+)(r=0.798^(**),P<0.01).Therefore,strong microbial activity under neutral environmental conditions can increase the dissimilatory reduction of iron oxides in soil colloids and simultaneously enhance the release and transformation of arsenic.

关 键 词：微生物 土壤胶体 铁还原 As 释放 PH 

分 类 号：X142[环境科学与工程—环境科学] P593[天文地球—地球化学]