初始pH值对碱性和酸性水稻土微生物铁还原过程的影响  

Effect of initial pH value on microbial Fe(Ⅲ) reduction in alkaline and acidic paddy soils

作　　者：吴超[1] 曲东[1] 刘浩[1] 

机构地区：[1]西北农林科技大学资源环境学院,杨凌712100

出　　处：《生态学报》2014年第4期933-942,共10页Acta Ecologica Sinica

基　　金：国家自然科学基金面上资助项目(40971158;41171204)

摘　　要：酸碱度(pH值)是水稻土铁还原过程的重要影响因素之一。通过模拟水稻土淹水厌氧培养,以Al2(SO4)3和Na2CO3溶液分别调节碱性和酸性水稻土pH值至强酸性(pH值<5.0)、酸性(pH值5.0—6.5)、中性(pH值6.5—7.5)、碱性(pH值7.5—8.5)、强碱性(pH值>8.5),以此来研究5种初始pH值对水稻土泥浆铁还原过程的影响;通过微生物群落厌氧培养研究了2种水稻土菌悬液在6种pH值条件下的铁还原能力差异。结果表明,碱性水稻土铁还原潜势(a)、最大铁还原速率(V max)随初始pH值的降低而下降,而达到最大铁还原速率所需的时间(T Vmax)则延长。提高酸性水稻土初始pH值使铁还原V max增加而T Vmax缩短,但土壤中无定形氧化铁均能还原,初始pH值与V max具有显著正相关关系。碱性和酸性水稻土的土壤菌悬液在试验pH值范围内厌氧培养,其铁还原能力在培养初期差异不显著,但培养后期的差异明显,且最终都能把培养液中氧化铁完全还原。随着初始pH值升高T Vmax延长,V max则降低,且均显著负相关,但碱性水稻土微生物群落的V max在pH值6.00时最大。初始pH值和土壤类型对水稻土铁还原过程具有显著影响,且对土壤菌悬液微生物群的铁还原具有一定影响。The pH value is one of the most important factors affecting iron reduction in paddy soils. The objective of this study was to determine how changes in initial pH affected iron reduction in paddy soils from Jilin （JL） and Jiangxi （JX） provinces. Anaerobic incubations were conducted using （1） soil slurries and （2） mixed microbial cultures that had been isolated from each soil type. The pH value of the alkaline JL samples was reduced with Al2（SO4）3. The pH value of the acidic JX samples was increased using Na2CO3. The pH values of the soil slurries were strongly acidic （pH 〈 5.0）, acidic （pH 5.0-6.5）, neutral （pH 6.5-7.5）, alkaline （pH 7.5-8.5）, and strongly alkaline （pH 〉 8.5）. The mixed microbial cultures were incubated in medium with pH ranging between 4.84-10.51. The Fe（Ⅱ） concentration and pH value of the samples were measured at regular intervals. A logistic model was used to analyze the characteristics of Fe（Ⅲ） reduction. The results showed that iron reduction potential and the maximum rate of iron reduction decreased as the initial pH value decreased. The time to reach the maximum rate of iron reduction increased as the initial pH value of the JL soil slurry declined. The maximum rate of iron reduction in the JL slurry decreased by nearly 50% as the pH value decreased, declining from （0.05±0.00） mg·g-1·d-1 at pH 10.51 to （0.02±0.00） mg·g-1·d-1 at pH 7.00. All amorphous iron oxides were reduced in the JX paddy soils, although the maximum rate of iron reduction increased and the time to reach the maximum rate of iron reduction decreased as the initial pH increased. The maximum rate of iron reduction in the JX soil was highest （（0.46±0.04） mg·g-1·d-1） and the time to reach the maximum rate of iron reduction was shortest （（3.65±0.21） d） at pH 8.19. There was a highly significant positive correlation between the maximum rate of iron reduction and the initial pH value of both soils （JL r=0.897, P=0.000; JX r=0.903, P=0.000�

关 键 词：初始PH值 水稻土 异化铁还原 泥浆和土壤菌悬液厌氧培养 

分 类 号：S154.3[农业科学—土壤学]