引用本文:王旭刚,孙丽蓉,张颖蕾,徐晓峰,郭大勇,石兆勇.豫西旱作褐土剖面土壤的氧化铁还原与亚铁氧化特征[J].土壤学报,2018,55(5):1199-1211.
WANG Xugang,SUN Lirong,ZHANG Yinglei,XU Xiaofeng,GUO Dayong,SHI Zhaoyong.Characterization of Reduction of Iron Oxide and Oxidation of Ferrous Iron in Upland Cinnamon Soil Profiles in West Henan, China[J].Acta Pedologica Sinica,2018,55(5):1199-1211
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豫西旱作褐土剖面土壤的氧化铁还原与亚铁氧化特征
王旭刚,孙丽蓉,张颖蕾,徐晓峰,郭大勇,石兆勇
河南科技大学农学院,河南科技大学农学院,河南科技大学农学院,河南科技大学农学院,河南科技大学农学院,河南科技大学农学院
摘要:
土壤铁氧化物的氧化还原过程不仅与重金属的生物有效性和有机污染物降解转化关系密切,也与旱地土壤肥力关系密切,因而备受关注。然剖面土壤耕层以下是否存在铁氧化物的还原、氧化过程,其特征如何尚未可知。本文采用恒温厌氧泥浆培养的方法研究旱地褐土剖面中铁的氧化还原特征。结果表明,旱地土壤剖面0~100 cm中均存在铁的厌氧还原过程,还原潜势、最大速率均随剖面深度增加而显著降低;剖面0~80 cm土层中均存在光合型Fe(II)氧化现象,0~40 cm土层Fe(II)氧化量和氧化速率显著高于40~80 cm。剖面的铁氧化还原过程不仅受有机碳含量影响,也受N、K等养分元素的影响。结果可为拓展对铁氧化还原微生物生境的认识、深入理解土壤剖面中铁氧化还原过程提供依据。
关键词:  旱地土壤  铁还原  土壤剖面  亚铁氧化  褐土
DOI:10.11766/trxb201712070430
分类号:
基金项目:国家自然科学基金项目(U1504402,41601309)
Characterization of Reduction of Iron Oxide and Oxidation of Ferrous Iron in Upland Cinnamon Soil Profiles in West Henan, China
Wang Xuang,Sun Lirong,Zhang Yinglei,Xu Xiaofeng,Guo Dayong and Shi Zhaoyong
Agricultural College,Henan University of Science Technology,Luoyang,Agricultural College,Henan University of Science Technology,Luoyang,Agricultural College,Henan University of Science Technology,Luoyang,Agricultural College,Henan University of Science Technology,Luoyang,Agricultural College,Henan University of Science Technology,Luoyang,Henan university of science and technology
Abstract:
【Objective】Iron redox processes are important microbial processes, which are closely related not only to bioavailablity of heavy metals and degradation of organic pollutants in anaerobic environment, but also to soil fertility of upland soils. Therefore, the issue has aroused much attention the world over. Iron redox process in plough layers of paddy fields and upland fields was already well documented, however, it is still unclear whether iron redox process exists in the soil underneath the plough layers, or what are characteristics of the iron redox processes. 【Method】In the present study, samples of upland cinnamon soils, collected from different layers of a 0~100 cm deep soil profile, were prepared into slurries, separately and then incubated anaerobically in darkness or in light, 0.5 mol·L-1 HCl extractable Fe(II) in the soisl samples was analyzed dynamically to study characteristics of the reduction and oxidation of iron oxide in the soil profile. To explore transformation of C, N and S coupled with the iron redox process in the profile, organic carbon, inorganic carbon, nitrate and sulfate in the profile soil samples before and after incubation were extracted by water and analyzed with a TOC analyzer and Ion Chromatography. 【Results】Fe(II) accumulation was found in all the samples during anaerobically incubation. Iron reduction potential decreased with soil depth in the profile. Fe(II) re-oxidation appeared only in the 0~80 cm soil layer of the profile under illuminated incubation. Ferrous oxidation decreased with depth in the profile from 20 cm to 80 cm. Water soluble organic carbon and iron oxide reduction both decreased with depth in the profile under incubation in light illuminated or in darkness. Water soluble inorganic carbon increased in the soil during the incubation in darkness, while it decreased in illuminated incubation. Water soluble nitrate decreased by 83.4%~98.6% in the soil incubated either in darknss or in light, and the range of the decrease narrowed with depth in the profile. The range of the decrease in water soluble sulfate narrowed with depth in the profile under incubation in darkness, while water soluble sulfate increased with depth in the profile within the range from 0~40 cm under illuminated incubation. Correlation analysis shows that iron reducing potential and ferrous oxidation was positively and significantly related to increase and decrease in water soluble inorganic carbon, respectively. Rate constant, max velocity of iron reduction and ferrous oxidation velocity was positively and significantly related to water soluble organic carbon. While decrease in nitrate was positively related to reducing potential, max velocity of iron reduction, re-oxidation and velocity of iron oxidation. Sulfate reduction was positively and significantly related to reduction potential, and max velocity of iron reduction under incubation in darkness, while it was negatively to amount and rate of ferrous oxidation under illuminated incubation. 【Conclusions】Results show that iron reduction process exists throughout the whole profile from 0 to 100 cm, and iron reduction potential, and maximum velocity of iron reduction decreased significantly with depth in the profile. Phototrophic ferrous oxidation appeared in the 0~80 cm soil layer in the profile; the amount and rate of ferrous oxidation was much higher in the 0~40 cm soil layer in the profile than in the 40~80 cm soil layer. Correlation analysis of iron redox process and soil properties in the vertical direction of the upland cinnamon soil shows that iron redox process in the profile was not only affected by soil organic carbon, but also limited by the contents of soil nutrients including N and K. The findings may help improve the cognition of the habitat of iron redox microbes, and serve as certain basis for in-depth understanding of the iron redox processes in upland cinnamon soil.
Key words:  Upland soil  Iron reduction  Soil profile  Ferrous iron oxidation  Cinnamon soil