石灰性水稻土中硝酸盐依赖型与光合型亚铁氧化过程浅析
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1.河南科技大学农学院;2.1. 河南科技大学农学院,河南洛阳 471000;3.2. 洛阳市植物营养与环境生态重点实验室,河南洛阳 471000;4.3. 洛阳市共生微生物与绿色发展重点实验室,河南洛阳 471000

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国家自然科学基金项目(面上项目,重点项目,重大项目)


A Brief Analysis of Between Nitrate-Dependent and Photosynthetic Fe(II) Oxidation Processes in a Paddy Soil
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1.Agricultural College,Henan University of Science Technology,Luoyang;2.1. Agricultural College, Henan University of Science and Technology, Luoyang, Henan 471000, China;3.2. Luoyang Key Laboratory of Plant Nutrition and Environmental Ecology, Luoyang, Henan 471000, China;4.1. Agricultural College, Henan University of Science and Technology, Luoyang, 3. Luoyang Key Laboratory of Symbiotic Microbes and Green Development, Luoyang, Henan 471000, ChinaHenan 471000, China

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    摘要:

    厌氧条件下土壤中铁氧化还原过程与土壤氮循环关系密切,且硝酸盐依赖型亚铁氧化(nitrate-dependent ferrous oxidation, NDFO)和光合型亚铁氧化(photosynthetic ferrous oxidation, PFO)是亚铁氧化的两个重要的生物途径,然而目前关于石灰性水稻土中NDFO与PFO之间的关系仍不明晰。以采自黄河中下游地区河南省孟津县的水稻土为样品,设置培养前添加和培养过程中添加10 mmol·L-1的NO3-/NH4+的恒温厌氧泥浆培养试验,通过监测泥浆中Fe(II)、O2、NO3-和NO2-的动态变化与培养后的NH4+含量探究了NO3-在石灰性水稻土Fe(II)氧化过程的作用及其与光合型亚铁氧化的关系。结果表明:避光条件下石灰性水稻土中存在NDFO,但产生的Fe(III)可在NO3-消耗殆尽时被再次还原而掩盖Fe(II)氧化现象。光照条件下NDFO和PFO可同时存在,PFO可致1.99 mg·g-1 Fe(II)氧化,NO3-的加入可使Fe(II)氧化量增加0.57 mg·g-1。光照可抑制NO3-的还原而抑制NDFO。研究结果对于进一步理解湿地铁的氧化还原及其耦合的氮素转化过程有重要意义。

    Abstract:

    【Objective】Iron redox processes under anaerobic conditions are closely correlated to nitrogen cycling in soils. Both nitrate-dependent ferrous oxidation (NDFO) and photosynthetic ferrous oxidation (PFO) are crucial pathways of biological ferrous iron oxidation. However, whether NDFO occurs in calcareous paddy soils and its relation to PFO is still ambiguous. 【Method】 We collected soil samples from Mengjin County, Henan Province, within the middle and lower reaches of the Yellow River. The soil samples were made into slurries using 10 mmol·L-1 NO3—/NH4+ solution or water at the very beginning. Then the slurries were anaerobically incubated under darkness or illuminated. On the 7th day of the incubation, we injected 0.5 mL 70 mmol·L-1 NO3— or NH4+ into a part of those slurries made with water to adjust their external NO3— or NH4+ content to 10 mmol L-1. To assess the iron reduction, and ferrous oxidation, Fe(II) in the slurries was measured dynamically using the phenanthroline colorimetric method. To evaluate the nitrogen transformation, NO3- and NO2- were analyzed dynamically using an ion chromatograph equipped with an electrical conductivity detector, and NH4+ was measured after the incubation by 1 mol·L-1 KCl extraction-Kjeldahl method. To fractionate the PFO, O2 in the headspaces were determined dynamically using a portable fiber-optic trace oxygen meter. 【Result】The results showed that, though no apparent ferrous oxidation was observed, iron reduction rate decreased by 0.28 mg·g-1·d-1 and 0.33 mg·g-1·d-1. Also, the iron reduction rate was decreased by 0.15 d-1, 0.17 d-1 in slurries under darkness with NO3- or NH4+ amended at the very beginning. Ferrous iron was oxidized by 2.21 mg·g-1 and 0.68 mg·g-1 in slurries with NO3— or NH4+ injected on the 7th day of the dark incubation and by 1.99 mg·g-1 in slurries incubated under light. In addition, Fe(II) in the slurries was negatively correlated to O2 in the headspace. Importantly, the reduction of NO3— to NH4+ occurred in the slurries with NO3— injected on the 7th day of dark incubation. 【Conclusion】 Ferrous oxidation caused by NDFO was observed in the calcareous paddy soil amended with 10 mmol·L-1 NO3— and incubated anaerobically under darkness. However, the oxidation could be inhibited since the ferric iron resulting from NDFO would be reduced rapidly when the NO3— becomes depleted. Both NDFO and PFO occurred in the calcareous paddy soil incubated under illumination and the PFO resulted in 1.99 mg·g-1 ferrous iron oxidized. Ferrous oxidation in soils under illumination was increased by 0.57 mg·g-1 when NO3— was injected. These results help to further understand the redox processes and the coupled nitrogen transformation in wetland soils.

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陈志怀,王旭刚,孙丽蓉,董乐恒,郭大勇,石兆勇.石灰性水稻土中硝酸盐依赖型与光合型亚铁氧化过程浅析[J].土壤学报,,[待发表]
Chen Zhihuai, Wang Xugang, Sun Lirong, Dong Leheng, Guo Dayong, Shi Zhaoyong. A Brief Analysis of Between Nitrate-Dependent and Photosynthetic Fe(II) Oxidation Processes in a Paddy Soil[J]. Acta Pedologica Sinica,,[In Press]

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