引用本文:王旭刚,孙丽蓉,马林娟,郭大勇,徐晓峰.黄河中下游湿地土壤铁还原氧化过程的温度敏感性[J].土壤学报,2018,55(2):380-389.
WANG Xugang,SUN Lirong,MA Linjuan,GUO Dayong,XU Xiaofeng.Temperature Sensitivity of Iron Redox Processes in Wetland Soil in the Middle and Lower Reaches of the Yellow River[J].Acta Pedologica Sinica,2018,55(2):380-389
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黄河中下游湿地土壤铁还原氧化过程的温度敏感性
王旭刚, 孙丽蓉, 马林娟, 郭大勇, 徐晓峰
河南科技大学农学院
摘要:
土壤中铁的还原氧化过程因与重金属的生物有效性、有机污染的降解及含碳温室气体排放等环境问题关系密切而备受关注。温度可能通过影响铁还原菌或者Fe(II)氧化菌的活性、底物的生物可用性等而影响铁的还原过程。以黄河中下游地区新乡市原阳大米产区的湿地土壤为样品,利用厌氧泥浆控温培养试验方法研究了黄河中下游湿地中土壤铁还原氧化过程的温度敏感性。结果表明:黄河中下游湿地土壤铁的还原容量在16 ℃~31 ℃范围内不受温度影响,但在16 ℃~40 ℃之间升高温度可显著增加铁还原过程的最大速率、速率常数,亦可缩短最大速率出现的时间。铁还原的温度敏感系数介于1.18~3.05之间,且随温度上升而升高。光照可降低铁还原的温度敏感性,平均降幅39.0%。光照时土壤中Fe(II)氧化对温度不敏感。光照条件和铁氧化物的种类和数量可能是影响土壤有机碳矿化的因素之一。研究结果对于深入理解土壤铁的生物地球化学循环及其与土壤呼吸的关系具有重要意义。
关键词:  温度敏感性  湿地  铁还原  铁氧化  异养呼吸
DOI:10.11766/trxb201708110352
分类号:
基金项目:国家自然科学基金项目(U1504402、41601309)
Temperature Sensitivity of Iron Redox Processes in Wetland Soil in the Middle and Lower Reaches of the Yellow River
WANG Xugang, SUN Lirong, MA Linjuan, GUO Dayong, XU Xiaofeng
Agricultural College, Henan University of Science & Technology
Abstract:
【Objective】 As iron reduction and oxidation processes in soil are closely related to bio-availability of heavy metals, degradation of organic pollutants and emission of carbon-containing greenhouse gases, they have aroused increasing concern among scholars. Temperature is a factor that may affect iron redox in soil by influencing activity of ferric reduction and ferrous oxidation bacteria, and bio-availability of substrates. Temperature sensitivity of heterotrophic respiration, which is driven by iron redox processes, has been intensively investigated, but little has been done on temperature sensitivity of iron redox processes in wetland soils. 【Method】So in this paper, soil samples were collected from paddy fields or wetlands in Yuanyang County of Xinxiang City, Henan Province, a major rice production area in the middle and lower reaches of the Yellow River for analysis of temperature sensitivity of iron redox processes in the soil through temperature-controlled anaerobic incubation. Samples of the paddy or wetland soil were prepared into slurry and then incubated anaerobically in darkness or under illumination at a preset temperature, and ferrous in the slurry was analyzed periodically to monitor temperature sensitivity of iron oxides reduction and ferrous oxidation in darkness and under illumination. Air in the headspace of the vials after 3 days of incubation was analyzed for O2 using an optical fiber oxygen detector (PreSens Microx 4, Germany Regensburg), and for CO2 using a gas chromatographer (GC7900, China Shanghai Tianmei) equipped with a TCD detector. Water soluble organic and inorganic carbon in the slurry was measured with a TOC analyzer (TOC-VCPH Japan Shimadzu) after the incubation. 【Results】Results show that temperature varying in the range of 16 oC ~ 31 oC did not have much effect on ferric reduction capacity in the soil samples, but it did increase the maximum rate and rate constant of iron reduction significantly, and advance the peaking time, when increasing from 16 oC to 40 oC. O2 was found accumulating in the headspace after 3 days of anaerobic incubation in light, and the accumulation increased with increasing incubation temperature. Water soluble inorganic carbon and CO2 increased dramatically with rising temperature in slurries under incubation in darkness, but no detectable CO2 and only little WSIC was found in the vial under illuminated incubation. 【Conclusion】 Temperature-sensitivity coefficient of iron reduction increased from 1.18 to 3.05 with rising temperature, but decreased under illumination by 39.0% on average. Temperature insensitivity of ferrous oxidation was observed during incubation in light. Quality and quantity of iron oxides and illumination conditions are supposed to be potential key factors affecting mineralization of organic carbon in wetland soils. All the findings in this paper could be of great significance to further efforts to understand biogeochemical cycle of iron in soil and its relationship with soil respiration.
Key words:  Temperature sensitivity  Wetland  Ferric reduction  Ferrous oxidation  Heterotrophic respiration