摘要
【目的】淹水稻田中Fe(Ⅲ)还原过程与有机质的厌氧分解和氮、磷、硫等营养元素的有效性密切相关。通过探讨水溶性有机碳(DOC)对Fe(Ⅲ)还原过程的贡献,以期为深入理解淹水稻田中铁循环耦联的碳、氮、磷、硫循环提供理论基础。【方法】采集我国不同植稻区的20个典型水稻土,通过有机碳分析仪及三维荧光光谱扫描比较分析不同水稻土DOC的含量及荧光特性;并模拟稻田淹水过程对水稻土进行厌氧淹水培养,采用微生物生长模型对不同水稻土厌氧培养过程中Fe(Ⅲ)还原特征进行表征;依据相关分析和冗余分析,明确水稻土DOC与Fe(Ⅲ)还原过程的关系。【结果】不同水稻土DOC含量为0.250~1.082 g/kg,仅占土壤有机碳的2.06%~6.86%。三维荧光光谱扫描鉴定得到不同水稻土DOC中4个共有的类腐殖酸荧光组分,其中陆源的UVC类腐殖酸和UVC+UVA类腐殖酸组分在不同水稻土中具有较高荧光强度,分别为0.799~4.570和0.830~5.273。水源的可见光区类腐殖酸和UVA腐殖酸的含量相对较低。各类腐殖酸来源以外源输入为主,内源输入为辅。不同水稻土铁还原潜势a、最大Fe(Ⅲ)还原速率(Vmax)及达到最大Fe(Ⅲ)还原速率对应的时间(TVmax)间均差异显著,淹水5 d时水稻土中易被还原的非晶态氧化铁已基本被还原。DOC的腐殖化系数与Fe(Ⅲ)还原特征参数存在显著相关性。其中以陆源的大分子量UVC类腐殖酸对a和Vmax的贡献最高,陆源的UVC+UVA类腐殖酸和水源的UVA腐殖酸与a和Vmax的相关关系也达到显著或极显著水平,而DOC含量的贡献最小。【结论】水稻土DOC的腐殖化程度及其中陆源腐殖酸类组分的荧光强度与Fe(Ⅲ)还原潜势和Fe(Ⅲ)还原反应速率呈正相关。水稻土DOC除了作为Fe(Ⅲ)还原过程的电子供体外,其还以电子穿梭体的形式在Fe(Ⅲ)还原过程中起重要作用。
[Objective] Iron[Fe（Ⅲ）] reduction is closely associated with the degradation of soil organic carbon and the bioavailability of nitrogen, inorganic phosphate and sulfur in submerged paddy field. This study is to investigate the contribution of water dissolved organic carbon （DOC） to Fe （Ⅲ） reduction in paddy soil, and thus to provide a better understanding on the cycles of carbon, nitrogen, phosphorus and sulfur, which are mediated by a Fe cycle coupling in paddy soils.[Methods] Total 20 samples of paddy soils were collected in the typical paddy fields representation major rice production regions in China. The DOC contents in paddy soils were determined by the total organic carbon analyzer, and the DOC composition was analyzed by the fluorescence indicator and a PARAFAC analyzer of EEM spectra. Anaerobic paddy soil was incubated under anaerobic condition, and accumulation changes of Fe （Ⅲ） accompanying incubation process were measured. The Fe （Ⅲ） reduction profiles were also presented by modeling with Logistic Model. Both correlation and redundancy analyses were used to reveal the specific contribution of the humic acid-like components to microbial Fe （Ⅲ） reducing characteristics.[Results] Data showed that the contents of DOC in paddy soils were ranged from 0.250 to 1.082 g/kg, and accounted for 2.06%-6.86% of the contents of soil organic carbon. The fluorescence EEM spectra of the extract solutions from paddy soils were decomposed into a model with four components by analyzing the residuals. The fluorescence intensity of the terrestrial UVC humic acid-like component and UVC＋UVA humic acid-like component were represented by 0.799-4.570 and 0.830-5.273, respectively, and higher than those of aquatic visible humic acid-like component and UVA humic acid-like component. The fluorescence strength of paddy soils revealed that water dissolved organic carbon was terrestrially-derived rather than microbial-derived. There were significant differences in the Fe （Ⅲ） reduction characte
作者
曲植
李丽娜
贾蓉
QU Zhi;LI Li-na;JIA Rong(College of Natural Resources and Environment, Northwest A＆F University, Yangling, Shaanxi 712100, China)
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2018年第2期346-356,共11页
Journal of Plant Nutrition and Fertilizers
基金
国家自然科学基金项目(41571239)资助
关键词
水溶性有机碳
三维荧光光谱
Fe(Ⅲ)还原
水稻土
water dissolved organic carbon
fluorescence excitation-emission matrix
Fe （III） reduction
paddy soil
