土壤腐殖质氧化还原电位及其相应电子转移能力分布
Distribution of soil humic acids redox potentials and corresponding electron transfer amounts
-
摘要: 本实验以土壤提纯腐殖酸及国际标准腐殖酸(Pahokee Peat Humic Acid, PPHA)为研究对象,测定腐殖酸与3种不同氧化还原Eh的铁矿物(水铁矿(Ferrihydrite)Eh0'=0 mV,赤铁矿(Fe2O3) Eh0'=-287 mV,磁铁矿(Fe3O4)Eh0' =-314 mV及溶解性铁铁氰化钾Eh0'(Ferricyanide =+430 mV)的氧化还原反应,结合Eh-pH计的实验体系,分析腐殖质分子氧化还原官能团的分布规律.磁铁矿同时拥有二价和三价铁离子,具有与腐殖质发生氧化或者还原反应的条件.不同土壤腐殖酸与磁铁矿反应表现的还原/氧化能力不同,这是由于腐殖酸的不同Eh引起,在此基础上测量显示原态下腐殖酸Eh值大约为245 mV, H2还原后,Eh值降低至-620 mV,表明腐殖酸的氧化还原Eh是不同种类和数量的氧化还原官能团Eh叠加值.分析标准腐殖酸在不同氧化还原Eh下的氧化/还原能力显示原态下标准腐殖酸的氧化还原Eh分布比较均匀,还原态腐殖酸在Eh > 0范围存在易于被氢气还原的官能团,具有显著的还原能力.Abstract: Humic substances (HS) can be reduced by microorganisms and oxidized by electron acceptors such as Fe(Ⅲ) due to their redox properties. They can stimulate the series reactions and therefore have effects on the fate of redox active compounds under different conditions. The extent of redox reaction depended on the difference of redox potentials between iron and HS. However, because of the complicated structures of HS and unknown information about their redox potentials, it is still not available to clearly estimate and measure their redox potentials and the corresponding electron transfer amounts of redox functional groups. In order to understand the distribution of redox functional groups based the values of redox potentials, extracted soil humic acids (HA) and Pahokee Peat Humic Acid (PPHA) were conducted to react with iron compounds with different redox potentials, e.g. ferrihydrite Eh0'(Ferrihydrite)=0 mV,hemitate Eh0'(Fe2O3) =-287 mV, magneitite Eh0'(Fe3O4) =-314 mV and dissolved ferricyanide Eh0' (K3[Fe(CN)6]])=+430 mV. Measurements of Eh values by using Eh-pH meter showed that native and reduced HA had Eh of 245 mV and-620 mV, respectively, and that all of the HA studied had comparable Eh, suggesting that the measured Eh represent a combination of different redox potentials of various redox functional groups.
-
Key words:
- humic substances /
- iron minerals /
- redox potentials /
- redox reaction
-
-
[1] Stevenson F J, Humus chemistry: Genesis, composition, reactions[M]. 2nd Edition. New York: Wiley, 1994:17 [2] Kappler A, Marcus B, Bernhard S, et al. Electron shuttling via humic acids in microbial iron(Ⅲ) reduction in a freshwater sediment[J]. FEMS Microbiology Ecology, 2004, 47: 85-92 [3] 窦森, 土壤有机质[M]. 北京:高等教育出版社, 2010:149-151 [4] Lovley D R, Coates J D, Blunt-harris E L, et al. Humic substances as electron acceptors for microbial respiration[J]. Nature, 1996, 382 (6590): 445-448 [5] Cervantes F J, De bok F A M, Tuan D D, et al. Reduction of humic substances by halorespiringsulphate-reducing and methanogenic microorganisms[J]. Environmental Microbiology, 2002, 4 (1): 51-57 [6] Coates J D, Chakraborty R, O'connor S M, et al. The geochemical effects of microbial humic substances reduction[J]. Acta Hydrochimica Et Hydrobiologica, 2000, 28 (7): 420-427 [7] Jiang J, Kappler A. Kinetics of microbial and chemical reduction of humic substances: Implications for electron shuttling[J]. Environmental Science & Technology, 2008, 42(10): 3563-3569 [8] Kappler A, Haderlein S B. Natural organic matter as reductant for chlorinated aliphatic pollutants[J]. Environmental Science & Technology, 2003, 37 (12): 2714-2719 [9] 向交,徐丽萍,李和平. 氧化还原电位的研究及应用[J]. 地球与环境,2014, (3):430-436 [10] Bohrerova Z,Stralkova R,Podesvova J,et al. The relationship between redox potential and nitrification under different sequences of crop rotations [J]. Soil & Tillage Research, 2004,77(1): 25-33 [11] Bruce W,Mizuba M M,Hansel C M.Iron promoted reduction of chromate by dissirnilatory iron-reducing bacteria[J].Environ Sci Technol,2001,35:522-527 [12] 杨钙仁,童成立,肖和艾,等. 水分控制下的湿地沉积物氧化还原电位及其对有机碳矿化的影响[J]. 环境科学,2009,30 (8) :2381-2386 [13] 徐志伟,腐殖质微生物还原的影响因素及其去除污染物的研究.杭州:浙江大学环境与资源学院硕士学位论文,2008 [14] 李丽,冉勇,盛国英,等,泥炭土连续碱抽提腐殖酸的分子结构特征[J].分析化学告,2001,30 (11):1303-1307 [15] 姜杰,李黎,孙国新. 基于三维荧光光谱特征研究土壤腐殖质氧化还原特性[J]. 环境化学,2012,31(12):2002-2007 -
点击查看大图
计量
- 文章访问数: 1844
- HTML全文浏览数: 1725
- PDF下载数: 1392
- 施引文献: 0
下载:
