土壤电化学的建立与发展

虽然在土壤学中“电化学”这个名称由来已久，但文献中对土壤电化学的含义的认识却很不相同。６０ 年代初，我们分析了土壤化学的发展史和现状，也参考了电化学和胶体化学的发展情况，提出了土壤电化学的范畴是研究土壤中带电粒子间的相互作用及其化学表现。近４０ 年来的研究成果表明，关于土壤电化学的这个定义及其范畴是适当的。根据土壤化学的发展趋势和我国土壤分布的特点，我们从水稻土的物理化学、可变电荷土壤的电化学和土壤电分析化学等方面的研究，发展土壤电化学。经过几十年的努力，我国已基本建立起较完整的土壤电化学体系，有关的研究成果对促进我国土壤科学的发展及提高我国土壤学的国际地位作出了积极的贡献。但是，我国的土壤电化学仅仅走过了开创阶段，真正的理论上的突破则有待于今后的努力。除了学科本身的发展以外，土壤电化学的实际应用也应是逐渐开拓的一个重要方面。有理由相信。

加强土壤电化学研究 占领土壤科学前沿

加强土壤电化学研究 占领土壤科学前沿于天仁，季国亮（中国科学院南京土壤研究所）一、意义各种自然体都有其宏观的方面和微观的方面，自然科学发展到现在，有的学科向宏观的方面发展，但更多的学科着重向微观的方面发展。例如，物理学中的焦点是基本粒子，化学中发展了...

中国土壤电化学的发展历程

本文介绍了土壤电化学研究历时50多年的系统成果,涉及带电粒子的化学行为、电极使用、学科渗透、工作成就、国内外影响和评价,形成集基本理论、实际应用和研究方法于一体的土壤电化学体系。在近期继承发展上,论述了电化学体系的土壤氧化还原过程及其研究法和酸化红壤修复原理与技术。前者扼要说明红壤中铝、锰离子的非等当量交换和非电性吸附;地跨湿润至干旱地区土壤氧化还原状况的水平带谱、垂直分异;有机还原性物质和无机氧化性物质的依存关系和变化规律,从而论证氧化还原过程作为土壤物质循环的转化动力(化学和生物学的)所作的贡献。后者扼要说明以铝化学为核心,土壤酸化理论、改良措施和从环保出发的工农业废弃物的利用;相反电荷胶体表面双电层的相互作用与电荷密度、离子强度、盐吸附的关系,扩散层重叠机制以及双电层作用对土壤表面性质和土壤酸化的影响。

环境化学中的土壤电化学问题

土壤电化学与环境化学 长期以来,土壤化学研究中的传统的着眼点是土壤的化学性质与植物生长的关系。但是近年来随着环境污染的日趋严重,促使土壤化学的研究对象有了明显的转移。以下举几个例子。环境污染对土壤化学研究方向的影响在日本反映得最早。从五十年代起,日本土壤学文献中有关重金属污染者大量出现。现在,在日本土壤学会之下,已有一个环境保护专业委员会与另几个专业委员会(如物理、肥力)并存。

关于土壤电化学未来发展的初步设想

文章从土壤学—土壤圈学乃至圈态学的角度,阐述了土壤电化学的特点和未来发展趋势。并提出了具体的研究课题。

土壤电化学

土壤电化学是研究土壤中带电粒子之间的相互作用及其化学表现的科学。这些带电粒子包括胶粒、离子、质子和电子。土壤电化学是土壤科学中的一个学科分支。它可以揭示土壤中的化学现象的本质,为土壤的合理利用和改良以及环境保护等提供科学依据。

土壤电化学研究取得新进展

土壤电化学是土壤学中一个新的基础性学科分支。它在土壤学从宏观到微观的发展过程中正处于最新阶段,而且它本身也在迅速发展之中。在国家自然科学基金的大力支持下,中国科学院院士于天仁教授主持了土壤电化学研究。根据土壤学的发展趋势和我国土壤的特点,该研究从水稻土的物理化学性质、可变电荷土壤(红壤)的电化学性质和土壤电化学方法3方面的研究发展土壤电化学,并取得了可喜的进展。

土壤微生物电化学系统降解四环素的机理

以四环素为研究对象,构建土壤微生物电化学系统(SMES),避光恒温培养58d后进行采样分析,研究了四环素降解、土壤理化性质、酶活性和三域微生物之间的内在联系,以揭示四环素在SMES中的生物降解机理.结果表明,采用SMES处理后,四环素降解率从52%显著提升至70%.与对照处理相比,脱氢酶活性在SMES中显著提升了144%,且与四环素降解率显著正相关.相比之下,在SMES中多酚氧化酶、过氧化氢酶和漆酶对四环素的降解效果微弱.pH值是影响土壤微生物群落的重要理化因子,且与四环素降解呈负相关关系.Network关联分析显示,真菌在四环素降解中起到关键作用,Geoalkalibacter、Microascus、Wardomyces和Scopulariopsis是四环素的潜在降解菌,其中Microascus和Scopulariopsis是脱氢酶的潜在分泌菌.

喀斯特生态系统土壤表面电化学特征及其影响因子

以西南喀斯特典型石漠化生态系统土壤为研究对象,采用空间替代时间的方法,研究石漠化演替过程中土壤表面电化学特征演变规律及其与土壤理化性质的相关性。采用物质表面联合分析法对不同石漠化等级土壤表面电化学属性进行测定。结果表明,土壤表面电荷密度、表面电场强度、比表面、表面电荷数量随石漠化强度的增加而下降,其变化范围分别为0.34 C·m^(-2)~0.42 C·m^(-2)、4.85×10^(8)V·m^(-1)~5.86×10^(8)V·m^(-1)、47.11 m^(2)·g^(-1)~53.16 m^(2)·g^(-1)、16.86 cmol·kg^(-1)~22.82 cmol·kg^(-1),土壤表面电位随石漠化强度的增加而上升,其变化范围为-113.74 mV~-115.10 mV;研究区黏土矿物组成为伊利石、高岭石、绿泥石、伊蒙混层、绿蒙混层,且以绿蒙混层为主;土壤黏粒、砂粒、非晶质氧化铝、胡敏酸是影响喀斯特石漠化地区土壤表面电化学属性变化的主要因素,解释率分别为48.3%、38.1%、13.0%、12.0%;土壤粒径组成、有机质组分和金属氧化物对土壤表面电化学特征影响由强到弱依次分别为:土壤黏粒>砂粒>粉粒,胡敏酸>有机碳>富里酸,非晶质氧化铝>游离氧化铁>非晶质氧化铁。本研究对中国西南喀斯特石漠化土壤管理与调控、退化植被恢复重建具有重要意义。

水平碳纤维刷耦合生物电化学系统强化土壤中总石油烃降解及扩展作用半径

为解决传统管状土壤生物电化学系统(SBES)应用中因土壤传质效率低导致的修复半径有限的问题,借助水平定向钻机设备构建了水平碳纤维刷耦合SBES的新构型,通过搭建水平电子通路促进远端石油污染物降解,探究水平碳纤维刷SBES构型对土壤总石油烃(TPH)降解的最大作用半径。结果表明:在启动80 d后,水平碳纤维刷SBESs构型的TPH去除率可达到46.4%~49.0%,比垂直SBES提高了169.8%~184.9%,相较于自然降解处理组提高了358.4%~385%,微生物输出的最大电流密度达到21.7~35.8 mA/m^(2)。水平碳纤维刷耦合SBESs构型的最大作用半径为136~138 cm,是垂直SBES的1.48~1.50倍。综上,水平碳纤维刷耦合SBES强化了微生物石油烃降解及扩展了作用半径,可为SBES在工程应用领域提供全新的解决方案。

土壤中的电腐蚀

电腐蚀是杂散电流腐蚀的简称。杂散电流是指非固定通路上流动的电流。它可分直流杂散电流和交流杂散电流。这些电流通过埋地金属构件产生的腐蚀作用称为土壤杂散电流腐蚀或干扰腐蚀,即土壤中的电腐蚀。例如在直流电气化铁路附近的地下管道、储罐、钢桩。

土壤腐蚀机理及研究技术的发展

本文综述了微电池和宏电沲这两种腐蚀形式的发生，作用，土壤腐蚀形成的转化及其影响因素，同时还初步论述了土壤腐蚀研究技术的新发展。

土壤电修复技术研究进展

介绍了土壤电修复技术的最新研究进展,讨论了其在技术原理、过程建模和应用工艺等方面的研究现状。说明了电修复技术是近年来得到广泛重视的一种新型土壤修复技术,可显著强化土壤中的传质过程。特别指出的是,电修复技术可与其他土壤修复技术,如生物修复等直接耦合,发展出能效更高的复合修复技术。

测量模拟土体zeta电位的简易流动电位装置及其使用方法

本文展示了一款可应用于土壤学领域研究的简易流动电位测量装置。为验证该装置的可行性,采用石英砂和包铁石英砂模拟土体所具有的多孔结构和表面电荷特征,基于流动电位法测量了石英砂在不同浓度(0.01、0.05、0.1、0.5、1.0、2.0和5.0 mmol·L^(-1))NaCl溶液中的zeta电位和石英砂与包铁石英砂在不同pH(4.4、5.2、6.1、6.6、6.9、7.7和8.0)电解质溶液中的zeta电位。同时采用电泳法测量了石英砂胶体在不同pH电解质溶液的zeta电位以作比较。结果表明:在考虑表面电导时,流动电位法测得石英砂在不同浓度NaCl溶液中的zeta电位随溶液浓度的升高逐渐往正值方向移动。这是由于随着离子强度增加,石英砂的双电层厚度受到压缩,zeta电位的绝对值逐渐降低;相同离子强度下,随溶液pH升高,石英砂和包铁石英砂表面官能团发生去质子化作用,流动电位法测得石英砂和包铁石英砂的zeta电位均随pH升高而逐渐降低;由于电荷屏蔽作用,在带负电荷的石英砂表面包被带正电荷的氢氧化铁后,流动电位法测得包铁石英砂的等电点pH(IEP)介于石英砂和氢氧化铁的IEP。此外,流动电位法测得的石英砂颗粒在不同pH电解质溶液中的zeta电位与电泳法测得的石英砂胶体在不同pH电解质溶液中的zeta电位具有较好的一致性。可见采用自制流动电位装置所获结果均与理论预测及常规电泳法测定结果相符,准确度较高。自制流动电位装置结构简单、操作方便、加工制造容易。该装置可被土壤学领域的研究者借鉴参考,以望为土壤电化学研究工作做出贡献。

Electrical Conductivity in Soil Extracts: Chemical Factors and Their Intensity

The electrical conductivity （EC） of 1：5 soil-water extract （EC1：5） was studied utilizing path coefficient analysis. The study focused on revealing the main chemical factors contributing to EC of soil extracts and their relative importance. Results showed that the most important factors influencing the EC1：5 of coastal salt-affected soils were the concentration of salt in 1：5 soil-water extract （So）, Cl^-, and the sodium adsorption ratio （SAR）, while effects of pH, CO3^2-, HCO3^, soluble sodium percentage （SSP）, and sodium dianion ratio （SDR） were very weak. Though the direct path coefficients between EC1：5 and SO4^2- , Ca^2＋, Mg^2＋, K^＋, or Na^＋ were not high, influence of other chemical factors caused the coefficients to increase, making the summation of their direct and indirect path coefficients relatively high. Evidences showed that multiple regression relations between EC1：5 and most of the primary factors （So, Cl^-, and SAR） had sound reliability and very good accuracy.

Point of Zero Salt Effect: Relationships with Clay Mineralogy of Representative Soils of the So Paulo State, Brazil

The point of zero salt effect （PZSE） is the soil pH value at which the magnitude of the variable surface charges is not changed due to variations in the ionic concentration of the soil solution. This property influences not only electrochemical phenomena occurring at the solid-solution interface but also the flocculation degree of the soil particles. In this study we investigated the relationships between the clay mineralogy and the PZSE values of representative soils of the Sāo Paulo State, Brazil. The results confirmed the usefulness of the difference between the soil pH values measured in 1 mol L^-1 KCl （pHKCl） and in water （pHH2O） （2 pHKCl-pHH2O） for estimating the PZSE of tropical soils, except for the ones rich in exchangeable Al; furthermore, the ApH index （pHKC1 - pHH2O） was highly correlated with the difference between the PZSE and pHH2O values, reiterating the △pH utility for estimating both the signal and the magnitude of the net surface charge of tropical soils. Finally, correlation and multiple regression analyses showed that the PZSE value of weathered non-allophanic tropical soils tends to increase and to equal the soil pH due to the weathering-induced kaolinite destabilization and concomitant Fe- and Al-oxide accumulation.

Relationship Between Iron Oxides and Surface Charge Characteristics in Soils

The relationship between iron oxides and surface charge characteristics in variable charge soils ( latosol and red earth ) was studied in following three ways. ( 1 ) Remove free iron oxides ( Fed ) and amorphous iron oxides ( Feo ) from the soils with sodium dithionite and acid ammonium oxalate solution respectively. ( 2 ) Add 2% glucose ( on the basis of air-dry soil weight ) to soils and incubate under submerged condition to activate iron oxides, and then the mixtures are dehydrated and air-dried to age iron oxides. ( 3 ) Precipitate various crystalline forms of iron oxides onto kaolinite. The results showed that free iron oxides ( Fed ) were the chief carrier of variable positive charges. Of which crystalline iron oxides ( Fed-Feo ) presented mainly as discrete particles in the soils and could only play a role of the carrier of positive charges, and did little influence on negative charges. Whereas the amorphous iron oxides ( Feo ) , which presented mainly as a coating with a large specific surface area, not only had positive charges, but also blocked the negative charge sites in soils. Submerged incubation activated iron oxides in the soils, and increased the amount of amorphous iron oxides and the degree of activation of iron oxide, which resulted in the increase of positive and negative charges of soils. Dehydration and air-dry aged iron oxides in soils and decreased the amount of amorphous iron oxides and the degree of activation of iron oxide, and also led to the decrease of positive and negative charges. Both the submerged incubation and the dehydration and air-dry had no significant influence on net charges. Precipitation of iron oxides onto kaolinite markedly increased positive charges and decreased negative charges. Amorphous iron oxide having a larger surface area contributed more positive charge sites and blocked more negative charge sites in kaolinite than crystalline goethite.

Study on Water－Soluble Organic Reducing Substances：Ⅲ．Electrochemical Properties of Decomposition Products of Rice Straw and Their Interactions with Variable Charge Soils

Some electrochemical properties,such as PH,Eh,and voltammetric behavior,of the decomposition products of rice straw and the in eractions of these products with soils were studied.The PH,Eh,and amounts of organic reducing substances changed markedly during the 60-day anaerobic decomposition.pH decreased sharply to pH 5 on the tenth day and then increased gradually to 7 on the 45th day.The amouats of organic reducing substances increased almost synchronously with the fall of redox potential during the first 15 days.The differential pulse voltammetric(dpv) behavior changed not only in the peak current but also in the peak potential.The fractions with apparent molecular weights lower than 200 dations appeared to be active in dpv behavior.The electric charge of organic reducing substances was closely related to the decomposition stage.The 6th day of incubation was the crucial time before and after which the major part of the components was negatively charged and positively charged, respectively.The group with a low apparent molecular weight and a negative charge was the main components responsible for the lower anodic peak potentials.They were oxidized first during the interactions of the organic reducing substances with soils.

Improvement of alkaline electrochemical characteristics of bauxite residue amendment with organic acid and gypsum

Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilitation.Mineral acids,citric acid and hybrid acid–gypsum additions were compared for their potential to transform and improve zeta potential,isoelectric point(IEP),surface protonation and active alkaline-OH groups,which are critical factors for further improvement of physicochemical and biological properties later.Isoelectric points of untransformed bauxite residue and six transformed derivatives were determined by using electroacoustic methods.Electrochemical characteristics were significantly improved by the amendments used,resulting in reduced IEP and-OH groups and decreased surface protonation for transformed residues.XRD results revealed that the primary alkaline minerals of cancrinite,calcite and grossular were transformed by the treatments.The treatments of citric acid and gypsum promoted the dissolution of cancrinite.From the SEM examination,citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of-OH groups on particle surfaces.The collective evidence suggested that citric acid and gypsum amendments may be used firstly to rapidly amend bauxite residues for alleviating the caustic conditions prior to the consideration of soil formation in bauxite residue.