中南地区几种土壤的表面电荷特性Ⅲ.土壤的电荷量,电荷零点(PZC)和净电荷零点(PZNC)

研究了中南地区3种土壤的电荷量、电荷零点(PZC)和净电荷零点(PZNC)等表面电荷性质及其与土壤矿质组成的关系.结果表明:(1)从赤红壤、红壤到黄棕壤,永久负电荷量(CECp)趋于增大,主要与土壤的粘土矿物组成和粘粒含量有关;可变负电荷量(CECv)变异趋势不明显,主要与土壤氧化铁铝的组成及含量有关;可变负电荷量占负电荷总量的比例趋于降低;正电荷量趋于减小.(2)供试赤红壤、红壤和黄棕壤的PZC分别为3.90、3.35～3.50和2.96～3.12;赤红壤和红壤的PZNC分别为3.85和2.15～2.84,黄棕壤不存在PZNC.(3)初步提出可变电荷土壤表面电荷性质的指标为:PZC>3.0、PZNC>2.0、PZC朠ZNC<1.0和CECv/CEC8.2>0.4.     

SURFACE CHARGE CHARACTERISTICS OF SOILS IN CENTRAL AND SOUTHERN CHINA

研究了中南地区3种土壤的电荷量、电荷零点（PZC）和净电荷零点（PZNC）等表面电荷性质及其与土壤矿质组成的关系。结果表明（1）从赤红壤、红壤到黄棕壤,永久负电荷量（CECp）趋于增大,主要与土壤的粘土矿物组成和粘粒含量有关;可变负电荷量（CECv）变异趋势不明显,主要与土壤氧化铁铝的组成及含量有关;可变负电荷量占负电荷总量的比例趋于降低;正电荷量趋于减小。（2）供试赤红壤、红壤和黄棕壤的PZC分别为3.90、3.35～3.50和2.96～3.12;赤红壤和红壤的PZNC分别为3.85和2.15～2.84,黄棕壤不存在PZNC。（3）初步提出可变电荷土壤表面电荷性质的指标为PZC>3.0、PZNC>2.0、PZC朠ZNC<1.0和CECv/CEC8.2>0.4。     

胶体悬液中白云母与铁铝氧化物表面双电层的相互作用

白云母是一种原生矿物,也是土壤中常见的层状硅酸盐矿物,其负电荷主要由四面体结构中的Al置换Si而来[1]。在通常的pH条件下,白云母带负电荷,可变电荷土壤中的铁、铝氧化物带正电荷。当白云母与铁、铝氧化物存在于同一悬液     

电位滴定法研究可变电荷土壤表面酸碱性质的进展

我国长江以南地区的土壤富含铁铝氧化物,其土壤胶体表面电荷具有可变性,显著不同于温带地区的恒电荷土壤,因而称之为可变电荷土壤。开展可变电荷土壤的表面特性研究对农业可持续发展、土壤资源保护等均具有重要的现实意义。电位滴定法是开展可变电荷土壤表面特性研究最直接有效的方法。本文首先总结了电位滴定法的实验条件设置对可变电荷土壤表观电荷零点的影响,在此基础上,归纳了应用电位滴定法结合表面络合模型开展可变电荷土壤酸碱特性的研究进展,分类讨论了黏土矿物组成、氧化物、有机质等相关影响因子对可变电荷土壤酸碱缓冲能力的影响,并展望可变电荷土壤表面酸碱缓冲能力的未来研究。本文将有助于初学者理解可变电荷土壤,呼吁更多学者关注可变电荷土壤的酸碱缓冲特性研究及其在土壤资源可持续利用中所起的重要作用。     

中南地区几种土壤的表面电荷特性 Ⅲ.土壤的电荷量,电荷零点(PZC)和净电荷零点(PZNC)

研究了中南地区３种土壤的电荷量,电荷零点和净电荷零点等表面电荷性质及其与土壤矿物组成的关系,结果表明：（１）从赤红壤,红壤到黄棕壤,永久负电荷量趋于增大,主要与土壤的粘土矿物组成和粘粒含量有关,可变负电荷量变异有明显,     

土壤表面电荷测定的两种方法之比较

用返滴定法和Mehlich法研究测定了我国不同地带土壤 (砖红壤、红壤、黄棕壤、暗棕壤、黑土 )无机胶体的表面电荷。结果表明 :( 1 )两者的测定结果有较大的差异 ,其主要的原因是返滴定法和Mehlich法分别基于不同的衡量标准 ,从不同的侧面反映了土壤表面的电荷性质 ;( 2 )返滴定法与Mehlich法各有其优点 ,但在具体的测定过程中都有些环节可能需要改进。     

邻苯二甲酸和水杨酸在可变电荷土壤中的吸附行为

研究了2种低分子量有机酸邻苯二甲酸和水杨酸在2种代表性可变电荷土壤红壤和砖红壤中的吸附行为。结果表明,可变电荷土壤对有机酸的吸附容量较大,对邻苯二甲酸的吸附亲和力大于对水杨酸的亲和力,在砖红壤中2种有机酸的吸附量大于在红壤中的,这与土壤的游离铁、铝氧化物的含量一致。土壤氧化铁在有机酸吸附中起着重要作用,粘土矿物如高岭石对有机酸的吸附量很小。有机酸的吸附涉及专性吸附和静电吸附2种机制,并以前者为主。当pH小于4.5时,pH的改变对有机酸的吸附影响不大;当pH大于4.5时,有机酸的吸附量随pH的增加而减小。     

可变电荷土壤中胶粒双电层的相互作用与阴阳离子同时吸附

可变电荷土壤是在热带和亚热带地区母岩经历强烈的风化和淋溶作用形成的,或者由火山灰母质发育形成的土壤。这类土壤中硅酸盐矿物以高岭石为主,并含有大量Fe/Al氧化物。因此,这类土壤颗粒表面既带负电荷,又带有一定量的正电荷[1]。Qafoku和Sumner[2]研究发现带净负电荷的硅酸盐矿物颗粒和带正电荷的铁铝氧化物颗粒之间的相互作用是这类土壤能同时通过静电作用吸附阳离子和阴离子的主要原因。当用Ca(NO3)2溶液对装有可变电荷土壤的土柱进行淋溶实验时,Ca2+和NO-3在2.5孔隙体积(PV)后才在淋出液中同时出现,表明溶液中Ca2+和NO3-同时被土壤吸附[3]。当用稀CsCl溶液(0.5mmo     

雷州半岛玄武岩发育土壤的表面电荷性质与土壤发育程度的关系

<正>热带、亚热带地区的可变电荷土壤由于遭受强烈的风化和淋溶作用并富含铁铝氧化物,其表面化学性质与温带地区的恒电荷土壤显著不同。其中最重要的差别在于这类土壤的表面电荷随着pH等环境条件的改变而变化[1]。过去对我国南方可变电荷土壤的表面电化学性质已开展了比较多的研     

土壤胶体中氧化物表面性质的初步研究

我们以蒙脱石为对照,测定了以水合氧化物型表面为主的试样四个方面的表面性质:电荷零点(ZPC)、滴定曲线、羟基释放量及不同pH条件下对NH₄⁺和Cl^-的吸附。结果表明,在pH 4—9范围内,氧化物型表面提供可变正电荷1—8 meq/100g,提供可变负电荷3—15meq/100g;三二氧化物使土壤的ZPC升高,而永久负电荷和有机质使土壤的ZPC降低。作为粘土酸,氧化物表面的酸性较弱,其表面质子逐步解离,使滴定曲线不出现突跃。氧化物表面的羟基和水合基密度很高,增加了土壤对离子的专性吸附能力。土壤中常见的氧化物型表面主要来自Fe,Al氧化物及非品质矿物,就它们的化学式而言,主要有Si—OH、Fe—OH及Al—OH,它们可存在于同一土壤中,在土壤常见的pH范围内,具有低ZPC的Si—OH亚表面提供可变负电荷,具有高ZPC的Fe—OH和Al—OH亚表面提供可变正电荷。     

Surface chemical properties and pedogenesis of tropical soils derived from basalts with different ages in Hainan,China

Limited information is available on the changes of surface chemical properties of tropical soils with time during the pedogenesis. Soil samples of three profiles derived from basalts of 10, 1330 and 2290 kilo annum (ka) in age were collected from adjacent locations in a tropical region of Hainan Province, China. The changes in soil surface chemical properties and the mineralogy of the soil clay fraction with time were investigated using ion adsorption, micro-electrophoresis, and X-ray diffraction analysis. The content of 2:1-type clay minerals decreased, while those of kaolinite and gibbsite increased with increasing basalt age and degree of soil development. The content of pedogenic free iron (Fe) oxides and the ratio of free Fe oxides/total Fe oxides increased with soil development stage, while soil poorly crystalline Fe and aluminum (Al) oxides had an opposite trend. The positive surface charge of the soils increased with increasing basalt age and degree of soil development; this was consistent with the change in their contents of free Fe/Al oxides. However, the value of negative surface charge had an opposite behavior. The soil derived from 10-ka-basalt had much more negative charge than soils derived from 1330- and 2290-ka-basalt. Soil net surface charge and zeta potential of the soil clay-fraction decreased with the increase in basalt age. Both net charge–pH curves and zeta potential–pH curves shifted to positive values with increased basalt age and degree of soil development. Increasing age also elevated the point of zero net charge of the soil and the isoelectric point of soil colloids.     

土壤电化学性质的研究Ⅲ.红壤胶体的电荷特征

土壤胶体的电荷性质,与土壤的一系列物理化学性质有密切关系。红壤的某些与肥力有关的物理化学性质,与其它类型土壤有所不同。例如,它的阳离子交换量较小,而阴离子吸附量则较大,分散性较弱,胀缩性也较小。红壤在物理化学性质方面的这些特点,大多是由其胶体的电荷特点所引起。     

可变电荷土壤中特殊化学现象及其微观机制的研究进展

综述了近年来可变电荷土壤化学研究的进展,着重总结了可变电荷土壤中的盐吸附、铁铝氧化物对土壤自然酸化的抑制作用和离子强度对离子专性吸附的影响等特殊化学现象及其微观机制的研究进展。用颗粒表面扩散层重叠导致有效电荷数量减小的原理解释了盐吸附现象和铁铝氧化物对土壤自然酸化的抑制作用。阐明了可变电荷土壤和矿物中介质离子强度影响离子专性吸附的机制,用四层吸附模型解释了离子专性吸附随离子强度增大而增加的现象,并根据胶体zeta电位随离子强度改变而变化的趋势进一步证明了离子强度增大使胶体专性吸附面上静电电位的绝对值减小,是离子专性吸附随离子强度增大而增加的主要原因。带电颗粒表面双电层结构和双电层相互作用的深入研究,有助于阐明可变电荷土壤中一些特殊化学现象的微观机理,从而进一步完善土壤化学理论。     

Composition and Characteristics of Organo—Mineral Complexes of Red Soils in South China

The objective of the present study is to reveal the composition and characteristics of organo-mineral complexes in red soils (red soil,lateritic red soil and latosol) of south China in terms of chemical dissolution and fractional peptization methos.In the combined humus,most of the extractable humus could dissolve in 0.1 M NaOH extractant and belonged to active humus (H1),and there was only a small amount of humus which could be further dissolved in 0.1 M Na4P2O7 extractant at pH 13 and was stably combined humus (H2).The H1/H2 ratio ranged from 3.3 to 33.8 in red soils,and the proportions of both H1 and total extractable organic carbon (H1 H2) in total soil organic carbon and the ratios of H1 to H2 and H1 to (H1 H2) were all higher in lateritic red soil and latosol than in red soil.The differences of combined humus composition in various red soils were directly related to the content of Fe and Al oxides.In organo-mineral complexes,the ratio of Na-dispersed fraction (G1) to Na-ground-dispersed fraction (G2) was generally smaller than 1 for red soils,but there was a higher G1/G2 ratio in red soil than in lateritic red soil and latosol.G1 fraction had a higher content of fulvic acid (FA),but G2 fraction had a higher content of humic acid (HA).The ratios of H1 to H2 and HA to FA were higher in G2 than in G1.The differences in the composition and activity of humus between G1 and G2 fractions were related to the content of free Fe and Al oxides.The quantities of complex Fe and Al,the Fe/C and Al/C atomic ratios were higher in G2 than in G1,and the ratio of Al/C was much higher than that of Fe/C.It may be deduced that aluminum plays a more important role than iron in the formation process of organo-mineral complexes in red soils.     

磷酸盐吸附对可变电荷土壤正负电荷的影响

本文研究了华南地区不同类型的可变电荷土壤，并对磷酸盐的吸附量和吸附磷后土壤的正、负电荷的变化，以及ｐＨ和游离氧化铁对这种变化的影响进行了研究。结果表明，土壤吸磷量与土壤游离氧化铁含量成良好的正相关。土壤吸磷后正电荷减少，负电荷增加，土壤电荷量与吸磷量之间呈抛物线状相关。吸附１摩尔磷酸盐对土壤净负电荷的贡献在０．３－１．０摩尔之间。土壤中的游离氧化铁使吸附的磷对土壤负电荷的贡献减少。     

Lability of soil organic carbon in tropical soils with different clay minerals

Soil organic carbon (SOC) storage and turnover is influenced by interactions between organic matter and the mineral soil fraction. However, the influence of clay content and type on SOC turnover rates remains unclear, particularly in tropical soils under natural vegetation. We examined the lability of SOC in tropical soils with contrasting clay mineralogy (kaolinite, smectite, allophane and Al-rich chlorite). Soil was sampled from A horizons at six sites in humid tropical areas of Ghana, Malaysian Borneo and the Solomon Islands and separated into fractions above and below 250 μm by wet sieving. Basal soil respiration rates were determined from bulk soils and soil fractions. Substrate induced respiration rates were determined from soil fractions. SOC lability was significantly influenced by clay mineralogy, but not by clay content when compared across contrasting clay minerals. The lability of SOC was lowest in the allophanic and chloritic soil, higher in the kaolinitic soils and highest in the smectitic soil. Our results contrast with conventional concepts of the greater capacity of smectite than of kaolinite to stabilize SOC. Contents of dithionite-citrate-bicarbonate extractable Fe and Al were inversely related to SOC lability when compared across soil types. A stronger inverse correlation between content of ammonium-oxalate extractable Fe and SOC lability was found when considering the kaolinitic soils only and we conclude that the content of active Fe (hydr-) oxides controls SOC stabilization in the kaolinitic soils. Our results suggest that the validity of predictive models of SOC turnover in tropical soils would be improved by the inclusion of soil types and contents of Fe and Al (hydr-) oxides.     

可变电荷土壤中铜离子的解吸

研究了我国四种可变电荷土壤红壤、赤红壤、砖红壤和铁质砖红壤以及二种恒电荷土壤黄棕壤和黑土中吸附性铜离子的解吸特征。研究结果表明 ,可变电荷土壤吸附的一部分铜离子可以被去离子水解吸 ,而且在pH～解吸率曲线上在一定pH值时出现解吸率最大值。在最大值时不同土壤中铜离子解吸率的大小与土壤中氧化铁的含量有关。氧化铁的含量越高 ,在最大值时铜离子的解吸率越大。当用中性电解质解吸可变电荷土壤吸附的铜离子时 ,电解质的浓度越大 ,解吸率越低。与此相反 ,恒电荷土壤吸附的铜离子不能被去离子水解吸 ,只能被中性电解质解吸 ,且电解质的浓度越高 ,解吸率越大。这表明 ,可变电荷土壤中吸附性铜离子的解吸规律 ,完全不同于恒电荷土壤中者。本文初步讨论了其原因     

Comparison of the surface chemical properties of four soils derived from Quaternary red earth as related to soil evolution

The surface chemical properties of soil samples i.e., surface charge and zeta potential, and the mineralogy of soil clay fraction were investigated with reference to soil weathering extent for four different soils derived from Quaternary red earth using the ion adsorption method, a micro-electrophoresis method and the X-ray diffraction analysis. Results indicated that all these soil samples contained kaolinite and gibbsite. The Ultisols from Guizhou, Hunan and Jiangxi possessed the 2:1 type clay minerals of mica and vermiculite. Hematite and magnetite were found in the Ultisols from Guangxi, Hunan and Jiangxi. Goethite was found in the Ultisols from Jiangxi, Hunan and Guizhou. The positive surface charge for these soils decreased with the order: the Ultisol from Guangxi ≅ the Ultisol from Guizhou > the Ultisols from Hunan and Jiangxi from south to north when pH < 5.0. This is consistent with the content of free Fe/Al oxides present in these soils. On the other hand, the value of negative surface charge on the Ultisol from Guangxi was found much lower than the other soils perhaps because of the intensive weathering of the soil. Both permanent and variable negative charges for the former were also lower than the latter, whereas the point of zero salt effect (PZSE) for the former was greater than that of the latter. The variability of soil negative surface charge followed the order: the Ultisol from Guangxi > the Ultisol from Guizhou > the Ultisol from Jiangxi ≅ the Ultisol from Hunan. The zeta potential and isoelectric point (IEP) of soil colloids and soil net surface charge followed the same order: the Ultisol from Guangxi > the Ultisol from Guizhou > the Ultisols from Hunan and Jiangxi. A good correlation between zeta potential and net surface charge of these soils was observed. Therefore, the magnitudes of the PZSE, IEP and zeta potential of these soils were in agreement with the weathering extent of the soils and can be employed as reference criteria for classification and evolution of soils.     

可变电荷土壤吸附铜离子时氢离子的释放

可变电荷土壤吸附铜离子后 ,土壤的中和曲线上不出现pH突跃 ,而变成一条平缓变化的曲线。当土壤悬液的pH低于一定数值时 ,加入铜离子后不释放氢离子。该pH值与土壤中氧化铁的含量有关。氧化铁的含量越高 ,该pH值越高。对于大多数可变电荷土壤 ,此pH值为 4左右。对可变电荷土壤 ,pH值越接近 4,氢离子释放的快速过程越不明显。在pH 4左右 ,加入铜离子后 1 0分钟时 ,释放的氢离子量仅占 6 5分钟时释放量的 3 0 %左右。但当pH值高于 4 5时 ,在大多数情况下 ,加入铜离子后半分钟时释放的氢离子量即可占 6 5分钟时的 5 0 %以上。恒电荷土壤吸附铜离子时氢离子的释放速度比可变电荷土壤快得多。即使pH值低至 3 8,在加入铜离子后半分钟时氢离子的释放量即占 6 5分钟时的 5 6 %以上。可变电荷土壤吸附铜离子时的H/Cu比比恒电荷土壤大得多。当恒电荷土壤悬液中加入0 1mo1L- 1 NaNO3作支持电解质时 ,吸附铜离子时的H/Cu比增大。