共查询到19条相似文献，搜索用时 375 毫秒
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根据可变电荷和永久电荷共存的土壤体系的模式,研究了一个砖红壤和一个红壤胶体的表面电荷特性。由于两种土壤胶体的矿物成分和铁铝氧化物的含量不同,砖红壤胶体的pH。值、ZPNC和IEP都高于红壤胶体者。红壤胶体的永久负电荷量多,其pH0与ZPNC的差值也大。土壤加3%的有机质淹水培育4个月后,胶体的腐殖质含量增加不足0.5%,对胶体的pH0的影响不明显。砖红壤胶体用磷酸盐或硅酸盐处理后,表面正电荷减少,负电荷增多,pH0值和IEP都降低。磷酸盐的效应较硅酸盐为甚。不同浓度的KCl溶液中存在少量SO42-时,砖红壤胶体的正电荷减少,负电荷增加,ZPNC和pH0值降低;如存在少量Ca2+,则pH0值升高。以单一的K2SO4、为支持电解质时,pH0值较KCl者为高。 相似文献
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本文讨论我国几种主要土壤胶体的NH4+吸附特征。土壤胶体对NH4+的吸附符合两种表面Langmuir方程。土壤胶体对NH4+的结合能力强弱顺序是:黄棕壤>黑土、(土娄)土>红壤>砖红壤,而NH4+的解吸率大小顺序与此相反。Langmuir吸附方程参数K1与土壤胶体的粘粒矿物组成有关,并与土壤胶体对NH4+的相对偏好性(A值)呈正相关。Langmuir参数(M1+M2)与土壤胶体的CEC呈正相关,去有机质(OM.)前后△K1与△OM.呈反相关。去有机质可增加土壤胶体对NH4+的偏好性。土壤胶体的NH4+吸附和解吸特征决定于其组成和表面性质,并受有机无机复合作用的影响。永久电荷吸附位对NH4+的偏好性较强,而可变电荷吸附位则较弱。 相似文献
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本文研究了土壤中可变电荷表面磷的解吸特性。结果表明,磷解吸量与吸附量成正相关,并与直线方程和指数方程拟合。其平均解吸百分数依次为:高岭石(66%)>无定形硅酸铝(60%)>砖红壤粘粒(55%)>>无定形氧化铁(29%)>三水铝石(23%)>>火山灰粘粒(9%)。解吸体系的pH是借对磷酸根质子的解离和表面电荷的影响而制约解吸量。F-和OH-离子对磷酸盐化的三水铝石连续解吸的结果表明,磷酸根和氟离子在三水铝石表面的吸附量或剩余量之和均较为接近,这揭示了H2PO4-和F-离子之间既竞争又相互补充表面空位。它可作为一种区分磷吸附形态和沉淀的定量方法来进一步研究。 相似文献
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本文研究了理化性质不同的黄棕壤、红壤和砖红壤对Zn、Ni、Co的竞争吸附。采用含有不同重金属离子量的0.05molL1Ca(NO3)2溶液平衡,pH为5.5。结果表明,其吸附量的顺序:黄棕壤>砖红壤>红壤。对各离子的选择性为:Zn>Ni≥Co。竞争吸附的机制与非竞争吸附有明显的不同。其特征首先表现在吸附量上,竞争吸附要比非竞争吸附高得多。特别明显的,土壤去掉游离氧化铁后其吸附量不但不降,反而有不同程度的增加,Zn2+表现尤为突出;影响吸附量很大的陪伴阴离子作用受到严重抑制;反映土壤与重金属离子间作用能力大小的pH50的变化符合吸附等温线的特点。其次根据土壤对重金属离子的吸附和解吸的情况,可以认为,红壤胶体表面吸附位数量远不及黄棕壤和砖红壤,但高能吸附位的比例高。 相似文献
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本文研究了氧化物对红壤、高岭土和合成无定形铝硅酸盐的电荷零点的影响,并讨论了土壤中水合氧化物型表面的区分。结果表明,水合氧化物型表面可进一步区分为电荷性质完全不同的两类亚表面。在所研究的土壤和粘土样本中,有高ZPC的氧化铁(Fe-OH)和氧化铝(Al-OH)表面,是带可变正电荷的亚表面,使样本的ZPC趋于上升;而有低ZPC的氧化硅(Si-OH)表面,是带可变负电荷的亚表面,使样本的ZPC趋于下降。合成无定形铝硅酸盐的电荷零点与样本的Al2O3/Si2,摩尔比呈显著的正相关。 相似文献
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土壤胶体中氧化物表面性质的初步研究 总被引：1，自引：0，他引：1
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。 相似文献
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蚯蚓粪的NH4+吸附等温线与DTA曲线特征 总被引：2，自引：1，他引：2
本文研究了南宁三种饲料人工饲养的蚯蚓的蚯蚓粪(简称蚓粪)对NH4+的吸附等温线,并与武功的蚓粪作比较。蚓粪对NH4+的吸附一般大于土壤对NH4+的吸附,南宁蚓粪又大于武功蚓粪。蚓粪吸附NH4+量的多少与其中有机质含量有关,特别与其中中温放热反应的有机质(即易于分解的有机质)呈正相关。不同饲料组成对蚓粪吸NH4+等温线的参数影响不同。在Langmuir方程中与结合能常数有关的K值的次序为:纯牛粪>牛粪+烂橙果>牛粪+草菇培养基脚料而与最大吸附量有关的M值的次序为:牛粪+烂橙果>纯牛粪>牛粪+草菇培养基脚料而以K与真M的总的效应表示的b值的次序为:纯牛粪>牛粪+烂橙果>牛粪+草菇培养基脚料因此,牛粪不仅是一个良好的蚯蚓饲料,并且可使蚓粪具有良好的保NH4+力,成为一种有效的吸附剂。 相似文献
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本文研究了中南地区不同纬度带花岗岩母质发育的黄棕壤、红壤、砖红壤的胶体表面性质与粘土矿物组合、14×10-10m矿物、氧化物的关系。结果表明:(1)黄棕壤、红壤、砖红壤粘粒的阳离子交换量、比表面和内表面占总表面的比例依次减小,这与其高岭石、粘粒氧化物含量依次增加,14×10-10m矿物含量依次减少有关,且也与14×10-10m矿物在黄棕壤中主要是蛭石,在红壤中主要是14×10-10m过渡矿物,砖红壤不含14×10-10m矿物的结论相符合。(2)在其他矿物类型和含量相近下,14×l0-10m矿物是蛭石的土壤与14×10-10m矿物是14×10-10m过渡矿物的土壤相比,前者的阳离子交换量、比表面、内表面占总表面的比例比后者高些,但土壤的活性酸度弱些,交换性铝含量比后者低些。 相似文献
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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. 相似文献
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Three Oxisols, developed from serpentinite (Sungai Mas Series), basalt (Kuantan Series) and andesite (Segamat Series), selected to represent the most common Oxisols in Malaysia were sampled and studied. The objectives of this study were: (i) to determine mineralogical composition and factors responsible for changes in point of zero charge (pH0) of the variable charge component of three Oxisols; (ii) to use pH0 values to assess degree of chemical weathering; and (iii) to determine the magnitude of variable charge using corrected back-titration technique. The mineralogical composition was determined by X-ray diffraction analysis (XRD). The pH0 was determined by potentiometric titration in different electrolyte strengths. The magnitude of variable charge generation as a function of soil pH was measured using corrected back-titration to allow elimination of charge overestimation caused by solid dissolution and hydrolysis reactions. The results showed that the mineralogical composition were similar (kaolinite, goethite, hematite and gibbsite) between profiles but different in proportion, except for gibbsite which was absent in the andesite-derived soil. The sequential removal of soil organic matter (SOM), iron oxides and SOM together with iron oxides resulted in the changes of pH0 from 3.9–5.7 to 5.3–6.7, 2.6–3.7 and 3.3–4.5, respectively. These pH0 changes indicate SOM and sesquioxides are masking mineral surfaces and are factors responsible for lowering and increasing pH0 values, respectively. Regression correlation (R2 = 0.87??) showed that for every 1% organic C may decrease 1.0 unit of pH0 value. The pH0 values, after SOM removal, are in the order of Sungai Mas ～ Segamat > Kuantan Series. This suggests that the serpentinite and andesite-derived soils have achieved a relatively similar degree of chemical weathering and they are more weathered than the basalt-derived soil. The charge measured by corrected back-titration is 1.5–3.8 cmolc kg? 1 at pH 4.5 and increases to 4.2–10.8 cmolc kg? 1 at pH 6.5, indicating that the three Oxisols mainly bear variable charge. Charge overestimation resulted from dissolution and hydrolysis reactions during potentiometric titration ranges from 36 to 160%, depending on pH values (the lower the pH the higher is the overestimation). Hence, back-titration is a reliable technique to correct charge overestimation when using the traditional potentiometric titration for highly weathered tropical soils. 相似文献
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恒电荷土壤胶体对Cu2+ 、Pb2+ 的静电吸附与专性吸附特征 总被引：23，自引：2，他引：23
供试土壤胶体对Cu2 、Pb2 的吸附强度用pH50 值表示 ,其大小次序为 :土 >黄绵土、黑垆土 >黄褐土。离子强度实验和表面络合反应机制证明恒电荷土壤胶体对Cu2 、Pb2 的吸附含有专性吸附 ,n值可作为判断专性吸附与静电吸附比例的特征值 ,低pH值时 ,以水解 -络合吸附为主 ;高pH值时 ,以水解 -络合与沉淀吸附为主。静电吸附和专性吸附的比例与pH有关 ,各土壤胶体专性吸附百分数大小为 :黄褐土 >土 >黑垆土 >黄绵土。不同土壤胶体在同一介质中对Cu2 、Pb2 的固有络合常数logKintM 值及固有络合ΔG m 负值大小次序与吸附强度大小一致。在定pH定浓条件下 ,考虑离子之间的相互作用时 ,土壤胶体对重金属离子的吸附过程可用BDM等温式描述。供试土壤胶体对Cu2 、Pb2 专性吸附ΔG m 的大小与固有络合ΔG m 接近且大小次序也一致。 相似文献
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土壤磷酸盐位是研究土壤磷有效度的具有相对能量意义的概念,它的提出为研究土壤磷的问题开辟了一条新的途径[2,3,11].磷位值是土壤有效磷的强度指标,把它运用于土壤需磷诊断上,使它成为指导磷肥施用的有用工具,在当前生产上有一定意义. 相似文献
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The pH0 and ZPC of two Hydiandepts were determined by potentiomettic titiation in NaCl and by ion adsorption measurements from NH4NO3, respectively. The decrease of pH, pH0, and ZPC due to drying was explained by the hydrolysis reaction. Partial drying, high organic matter content, and low Al2 O3 concentration in the surface soil were responsible for its low pH, pH0 and ZPC. The high pH0 of subsoils was attributed to the presence of amorphous aluminosilicates and mixed polymeric gels of Fe(III) and A1 with high water content. The significant decrease of nitrate adsorption due to dehydration is discussed in relation to the change in pH, pH0, ZPC, and surface area on drying. 相似文献
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Pantelis E. Barouchas Nicholas Moustakas Aglaia Liopa-Tsakalidi 《Archives of Agronomy and Soil Science》2013,59(2):317-325
The lime requirement (LR) in 39 surface acid soil samples (0–30 cm) from western Greece was calculated using a single-addition titration of successive 3-mL 0.022 M calcium hydroxide [Ca(OH)2]. Soil pH measurements and titrations were performed in soil/water (1:2) and in a soil/0.01 M CaCl2 (1:2) suspension while being stirred. The results were referred to as ‘pH data group I’ and ‘pH data group II’, respectively. In each ‘pH data group’, the samples were separated into ‘pH data subgroups’, according to the total volume (mL) of 0.022 M Ca(OH)2 added to increase the initial pH (pHa) to a target value of 6.5 (pHt). The fitted linear regression equation pHt = b × volume + pHa was used for each ‘pH data group’ to determine the slope b. The b-weighted mean for each ‘pH data group’ was calculated. The LR was then calculated as follows: Mg CaCO3 ha?1 = 0.495 (pHt – pHa)/b, where b is the average weighted mean from the two ‘pH data groups’ and is equal to 0.227. The validity of the above equation was confirmed after incubation with Ca(OH)2 for 72 h. This procedure is simple and gives a rapid and accurate estimation of LR with respect to the environment. 相似文献
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几种氧化铁的离子吸附特性研究 总被引：3，自引：1，他引：3
氧化铁是土壤中常见的氧化物,其中较为普遍的是针铁矿和赤铁矿,在某些土壤中也含有纤铁矿和无定形氧化铁.它们通常以极小的颗粒单独存在,或以胶膜状包裹在其它矿物颗粒的外面,有较大的比表面积,易受环境的影响,因此具有较高的活性,并对许多土壤的物理化学性质产生重要的影响.某些重金属离子和某些污染物进入土壤后的动向和行为也深受土壤中氧化铁的影响. 相似文献
18.
《Communications in Soil Science and Plant Analysis》2012,43(16):2079-2094
A pot experiment was conducted to study the influence of liming on changes in different forms of acidity in relation to soil properties. Thirty-six surface (0–15 cm deep) soil samples were collected from different soil orders, namely Entisols, Inceptisols, Alfisols, and Entisols of coastal saline zone of West Bengal, India, and incubated for 21 days with three doses of lime [i.e., no lime (L0), half lime (L1/2), and full lime (L1)]. Results of analysis of soil showed that there were significant increases in pH in water (pHw) and pH in 0.02 M calcium chloride (CaCl2) (pHCa) (1.3 and 1.5 units) and decrease in total acidity, hydrolytic acidity, exchange acidity, electrostatically bound aluminium (EBAl3+), and electrostatically bound hydrogen (EBH+) upon liming being from 1.53 to 0.57, 1.40 to 0.54, 0.13 to 0.03, 0.08 to 0.01, and 0.06 to 0.02 cmol (p+) kg?1, respectively. The decrease in values of all the forms of acidity was greater in L1 than in L1/2 treatment under Entisols of the terai zone, followed by Entisols of coastal saline zone, Inceptisols, and Alfisols. The forms of acidity showed significant positive correlation with each other but negative correlation with pHw and pHCa, except for EBH+. 相似文献
19.
Sibylle Pagel-Wieder Jürgen Niemeyer Frank Gessler 《Soil biology & biochemistry》2007,39(12):3034-3042
The adsorption of the insecticidal Cry1Ab protein of Bacillus thuringiensis (Bt) on Na-montmorillonite (M-Na) and soil clay fractions was studied. The aim of this study was not to find the adsorption capacity of the soils from the experimental field site, where Bt corn (MON810) was cultivated, but rather to characterize the adsorption behavior of the Cry1Ab protein at concentrations typically found at experimental field sites. In kinetic experiments, the Cry1Ab protein adsorbed rapidly (<60 min) on M-Na. As the concentration of M-Na was varied and the added Cry1Ab protein concentration was kept constant (20 and 45 ng ml−1), the adsorption per unit weight of Cry1Ab protein decreased with increasing concentrations of M-Na. Adsorption of Cry1Ab protein on M-Na decreased as the pH value of the suspension increased. All adsorption isotherms could be described mathematically by a linear regression with the parameter k, the distribution coefficient, being the slope of the regression line. Although their mineralogical composition was nearly identical, the soil clay fractions showed different k values. The different k values were correlated with the physical and chemical properties of the soil clay fractions, such as the organic carbon content, the specific external surface area, and the electrokinetic charge of the external surfaces of the clays, as well as with the external surface charge density. An increase in the amount of soil organic matter, as well as an increase in the electrokinetic external surface charge of the soil clays, decreased the distribution coefficient k. An increase of the specific external surface areas of the soil clays resulted in a higher distribution coefficient k.Less than 10% of adsorbed Cry1Ab protein was reversibly adsorbed on the soil clays and, thus, desorbed. The desorption efficiency of distilled water was higher than that of a solution of CaCl2 (2.25 mmol) and of dissolved organic carbon (50 mg C l−1). 相似文献