用Wien效应研究土壤有机质对阳离子与黄棕壤型水稻土黏粒相互作用的影响

选择富含有机质的黄棕壤型水稻土,提取小于2μm的黏粒,将其中1/2黏粒去除有机质,分别制成为不同阳离子(Na+、K+、NH4+、Ca2+、Cd2+和La3+)饱和的土样,用Wien效应法研究土壤有机质对阳离子与土壤黏粒相互作用的影响。研究结果表明:原土悬液的起始电导率大于去有机质土者;除含Na+悬液外,去有机质土悬液的电导率随场强而增加的速率在50～100 kV cm-1以上,明显大于原土。有机质会使Na+以外的阳离子的平均结合自由能增大,Ca2+的结合能增加最大(增量为0.57 kJ mol-1),而Cd2+的结合能增加最小(增量为0.03 kJ mol-1)。对于供试土壤悬液,不同阳离子的结合能顺序均为Na+相似文献   

用悬液Wien效应研究Na+、K+、NH4+、Ca2+、Zn2+和Cd2+阳离子与红壤黏粒间的相互作用及能量关系

采用悬液Wien效应法研究了Na+、K+、NH4+、Ca2+、Zn2+和Cd2+阳离子与红壤黏粒间的相互作用及能量关系。结果表明,在试验条件下,红壤黏粒与阳离子Na+、K+、NH4+、Ca2+、Zn2+和Cd2+的平均结合自由能分别为:4.50、7.35、7.15、9.12、9.84和9.63 kJ mol-1。含Ca2+悬液的电导率随场强增加而递增最快,含Na+和NH4+悬液的电导率随场强增加而增加最慢,而含K+、Zn2+和Cd2+的悬液电导率的增速相近、介于其间。红壤悬液中不同阳离子的解离速率顺序为Ca2+>K+>Zn2+=Cd2+>Na+=NH4+。在低场强(15～80 kV cm-1)下,不同阳离子的平均吸附自由能ΔGad没有差异。在场强100 kV cm-1以上,二价阳离子的ΔGad明显大于单价阳离子,不同阳离子间ΔGad的大小顺序为NH4+≤Na+>K+=NH4+>Ca2+>Zn2+=Cd2+,Na+离子平均解离度的递增速率(场强增加1kV cm-1所引起的解离度增量)最大,为0.000 427 cm kV-1,其次是Ca2+离子,为0.000 221 cm kV-1,其余阳离子为0.000 12～0.000 14 cm kV-1。     

用离子活度法和悬液Wien效应法测定土壤对单价阳离子结合能的比较研究

选用黑土、黄棕壤、红壤和砖红壤黏粒与蒙脱土作供试样本,用离子活度法与悬液Wien效应法测定不同黏粒对单价阳离子Na+和K+的平均结合自由能。测试结果表明,对于黑土、黄棕壤和蒙脱土而言,用Wien效应法和离子活度法测定的钠离子的平均结合自由能ΔGbi比较一致,离子活度法相对于Wien效应法测定的钠离子平均自由结合能的相对误差在24%至10%之间;对于黑土和黄棕壤而言,用Wien效应法和离子活度法测定的钾离子平均结合自由能ΔGbi十分一致,相对误差在2%以下;对于红壤,相对误差为11.5%。结果还表明,钠玻璃电极应用于本试验条件下,仅当标准溶液与被测悬液的pH之差在0.5以下,才有测定意义;液膜钾电极在本试验条件下可用于测量土壤悬液中K+离子的活度,但在蒙脱土悬液中K+离子活度测量值偏大而不适用;到目前为止,还不能直接应用Wien效应法来测求带有正电荷的可变电荷土壤,如砖红壤,对单价阳离子的结合能。     

不同土壤对钾的选择吸附特性

用K Ca交换平衡法对砖红壤、红壤、土、黑土和水稻土K的选择吸附特性研究结果表明 :KG 和KV 系数随着K Ca平衡体系中吸附相中钾与钙比率的变化而改变 ,其曲线特征说明土壤胶体存在着对K亲和力不同的吸附点位。在低钾饱和度时 ,土壤对K的高选择吸附主要归于粘粒矿物楔形区域电荷点位吸附 ,五种土壤楔形区域相对吸附点位顺序为 :黑土 >土 >水稻土 >红壤 >砖红壤 ,该相对吸附点位顺序与土壤含有风化云母和蛭石有关。在高钾饱和度时 ,五种土壤对K的吸附主要发生于粘粒矿物的晶层表面电荷点位 ,粘粒矿物的晶层表面电荷起源也许起决定作用 ,此时KG 选择系数的大小顺序为 :砖红壤 >红壤 >黑土 >土 >水稻土     

有机质含量对棕壤表面电荷及NH4+的吸附解吸特性的影响

对棕壤在去除有机质前后表面电荷及NH4 的吸附解吸特性进行测定,结果表明:(1)去除有机质后,土壤胶体表面正电荷量增加,可变负电荷量减少,永久负电荷量增加。这可能是由于有机质带有大量的可变负电荷,掩蔽了一部分永久负电荷点位,同时中和了一部分土壤表面正电荷所致。(2)土壤对NH4 的吸附量和解吸量的变化与土壤表面电荷数量的变化呈现良好的一致性,有机质可以增加土壤对NH4 的吸附量,并降低其对NH4 的吸附结合能。土壤去除有机质后,其对NH4 的最大吸附量下降,吸附结合能增加,解吸率降低。     

不同pH下黄棕壤镉的吸附-解吸特征

对黄棕壤在pH2 7不同浓度下Cd2 的吸附与解吸进行了测定。结果表明,Cd2 吸附量随平衡液中Cd2 浓度增加而增大,两者关系较好地符合Langmuir吸附方程。根据吸附等温线参数与pH的相关方程,得到镉吸附等温线的pH依存模式,如Langmuir方程为:C/X=69 334e-1 7183pH (5 5793pH-3 0383)·C。式中,X为土壤Cd2 吸附量(mg/kg),C为平衡液中Cd2 之浓度(mg/L)。解吸Cd2 的数量随pH升高和吸附Cd2 的数量增加而增加,但解吸Cd2 占吸附Cd2 的比例随pH升高而降低,在pH3 7下,黄棕壤解吸Cd2 的比例为42%～95%,平均为75%,说明黄棕壤Cd2 以非专性吸附为主,吸附Cd2 的有效性高。     

有机质含量对棕壤表面电荷及NH4^＋的吸附解吸特性的影响

对棕壤在去除有机质前后表面电荷及NH4^＋的吸附解吸特性进行测定，结果表明：（1）去除有机质后，土壤胶体表面正电荷量增加，可变负电荷量减少，永久负电荷量增加。这可能是由于有机质带有大量的可变负电荷，掩蔽了一部分永久负电荷点位，同时中和了一部分土壤表面正电荷所致。（2）土壤对NH4^＋的吸附量和解吸量的变化与土壤表面电荷数量的变化呈现皇好的一致性，有机质可以增加土壤对NH4^＋的吸附量，并降低其对NH4^＋的吸附结合能。土壤去除有机质后，其对NH4^＋的最大吸附量下降，吸附结合能增加，解吸率降低。     

水化氯铝酸钙与传统钝化剂降低土壤镉生态及健康风险的对比研究

针对红壤、棕壤、褐土、黑土4种中国典型的Cd污染土壤,应用Ca(OH)2、Ca(H2PO4)2以及层状双金属氢氧化物（Layered Double Hydroxides,LDHs）、水化氯铝酸钙（CaAl-Cl LDH）开展钝化修复,并从土壤Cd的生态风险和健康风险角度进行修复效果对比研究。分析钝化剂对土壤pH值、土壤Cd的赋存形态以及土壤Cd直接经口摄入的生物可给性的影响,并对修复机理进行深入探究。结果表明,在Ca(OH)2、Ca(H2PO4)2和CaAl-Cl LDH各自相对最优施用量下,3种钝化剂均可显著降低土壤Cd的活性系数（P<0.05）,平均降幅分别为16.1%、56.9%和29.2%,可降低土壤Cd的作物吸收量及Cd对周边生态环境的风险。此外,施用CaAl-Cl LDH能显著且更为有效地降低土壤Cd的生物可给性（P<0.05）及Cd对人体的健康风险,在胃和小肠阶段的平均降幅为19.2%和33.0%,其中胃阶段分别达到施用Ca(OH)2和Ca(H2PO4)2的3.11和1.99倍,小肠阶段为5.99和2.72倍。该研究为Cd污染土壤钝化修复剂的开发、改进和选择提供了科学依据和参考。     

恒电荷土壤和可变电荷土壤动电性质的研究Ⅰ.阳离子吸附和pH的影响

本工作研究了阳离子吸附和pH对恒电荷土壤（黄棕壤、棕壤、暗棕壤和黑土）和可变电荷土壤（砖红壤）动电性质的影响。研究结果表明,砖红壤在不同溶液中的ζ电位随pH升高由正值变为负值,均有一个等电点（IEP）;pH>5时,在不同溶液之间砖红壤ζ电位的变化顺序为MnCl     

河南三种土壤阳离子交换量相关性及预测模型研究

土壤阳离子交换量是一项重要的土壤理化性质,它是衡量土壤肥力和作物养分有效性的一个重要指标。通过对河南3种土壤1177个数据的相关性及回归分析来研究阳离子交换量与土壤有机质、pH值、粘粒含量、粉粒含量和砂粒含量的关系。结果表明:(1)对于阳离子交换量来说,砂姜黑土>水稻土>褐土;3种土壤的上层土>下层土;3种土壤的阳离子交换量比第二次土壤普查分别降低15.7%,12.7%,6.5%;(2)对与砂姜黑土和褐土来说,其阳离子交换量与pH值和0.02~2 mm砂粒含量成显著负相关,褐土与粘粒含量成显著正相关;对于水稻土来说,其阳离子交换量与有机质含量和粘粒含量成显著正相关,与砂粒含量成显著负相关;(3)利用这些数据做出的这三个土壤类型的6个回归模型是有科学依据的。总的来说,土壤有机质、pH值、粘粒含量与砂粒含量与CEC有着紧密联系,但还有其他因素影响着预测模型的准确性。     

Solubility and standard Gibbs free energy of formation of natural imogolite at 25°c and 1 atm

We carried out a dissolution experiment to determine the solubility and the Gibbs free energy of formation of natural imogolite at 25°C and 1 atm. Purified gelatinous film of natural imogolite, synthetic gibbsite, and imogolite plus gibbsite were equilibrated in 1 mmol L^-1 HCI solutions and Si, Al concentrations and pH were monitored during 700 d. Imogolite plus gibbsite and gibbsite systems reached an equilibrium after 120 d. The logarithmic values of the equilibrium constants of dissolution reactions were 12.10±0.01 for imogolite and 8.01±0.01 for gibbsite. The calculated Gibbs free energy of formation was -2929.19±3.28 kJ mol^-1 for imogolite and -1155.11 ± 1.42 kJ mol^-1 for gibbsite. These values predict that the silicic acid concentration at the imogolite-gibbsite equilibrium would be 0.120 mmol L^-1.     

基于Mean shift的筛面物料颗粒目标运动轨迹跟踪

为了获取农业物料在风筛式清选筛面的实际运动规律,通过对多颗粒散体中的目标颗粒进行着色处理,提出采用基于颜色特征向量的Mean shift算法,实现对目标运动轨迹的跟踪。算法根据Bhattacharyya系数的大小判定跟踪目标是否被遮挡,并引入了Kalman滤波器设计。在正常跟踪过程中,利用Kalman滤波器预测每帧Mean shift算法的起始位置,然后利用Mean shift算法对目标进行精确定位,当目标被遮挡时,将其运动视为时不变系统,并通过Kalman滤波器估算目标近似位置。试验结果表明,该方法在复杂背景和光照变化条件下,实现了对快速运动目标的稳定持续跟踪,具有很好的鲁棒性,为散体颗粒运动规律的研究提供了一种图像检测方法。     

Long-term influence of different production systems on potassium buffering capacity of Typic Ustochrept soil

Imbalanced application of nutrients in the intensively cropped areas results in deterioration of soil fertility. Application of recommended dose of potassium (K) is essential for improving the use efficiency of other nutrients. To assess the buffering capacity of soil, three composite soil samples were collected from the surface soil (0–30?cm) during 2015 from 3 production systems viz., organic, inorganic and integrated which was maintained from 2004 with basmati rice–wheat–Sesbania system under Network Project on Organic Farming at ICAR-Indian Institute of Farming Systems Research, Modipuram. Fractionation of potassium (K) was achieved by sequential extraction of soil samples with distilled water, ammonium acetate and nitric acid in the same order. The relationship between the adsorbed and equilibrium potassium concentration, quantity was determined by plotting Freundlich adsorption isotherms. This was used to determine the buffering capacity and the concentration levels of potassium adsorbed on un-specific sites in the soil. The suitability of the adsorption equation was determined by applying the least square regression analysis. The results revealed that available potassium in the soils ranged from 119.51 to 135.01?mg/kg with 126.02?±?5.24?mg/kg as mean (ammonium acetate method) while water soluble and nitric acid extracted potassium ranged from 28.51 to 29.05?mg/kg and 2594.49?±?19.33?mg/kg (mean) in various production systems. The mean free energy of replacement was found to be ?1998.01?±?28.38?cal/mol indicating that soils have comparatively higher potassium supply under organic system. The potassium buffering capacity of the soils was found to be 0.7462?±?0.16?mg/kg, 0.6295?±?0.20?mg/kg and 0.6774?±?0.09?mg/kg in organic, integrated and inorganic systems, respectively. The amount of potassium adsorbed on un-specific sites of the organic, integrated and inorganic systems was found to be 7.4730?±?1.81, 15.11?±?2.40 and 11.6 89?±?3.58?mg/kg, respectively. It can be concluded that long-term organic production system improves K⁺ buffering capacity of Typic Ustochrept soil as compare to the integrated as well as inorganic production systems.     

黄芩分布区主要气候要素变化趋势时空特征分析

基于国内黄芩主要分布区确定的研究区内94个气象站点的气象观测数据,运用非参数统计检验Mann-Kendall、R/S等分析方法,分析了研究区1957-2007年气温、降水量和日照时数变化趋势的时空特征。结果表明：近50a来,研究区气温表现出显著的上升趋势,降水量、日照时数呈现出减少趋势,日照时数的变化趋势通过了0.01水平的显著性检验;Hurst指数分析表明,研究区未来气温、日照时数都表现出很强的持续性,即与过去近50a的变化趋势基本保持一致,降水量在东北段的减少持续性很强,华北段和西北段变化的持续性相对较弱;研究区气温、降水量、日照时数的变化趋势在空间分布上存在着一定的区域差异。     

Potassium→ammonium exchange of two benchmark soils from Botswana and its implication for nitrogen economy of the soils

Ion exchange preferences for NH₄⁺ and K⁺ by soil exchanger surface can greatly affect the NO₃^? leaching into groundwater and nitrogen-use efficiency in agricultural production. Since NH₄⁺ and K⁺ salts are usually applied together as fertilizers, the binary K→NH₄ exchange of two benchmark Botswana soils, Pellustert and a Haplustalf, was studied to determine the selectivity coefficients and the thermodynamic exchange constant with special reference to N economy. The Vanselow and the Gaines and Thomas coefficients indicated preference for NH₄⁺ by the Pellustert and K by the Haplustalf across the exchanger phase composition. The equilibrium constant (K_ex) was 1.807 for the Pellustert and 0.174 for the Haplustalf. The exchange free energy (ΔG_ex⁰) was ?1.467 kJ mol^?1 for the Pellustert and 4.334 kJ mol^?1 for the Haplustalf. Negative ΔG_ex⁰ for the Pellustert is consistent with preference for NH₄⁺ to K⁺ in contrast to positive ΔG_ex⁰ for the Haplustalf. The greater stability of NH₄X than KX complex in the Pellustert, and KX than NH₄X in the Haplustalf, would mean increased residence time of NH₄⁺ in the Pellustert than the Haplustalf. The implication of short residence time of NH₄⁺ in soil is rapid nitrification, thereby leading to NO₃^??N leaching losses and possible groundwater contamination.     

红壤对铝锰离子的吸附特征 Ⅴ·稀溶液中铝锰离子的交换吸附行为

研究了贴近自然的稀溶液条件下铝、锰离子交换吸附的行为,结果是:铝、锰与钙、钾离子的交换吸附仍符合一般的离子交换规律,但也不遵守比例定律。讨论了代入量/代出量的摩尔比<1时的交换吸附、临界点及其机理。对k、K、1/n、r进行了表述,其中k偏高,K则偏低。从热力学角度进一步论证了红壤铝质化即酸化的自然趋势,并揭示了钙与铝、钾离子交换吸附的能量特征。     

Water storage,surface, and structural properties of sandy forest humus horizons

In this paper, we tried to find interrelations between water retention properties, surface characteristics, and structural features of sandy soils rich in organic matter. Raw humic, epihumic, and endohumic horizons of four acidic sandy forest soils were selected for this study. Specific areas and water adsorption energies were estimated from water vapor adsorption isotherms, micropore (nanometer range) parameters from desorption isotherms, mesopore (micrometer range) parameters from mercury intrusion porosimetry, and macropore (millimeter range) parameters from water retention curves measured using combined suction plate and pressure chamber methods. In the studied soils, pore volumes in all pore ranges were proportional to soil organic matter content. Thin column wicking technique was used to determine migration velocity vs. time dependence in the samples beds for a range of liquids of various surface tensions. From these dependencies the surface free energy and its components were estimated that were used for calculation of water contact angles and forces of interparticle interaction via a water meniscus. The dominant interactions in the studied soils were dispersive Lifshitz‐Van der Waals forces. In the two upper horizons polar acid‐base interactions were absent, however in the deepest horizons, high input of polar interactions occurred, due practically to electron‐donor component of the surface free energy. The electron‐acceptor contribution was low. The wettability of the soils was low in upper horizons as indicated by high water contact angles.     

红壤对铝锰离子的吸附特征 Ⅴ.稀溶液中铝锰离子的交换吸附行为

研究了贴近自然的稀溶液条件下铝、锰离子交换吸附的行为，结果是：铝、锰与钙、钾离子的交换吸附仍符合一般的离子交换规律，但也不遵守比例定律。讨论了代入量／代出量的摩尔比〈1时的交换吸附、临界点及其机理。对k、K、1/n、r进行了表述，其中k偏高，K则偏低。从热力学角度进一步论证了红壤铝质化即酸化的自然趋势，并揭示了钙与铝、钾离子交换吸附的能量特征。