磷-铅-柠檬酸在红壤胶体上相互作用机理初探

以红壤胶体为对象,通过等温平衡试验,研究了柠檬酸对红壤胶体吸附磷的影响,以及吸附磷和柠檬酸后弃去上清液(次级吸附)和保留上清液(共吸附)两种方式对红壤胶体固定铅的影响。结果表明,柠檬酸对红壤胶体磷吸附产生抑制作用,且随着柠檬酸浓度增加而抑制作用增强;用Langmuir方程拟合时,红壤胶体对磷的吸附反应常数K、最大吸附量X m均随柠檬酸初始浓度增加而降低。吸附磷和柠檬酸后,两种处理方式对铅的固定量影响有明显差异,总体上,次级吸附试验中铅的固定量低于共吸附;且两种方式中铅的固定量均随磷初始浓度及磷吸附量的增加而增加,随柠檬酸浓度升高而降低。共吸附中铅固定量在柠檬酸初始浓度为0.1 mmol L-1和磷初始浓度小于0.4 mmol L-1时达到较高值,说明在此浓度下磷和柠檬酸的共同存在促进了红壤胶体对铅的固定。     

酒石酸对黏粒矿物上酸性磷酸酶吸附及活性的影响

采用平衡批处理法,研究了模拟根系分泌物——酒石酸溶液的浓度(0~80 mmol L-1)、pH(2.5~7.0)对酸性磷酸酶在针铁矿、高岭石及黄棕壤和砖红壤胶体(<2μm)上的吸附及比活性影响。结果表明,当酒石酸浓度由0 mmol L-1(作为对照)升高至80 mmol L-1时,酸性磷酸酶在供试土壤胶体和矿物表面的吸附量先急剧降低(0~5mmol L-1之间),后逐渐达到平衡;以羟基化表面为主的针铁矿对酸性磷酸酶的吸附百分率受酒石酸浓度的影响最大,吸附百分率从对照的96.2%降至80 mmolL-1酒石酸浓度时的33.7%,其他以层状铝硅酸盐矿物为主的供试土壤胶体和高岭石则受影响较小,吸附百分率从对照的76.3%~60.6%降至80 mmol L-1酒石酸浓度时的56.2%~41.6%。酸性磷酸酶在酒石酸体系中的最大吸附pH点均在该酶的等电点酸侧,这可能与酒石酸对矿物表面的电荷性质改变有关;酒石酸体系中,针铁矿上酸性磷酸酶的比活性远高于其它供试土壤胶体,该酶的最适比活性点随胶体类型的不同而无变化或有所高移。     

铁铝氧化物–层状硅酸盐矿物互作对Cr (Ⅵ)和As (Ⅴ)吸附的影响

以高岭石、蒙脱土、针铁矿和三水铝石四种单一典型土壤矿物以及针铁矿-蒙脱石和三水铝石-蒙脱石（质量比为1:1）两种代表性土壤矿物复合体为吸附材料，采用吸附平衡实验、能谱分析（(EDS）、红外光谱、扫描电镜、酸碱滴定和zeta电位测定等方法，研究了铁铝氧化物与层状硅酸盐矿物之间的相互作用对Cr(Ⅵ)和As(Ⅴ)吸附的影响及其机制。吸附平衡实验和EDS实验结果表明，两种复合体对Cr(Ⅵ)和As(Ⅴ)的吸附容量均小于其两种组成矿物单一体系吸附量的平均值，即铁铝氧化物与蒙脱石的互作降低了这些氧化物对Cr(Ⅵ)和As(Ⅴ)的吸附能力。表面性质表征结果表明，与蒙脱石复合后，针铁矿与三水铝石表面的正电荷均被完全中和，电荷符号发生反转。与理论值相比，三水铝石-蒙脱石复合体的表面位点总浓度无明显变化，比表面积减小。针铁矿-蒙脱石复合体的比表面积与理论值无明显差异，但矿物表面位点浓度减小，表面羟基红外吸收峰强度减弱。氧化物与层状硅酸盐矿物互作改变了矿物表面性质，这可能是导致氧化物对Cr(Ⅵ)和As(Ⅴ)的吸附能力降低的主要原因。当评估污染元素在土壤中有效性时应当考虑土壤固相组分间的互作对离子吸附的影响。     

离子强度和磷酸盐对铁铝矿物及土壤吸附As（V）的影响

选用针铁矿、赤铁矿、水铁矿、水铝矿4种铁铝矿物以及性质差异较大的黑土、紫色土和红壤3种土壤,研究离子强度和磷酸盐对其吸附As（V）的影响。结果表明,在0．01、0．1、1mol·L^-13种离子强度下,矿物和土壤对As（V）的吸附量无明显差异或随离子强度增大而增大,其对砷的吸附以专性吸附为主。磷酸盐对矿物和土壤吸附砷的影响与其添加顺序及摩尔浓度比有关。水铝矿和水铁矿在这3种添加顺序下的砷吸附量无明显差异,仅在P／As摩尔比较大时表现出下降趋势;而在针铁矿和赤铁矿两种矿物上,先添加砷时的砷吸附量高于先添加磷时或两者同时添加时,且砷吸附量随WAs摩尔比的增加而逐渐下降。在黑土、紫色土和红壤上,先添加砷比先添加磷或两者同时添加时的砷吸附量均要高,尤其是在紫色土上。随P／As摩尔比升高,土壤对砷的吸附量表现出下降趋势。     

有机酸对针铁矿和膨润土吸附Cd2+、Pb2+的影响

用平衡吸附法研究了不同浓度的有机酸（乙酸、酒石酸和柠檬酸）对针铁矿和膨润土吸附Cd^2＋、Pb^2＋的影响。结果表明：（1）低浓度（〈0．6mmolL^-1）有机酸促进供试矿物吸附Cd^2＋和Pb^2＋，随着有机酸浓度增加，吸附逐渐被抑制。高浓度（〉1．0mmolL^-1）有机酸对Pb^2＋吸附的抑制作用比对Cd^2＋的强。有机酸浓度的变化对针铁矿Cd^2＋、Pb^2＋吸附率的影响大于对膨润土的。（2）不同Cd^2＋浓度下，有机酸对膨润土Cd^2＋吸附强度的影响大于针铁矿。加入高浓度Cd^2＋（8．0mmolL^-1）时，低浓度有机酸对膨润土吸附Cd^2＋的促进作用比加入低浓度Cd^2＋（0．4mmolL^-1）时明显，高浓度有机酸对膨润土吸附Cd^2＋的抑制作用与低浓度Cd^2＋时相近。（3）低浓度有机酸（〈0．6mmolL^-1）时，酒石酸、柠檬酸对针铁矿吸附Cd^2＋的促进作用大于乙酸，而它们对膨润土吸附Cd^2＋的促进作用相似；在三种有机酸高浓度（〉1．0mmol L^-1）时，针铁矿对Cd^2＋的吸附都趋于稳定，而柠檬酸对膨润土吸附Cd^2＋的抑制作用比乙酸和酒石酸的明显。不同种类有机酸下，矿物对Pb^2＋吸附率大小的变化基本一致。     

磷酸盐对土壤胶体和矿物表面吸附酸性磷酸酶的影响

研究了系列浓度磷酸盐体系中 ,酸性磷酸酶在黄棕壤、砖红壤胶体和高岭石、针铁矿及δ MnO2 表面的吸附特点。结果表明 :随着磷酸盐浓度升高 ,磷酸酶在土壤胶体和矿物上的等温吸附曲线类型逐渐由L型向C型转化 ,等温吸附方程由Langmuir方程向线性方程转化 ,这种转化可能与磷酸和酶在胶体矿物表面对不同点位的利用及其能量特点有关。随着体系中磷酸盐浓度的增加 ,酶吸附量呈现先急剧下降后逐渐稳定的趋势。磷酸盐对土壤胶体和矿物上酶吸附的影响决定于矿物表面的类型特别是羟基的数量、体系中磷酸盐浓度及酶的加入量。针铁矿及含铁铝氧化物较多的砖红壤胶体对酶的吸附受磷酸盐的抑制作用最为显著。     

锰掺杂对针铁矿的结构、表面性质及吸附硒的影响

水热条件下制备了针铁矿(Goe)和不同含量锰掺杂产物(G-Mn0.1、G-Mn0.2、G-Mn0.3和G-Mn0.5),用X-射线衍射(XRD)、透射电镜(TEM)、氮气物理性吸附、Zeta电位分析、酸碱滴定等手段对样品进行了表征,并研究其对亚硒酸盐(Se(Ⅳ))和硒酸盐(Se(Ⅵ))的吸附特性。结果表明:低比例的锰掺杂(锰/铁的摩尔比RMn/Fe=0.1~0.2)显著促进了针铁矿晶体沿b轴方向生长,导致针铁矿颗粒的长径比增大,形貌由短纺锤体形变为大长径比的扁平针状;当RMn/Fe=0.3~0.5时,样品中出现了大量的掺锰磁铁矿,且针铁矿晶体的b轴方向生长受到严重的抑制而a轴方向生长受到一定程度的促进并导致针铁矿颗粒呈纤细状。Goe、G-Mn0.2和G-Mn0.5的比表面积分别为36.78、53.22和71.33 m2·g–1,表面分形度分别为2.31、2.53和2.59,平均孔径分别为13.73、15.59、6.92 nm,Zeta电位零点分别为7.36、6.58和5.31,pH5.0时的Zeta电位分别为40.5、35.3和4.92 mV。3种样品的表面活性羟基密度表现为Goe相似文献   

低分子量有机酸对胶体矿物吸附酸性磷酸酶和牛血清白蛋白的影响 Ⅰ.乙酸的影响

研究了不同pH和乙酸浓度下 ,乙酸对酸性磷酸酶和牛血清白蛋白 (BSA)在土壤胶体、矿物表面吸附的影响。结果表明 ,在pH 2～ 8的乙酸体系中 ,酸性磷酸酶和BSA在胶体矿物表面的最大吸附pH值一般出现在蛋白的等电点和矿物的电荷零点 (PZC)之间。各土壤胶体和粘粒矿物对酶和BSA的吸附量大小顺序为 :针铁矿 黄棕壤 >砖红壤 >高岭石 >二氧化锰。乙酸浓度对蛋白分子在胶体矿物表面的吸附量和吸附结合能具有较显著影响 ,在 0～ 2 0 0mmolL- 1范围 ,随着乙酸浓度的增加 ,蛋白吸附量呈现出先升高 ,后降低 ,再稳定的趋势 ,而吸附结合能的变化与此相反。本文还就乙酸对酶和BSA吸附影响的可能机理进行了初步探讨。     

供磷水平对平邑甜茶幼苗NO3-吸收、利用特性的影响

运用~(15)N示踪及非损伤微测技术,研究了不同供磷水平(0 mmol×L~(-1)、1.0 mmol×L~(-1)、2.0 mmol×L~(-1)、3.0 mmol×L~(-1)、4.0 mmol×L~(-1)、6.0 mmol×L~(-1)、8.0 mmol×L~(-1)、12.0 mmol×L~(-1)和16.0 mmol×L~(-1) H_2PO_4~-)对平邑甜茶幼苗NO_3~--N吸收及利用特性的影响,为提高果园氮肥利用效率提供理论依据。结果表明,在低磷水平(0~1.0 mmol×L~(-1))时,平邑甜茶根系长度、根系总表面积较小,且根尖数较少。随着供磷水平的增加,在2.0~4.0 mmol×L~(-1)磷浓度处理时,平邑甜茶幼苗生物量、根系长度、根系总表面积及根尖数显著高于其他处理。而在6.0~16.0 mmol×L~(-1)时,过量供磷抑制了根系的生长,使平邑甜茶幼苗根系长度、表面积均大幅降低,根尖数量骤降。非损伤扫描离子选择电极测试表明,当生长介质磷浓度在3.0~6.0 mmol×L~(-1)时,平邑甜茶对NO_3~-有吸收作用,并在3.0 mmol×L~(-1)磷浓度时其吸收速率最高。而在0~2 mmol×L~(-1)及8.0~16.0 mmol×L~(-1)磷浓度处理下,平邑甜茶对NO_3~-有外排作用。随供磷水平的增加,各器官从肥料中吸收分配到的~(15)N量对该器官全氮量的贡献率(Ndff)及植株氮素利用率呈现先升高后降低的趋势,4.0 mmol×L~(-1)磷浓度时植株氮素利用率最大,为42.24%,超过4.0 mmol×L~(-1)植株氮素利用率显著降低。适当充足的供磷刺激了幼苗根系生长,从而促进平邑甜茶对氮素的获取,过量的NO_3~-抑制了平邑甜茶根系的生长,同时叶片硝酸还原酶的活性受到抑制,因此其氮素吸收和利用效率较低。因此,磷浓度在3.0~4.0 mmol×L~(-1)时最有利于平邑甜茶幼苗的生长及氮素的吸收利用。     

不同pH下有机酸对针铁矿和膨润土吸附Cd2+、Pb2+的影响

用平衡吸附法研究了不同pH下,三种有机酸(乙酸、酒石酸和柠檬酸)对针铁矿和膨润土等温吸附Cd2 、Pb2 的影响。结果表明:在加入的Cd2 、Pb2 浓度分别小于0.2 mmol L-1和4.0 mmol L-1时,针铁矿和膨润土吸附平衡体系的pH随加入重金属浓度的增加而降低,膨润土体系的pH降低更明显。在有机酸作用下,pH对针铁矿和膨润土吸附Cd2 、Pb2 的影响差异显著。3酒石酸>乙酸,其对膨润土吸附的影响差异不明显。     

有机酸对高岭石, 针铁矿和水铝英石吸附镉的影响

Effects of organic acids （oxalic, acetic, and citric） on adsorption characteristics of Cadmium （Cd） on soil clay minerals （kaolinite, goethite, and bayerite） were studied under different concentrations and different pH values. Although the types of organic acids and minerals were different, the effects of the organic acids on the adsorption of Cd on the minerals were similar, i.e., the amount of adsorbed Cd with an initial solution pH of 5.0 and initial Cd concentration of 35 mg L^-1 increased with increasing concentration of the organic acid in solution at lower concentrations, and decreased at higher concentrations. The percentage of Cd adsorbed on the minerals in the presence of the organic acids increased considerably with increasing pH of the solution. Meanwhile, different Cd adsorption in the presence of the organic acids, due to different properties on both organic acids and clay minerals, on kaolinite, goethite, or bayerite for different pHs or organic acid concentrations was found.     

Phosphate desorption from the surface of soil mineral particles by a phosphate-solubilizing fungus

High phosphate (Pi) sorption in soils is a serious limiting factor for plant productivity and Pi fertilization efficiency, particularly in highly weathered and volcanic ash soils. In these soils, the sorbed Pi is so strongly held on the surfaces of reactive minerals that it is not available for plant root uptake. The use of phosphate-solubilizing microorganisms (PSM) capable of Pi desorption seems to be a complementary alternative in the management of these soils. The aim of this study was to evaluate the effectiveness of the soil fungus Mortierella sp., a known PSM, to desorb Pi from four soil minerals differing in their Pi sorption capacity. The fungus was effective in desorbing Pi from all tested minerals except from allophane, and its desorption depended on the production of oxalic acid. The effectiveness of the fungus to desorb Pi was ranked as montmorillonite > kaolinite > goethite > allophane. The quantity of desorbed Pi increased by increasing the amount of sorbed Pi. The Pi sorption capacity expressed as P_0.2 value (amount of P required to increase a solution P concentration up to 0.2 mg L^?1) was a good indicator of the effectiveness of Mortierella sp. to desorb Pi from soil minerals.     

有机酸对几种土壤胶体吸附解吸镉离子的影响

用平衡法研究了有机酸对土壤胶体吸附 解吸Cd2 的影响。结果表明 ,黄棕壤、红壤、砖红壤胶体Cd2 最大吸附容量 (Qm)分别为 4 3 7、16 8、1 5 8mmolkg-1。在加入Cd2 浓度相同的条件下 ,土壤胶体Cd2 吸附量随有机酸浓度的升高呈峰形曲线变化。当有机酸与Cd2 共存时 (竞争吸附 ) ,低浓度的草酸 (小于0 5～ 2mmolL-1)或柠檬酸 (小于 0 0 2 5～ 0 2mmolL-1)提高Cd2 吸附量 ,高浓度的草酸或柠檬酸能降低Cd2 吸附量。吸附有机酸后的土壤胶体 (次级吸附 )对Cd2 次级吸附量的影响与竞争吸附一致 ,但两者的Cd2 吸附量变化幅度不一样。这是由于两种吸附体系液相中有机酸残留浓度不同所致。土壤胶体吸附态Cd2 的解吸结果表明 ,草酸浓度不仅影响Cd2 的总解吸量、总解吸率 ,还影响土壤胶体表面KNO3 解吸态与DTPA解吸态Cd2 的分配比例     

Adsorption of the insecticidal protein of Bacillus thuringiensis subsp. kurstaki by minerals: effects of inorganic salts

The persistence of the insecticidal protein of Bacillus thuringiensis (Bt) is enhanced by the reactivity with soil particles and may constitute a hazard to the soil ecosystem; however, studies on the fate of the Bt toxin in soil, especially in the presence of inorganic salts, are limited. The effects of different concentrations of KNO₃, KH₂PO₄ and NH₄H₂PO₄ on the adsorption of Bacillus thuringiensis toxin by kaolinite, montmorillonite, goethite and silicon dioxide were investigated. Results showed that small salt concentrations tended to enhance toxin adsorption, whereas large concentrations (> 10 mmol litre^?1) inhibited sorption. Similar results were observed regardless of the order in which toxin and inorganic salt were added. The degree to which individual salts affected adsorption decreased in the sequence for minerals, goethite > kaolinite ≥ montmorillonite > silicon dioxide, and for ions, H₂PO₄^? > NO₃^?, NH₄⁺ > K⁺. Our results indicate that inorganic salts can markedly influence the adsorption of Bt toxin by soil minerals. This investigation will help in evaluating the behaviour and fate of Bt toxins in the soil environment.     

不同pH、电解质浓度条件下草酸对针铁矿吸附Cd(II)的影响及机制

用吸附平衡法研究了不同草酸浓度、体系pH对针铁矿 (G)吸附Cd2+的影响与机制以及电解质 (KNO3)浓度对针铁矿、草酸化针铁矿 (G+40 )吸附Cd2+的影响差别及原因。结果表明 ,低浓度草酸 (1mmolL-1 )促进Cd2+的吸附 ;高浓度草酸 (1mmolL-1/sup )抑制Cd2+的吸附。已吸附在针铁矿表面的草酸对Cd2+ 吸附的影响与液相中草酸的影响不同 ,这主要与草酸引起的针铁矿表面电荷性质的变化、草酸在固液两相间的分配、草酸与Cd2+的配合作用和竞争作用有关。电解质 (KNO3)浓度对针铁矿和草酸化针铁矿吸附Cd2+的影响明显不同 ,随KNO3 浓度的提高 ,针铁矿的Cd吸附率由 44.5%增至 95%以上 ,而草酸化针铁矿吸附率由 29%降至6.2% ,这主要决定于二者的电荷零点 (PZC)和体系pH变化的不同。     

Effect of organic acids on the adsorption of copper,lead, and zinc by goethite

The adsorption of Cu, Pb, and Zn by synthetic goethite was studied in the absence and presence of oxalic, citric, and glutamic acids at different pH values. It was shown that, in the absence of an acid, the content of adsorbed metals increased with the increasing pH. The content of adsorbed cations at constant pH values decreased in the sequence: Cu > Pb > Zn. The simultaneous addition of metal cations and organic acids to the goethite suspension increased the content of the adsorbed elements. The oxalic and citric acids had similar effects on the adsorption of copper and lead in the studied pH range. The metal: acid concentration ratios significantly affected the adsorption of the heavy metals by goethite. An increase in the metal adsorption was observed to a certain metal: acid ratio, which was followed by a gradual decrease. The adsorption of the metals by goethite also depended on the properties of the metal cations and the organic ligands. The observed tendencies were attributed to the complexation of heavy metals with organic acid anions and the simultaneous sorption of acids at positively charged sites on the goethite surface with the formation of mineral-organic compounds, which significantly modified the surface properties of the mineral. The study of the effect of increasing lead concentrations in the solution on the copper adsorption by goethite in the absence, in the presence, and at the addition of an oxalic acid solution to the goethite suspension one hour before the beginning of the experiment showed that lead decreased the adsorption of copper in all the treatments. The possible mechanisms of the processes occurring in the system were considered.