离子强度及pH对不同类型土壤中胶体释放的影响

采用实验室土柱纵向淋溶法,研究了离子强度及pH变化对常熟乌栅土原状、扰动土柱以及东北黑土、江西红壤扰动土柱土壤胶体释放的影响。结果表明离子强度变化对我国不同类型土壤胶体释放影响不同：淋洗液电解质为NaCl时,对于常熟乌栅土以及东北黑土,离子强度减小促进胶体的释放,反之抑制胶体的释放;对于江西红壤,离子强度变化对土壤胶体释放则不产生影响。淋洗液电解质为CaCl2条件下,土壤胶体的释放量低于淋洗液为NaCl,且离子强度变化对三种土壤胶体的释放均不产生明显影响。相同条件下,常熟乌栅土及东北黑土胶体释放量远远大于江西红壤,pH变化则对上述类型土壤胶体释放的影响不明显。研究结果有助于进一步阐明水化学条件的变化对我国不同类型土壤胶体释放的影响规律。     

Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)在红壤胶体和非胶体颗粒上吸附的比较

研究了湖南长沙和海南昆仑的2种红壤胶体和非胶体的矿物组成、阳离子交换量(CEC)及Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)在土壤胶体和非胶体颗粒表面的吸附行为,以明确红壤胶体对土壤表面化学性质的贡献。X射线衍射分析结果表明,两种红壤胶体的矿物组成均以次生矿物为主,次生矿物又以1∶1型高岭石所占比例最高。土壤非胶体颗粒中石英等原生矿物含量较高。土壤铁铝氧化物主要富集在土壤胶体部分,土壤胶体颗粒中游离氧化铁和游离氧化铝含量明显高于非胶体颗粒,如湖南长沙红壤胶体颗粒游离氧化铁的含量为78.03 g kg~(-1),而非胶体颗粒中仅为9.93 g kg~(-1)。土壤胶体颗粒的CEC显著高于非胶体颗粒部分,2种红壤胶体的CEC约为非胶体的12倍。等温吸附实验结果表明,土壤胶体颗粒对Cu(Ⅱ)、Pb(Ⅱ)与Cd(Ⅱ)的最大吸附量和吸附亲和力均显著大于非胶体颗粒,湖南红壤胶体对3种重金属的吸附量大于海南红壤胶体,与土壤胶体的矿物组成和CEC大小一致。Cd(Ⅱ)在红壤胶体和非胶体颗粒表面主要发生静电吸附,而静电吸附和非静电吸附两种机制均对Cu(Ⅱ)和Pb(Ⅱ)的吸附有重要贡献。     

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。     

Btk蛋白在红壤胶体上的吸附解吸行为及其对杀虫活性的影响

研究了苏云金芽胞杆菌库斯塔克亚种（Btk）两种分子量不同的杀虫蛋白（65 kDa和130 kDa）在红壤胶体上的吸附、解吸和杀虫活性。Btk杀虫蛋白容易被红壤胶体吸附,0.5 h即达到吸附平衡,65 kDa蛋白的吸附速率高于130 kDa蛋白。两种Btk杀虫蛋白在0.1 mol L^-1Tris缓冲液（pH 8）中的等温吸附曲线均符合Langmuir方程（R²>0.992）,65 kDa蛋白的吸附量高于130 kDa蛋白。在10～50℃范围内,温度升高吸附量略有降低。pH 6～8范围内,吸附量随pH升高而下降。两种Bt蛋白在红壤胶体吸附前后对棉铃虫均具有杀虫活性,而且吸附后杀虫活性提高了2～5倍。解吸实验表明,Btk杀虫蛋白与红壤胶体结合比较牢固,吸附态65 kDa蛋白和130 kDa蛋白经3次去离子水解吸,总解吸率分别为37.2%和22.9%,经3次pH8的Tris缓冲液解吸,总解吸率分别为20.7%和14.8%。红外光谱分析表明,两种分子量的Bt蛋白在吸附前后结构没有明显变化。透射电镜分析表明,吸附前后红壤胶体颗粒粒径未发生改变。吸附态Bt蛋白杀虫活性提高且不易被解吸,提示转Bt基因作物释放蛋白可能存在环境风险。     

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。     

土壤胶体对砂质土柱中草萘胺迁移的影响

采用室内砂柱模拟试验方法研究了红壤和黑土两种土壤胶体对草萘胺在砂质土柱中迁移的影响。结果表明,整个淋滤过程中红壤和黑土胶体的回收率比较高,分别达到66．76％和74．75％;胶体促进了草萘胺在砂质土柱中的迁移,与对照相比（无胶体）,加入红壤和黑土胶体后草萘胺的回收率分别提高了9．82％和10．63％。但是吸附在胶体上迁移的草萘胺数量比较少,只占到迁移总量的1．15％（红壤）和1．68％（黑土）,物理非平衡机制可能在迁移过程中起支配作用。     

氧化还原条件下有机物料对酸性土壤pH、铁形态和铜吸附解吸的影响

研究了添加有机物料对水稻土、红壤和砖红壤在干湿交替一次以后土壤pH、铁的形态和对铜吸附解吸行为的影响。结果表明,添加有机物料使得土壤pH升高,且随着有机物料加入量的增加而升高。与对照相比,添加有机物料可使水稻土、红壤和砖红壤的pH分别上升1.55、0.8和1.33个pH单位。红壤和砖红壤中无定形氧化铁含量增加,而水稻土中变化不大。在铜的平衡浓度为0.2 mmol/L时,添加有机物料培养可使水稻土、红壤和砖红壤铜的吸附量分别增加6.7、10.3和3.6 mmol/kg。     

2，4-二氯苯氧基乙酸在土壤中的吸附淋溶特性

农药在土壤中的吸附和淋溶特性是评价其环境行为的重要指标,特别是决定了其在土壤中的迁移性。本文分别利用振荡平衡法和柱淋溶法研究了2,4-二氯苯氧基乙酸（2,4-D）在不同土壤中的吸附和淋溶特性及其影响因素。结果表明,2,4-D在3种供试土壤上的吸附特性能较好地用线性吸附等温线拟合,吸附常数心在0．95-1．54L·kg^-1之间,很难被土壤吸附。影响2,4-D在土壤中吸附的因素主要是土壤pH值,其次是有机质含量。土壤pH值增高,离子态的2,4-D量增加,吸附减弱;2,4-D在土壤中具有较强的淋溶性,影响其淋溶性能的主要因素是土壤pH值,pH值越高,淋溶性能越强。     

病原菌在红壤胶体上的吸附机制研究

研究了pH和KCl离子强度对猪链球菌和大肠杆菌在红壤胶体表面吸附的影响,结合表面物化性质和Derjaguin-Landau-Verwey-Overbeek(DLVO)理论分析互作机制。结果表明,细菌在红壤胶体表面的吸附等温线能较好拟合Freundlich方程(R20.97),猪链球菌在红壤胶体表面吸附的分配系数(Kf)是大肠杆菌的4.5倍～6.1倍,细菌在去有机质胶体表面吸附的Kf值为含有机质胶体的2.4倍～3.2倍。比表面积越大或zeta电位绝对值越小,细菌吸附能力越强,吸附态细菌位于距红壤胶体表面90～100 nm处的次级小能位置。随着体系pH降低(9.0～4.0)或离子强度增大(1～10 mmol L-1),细菌与红壤胶体互作能障降低,细菌吸附量增大,吸附机制符合DLVO理论;而在高离子强度下(50～100 mmol L-1),猪链球菌吸附量降低了3.4%～5.6%,表明除DLVO作用力外,非DLVO作用力如空间位阻排斥和疏水作用对吸附也有贡献。     

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     

Transport and re-entrainment of soil colloids in saturated packed column: effects of pH and ionic strength

Purpose

Colloid migration in subsurface environments has attracted considerable attention in recent years because of its suspected role in facilitating transport of strongly adsorbed contaminants to groundwater. The influence of bulk solution pH or ionic strength on model colloid (i.e., latex microsphere, amorphous silica colloids) transport is well established, while little attention has been paid to water-dispersible soil colloids. In this study, saturated packed columns were conducted to explore the mechanism of transport and fate of water-dispersible soil colloids and facilitating transport of Cu during transients in solution chemistry.

Materials and methods

Water-dispersible soil colloids were fractionated from a Cu-contaminated soil sample. Transport of soil colloidal suspensions was conducted with varying pH and ionic strengths, and then, re-entrainment of those retained colloids after completion the transport experiments was conducted by changing pore water solution transient ionic strength and pH conditions. Meanwhile, transport and fate of the Cu strongly adsorbed on the soil colloids were determined under different ionic strength conditions.

Results and discussion

The transport behavior of soil colloids in porous media was found to depend on the pH and ionic strengths of bulk solution. An increase in solution ionic strength and decrease in solution pH resulted in greater deposition which was revealed by the collision efficiency (??). It increased from 0.15 to 1.0 when solution composition changed from 0 to 50?mM NaNO₃ and decreased dramatically from 1.0 to 0.035 as the solution pH converted from 2.97 to 8.94. The results were in agreement with Derjaguin?CLandau?CVerwey?COverbeek theory. Upon stepwise reduction in ionic strength of eluting fluid or enhancement in its pH, a sharp release of colloids retained in the column occurred in each step. Meanwhile, the value of FRE _NaOH that reveals the effect of NaOH solution at pH?11 on the mobilization of retained colloids deposited in the primary minimum increased from 38.6% to 64.6% when the ionic strength of bulk solution changed from 0 to 50?mM NaNO₃ and decreased from 86.7% to 35.8% as the solution pH from 2.97 to 8.94. In addition, the transport and fate of the Cu strongly adsorbed on soil colloids were highly consistent with the results of soil colloids.

Conclusions

The colloid collision efficiency (??) decreased as the pH of bulk solution increased and increased as the ionic strength of bulk solution increased in saturated columns packed with pure quartz sand, and NaOH solution at pH?11 poses a predominant role on mobilization of the retained colloids deposited in the primary minimum. Meanwhile, the strongly adsorbed Cu on soil colloids almost cannot be detached from its carrier under the competition of coexisted cations in the bulk solution and cotransport with its carrier under different ionic strengths.     

草萘胺在五种土壤及其胶体上的吸附行为

土壤胶体是土壤中颗粒最细小的部分,由于具有巨大的比表面积和较高的吸附容量,是环境中污染物的重要吸附剂,直接影响到污染物的归趋和生物有效性.本文采用批次吸附试验的方法,研究了农药草萘胺在黄棕壤等5种土壤及土壤胶体上的吸附行为.结果表明,草萘胺在供试土壤及胶体上的吸附均能很好地符合Freundlich方程;与本体土壤相比,...     

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。     

土壤胶体在不同饱和度土壤介质中的释放与淋溶行为研究

采用饱和与非饱和填充土柱纵向淋溶研究方法,结合对流弥散模型方程（CDE）对穿透曲线的拟合计算,全面考察了土壤介质水饱和度、土壤水pH/离子强度、土壤孔隙水流速和土壤胶体颗粒大小对天然土壤胶体在实际土壤介质中释放、沉积迁移行为的影响。分别获取胶体扩散系数和阻滞因子值,定量说明实验中水化学、水动力学等条件的作用影响力。结果显示,介质不饱和条件不利于胶体的释放和淋溶;高pH和低离子强度条件对土壤胶体释放与迁移有利;淋溶过程的间断干扰,可以促使土壤胶体的增量淋溶释放;淋溶强度及胶体颗粒粒径大小,能够影响胶体穿透时间和穿透浓度峰值大小。     

根瘤菌存在下土壤胶体和矿物对镉的吸附

Experiments were conducted to study the adsorption of Cd on two soil collids(red soil and yellowbrown soil) and three variable-charge minerals (goethite,noncrystalline Fe oxide and kaolin) in the absence and presence of rhizobia.The tested strain Rhizobium fredii C6,tolerant to 0.8 mmol L^-1 Cd,was selected from 30 rhizobial strains.Results showed that the isotherms for the adsorption of Cd by examined soil colloids and minerals in the presence of rhizobia could be described by Langmuir equation.Within the range of the numbers of rhizobial cells studied,the amount of Cd adsorbed by each system increased with increasing rhizobial cells,Greater increases for the adsorption of Cd were found in red soil and kaolin systems.Rhizobia influence on the adsorption of Cd by examined soil colloids and minerals was different from that on the adsorption of Cu.The presence of rhizobia increased the adsorption affinity of soil colloids and minerals for Cd,particularly for the goethite and kaolin systems.The discrepancies in the influence of rhizobia on the adsorbability and affinity of selected soil colloids and minerals for Cd suggesed the different interactions of rhizobia with various soil components.It is assumed that bacterial biomass plays an important role in controlling the mobility and bioavailability of Cd in soils with kaolinite and goethite as the major colloidal compnents,such as in variable-charge soil.     

铬与对氯苯胺的交互作用对其在土壤胶体上的反应的影响

Adsorption of Cr(VI) and p-chloroaniline on three typical soil colloids and pH influence were studied using batch equilibrium method.Both of Cr(VI) and p-chloroaniline adsorption on the colloids could be well described by general adsorption simulation equations,The adsorption processes changed with media pH.When Cr(VI) and p-chloroaniline coexisted on soil colloids,their interactions could be observed in a certain pH range to be accompanied with Cr(VI) reduction,which clearly suggested that a surface catalytic reaction occurred in this system.Soil colloid acted as an effcient catalyst for the interaction of Cr(VI)and p-chloroaniline.The pH values at which no interaction was observed were 4.0,4.5and 5.0 for the colloids of indigotic black soil,yellow-brown soil and latosol,respectively,Capillary electrophoresis used to analyze p-chloroaniline provided a high separation efficiency and short separation time,and needed no more extensive pretreatment of samples.     

Stability and transportability of biosolid colloids through undisturbed soil monoliths

This study evaluated the stability of water-suspended biosolid colloids fractionated from municipal and agricultural wastes and their transportability through undisturbed soil monoliths. The aim of the study was to assess potential risks posed by dispersed biosolid colloid particles as carriers of contaminants associated with organic waste amendments applied to soils. All biosolid colloids showed remarkable stability over a wide range of pH conditions, with 50–90% remaining in suspension after 24 h. Lime-stabilized biosolid colloids (LSB) were more stable than poultry manure (PMB) and aerobically digested (ADB) biosolid colloids, with pH and organic matter (OM) content being the dominant factors influencing colloid stability. However, increased colloid stability did not always result in greater transportability. In spite of their higher overall stability, LSB colloids showed low transportability potential through undisturbed soil monoliths averaging < 0.1C/C₀, probably due to carbonate dissolution and increased ionic interaction with the soil matrix. The ADB and PMB colloids, with the highest OM content, exhibited increased mobility, particularly through soils with significant macroporosity. Breakthrough curves were mostly irregular, suggesting considerable macropore flow and increased interaction with the soil matrix. Eluent pH and EC fluctuations appeared to mainly affect LSB colloid transport, while the mobility of the remaining biosolid colloids was maintained over a wide range of ionic conditions. The findings of this study suggest that some biosolid colloids derived from soil-applied agricultural or municipal wastes may exhibit considerable mobility through soil macropores with potential to migrate to great distances in subsoil environments. Considering the high surface charge and electronegativity of these colloids, they may be a significant vector for hydrophobic contaminant transport and pollution of groundwater resources.     

Size Characterization by Laser Granulometry of Colloids Extracted from Compost at Different Temperatures

The objective of this work was to characterize colloids extracted from composts and their potential retention in soils. Compost made of sludge and green wastes was sampled (i) during the fermentation phase and (ii) after maturation. The same kind of compost was used in a long-term field experiment at Feucherolles (France), near Paris where amended and nonamended soils were sampled. The colloidal fraction was extracted from composts in water at room temperature (20°C) and compared to the colloidal fraction extracted from the soil. Composts were also extracted by pressurized hot liquid water at 50, 125 and 175°C. The total organic carbon of the extracts was measured and the particle size distribution (PSD) of colloidal extracts was analyzed by laser granulometry. The diameters of the colloids extracted from the soil ranged between 0.040 and 0.300 μm, independently of the temperature. For composts, it varied from 0.040 to 3.200 μm when extraction was done at 20°C, while at higher temperatures, much more organic matter was extracted, and colloid diameters ranged from 0.040 μm to 0.200 μm. The water-soluble C decreased and the size of colloids recovered in water at temperatures below 50°C increased when compost maturity increased. The adsorption on soils of colloidal particles extracted from composts was characterized. The largest adsorption (up to 30% of the initial soluble C) occurred with the extracts recovered at high temperature, in relation to the more hydrophobic properties of the colloids extracted with hot water maintained in subcritical conditions. After adsorption, the particle size distribution in the colloidal fraction extracted at 20°C moved towards finer fractions; by contrast, the colloidal fraction extracted at 175°C moved towards coarser fractions. The coarsest colloids coming from the soil disappeared during the adsorption experiment, probably because of the coprecipitation with the finest colloids coming from compost.     

土壤胶体对蛋白质的吸附

土壤有机-无机复合体是土壤肥力的物质基础之一,不仅依随成土过程而发生变化,人类耕作利用也可产生影响。     

Adsorption and degradation of 2,4-dichlorophenoxyacetic acid in spiked soil with Fe0 nanoparticles supported by biochar

This work studies the adsorption and degradation of 2,4-dichlorophenoxyacetic (2,4-D) in spiked soil with nanoscale Fe⁰ particles (nFe⁰) and biochar derived from maize straw. When biochar concentration was high, the adsorption capacity of soil was enhanced. Furthermore, 2,4-D degraded completely at loading rates of 0.33 and 0.17 g/L nFe⁰ plus biochar (initial 2,4-D concentration of 10 mg/g) within 40 h, according to equilibrium data. Additionally, the theoretical concentration of chloridion was approximately 84%. Further analysis indicated that the effect of nFe⁰ on 2,4-D degradation was weaker in soil columns than that in soil slurry. By contrast, 2,4-D degradation is positively influenced by biochar application, which prevented the aggregation and corrosion of Fe nanoparticles. Although the enhanced capacity for 2,4-D adsorption on the soil decelerated dechlorination rate, long-term nFe⁰ activity was generated. After 72 h, the efficiency of 2,4-D degradation was approximately 53.2% in the soil columns with biochar support.