西北旱作农田黄土对Pb(Ⅱ)的吸附-解吸行为研究

采用静态批次试验法研究西北旱作农田黄土对Pb(Ⅱ)的吸附等温线和动力学特性,通过正交试验揭示Pb(Ⅱ)的解吸行为。结果表明:黄土对Pb(Ⅱ)的吸附过程更好地符合Langmuir等温线方程和准二级动力学方程,拟合系数R2分别为0.9937和0.9964;Langmuir方程计算得出的黄土对Pb(Ⅱ)的最大吸附量qm为17.0068mg/g。吸附过程自发、吸热,反应后体系自由度略有增加。对比极差R值发现:影响解吸过程的主要因素为水土比和解吸时间,在水土比为150mL/g、解吸时间为3 h、解吸液pH值为5和解吸温度为288 K时,Pb(Ⅱ)的平均解吸率r为50.15%。去除有机质农田黄土对Pb(Ⅱ)的吸附量qe仅为6.6814mg/g,推测有机质在Pb(Ⅱ)的去除过程中有重要贡献。     

施磷对不同生育期棉田土壤磷素吸持特性的影响

以两种质地棉田土壤为材料,研究不同施磷处理对不同生育期棉田土壤磷吸附与解吸的影响.结果表明:各生育期磷素等温吸附曲线与Langmuir,Temkin和Freundlich方程拟合度均达极显著水平,尤以Freundlich方程拟合度最高,相关系数均在0.96以上;磷的吸附饱和度(DPS)、零净吸附浓度磷(EPC_0)、吸附量、解吸量和解吸率随施磷量的增加均呈增长趋势,而标准需磷量(SPR)呈下降趋势;以Freundlich方程估算原状棉田土壤各个生育期的需磷量,壤质棉田苗期、花铃期和吐絮期的需磷量(按含P_2O_5 46%的磷肥折算)分别为143.7,137.4 kg/hm~2和160.2 kg/hm~2,砂壤质棉田苗期、花铃期和吐絮期的需磷量分别为106.6,251.1 kg/hm~2和173.0 kg/hm~2.     

不同形态氧化铁对黄土性土壤吸附铅的影响

针对土壤含氧化铁的普遍性以及氧化铁对土壤理化性质的重要影响,探求氧化铁对土壤吸附重金属离子的作用与影响。采用了化学选择性溶提技术,分别去除黄土性母质上发育的古土壤、淋溶褐土和黄褐土中不同形态的氧化铁,采用了等温吸附试验,并以Langmuir和Freundlich方程拟合参数为指标,分析去除不同形态氧化铁前后土壤对Pb~(2+)的吸附特征。结果表明:原土壤对Pb~(2+)的吸附曲线逐渐递增,并无明显阶段特征,且更符合Freundlich方程;而去除不同形态氧化铁后的3类土壤对Pb~(2+)的吸附曲线均为L型,阶段特征显著,更加符合Langmuir方程,且土壤对Pb~(2+)的亲和力(KL)成倍增加;去除络合态铁和无定形氧化铁后,土壤对Pb~(2+)的最大吸附量均有不同程度增加,其中去除无定形氧化铁之后,古土壤对Pb~(2+)的最大吸附量增幅最大,增加了14.71 mg·g-1;去除游离态氧化铁后古土壤、淋溶褐土对Pb~(2+)的吸附量分别下降了5.95、3.10 mg·g-1,黄褐土对Pb~(2+)的吸附量则增加了2.98 mg·g-1。土壤中氧化铁对Pb~(2+)吸附能力与吸附容量的影响不完全依赖于氧化铁的含量,在很大程度上依赖于土壤中氧化铁的形态。对于不同氧化铁形态的土壤采用相应的化学溶提技术,能够获得具有较高吸附性能的粘土矿物环境材料。     

干旱区绿洲土壤镉-锌-铅复合污染物在芹菜中的富集迁移规律

以干旱区绿洲土壤为供试土壤,采用盆栽实验研究了镉-锌-铅复合污染物在土壤/芹菜系统中的迁移富集特征.结果表明:随着外源添加重金属量的增大,芹菜根和叶中重金属含量也增大;芹菜根对Cd、Pb、Zn吸收量与土壤中Cd、Pb、Zn含量、外源添加Cd、Pb、Zn量之间都达到极显著正相关,芹菜叶对Cd 、Zn的吸收量与土壤中Cd、Zn含量、外源添加Cd、Zn量之间都达到极显著正相关;多元线形回归分析可知,芹菜根吸收Cd、Pb、Zn并没有受到共存元素的影响;重金属元素从土壤中分别向芹菜根/叶的富集能力顺序都为Cd＞Zn＞Pb,重金属元素在芹菜体内的迁移能力顺序为Zn＞Cd＞Pb.     

绿洲油菜根际土壤中Cd,Pb赋存形态特征及其互作影响

采用盆栽试验,设计了Cd、Pb以及Cd/Pb复合胁迫三种污染情景模式种植油菜,利用Tessier连续提取法对绿洲油菜地土壤重金属元素的形态含量及比例特征进行了分析。结果表明:干旱区绿洲油菜地原状土壤中Cd和Pb分别主要以铁锰氧化物结合态及残渣态形式存在,而添加可溶性Cd和Pb后,两金属的主要赋存形态均为碳酸盐结合态。在任何浓度添加水平,可交换态Cd,Pb对外界浓度胁迫响应最大,残渣态响应最小。三种污染情景模式下油菜根际土壤中Cd,Pb形态拟合方程及生物活性系数的对比分析表明:两金属的互作对各元素活性的影响为:Pb的加入抑制Cd的土壤活性,而Cd的共存则促进Pb的土壤活性。     

干旱区绿洲土壤共存重金属Cd、Pb、Zn、Ni的吸收积累及形态分布实验研究

通过盆栽试验和室内分析初步研究了共存重金属Cd、Pb、Zn、Ni在干旱区绿洲土壤-芹菜系统中的吸收积累和形态变化特征。结果表明:Cd、Pb、Zn、Ni四种共存重金属元素在芹菜不同部位的吸收量均为根部地上部,累积率大小顺序依次为CdZnNiPb;供试绿洲土壤原状土中Pb、Zn、Ni均以稳定的残渣态为主要存在形态,Cd以铁锰氧化态为主要存在形态,随着重金属元素添加量的增加,土壤中的Cd主要以碳酸盐态存在,Pb主要以碳酸盐态和铁锰氧化态存在,而Zn和Ni主要以铁锰氧化态存在;逐步回归分析表明,干旱区绿洲土壤中Cd的可交换态对芹菜地上部Cd含量的贡献最大,Ni的铁锰氧化态对芹菜根部Ni含量的贡献最大,而对芹菜地上部和根部吸收Pb和Zn量贡献最大的形态分别为Pb和Zn的可交换态。     

干旱区绿洲土壤中Cd、Pb、Zn、Ni复合污染对芹菜的影响及其富集迁移规律

通过盆栽试验和室内分析初步研究了干旱区绿洲土壤中Cd、Pb、Zn、Ni复合污染对芹菜生长的影响及重金属在芹菜体内的富集迁移规律。结果表明:随着外源重金属添加量的增加,芹菜的生长受到明显抑制。根据多元回归分析和偏相关分析,芹菜地上部和根部吸收Pb量分别与外源添加Pb、Zn、Ni量和Cd、Pb、Zn、Ni量达到极显著相关,其中土壤Zn含量的增加极显著的降低了芹菜地上部和根部对Pb的吸收。芹菜地上部及根部对Cd、Pb、Zn、Ni四种元素的富集系数大小顺序均为:Cd>Zn>Ni>Pb,且根部对四种重金属元素的富集能力显著大于地上部。Cd在芹菜中的平均迁移能力最强,Zn、Ni次之,Pb的迁移能力最弱。     

低分子量有机酸对二氯喹啉酸在土壤中吸附-解吸的影响

采用高效液相色谱仪及批量平衡试验方法,研究了乙酸、苹果酸、酒石酸、草酸、丁二酸和柠檬酸6种低分子量有机酸对麻沙泥和第四纪红土红壤吸附-解吸二氯喹啉酸的影响。结果表明:低分子量有机酸可推迟二氯喹啉酸在土壤中的吸附平衡时间,其吸附动力学过程可用准二级动力学方程描述。Linear和Freundlich方程能较好地拟合二氯喹啉酸在供试两种土壤中的吸附等温线;二氯喹啉酸在麻沙泥中的吸附能力(lg Kf值)从大到小依次为苹果酸柠檬酸草酸=乙酸丁二酸酒石酸,在第四纪红土红壤中为苹果酸丁二酸乙酸草酸柠檬酸酒石酸;低分子量有机酸浓度对二氯喹啉酸解吸的影响因有机酸种类和供试土壤的不同而差异较大,6种供试有机酸均促进了第四纪红土红壤对二氯喹啉酸的解吸,且其解吸率均明显高于麻沙泥对二氯喹啉酸的解吸率,但在麻沙泥中呈现不同的影响模式。     

生物炭对苏丹草吸收Cd、Pb的影响

为了探讨生物炭添加对苏丹草吸收Cd、Pb的影响,在灰漠土中外源添加不同浓度的Cd和Pb,在此基础上添加5~20g/kg生物炭,通过盆栽试验研究生物炭对Cd、Pb在苏丹草中的分布及累积特征的影响。结果表明:添加生物炭和低浓度重金属能促进苏丹草的生长,使根、茎、叶生物量显著增加(P<0.05),但高浓度重金属的添加会抑制苏丹草的生长。在低中浓度重金属Cd-Pb的处理下,添加5~20g/kg生物炭,Cd在苏丹草根、茎、叶中质量分数、富集系数、转移系数及地上部分的累积量均呈降低趋势,Pb则相反。说明了生物炭的添加能抑制低中浓度Cd在苏丹草中的迁移。在高浓度重金属Cd-Pb的作用下添加生物炭对Cd和Pb在苏丹草中迁移均有抑制作用。     

城市污泥熟化前后对Cd2+的吸附解吸特征

研究了城市生污泥和熟污泥对Cd的吸附解吸特性及其差异性.结果表明:生污泥和熟污泥对Cd2+的吸附量均随着平衡溶液中Cd2+离子浓度的增加而增加,但增加速率渐趋缓慢,生污泥对Cd2+的吸附量小于熟污泥,Freundlich型吸附等温线方程是描述生污泥或熟污泥对Cd2+的吸附量和Cd2+平衡浓度之间关系的最佳模型.生污泥和熟污泥的解吸率均随着Cd2+初始浓度的升高而持续增大,但增加速率整体上在下降,生污泥的解吸率略高于熟污泥.生污泥和熟污泥对Cd2+的解吸量均随着污泥中Cd2+吸附量的增加而增加,且二者呈显著正相关关系(P ＜0.001).     

嗪吡嘧磺隆在土壤中的吸附特性及其吸附过程模型的建立

磺酰脲类除草剂是应用较为广泛的农药之一,其在土壤中迁移、降解、转化和滞留等多个过程受其吸附、解吸行为的影响。本文以嗪吡嘧磺隆为研究对象,采用批量平衡法研究了其在8种不同类型土壤中的吸附、解吸附行为。结果表明:嗪吡嘧磺隆与土壤溶液接触4 h内为快速吸附阶段。Freundlich模型可较好地拟合嗪吡嘧磺隆在土壤中的等温吸附解吸过程,相关系数 (r) 值在0.9584~0.9973之间。8种土壤对嗪吡嘧磺隆的吸附能力均为弱,吸附常数 (K_f-ads) 在0.281~3.515之间。其中,以黑龙江白浆土对嗪吡嘧磺隆的吸附能力最强,且远高于其他土壤。除广西赤红壤外,嗪吡嘧磺隆在其他7种类型土壤中的滞后系数 (H) 均小于1,解吸过程存在滞后现象,存在潜在环境风险。单因素试验结果表明,嗪吡嘧磺隆在土壤中的吸附行为受腐殖酸的影响极显著 (P＜0.01),受pH值和Mn2 + 的影响显著 (P＜0.05),受高岭土和稻壳生物炭的影响不显著 (P＞0.05)。采用中心复合试验设计,建立了具有一定预测功能的嗪吡嘧磺隆在土壤中的吸附过程BP神经网络模型,并进行了验证,拟合结果较好。     

SOME PHYSICO-CHEMICAL INTERACTIONS OF PARAQUAT WITH SOIL ORGANIC MATERIALS AND MODEL COMPOUNDS

Summary. The adsorption equilibria of paraquat were investigated on a range of organic materials including an organic soil, various humic fractions of that soil, model polymers prepared by the oxidative coupling of benzoquinone, ion-exchange resins (Zeo-Karb 216 and 226) and a polystyrene resin (Amberlite XAD-2). Isotherms were prepared for adsorption on the H⁺ and on some of the Ca²⁺ saturated materials. Measurement of the counter-ion in solution at equilibrium, and correlation of the adsorption with exchange capacity for H⁺ adsorbents showed that ion exchange was the primary adsorption mechanism. Significant amounts of non-exchange adsorption were also detected, especially at low concentrations, but generally the results followed the Rothmund-Kornfeld isotherm equation fairly accurately. The Rothmund-Kornfeld plots for the Ga²⁺ forms were complicated by the hydrolysis by water of some of the exchange sites. Other types of isotherm equations were tested and found to be unsatisfactory.
Desorption of paraquat with HCl from organic soil preparations was less than expected, and the isotherms did not conform to the Rothmund-Kornfeld or to the mass action equations. The probable reasons for this behaviour arc discussed.
Quelques interactions physico-chimiques du paraquat avec des matériaux de sol organique et des composés modèles
II. Adsorption, désorption et équilibre dans les suspensions aqueuses     

咪鲜胺及其制剂在六种水稻土中的吸附

研究了咪鲜胺(prochloraz)及其制剂施保克(Sportak,25%咪鲜胺乳油)在6种水稻土中的吸附行为和吸附机理。结果表明:咪鲜胺和施保克在水稻土中的吸附平衡时间为5~10 h,其吸附过程符合Freundlich吸附等温式;咪鲜胺和施保克在6种水稻土中有机质吸附常数(KOM)的平均值分别为 2 439和2 111,表明它们易被水稻土吸附,属难移动的物质,且吸附反应自由能的变化量均小于40 kJ/mol, 表现为物理吸附过程;吸附常数(Kf值)与土壤理化性质的相关性分析结果表明,咪鲜胺和施保克在土壤中的吸附主要受土壤有机质含量、阳离子交换量和粘粒含量的影响,并呈正相关;咪鲜胺在加工成制剂后,不但在土壤中的吸附量减少了,而且Kf值也下降了近1/3。     

三氟苯嘧啶在5种土壤中的吸附与解吸附行为

为研究三氟苯嘧啶的吸附-解吸附特性,采用振荡平衡法研究了三氟苯嘧啶在采集于吉林通化、江苏扬州、江西萍乡、广西南宁和海南海口等地的5种土壤中的吸附-解吸附行为及其环境影响因素。结果表明:三氟苯嘧啶在土壤中的吸附动力学符合Elovich模型,吸附和解吸附等温线符合Freundlich模型,吸附常数在1.886~7.626。温度的升高更有利于吸附,土壤对三氟苯嘧啶的吸附主要是物理吸附;随着溶液中pH值的升高,土壤对三氟苯嘧啶的吸附能力逐渐下降。除广西南宁黏壤土外,三氟苯嘧啶在5种土壤中的解吸附过程中存在滞后现象,不易在土壤中长期积累,具有一定的迁移特性。     

Copper and Zinc Competitive Adsorption: Desorption in Calcareous Soils

The behavior in competitive adsorption-desorption reactions of Cu and Zn was studied in four calcareous soils. Cu and Zn were added to the soil by Cu, Zn, and Cu+Zn sulfate solutions in a CaSO4 background. Soil sorption of these cations was described by equilibrium isotherms that fitted either Freundlich- or Langmuir type equations, although Cu desorption data fitted only Freundlich isotherms. Cu and Zn competition was quantified by distribution coefficients, Kd, relating cation distribution between soil and solute and by the competitive Langmuir equation. The competitive Langmuir equation was the better suited to describe the Cu-Zn competitive adsorption in these soils. Distribution coefficients presented lower values when both cations were present, decreasing when the Cu and Zn concentration in solution increased (decreasing soil affinity for these cations), thereby increasing their mobility through the soil. However, the distribution coefficient of specifically adsorbed Cu in equilibrium with cations extracted by a Mg (NO) solution increased with Cu concentration. Cu adsorption was more depres 3 se 2 d by Zn than Zn adsorption by Cu. The different behavior of Cu and Zn seems dependent on the percentage Ca (CO) and, to a lesser degree, on Cu and Zn organic matter complexes, free iro 3 n 2 content, and surface precipitation on oxides and carbonates.     

Adsorption–desorption of 2,4-D by hydroxy aluminium montmorillonite complexes

Adsorption–desorption characteristics of 2,4-dichlorophenoxyacetic acid (2,4-D) on pure montmorillonite and synthetic chlorite-like complexes [Al(OH)_x-montmorillonite complexes, obtained by coating montmorillonite surfaces with different amounts of Al(OH)_x] were investigated. The equilibrium adsorption of 2,4-D was described by both Langmuir and Freundlich type isotherms. The extent of adsorption as well as the type of interaction between adsorbate and adsorbent was affected by the nature of incubation buffer and the charge characteristics of supports. At pH 5·6 and in acetate buffer, 2,4-D was negatively adsorbed by montmorillonite and herbicide adsorption capacity increased with increasing amounts of Al(OH)_x species loaded on montmorillonite surfaces. When adsorption experiments were performed at the same pH but in phosphate buffer, strong reductions of both the amount of adsorbed pesticide and its affinity for the adsorbents were measured. Evidently, phosphate anions competed strongly with 2,4-D anions for the sorption site on chlorite-like complexes. Furthermore, desorption tests revealed that a large amount (about 60%) of the pesticide was firmly bound to the clay and was not removed even after repeated washings or 24 h exposure to desorption solution. Both electrostatic interactions between the negative COO^- moieties of 2,4-D and the positive sites on clays, and ligand exchanges of COO^- groups with -OH or water at the clay surface were probably involved in the adsorption process. ©1997 SCI