土壤镉吸附的研究进展

综述了土壤镉吸附的机理和土壤pH、有机质含量、粘粒矿物类型及含量、土壤溶液中竞争性阳离子、共存阴离子、土壤温度等土壤性质对土壤镉吸附的影响；总结了土壤镉的吸附量随土壤pH增加、温度升高及有机质、铁锰氧化物和粘土矿物含量增加而增加的机理；竞争性阳离子的存在抑制镉的吸附，土壤溶液中共存阴离子对镉吸附的影响取决于阴离子种类和土壤类型。     

Phosphate desorption from flooded and reoxidized soils as compared with adsorption characteristics

Abstract

The purpose of this study was to show how phosphorus (P) desorption can bring further information to what is inferred from adsorption experiments. A simple calculation procedure is proposed to predict the P amount that would be desorbed by washing with salt solution if adsorption was completely reversible. Consequently, the interpretation of P desorption can focus on the irreversible part of adsorption. This approach is applied to samples of acid sulfate soil from Vietnam that have been submerged for different periods of time, at 20°C and 30°C, and also to samples that were reoxidized after flooding. Phosphate desorption linearly increases with P concentration in solution and exponentially decreases with increasing adsorption capacity as expressed by the Freundlich coefficient of adsorption isotherms. These two types of relationships are correctly predicted by our calculation procedure. As far as reversibility is concerned, we find that with respect to calculated desorption, the proportion of irreversible adsorption greatly differ according to treatments. In relative terms, adsorption reversibility is lowest in the reoxidized soils and highest in the wet soils incubated at 30°C. This is related to the type and crystallinity of Fe‐oxihydroxides and consequent differences in P‐bonding energies.     

硫酸盐对锌和镉在可变电荷土壤上吸附的影响

SO4^2- and Zn^2 or Cd^2 were added to three variable charge soils in different sequences.In one sequence sulfate was added first ,and in the other,Zn^2 or Cd^2 first.The addition of sulfate to the system invariably caused an increase in adsorption of the heavy metal added,with the effect more remarkable whn the soil reacted with the sulfate prior to the metal.the shift in pH50 for both Zn and Cd adsorption was aslo comparatively larger in the first sequence of reactions .It was suggested that the increase in negative charge density and the resultant negative potential of the soil were the primary cause of the pronounced effect of sulfate on adsorption of Zn or Cd,and the formaiton of the ternary surface complex-S-SO4-M might also play a role in the effect.     

Organic matter as an influencing factor on copper and cadmium adsorption by soils

Soil organic matter influence on Langmuir isotherms for Cu and Cd in four Italian soils of different pedogenetic origin was investigated. Adsorption processes were carried out either on the whole soils or on soils after destruction of organic matter. Organic matter removal produced a noteworthy decrease of Cu adsorption contrasted by a smaller decrease or even a slight increase of Cd adsorption. Addition of increasing amounts of Cu on soil previously enriched with Cd did not significantly change the Cu adsorption while a rather different pattern was observed when increasing quantities of Cd were adsorbed on the same soil after Cu enrichment. In this case Cu already present in the soil reduced the amount of Cd adsorbed. These findings suggest that the differences found in the adsorption process of such metals primarily depend on the different chelating effectiveness of soil organic matter in the respect to Cu and Cd.     

不同土壤对Cr吸附的动力学特征

该文采用振荡平衡法比较了来自中国15 个省区16 种土壤对Cr（VI）的吸附及其动力学特性,并探讨了土壤pH值、阳离子交换量、黏粒含量和有机质对Cr（VI）吸附及其动力学参数的影响。结果表明：具有较低土壤pH值和较高物理黏粒含量的土壤对Cr（VI）具有较大的表观吸附量,而土壤阳离子交换量和有机质因素对土壤Cr（VI）的表观吸附量影响较小。酸性土壤对Cr（VI）吸附能力较强,可以采用一级动力学方程和抛物线方程描述Cr（VI）在酸性土壤中的动力学行为,且土壤的表观吸附速率和平衡时的吸附量与土壤的pH值呈显著（p＜0.05）负相关关系,而与物理黏粒含量呈显著（p＜0.01）正相关关系;而碱性土壤对Cr（VI）吸附能力较小,很难用动力学方程描述其吸附动力学特性。可见,土壤pH值不仅影响土壤对Cr（VI）的表观吸附量,并且对Cr（VI）表观吸附动力学特征产生了较大影响。     

不同老化方法对生物炭表面特征及镉吸附能力的影响

为明确不同自然环境过程（氧化还原、降雨、光照）对生物炭的老化作用及其对重金属吸附能力的影响,该研究以不同温度（200、500 °C）和气氛（O₂、N₂）热解的小麦秸秆生物炭为研究对象,采用化学氧化、干湿交替、紫外光照氧化3种人工老化方法模拟生物炭在自然环境中的老化过程,并分析老化作用对生物炭理化性质及镉（Cd）吸附能力的影响。结果表明：与初始生物炭相比,老化作用使生物炭表面破碎,孔隙结构增多,提高了生物炭比表面积。干湿交替老化使低温生物炭的比表面积增大0.85倍,而经过化学氧化后的低温生物炭、高温生物炭比表面积分别增大8.81、0.37倍。老化过程使生物炭的官能团种类减少,且含氧官能团数量发生不同程度的变化,其中化学氧化使羧基、内酯基等含氧官能团增多,而干湿交替及紫外光照老化主要引起含氧官能团数量的减少。此外,热重分析结果表明化学氧化使低温生物炭热稳定性降低,而所有老化后的高温生物炭热稳定性均增强。化学氧化、紫外光照、干湿交替3种老化处理均可提高两种生物炭的吸附能力,Cd²⁺吸附量分别提高498.95%~799.36%、436.10%~768.43%、35.53%~128.10%。因此,生物炭实际应用时需综合考虑其环境过程、特性变化以及目标污染物种类,以促进生物炭环境应用的长远发展。     

The nickel uptake from different soils and its prediction by chemical extractions

The uptake of Ni by 13 plant species was investigated from two soil types containing Ni in different concentrations and forms. Absorption was highest from Nicl₂, less from Ni containing sewage sludge or industrial filter dust, and least from a soil containing geogcnic Ni. The 13 species grown can be classified into four groups differing in Ni uptake and toxicity. The Ni contents in grain and in storage organs were larger than in the vegetative plant parts. The highest Ni contents were found in the roots. Plants grown in pots absorbed more Ni than from the same soils in the field. During consecutive years the Ni availability did not decrease. Only soil extractions with unbuffered salt solutions reflected the availability of pollution-derived Ni sufficiently well.     

Extractors for barium,cadmium, copper,nickel, and zinc in tropical soils

ABSTRACT

The accumulation of potentially toxic elements (PTEs) in the soil can pose risks to human health, and precise risk assessment dealing with the production and consumption of plants is required. The 0.43 M of nitric acid (HNO?) solution was suggested by the International Organization for Standardization for reactive fraction of PTEs in the soil. The efficiency of some extractors was evaluated in tropical soils. Contents of barium (Ba), cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) were extracted in accordance with the methods of Environmental Protection Agency (EPA) 3051A, Aqua Regia, Diethylenetriaminepentaacetic acid (DTPA), Mehlich-1, Mehlich-3, 0.43 M HNO? and 0.01 M of calcium chloride (CaCl?), and these contents correlated with the contents of PTEs in roots, shoots, and fruits of vegetables. Mehlich-3 had the highest correlation with Ni and Zn contents extracted by the plants. Contents extracted with 0.43 M HNO? had high correlation with the amounts extracted by DTPA and Mehlich-3, as well as with the amounts of PTEs accumulated by plants.     

不同土地利用方式土壤对铜、镉离子的吸附解吸特征

采用一次平衡法对Cu²⁺、Cd²⁺在城市及城郊农田、林地、草地3种土地利用方式土壤中的吸附解吸过程进行比较研究, 结果表明: Cu²⁺、Cd²⁺在3种土地利用方式土壤中的吸附量均随平衡液浓度的增加而增大, Cu²⁺、Cd²⁺在农田土壤上的吸附量均高于林地和草地土壤。分别用Langmuir和Freunlich两种等温吸附方程对吸附过程进行拟合, 3种土壤对Cu²⁺的吸附过程运用Langmuir方程拟合效果好, 而对Cd²⁺的吸附过程运用Freunlich方程拟合效果更好。Cu²⁺在3种土壤的解吸量大小顺序为农田>林地>草地, Cd²⁺在3种土壤的解吸量大小顺序为农田>草地>林地。两种离子在3种土壤中的动态吸附是个快速反应的过程, 随时间延长, 吸附反应趋于平衡。运用双常数函数方程和Elovich方程能较好地拟合重金属在土壤上的吸附动力学过程。Cu²⁺、Cd²⁺的吸附与土壤黏粒含量、有机质含量、CEC和pH均有关。     

不同母质发育的红壤性水稻土磷素吸附特性及其影响因素的研究

磷是作物生长发育所必需的营养元素,植物吸收利用的是土壤中的有效磷,土壤有效磷的消长取决于土壤磷素的收支状况,而其消长速度则与土壤性质有关[1]。不同质地土壤固相表面的吸附能力不同,因而影响了土壤溶渡中磷的浓度[2]。为确保土壤满足作物吸收所必需的最低磷溶液浓度,就需要对不同土壤固相的吸附性能进行研究。而水稻土常年以淹水和风干状态交替存在,因此水稻土中     

磷的吸附和表面电荷特征及其与华南地区某些土壤矿物的关系

The phosphate adsorption and surface charge characteristics of the tropical and subtropical soils derived from different parent materials in China were determined, and their relations to soil mineralogy were analysed. The results showed that all soil phosphate adsorption curves were well fitted by Freundlich equation and Langmuir equation. The maximum buffering capacity of P ranged from 66 to 9 880 mg kg^-1, with an increasing order of purple soil, skeletal soil, red soil, lateritic red soil, yellow soil and latosol; and the highest value was 149 times the lowest value, which indicated great differences among these soils in phosphate adsorption and supplying characteristics. The pH₀ (zero point of charge) values obtained by salt titration-potential titration varied from 3.03 to 5.49, and the highest value was found in the latosol derived from basalt whereas the lowest value was found in the purple soil. The correlation analysis indicated that the main minerals responsible for phosphate adsorption in the soils were gibbsite, amorphous iron oxide and kaolinite; and the pH₀ was mainly controlled by kaolinite, gibbsite and oxides.     

围海造田水稻土磷吸附动力学特征及其机理

沿海农田N、P排放是沿海湿地和近海水质污染源之一.研究围海造田土壤P化学行为对评价其水质污染风险,制定兼顾农业生产和环境保护P肥管理措施具有实际意义.本研究以浙江省慈溪市3个代表性时期(宋代,明代,现代)围海造田水稻田土壤为研究对象,研究了3种温度条件下(15℃,25℃,35℃)土壤P吸附动力学,并获得了其热力学参数....     

Fractionation of soil cadmium from some new zealand soils

Abstract

The concentrations and forms of soil cadmium (Cd) in 12 different New Zealand topsoils were investigated using a sequential fractionation procedure. Total soil Cd concentrations were low and ranged between 0.03 μg g^‐1 to 1.34 μg g^‐1 and were highly correlated with total soil phosphorus (r²=0.85, P<0.01). Results indicated that there was a wide range in the concentrations of Cd associated with individual soil fractions and large variations between soils. On average for all soils, the smallest proportion of Cd was in exchangeable forms, i.e., 3%, with 12% in the crystalline oxide fraction, 13% in the amorphous oxide fraction and the greatest proportion of Cd associated with the organic 34% and residual 38% fractions. There was evidence to show that a soil extractant which is commonly used to predict plant uptake of Cd from soils, i.e., 0.04 M ethylene diamine terra acetic acid (EDTA), extracts Cd from both exchangeable and organic forms of soil Cd.     

Phosphorus adsorption and desorption characteristics of different textural fluvo-aquic soils under long-term fertilization

Journal of Soils and Sediments - Phosphorus (P) fertilizer has been widely applied to improve crop yields in the North China Plain; however, most of applied P fertilizer is disabled due to the...     

Assessing cadmium availability of contaminated saline-sodic soils as influenced by biochar using the adsorption isotherm models

ABSTRACT

In arid/semi-arid regions, soil salinization, sodification and contamination by heavy metals (HMs) are the main constrains to plant growth, crop production and human health. Biochar can affect soil behaviors, e.g. adsorption of HMs that is one of the most effective techniques for reducing their bioavailability. Effect of three levels (0%, 2% and 4% wt) of sugarcane bagasse-derived biochar and two cadmium (Cd) levels (0 and 50 mg Cd kg^?1 soil as Cd(NO₃)₂) on Cd adsorption of saline, sodic, saline-sodic and normal soils were evaluated through studying adsorption isotherms. Six isotherm models were fitted to the data and the best model were chosen. The maximum Cd adsorption (694 mg kg^?1) obtained in sodic soils without biochar treatment. Cadmium removal decreased when dosage of the applied biochar increased. The minimum Cd removal obtained as 17%, 21%, and 23% in control, 2% and 4% biochar-treated saline soils, respectively. Biochar increased Cd adsorption in salt-affected soils. Increasing pH in soil solution after biochar addition resulted in an increase in net negative surface charge and the affinity of soil particles for Cd adsorption. Consequently, 2% biochar could ameliorate Cd contamination. However, Cd adsorption decreased when dosage of the applied biochar increased from 2% to 4%.     

Optimal isotherm model and explanatory characteristics associated with metal ion adsorption on humic acids isolated from forest soils

Journal of Soils and Sediments - Understanding the mechanisms of interaction between humic acids (HAs) and metal ions in soil media is essential for integrated environmental and agricultural...     

亚热带土壤不同矿物组分中铬的吸附

Safe application of chromium (Cr)-containing organic industrial wastes to soil requires considering the ability of the soil to adsorb Cr.In this study,the maximum Cr adsorption capacity was assessed for the bulk samples and their clay and iron-free clay fractions of four subtropical soils differing in mineralogy.To this end,the samples were supplied with Cr(Ⅲ) nitrate solutions at pH 4.5 or 5.5.The results of Cr(Ⅲ) adsorption fitted to a Freundlich equation and the adsorption capacity was positively correlated with soil organic matter and iron oxide contents.The clay fractions adsorbed more Cr per unit mass than the bulk soils and the iron-free clay fractions.The Cr(Ⅲ) adsorption capacity increased with increasing soil pH due to more charges on adsorbing surfaces.Our results suggest that the soils rich in organic matter and iron oxides and having a pH above 4.5 are suitable for application of Cr(Ⅲ)-loaded industrial wastes.     

Chemical pools of cadmium, nickel and zinc in polluted soils and some preliminary indications of their availability to plants

This study was conducted to determine the chemical distribution and plant availability of Cd, Zn and Ni in eight metal-polluted soils in southern Ontario, Canada. There were altogether 30 different soil samples because two of the soils had received various sewage sludge treatments. The soils were sequentially extracted with 1 m ammonium acetate to remove soluble plus exchangeable metals, with 0.125 m Cu(II) acetate to remove complexed metals, and with 1 m HNO₃ to dissolve chemisorbed or occluded metals and precipitates such as oxides and carbonates. Expressed as a percentage of the metal so extracted, exchangeable Cd and Zn and Ni; complexed Cd and Zn>Ni and Ni>Zn>Cd in the acid-soluble pool. With a few exceptions (soils with high organic matter content or low pH) at least 50 per cent of the extracted metal was in the acid-soluble pool. The percentage of metal complexed was significantly correlated with organic matter content. The percentage of metal in the acid-soluble fraction was significantly correlated with soil pH. Preliminary findings based on the results with two soils suggested that for Cd and Zn plant availability was correlated with the concentrations of exchangeable, complexed or acid-soluble pools of Cd and Zn.     

Boron adsorption characteristics of some acidic alluvial soils in relation to soil properties

Abstract

We investigated boron (B) adsorption characteristics for 16 acid alluvial soils as a function of equilibrium B concentration (0–80 μg/mL) and the effect of soil properties on such adsorption. The adsorption data for the soils could be described by Freundlich, Temkin, and BET isotherm equations over the entire concentration ranges studied, and by Langmuir and Eadie‐Hofstee equations only over a limited range. In general, the B adsorption capacity and the energy of retention of the soils calculated from different equations are low, the average Langmuir adsorption maxima and bonding energy constant being 21.47 μg/g and 0.113 mL/μg, respectively, making B susceptible to leaching losses. Simple and multiple regression analysis show that the adsorption capacities are significantly influenced by organic carbon (C), cation exchange capacity (CEC), and different forms of aluminium (Al) content in soils. The energy related constants are also influenced by the forms of Al in soils. Existence of significant correlations between constants obtained from different equations confirmed the adsorption characteristics of the soils.