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1.
不同性质铁铝土对砷酸根吸附特性的比较研究 总被引：4，自引：0，他引：4
采用批平衡法研究了8种不同性质铁铝土对砷酸根的吸附特性,分别运用Langmuir单表面方程和Langmuir双表面方程对等温吸附数据进行拟合,以较优拟合方程求出土壤对砷的最大吸附量,并采用简单线性相关分析法探讨土壤性质对砷吸附能力的影响。结果显示,铁铝土对砷吸附强烈,吸附等温线均为非线性。双表面方程对吸附等温线的拟合效果优于单表面方程。采用双表面方程预测的吸附量和实测值的决定系数(0.935～0.978)大于采用单表面方程预测获得的决定系数(0.989～0.998)。土壤的砷吸附能力可采用高能表面和低能表面两种吸附位点进行解释。采集于云南昆明的砂页岩母质发育的红壤具有最强的砷吸附能力,根据Langmuir双表面方程计算的最大吸附量为3 498 mg kg-1。土壤的砷吸附能力受到土壤中游离氧化铁、全铝、全铁、黏粒和全磷含量的显著影响,最大吸附量与这几种土壤组成与性质因子呈显著正相关关系。 相似文献
2.
The increasing mobility of arsenate will increase its leachingpotential to groundwater and uptake by plants. The mobility ofarsenate in soils is related to the competitive adsorption with other substances. The effect of organic substances on the adsorption of arsenate by soils was evaluated using the water extract of compost (WEC) as a complex anion source in a batch experiment. Two calcareous slate alluvial soils, Chiwulan andShuipientou, with higher arsenic contents of 23.7 and 12.9 mg kg-1, respectively, were used. The Langmuir equation has been used to describe successfully the As adsorption isotherm for the two soils. The maximum adsorption of As was 6.098 and 4.785 μmol g-1 for Chiwulan and Shuipientou soils, respectively. There was competitive adsorption for binding siteson the soils between arsenate oxyanions and organic anions derived from the dissolved organic carbon (DOC) of WEC. Differentcritical pH values were for arsenate addition related to arsenateadsorption on both soils in the absence of DOC of WEC but not inthe presence of DOC of WEC. The soil properties related to arsenate adsorption by the two soils may govern the critical pH values. 相似文献
3.
Adsorption of arsenic onto soil was investigated as a means of understanding arsenic-induced release of phosphate. In batch adsorption experiments As adsorption was accompanied by P desorption. At low As additions, the ratio As adsorbed: P desorbed remained constant. At higher As additions, P desorptionreached a maximum while As adsorption continued to increase. The P desorption maximum coincided with an increase in pH.Barley plants were grown on soils spiked with arsenate(0–360 mg As kg-1) to investigate the effect on plant growth and P uptake. As arsenic concentration increased, above ground plant yield decreased and the plants showed symptoms typical of As toxicity and P deficiency. At low As additions to the soil, uptake of As and P by barley increased. At higher As additions P uptake decreased. It is argued that this was due to the change in As:P ratio in the soil solution. It is concluded that input of arsenic to thesoil could mobilise phosphate. Crop yield is likely to be affected, either due to reduced phosphate availability at low arsenic additions or arsenic toxicity at higher additions. 相似文献
4.
《Communications in Soil Science and Plant Analysis》2012,43(19-20):3015-3022
A laboratory experiment studied the adsorption of arsenate on coarse loamy mixed hyperthermic Fluventic Haplustept soil of Punjab to serve as cheap materials for removal of arsenic (As) from water with elevated As concentration. The arsenate adsorptions onto soil and soil + iron fillings are described by a two‐region Langmuir isotherm equation; that is, the plots showed two distinct linear portions. The bonding energy and adsorption maxima for arsenate adsorption by soil increased slightly at higher equilibrium temperature of 305 K relative to 280 K in the Langmuir plot for region I but followed an appreciative decline in both parameters for region II. The addition of iron fillings enhanced the adsorption maxima of arsenic soils by 2.5‐fold because of physical adsorption and 4.44‐fold because of chemisorptions or precipitation at weak and strong As concentrations, respectively, in soil–water equilibrated systems. Thus, the results of the present investigation suggest that water withdrawn from shallow aquifer containing elevated As concentrations should be equilibrated with mixtures of soil and iron fillings for removal of As. After an equilibration period, separation of water by decantation or filtration could be used for drinking purposes for humans and domestic animals. 相似文献
5.
不同类型土壤对汞和砷的吸附解吸特征研究 总被引：9，自引：0，他引：9
为了探明不同类型土壤对重金属汞和砷吸附、解吸的影响,以性质差异显著的红壤、黑土和潮土为供试土壤,采用批量平衡法,研究了Hg(Ⅱ)和As(Ⅴ)在不同土壤中的吸附-解吸行为。结果表明:(1)Freundlich方程和Langmuir方程均能较好地拟合这3种土壤对Hg(Ⅱ)和As(Ⅴ)的吸附,其中Hg(Ⅱ)的最大吸附量分别为451.33、1699.46和1635.21mg/kg,大小顺序为黑土>潮土>红壤,相关系数(R2)在0.8533～0.9911之间;As(Ⅴ)的最大吸附量分别为818.44、561.87和112.77mg/kg,大小顺序为:红壤>黑土>潮土,相关系数(R2)在0.9223～0.9949之间;而线性方程则不能较好地拟合这3种土壤对Hg(Ⅱ)和As(Ⅴ)的等温吸附。(2)Hg(Ⅱ)和As(Ⅴ)的解吸量随Hg(Ⅱ)和As(Ⅴ)吸附量的增加而增加,两者之间呈显著或极显著的线性正相关,Hg(Ⅱ)的相关系数(R2)分别为0.8668**、0.8971**、0.9969**,As(Ⅴ)的相关系数(R2)分别为0.9987**、0.9964**、0.9858**。研究结果对于探明土壤中汞和砷的环境行为具有重要意义。 相似文献
6.
磷对土壤As(V)固定与活化的影响 总被引：12，自引：0，他引：12
P和As的化学性质相近,在土壤中存在竞争吸附的关系,因而土壤中P浓度增加可能会影响As的固定和活化。本文通过等温吸附和浸提实验,模拟施P对黄棕壤中As固定和活化的影响。实验结果表明,提高溶液P浓度能够减少土壤对As的吸持能力,并增加As从土壤中的解吸量。在P浓度较低的情况下,这种影响尤其显著,As的解吸量与P浓度成极显著的线性相关关系。因此,不能忽视施用P肥对土壤As活化和迁移的影响。持续增加溶液的P浓度时,这种影响的程度逐渐减弱,可能与土壤中存在不同类型的吸附位有关。 相似文献
7.
Adsorption and desorption of exogenous rare earth elements (REE) in soils were studied.Results showed that soils had strong adsorbability for REE and the rate of adsorption of REE was over 95% of the added REE in these tests.The characteristics of adsorption isotherms corresponded well with the both Freundlich and Temkin equations,but deviated from the Langmuir equation.The adsorption of REE tended to increase with the rising of soil pH.A sequential extraction method used for studing the desorption and distribution of REE sorbed in soils are also discussed. 相似文献
8.
Silicon (Si) reduces arsenic (As) levels in rice shoot and grain. However, the underlying mechanisms remain unclear. In this study, we examined the effect of Si application to three rice paddy soils on the dynamics of Si, iron (Fe), phosphorus (P), and As in the soil solution, As accumulation in rice straw, flag leaf, husk, brown rice, and polished rice, and on As speciation in polished rice. Silicon application to soil increased the concentrations of Si, Fe, As, and P in the soil solution, while the redox potential was unaffected. Arsenic concentrations of straw, flag leaf, and husk were reduced by half by Si application, while As concentrations of brown and polished rice were decreased by 22%. The main As species in polished rice was arsenite, As(III), with a fraction of 70%, followed by dimethylarsinic acid (DMA) and arsenate, As(V), with 24% and 6%, respectively. Silicon application to the soil did not affect DMA or As(V) concentration of polished rice, while the As(III) concentration was reduced by 33%. These results confirm that Si reduces As(III) uptake and translocation into the shoot. Furthermore, data indicate that decrease of As concentration of polished rice is due to decreased As(III) transport into grain. Possible underlying mechanisms are discussed. 相似文献
9.
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。 相似文献
10.
The aim of the study was to evaluate effects of mobile and immobile water and diffusion‐limited transport on the binding and release of ions in soils. The desorption and leaching of calcium in a humic layer of a densely rooted acid forest soil under a beech stand was studied in laboratory experiments by leaching soil columns with a desorption solution and recycling the leachate through the columns. Radioactive tracers were added and monitored in the leachate to evaluate desorption and leaching characteristics of the soil. Parallel experiments were conducted with chloride and calcium to determine transport and desorption parameters independently. The experimental data were then analysed with a transport model, taking into account effects of mobile and immobile soil water fractions, and in the case of calcium assuming an equilibrium Langmuir adsorption isotherm. The transport was highly dependent on the mobility of the soil water, and in particular the fraction of the soil water to which the chemical was confined as a result of ionic properties. For chloride an excluded soil water phase had to be taken into account to explain the experimental findings. Immobile or mobile water and solute transfer and transport properties were not sufficient to explain non‐equilibrium effects in the adsorption reactions. Desorption curves agreed with results from batch experiments, provided the leaching experiments were done in such a way that equilibration between the soil solution and the solid matrix adsorption sites was reached, otherwise desorption was delayed and the calculated isotherms do not represent actual equilibrium adsorption–desorption conditions. 相似文献
11.
研究了四川盆地丘陵区典型水田和旱地土壤对磷的吸附与解吸特征,并讨论了吸附-解吸参数与土壤基本理化性质的关系。结果表明,不同pH的农田土壤对磷的吸附和解吸均存在显著差异,土壤对磷的吸持能力表现为中性土壤〉酸性土壤〉石灰性土壤,中性有利于土壤吸附磷;水稻土对磷的最大吸附容量（Qm）和最大缓冲容量（MBC）高于紫色土,而临界平衡磷浓度（EPC0）和解吸率（b）低于紫色土。农田土壤对磷的吸附与解吸参数还受土壤理化性质的影响,Qm和MBC与有机质含量、无定形铁（Fe-ox）含量呈极显著正相关（P〈0.01,n=6）;吸附常数（K）与有机磷含量呈显著负相关（P〈0.05,n=6）;EPC0与土壤pH、CaCO3含量呈显著负相关,与有机磷含量呈显著正相关（P〈0.05,n=6）;b与Fe-ox含量呈显著负相关（P〈0.05,n=6）。 相似文献
12.
Ribeiro Emerson S. Dias Luiz E. Alvarez Víctor Hugo V. Lynch Leila S. 《Journal of Soils and Sediments》2004,4(3):163-169
Background Arsenic (As) availability in natural environment is related to the element’s adsorption and desorption processes in soils.
Total As is better related to available As in temperate soils than in tropical soils. In tropical soils, total As is not very
significant in terms of availability, therefore justifying the necessity for studies into As dynamics. Knowledge of As dynamics
in soil as well as development of new analytical methodologies involving tropical soils are insufficient and necessary for
future mitigation projects.
Objective The objectives of this study were: (1) To adjust methodologies which may assist in understanding arsenate dynamics in tropical
soils and substrates; (2) To evaluate the adsorption and desorption of arsenate in soils and substrate samples, and to find
a minimum value of arsenate available in soil which is lethal to sorghum plants.
Material and Methods Samples of three soils from Minas Gerais State (YL, RYL, and CS) and two sulfide substrates of gold mining (B1 and B2) were
used in the assays. All the material was physically and chemically characterized. Remaining As (As-rem) and remaining P (P-rem)
of each material, along with MACP and MACAs (using the Langmuir isotherms), were obtained. After agitation to obtain MACP and MACAs, arsenate was extracted by anionic resin and Mehlich-III to evaluate arsenate desorption of the material retained on the
filter paper. Subsequently, arsenate desorption curves for the different materials were obtained, and arsenate availability
was determined through a bioassay with sorghum plants. Samples of soils and substrate B1 were incubated with six levels of
As doses. Plants were grown under greenhouse conditions for 30 days. The plants were then harvested, dried and weighed. Available
As in the soils and substrate was determined by Mehlich-III.
Results and Discussions As-rem level decreased from YL (sandy) to RYL (clayey) soil samples, which always showed lower values than P-rem. Among the
soils and substrates evaluated, RYL showed the highest MACAs and MACP, followed by CS, YL and Bl. The results were in accordance with the values observed for As-rem and P-rem and confirm the
idea that the ability of the assayed materials to remove As from the soil/substrate solution is higher than the ability to
remove P. On the other hand, the binding energy (a) between soil/substrate and As is weaker than the binding energy of P.
Given the fact that the studied soils present a real ability to remove As from the solution, only a small part of As would
be unavailable considering MACAs as a reference. As-Mehlich-III values were higher than As-resin for substrate Bl. Mehlich-III seemed to be more appropriate
to extract labile forms of arsenate in substrate B1 as well as in the soils. Available As by Mehlich-III (26.9 mg/dm3) was considered a reference of As LCL to sorghum plants. CC50 was sensitive to the buffering capacity of each soil, showing
values varying from 1.34 mg/dm3 As (clay soil with lower As-rem) to 12.31 mg/dm3 As (sandy soil with higher As-rem).
Conclusions The adaptation of the As-rem and MACAs methodologies was satisfactory and of great value in the study of adsorption, desorption and As availability for soils and
mining substrate. Mehlich-III was also satisfactory to estimate available As and was sensitive to soil buffering capacity.
Nevertheless, resin can also be used as an alternative. MACAs varied among soils and was higher than MACp. However, As showed higher lability than P. Using Mehlich-III, we determined the value corresponding to CC50 that showed
a good reference of toxicity to available As.
Outlook The environmental implications of the As behavior are quite serious. Beside the fact that arsenate is removed very fast from
the soil solution, an anthropogenic input of the element, being part of the soil quantity factor, may remain in a reversible
form for a long time. As may therefore return to the soil solution and becomes available to plants, animals and the entire
environment. Considering that CC50 is the maximum contents of available As the environment can tolerate to allow some vegetal
biomass production, the maximum capacity of As immobilization in each soil is reduced when compared to the soils’ MACAs values. Therefore, the maximum and safe values of reference to be used in the evaluation of incidental discharge of the element
in soils must be reduced. 相似文献
13.
Arsenic has recently received increasing attention due to its high toxicity and to the possible risks for human and environmental health associated with As-polluted soils. The present work deals with the kinetics and reversibility of As sorption by Fe-oxide-coated sand (IOCS) and soils with different chemical and physical characteristics. Soils and IOCS were equilibrated for five different periods of time with solutions containing As (III) and/or (V) in order to study the kinetics of As adsorption. After 1, 10 and 30 days of equilibration soils and IOCS were sequentially extracted to assess the effect of aging on the binding forms of As. The kinetics of arsenite and arsenate adsorption varied among the soils as a result of differential soil characteristics. The conversion of As to less mobile forms was demonstrated using a sequential extraction. The amount of As extracted with weaker extractants decreased with time whereas the amount of As in more recalcitrant fractions increased. This conversion is expected to render As less mobile and toxic with time after addition to the soil. 相似文献
14.
《Communications in Soil Science and Plant Analysis》2012,43(1):108-121
Cadmium (Cd) sorption and desorption characteristics by Alfisols from different land uses were examined, and the relationships between soil and sorption/desorption characteristics were investigated. Adsorption studies were done using Cd concentrations (0–100 mg Cd kg?1) in 0.01 M CaCl2. The Cd sorbed by the soils was then subjected to two desorption runs. The soils' adsorption conformed to Freundlich and Langmuir equations. The amount of Cd sorbed by the soils varied. Two desorption runs detached more than 95% of sorbed Cd, but the first accounted for more than 80% of the total. Desorption of Cd in degraded soils was more than in soils from other land uses. The amount of Cd desorbed correlated with amount applied (r = 0.90??), solution concentration (r = 0.83??), and amount sorbed (r = 0.70??). A positive relationship exists between the adsorption maxima of the soils and soil organic matter (r = 0.13, p = 0.87). The relationship between amount of Cd desorbed and sorbed is quadratic for all the soil. 相似文献
15.
《Communications in Soil Science and Plant Analysis》2012,43(17-18):2800-2815
Lead arsenate has been used as pesticide. Flooding soils contaminated by lead arsenate could increase plant arsenic and lead and become a human health risk. The objective was to determine the effects of flooding of lead‐arsenate soils on rice grain yield and arsenic and lead accumulation. Bagstown and Chashmont soils with high levels of arsenic and lead were planted with rice in the greenhouse under flooded and nonflooded conditions. Flooding reduced grain yield and increased grain arsenic concentration on both soils. Grain lead decreased with flooding for the Bagstown soil but increased for the Chashmont. Arsenic and lead concentrations in the straw were more than in grain. Grain arsenic and lead levels observed would not be expected to become a human health risk. However, bioavailability studies are needed. The high arsenic and lead in the straw may indirectly become a human health risk because rice straw is used for livestock feed and bedding. 相似文献
16.
Adsorption of sulphate was studied on eight West Indian soils. Adsorption was dependent on concentration for all the soils studied. At low concentrations of dissolved sulphate, the amount adsorbed was in accordance with the Langmuir equation. At higher concentrations this relationship broke down and it is postulated that this is due to differing adsorption sites.In desorption studies, the amount of sulphate released decreased with each successive extraction. Only 32.7% and 76.4% of the initially adsorbed sulphate was recovered in four KH2PO4 extractions from Montserrat clay and Montreal sandy loam, respectively. This is ascribed to the different properties of the two soils.Sulphate adsorption was related to the percentage of NaOH-extractable aluminium in the soil. 相似文献
17.
Shuzhen Zhang Wei Li Xiao-Quan Shan Anxiang Lu Peijiang Zhou 《Water, air, and soil pollution》2005,167(1-4):111-122
Low-molecular-weight-organic-anions (LMWOAs) are important exudates of plants and may influence the mobility and bioavailability of metals or metalloids. In the present study the effects of selected LMWOAs, citrate, malate and oxalate, on the release of arsenite (As(III)) and arsenate (As(V)) in a contaminated soil were investigated. The organic anions have significant influence upon the release of arsenic from the soil, and a linear relationship exits between the released arsenic and the concentration of LMWOAs in the extractants. pH effects on the arsenite and arsenate adsorption were not significant over the range from 3 to 7. The amounts of arsenite and arsenate released were significantly correlated with the release of Fe, Mn and Al, suggesting that arsenic was mainly released from Fe-, Mn- and Al-oxides or hydroxides in soil. The ratio of released arsenite to arsenate was not influenced by LMWOAs. 相似文献
18.
本文讨论我国几种主要土壤胶体的NH4+吸附特征。土壤胶体对NH4+的吸附符合两种表面Langmuir方程。土壤胶体对NH4+的结合能力强弱顺序是:黄棕壤>黑土、(土娄)土>红壤>砖红壤,而NH4+的解吸率大小顺序与此相反。Langmuir吸附方程参数K1与土壤胶体的粘粒矿物组成有关,并与土壤胶体对NH4+的相对偏好性(A值)呈正相关。Langmuir参数(M1+M2)与土壤胶体的CEC呈正相关,去有机质(OM.)前后△K1与△OM.呈反相关。去有机质可增加土壤胶体对NH4+的偏好性。土壤胶体的NH4+吸附和解吸特征决定于其组成和表面性质,并受有机无机复合作用的影响。永久电荷吸附位对NH4+的偏好性较强,而可变电荷吸附位则较弱。 相似文献
19.
pH对砖红壤和黄棕壤Cu~(2+)吸附与解吸的影响 总被引：3，自引：0，他引：3
对砖红壤和黄棕壤在不同浓度、不同pH下吸附和解吸Cu2+进行了测定。结果表明, 2种土壤Cu2+吸附量均随平衡液中Cu2+浓度增加而增大,两者关系较好地符合Langmuir吸附方程。Cu2+吸附量随pH升高而增加,Cu2+分配系数的对数与pH呈极显著的线性正相关,吸附一个Cu2+所释放H+的平均数砖红壤(1. 19)大于黄棕壤(1. 01)。可解吸Cu2+的数量随pH升高和吸附Cu2+的数量增加而增加,在pH4~6下,黄棕壤吸附Cu2+及可解吸Cu2+的比例(平均为10. 5% )大于砖红壤(平均为3. 1% )。由此认为, 2种土壤吸附Cu2+虽以专性吸附为主,但砖红壤的表面吸附点位较少,专性吸附点位的比例较高,对Cu2+的亲和性或专性吸附性大于黄棕壤。 相似文献
20.
STUDIES ON SOIL COPPER 总被引：11，自引：0，他引：11
Adsorption isotherms were determined for the specific adsorption of copper by soils and soil constituents. Adsorption was found to conform to the Langmuir equation. The Langmuir constants, a (adsorption maximum) and b (bonding term), were calculated. Soils were found to have specific adsorption maxima at pH 5.5 of between 340 and 5780 μg g?1, and a multiple regression analysis revealed that organic matter and free manganese oxides were the dominant constituents contributing towards specific adsorption. Adsorption maxima for soil constituents followed the order manganese oxides > organic matter > iron oxides > clay minerals, which supported the findings for whole soils. The cation exchange capacities (non-specific adsorption) of the test soils were found to be far greater than the specific adsorption maxima. However, evidence suggests that, for the relatively small amounts of copper normally present in soils, specific adsorption is the more important process in controlling the concentration of copper in the soil solution. 相似文献