共查询到19条相似文献,搜索用时 203 毫秒
1.
用模拟酸雨酸化浙江省3种主要类型土壤,研究了酸化土壤活性铝的溶出和铝的形态变化。结果表明:酸雨对强酸性土壤(pH<5)中活性铝的释出有一定促进作用,活性铝以A1 ̄(3-)离子为主。当土壤pH值>5时.活性铝以单聚羟基铝为主。酸化土壤中的活性铝主要是由土壤中固相的Al(OH)转化而来。 相似文献
2.
聚硅氯化铝(PASC)的形态分布及转化规律:Ⅱ.^27Al—NMR法研究PASC溶 … 总被引:8,自引:0,他引:8
采用^27Al-NMR法比较研究了PASC与PAC中铝的形态分布。实验结果表明,在PASC中,由于聚硅酸与铝水解聚合物产物间的相互作用,使得铝的水解聚合形态分布及转化情况发生了变化。在相同B值条件下,PASC中Al单和Al13的含量低于PAC中相应Al单和Al13的含量,而PASC中Al其它的含量大于PAC中Al其它的含量,其差值随着碱化度(B)和Al/Si摩尔比的减小而增大。 相似文献
3.
Al—Ferron逐时络合比色法研究PACS中铝的水解聚合形态 总被引:2,自引:1,他引:2
制备了碱化度及不同Al^3+/SO^2=4摩尔比的系列PACS,用Al-Ferron逐时络合比色法研究了铝的形态分布,考察了碱化度,Al^3=/SO^2=4摩尔比,稀释作用及pH值对铝的形态分布的影响。 相似文献
4.
5.
本文对Al-Ferron逐时络合比色法和^27Al-NMR法对PASC和PAC中铝的形态分布测定结果进行了对比分析的讨论。结果表明。在PAC中,Al13和Albh之间具有良好的对应关系。Al13/Alb比值为1.0左右。但对PASC而言,情况有所不同,在低碱化度(B)和低Al/Si摩尔比情况下,Al13和Alb之间的不存在对应关系,Al13和Alb比值远远小于1.0,随着B值和Al/Si摩尔比的升 相似文献
6.
土壤上铍的存在形态及提取研究 总被引:2,自引:0,他引:2
本文对三种不同类型土壤中铍的存在形态及提取进行了研究,并做了原土铍和外加铍形态提取对照试验,选择了各形态合适的提取剂,建立了土壤铍形态连续提取方法,对提取机理和形态分布规律进行了探讨。此外,还对土壤提取的有效铍与盆栽植物吸收铍量的相关性进行了初步研究。 相似文献
7.
聚硅氯化铝(PASC)的形态分布及转化规律:Ⅰ.Al—Ferron逐时络合比色?… 总被引:23,自引:2,他引:21
采用Al-Ferron逐时络合比色法比较研究了PASC与PAC中铝的形态分布及转化规律。实际结果表明,在PASC中,由于聚硅酸与铝水解聚合产物的相互作用,使得铝的水解聚合形态分布及转化情况发生了变化。 相似文献
8.
Al—Ferro络合比色动力学特征与聚合铝溶液形态 总被引:3,自引:0,他引:3
本文考察了Al-Ferron逐时络合比色反应的假一级动力学特征,并探讨了其动力学参数的变化规律与聚合铝溶液形态分布和转化间的关系。结果表明。「Alb」0与「Alb」间的差值大小值rOH的变化情况可反映Alb的具体组分分布的复杂程度;Kb值的变化一定程度上可为Al13是Alb 态的主要组分提供佐证。 相似文献
9.
10.
连续浸提技术测定土壤和沉积物中硒的形态 总被引:34,自引:0,他引:34
本文建立了土壤和沉积物中硒的形态分析方法,应用连续化学浸提技术将土壤和沉积物进行连续五次抽提,根据不同形态硒的溶解度,将土壤和沉积中的硒分为可溶态(水溶态)、可交换态及碳酸盐结合态、铁-锰氧化物结合态、有机物-硫化物结合态及元素态、残渣态五种结合形态。种形态硒分级浸提的相对标准偏差均小于4.0%,总回收率(即:五种形态和与总硒的比值)为93.2-94.4%。 相似文献
11.
Choi Ki Young Kim Suk Hyun Hong Gi Hoon Chon Hyo Taek 《Environmental geochemistry and health》2011,33(1):71-80
Mechanisms of natural attenuation of arsenic (As) by wetland plants may be classified by plant uptake and adsorption and/or co-precipitation by iron (oxy)hydroxide formed on the root surface of plants or in rhizosediment. A natural Cattail (Typha spp.) wetland impacted by tailings containing high levels of As from the Myungbong abandoned Au Mine, South Korea was selected, and the practical capability of this wetland to attenuate As was evaluated. The As concentrations in the plant tissues from the study wetland were several-fold higher than those from control wetland. SEM-EDX analyses demonstrated that iron plaques exist on the rhizome surface. Moreover, relatively high As contents bonded with hydrous iron oxides were found in the rhizosediments rather than in the bulk sediments. It was revealed through the leaching and sequential extraction analyses that As existed as more stable forms in the wetland sediment compared with adjacent paddy soil, which is also contaminated with As due to input of mine tailings. The As concentration ratios of extracted solution to sediment/soil represented that the wetland sediment showed significant lower values (10-fold) rather than the paddy soil with indicating high As stability. Also, As in the wetland sediment was predominantly bonded with residual phases on the basis of results from sequential extraction analysis. From these results, it is concluded that transformation of As contaminated agricultural field to wetland environment may be helpful for natural attenuation until active remediation action. 相似文献
12.
Mechanisms of natural attenuation of arsenic (As) by wetland plants may be classified by plant uptake and adsorption and/or co-precipitation by iron (oxy)hydroxide formed on the root surface of plants or in rhizosediment. A natural Cattail (Typha spp.) wetland impacted by tailings containing high levels of As from the Myungbong abandoned Au Mine, South Korea was selected, and the practical capability of this wetland to attenuate As was evaluated. The As concentrations in the plant tissues from the study wetland were several-fold higher than those from control wetland. SEM-EDX analyses demonstrated that iron plaques exist on the rhizome surface. Moreover, relatively high As contents bonded with hydrous iron oxides were found in the rhizosediments rather than in the bulk sediments. It was revealed through the leaching and sequential extraction analyses that As existed as more stable forms in the wetland sediment compared with adjacent paddy soil, which is also contaminated with As due to input of mine tailings. The As concentration ratios of extracted solution to sediment/soil represented that the wetland sediment showed significant lower values (10-fold) rather than the paddy soil with indicating high As stability. Also, As in the wetland sediment was predominantly bonded with residual phases on the basis of results from sequential extraction analysis. From these results, it is concluded that transformation of As contaminated agricultural field to wetland environment may be helpful for natural attenuation until active remediation action. 相似文献
13.
Drysdale M Ljung Bjorklund K Jamieson HE Weinstein P Cook A Watkins RT 《Environmental geochemistry and health》2012,34(2):279-288
Simulated lung fluids are solutions designed to mimic the composition of human interstitial lung fluid as closely as possible.
Analysis of mineral dusts using such solutions has been used to evaluate the respiratory bioaccessibility of various elements
for which solubility in the lungs is a primary determinant of reactivity. The objective of this study was to employ simulated
lung fluid analysis to investigate the respiratory bioaccessibility of nickel in soils. Current occupational guidelines in
Australia regulate nickel compounds in terms of water solubility, though this may not be an accurate estimation of the total
nickel that will dissociate in the lungs. Surface soils were collected from the city of Kalgoorlie in Western Australia, the
site of an operational nickel smelter and metal mining activities. The fraction of the samples less than 10 μm was extracted
from the soil, and it was this sub-10-μm fraction that was found to hold most of the total nickel present in the soil. The
fine fraction was analyzed using a simulated lung fluid (modified Gamble’s solution) to isolate the nickel phases soluble
in the lungs. In addition, a sequential extraction was employed to compare the bioaccessible fraction to those dissolved from
different binding forms in the soil. In all samples, the simulated lung fluid extracted more nickel than the two weakest leaches
of the sequential extraction combined, providing a more representative nickel bioaccessibility value than the current water
leach method. 相似文献
14.
The mobility of aluminium in sediments was evaluated through a one-step extraction with a strong chelating agent. Single and
sequential extraction procedures for the extraction of Al were applied to four sediments from a polluted region. A single-step
extraction with 0.05 mol L−1 ethylenediaminetetraacetic acid (EDTA) was used, and compared with a standardized SEP as reference. The Al contents extracted
into Na2EDTA were in good agreement with the sequential extraction that yeilds mobile and potentially mobile portion of Al. Extracted
EDTA contents make up more than 70% of the first-three-step sum of the five-step extraction procedure. Thus, Na2EDTA extraction of Al could be applied to assess aluminium mobility changes in sediments and soils. 相似文献
15.
土壤中锰氧化物的形态及其化学提取方法综述 总被引:1,自引:0,他引:1
土壤中锰元素主要来自于成土母质,风化后的锰主要以锰氧化物形式存在于土壤中.锰氧化物因具有比表面积大、表面电荷低、对金属的亲合力强、氧化还原电位高等特性,对土壤中痕量金属的环境行为存在重要影响.化学提取方法是研究土壤中不同固相组分的重要手段.本文首先从土壤中锰的来源及主要存在形态出发,介绍了不同价态锰(+2、+3、+4)... 相似文献
16.
17.
本文采用化学逐级提取法对吸附锌后的土壤分别提取了交换态、CaCO_3结合态、氧化物结合态和有机质结合态的锌量,并讨论pH、温度和溶液中锌离子浓度对不同形态锌分布的影响。实验结果表明:外加锌被石灰性土壤吸附后,高pH值(7.5)时形态分布为:CaCO_3结合态≥交换态>氧化物结合态>有机质结合态;低pH值(5.5)时则为:交换态>CaCO_3结合态>氧化物结合态>有机质结合态。各形态锌的分配系数还受到吸附时的温度和溶液中锌离子浓度的影响。 相似文献
18.
《Chemistry and Ecology》2008,24(2):147-156
The main objective of this study was to investigate the efficiency of different substrates to reduce the extraction of heavy metals concentration in a heavily contaminated soil. Two contaminated soils by Cu and Zn were used to evaluate the effectiveness of eight substrates (calcium carbonate, bentonite, kaolinite, charcoal, manganese oxide, iron oxide, zeolite, phosphate) to reduce metal availability and to study the change of metals speciation in different forms using sequential extraction technique (single step). Sequential extraction technique (single step, 0.11 M acetic acid, HONH3Cl, H2O2+NH4OAc, Aqua regia) was applied on contaminated soils after and before treatment to evaluate metals speciation. Results indicate that the most effective treatments in decreasing available metal concentrations were calcium carbonate, zeolite and manganese or iron oxide. Metal sequential fractionations indicate that the exchangeable fraction of Cu and Zn in contaminated soils can be transformed into unavailable forms after chemical remediation. 相似文献
19.
Modelling the concentrations of dissolved contaminants (Cd,Cu, Ni,Pb, Zn) in floodplain soils 总被引:1,自引:0,他引:1
Central European floodplain soils are often contaminated with potentially toxic metals. The prediction of their aqueous concentrations is a prerequisite for an assessment of environmental concerns. We tested the aqueous concentrations of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) derived from multi-surface adsorption modelling (on hydrous iron, aluminum and manganese oxides, clay and soil organic matter) against those analyzed in situ in the soil solution of four horizons of floodplain soils at the Elbe River, Germany. The input data for the reactive metals were derived from a seven-step sequential extraction scheme or from extraction with 0.43 M nitric acid (HNO3) and evaluated in four modelling scenarios. In all scenarios, measured and modelled concentrations were positively related, except partially for Pb. Close reproduction of the measured data was obtained using measured data of accompanying cations and anions together with amounts of reactive metals from both the sequential extraction or from 0.43 M HNO3 extraction, except for Cu, which was often strongly overestimated, and partially Cd. We recommend extraction with 0.43 M HNO3 to quantify reactive metals in soil because the modelling results were metal-specific with better or equal results using the single extractant, the application of which is also less laborious. Approximations of ion concentrations and water contents yielded similar results. Modelled solid-phase speciation of metals varied with pH and differed from that from sequential extraction. Multi-surface modelling may be an effective tool to predict both aqueous concentrations and solid-phase speciation of metals in soil. 相似文献