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1.
外源铜和镍在土壤中的化学形态及其老化研究   总被引：2，自引：0，他引：2  
采用连续提取法测定了外源铜和镍进入田间土壤后的化学形态分布,比较研究了这2种重金属在3种不同类型土壤(红壤,水稻土和潮土)中随老化时间的形态转化和分布.结果表明,外源铜以残留态(40%～60%)和EDTA可提取态(40%)为主;随老化时间,EDTA可提取态、易还原锰结合态及铁铝氧化态向残留态转化;外源镍在酸性红壤中以可交换态(40%)和残留态(30%～50%)为主,在中性水稻土中以EDTA可提取态(30%)和残留态(30%～50%)为主,在碱性潮土中以铁铝氧化态(20%)和残留态(40%)为主.随老化时间,水溶态、可交换态、EDTA可提取态等向残留态转化.土壤pH较低时水溶态和可交换态含量较高,但是同时随老化时间的降低量也明显;pH较高时有利于易还原锰结合态和有机质结合态的转化.  相似文献   

2.
Heavy metals can be transferred from soils to other ecosystem parts and affect ecosystems and human health through the food chain. Today the use of biosolids to improve the nutrient contents of a soil is a common practice. Contamination of soils by potentially toxic elements (e.g., Cd, Ni, Cr, Pb) from amendments of biosolids is subject to strict controls within the European Community in relation to total permissible metal concentrations, soil properties and intended use. In this context, heavy metal concentrations were studied in agricultural soils devoted to vegetable crops in the province of Alicante (SE Spain), where an intensive agriculture takes place. This study is aimed at ascertaining the chemical partitioning of Cd, Ni, Cr, and Pb in agricultural soils repeatedly amended with sludge. Selected soil properties relevant to control the mobility and bioavaibility of heavy metals were analyzed for the general characterisation of these agricultural soils. The distribution of chemical forms of Cd, Ni, Cr, and Pb in five biosolids-amended soils was studied using a sequential extraction procedure that fractionates the metal into soluble-exchangeable, specifically sorbed-carbonate bound, oxidizable, reducible, and residual forms. The biosolids incorporation has modified the soil composition, leading to the increment of heavy metals. The residual, reducible, and carbonate-sorbed forms were dominant. Detailed knowledge of the soil at the application site, especially pH, CEC, buffering capacity, organic matter, clay minerals, and clay content, is essential.  相似文献   

3.
长期定位施肥对土壤铁、锰形态及剖面分布的影响   总被引：3，自引：0，他引：3  
本文采用改进的BCR连续提取法,对沈阳农业大学棕壤肥料长期定位试验地31年不同施肥处理土壤铁和锰含量变化及其剖面变异规律进行研究。结果表明:与试验前相比,耕层土壤两种元素水溶态和弱酸溶态含量都有所增加,而可还原态和残渣态含量则有不同程度的减少;铁和锰都以残渣态和可还原态为主。在空间分布上,两种元素弱酸溶态和可氧化态含量随土层的加深而减少,残渣态则相反。研究表明,有机肥能在一定程度上改变铁和锰在各形态间的分配,并且有机肥能活化残渣态铁和锰。  相似文献   

4.
Abstract

Soil samples from a field irrigated with untreated industrial and municipal wastewater for several decades and from a field not receiving wastewater (control) were analyzed for total copper (Cu) and zinc (Zn) and for the amount of these elements removed in sequential extractions with MgCl2, NaOAc, NH2OH#lbHCl, 6H2O2‐HNO3‐NH4OAc, and HNO3‐HF‐HCl. Organically‐bound Cu forms predominated in the wastewater‐affected soil while in the control soil both residual and organic forms yielded the same proportion of Cu. Distribution of Zn was different in the diverse fractions, and in the polluted soil the reducible and the residual forms predominated while in the control soil the residual form accounted for the highest proportion of recovered Zn. Sequential extraction of Cu from a copper sulfate‐treated soil incubated for 32 days at constant temperature resulted in the same proportional distribution of Cu forms in the polluted soil. In the control soil the oxidizable form decreased and the residual one increased noticeably. The two‐surface Langmuir adsorption model was used to adjust data and to interpret Cu and Zn adsorption by soils excepting Cu sorption by the polluted soil, where the one‐surface model was applied.  相似文献   

5.
施污土壤与污泥中Cu、Pb、Cd、Zn的形态分布   总被引：2，自引：0，他引：2  
污泥中的重金属元素是限制其大规模农田利用的重要因素。施污土壤和污泥中重金属的形态研究可以用来评价土壤中重金属的生物有效性以及它们在土壤中的移动性。用修正BCR三步连续提取法进行分步提取研究了污水污泥和施污后的西红柿地土壤中Cu、Pb、Cd、Zn的形态分布状况。施用污泥堆肥10t hm-2后的土壤中Cu、Pb、Cd、Zn的全量与各种形态含量无明显增加,Cu、Pb、Zn含量远低于国家土壤环境质量标准。土壤中Cu的各种形态分布关系是:残渣态>可还原态=可氧化态>可交换态和弱酸溶解态,Cu在土壤中的存在是以最稳定的残渣态为主。堆肥污泥与干化污泥相比,残渣态Cu的比例明显增加。土壤中Pb的各种形态分布关系是以残渣态和可还原态为主,但可氧化态的分布比例最小。土壤中Cd的可交换态、可还原态和残渣态各占据相等的含量,但可氧化态Cd的含量几乎为零。Zn在土壤中的各种形态分布关系是:可交换态和弱酸溶解态>可氧化态>可还原态>残渣态,Zn在土壤中的存在是以最易迁移的可交换态和弱酸溶解态为主。这些金属元素在土壤中的相对稳定性顺序为:Cu>Pb>Cd>Zn。Zn在土壤中的移动性要远高于Cu。  相似文献   

6.
Abstract

A previous study indicated that agricultural biosolid applications increased the concentration of EPA3050‐digestible trace elements in soils on Pennsylvania production farms but could not indicate potential trace‐element environmental availability. This study was conducted to determine if biosolid application had altered the distribution of trace‐elements among operationally defined soil fractions and the relationship of trace element concentrations in soil and crop tissues. Biosolid‐amended and unamended soils from production farms in Pennsylvania were extracted using a modified Bureau Communautaire de Référence (BCR) sequential fractionation technique and analyzed for chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Trace‐element concentrations in crop tissues (soybean silage, sudangrass, corn grain, alfalfa hay, and orchardgrass hay) from the same farms were also determined. Fractionation results indicated that the proportion of Cr, Cu, Ni, Pb, and Zn that is potentially bioavailable is quite small in unamended soils. Biosolid applications significantly (P≤0.1) increased concentrations of Cu in all soil fractions (average increase over unamended soil=1.14, 8.27, 6.04, and 5.84 mg kg?1 for the exchangeable, reducible, oxidizable, and residual fractions, respectively), Ni (0.41, 1.65 mg kg?1 for the reducible and residual fractions, respectively), Pb (5.12 and 1.49 mg kg?1 for the reducible and residual fractions, respectively), and Zn (8.28, 7.12, 4.44, and 8.98 mg kg?1 for the exchangeable, reducible, oxidizable, and residual fractions, respectively) but did not significantly increase Cr in any soil fraction. Concentrations of Cu in all soil fractions were significantly (P≤0.01) correlated with concentrations of Cu in orchardgrass tissue (r=0.70, 0.66, 0.76, and 0.69 for the exchangeable, reducible, oxidizable, and residual soil fractions, respectively). Concentrations of exchangeable and reducible Zn were significantly correlated with Zn in sudangrass tissue (r=0.81 and 0.67), and reducible Zn was significantly correlated with Zn concentrations in orchardgrass tissue (r=0.65). Application of biosolids had little effect on bioavailability of Cr, Ni, or Pb, whereas higher loadings of Cu and Zn led to a shift toward the more labile soil fractions. Loadings of Cu and Zn were much smaller than cumulative loadings permitted under U.S. Environmental Protection Agency (USEPA) Part 503 regulations. Chemical soil fractionation was able to detect increases in labile soil Cu and Zn that relate to increased phytoavailability.  相似文献   

7.
酸化及施碳酸钙对土壤各形态锰的影响   总被引：7，自引：1，他引：7  
以灰潮土为对照 ,研究了华中地区 3种已明显发生酸化的土壤在施用碳酸钙前后各形态锰的变化情况。结果表明 ,已酸化的红壤、棕红壤和黄褐土施用碳酸钙降低了土壤酸度 ,土壤交换态锰随 pH值上升而降低 ,其降幅分别为 42 % ,49%和 39% ;其它形态锰的增减随各土而异 ,残留态锰较稳定 ,变幅小。作为对照 ,灰潮土虽与前 3种已酸化土壤一样种植过多茬作物 ,但其交换态锰含量仍甚微。无论是否施用碳酸钙 ,在灰潮土的交换态锰、碳酸钙结合态锰和易还原态锰 3种形态锰中 ,易还原态锰占 80 %以上 ,说明易还原态锰是其活性锰的主要部分  相似文献   

8.
采用改进BCR法和DTPA提取法研究了韶关主要矿区周边农田土壤Pb、Cd的形态分布和生物有效性。结果表明,参照土壤环境质量标准二级标准,韶关主要矿区周边农田土壤Pb、Cd的超标率分别为14.1%和92.3%;参照食品中污染物限量标准,调查的5种蔬菜样品Pb、Cd的超标率分别为57.7%和48.7%。土壤Pb以可还原态为主,占到4种形态和的76.13%,Pb各形态的分布顺序为：可还原态〉残渣态〉可氧化态〉酸提取态;土壤Cd以酸提取态和可还原态为主,占到4种形态和近89%,Cd各形态的分布顺序为：酸提取态〉可还原态〉可氧化态〉残渣态。用DTPA提取得到的土壤Pb、Cd有效态均值分别为24.91、1.29 mg·kg-1。相关性分析表明,除了胡萝卜Cd,5种蔬菜Pb、Cd含量与土壤酸提取态、可还原态、可氧化态及土壤有效态含量显著相关,与土壤pH和有机质相关性不大。逐步回归分析表明,只有土壤残渣态含量对蔬菜Pb、Cd含量影响不显著。  相似文献   

9.

Purpose

With widely applied water-saving irrigation techniques, the transformation and availabilities of copper (Cu) as both a micronutrient and a toxic metal are changed. However, little information is available on the binding forms, bioavailability, and fate of Cu in paddy fields with different irrigation management. Thus, we investigated the effects of irrigation management on the binding forms and the fate of Cu in a non-polluted paddy soil.

Materials and methods

Field experiments were conducted in 2011 on non-polluted rice fields in Kunshan, East China. Non-flooding controlled irrigation (NFI) was applied in three replications, with flooding irrigation as a control. Samples of soil, soil solution, irrigation water, and rice plants were collected. Fresh soil samples were digested using the modified European Community Bureau of Reference sequential extraction procedure and the dried crop samples digested at 160 °C using concentrated HNO3. Cu contents in irrigation water, soil solution, extraction for different binding fractions, and the digested solutions were measured using inductively coupled plasma optical emission spectrometry. Leaching loss of Cu was calculated based on the Cu contents in 47- to 54-cm soil solutions and deep percolation rates, which were calculated using the field water balance principle.

Results and discussion

NFI led to multiple dry–wet cycles and high soil redox potential in surface soil. The dry–wet cycles in NFI soil resulted in higher Cu contents in acid-extractable and oxidizable forms and lower Cu in residual form. High decomposition and mineralization rates of soil organic matter caused by the dry–wet cycles partially accounted for the increased Cu in acid-extractable form in NFI soils. The frequently high contents of Cu in reducible form in NFI fields might be due to the enhanced transformation of Fe and Mn oxides. As a result, Cu uptakes in NFI fields increased by 8.1 %. Meanwhile, Cu inputs by irrigation and loss by leaching in NFI fields were reduced by 47.6 and 46.6 %.

Conclusions

NFI enhanced the transformation of Cu from residual to oxidizable and acid-extractable forms. The oxidizable form plays a more important role than the reducible form in determining the transformation of Cu from the immobile to the mobile forms in NFI soils. NFI helps improve availability and decreases leaching loss of Cu as a micronutrient in a non-polluted paddy soil, but leads to a high concentration of Cu in rice.  相似文献   

10.
基于类型土壤的重金属元素形态分析研究相对较少,本研究以香港地区7个亚纲的土壤剖面为例,利用欧共体参比司(BCR)制定的三步连续提取法研究了类型土壤中重金属Cd、Cu、Pb和Zn的化学形态及其潜在环境风险。结果表明,Pb、Cd和Zn元素除残留态外,HOAc溶解态的比例也相对较高,但不同类型的土壤有所差别,而Cu元素则以残留态和可氧化态为主。在这7种类型土壤中,正常潜育土和湿润淋溶土中的重金属潜在环境风险相对较高,而在这4种重金属元素中,又以Pb元素的潜在环境风险最大。  相似文献   

11.
针对质地黏重、低渗透性黏性土的淋洗效率低下,该文提出冻融协同化学淋洗的修复方案,并以某冶炼厂受Cd、Pb污染场地黏性土为研究对象,选用乙二胺四乙酸二钠(ethylene diaminetetraacetic acid disodium salt,EDTA)为淋洗剂,进行了冻融-淋洗土柱的实证试验。结果表明,土体的反复冻融(冻胀-吸水、融沉-排水)破坏土体颗粒原有结构,有助于淋洗液与污染物充分接触,淋洗效果明显,经7次冻融后,Cd、Pb去除率分别达到77.24%、37.78%。采用改进的BCR(European Communities Bureau of Reference)连续提取法分析了土柱中Cd、Pb的赋存特征,经7次冻融后,土壤中弱酸提取态、可还原态、残渣态结合的Cd质量分数较淋洗前分别降低了41.46%、63.02%、26.33%,而土壤中可还原态和残渣态结合的Pb质量分数分别降低了32.32%、67.36%。冻融协同化学淋洗修复技术的淋洗剂用量远小于传统淋洗法,为今后利用寒区冻融交替现象,大规模对季冻区重金属污染土壤的异位修复提供了新的思路。  相似文献   

12.
为了筛选出能有效抑制水稻各部位吸收积累Cr和Cu的有机和无机材料钝化剂组合,选取水稻土以盆栽试验研究了15种钝化剂组合对土壤Cr和Cu赋存形态及水稻各部位吸收积累Cr和Cu的影响。结果表明:15种钝化剂组合施用使土壤pH上升0.25～1.04,土壤阳离子交换量增加2.65%～50.96%,土壤有机质含量增加0.22%～17.20%,土壤可交换态Cr含量降低35.21%～55.63%;除生石灰+钝化剂4+鸡粪组合使土壤可还原态显著增加外,其他组合的土壤可还原态Cr无显著变化;土壤可氧化态和残渣态Cr均无明显变化;土壤可交换态Cu含量降低6.66%～33.42%;土壤可还原态和可氧化态Cu无明显变化;土壤残渣态Cu增加0.32%～5.04%,其中钝化剂3、生石灰+钝化剂1+鸡粪、生石灰+钝化剂4+鸡粪3个组合能显著增加土壤残渣态含量。根系对Cr和Cu的富集能力最大,15种钝化剂组合可使水稻根系、秸秆、稻壳和糙米中Cr含量分别下降4.59%～49.41%,39.84%～76.87%,7.14%～31.60%,17.32%～67.10%,水稻根系、秸秆、稻壳和糙米中Cu含量分别下降10.57%～48.41%,7.99%～52.53%,21.12%～45.11%,14.39%～66.92%。15种钝化剂组合均可降低糙米中Cr和Cu的含量,其中以生石灰+钝化剂2+鸡粪的效果最佳。  相似文献   

13.
An experiment was conducted to evaluate the effect of zinc (Zn) rates and vermicompost levels on distribution of Zn forms of a calcareous soil. After incubation periods, soil samples were air dried, and a sequential extraction scheme was used to fractionate Zn into soluble and exchangeable, bound to carbonate, organically bound, bound to manganese (Mn) oxide, bound to amorphous iron (Fe) oxide, bound to crystalline Fe oxide, and residual forms. In untreated soil, Zn was mainly in the residual fraction. Increasing rates of applied Zn significantly increased all forms of Zn. Carbonate and residual forms showed the greatest increase. Application of vermicompost significantly increased all fractions except Mn-oxide form. This increase was more pronounced for organically bound, soluble, and exchangeable forms, indicating an increase in bioavailability of soil Zn. Incubation time significantly decreased soluble, exchangeable, and organically bound forms but increased other forms of Zn, meaning a significant reduction in Zn phytoavailability in soil with time.  相似文献   

14.
Co,Ni,Cr and V in 25 typical soils of China were fractionated into exchangeable,carbonate bound (calcareous soils),Mn oxide bound,organically bound,amorphous Fe oxide bound,crystalline Fe oxide bound and residual forms using a seven-step sequential extraction procedure,so as to study the distribution of chemical forms of these metals as well as the effects of soil proiperties on the distribution.The results showed that most of soil Co,Ni,Cr and V were present in residual forms,and the distribution ratio averaged 48.2% for Co,53.0% for Ni,81.5% for Cr and 68.7% for V.The speciation of heavy metals was greatly influenced by soil physico-chemical properties and the chemistry of elements.The results also indicated that the recovery of metal elements by the sequential extraction procedure was satisfactory,with the relative difference between the sum of seven forms and the total content in soils averaging 9.5% for Co,12.8% for Ni,6.6% for Cr and 7.2% for V.  相似文献   

15.
板栗土壤中微量营养元素地球化学特征   总被引：1，自引：0，他引：1  
同时采用有效态和欧共体BCR(the Community Bureau of Reference)三步提取法对0-20 cm和20-40 cm土层中Ca,Mg,Fe,Zn,Cu,Mn进行形态分析,探索燕山山区板栗土壤中微量营养元索活性、形态分布特征和迁移能力.结果表明.栗粮间作会影响板栗对营养元素的吸收,且两层土壤中各元素活性相差不大;板栗纯林中0-20 cm土层的Cu,Zn活性明显高于20-40 cm土层;淋溶褐土和褐土性土两种土壤亚类,不同栽培制度对微量营养元素在板栗土壤中的形态分布特征影响不大.Cu,Zn,Fe主要以残渣态存在,Mn主要以可还原态和残渣态存在.且弱酸提取态高于其它元素.板栗土壤中元素的迁移能力排序为:Ca>Mg>Mn>Cu>Zn>Fe.  相似文献   

16.
Classical chemical fractionation of soil sulphur (S) into HI‐reducible S and carbon‐bonded S does not separate S in soil into fractions that have differing mineralization potentials. Other techniques are needed to separate organic S into more labile and less labile fractions of biological significance, irrespective of their bonding relations. We have sequentially fractionated soil S and carbon (C) into their ionic forms released onto ion‐exchange resins and organic S and C extracted in alkali of increasing concentration. We evaluated the technique on pasture and arable soils that had received various fertilizer and cultivation treatments. Total S and C were greater in the soil of the fertilized pasture than in that of the unfertilized pastures. Continuous arable cropping decreased total soil S and C, whereas restoration to pasture caused an accumulation. Resin, 0.1 m NaOH, 1 m NaOH and residual fractions accounted for between 1–13%, 49–69%, 4–16% and 19–38% of total soil S and between 5–6%, 38–48%, 5–7% and 46–53% of total soil C, respectively. Among different S and C fractions, the size of the 0.1 m NaOH and residual fractions changed more with the change in land use and management. The 0.1 m NaOH fraction had a narrower C:S ratio (50–75:1) than did the residual fraction (96–141:1). The significant degree of change in these two fractions, caused by differences in land management, indicates that they may be useful indicators of change in ‘soil quality’.  相似文献   

17.
B. TODOROV  R. DJINGOVA 《土壤圈》2015,25(2):212-219
Monitoring the behavior of radioactive contaminants associated with military applications,nuclear power facilities,and interim storage of radioactive waste materials is of significant concern in radiological analysis.Four sequential extraction schemes（SES） for fractionation of 241Am were compared using five different types of soils,Vertisol,Cambisol,Chromic Luvisol,Eutric Fluvisol,and mixed urban soil,collected from different parts of Bulgaria.The results for the exchangeable 241 Am were in a wide range and depended on the SES used.Soil 241Am varied from 0.5%to 6%in the exchangeable phase,from 0.5%to 35%in the carbonate phase,from0.4%to 36%in the reducible phase（easily reducible and moderately reducible）,from 3%to 17%in the oxidizable phase,and from10%to 50%in the residual phase.After 100 d of contamination,around 50%of soil 241Am was permanently fixed in the residual phase.There was strong evidence that the preferable soil phase for 241 Am was the carbonate phase.The transfer factor of 241 Am in the soil-plant system depended on 241Am in the easily oxidizable phase（fulvic acid（FA）+humic acid（HA） phase）.These confirmed the applicability of the National Institute of Standards and Technology（NIST） sequential extraction scheme for fractionation of soil241 Am since it includes extraction of FA+HA phase and then the carbonate phase.  相似文献   

18.

Purpose

The purpose of this study was (1) to determine the vertical distribution of rare earth element (REE) concentrations, stocks, and geochemical fractions in two different marsh soil profiles and (2) to quantify the relations between REEs and soil properties.

Materials and methods

A sandy Fluvisol recently flooded by tidal water and a clayey Gleysol landward the dike impacted by fluctuating groundwater levels served as reference marsh soils. An aqua regia extraction was used to determine the concentrations of REEs; additionally, a sequential extraction procedure developed by the Commission of the European Communities Bureau of Reference was conducted to assess the geochemical fractions (exchangeable, reducible, oxidisable, residual fraction) of REEs. Both extractions were carried out according to genetic horizons. The stocks of REEs were calculated and the relations between physico-chemical soil properties and concentrations/mobility of REEs were quantified via correlation analysis.

Results and discussion

The aqua regia extractable REE concentrations and stocks of the Gleysol were about two times higher compared to the Fluvisol since the Gleysol was more clayey and REEs might adsorb onto clay minerals. We have detected small differences of REE concentrations and geochemical fractions between the horizons of the single profiles. Rare earth elements existed mainly in residual or reducible fraction, followed by oxidisable, and water soluble/exchangeable/carbonate bound fraction. The most striking difference between the two marsh soil profiles regarding the geochemical fractions was the higher residual fraction in the Fluvisol than in the Gleysol what seemed to be due to the lower aqua regia extractable concentration in the former.

Conclusions

The aqua regia extractable concentration as well as reduction and oxidation processes of (amorphous) iron and manganese complexes seemed to have the most important impact on the geochemical fractions of REEs in the studied marsh soil profiles. In future, those findings should be verified in further marsh soils worldwide. In particular, future studies should elucidate the specific release kinetics of REEs and their determining factors.  相似文献   

19.
Traditionally, the Guadiamar River (Seville, Southwest Spain) has received pollution from two different sources, in its upper section, from a pyrite exploitation (Los Frailes mine) and, in its lower section, from untreated urban and industrial wastes and from intensive agricultural activities. In 1998, the accidental spillage of about 6 million m3 of acid water and sludge from mine tailings to Guadiamar River worsened the pollution of an already contaminated area. The main polluting agents of the spillage were heavy metals. The total concentration of a metal provides scarce information about the effects on environmental processes or about the toxicity of the sediment samples. A more sophisticated fractionation of the sediment samples based on a species distribution can help to understand the behaviour and fate of the metals. This article describes a distribution study of the metals Al, Cd, Cu, Fe, Mn, Pb and Zn by fractionation analysis of sediments from eleven sample sites alongside the Guadiamar Riverbed. The samples were collected in summer 2002, four years after the spillage and after the area had been cleaned. Sequential extraction analysis resulted in the definition of four fraction categories: exchangeable metal (the most available fraction), reducible metal (bound to hydrous oxides of Fe and Mn), oxidizable metal (bound to organic matter and sulphides) and a residual fraction (bound to minerals). Significant increases in the available fraction of several potentially toxic metal ions like Cd, Mn and Zn were found. The distribution pattern was variable along the River. At the site closest to the mineworks, the soluble forms of Cd, Mn and Zn were significantly more abundant that those downstream. Cu and Pb were present in the reducible fraction while Fe was present associated in the residual fraction.  相似文献   

20.
Effective remediation and sanitation technologies for soils contaminated with heavy metals are limited. We investigated the feasibility of a counter-current metal extraction procedure for the removal of selected heavy metals (Cd, Cu, Ph, and Zn) from two contaminated soils. The process involved a decarbonation (removal of carbonates), acid solubilisation, washing, and liming step. Results from batch equilibration experiments simulating the counter-current process showed more than 85% of the Cd present to be removed. Removal efficiencies for Cu and Pb were limited to approximately 15%, this mainly due to resorption of these elements during the decarbonation step. As most Zn was found to be present in a more difficult acid-extractable solid phase, its extractability accounted for only 25%. While reaction (pH) conditions of both decarbonation and solubilisation determined removal efficiencies, washing the extracted soil with deionized water only slightly increased the amount of metals removed. Metal distribution among solid phases — exchangeable, carbonate, reducible, organically bound, and residual — was affected by the different treatments. The amount of metals contained in the exchangeable and residual fractions determined their extractability. Except for Cu, the reducible and organically bound fractions were less important. After solubilisation 13 to 70% of the metals were present in an exchangeable solid phase. This implicates that washing the solubilized soil with a salt may increase the extractability of metals, especially for Zn and Pb. Based on our results the process is critically evaluated and possibilities for optimization formulated.  相似文献   

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