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1.
Yu. N. Vodyanitskii 《Eurasian Soil Science》2013,46(3):317-324
The surface horizons of urban soils are enriched in technogenic magnetite Fe3O4 accumulated from emissions. Its content there reaches 3–4% and more, whereas it does not exceed 0.1% in the back-ground soils. In urban soils, large spherical magnetite particles of pseudo-single-domain and multidomain fabric predominate; the cavities in magnetic spherules decrease their chemical stability and increase their reactivity. Magnetite is most often destroyed in urban soils due to complexing; its destruction may be initiated by mineral salts entering the soil with deicing mixtures and by organic acids excreted by roots (e.g., by oxalic acid). The high solubility of magnetite with ammonium oxalate should be taken into account when using Tamm’s reagent for the analysis of urban soils. Magnetite is a mineral carrier of some heavy metals. Therefore, its content (as determined from the magnetic susceptibility) serves as an indirect index of soil pollution. In addition, magnetite may affect many soil properties as a reducer and sorbent. It adsorbs phosphorus thus preventing the penetration of this nutrient into rivers and lakes. Magnetite also oxidizes Cl-containing aliphatic hydrocarbons and purifies the soil. Although magnetite enters urban soils as a pollutant, its influence on the soil properties cannot be unambiguously judged as only negative. 相似文献
2.
Yu. N. Vodyanitskii 《Eurasian Soil Science》2010,43(3):269-277
Zinc has no particular bearing phases in soils, and it forms very diverse compounds; this complicates zinc’s identification
by chemical fractionation. However, Zn-containing particles may be identified using synchrotron X-ray analysis. Franklinite,
willemite, hemimorphite, and Zn-containing magnetite are found to be the main technogenic Zn-containing pollutants in the
heavy fraction of the contaminated surface soil horizon. Among the secondary zinc compounds, Zn-containing trioctahedral structures
and clay minerals (unidentifiable by chemical extraction), as well as zinc fixed by manganese oxides and iron hydroxides,
predominate in the soil clay fraction. Being a chalcophile element, zinc precipitates in the form of sulfides and forms complexes
with organic substances in organic soils and peats. The degree of affinity to chalcophile metals increases in the following
sequence: O-, P-, N-, and S-containing functional groups of organic substances. 相似文献
3.
Tatiana M. Minkina Vitaly G. Linnik Dina G. Nevidomskaya Tatiana V. Bauer Saglara S. Mandzhieva Vitaliy Y. Khoroshavin 《Journal of Soils and Sediments》2018,18(6):2217-2228
Purpose
The aim was to study Cu (II), Zn (II), and Pb (II) forms in technogenically transformed soils adjacent to the Karabashmed copper smelter.Materials and methods
Studies were performed in the plume zone of the Karabash smelter and in the floodplains of Ryzhii Brook and Sak-Egla River. Geomorphological and geochemical migration processes prevail in technogenic landscapes. The differentiation of landscape-geochemical conditions plays the dominant role, which determines the localization of metals. The total Mn, Cr, Ni, Cu, Zn, Pb, Cd, and As contents and the macroelement compositions of soils were determined by X-ray fluorescence. The composition of Cu, Pb, and Zn compounds in soils was determined by the Tessier sequential fractionation. The determination of the geochemical fractions of heavy metals in soils is a key issue in the study of their mobility. The metals were fractionated into the following five fractions: exchangeable, bound to carbonates, bound to Fe and Mn oxides, bound to organic matter, and residual fractions.Results and discussion
It is shown that the total Zn and As contents in the 0- to 5-cm layer of soils on monitoring plots exceed their lithosphere clarks in hundreds of times, and the total Cu, Pb, and Cr contents exceed their lithosphere clarks in tens of times. Factors and processes controlling the distribution and transport of Cu, Pb, and Zn forms in soils were determined. According to landscape-geochemical differentiation, the eluvial (automorphic) catena (plot T4) takes the main technogenic load of dust fallouts from the Karabash copper smelter. The accumulation of material brought from above and the geochemical precipitation of discharges from tailings dumps occur in superaqual catenas (plots T1, T2, and T3). In the technogenically transformed soils, the basic stabilizers of the mobility of Cu is organic matter, for Pb it is Fe-Mn (hydro) oxides, and for Zn - it is clay minerals.Conclusions
The distributions of Cu, Zn, and Pb forms in the studied technogenically transformed soils are due to a number of factors: First, these are the composition of technogenic pollutants contaminating ecosystems and the time during which the contamination occurred, and second, this is the combination of physicochemical properties controlling the buffer properties of the polydisperse system of soils and parent materials.4.
Yu. N. Vodyanitskii 《Eurasian Soil Science》2013,46(6):635-643
Technogenic magnetite in urban soils is extremely various in properties. Its particles strongly differ in magnetic susceptibility and degree of association with heavy metals. In the city of Perm, particles of magnetite enriched with different heavy metals are precipitated, which indicates different sources of technogenic magnetite within the limits of the city. The dissolution of magnetite and the effect of this process on the behavior of heavy metals have been simulated by the magnetochemical method. In strongly magnetic soils, the dissolution of highly magnetic macrocrystalline magnetite is accompanied by the dissolution of heavy metals: Cr, Mn, Ni, Zn, Pb, and Cu. The secondary precipitates of hydroxides of iron and heavy metals (predominantly Pb, Cu, and Ni) are formed relatively rarely, mainly in weakly magnetic soils, where slightly magnetic and dispersed magnetite is present. In cities, the dissolution of magnetite is favored by the added salts and organic acids released by plants. 相似文献
5.
Yu. N. Vodyanitskii A. T. Savichev A. A. Vasil’ev E. S. Lobanova A. N. Chashchin E. V. Prokopovich 《Eurasian Soil Science》2010,43(7):822-832
The contents of heavy alkaline-earth (Sr and Ba) and rare-earth (Y, La, and Ce) metals have been studied in two technogeochemical
anomalies and in the soils of Perm and Chusovoi. The soils are contaminated with barium, lanthanum, and cerium in the territory
of the Cherepovets technogeochemical anomaly formed due to the atmospheric emissions from the Severstal metallurgical works.
Strontium, barium, and yttrium are accumulated in the soils of the Revda technogeochemical anomaly formed by aerial emissions
from the Mid-Urals copper smelter. The portion of technogenic strontium reaches 43–84% near the metallurgical works, while
that of barium and yttrium, 47–63 and 28–32%, respectively. In Perm, the urban soils are polluted with technogenic alkaline-earth
metals, i.e., strontium and barium, with their content reaching 31–48%. In Chusovoi, the calcareous horizons of the soddy
soils are enriched in strontium and depleted in barium. The eluvial-illuvial distribution of the rare-earth metals is registered
in the soddy-podzolic soil. The soils of the terrace are contaminated with barium. The technozem is contaminated with all
the metals (barium and yttrium, in particular). 相似文献
6.
Criteria of the technogenic nature of heavy metals and metalloids in soils: A review of publications
Yu. N. Vodyanitskii 《Eurasian Soil Science》2009,42(9):1053-1061
Both routine statistical methods (the compliance of the heavy metal content with the exponent or ruling out abnormally high
values of heavy metal concentrations in the Gaussian distribution) and new geostatistics based approaches are used as the
criteria of the technogenic nature of heavy metals. Methods are being developed that take into consideration the marker element
content (Al) in soil profiles. The geochemical criteria of the technogenic character are based on the statistical relationship
between the content of the particular heavy metal (or metalloid) and its principal mineral phase carrier in the background
soils, as well as on the disturbance of this relationship upon soil pollution. The chemical criteria are based on the different
solubility of natural and technogenic heavy metals by reagents. A procedure of the quantitative assessment of the origin of
technogenic lead depending on its isotopic composition is developed. The magnetic criteria of the technogenic nature of heavy
metals are based on their association with technogenic magnetite. 相似文献
7.
Natural and technogenic compounds of heavy metals in soils 总被引：1，自引：0，他引：1
Yu. N. Vodyanitskii 《Eurasian Soil Science》2014,47(4):255-265
The existing geological classification of heavy metals (HMs) is not suitable for their characterization in soils. The carriers of HMs in soils differ from those in the lithosphere. These are clay minerals; iron oxides, whose composition varies between the background and urban soils; various manganese oxides; and different groups of organic substances. The mineral composition of HM carriers can vary significantly. The main iron oxides are ferrihydrite, goethite, feroxyhyte, and lepidocrocite in the background soils and technogenic magnetite in the urban soils. The different structures of manganese oxides determine their affinity for specific HMs. Metallic iron and green rust are very efficient in artificial geochemical barriers, although they act as strong reducers there. HM compounds strongly vary in soils because of the unstable conditions. 相似文献
8.
E. V. Tishkina T. A. Paramonova S. F. Krasnov D. O. Tolstikhin 《Moscow University Soil Science Bulletin》2010,65(1):39-45
Soils of the Vorob’evy Gory nature park (Moscow) are characterized by a high content of technogenic ecotoxicants. Dangerous
levels of pollution are fixed on ∼60% of soil cover for benzopyrene, ∼40% of soil cover for heavy metals, and ∼6% of soil
cover for mineral oils. Besides the total high aerogenic load, the local sources of soil pollution in cities are highways;
increased concentrations of heavy metals are also registered near unauthorized dumps. Benzopyrene and mineral oils are characterized
by high migratory ability in soils and can form secondary auras of pollution in accumulative landscape facies. 相似文献
9.
The dependence of the level of contamination of the upper horizon of Al–Fe-humus podzols (Podzols Rustic) with heavy metals (Ni, Cu) on the distance from the Severonickel smelter (Monchegorsk, Murmansk oblast) was studied on a number of test plots in the medium-aged pine stands. It was found that metal concentrations in the soils could be reasonably approximated by the negative exponential function. In the buffer zone of the smelter, the concentrations of Ni and Cu exceed background values by 8–17 times; in the impact zone, by 50–100 times. The study of the dynamics of acid-soluble forms of Ni and Cu in the organic horizons of podzols on the key plots showed that the boundaries of polluted territory shift towards background regions despite the recent five–eightfold decrease in the emissions. The concentrations of heavy metals in the litter horizons continued to increase in the buffer zone. In the impact zone, their contamination remained at the very high level. Firm bounding of heavy metals in the organic horizon coupled with their continuing aerial input did not allow the beginning of the soil self-purification process, which might last for decades and centuries. Raster electron microscope and X-ray spectral microanalysis showed that particles (>85%) of the ashed matter of organic horizons from the background region, the buffer zone, and the impact zone is mainly represented by various soil-forming minerals and iron oxides (in particular, magnetite). In the samples from the impact zone, about 5% of the mineral particles had the surface morphology and chemical composition typical of dust particles emitted into the air by metal smelters. Most probably, these spherical particles represented magnetite Fe3O4 enriched in heavy metals (Cu, Ni). 相似文献
10.
湘中下寒武统黑色页岩土壤的地球化学特征 总被引：11，自引：0，他引：11
以湘中发育于下寒武统黑色页岩之上的土壤为研究对象,选择安化东坪、烟溪,桃江,宁乡等地的典型土壤及相应成土母岩,利用等离子质谱(ICP-MS)、X射线荧光光谱(XRF)等分析技术,对土壤、成土母岩(黑色页岩)的主量元素和微量元素(包括重金属元素、稀土元素等)进行了较系统的分析测定。结果表明,湘中下寒武统黑色页岩土壤风化作用强烈,风化指数CIA均在73以上。强烈的风化使得土壤具有明显贫CaO、Na2O,而富Al2O3、Fe2O3的化学组成特征。土壤因继承成土母岩(黑色页岩)的特征而富集Mo、Cd、Sn、Sb、U、V、Cr、Co、Ni、Cu、Zn、Tl、Pb、Th等多种重金属元素,其综合富集指数(EI值)平均在3以上,最高达17。地质累计指数(Igeo)评价结果显示,土壤重金属的富集已达到污染程度,土壤存在Cd、Mo、Sb、U、Sn、V、Cu、Tl、Ba等重金属的污染,并以Cd、Mo、Sb等重金属污染最强,达中度至极强污染程度。重金属与主量元素的相关性分析显示,土壤中的重金属主要赋存于黏土矿物和铁氧化物(针铁矿)等矿物相中,其中Ba、Sn、Th、Cu、Sc等主要赋存黏土矿物中;Zn、Ni、Mn、Co、Cd、Tl、Pb等则主要赋存于铁氧化物矿物(针铁矿)中;而Cr、V、Mo、Sb、U等则不受黏土矿物和铁氧化物矿物的控制。此外,不同地区土壤的Zr/Hf、Ta/Nb、Nd/Sm等元素比值相对稳定,依次为36.20、0.085、5.30(n=73),并与相应的成土母岩(黑色页岩)相应值基本一致。土壤与成土母岩具有相同的稀土配分型式,且成土过程中稀土元素不发生明显的分异。微量元素比值和稀土元素特征指示土壤中的重金属来自成土母岩(黑色页岩)本身,为自然污染源。 相似文献
11.
Yu. N. Vodyanitskii A. A. Vasil’ev A. T. Savichev A.N. Chashchin 《Eurasian Soil Science》2010,43(9):1011-1021
The content of heavy metals in the soils of the Middle CisUrals (the town of Chusovoi and its vicinities) is controlled by
both natural and technogenic factors. The enrichment of the parent rocks in Cr, Pb, Zn, and Cu, which influences the chemical
composition of the soils, is the most important among the natural factors. Among the other natural factors, the gleying and
washing of the alluvial soils with flood water are significant. The technogenic contamination of the urban soils reaches its
maximum in the technozems, where the content of Cu, Zn, Pb, and Cr exceeds their clarkes by 4–8 times. The index of technogeneity
(the share of technogenic metals referring to their total content) is high for the bulk of metals in technozems, in particular,
ranging within 36–97%. The technogeneity sequence is the following for the urban soils: Cr > Zn = Mn > Pb > Cu > Fe. The soil
contamination with metals is confined to the depression where the metallurgical plant is operating, and it significantly falls
already at a distance of 2–3 km in the settlements located at higher topographic positions. 相似文献
12.
Yu. N. Vodyanitskii I. O. Plekhanova E. V. Prokopovich A. T. Savichev 《Eurasian Soil Science》2011,44(2):217-226
The upper soil horizons are strongly contaminated in the area influenced by the Mid-Urals copper smelter. In the technogenic
desert and impact zones, the contents of a number of elements (Cu, Zn, As, Pb, P, and S) by many times exceed their clarke
values and the maximum permissible concentrations (or provisional permissible concentrations). The degree of technogeneity
(Tg) for these elements is very high in these zones. In the far buffer zone, Tg is about zero for many elements and increases
up to Tg = 27–42% for four heavy elements (Cu, Zn, Pb, and As) and up to 81–98% for P and S. The buffer capacity of the humus
horizon depends on the soil’s location within the technogeochemical anomaly and also on the particular pollutant. In the impact
zone, it is equal to 70–77% for lead and arsenic, although other technogenic elements (Zn, Cr, S, and P) are poorly retained
and readily migrate into the deeper horizons (the buffer capacity is equal to 14–25%). Nearly all the heavy metals enter the
soil in the form of sulfides. The soils in the area affected by the Noril’sk mining and smelting metallurgical enterprise
are subdivided into two groups according to the degree of their contamination, i.e., the soils within Noril’sk proper and
the soils in its suburbs to a distance of 4–15 km. The strongest soil contamination is recorded in the city: the clarke values
are exceeded by 287, 78, 16, 4.1, and 3.5 times for Cu, Ni, Cr, Fe, and S, respectively. The major pollutants enter the soil
from the ferruginous slag. The soil’s contamination degree is lower in the suburbs, where heavy metal sulfides reach the soils
with the aerial emission from the enterprise. 相似文献
13.
Barrado E. Prieto F. Lozano B. Arenas F. J. Medina J. 《Water, air, and soil pollution》2001,131(1-4):367-381
Waste water polluted with heavy metals can besuccessfully purified by precipitation of the metals from analkaline solution containing iron (II), giving rise to aferrite sludge. The solid metal ferrites obtained in thismanner can be used to remove hydrogen sulphide from a gasstream. Based on a Taguchi experimental design, ferrite solidparticle and pore size, and the temperature resulting inmaximum retention of H2S by the solid were optimised.Under the optimum conditions, predicted by the method, eachgram of ferrite was able to retain 0.274 g H2S.In addition, a ferrite containing a known lead concentration,obtained by the precipitation method under optimal conditionsof pH, temperature and Fe/Pb ratio, was used to study theexothermic H2S retention reaction. The chemical reactionoccurring between the ferrite and the H2S wasinvestigated by characterisation of the compounds before(Pb0.04FeII 0.96 FeIII 2O4·nH2O solids composed ofPbxFe3-xO4, magnetite Fe3O4 andhydrated lead oxide PbOn·H2O) and after (PbS, PbSO4, S, FeS2 and α-FeO(OH)) the retention process. 相似文献
14.
本文主要研究不同生物气候条件下由玄武岩母质发育的红壤、赤红壤和砖红壤的理化性质及矿物组成。粘粒中氧化铁的含量都很高,为16.98±0.83%。砖红壤与赤红壤粘粒中高岭石与非晶物质的含量相近,它们之间的差异是赤红壤中没有三水铝石,而含有7—11%蒙皂石。红壤粘粒中高岭石和非晶物质的含量都低于砖红壤和赤红壤,而水云母和蒙皂石的含量较高,也没有三水铝石。粘粒含量、阳离子交换量、硅铝率、硅铁铝率、铁的游离度和风化淋溶系数等都反映了土壤风化程度上的差异,它与水热条件特别是年均温和积温有关,进一步说明生物气候因素引起的土壤性质及矿物组成变化比其它因素强烈。砖红壤与砖红壤性水稻土的差异是在氧化铁形态上;红壤与红壤性水稻土相比,后者粘粒中蒙皂石含量略高,水云母含量略低。 相似文献
15.
D. Yu. Gruzdkov L. A. Shirkin T. A. Trifonova 《Moscow University Soil Science Bulletin》2009,64(4):182-188
Qualitative and quantitative studies of the kinetics and dynamics of technogenic migration of heavy metals (HMs) have been
performed in laboratory experiments. It is shown that the redistribution of HMs applied into soils in neutral form has an
impulsive pattern. Soil texture does not have a decisive influence on the migration capacity of metals. An important feature
of the technogenic migration of HMs is the effect of the polymetallic contamination, upon which the migration capacity of
a set of heavy metals is higher than that of separate metal compounds. An index characterizing the ratio of absolute values
of migration rates of ionic forms of metals estimated from electrical conductivity values to the rate of infiltration of the
soil solution (vm/vf) is suggested to estimate the kinetics of HM migration in soils. 相似文献
16.
Purpose
Identifying the spatial distribution and degree of heavy metal contamination in the soils is required for urban environmental management. Magnetic measurement provides a rapid means of determining spatial distribution and degree of soil pollution and identifying various anthropogenic sources of heavy metals. The purpose of this study was to characterize the magnetic signature of heavy metal contamination and identify the sources of heavy metals in urban soils from steel industrial city.Materials and methods
A total of 115 urban topsoils from Anshan city, Northeast China, were collected and determined for magnetic properties and heavy metal concentration. Magnetic susceptibility (χlf) and saturation isothermal remanent magnetization (SIRM) were determined as proxy for ferrimagnetic mineral concentration. Magnetic minerals were identified by using Curie temperature, X-ray diffraction (XRD), and scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS). The Pearson’ correlation and matrix cluster analyses were used to establish the relationship between magnetic parameters and heavy metal concentrations.Results and discussion
Urban topsoils exhibit characteristic magnetic enhancement. The magnetic measurement in particle size fractions indicates that 50–2 μm fraction has the highest low-field magnetic susceptibility (χlf), while <2 μm has the highest frequency-dependent magnetic susceptibility (χfd) value. The soil χlf and SIRM values are significantly correlated with the contents of metals (Fe, Pb, Zn, Cu, and Cr) and Tomlinson pollution load index (PLI), which indicates that χlf and SIRM could be served as better indicators for the pollution of heavy metals in the urban topsoil. Spatial distribution maps of χlf, SIRM, and PLI indicate that the pollution hotspots tend to associate with the regions within and close to steel industrial zones. XRD and Curie temperature analyses indicate that the main magnetic minerals of urban topsoils are magnetite (Fe3O4), hematite (α-Fe2O3), and metallic iron. Magnetic minerals mostly occur in the pseudo-single-domain/multidomain (PSD/MD) grain size range, which is the dominant contributor to the magnetic enhancement of topsoils. SEM observation reveals that magnetic particles in soils exist in irregular-shaped particles and spherule. Results reveal that heavy metals from industrially derived and traffic emissions coexist with coarse-grained magnetic phases.Conclusions
It is concluded that the magnetic measurement could be regarded as a proxy tool to detect the level of heavy metal pollution and identify the source of heavy metals in urban soils. Magnetic properties provide a fast and inexpensive method to map the spatial distribution of long-term pollution from steel industrial origin on region scale.17.
Saglara S. Mandzhieva Tatiana M. Minkina Victor A. Chaplygin Tatiana V. Bauer Marina V. Burachevskaya Dina G. Nevidomskaya Svetlana N. Sushkova Aleksey K. Sherstnev Inna V. Zamulina 《Journal of Soils and Sediments》2017,17(5):1291-1300
Purpose
The aim of this work was to select and assess the efficiency of different amendments applied to ordinary chernozems artificially contaminated with heavy metals (Zn and Pb).Materials and methods
The effect of different amendments on ordinary chernozem contaminated with Zn and Pb acetate salts was studied in a long-term 3-year field experiment. Glauconite, chalk, manure, and their combinations were chosen as ameliorating agents. Spring barley (Hordeum sativum) was used as test culture for three successive years. The heavy metal concentration in all the soil samples decomposed by HF?+?HClO4 was determined by atomic absorption spectrophotometry (AAS). One normal concentration of CH3COONH4 at pH 4.8 was used to estimate the actual mobility of metals. The compounds of heavy metals extracted by 1 N HCl are regarded as mobile compounds. The concentration of metals in the plants was determined using the dry combustion in a mixture of HNO3 and HCl at 450 °C. The content of heavy metals in extracts from soil and plant samples was determined by AAS.Results and discussion
The content of weakly bound metal compounds increased upon the contamination of the soil with Pb and Zn salts, which led to a low quality of barley grown in these soils. Metal concentrations in the barley grain exceeded the maximum permissible concentrations (MPCs). The content of Zn and Pb in grains was higher than the MPC for at least 3 years after the soil pollution. The application of amendments significantly decreased the mobility of metals, and the simultaneous application of chalk and manure was most significant. The share of weakly bound metal compounds in the contaminated soils decreased to the level typical for the clean soils or even below.Conclusions
The combined application of chalk and manure to Zn- and Pb-contaminated ordinary chernozems decreased the content of weakly bound metal compounds in the soil and lowered their concentrations in barley plants. The polyfunctional properties of the soil components with respect to their capacity for metal fixation were established. The decrease in the intensity of Zn accumulation in grains of barley shows the presence of a barrier at the root–stalk and stalk–grain interfaces.18.
A methodological approach for determining barium, lanthanum, and cerium contents with the use of an 241Am isotope source was suggested. The new method was applied for obtaining data on the geochemistry of Ba, La, and Ce in soils
of humid landscapes. The high content of La and Ce was determined in cryozems of the Kolyma Lowland. In alluvial soils of
Perm’, barium was identified in rhyzoconcretions in the form of barium sulfate of probably technogenic origin. In the gleyed
agrozem on the Mulyanka River floodplain, the redistribution of barium in the soil profile and its concentration in iron nodules
were detected. The contents of La and Ce in the fine earth of contaminated soils remained stable, and lanthanides were accumulated
in concretions: the coefficient of La accumulation was 3.5 and that of Ce was 6.9. The mean accumulation coefficients of the
elements in the studied soils were as follows: Ce (3.7) > Ba (3.0) > La (2.2). 相似文献
19.
《Communications in Soil Science and Plant Analysis》2012,43(17):2314-2322
Chemical speciation and bioaccumulation factor of iron (Fe), manganese (Mn), and zinc (Zn) were investigated in the fractionated rhizosphere soils and tissues of sunflower plants grown in a humic Andosol. The experiment was conducted for a period of 35 days in the greenhouse, and at harvest the soil system was differentiated into bulk, rhizosphere, and rhizoplane soils based on the collection of root-attaching soil aggregates. The chemical speciations of heavy metals in the soil samples were determined after extraction sequentially into fractions classified as exchangeable, carbonate bound, metal–organic complex bound, easily reducible metal oxide bound, hydrogen peroxide (H2O2)–extractable organically bound, amorphous mineral colloid bound, and crystalline Fe oxide bound. Iron and Zn were predominantly crystalline Fe oxide bound in the initial bulk soils whereas Mn was mainly organically bound. Heavy metals in the exchangeable form accumulated in the rhizosphere and rhizoplane soils, comprising <4% of the total content, suggesting their relatively low availability in humic Andosol. Concentrations of organically bound Fe and Mn in soils decreased with the proximity to roots, suggesting that organic fraction is the main source for plant uptake. Concentrations of Mn and Zn in the metal–organic complex also decreased, indicating a greater ability of sunflower to access Mn from more soil pools. Sunflower showed bioaccumulation factors for Zn, Fe, and Mn as large as 0.39, 0.05, and 0.04 respectively, defining the plant as a metal excluder species. This result suggests that access to multiple metal pools in soil is not necessarily a major factor that governs metal accumulation in the plant. 相似文献
20.
《Communications in Soil Science and Plant Analysis》2012,43(3-4):347-361
Abstract The accumulation of heavy metals in plants is related to concentrations andchemical fractions of the metals in soils. Understanding chemical fractions and availabilities of the metals in soils is necessary for management of the soils. In this study, the concentrations of copper (Cu), cadmium (Cd), lead (Pb), and zinc (Zn) in tea leaves were compared with the total and extractable contents of these heavy metals in 32 surface soil samples collected from different tea plantations in Zhejiang province, China. The five chemical fractions (exchangeable, carbonate‐bound, organic matter‐bound, oxides‐bound, and residual forms) of the metals in the soils were characterized. Five different extraction methods were also used to extract soil labile metals. Total heavy metal contents of the soils ranged from 17.0 to 84.0 mgCukg?1, 0.03 to 1.09 mg Cd kg?1, 3.43 to 31.2 mg Pb kg?1, and 31.0 to 132.0 mg Zn kg?1. The concentrations of exchangeable and carbonate‐bound fractions of the metals depended mainly on the pH, and those of organic matter‐bound, oxides‐bound, and residual forms of the metals were clearly controlled by their total concentrations in the soils. Extractable fractions may be preferable to total metal content as a predictor of bioconcentrations of the metals in both old and mature tea leaves. The metals in the tea leaves appeared to be mostly from the exchangeable fractions. The amount of available metals extracted by 0.01 mol L?1 CaCl2, NH4OAc, and DTPA‐TEA is appropriate extractants for the prediction of metals uptake into tea plants. The results indicate that long‐term plantation of tea can cause sol acidification and elevated concentrations of bioavailable heavy metals in the soil and, hence, aggravate the risk of heavy metals to tea plants. 相似文献