Use of Single and Sequential Chemical Extractants to Assess Radionuclide and Heavy Metal Availability From Soils for Root Uptake

Kennedy, V. H.; Sanchez, Anthony; Oughton, Deborah; Rowland, A. P.

doi:10.1039/a704133k

Cited by 238 publications

(120 citation statements)

References 43 publications

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“…However, when the soils were air-dried some of their chemical and physical properties may be altered. Such changes may be unimportant to total concentration but can significantly affect the speciation of trace elements in soils (Kennedy et al, 1997). Therefore, the veracity of using dried soil samples for the speciation analysis and bioavailability should be reconsidered.…”

Section: Speciation Difference Between Air-dried and Wet Samplesmentioning

confidence: 99%

“…Rhizosphere is a small but important subsystem of pedosphere, and the properties of rhizosphere are different largely from those of bulk soils (Kraffczyk et al, 1984;Curl and Truelove, 1986). It also seems that there are different speciations present in dried and wet soils (Kennedy et al, 1997). The aim of this study is to compare the elemental speciation and bioavailability between the rhizoshphere soils and bulk soils.…”

Section: Introductionmentioning

confidence: 99%

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Comparison between fractionation and bioavailability of trace elements in rhizosphere and bulk soils

2002

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Rhizosphere is a microbiosphere and has quite different chemical, physical and biological properties from bulk soils. A greenhouse experiment was performed to compare the difference of fractionation and bioavailability of trace elements Cr, Ni, Zn, Cu, Pb and Cd between rhizosphere soil and bulk soil. In the meantime, the influence of air-drying on the fractionation and bioavailability was also investigated by using wet soil sample as a control. Soils in a homemade rhizobox were divided into four zones: rhizosphere, near rhizosphere, near bulk soil and bulk soil zones, which was designated as S 1 , S 2 , S 3 and S 4 . Elemental speciations were fractionated to water soluble, exchangeable and carbonate bound (B1), Fe-Mn oxide bound (B2), and organic and sulfide bound (B3) by a sequential extraction procedure. Speciation differences were observed for elements Cr, Ni, Zn, Cu, Pb and Cd between the rhizosphere and bulk soils, and between the air-dried and wet soils as well. The concentrations of all six heavy metals in fraction B1 followed the order of S 2 > S 3 > S 1 > S 4 and for B2, the order was S 2 > S 3 % S 4 > S 1 . For B3, the order was S 1 > S 3 % S 4 > S 2 , while for Cd the order was S 2 > S 3 % S 4 > S 1 . The air-drying increased elemental concentration in fractions B1 and B2 by 20-50% and decreased in fraction B3 by about 20-100%. Correlation analysis also indicated that the bioavailability correlation coefficient of fraction B1 in rhizosphere wet soil to plants was better than that between either air-dried or nonrhizosphere soils. Therefore, application of rhizosphere wet soils should be recommended in the future study on the speciation analysis of trace elements in soils and bioavailability. Ó

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Section: Speciation Difference Between Air-dried and Wet Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison between fractionation and bioavailability of trace elements in rhizosphere and bulk soils

2002

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“…Many studies have shown that chemical extraction procedures can measure the metals in soil pools potentially available for plant uptake and/or accumulation (Kennedy et al, 1997). Single extraction methods were based on the assumption that there is a relationship between the extractable fraction of metals and the phytoavailability of metals to plants, i.e., a good correlation indicated that a certain fraction of the total metal in the soils was available to plants.…”

Section: Evaluation Of the A-rhizo Methods Based On A Comparison With mentioning

confidence: 99%

Is an adjusted rhizosphere-based method valid for field assessment of metal phytoavailability? Application to non-contaminated soils

Fang

Wen

Shan

et al. 2007

Environmental Pollution

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An adjusted-RHIZO method was the most promising approach for predicting metal phytoavailability to wheat under field conditions. AbstractPreviously recommended rhizosphere-based method (RHIZO) applied to moist rhizosphere soils was integrated with moist bulk soils, and termed adjusted-RHIZO method (A-RHIZO). The A-RHIZO and RHIZO methods were systematically compared with EDTA, DTPA, CaCl 2 and the first step of the Community Bureau of Reference (BCR1) methods for assessing metal phytoavailability under field conditions. Results suggested that moist bulk soils are equally suited or even better than rhizosphere soils to estimate metal phytoavailability. The A-RHIZO method was preferred to other methods for predicting the phytoavailability of Ni, Cu, Zn, Cd, Pb and Mn to wheat roots with correlation coefficients of 0.730 (P < 0.001), 0.854 (P < 0.001), 0.887 (P < 0.001), 0.739 (P < 0.001), 0.725 (P < 0.001) and 0.469 (P < 0.05), respectively. When including soil properties, other extraction methods were also able to predict phytoavailability reasonably well for some metals. Soil pH, organic matter and FeeMn oxide contents, and cation-exchange capacity mostly influenced the extraction and phytoavailability of metals.

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“…Due to analytical difficulties, traditional methods for determining the speciation of U, and other metals, in sediments have relied primarily on chemical extraction techniques (Table 1), in which various phases within the matrix are operationally defined and interferences on chemical associations are generated [45]. Many different sequential extraction schemes have been developed (see reviews by Kersten and Förstner [46] and Kennedy et al [47]). Chemical extraction techniques have been used, among other things, to indicate the fraction of total U in the sediment that is weak acid soluble (e.g., 0.1 to 1 M HNO 3 or HCl).…”

Section: Sedimentmentioning

confidence: 99%

Uranium Speciation and Bioavailability in Aquatic Systems: An Overview

Markich

2002

The Scientific World JOURNAL

203

142

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The speciation of uranium (U) in relation to its bioavailability is reviewed for surface waters (fresh-and seawater) and their sediments. A summary of available analytical and modeling techniques for determining U speciation is also presented. U(VI) is the major form of U in oxic surface waters, while U(IV) is the major form in anoxic waters. The bioavailability of U (i.e., its ability to bind to or traverse the cell surface of an organism) is dependent on its speciation, or physicochemical form. U occurs in surface waters in a variety of physicochemical forms, including the free metal ion (U 4+ or UO 2 2+ ) and complexes with inorganic ligands (e.g., uranyl carbonate or uranyl phosphate), and humic substances (HS) (e.g., uranyl fulvate) in dissolved, colloidal, and/or particulate forms. Although the relationship between U speciation and bioavailability is complex, there is reasonable evidence to indicate that UO 2 2+ and UO 2 OH + are the major forms of U(VI) available to organisms, rather than U in strong complexes (e.g., uranyl fulvate) or adsorbed to colloidal and/or particulate matter. U(VI) complexes with inorganic ligands (e.g., carbonate or phosphate) and HS apparently reduce the bioavailability of U by reducing the activity of UO 2 2+ and UO 2 OH + . The majority of studies have used the results from thermodynamic speciation modeling to support these conclusions. Time-resolved laser-induced fluorescence spectroscopy is the only analytical technique able to directly determine specific U species, but is limited in use to freshwaters of low pH and ionic strength. Nearly all of the available information relating the speciation of U to its bioavailability has been derived using simple, chemically defined experimental freshwaters, rather than natural waters. No data are available for estuarine or seawater. Furthermore, there are no available data on the relationship between U speciation and bioavailability in sediments. An understanding of this relationship has been hindered due to the lack of direct quantitative U speciation techniques for particulate phases. More robust analytical techniques for determining the speciation of U in natural surface waters are needed before the relationship between U speciation and bioavailability can be clarified.

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Use of Single and Sequential Chemical Extractants to Assess Radionuclide and Heavy Metal Availability From Soils for Root Uptake

Cited by 238 publications

References 43 publications

Comparison between fractionation and bioavailability of trace elements in rhizosphere and bulk soils

Comparison between fractionation and bioavailability of trace elements in rhizosphere and bulk soils

Is an adjusted rhizosphere-based method valid for field assessment of metal phytoavailability? Application to non-contaminated soils

Uranium Speciation and Bioavailability in Aquatic Systems: An Overview

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