Speciation of particulate-bound Cadmium of soils and its bioavailability

Krishnamurti, G. S. R.; Huang, P. M.; Rees, K. C. J. Van; Kozak, L. M.; Rostad, H. P. W.

doi:10.1039/an9952000659

Cited by 147 publications

(73 citation statements)

References 19 publications

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“…The total Cd content and the Cd availability index (CAl) of the soils were determined following the microwave digestion technique (Krishnamurti et al, 1994) and the M NH 4 Cl extraction technique (Krishnamurti et al, 1995b ), respectively. The speciation of particulate-bound Cd of both the bulk and rhizosphere soils was carried out using the selective sequential extraction scheme of Krishnamurti et al ( 1995a). Cadmium in the digestion extracts of the soils was determined using a Perkin Elmer 2280 electrothermal atomic absorption spectrometer at 228.8 nm using a pyrolytically-coated tube and L'vov platform.…”

Section: Methodsmentioning

confidence: 99%

Studies on soil rhizosphere: speciation and availability of Cd

Krishnamurti

Huang

Rees

1996

Chemical Speciation & Bioavailability

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The rhizosphere soils of two durum wheat (Triticum turgidum var. durum L.) cultivars Kyle and Arcola grown in two selected soils of southern Saskatchewan were collected both at 2-week and 7-week plant growth stages. The cadmium availability index (CAl), determined as M NH 4 CI-extractable Cd, pH and the distribution of the particulatebound Cd species of the soils were carried out and the data were discussed in comparison with those of the corresponding bulk soil. At the 2-week growth stage, the pH of the rhizosphere soil was less than that of the corresponding bulk soil and the CAl values were higher in the rhizosphere soil, indicating that more Cd was complexed with the low-molecular-weight organic acids (LMWOAs) at the soil-root interface and was extractable by M NH 4 CI. Compared with the bulk soils, the CAl values were 2-9 times higher in the soil rhizosphere of the plots fertilized with Idaho monoammonium phosphate fertilizer at 2-week growth stage, which is attributed to the combined effects of the Cd introduced into the soil rhizosphere from the fertilizer (Cd content of the fertilizer was 144 mg kg-1) and complexation reactions of phosphate and LMWOAs with soil Cd. At 7-week plant growth stage, such differences were not observed. The increased amounts of carbonate-bound and metal-organic complex-bound Cd species of the rhizosphere soils are due to the increased amounts of carbonate, a product of plant respiration, and the LMWOAs at the soil-root interface, respectively. Simple correlation analysis of the data showed that the CAl of the rhizosphere soils of the control plots correlated at least two orders of magnitude better with the metal-organic complex-bound Cd whereas the CAl of the rhizosphere soils treated with Idaho phosphate correlated better with carbonate-bound Cd species in comparison to other species.

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Section: Methodsmentioning

confidence: 99%

Studies on soil rhizosphere: speciation and availability of Cd

Krishnamurti

Huang

Rees

1996

Chemical Speciation & Bioavailability

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“…Total concentrations of metals in soils are a poor indicator of metal toxicity since metals exist in different solid-phase forms that can vary greatly in terms of their bioavailability (Krishnamurti et al, 1995;Krishnamurti and Naidu;Huang and Gobran, 2005;Violante et al, 2010). Therefore the determination of total soil metal content alone is not a good measure of bioavailability and not a very useful tool to quantify contamination and potential environmental and human health risk (Violante et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Distribution of different fractions of Iron, Zinc, Chromium, lead and Nickel in Soils around Petrol filling stations in selected Areas of Delta State, Nigeria

Osakwe¹,

Okolie²

2016

Journal of Applied Sciences and Environmental Management

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ABSTRACT:The geochemical forms of some heavy metals in soils around selected petrol filling stations were studied in order to assess the mobility and bioavailability of the metals and hence their potential environmental risk. Water soluble fraction (F 1 ) contained an average of 0.97% iron, 1.40% zinc, 2.37% chromium, 2.08% lead and 41.96% nickel with the abundance trend of Ni > Cr > Pb > Zn > Fe. Metal bound to exchangeable phase followed the same abundance trend with an average of 6.46% nickel, 5.48% chromium, 2.64% lead, 2.55% zinc and 0.62% iron. Lead was predominantly associated with carbonate fraction with an average of 52.32% followed by iron with an average of 15.41%. Other metal average levels in the carbonate fractions were 9.66% for nickel, 8.78% for chromium, and 8.73% for zinc giving the abundance trend of Pb > Fe > Ni > Cr > Zn. The most important metal in iron-manganese oxide phase was zinc with an average of 42.49%, followed by iron with an average of 32.82%. The averages of the other metals bound to this phase were 30.39%, 13.24% and 6.46% for chromium, lead and nickel respectively. The organic bound metals were in the abundance trend of Fe > Zn > Cr > Pb > Ni with average of 39.48% for iron, 30.87% for zinc, 23.03% for chromium, 8.54% for lead and 4.94% for nickel. Nickel with an average of 51.58% was predominantly associated with the residual fraction. The other metals bound to this phase in order of their importance to the fraction had the average of 22.75% for chromium, 13.96% for zinc, 12.24% for lead and 10.97% for iron. The mobility factor values of the metals were moderately high with the abundance trend of Pb > Ni > Cr > Fe > Zn. The generally low levels of the metals in the residual fraction coupled with the mobility factor trend suggest potential risk for the metals. ©JASEM

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“…Humic acids have a substantial capacity to complex metal ions, and the complexation process may affect the solubility of the metal ions (Zhang et al 1996). Studies on the speciation of particulate-bound Cd in temperate (Krishnamurti et al 1995) and tropical (Onyatta and Huang 1999) soils indicate that the metal-organic com-plex-bound Cd is highly correlated with the bioavailability index of Cd. On the other hand, it was reported that adding HA to soils reduces the bioavailability of Cd (Taylor and Theng 1995;Shuman 1998); the nature of the soil's organic matter apparently influences this attribute.…”

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confidence: 99%

Sorption of cadmium on humic acid: Mechanistic and kinetic studies with atomic force microscopy and X-ray absorption fine structure spectroscopy

Liu¹,

Frenkel²,

Vairavamurthy³

et al. 2001

Can. J. Soil. Sci.

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. 2001. Sorption of cadmium on humic acid: Mechanistic and kinetic studies with atomic force microscopy and X-ray absorption fine structure spectroscopy. Can. J. Soil Sci. 81: 337-348. Humic acids (HA) constitute a major fraction of the organic matter in soils and sediments. Little is known about the kinetics and mechanisms of Cd sorption by HAs, especially those pertaining to the surface features and structure of the Cd-humate complexes. We investigated Cd sorption by HA using the conventional batch method, N 2 -BET method, atomic force microscopy (AFM), and extended X-ray absorption fine structure (EXAFS) spectroscopy to gain a better understanding of the kinetics and mechanisms. Cadmium sorption by HA can be described by the parabolic diffusion equation. The increase in the apparent diffusion coefficient with an increase in the initial Cd concentration was less pronounced at higher initial Cd concentrations, apparently due to an enhancement in aggregation of the Cd-humate complexes. The HA before and after Cd sorption at Cd concentrations ≤ 10 -6 M in different reaction times was spheroidal in shape. The Cd-humate complexes formed at 10 -4 and 10 -3 M Cd gradually changed to resemble the shape of a bean with increasing reaction time, thereby substantially decreasing their specific surface. Cadmium ions raveled the spheroidal HA particles into a bean-like structure by coordinating to six O atoms from the functional groups of HA, with a Cd-O distance of 2.297(2) Å. The Cd-O bond strength decreased with increasing initial Cd concentration.Key words: Cadmium, humate complexes, conformation, atomic force microscopy, EXAFS Liu, C., Frenkel, A. I., Vairavamurthy, A. et Huang, P. M. 2001. Étude de la mécanique et de la cinétique de la sorption du cadmium par l'acide humique au moyen de la microscopie à force atomique et de la spectroscopie des structures fines par absorption des rayons X. Can. J. Soil Sci. 81: 337-348. Les acides humiques (AH) constituent une bonne partie de la matière organique présente dans le sol et les sédiments. On sait peu de choses sur la cinétique et la mécanique de la sorption du Cd par les AH, surtout en relation avec les propriétés de la surface et la structure des complexes Cd-humate. Les auteurs ont étudié la sorption du Cd par les AH selon la méthode par lots traditionnelle, la technique N 2 -BET, la microscopie à force atomique (MFA) et une variante de la spectroscopie des structures fines par absorption des rayons X (EXAFS) dans l'espoir de mieux comprendre la cinétique et la mécanique du phénomène. L'équation de diffusion parabolique décrit la sorption du cadmium par les AH. La hausse du coefficient de diffusion apparent associée à l'augmentation de la concentration initiale de Cd est moins importante quand la concentration initiale de Cd est plus élevée. On le doit apparemment à une meilleure agrégation des complexes Cd-humate. Les AH présentent une forme sphéroïdale avant et après la sorption du Cd (concentration ≤ 10-6 M) à divers temps de réaction. Les complexes Cd-humate qui voi...

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Speciation of particulate-bound Cadmium of soils and its bioavailability

Cited by 147 publications

References 19 publications

Studies on soil rhizosphere: speciation and availability of Cd

Studies on soil rhizosphere: speciation and availability of Cd

Distribution of different fractions of Iron, Zinc, Chromium, lead and Nickel in Soils around Petrol filling stations in selected Areas of Delta State, Nigeria

Sorption of cadmium on humic acid: Mechanistic and kinetic studies with atomic force microscopy and X-ray absorption fine structure spectroscopy

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