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Assessment of isoto...
Assessment of isotopically exchangeable Al in soil materials using Al-26 tracer
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Kleja, D. B. (författare)
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Standring, W. (författare)
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Oughton, D. H. (författare)
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- Gustafsson, Jon Petter (författare)
- KTH,Miljögeokemi och ekoteknik
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Fifield, K. (författare)
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Fraser, A. R. (författare)
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(creator_code:org_t)
- Elsevier BV, 2005
- 2005
- Engelska.
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 69:22, s. 5263-5277
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- The solubility of aluminium (Al) in many acidic soils is controlled by complexation reactions with soil organic matter. In such soils, Al solubility is theoretically a function of the pool size of active Al, i.e., the total amount of Al that equilibrates with the sod solution within a defined period of time. To date, no reliable measurements of active Al in soil materials exist. In this study, we determined the isotopically exchangeable pool of Al (E-A1) as an operationally defined assessment of active Al in acidic mineral soils. The suitability of CuCl2 and pyrophosphate (Na4P2O7) as extractants for active Al was also evaluated. Eleven samples, mostly from spodic B horizons, were spiked with carrier-free Al-26 and equilibrated for different time periods (1-756 h). The size of the Al pool with which the Al-26 tracer exchanged increased with time during the whole experimental period. Thus, contact time between solid and solution phases needs to be defined when assessing the active Al pool. Values of E-A1 obtained after I to 5 d of equilibration were equal to the amount of CuCl2 extractable Al, but considerably smaller than the Na4P2O7-extractable pool. Equilibration times greater than 5 d resulted in CuCl2 extractable Al concentrations that under-estimated the active Al pool. Three of the investigated samples were rich in imogolite-type materials (ITM). In these samples, 30-50 % of the added Al-26 rapidly became associated with soil constituents in forms that could not be extracted by Na4P2O7, indicating that a part of ITM may be in a dynamic state.
Nyckelord
- accelerator mass-spectrometry
- aluminum solubility mechanisms
- quickly reacting aluminum
- podzol bs horizon
- organic-matter
- humic substances
- forest soils
- equilibrium-model
- aqueous-solution
- acid soils
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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