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| 2. |
- Sarneel, Judith M., et al.
(författare)
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Reading tea leaves worldwide : decoupled drivers of initial litter decomposition mass-loss rate and stabilization
- 2024
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Ingår i: Ecology Letters. - : John Wiley & Sons. - 1461-023X .- 1461-0248. ; 27:5
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Tidskriftsartikel (refereegranskat)abstract
- The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models.
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| 3. |
- Villen-Guzman, Maria, et al.
(författare)
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Effects of the buffering capacity of the soil on the mobilization of heavy metals. Equilibrium and kinetics.
- 2015
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Ingår i: Chemosphere. - : Elsevier BV. - 1879-1298 .- 0045-6535. ; 131, s. 78-84
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the possible pH-buffering processes is of maximum importance for risk assessment and remediation feasibility studies of heavy-metal contaminated soils. This paper presents the results about the effect of the buffering capacity of a polluted soil, rich in carbonates, on the pH and on the leaching evolution of its main contaminant (lead) when a weak acid (acetic acid) or a strong one (nitric acid) are slowly added. In both cases, the behavior of lead dissolution could be predicted using available (scientifically verified freeware) models assuming equilibrium between the solid and the aqueous phase. However, the experimental results indicate that the dissolution of calcium and magnesium carbonates is kinetically controlled. These kinetic limitations affect the overall behavior, and should be considered to understand also the response of the metals under local equilibrium. The well-known BCR sequential extraction procedure was used before- and after-treatment, to fractionate the lead concentration in the soil according to its mobility. The BCR results were also in agreement with the predictions of the equilibrium model. This agreement allows new insights about the information that could be derived from the BCR fractionation analysis.
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| 4. |
- Villen-Guzman, Maria, et al.
(författare)
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Scaling-up the acid-enhanced electrokinetic remediation of a real contaminated soil
- 2015
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 181, s. 139-145
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Tidskriftsartikel (refereegranskat)abstract
- Although there is a lot of experimental work published about the use of Electrokinetic Remediation for the removal of toxic metals from soils, very few have reported results for different scales. Scaling- up is a difficult task, since the behavior of each metal is different and is also site-specific. In this paper we present a convenient parameter for the comparison of the energy requirements at different scales. This parameter consists on the definition of a specific-energy for each metal, based on the amount mobilized and the maximum removal expected as determined from the BCR fractionation analysis. The tests, which were carried out with soil columns holding soil samples of 16 g and with soil samples of 2000 g, are giving similar values of this parameter. Our results indicate that this specific-energy depends on the target metal to be recovered, but for each metal is quite similar for the experimental conditions of the two scales essayed. These conditions included that the initial electrical resistivity times the column length were equal for the two scales. A simple mathematical model predicts these results, and that for equal resistivity the specific energy requirement will be proportional to the distance between electrodes. (C) 2015 Elsevier Ltd. All rights reserved.
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