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Spatial and temporal variations of base cation release from chemical weathering on a hillslope scale

Erlandsson, M.; Oelkers, E. H.; Bishop, K.; Sverdrup, H.; Belyazid, S. LU ; Ledesma, J. L J and Köhler, S. J. (2016) In Chemical Geology 441. p.1-13
Abstract

Cation release rates to catchment runoff from chemical weathering were assessed using an integrated catchment model that included the soil's unsaturated, saturated and riparian zones. In-situ mineral dissolution rates were calculated in these zones as a function of pH, aluminum and dissolved organic carbon (DOC) concentrations along a hillslope in Northern Sweden where soil water was monitored over nine years. Three independent sets of mineral dissolution equations of varying complexity were used: PROFILE, Transition-State Theory (TST), and the Palandri & Kharaka database. Normalization of the rate-coefficients was necessary to compare the equations, as published rate-coefficients gave base cation release rates differing by several... (More)

Cation release rates to catchment runoff from chemical weathering were assessed using an integrated catchment model that included the soil's unsaturated, saturated and riparian zones. In-situ mineral dissolution rates were calculated in these zones as a function of pH, aluminum and dissolved organic carbon (DOC) concentrations along a hillslope in Northern Sweden where soil water was monitored over nine years. Three independent sets of mineral dissolution equations of varying complexity were used: PROFILE, Transition-State Theory (TST), and the Palandri & Kharaka database. Normalization of the rate-coefficients was necessary to compare the equations, as published rate-coefficients gave base cation release rates differing by several orders of magnitude. After normalizing the TST- and Palandri & Kharaka-rate coefficients to match the base cation release rates calculated from the PROFILE-equations, calculated Ca2 + and Mg2 + release rates are consistent with mass balance calculations, whereas those of Na+ and K+ are overestimated. Our calculations further indicate that a significant proportion of base cations are released from the organic soils in the near-stream zone, in part due to its finer texture. Of the three sets of rate equations, the base cation release rates calculated from the normalized TST-equations were more variable than those calculated using the other two sets of equations, both spatially and temporally, due to its higher sensitivity to pH. In contrast, the normalized Palandri & Kharaka-equations were more sensitive to variations in soil temperature.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Acidification, Mineral dissolution kinetics, PHREEQC, PROFILE, Riparian zone, Transition-State-Theory
in
Chemical Geology
volume
441
pages
13 pages
publisher
Elsevier
external identifiers
  • Scopus:84981507172
ISSN
0009-2541
DOI
10.1016/j.chemgeo.2016.08.008
language
English
LU publication?
yes
id
d9ea1430-1a3e-457e-a46c-3e1300b3269f
date added to LUP
2016-10-12 14:15:22
date last changed
2016-10-12 14:15:22
@misc{d9ea1430-1a3e-457e-a46c-3e1300b3269f,
  abstract     = {<p>Cation release rates to catchment runoff from chemical weathering were assessed using an integrated catchment model that included the soil's unsaturated, saturated and riparian zones. In-situ mineral dissolution rates were calculated in these zones as a function of pH, aluminum and dissolved organic carbon (DOC) concentrations along a hillslope in Northern Sweden where soil water was monitored over nine years. Three independent sets of mineral dissolution equations of varying complexity were used: PROFILE, Transition-State Theory (TST), and the Palandri &amp; Kharaka database. Normalization of the rate-coefficients was necessary to compare the equations, as published rate-coefficients gave base cation release rates differing by several orders of magnitude. After normalizing the TST- and Palandri &amp; Kharaka-rate coefficients to match the base cation release rates calculated from the PROFILE-equations, calculated Ca<sup>2 +</sup> and Mg<sup>2 +</sup> release rates are consistent with mass balance calculations, whereas those of Na<sup>+</sup> and K<sup>+</sup> are overestimated. Our calculations further indicate that a significant proportion of base cations are released from the organic soils in the near-stream zone, in part due to its finer texture. Of the three sets of rate equations, the base cation release rates calculated from the normalized TST-equations were more variable than those calculated using the other two sets of equations, both spatially and temporally, due to its higher sensitivity to pH. In contrast, the normalized Palandri &amp; Kharaka-equations were more sensitive to variations in soil temperature.</p>},
  author       = {Erlandsson, M. and Oelkers, E. H. and Bishop, K. and Sverdrup, H. and Belyazid, S. and Ledesma, J. L J and Köhler, S. J.},
  issn         = {0009-2541},
  keyword      = {Acidification,Mineral dissolution kinetics,PHREEQC,PROFILE,Riparian zone,Transition-State-Theory},
  language     = {eng},
  month        = {11},
  pages        = {1--13},
  publisher    = {ARRAY(0x89f7f60)},
  series       = {Chemical Geology},
  title        = {Spatial and temporal variations of base cation release from chemical weathering on a hillslope scale},
  url          = {http://dx.doi.org/10.1016/j.chemgeo.2016.08.008},
  volume       = {441},
  year         = {2016},
}