Erlandsson, M;
Oelkers, EH;
Bishop, K;
Sverdrup, H;
Belyazid, S;
Ledesma, JLJ;
Köhler, SJ;
(2016)
Spatial and temporal variations of base cation release from chemical weathering on a hillslope scale.
Chemical Geology
, 441
pp. 1-13.
10.1016/j.chemgeo.2016.08.008.
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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 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.
Type: | Article |
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Title: | Spatial and temporal variations of base cation release from chemical weathering on a hillslope scale |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1016/j.chemgeo.2016.08.008 |
Publisher version: | http://dx.doi.org/10.1016/j.chemgeo.2016.08.008 |
Language: | English |
Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
Keywords: | Mineral dissolution kinetics; PROFILE; Transition-State-Theory; PHREEQC; Acidification; Riparian zone |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
URI: | https://discovery.ucl.ac.uk/id/eprint/1508638 |
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