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Catchment export of base cations: improved mineral dissolution kinetics influence the role of water transit time

Erlandsson Lampa, Martin and Sverdrup, Harald U. and Bishop, Kevin and Belyazid, Salim and Ameli, Ali and Köhler, Stephan (2020). Catchment export of base cations: improved mineral dissolution kinetics influence the role of water transit time. Soil. 6 , 231-244
[Journal article]

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Abstract

Soil mineral weathering is one of the major sources of base cations (BC), which play a dual role in forest ecosystems: they function as plant nutrients and buffer against the acidification of catchment runoff. On a long-term basis, soil weathering rates determine the highest sustainable forest productivity that does not cause acidification. It is believed that the hydrologic residence time plays a key role in determining the weathering rates at the landscape scale.The PROFILE weathering model has been used for almost 30 years to calculate weathering rates in the rooting zone of forest soils. However, the mineral dissolution equations in PROFILE are not adapted for the saturated zone, and employing these equations at the catchment scale results in a significant overprediction of base cation release rates to surface waters. In this study, we use a revised set of PROFILE equations which, among other features, include retardation due to silica concentrations. Relationships between the water transit time (WTT) and soil water concentrations were derived for each base cation, by simulating the soil water chemistry along a one-dimensional flow path, using the mineralogy from a glacial till soil. We show how the revised PROFILE equations are able to reproduce patterns in BC and silica concentrations as well as BC ratios (Ca2+/BC, Mg2+/BC and Na+/BC) that are observed in the soil water profiles and catchment runoff. In contrast to the original set of PROFILE equations, the revised set of equations could reproduce the fact that increasing WTT led to a decreasing Na+/BC ratio and increasing Ca2+/BC and Mg2+/BC ratios. Furthermore, the total release of base cations from a hillslope was calculated using a mixing model, where water with different WTTs was mixed according to an externally modeled WTT distribution. The revised set of equations gave a 50% lower base cation release (0.23 eqm 2 yr 1) than the original PROFILE equations and are in better agreement with mass balance calculations of weathering rates. Thus, the results from this study demonstrate that the revised mineral dissolution equations for PROFILE are a major step forward in modeling weathering rates at the catchment scale.

Authors/Creators:Erlandsson Lampa, Martin and Sverdrup, Harald U. and Bishop, Kevin and Belyazid, Salim and Ameli, Ali and Köhler, Stephan
Title:Catchment export of base cations: improved mineral dissolution kinetics influence the role of water transit time
Year of publishing :2020
Volume:6
Page range:231-244
Number of Pages:14
Publisher:Copernicus Publications
ISSN:2199-3971
Language:English
Publication Type:Journal article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
URN:NBN:urn:nbn:se:slu:epsilon-p-106728
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-106728
Additional ID:
Type of IDID
DOI10.5194/soil-6-231-2020
Web of Science (WoS)000538410400002
ID Code:17275
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Aquatic Sciences and Assessment
Deposited By: SLUpub Connector
Deposited On:19 Aug 2020 11:48
Metadata Last Modified:19 Aug 2020 11:48

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