Modelling multiseasonal preferential transport of dissolved organic carbon in a shallow forest soil: Equilibrium versus kinetic sorption. Issue 22 (28th August 2019)

• Record Type: Journal Article
• Authors: Dusek, Jaromir; Dohnal, Michal; Vogel, Tomas; Marx, Anne; Barth, Johannes A.C.
• Is Part Of: Hydrological processes. Volume 33:Issue 22(2019)
• Page Start: 2898
• Page End: 2917
• Publication Date: 2019-08-28
• Subjects: dissolved organic carbon -- DOC adsorption/desorption -- dual‐permeability model -- hillslope discharge -- kinetic sorption -- Monte Carlo analysis -- preferential transport -- uncertainty; Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.13536
• Languages: English
• ISSNs: 0885-6087

Abstract

Abstract: Parameterization of transformation and transport processes of dissolved organic carbon (DOC) in soils is challenging especially under variable hydrological conditions. In this study, DOC concentrations in stormflow were analysed with a physically based modelling approach. A one‐dimensional dual‐continuum vertical flow and transport model was applied to simulate subsurface processes in a macroporous forest hillslope soil over a period of 4.5 years. Microbially mediated transformations of DOC were assumed to depend primarily on soil moisture and soil temperature. Two conceptually different descriptions of the sorption of DOC to soil were examined with equilibrium and kinetic approaches. In order to quantify the uncertainties associated with the model parameterization, Monte Carlo analyses in conjunction with Latin hypercube sampling was performed. Despite the complexity of microbial transformations, the simulated temporal patterns of DOC concentrations in stormflow showed similar behaviour to those reflected in the observed DOC fluxes. Due to preferential flow, the hillslope DOC export (5.0 ± 0.5 g C · m −2 · year −1 ) was higher than the amounts usually reported in the literature. Overall DOC transport in hillslope scenarios could be described appropriately using the equilibrium sorption assumption. The performed analyses showed that the inclusion of the kinetic description of DOC sorption only slightly improved the predictions of the DOC hillslope export. Moreover, influences of seasonal hydro‐climatological conditions on hillslope export of DOC could be observed. Reduced DOC transport during an extreme warm and dry summer was described with lower accuracy, thus indicating the difficulties in the representation of DOC transformations under dry conditions. Abstract : A physically based one‐dimensional flow and transport model was used to analyze the long‐term transport of dissolved organic carbon (DOC) in a hillslope. Both intraannual and interannual variability of DOC hillslope export, influenced by hydrological and atmospheric conditions, was significant. The variations of DOC mass fluxes in stormflow were reasonably well described using both equilibrium and kinetic sorption model.