Modeling the dissolved organic carbon output from a boreal mire using the convection‐dispersion equation: Importance of representing sorption

Abstract

[1] In this paper we present a model of the dissolved organic carbon (DOC) concentrations and fluxes in mire water based on the convection-dispersion equation. The dynamics of sorbed, potentially soluble organic carbon (SPSOC) in the peat matrix are simulated in parallel with DOC. First, the model is applied solely to stagnant water conditions in order to interpret the results of laboratory peat incubations, with the focus on sorption processes. Some important model parameters are derived using literature data complemented by information from new incubation experiments. Second, the model is fully applied to simulate the DOC concentrations in the outlet of a steam draining a small headwater mire in northern Sweden during the period 1993-2001. A relatively good model fit (mean bias error (MBE) = À0.6-2.2 mg L À1 , Willmott index of agreement d > 0.7 for the daily concentrations) was found for all the categories of stream discharge, except periods with very low flow (q < 0.3 mm d À1 ). When seeking explanations for the interannual variability in DOC concentrations, we, like previous authors, could find the influence of temperature, flow path, and intensity. However, the model has helped to demonstrate that the system also has a ''memory'': the store of sorbed, potentially soluble organic carbon in a year affects the DOC concentrations and fluxes in the following year.

Long-term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments: trends, mechanisms and heterogeneity

“…The C4 dilution can be attributed to less water infiltrating and subsequent reduced contact time with peat Yurova et al, 2008). Similar autumn dilution pattern in C7 (Köhler et al, 2008) can be attributed to the influence of the upstream mire during the autumn season.…”

“…Vegetation in the mires mainly consists of Sphagnum sp. (Yurova et al, 2008). The region has a long-term mean air temperature of with the highest temperatures occurring in July.…”

“…The objectives of this study were (1) to evaluate the temporal pattern of long-term and seasonal trends in stream chemical parameters and surface water [DOC] Köhler et al, 2008;Winterdahl et al, 2011a;Yurova et al, 2008) but none has examined the entire 25+ yr record for some parameters and their possible linkages with DOC dynamics. It is our expectation that this study will contribute to the understanding of the dominant biogeochemical mechanisms and lead to improved process-modelling efforts in pristine boreal headwater catchments in the future.…”

Cross-scale ensemble projections of dissolved organic carbon dynamics in boreal forest streams

“…The strength of the model proposed by Lumsdon et al (2005) is its focus on organic carbon solubility in the soil. The Mire DOC model proposed by Yurova et al (2008), works well for peaty wetlands, but might not be able to give a credible representation of the contrasting mechanisms controlling DOC in forest streams. The wide variation in process understanding, conceptualization and representation in these DOC models could lead to large uncertainties that could potentially be of the same order of magnitude as the uncertainty associated with future climate projections or even larger.…”

Simulating Dissolved Organic Carbon Dynamics at the Swedish Integrated Monitoring Sites with the Integrated Catchments Model for Carbon, INCA-C

“…SMR of time-lagged climate and deposition parameters has shown that changes in acidic deposition can explain substantial proportions of long-term trends in surface water [DOC] in a series of Norwegian catchments Futter and de Wit 2008). End-member mixing analysis has been applied to simulate streamwater [DOC] as a function of inputs from catchment soils and wetlands (Easthouse et al 1992), and a physically based model of DOC production and transport in boreal mires has been presented (Yurova et al 2007). Detailed chemical modeling can also help to elucidate effects of soil water variables on surface water [DOC] (Löfgren et al 2010b).…”