| dc.description.abstract | Arctic warming is causing increased export of sediments and organic matter via active
layer deepening and thermokarst slumps. A mechanistic numerical model was developed
using the ReacTran R package to predict riverine dissolved organic carbon (DOC) and total
suspended sediment (TSS) concentrations measured during a 2019 field expedition in the
Peel River watershed, YT, Canada. In addition to advective transport, two geochemical
DOC removal processes were implemented (DOC mineralization and adsorption to mineral
surfaces). The power of upstream slump affected area to predict riverine DOC and TSS
concentrations was also investigated via a random forest classifier used to identify slump
features in the landscape. However, other landscape properties (NDVI, NDMI) proved
to be better predictors of riverine DOC and TSS, possibly due to inaccuracies in the
classification. Steady state model results indicate that 70–90 % of total DOC input to the
river was exported from the downstream boundary unaffected by removal processes, and
the 10–30 % of input DOC that was removed was done so predominantly via adsorption
to mineral surfaces. Adsorption was driven by high TSS tributaries entering the model
domain in its downstream reaches, with the high TSS values possibly due to increased
slumping activity in the watersheds of these tributaries. Requisite sensitivity analyses were
not performed and offer opportunities for continuation of this work, as does expanding
the model to include dynamic inputs and splitting the bulk DOM pool into contributing
components. | |
