Landscape and Storm Characteristics Influence DOC and Nitrate Mobility and Riverine Export Magnitude in Two Arctic Catchments
Rec AF, Shogren AJ, Zarnetske JP, O'Donnell J, Grose AL, Abbott BW, Bowden WB. Landscape and Storm Characteristics Influence DOC and Nitrate Mobility and Riverine Export Magnitude in Two Arctic Catchments
Intensifying Arctic hydrological cycles and permafrost thaw alter the magnitude and timing of lateral solute fluxes to rivers, yet interactions among hydrological, biogeochemical, and landscape controls on carbon and nutrient export remain unclear. We calculated yields of dissolved organic carbon (DOC) and nitrate (NO3−) and storm hysteresis (HI) and flushing indices (FI) across six thaw seasons of high-frequency monitoring to examine solute export dynamics across timescales (daily, storm-event, monthly, annual) and flow conditions in two headwater catchments (River-dominated tundra vs. Lake-influenced tundra). High-flow conditions comprising less than 40% of the study period dominated annual thaw-season solute yields in both catchments, accounting for 75%–80% of annual thaw-season DOC and 55%–65% of NO3− yields. Storm-events reflected abundant DOC sources (+FI) and limited NO3− supply (−FI) in catchment soils. In the River-dominated catchment, storm HI and solute yields were related to storm intensity (as storm rising limb duration and peak storm discharge), while responses in the Lake-influenced catchment were more variable. Flow-weighted concentrations at daily and monthly timescales revealed patterns not detectable during individual storms, including a late-season increase in DOC in the Lake-influenced catchment that may indicate a seasonal shift in DOC source. Overall, our analysis suggests that catchment storage components such as in-network lakes introduce variability in solute export behaviors and may decouple concentration-discharge relationships at high flows. This study provides a mechanistic framework to connect disparate temporal scales of hydrochemical observation and offers a clearer understanding of catchment-specific processes that regulate the timing and magnitude of solute export in Arctic headwaters.
- Type
- Journal Article
- Authors
- Rec, Abigail; Shogren, Arial; Zarnetske, Jay; O'Donnell, Jonathan; Grose, Amelia; Abbott, Benjamin; Bowden, William