Integrating Terrestrial and Aquatic Carbon Export in a Headwater Catchment 5 views

Dissolved organic carbon (DOC) transport dynamics have been extensively studied in headwater catchments, but uncertainty persists around export at the event scale, particularly regarding source depletion. Currently missing from the literature is a study that considers both DOC export from soil to stream and mineralization through soil respiration. To address this gap, hourly lateral and vertical carbon fluxes were quantified for a full year at Paine Run in Shenandoah National Park in Virginia, USA, to determine if competition between these alternate carbon export pathways influences stream DOC fluxes. 38 days of soil respiration measurements taken with a portable chamber were used to calculate hourly respiration estimates from continuous soil temperature and moisture observations at a near stream and hillslope site. An in stream sensor measured hourly fluorescent dissolved organic matter (fDOM), which was used to calculate hourly DOC from a rating curve developed samples covering the full range of discharge. Annual mean soil respiration across 10 sample sites was 1160 g m-2, compared to a stream flux of 0.583 g m-2. The difference in magnitude between these fluxes indicates that respiration rates regulate the size of the soil DOC pool, suggesting that lateral flushing is unlikely to cause source limitation, and highlighting the role of heterotrophic respiration in regulating stream DOC concentrations.

MS (Master of Science)

English

2026-08-01