Evaluating the effects of non-perennial streamflow regimes on dissolved organic matter composition and bioavailability using high-resolution mass spectrometry
EMSL Project ID
61094
Abstract
Climate change and land development are increasing the prevalence of non-perennial streams across much of the continental US. Non-perennial streams exhibit dynamic flow conditions that can fluctuate rapidly between dry and high flow states, stimulating biogeochemical organic matter (OM) transformations and regulating carbon cycling and export into downstream ecosystems. The goal of this research is to evaluate how variable saturation patterns impact the molecular composition of dissolved organic matter (DOM) in non-perennial headwater streams. We aim to apply Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) to characterize the complexity and diversity of DOM isolated from surface sediments in three distinct hydrologic zones of a non-perennial stream channel. We predict that different saturation regimes due to the extent of streamflow intermittency will drive redox reactions that control the processing and bioavailability of DOM components. Specifically, we hypothesize that (H1) extended dry periods will increase subsurface oxygenation and promote the microbial oxidation of OM and release as CO2, increasing the amount of reduced and condensed-aromatic DOM components; (H2) highly-unsaturated and aliphatic DOM components will accumulate in persistently inundated areas due to limited subsurface oxygenation inhibiting OM biotransformation; (H3) repeated wet-dry cycles will increase DOM chemodiversity by alternating between high rates of subsurface OM biotransformation during dry periods and fresh inputs of terrestrial OM when flow resumes. This proposal targets the collection of supplementary data to work performed under the Watershed Dynamics and Evolution Science Focus Area (WaDE SFA) at Oak Ridge National Laboratory and is intended to support a larger EMSL user facility proposal.
Project Details
Project type
Limited Scope
Start Date
2024-03-18
End Date
N/A
Status
Accepted
Released Data Link
Team
Principal Investigator
Co-Investigator(s)