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Abstract The heterogeneity of carbon dioxide (CO2) and methane (CH4) sources within and across watersheds presents a challenge to understanding the contributions of different ecosystem patch types to stream corridor and watershed carbon cycling. Changing hydrologic connections between corridor patches (e.g., streams, vernal pools, hillslopes) can influence stream corridor greenhouse gas emissions, but the spatiotemporal dynamics of emissions within and among corridor patches are not well‐quantified. To identify patterns and sources of carbon emissions across stream corridors, we measured gas concentrations and fluxes over two summers at Coweeta Hydrologic Laboratory, NC. We sampled CO2and CH4along four stream channels (including flowing and dry reaches), adjacent vernal pools, and riparian hillslopes. Stream CO2and CH4emissions were spatially heterogeneous. All streams were sources of CO2to the atmosphere (median = 97.2 mmol m−2d−1) but were sources or sinks of CH4depending on location (−0.19 to 4.57 mmol m−2d−1). CO2emissions were lower during the drier of two sampling years but were stable from month to month in the drier summer. CO2and CH4emissions also varied by both corridor and patch type; the presence of a vernal pool in the corridor had the strongest impact on emissions. Vernal pool patches emitted more CO2and CH4(246 and 1.95 mmol m−2d−1, respectively) than their adjacent streams. High resolution sampling of carbon fluxes from patches within and among stream corridors improves our understanding of the connections between terrestrial, riparian, and aquatic zones in a watershed and their contributions to overall catchment carbon emissions.
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This content will become publicly available on May 1, 2026
CO 2 Emissions From Low Order Tundra Streams Stimulated by Surface‐Subsurface Connectivity Following Extreme Rainfall Events
Abstract Increases to summer Arctic rainfall and tundra thermal degradation are altering hydrological cycling in coastal watersheds with implications for carbon (C) cycling and transport of C to the atmosphere and coast. Arctic riverine research has focused on large rivers; however, small streams contribute significantly to vertical and longitudinal carbon dioxide (CO2) fluxes. Despite the well‐established connection between hydrology and biogeochemistry, the impact of extreme rainfall events on Arctic aquatic C cycling remains a knowledge gap. This study characterized how hydrology, biogeochemistry, and geomorphology control the supply of CO2to low order streams and their propensity to act as atmospheric CO2sources. We characterize biogeochemical and hydrologic processes in unique reaches from a beaded stream and stream impacted by thermal erosion. Rainfall and its resulting increases to terrestrial‐aquatic connectivity drove the movement of CO2and biodegradable dissolved organic C (BDOC) from soils into streams, however, BDOC mineralization only contributed a small portion of surface CO2fluxes. Rain events likely stimulated stream benthic respiration, which led to CO2contributions from net ecosystem production often exceeding surface CO2fluxes and downstream CO2transport. In addition, thermal degradation played a role in terrestrial‐aquatic connectivity of the streams. The erosion‐affected stream had inconsistent and smaller inputs of CO2, had weaker heterotrophic conditions, and smaller CO2emissions. Understanding how hydrologic regime, influenced by late summer rain events and stream morphology, controls the transport of CO2and metabolism in small tundra streams will help improve predictions of landscape scale CO2emissions from these critically understudied systems.
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- Award ID(s):
- 2322664
- PAR ID:
- 10617665
- Publisher / Repository:
- Journal of Geophysical Research - Biogeosciences
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Biogeosciences
- Volume:
- 130
- Issue:
- 5
- ISSN:
- 2169-8953
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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