Stream Dissolved Organic Matter in Permafrost Regions Shows Surprising Compositional Similarities but Negative Priming and Nutrient Effects

Permafrost degradation is delivering bioavailable dissolved organic matter (DOM) and inorganic nutrients to surface water networks. While these permafrost subsidies represent a small portion of total fluvial DOM and nutrient fluxes, they could influence food webs and net ecosystem carbon balance via...

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Bibliographic Details
Published in:Global biogeochemical cycles 2021-01, Vol.35 (1), p.e2020GB006719-n/a
Main Authors: Wologo, Ethan, Shakil, Sarah, Zolkos, Scott, Textor, Sadie, Ewing, Stephanie, Klassen, Jane, Spencer, Robert G. M., Podgorski, David C., Tank, Suzanne E., Baker, Michelle A., O'Donnell, Jonathan A., Wickland, Kimberly P., Foks, Sydney S. W., Zarnetske, Jay P., Lee‐Cullin, Joseph, Liu, Futing, Yang, Yuanhe, Kortelainen, Pirkko, Kolehmainen, Jaana, Dean, Joshua F., Vonk, Jorien E., Holmes, Robert M., Pinay, Gilles, Powell, Michaela M., Howe, Jansen, Frei, Rebecca J., Bratsman, Samuel P., Abbott, Benjamin W.
Format: Article
Language:English
Subjects:
Acetates
Acetic acid
Aquatic ecosystems
Bioavailability
Biodegradability
Biodegradation
Biogeosciences
Carbon
Carbon Cycling
Colour
Creeks & streams
Cryobiology
Cryosphere
cryosphere and high‐latitude processes
Cyclotron resonance
Dissolved organic matter
Environmental conditions
Fluxes
Food chains
Food webs
Fourier analysis
Fourier transforms
High-altitude environments
Hydrology
Marine Organic Chemistry
Mass spectrometry
Mass spectroscopy
Mineral nutrients
Mineralization
Nutrient availability
Nutrient balance
Nutrient uptake
Nutrients
Nutrients and Nutrient Cycling
Oceanography: Biological and Chemical
Optical communication
Optical properties
Permafrost
Permafrost, Cryosphere, and High‐latitude Processes
Phosphorus
Priming
Receiving waters
Regions
Riparian Systems
River Channels
Rivers
Stoichiometry
Subsidies
Surface water
Thermokarst
Uptake
Waterways
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Summary:Permafrost degradation is delivering bioavailable dissolved organic matter (DOM) and inorganic nutrients to surface water networks. While these permafrost subsidies represent a small portion of total fluvial DOM and nutrient fluxes, they could influence food webs and net ecosystem carbon balance via priming or nutrient effects that destabilize background DOM. We investigated how addition of biolabile carbon (acetate) and inorganic nutrients (nitrogen and phosphorus) affected DOM decomposition with 28‐day incubations. We incubated late‐summer stream water from 23 locations nested in seven northern or high‐altitude regions in Asia, Europe, and North America. DOM loss ranged from 3% to 52%, showing a variety of longitudinal patterns within stream networks. DOM optical properties varied widely, but DOM showed compositional similarity based on Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR MS) analysis. Addition of acetate and nutrients decreased bulk DOM mineralization (i.e., negative priming), with more negative effects on biodegradable DOM but neutral or positive effects on stable DOM. Unexpectedly, acetate and nutrients triggered breakdown of colored DOM (CDOM), with median decreases of 1.6% in the control and 22% in the amended treatment. Additionally, the uptake of added acetate was strongly limited by nutrient availability across sites. These findings suggest that biolabile DOM and nutrients released from degrading permafrost may decrease background DOM mineralization but alter stoichiometry and light conditions in receiving waterbodies. We conclude that priming and nutrient effects are coupled in northern aquatic ecosystems and that quantifying two‐way interactions between DOM properties and environmental conditions could resolve conflicting observations about the drivers of DOM in permafrost zone waterways. Key Points Dissolved organic matter (DOM) from diverse circumpolar regions showed compositional and optical commonalities Added acetate and nutrients suppressed background DOM degradation but accelerated colored DOM breakdown Disconnect between DOM composition and function indicates intrinsic and extrinsic conditions interact to regulate DOM dynamics
ISSN:0886-6236
1944-9224
DOI:10.1029/2020GB006719