title: Inland waters and their role in the carbon cycle of Alaska.
abstract: The magnitude of Alaska (AK) inland waters carbon (C) fluxes is likely to change in the future due to amplified climate warming impacts on the hydrology and biogeochemical processes in high latitude regions. Although current estimates of major aquatic C fluxes represent an essential baseline against which future change can be compared, a comprehensive assessment for AK has not yet been completed. To address this gap, we combined available data sets and applied consistent methodologies to estimate river lateral C export to the coast, river and lake carbon dioxide (CO2) and methane (CH4) emissions, and C burial in lakes for the six major hydrologic regions in the state. Estimated total aquatic C flux for AK was 41 Tg C/yr. Major components of this total flux, in Tg C/yr, were 18 for river lateral export, 17 for river CO2emissions, and 8 for lake CO2emissions. Lake C burial offset these fluxes by 2 Tg C/yr. River and lake CH4emissions were 0.03 and 0.10 Tg C/yr, respectively. The Southeast and South central regions had the highest temperature, precipitation, terrestrial net primary productivity (NPP), and C yields (fluxes normalized to land area) were 77 and 42 g C·m-2·yr-1, respectively. Lake CO2emissions represented over half of the total aquatic flux from the Southwest (37 g C·m-2·yr-1). The North Slope, Northwest, and Yukon regions had lesser yields (11, 15, and 17 g C·m2·yr-1), but these estimates may be the most vulnerable to future climate change, because of the heightened sensitivity of arctic and boreal ecosystems to intensified warming. Total aquatic C yield for AK was 27 g C·m-2·yr-1, which represented 16% of the estimated terrestrial NPP. Freshwater ecosystems represent a significant conduit for C loss, and a more comprehensive view of land-water-atmosphere interactions is necessary to predict future climate change impacts on the Alaskan ecosystem C balance.
authors.affiliation: U.S. Geological Survey, National Research Program, Denver Federal Center, MS413, Denver, Colorado, 80225, USA.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Stackpoole
authors.affiliation: National Research Program, U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado, 80303, USA.|School of Environmental and Forest Sciences and Civil & Environmental Engineering, University of Washington - Seattle, Box 325100, Seattle, Washington, 98195, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Butman
authors.affiliation: U.S. Geological Survey, Colorado Water Science Center, Denver Federal Center, MS415, Denver, Colorado, 80225, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Clow
authors.affiliation: U.S. Geological Survey, Colorado Water Science Center, Denver Federal Center, MS415, Denver, Colorado, 80225, USA.
authors.forename: Kristine L
authors.initials: KL
authors.lastname: Verdin
authors.affiliation: U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, Alaska, 99508, USA.|Tree Ring Lab, Lamont-Doherty Earth Observatory, 61 Route 9W - PO Box 1000, Palisades, New York, 10964, USA.
authors.forename: Benjamin V
authors.initials: BV
authors.lastname: Gaglioti
authors.affiliation: Institute of Arctic Biology, University of Alaska - Fairbanks, 902 Koyukuk Drive, Fairbanks, Alaska, 99775, USA.
authors.forename: Hélène
authors.initials: H
authors.lastname: Genet
authors.affiliation: National Research Program, U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado, 80303, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Striegl
mesh_terms: D000413:Alaska; D057486:Carbon Cycle; D000074382:Greenhouse Gases / Q000032:analysis; D060106:Lakes / Q000737:chemistry*; D008697:Methane / Q000032:analysis; D045483:Rivers / Q000737:chemistry*
chemical_list: D000074382:Greenhouse Gases; D008697:Methane
keywords: Alaska carbon cycle; Arctic; boreal; carbon balance; coastal rainforest; glacier; greenhouse gas emissions; inland waters; lateral export; methane; permafrost; yedoma