Biogeochemical Effects of Permafrost Degradation Across Alaska From Prudhoe Bay to Valdez

Document Type

Conference Paper

Publisher

American Geophysical Union

Publication Date

12-11-2023

Keywords

arctic permafrost, carbon, permafrost degradation, runoff

Abstract

Arctic permafrost is a significant reservoir of ancient terrestrial carbon. Understanding how and when permafrost carbon will be released is key for understanding the global terrestrial carbon sink. Permafrost is relatively impermeable, confining runoff to upper organic soil horizons and reducing transmission through deeper mineral soils. This limits the dissolution and transport of dissolved inorganic ions. Consequently, the downward migration of the active layer (i.e., permafrost degradation) could fundamentally alter the carbon and nutrient sources and their transport through permafrost surface waters. Here, we sampled stream water at more than 100 sites along a north-south transect across the entire state of Alaska, from Prudhoe Bay to Valdez, and throughout Unalaska in the Aleutian Islands. Sampling occurred at the end of the flow season when the thaw depth of the active layer was at its maximum. The sites spanned landscape characteristics, including permafrost zones characterizing the Arctic Tundra and Boreal Forest biomes. Water samples were analyzed for water stable isotopes, nutrients, and optical properties of dissolved organic matter. We tested how these water chemistry parameters were related to interacting state factors and modern changes, including watershed size, slope, aspect, surficial geology, glaciation history, land-atmosphere climate interactions, vegetation growth, wildfire disturbance, and urban development. We discuss how this unique data set can assess how carbon fluxes across the Arctic landscape may evolve under future permafrost conditions.

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