Ground Ice Variations Among Soil Horizons and Ice-Wedge Polygon Types in Arctic Coastal Lowland Soils
Authors
Julie Jastrow1* (jdjastrow@anl.gov), Roser Matamala1, Chien-Lu Ping2, Gary Michaelson2, Timothy Vugteveen1, Jeremy Lederhouse1, Joshua Minai1
Institutions
1Argonne National Laboratory, Lemont, IL; 2University of Alaska–Fairbanks, AK
URLs
Abstract
In Arctic coastal lowlands dominated by ice-wedge polygons (IWPs), a better understanding of near-surface ground ice quantities and their spatial distribution is needed to improve model predictions of ecosystem and landscape responses to climatic change. In investigations of how IWP geomorphology (trough vs. center), size, and types (i.e., flat-, low-, and high-centered IWPs) affect the distribution and composition of soil organic carbon (SOC) stocks, the team also collected considerable ground ice data. These data estimate the spatial distribution of volumetric ice contents to depths of up to 3 meters within the cross-section stratigraphy of soil horizons and ice wedges for transects running from trough center to trough center of sampled IWPs. Data from nine IWPs (three of each type) located in the thaw-lake terrain near Utqiaġvik, AK, indicate that the greatest volumetric ice contents occurred, on average, at depths between 0.45 m and 1 m in the upper permafrost of high-centered IWPs, due mostly to proportionately larger areas occupied by the ice wedges. Averaged across all IWP types, organic and mixed organic/mineral horizons generally had greater volumetric ice contents than mineral horizons. Not surprisingly, the team found a strong negative relationship between ice content and soil bulk density due to the frequent occurrence of excess ice. However, the team also observed a positive relationship between ice content and SOC density (kg C m-3). Future work will compare the ground ice contents observed near Utqiaġvik and their relationships with IWP type, soil horizon type, and SOC density to that of polygonal landscapes formed on other soil parent materials.