Document: AND-3-59-82

Carbon dioxide flux in Antarctic Dry Valley soils.

PARSONS, A.N* ¹, J.EBARRETT ², R.AVIRGINIA ² and D.HWALL ¹

Colorado State University, Fort Collins, CO 80523, USA ¹
Dartmouth College, Hanover, NH, USA ²

Abstract:
The Dry Valleys of Antarctica are one of the most extreme desert environments on earth. The sources of legacy organic matter in Dry Valley soils have been characterized recently, but the contribution of carbon from contemporary soil biological activity has been less studied, and little is known about the current rates of carbon cycling. We are investigating the biological, physical and chemical processes that contribute to CO₂ flux in dry valley soils. We established field plots in Lake Fryxell and Lake Hoare basins in Taylor Valley, (site of the McMurdo Long-term Ecological Research project) and took repeated measurements of soil CO₂ flux with a LiCor 6400 infra red gas analyzer modified to measure small rates of CO₂ flux. In a laboratory experiment we examined the role of temperature on flux rates by incubating soils in controlled conditions. In the field, maximum CO₂ flux rates (~0.2 mol m^-2 s^-1) were low compared to all other ecosystems and negative fluxes were observed. Maximum positive flux in the field experiment was recorded at soil temperatures above 5C. At the lowest soil temperatures (-2C), both positive and negative fluxes were recorded. Presently, the laboratory results indicate that increasing solubility of CO₂ in soil water may contribute to low or negative fluxes at low temperatures. We present a conceptual model that examines the relationship between the biological and geochemical controls over CO₂ flux in Antarctic soils.

Keywords: Antarctica, CO₂ flux, soil respiration, McMurdo LTER

This abstract is being presented at: 8:30 AM in session:
Oral Session #25: Organic Matter Dynamics in Ecosystems.