Carbon dioxide partial pressures in arctic surface waters1

Abstract

Seasonal changes in the CO₂ partial pressure (PCO₂) regime for an arctic freshwater pond and lake near Barrow, Alaska, were measured by infrared gas analysis by determining the CO₂ concentration of air in equilibrium with the water. These waters were generally supersaturated in CO₂ with respect to air throughout the period of open water and constitute a CO₂ source to the arctic atmosphere. Meltwater standing on the bottomfast ice of the lake in spring and water beneath the newly formed ice in fall also had CO₂ partial pressures greater than ambient air. The seasonal mean CO₂ partial pressure gradient between the water and the ambient air was 397±185 ppm for the pond and 115±83 ppm for the lake. PCO₂ was inversely related to wind speed and water temperature but directly related to sediment temperature. Evasion rate coefficients calculated for the lake, based on in situ rate experiments, indicated an average transfer of 0.34±0.17 mg CO₂ cm⁻² atm⁻¹ min⁻¹ to the atmosphere.