Arctic Lakes and Streams as Gas Conduits to the Atmosphere: Implications for Tundra Carbon Budgets

Abstract

Arctic tundra has large amounts of stored carbon and is thought to be a sink for atmospheric carbon dioxide (CO₂) (0.1 to 0.3 petagram of carbon per year) (1 petagram = 10¹⁵ grams). But this estimate of carbon balance is only for terrestrial ecosystems. Measurements of the partial pressure of CO₂ in 29 aquatic ecosystems across arctic Alaska showed that in most cases (27 of 29) CO₂ was released to the atmosphere. This CO₂ probably originates in terrestrial environments; erosion of particulate carbon plus ground-water transport of dissolved carbon from tundra contribute to the CO₂ flux from surface waters to the atmosphere. If this mechanism is typical of that of other tundra areas, then current estimates of the arctic terrestrial sink for atmospheric CO₂ may be 20 percent too high.