ARCTIC LAKES AND STREAMS AS GAS CONDUITS TO THE ATMOSPHERE - IMPLICATIONS FOR TUNDRA CARBON BUDGETS

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 = 10(15) 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.