HR: 13:40h
AN: PP43E-01 INVITED    [Abstracts]
TI: Controls on the Time Scale of Carbonate Neutralization of Carbon Dioxide Released to the Atmosphere
AU: * Caldeira, K
EM: kcaldeira@stanford.edu
AF: Dept of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, CA 94305, United States
AU: Cao, L
EM: longcao@stanford.edu
AF: Dept of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, CA 94305, United States
AB: Once released to the atmosphere, carbon dioxide is removed on a range of time scales. On the time scale of years to centuries, carbon dioxide removal from the atmosphere is dominated by transport processes within the ocean. On the time scale of hundreds of thousands of years, carbon dioxide removal from the atmosphere is dominated by processes related to the weathering of silicate rocks on land. Between these time scales, carbon dioxide removal is dominated by interactions involving carbonate minerals both on land and in the sea. Net dissolution of carbonate minerals (on land or in the sea) increases ocean alkalinity to an extent that exceeds the amount of carbon addition; the result is a transfer of carbon from the atmosphere to the ocean and moderation of the effects of added carbon on ocean chemical parameters such as pH and carbonate mineral saturation. There has been some controversy over how fast equilibration with carbonate minerals can neutralize carbon acidity, with claims ranging from the extreme and untenable claim that this process is essentially instantaneous to more plausible claims that the equilibration time scale may approach 10 kyr. Even within the domain of informed discourse, estimates of the carbonate neutralization timescale can vary by an order-of-magnitude. Here, in an effort to understand the sources of the lack of consensus on this issue, we examine how various processes (e.g., ocean transport, sediment pore water diffusion, carbonate-mineral dissolution, and carbonate weathering on land) influence the time scale for carbonate neutralization of carbon dioxide releases to the atmosphere.
DE: 0428 Carbon cycling (4806)
DE: 1051 Sedimentary geochemistry
DE: 1620 Climate dynamics (0429, 3309)
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
DE: 4825 Geochemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting