HR: 1340h
AN: OS43A-0988    [Abstracts]
TI: Spatial Variability of Land-Sea Carbon Exchange at a Coastal Area in Barrow, Alaska
AU: * Ikawa, H
EM: hikawa@sunstroke.sdsu.edu
AF: San Diego State University, 5500 Campanile Dr., San Diego, CA 92182-4614, United States
AU: Oechel, W
EM: oechel@sunstroke.sdsu.edu
AF: San Diego State University, 5500 Campanile Dr., San Diego, CA 92182-4614, United States
AU: Hastings, S
EM: shastings@sunstroke.sdsu.edu
AF: San Diego State University, 5500 Campanile Dr., San Diego, CA 92182-4614, United States
AB: Relatively cold and low salinity sea water of the Arctic Ocean was considered to be a sink for atmospheric CO2 (Takahashi et al., 1997) because the solubility of CO2 in seawater increases as temperature decreases, and the arctic sea water transports CO2 to greater depths. However, carbon exchange in the Arctic sea is not well evaluated yet, because available data is very limited (Semiletov et al., 2007). Also, terrestrial inflows, such as thawing permafrost and coastal erosion, also affect oceanic air-sea CO2 exchange especially in the Arctic (ACIA., 2004) creating a variety of regional carbon cycles (Semiletov et al., 2007). Our aim is to quantify an air-sea CO2 exchange of a spatially wide coastal sea area, in Barrow, Alaska and to extrapolate the future carbon cycle in response to climate change. Boat cruises for pCO2 measurements operated from July 29 to August 5, 2007. The surveyed area was mainly divided into three parts: Chukchi Sea, Beaufort Sea, and Elson Lagoon. Conductivity of sea surface (CS) and sea surface temperature (SST) were also measured together with pCO2. The result showed distinct differences in pCO2 among three areas. Average delta pCO2 (dpCO2) (a difference between an atmospheric CO2 and pCO2), CS, and SST were -114.9 ppm, 47.0 mScm-1, and 8.0 C at Chukchi Sea, -53.1 ppm, 43.5 mScm-1, and 8.9 C at Beaufort Sea, and 43.7 ppm, 41.1 mScm-1, and 9.5 C at Elson Lagoon. Relatively high dpCO2 value in the Beaufort Sea implies a large terrestrial input from Elson Lagoon where dpCO2 value is positive. This is supported by lower CS in the Beaufort Sea and Elson Laggon than in the Chukchi Sea. Sea currents from Pacific Ocean, which continuously flow through the Chukchi Sea, are thought to carry warmer water. However, SST was lower in the Chukchi Sea than in the Beaufort Sea. This may be because a prevailing wind from north east creates Ekman transport causing an upwelling along the Chukchi Sea coast and this upwelling carries deep cold water to the surface (personal communication with Dr.Okkonen of UAF). pCO2 is very sensitive to temperature and total carbon material in the water. A simple temperature-pCO2 equation suggested by Takahashi (Takahashi et al., 1993) showed an air-sea CO2 exchange in Beaufort Sea could be reversed from a sink to a source if SST increases by 3.7 C under a constant chemical condition. Moreover, pCO2 is very sensitive to a total carbon matter in water because of the high Revelle factor. Ongoing thawing of the permafrost and increasing coastal erosion (Aguirre et al., 2006) changes not only terrestrial carbon cycle (Oechel et al., 1994) but also oceanic carbon cycle as well in the Arctic.
DE: 4806 Carbon cycling (0428)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting