HR: 1340h
AN: PP23B-1435    [Abstracts]
TI: Accessing Silver as a Paleoceanographic Proxy
AU: * Kramer, D
EM: dkramer@uvic.ca
AF: University of Victoria, School of Earth and Ocean Sciences, Victoria, BC V8W 3P6 Canada
AU: Pedersen, T F
EM: tfp@uvic.ca
AF: University of Victoria, School of Earth and Ocean Sciences, Victoria, BC V8W 3P6 Canada
AB: A strong correlation has been found between dissolved silver and silicic acid at several locations in the sea, especially in the Pacific. This has led to the hypothesis that diatom opal acts as a vector of silver to the sea floor. If so, and if silver released by dissolution is sequestered by the sediments, it is possible that downcore sedimentary silver concentrations could be used as a paleo-proxy for the diatom settling flux. However, recent studies have found that the Ag:H4SiO4 correlation is weak in some areas and a more detailed examination of the Ag:Si relationship is needed before any paleo-inferences can be made from sedimentary silver concentrations. Toward this end, a 13 month time series study has begun in Saanich Inlet, BC, Canada, focusing on silver and silicate levels in sediment trap materials, water column samples and the underlying sediments. Initial results show that silicate levels were reduced by up to 80% in the upper 80 m of the water column during the spring bloom. It is expected that silver levels will show a similar depletion. The results of dissolved and particulate silver analyses now underway will be presented at the meeting, in conjunction with a suite of supporting data (sediment-trap opal, organic carbon and nitrogen contents, and dissolved nutrient measurements). The anticipated results and their interpretation should contribute to the potential calibration of the sedimentary Ag content as a paleotracer of diatom production.
DE: 4805 Biogeochemical cycles (1615)
DE: 4267 Paleoceanography
DE: 1050 Marine geochemistry (4835, 4850)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting