HR: 17:15h
AN: OS44B-06    [Abstracts]
TI: Effects of an Asian Dust Storm on the Gulf of Alaska: Trace Metal Evidence and Biological Consequences
AU: * Crispo, S M
EM: scrispo@chem.ubc.ca
AF: Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1 Canada
AU: Peterson, T D
EM: tdpeters@eos.ubc.ca
AF: Department of Oceanography, University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AU: Lohan, M C
EM: mlohan@es.ucsc.edu
AF: Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, CA 95064 United States
AU: Crawford, D
EM: dwcr@soc.soton.ac.uk
AF: School of Ocean and Earth Sciences, University of Southampton, Southampton Oceanography Centre, Southampton, SO14 3ZH United Kingdom
AU: Orians, K J
EM: korians@eos.ubc.ca
AF: Department of Oceanography, University of British Columbia, Vancouver, BC V6T 1Z4 Canada
AU: Harrison, P J
EM: harrison@ust.hk
AF: Atmospheric, Marine & Coastal Environment (AMCE) Program, The Hong Kong University of Science & Technology HKUST, Kowloon, n/a Hong Kong
AU: Statham, P J
EM: pjs1@soc.soton.ac.uk
AF: School of Ocean and Earth Sciences, University of Southampton, Southampton Oceanography Centre, Southampton, SO14 3ZH United Kingdom
AB: In April 2001, a large dust storm originating in the Gobi and Takla Makan deserts resulted in large quantities of dust to be transported to the northeastern Pacific Ocean. Off the California coast, dissolved iron and aluminum concentrations determined before and after the dust traversed the North Pacific show increases of 0.5nM and 2nM respectively (Johnson, 2003). The most concentrated plume of dust traveled toward the eastern Gulf of Alaska. Every year anticyclonic mesoscale eddies, transporting coastal waters offshore, form off the coast of the Queen Charlotte Islands, British Columbia. These Haida eddies begin with high concentrations of trace metals which deplete over time. Evidence of 2001-dust deposition is seen in elevated dissolved aluminum concentrations (up to 7nM) in the eddy, which stay elevated months after the dust was deposited. By June 2001, dissolved zinc concentrations in the eddy surface mixed layer are low (below 0.3nM) and decrease slightly by September 2001. Dissolved cadmium concentrations dropped drastically (from 0.4nM to 0.09nM) from June to September 2001 in the Haida-2001 eddy coinciding with a large increase in coccolithophore production. This coccolithophore increase was five times greater than what was seen in the Haida-2000 eddy and twenty times that of the reference station. Based on our observations and by comparison with a shipboard Zn-Fe-enrichment study, we hypothesize that dust deposition into surface waters promotes growth first of diatoms and then of coccolithophores once zinc is depleted. The presence of dust remnants held within a quasi-isolated mesoscale eddy allows us to draw conclusions about succession following dust deposition events and yields further information regarding interactions between trace metal supply and primary production in the NE Subarctic Pacific.
DE: 4825 Geochemistry
DE: 4855 Plankton
DE: 4870 Stable isotopes
DE: 4520 Eddies and mesoscale processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting