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Aerosol chemistry over remote oceanic regions


Johansen, Anne Marie Jorunn (1999) Aerosol chemistry over remote oceanic regions. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/P5HP-F516.


NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Atmospheric sampling of aerosol was carried out from ships during four separate month-long research cruises over remote oceanic regions. Three cruises took place in the Arabian Sea, during the inter-, SW- and NE-monsoons. An additional cruise was focused on the tropical North Atlantic Ocean. Identical sampling techniques were employed for all cruises. One high volume dichotomous virtual impactor and two low volume collectors were used to collect aerosol particles for the quantification of trace metals, anions and major cations. Ferrous iron concentrations were determined immediately after sample collection on board the ship using a ferrozine extraction technique. Data were analyzed by principal component, enrichment factor and weighted multiple linear regression analyses. The mineralogical composition of aerosol collected over the Arabian Sea reflected that of an average of the earth's crust, while over the Atlantic Ocean, shale appeared to best represent the sampled mineral dust. With exception of the SW-monsoon samples, which were characterized by weak continental influences, the aerosol samples contained excess water-soluble non-sea-salt calcium that appeared to be of crustal origin, in the form of CaCO[...] or CaSO[...]. Ferrous iron concentrations accounted for 0.3, 1.3, and 0.5% of the total observed Fe during the inter- and NE-monsoons over the Arabian Sea, and over the Atlantic Ocean, respectively. Absolute Fe(II) concentrations were determined at 5.2, 9.8, and 3.1 [...]g [...] for the corresponding seasons, with most of the Fe(II) (> 80%) present in the fine fraction. Fe(II) did not exhibit a simple relationship with any of the sources indicating the complexity of iron redox reactions is this system. Non-sea-salt sulfate (NSS-SO[...]) sources were identified and quantified with the use of multiple linear regression analyses. Biogenically-derived [...] contributed significant amounts of NSS-SO42-, especially during the SW-monsoon, when anthropogenic sources were small. Biogenic SO[...]/methansulfonic acid (MSA) weight ratios were determined and found to be in agreement with reported literature values from pristine oceanic regions, varying from 6.8 at 24°C to 17.7 at 28.9°C.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Environmental Science and Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Hoffmann, Michael R.
Thesis Committee:
  • Hoffmann, Michael R. (chair)
  • Cass, Glen Rowan
  • Morgan, James J.
  • Hering, Janet G.
Defense Date:28 April 1999
Record Number:CaltechETD:etd-02272008-111006
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:787
Deposited By: Imported from ETD-db
Deposited On:12 Mar 2008
Last Modified:21 Dec 2019 04:16

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PDF (Johansen_amj_1999.pdf) - Final Version
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