THE EFFECT OF SOURCE AREA AND ATMOSPHERIC TRANSPORT ON MINERAL AEROSOL COLLECTED OVER THE NORTH PACIFIC-OCEAN

Aerosol samples collected on two North Pacific cruises were analyzed f or rock-magnetic properties, grain size and < 2 mu m and 2-20 mu m min eralogy. These sedimentological results were compared with isentropic air mass trajectories in order to study the effects of source region a nd atmospheric transport on the mineral aerosol. The results indicate that there are differences in the aerosol composition and grain size f or two broad source regions. Aerosols which originate from west of the Pacific an characterized by abundant, fine-grained aerosol, which has a high coercivity magnetic composition, and is relatively enriched in kaolinite. Aerosols originating from continents to the north and east of the Pacific basin are much less abundant, contain coarse-grained m aterial with a low coercivity magnetic component, and the mineralogy i s relatively enriched in plagioclase. Comparison of the mineral aeroso l from Asia with atmospheric transport time indicated that the concent ration of the mineral aerosol decreases with increasing transport time . The mineral aerosol is compositionally fractionated as it moves away from the continental source region, with a relative decrease in the p rimary minerals quartz and plalagioclase and an increase in the smecti te, illite and chlorite concentration with increasing transport time. (C) 1998 Elsevier Science B.V. All rights reserved.