Abstract

For Fe contained in long-range transported acolian dust to act as a micronutrient for oceanic phytoplankton it must be first dissolved or mobilized. We propose that Femobilization can occur in mineral dust from East Asia by the incorporation of SO2 into the advecting dust plumes and subsequent acidification of the dust through heterogeneous SO2 oxidation. To test this hypothesis, we consider a dust plume that originated from the gobi-deserts and advected over the Pacific Ocean. Data collected over the Yellow Sea confirm that this plume contained high concentrations of dust and SO2. Significant gaseous HNO3 concentrations indicate that the dust particles were acidified (i.e., pH < 2). At these pH's, 1-2% of the Fe contained in a deliquescent mineral dust particle would be mobilized within 3-5 days. These results suggest a possible link between the rate of C-fixation in so-called High-Nitrate-Low-Chlorophyll regions of the Pacific Ocean and SO2 emissions from East Asia. Copyright 2003 by the American Geophysical Union.

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