Iron mobilization in mineral dust: Can anthropogenic SO2 emissions affect ocean productivity?

For Fe contained in long-range transported aeolian dust to act as a micronutrient for oceanic phytoplankton it must be first dissolved or mobilized. We propose that Fe-mobilization 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.