Iron mobilization in mineral dust: Can anthropogenic SO 2 emissions affect ocean productivity?

Abstract

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 SO 2 into the advecting dust plumes and subsequent acidification of the dust through heterogeneous SO 2 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 SO 2 . Significant gaseous HNO 3 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 SO 2 emissions from East Asia.