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

Abstract

Abstract:In order for Fe contained in aeolian dust to act as a micronutrient for oceanic phytoplankton it must be first mobilized or dissolved. We propose that significant Femobilization can occur in mineral dust from East Asia as a result of the incorporation of SO 2 from pollutant emissions into the advecting dust plumes and the subsequent acidification of the dust by heterogeneous SO 2 oxidation. To test this acid-mobilization hypothesis, we consider a dust plume that originated from the gobi deserts and advected over the Yellow Sea in March of 2001. Data collected during the TRACE-P field campaign confirm that this plume contained high concentrations of both dust and SO 2 .Measurements within the plume of significant concentrations of gaseous HNO 3 suggest that the dust particles were highly acidified (i.e., pH< 2). At these pH's, approximately 1-2% of the Fe contained in a deliquescent mineral dust particle would be mobilized within the nominal 3-5 day lifetime of the particle. These results suggest that there may be a link between the rate of C-fixation in so-called High-Nitrate-Low-Chlorophyll regions of the ocean and the rate of SO 2 emissions from East Asia.2

Understanding the nature of atmospheric acid processing of mineral dusts in supplying bioavailable phosphorus to the oceans

“…This cycling between cloud droplets and wet aerosol particles can occur several times [an average of 10 cycles throughout the troposphere (18)] before the aerosol drops to earth by wet or dry deposition. Thus, the chemical conditions within and between clouds are very different, with relatively high pH and low IS in cloud droplets and low pH and high IS in wet aerosols (20)(21)(22). This cycling was investigated for its effect on Fe dissolution in the atmosphere by Shi et al (23), who show that Fe is solubilized in wet aerosols and then reprecipitated as Fe nanoparticles in clouds.…”

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

“…It affects the solubility of trace metals and thus aerosol toxicity (Ghio et al, 2012;Fang et al, 2017). Low pH may enhance iron mobility in dust and impact ocean productivity (Meskhidze et al, 2003).…”

57Fe Mössbauer spectroscopy investigations of iron phase composition in fluidized beds from the ELCHO power plant in Chorzów, Poland

“…In this case, the ultrafi ne iron can be emitted into the atmosphere in the form of an ultrafi ne aerosol in association with residual amounts of soot. While soils exhibit relatively low levels of solubility in iron, the high solubility of atmospheric iron observed in fi eld studies has been explained by the atmospheric chemical processing of dust particles during long-distance transportation [10]. Also, it was suggested from in vitro studies that ferric iron in an aluminosilicate glass phase served as the source of bio-available iron from coal fl y ash and that the process of making iron bio-available depends on the size of ash particles [11,12].…”