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Simulating the cloud processing of iron in Australian dust: pH and dust concentration
Author(s) -
Mackie D. S.,
Boyd P. W.,
Hunter K. A.,
McTainsh G. H.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl022122
Subject(s) - dissolution , extraction (chemistry) , environmental chemistry , reaction rate constant , dust storm , scavenging , chemistry , aerosol , mineralogy , kinetics , chromatography , physics , biochemistry , organic chemistry , quantum mechanics , antioxidant
We report on the simulated cloud processing of an aerosol iron sample derived from an Australian dust storm. Primary factors influencing the extent and rate of Fe mobilization were pH, duration of extraction and dust concentration. Fe was significantly mobilized below a threshold of pH ∼3.6. After initial rapid mobilization at low pH, the rate of Fe release was constant with constant pH. Between this threshold and pH ∼7.1, dissolved Fe fell to a minimum but above this pH further dissolution of iron occurs, probably due to the formation of soluble ferrates. At our lowest dust concentrations (1–20 mg L −1 ) the rate of Fe extraction at low pH was constant, while at higher dust concentrations the rate was inversely proportional to dust concentration. Dissolution of iron from dust is thus a complex process and these factors must be considered when modeling the input of iron to the oceans.