Coal fly ash as iron source in atmospheric dust.

Anthropogenic coal fly ash (FA) aerosol may represent a significant source of bioavailable iron in the open ocean. Few measurements have been made that compare the soly. of atm. iron from anthropogenic aerosols and other sources. We report here an investigation of iron dissoln. for three FA samples in acidic aq. solns. and compare the solubilities with that of Arizona test dust (AZTD), a ref. material for mineral dust. The effects of pH, simulated cloud processing, and solar radiation on iron soly. have been explored. Similar to previously reported results on mineral dust, iron in aluminosilicate phases provides the predominant component of dissolved iron. Iron soly. of FA is substantially higher than of the cryst. minerals comprising AZTD. Simulated atm. processing elevates iron soly. due to significant changes in the morphol. of aluminosilicate glass, a dominant material in FA particles. Iron is continuously released into the aq. soln. as FA particles break up into smaller fragments. These results suggest that the assessment of dissolved atm. iron deposition fluxes and their effect on the biogeochem. at the ocean surface should be constrained by the source, environmental pH, iron speciation, and solar radiation. [on SciFinder(R)]