Multiphasic Redox Chemistry of Iron in Urban Atmosphere
A knowledge of the exact speciation of all oxidation states of transition metals in atmospheric water droplets as a function of variables such as pH, organic ligand content and ionic strength is critical to the computational assessment of in situ reaction pathways involving S(IV), O_2, RHCO, NO_x, ROOH, and H_2O_2. Likewise, a knowledge of the speciation of metals such as Fe and Mn in wet and dry atmospheric deposition and the subsequent speciation changes upon introduction to marine waters is important to the assessment of the ability of marine biota to utilize these elements for nutritional needs. Iron is emitted to the troposphere from both natural (e.g., windblown dust) and anthropogenic (e.g., coal combustion) sources. It has been proposed that atmospheric Fe participates in a variety of reactions such as the oxidation of S(IV) and organic compounds by Fe(III) via direct electron transfer, and the catalytic auto-oxidation of SO_2 to SO_4^(2-) in the droplet phase.
© 1994 Air & Waste Management Association. The authors wish to thank Drs. George Luther, Tom Church, Alan Veron and the crew of R.V. Cape Henlopen, the College of Marine Studies at the University of Delaware, Cliff Weinman and his staff at the FAA radar facility in San Pedro, Drs. Ted Murphy and Mell Dutton of the CSU Bakersfield, and the staff of LA county fire department at Henninger Flats for their help. The authors also wish to thank J. J. Morgan, B. Faust and J. Winchester for their helpful comments and R. Siefert for sharing some of his aerosol results. Support was provided by grants from the NSF (ATM 9015775 & OCE 8916804)