THE BROMINE CONTENT OF MICROMETEORITES - ARGUMENTS FOR STRATOSPHERIC CONTAMINATION

Bromine-salt nanocrystals are associated with a porous chondritic micr ometeorite (W7029E5) that was collected in the lower stratosphere. The se salt nanocrystals occur together with volcanic Na and K salt nanocr ystals embedded in sulfuric acid droplets that were originally adhered to the particle. These materials were concentrated during hexane rins ing as part of routine curation procedures at the NASA Johnson Space C enter Cosmic Dust Curatorial Facility. This observation is fortuitous to the extent that the concentration of nanocrystals and sulfuric acid is an experimental artifact of curation. If bromine is a stratospheri c contaminant due to surface adsorption, there should be a positive li near relationship between the mass-normalized residence time and bromi ne content of individual micrometeorites. I show that the predicted co rrelation exists using a new model to calculate the stratospheric resi dence time of individual nonspherical micrometeorites in the slow-sett ling Wilson-Huang regime of the stratosphere.