BISMUTH OXIDE NANOPARTICLES IN THE STRATOSPHERE

Platey grains of cubic Bi2O3, alpha-Bi2O3, and Bi2O2.75 nanograins wer e associated with chondritic porous interplanetary dust particles W702 9C1, W7029E5, and 2011C2 that were collected in the stratosphere at 17 -19 km altitude. Similar Bi oxide nanograins were present in the upper stratosphere during May 1985. These grains are linked to the plumes o f several major volcanic eruptions during the early 1980s that injecte d material into the stratosphere. The mass of sulfur from these erupti ons is a proxy for the mass of stratospheric Bi from which we derive t he particle number densities (p m(-3)) for ''average Bi2O3 nanograins' ' due to this volcanic activity and those necessary to contaminate the extraterrestrial chondritic porous interplanetary dust particles via collisional sticking. The match between both values supports the idea that Bi2O3 nanograins of volcanic origin could contaminate interplanet ary dust particles in the Earth's stratosphere.