New method for sizing insoluble residues in precipitation

In December of 2014, the first Ault Group publication came out in Aerosol Science and Technology (abstract). First author Dr. Jessica Axson worked in collaboration with Dr. Jessie Creamean of the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado, Boulder on the paper entitled “An in situ method for sizing insoluble residues in precipitation and other aqueous samples” (Aerosol Science And Technology 49(1): 24-34). The work examines the size distribution and number concentration of insoluble residues with in snow collected at Yosemite National Park, CA and rainwater collected in Ann Arbor, MI using a new a novel technique for environmental analysis known as Nanoparticle Tracking Analysis (NTA). This technique uses Brownian motion of particles in a liquid to determine their hydrodynamic size. This technique has great potential for studying the role that insoluble residues play in critical atmospheric processes, such as droplet/crystal nucleation, cloud processing, dry deposition, scavenging, and more.

The work was presented at the AGU Fall Meeting in December 2014 in San Francisco, CA.  Summer students from the first ever UM Detroit Research Internship Summer Experience (D-RISE) Partnership with Cass Technical High School in Detroit, Desmond Madu and Jackelyn Rodriguez, were able to participate in the project by assisting with rain sample collection and analysis.

Figure: a) NanoSight™ LM10, b) schematic of the laser illumination device (courtesy of Malvern, Inc.), c) Brownian motion (red lines) of individual nanoparticles (green spheres), and d) number size distributions.