First Field Study - Dexter, Michigan

The Ault lab has just begun its first field study! The site is located north of Dexter, Michigan, which isn't too far away from the main University of Michigan campus in Ann Arbor, but it is a good start for field work. The site is owned by the university and is currently operated by Dr. Tim Dvonch, a professor in the Environmental Health Sciences department. The site is covered in several feet of snow, but has a wooden deck raised well above the ground to keep the instruments dry. This field study involves taking a Micro-Orifice Uniform Deposit Impactor (MOUDI) out to the site and measuring the amount and composition of aerosol particles in the air. The MOUDI is placed inside an electrical box to protect it from the environment and has a hole cut out of the top to allow for the aerosol inlet to stick out.
The MOUDI works by using a pump to suck in air and pass it through a series of stages. The size of the holes from one stage to the next and the air flow rate are designed to have only particles of a particular size collide on the substrates. Anything smaller than selected will travel with the air to the next stage. The stages are also rotating - this allows for a uniform deposit of particles, and prevents large piles from forming directly underneath each orifice. On top of the MOUDI is a Cyclone, a specialized device that prevents anything larger than 10 microns from passing through. This prevents bugs or very large dust particles from clogging up all the tiny orifices. The cyclone is very heavy, and requires support or it will fall over with the MOUDI. By drilling another hole in the electrical box and setting the cyclone in the hole, we can stabilize the weight with the sturdy electrical box. The substrates are replaced twice each day for a day set and an overnight set. The substrates are placed in the fridge to prevent anything from happening between collection and analysis, and will be analyzed via SEM, TEM and Raman spectroscopy.
One of Dr. Dvonch's graduate students - Pearl Nathan - is also doing testing at the site, and provided a great deal of help in setting up the instrument. While it is extremely cold, the snowy site is a beautiful location. The study will run from Saturday, March 1st to Sunday March 9th, giving us plenty of samples to analyze and determine the composition of the air out here in Dexter.

Me (Daniel Gardner) with the MOUDI