Prof. Ault Interview with Water Center Newsletter

Prof. Ault Interview with Water Center Newsletter

New Review on Methods for Atmospheric Aerosol Chemistry Research

A new review from the Ault Group (Prof. Ault and Dr. Jessica Axson) is focused on advances in atmospheric aerosol instrumentation in the past 5 years. The title is " Atmospheric Aerosol Chemistry: Spectroscopic and Microscopic Advances" and it was included in Analytical Chemistry's "Fundamental and Applied Reviews in Analytical Chemistry 2017". Instrumentation used for aerosol analysis ranging from electron microscopy to Raman microspectroscopy to optical tweezers and many more are covered. The motivation for using these methods, such as physicochemical mixing state as well as instrumental size ranges are discussed.

Prof. Ault receives CAREER grant from National Science Foundation

Prof. Ault was recently awarded a CAREER grant from the National Science Foundation entitled " CAREER: Molecular Studies of Phase Separations and Internal Structure in Individual Particles" This grant will focus on understanding the molecular level processes occurring within complex atmospheric aerosol particles. The research will couple new instrumentation (atomic force microscopy with infrared - AFM-IR) with existing instrumentation used by the Ault Group (Raman microspectroscopy and electron microscopy). New information about how aerosols change as a function of relative humidity (RH) with respect to viscosity and phases separations will be determined for particles of different sizes and compositions. Learn more at NSF.gov

https://www.nsf.gov/awardsearch/showAward?AWD_ID=1654149

Prof. Ault elected as Vice-Chair of the Atmospheric Chemistry Working Group for AAAR

Dr. Ault was elected this week as the vice-chair of the "Atmospheric Chemistry" working group for the American Association for Aerosol Research (AAAR). This position is elected across the entire AAAR membership. From AAAR "These leaders are selected for a 2-year rotation, serving as Vice-Chair for the first year and then becoming Chair for the second year. The Chair presides over the WG meeting at the annual conference and then serves on the conference program committee, planning the next year's annual conference." Dr. Ault is excited to provide service to a community he has been involved with for the past decade!

D-RISE Summer 2016 Internship

This summer, the Ault lab participated in the Detroit Research Internship Summer Experience (D-RISE) for the third year. Our student, Stephanie Camarena, a rising senior at Cass Technical High School in Detroit, spent the seven week program working on a project measuring the pH of laboratory generated atmospheric aerosols. The D-RISE students were able to attend many events on the UM campus and within the Ann Arbor community over the course of their program, even meeting UM President Mark Schlissel! Check out this link to an article on the D-RISE students and program from the UM Diversity, Equity, & Inclusion website for more information!

Two new articles from joint Ault and Pratt Lab work on freshwater, or Lake Spray Aerosols (LSA), have been accepted to AMT and EST:

• “Lake Spray Aerosol Generation: A Method for Producing Representative Particles from Freshwater Wave Breaking” Nathaniel W. May, Jessica L. Axson, Alexa Watson, Kerri A. Pratt, and Andrew P. Ault, doi:10.5194/amt-2016-115. (http://www.atmos-meas-tech-discuss.net/amt-2016-115/)
• “Lake Spray Aerosol: A Chemical Signature from Individual Ambient Particles” Jessica L. Axson, Nathaniel W. May, Isabel D. Colόn-Bernal, Kerri A. Pratt, and Andrew P. Ault (http://pubs.acs.org/doi/abs/10.1021/acs.est.6b01661)

Through laboratory experiments and a small field campaign, we have examined the relationship of LSA to bubble bursting dynamics (May et al.) and provide the first chemical signature for ambient LSA (Axson et al.). A LSA generator, utilizing a plunging jet, was constructed to create aerosols under isolated conditions from freshwater samples and model salt solutions. 

The LSA generator shown as a (a) schematic and (b) photograph

Systematic examination of model salts, synthetic freshwater, and Lake Michigan sample indicate that LSA is characterized by a larger bubble size distribution, compared to seawater, with a peak near 300 μm and a bimodal aerosol size distribution with a primary mode at 180 nm and secondary mode at 46 nm. The chemical signature for LSA was determined from ambient collected particles on the shore of Lake Michigan during a wave event in 2015 and surface freshwater from the same location run in the LSA generator. LSA composition was show to consist primarily of calcium carbonate and coupled to great lakes water chemistry (Ca²⁺>Mg²⁺>Na⁺> K⁺), making it chemically distinct from sea spray.

Schematic of ambient LSA from wave breaking on Lake Michigan

The study of LSA is needed as models, at present, utilize SSA parametrizations for freshwater systems, which are not accurate for predicting climate properties of LSA. Given the abundance of freshwater lakes globally, this can be a potentially important source of aerosols that may contribute to light scattering, cloud condensation nuclei (CCN) and ice nuclei (IN) concentrations, air quality, and health around the Great Lakes and other bodies of freshwater. 

Aerosol pH Paper Selected for JPC-A Virtual Issue

A recent paper led by Joel Rindelaub and Becky Craig from the Ault Laboratory on measuring the pH of individual aerosol particles was selected for a virtual issue of the Journal of Physical Chemistry - A focused on Atmospheric Physical Chemistry (link). From the journal's website:

"This collection contains 25 papers published in the Atmospheric Chemistry section of the Journal of Physical Chemistry A (JPC A) since 2013. The vision is that this collection will be useful for generating new ideas, pushing existing boundaries, and motivating new research in atmospheric chemistry. Moreover, this Virtual Issue may serve as a basis for assembling or updating a graduate course on atmospheric physical chemistry."
 
Great work Becky and Joel!