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.

Volunteering with FEMMES

On February 26th two graduate students Amy Bondy and Becky Craig, went to Howe Montessori School in Dearborn, MI with the FEMMES volunteer program. FEMMES (Females Excelling More in Math, Engineering, and Science) is dedicated to empowering  girls and young women as students and practitioners in STEM fields. Working specifically in diverse, underserved communities, FEMMES creates collaborative teaching and learning environments to promote leadership development, technical skills and self-confidence in women of all ages. Engaging, hands-on activities in all FEMMES programs allow girls to learn in a fun, supportive environment and explore their potential in the STEM fields. FEMMES seeks to build our participants’ curiosity about a variety of areas related to science, math, and engineering and encourage them to increase their participation in those fields.

At this after-school activity, Becky and Amy worked with groups of 4th-6th grade girls to explore various scientific concepts through hands-on activities. The girls explored electricity and circuits using conductive Play-Doh, batteries, light bulbs and buzzers (see image above), they investigated the properties of magnets and built an electromagnet using wire and a battery (see image below), they learned about catalytic reactions by creating "elephant's toothpaste" which involved the decomposition of hydrogen peroxide into oxygen and water, and finally built edible DNA structures using marshmallows, toothpicks, and Twizzlers.

Congratulations to Hongru

Hongru Shen a second year masters of science student in the Ault Lab received a Rackham International Student Fellowship in the amount of $10,000 for 2014-2015. She was first nominated by the Department of Environmental Health Sciences this October and this week chosen as one of only twenty-five International Student Fellowship awards campus-wide for 2014-15 at the University of Michigan. She says, "I feel honored to be awarded as a master student since this fellowship not only supports part of my next semester’s tuition but it reflects the Rackham Graduate School’s very positive assessment of my future success." Congratulations Hongru!

AAAR Annual Conference

Last month, October 20-24, second-year master student Hongru Shen (me) and Prof. Andrew Ault traveled to Orlando, FL to attend the 33^rd Annual Conference of the American Association for Aerosol Research (AAAR). Prof. Ault presented the latest research findings of single particle diversity and its impact on heterogeneous reactivity during the SOAS field, which was really exciting.

I presented a poster of my work, elemental and individual particle analysis of atmospheric aerosols from New Delhi, India. Few particulate matter studies conducted in New Delhi have focused on individual atmospheric particles, with most studies confined to bulk particles analysis. The lack of such studies in New Delhi has motivated this work investigating the particle sources and processing in the atmosphere. Both natural and anthropogenic sources were determined.  During this analysis process, I discovered an unexpectedly large number of lead-rich particles in New Delhi – even though lead has been phased out of gasoline since 1998. By further examining the chemical composition, size distribution, and morphological characteristics of these lead-rich particles, all of properties indicate that a poor regulation of lead-acid battery recycling is likely the major source. This is further confirmed by the spatial variability of the lead concentrations.

Presenting these results were extremely rewarding. I was able to show experts in the aerosol field, including our great collaborators, the findings I discovered. I was also very excited to talk with someone from India, during which I further confirmed the two sources of salt particles.

I also served as the student assistance of the AAAR, which is a unique way to interact with these excellent researchers. Meeting several people whose names always appear on papers makes reading a new experience in the future as I can match faces with their names on the page. Overall, AAAR was a fascinating time, which confirmed my determination to work in the aerosol field. And I will be very excited if I can return in the future.

UMBS Field Study - Round 1

Looking up to the top of the 100ft tower

Daniel Gardner (me), Nate May, Professor Kerri Pratt and Professor Andy Ault all traveled to the University of Michigan Biological Station (UMBS) in Pellston, Michigan to begin a summer field campaign studying the size distribution, concentration, and composition of aerosol particles in the region. Also joining us was Professor Steve Bertman from Western Michigan University and Stephanie Schmidt, an REU student from Michigan State University, spending her summer up as an REU student at UMBS.

The main site of the study is the PROPHET (Program for Research on Oxidants: PHotochemistry, Emissions, and Transport), a 100 foot tower reaching above the treetops with a wide variety of instrumentation and lines for pulling gases and particles down to the lab at the base of the tower.

The inside of the PROPHET lab with all current instruments

The gas and particle lines - covered with reflective insulation

Since the groups involved with the study will be analyzing both gases and particles, two separate lines were needed coming down the tower. A glass manifold is already installed on the tower from a previous study, and needed to be thoroughly cleaned after a long winter, as many bugs had flown into the pipeline and died. Cleaning a 100+ foot glass pipeline is no small task. It required a highly advanced piece of technology: a rag with 100 ft of rope tied to either side. Two teams were set up, one at the top of the tower and one at the bottom. The rag was dropped down and pulled back up the tube several times to scrub it clean. A bucket of water was lifted to the top of the tower to clean the rag in between each scrub. While cleaning and reassembling the pipeline, we had to pick up the pace, as a rainstorm was approaching, and it is quite unsafe to be on the top of the tower, as rain can make tower slippery and the descent unsafe.

The insluated copper tube sticking out of Lakeside Lab

The next step was to install a 100ft copper tube for the particle line, which was also a daunting task. The top of the copper coil was attached to a pulley system, and slowly lifted to the top of the tower, while the coil was straightened out. The tubing was secured to the tower with high strength cable ties, and then the entire length was wrapped with foam insulation and reflective tape to keep the temperature inside constant.There aerosol line was brought inside the lab on the ground, where it will connect to a variety of instruments. Only a few were set up so far - a Aerodynamic Particle Sizer (APS) and a Scanning Mobility Particle Sizer (SMPS) - two instruments designed to measure the size distribution of the particles. We will return in the future with many more instruments to add.

We also set up the same set of instruments at another location - at Lakeside Lab - a research facility located on the shore of Douglas Lake at UMBS. We set up another 10 feet of copper tubing to stick out the window of the lab, and connected it to the same instruments (APS + SMPS). This way we can compare the sizes of particles from above the canopy vs particles from the lake.




We would like to thank Professor Bertman for all of his help in setting up all the lines and instruments at the two labs, and Stephanie for monitoring all of the instruments while we are not there!

Daniel Gardner (Left), Stephanie Schmidt (Right)

Stephanie (Left), Professor Bertman (Center), Professor Andy Ault (Right)

Molina Symposium

On May 12, 2014, Prof. Andrew Ault attended the Molina Symposium in La Jolla, CA to honor Professor Mario Molina. Molina is a celebrated chemist and Nobel Prize recipient; he won the Nobel Prize in chemistry in 1995 along with Paul J. Crutzen and F. Sherwood Rowland for their discovery of the role of CFCs (chlorofluorocarbons) in ozone depletion. This symposium took place at the Scripps Institution of Oceanography UC San Diego since Molina moved to UCSD in 2005 from MIT to research the chemical properties of atmospheric particles and the effect of these particles on clouds and climate. At this symposium, Dr. Ault presented a poster concerning the spectroscopic and microscopic analysis of particles from SOAS.

 

Picture of Dr. Ault showing the work of grad student Amy Bondy on particle analysis from the SOAS campaign.

Michigan Geophysical Union Poster Presentation

Graduate student Hongru Shen presented her work on the analysis of atmospheric aerosol particles from New Delhi, India at the Michigan Geophysical Union Meeting at the University of Michigan on April 7.  Several students from the Pratt lab, as well as students from the Earth and Environmental Sciences and Atmospheric, Oceanic and Space Sciences departments, also presented in the poster session.