Environmental Science: Processes & Impacts blog

Karen C. Dannemiller, PhD is an Assistant Professor at Ohio State University with a joint appointment in Civil, Environmental, and Geodetic Engineering and Environmental Health Sciences. She also has a courtesy appointment in Microbiology. At Ohio State, she leads the Indoor Environmental Quality (IEQ) (https://ieq.engineering.osu.edu/) group and studies the indoor microbiome and indoor chemical exposures. In 2017, she was awarded the Denman Distinguished Research Mentor Award.

Prior to her current position, Dr. Dannemiller graduated with honors in Chemical and Biochemical Engineering from Brown University and earned her MS, MPhil, and PhD at Yale University in Chemical and Environmental Engineering. During this time, she completed an internship at the California Department of Public Health in the Indoor Air Quality Program. She was also a Microbiology of the Built Environment Postdoctoral Associate at Yale University

Read Karen Dannemiller’s Emerging Investigator article “Degradation of phthalate esters in floor dust at elevated relative humidity” and find out more about her in the interview below:

Your recent Emerging Investigator Series paper focuses on the degradation of phthalate esters in floor dust at elevated relative humidity. How has your research evolved from your first article to this most recent article?

This paper has really allowed my work to come full circle.  My first research paper was on formaldehyde in the indoor environment, which was based on my work in the chemical engineering department at Brown University as an undergraduate.  During my PhD, I began to focus more on microbial exposures in the indoor environment.  This Emerging Investigator Series paper is so exciting because it combines my interest in both indoor chemistry and indoor microbiology by examining the interactions between these two systems.

What aspect of your work are you most excited about at the moment?

I direct the Indoor Environmental Quality Laboratory at Ohio State University, and I am excited about all the applications that we are discovering to which we can apply our research. It is so critical to understand the chemical and microbial processes occurring in the indoor environment, and this has important implications in many different systems.  These processes can be particularly important in influencing exposures of vulnerable populations, such as asthmatic children.  We also need a thorough understanding of chemical and microbial interactions in specialized, sensitive systems such as on the International Space Station.  I am most excited to have received grants from NIH, NASA, the Alfred P. Sloan Foundation, and other organizations to study these interactions.

In your opinion, what are the most important questions to be asked/answered in this field of research?

Right now, very little is known about the interactions between chemicals and microbes in the indoor environment.  There are a plethora of questions that need to be asked to gain even a basic understanding of what is happening around us on a daily basis.  These may have important implications for our health.

What do you find most challenging about your research?

One of the most challenging but also exciting aspects of my research are the unexpected surprises inherent in any scientific dataset, but especially rich microbial datasets.  Often, future grant proposals can result from novel associations discovered during data analysis.

In which upcoming conferences or events may our readers meet you?

The next conference I will attend will be AEESP in Tempe, AZ, May 14-16, 2019.  I am very excited to be giving the plenary talk on Thursday morning.

How do you spend your spare time?

I love spending time with my family.

Which profession would you choose if you were not a scientist?

If I were not a research scientist, I would be an environmental public health practitioner.  They apply scientific principles to help people reduce their harmful exposures.  I appreciate the hard, challenging work that they do everyday, especially in fields like mold remediation.

Can you share one piece of career-related advice or wisdom with other early career scientists?

I have been very lucky and very thankful to have some outstanding mentors throughout my career.  I would highly recommend that early career scientists find mentors to help them navigate different obstacles they may encounter.  Mentors are a great source of advice and inspiration.  They can also help you identify exciting opportunities

Nathaniel Warner is currently an Assistant Professor at The Pennsylvania State University in the Department of Civil and Environmental Engineering. Previously, Dr. Warner received a BA from Hamilton College where he majored in Geology, an MS in Hydrogeology from Miami University in Oxford, Ohio and a PhD in Earth and Ocean Sciences from Duke University. He was the Joseph B Obering Postdoctoral Fellow, Dartmouth College, Department of Earth Sciences from 2013-2015. His current research focuses on using B, Sr, and Ra isotope geochemistry to better understand the processes controlling 1) salinization of freshwater 2) the fate and transport of metals in oil and gas produced waters once released to the environment, and 3) treatment technologies for oil and gas produced waters. Dr. Warner’s lab group has used Sr and Ra isotopes to trace the accumulation of metals associated with oil and gas wastewaters in both sediment and freshwater bivalves. His work has been published in Proceedings of the National Academy of Sciences-USA, Environmental Science and Technology, Applied Geochemistry, Geochimica et Cosmochimica Acta, Chemical Geology and Environmental Science: Processes and Impacts.

Read Dr Nathanial Warner’s Emerging Investigator article “Radium accumulation in carbonate river sediments at oil and gas produced water discharges: implications for beneficial use as disposal management” and read more about him in the interview below:

Your recent Emerging Investigator Series paper focuses on radium accumulation in carbonate river sediments at oil and gas produced water discharges. How has your research evolved from your first article to this most recent article?

Based on the results from the first article we expected oil and gas discharges to behave in a similar way, but that was not the case with our recent findings. Instead of radium being associated with barite (which is commonly discussed in the literature) in the most recent study we found the control on radium in sediments was the carbonate precipitation. This leads us to think that each oil and gas basin has varying geochemistry of its produced waters and each could have a different story to tell about fate and transport of radium (or other contaminants of concern) once discharged to the surface.

What aspect of your work are you most excited about at the moment?

Treatment technologies for the high salinity brines. It’s a challenge, but breakthroughs and the chance to make a big difference in how these waters are managed is exciting.

In your opinion, what are the most important questions to be asked/answered in this field of research?

How do we get radium out of high salinity fluids in an economic way? And where does the radium ultimately end up once released to the surface?

What do you find most challenging about your research?

Environmental samples, especially for radium often have large natural variations that can make clear trends or impacts difficult to quantify. We therefore need to make multiple measurements on a variety of samples to get at a reliable data set.

In which upcoming conferences or events may our readers meet you?

Goldschmidt – Barcelona and WRI16 – Siberia

How do you spend your spare time?

Outdoor activities, biking hiking, running.

Which profession would you choose if you were not a scientist?

Astronaut- but I suppose most of those folks are scientists…. How about an artist? I really enjoy creating things with my hands so maybe I would be sculpting.

Can you share one piece of career-related advice or wisdom with other early career scientists?

Don’t give up on your career goals, but also don’t be afraid to take an indirect path to get there. All of the experiences along the way will make you a better researcher.

Ryan Sullivan is an Associate Professor at Carnegie Mellon University, with a joint appointment in the Departments of Chemistry and Mechanical Engineering, and a courtesy appointment in the Department of Civil and Environmental Engineering. He is also a faculty member in the Center for Atmospheric Particle Studies, and the Associate Director of CMU’s Institute for Green Science. His primary interest is understanding the sources and chemical evolution of atmospheric aerosol particles, and how this evolution in turn alters the particle’s ability to nucleate clouds and thus alter climate. His research group at CMU develops analytical techniques for real-time analysis of individual aerosol particle composition used in his research. These include laser ablation single-particle mass spectrometry, aerosol optical tweezers, and microfluidic devices for ice nucleation measurements. The multi-phase chemical evolution of biomass burning aerosol from wood smoke is a major current focus. Ongoing experimental investigations include the alteration of the ice nucleation properties of smoke particles induced by chemical aging; and the activation of photo-labile chlorinated gases from heterogeneous reactions of nitrogen oxides with chloride salts emitted in the smoke. He has recently started new initiatives to develop and rigorously test advanced oxidation methods for the biosafe removal of micropollutants from wastewater.

Ryan obtained his Hon.B.Sc. in chemistry from the University of Toronto, and his M.Sc. and Ph.D. in chemistry from the University of California, San Diego. Before moving to Carnegie Mellon University in 2012, he completed his postdoctoral research in atmospheric chemistry at Colorado State University. Ryan is the recipient of a Faculty Early Career Development (CAREER) award from the National Science Foundation, and the National Academy of Science’s Cozzarelli Prize.

Read his Emerging Investigator Series article “Determination of biphasic core–shell droplet properties using aerosol optical tweezers” and find out more about him in the interview below:

Your recent Emerging Investigator Series paper focuses on the determination of biphasic core–shell droplet properties using aerosol optical tweezers . How has your research evolved from your first article to this most recent article?

The aerosol optical tweezers technique is a powerful approach to studying individual levitated particles. I started using optical tweezers six years ago, and we built two custom systems in my lab. One is for low temperature work to study ice nucleation, and the other has better controlled mixing and flow regimes for studying organic aerosol particles; that is the system used here. We recently reported the first aerosol optical tweezers experiments on complex secondary organic aerosol (SOA) that was produced and condensed onto a droplet directly in the tweezing chamber. We found that most of the SOA phase separated from the original droplet, be it a hydrophobic or aqueous phase, to form a core-shell morphology. We also observed strong evidence for a stable emulsified state of small SOA particles circulating in an aqueous droplet core. To more deeply investigate the chemical properties of these core-shell particle morphologies required us to develop the sophisticated analysis algorithm that we report here. This allows us to determine the properties of both the core and shell phases by analyzing the whispering gallery modes present in the Raman spectrum that form a standing wave around the droplet’s core and shell phases. It was Kyle Gorkowski who advanced upon the existing WGM analysis algorithms, drawing on his aerosol optics background to improve the accuracy and computational efficiency of this fitting algorithm.  I have never worked on spectral analysis algorithms before and this research is a nice example of how new scientific discoveries drive the creation of advanced data analysis methods, allowing us to probe environmental chemical systems more deeply.

What aspect of your work are you most excited about at the moment?

There has been a lot of interest in atmospheric chemistry recently in the role that particle morphology plays in determining how particles interact with and affect their surrounding environment. This changes how particles interact with radiation, with water vapor and clouds, and with trace gases that can react heterogeneously with particle surfaces, and the partitioning of gases into organic or aqueous particle phases. As each particle’s composition and morphology can be quite different from one and other, it is important to determine these properties at the individual particle level. Determining particle morphology is quite difficult, but aerosol optical tweezers provides a powerful way to do this in a direct manner on single levitated particles. The analysis algorithm we reported here allows us to better and more quickly determine the properties of core-shell morphologies. I’m excited to continue to use optical tweezers as a powerful physical chemistry experiment to investigate complex and realistic atmospheric particle systems. We’re now starting to use our core-shell analysis algorithm to investigate the interplay between a particle’s morphology and how it reacts heterogeneously with trace reactant gases.

In your opinion, what are the biggest advantages of the new algorithm presented in your paper over previous methods of analysing data from core-shell biphasic droplets?

When we first started analyzing core-shell droplets it would take hours just to fit one Raman spectral frame. We acquire a new droplet spectrum every 2 seconds, and often conduct experiments on a single droplet for hours, so this analysis was completely impractical. Thanks to the clever approaches that Kyle worked out, our new algorithm is much more efficient and can fit each spectrum in much less than a minute. We’re now able to analyze hours-long experiments and observe the properties of core-shell droplets evolve during these long experiments that simulate how particles might evolve during atmospheric transport. We now also have a much deeper understanding of the accuracy of our algorithm’s analysis of core-shell droplets and how this accuracy changes with the quality of the spectral data and number of whispering gallery modes present. This gives us much more confidence in the accuracy of any properties that we determine from biphasic droplets.

What do you find most challenging about your research?

Aerosol particles are really tough to do experiments on. This makes this research a fun challenge, but it can be very challenging indeed. A whole suite of expensive instruments is often required to determine all the different aerosol properties you need to know to understand their chemistry. As the submicron particles are so small and have very little mass, they are difficult to study at the individual particle level, and prone to change during analysis. If you just look at the particles they will change; they are constantly evolving. So you have to design your experiments very carefully, and always be open to unexpected surprises. That’s what makes the aerosol optical tweezers approach so powerful. We are constantly determining the properties of an individual particle as it continues to evolve so we know its entire life history. That allows us to answer important questions in a unique way, such as how do particles evolve as they move through the atmosphere and interact with light, water, other particles, and condensible or reactive gases?

In which upcoming conferences or events may our readers meet you?

This summer I’m helping to run a Workshop on “Aerosols and Clouds: Connections from the Laboratory to the Field to the Globe” at the Telluride Science Research Center in Colorado. Then in September I’ll be attending the International Aerosol Conference in St. Louis, Missouri. There I’m organizing a Special Symposium on “Unraveling the Many Facets of Ice Nucleating Particles and Their Interactions with Clouds”, and I’m the Chair of the working group on Instrumentation & Methods and helped organize more than 150 abstracts submitted to that topic. The International Aerosol Conference only takes place every 4 years, and comes to North America every 12 years, so it’s a great opportunity to interact with a wide range of international scholars who are all advancing our understanding of these complex, tiny, airborne particles.

How do you spend your spare time?

These days I play a lot of volleyball (indoor, on grass, and beach). Playing sand volleyball is the closest we get to going to the beach in Pittsburgh! Being 6’3” is a slight advantage in volleyball, but less so for the olympic lifting I also do. I also like to go hiking on the many trails we have in Appalachia.

Which profession would you choose if you were not a scientist?

I had to think about this one for awhile. I would probably work more on developing technology to help tackle important environmental problems, such as improved methods to remove pollutants from our air and water, and to prevent them from being produced in the first place. I suppose that still sounds like science though… A career working with environmental advocacy groups and NGOs to help raise awareness of environmental issues and educate young students and the general public about the environment would also be very satisfying.

Can you share one piece of career-related advice or wisdom with other early career scientists?

It’s really important to find research questions and topics that greatly speak to you. All research is hard to complete, especially when you’re starting your own lab, so why work on science that doesn’t really excite you? That passion will help propel you through the challenging parts. It’s also important to carve out your niche in research – what will you become known for? That doesn’t mean you have to try doing completely different new-to-you research from the start. Having a good balance of safer close-to-home and riskier but more innovative research projects is a good approach.

We are delighted to introduce our latest Environmental Science: Processes and Impacts Emerging Investigator, Ning Dai!

Dr. Ning Dai is an Assistant Professor in the Department of Civil, Structural and Environmental Engineering at the University at Buffalo. Her research areas include disinfection processes for wastewater reuse and the fate of agrochemicals in natural systems. Ning received her B.S in Environmental Science and Engineering from Tsinghua University in China, M.S. in Civil and Environmental Engineering from Stanford University, and Ph.D. in Chemical and Environmental Engineering from Yale University. She joined the University at Buffalo in 2014 after a brief postdoctoral training in Stanford University. Dr. Dai is a recipient of the National Science Foundation CAREER Award.

Read her Emerging Investigator Series article: ‘Sunlight photolysis of 2,4-D herbicides in systems simulating leaf surfaces’ and find out more about her in the interview below:

Your recent Emerging Investigator Series paper focuses on sunlight photolysis of herbicides in systems simulating leaf surfaces. How has your research evolved from your first article to this most recent article?

This is actually my first article on photochemistry in natural systems. My past research mainly focused on engineering systems such as amine scrubbers for carbon capture and disinfection and oxidation processes for water reuse. As a PhD student, I only had a short project on tetracycline photolysis in my first semester; however, I was continuously exposed to photochemistry from group meeting presentations and from the discussions with one of my lab mates, who is an excellent photochemist. After I started my own group at University at Buffalo, I thought it would be interesting to pursue some projects in this topic. I still have a lot to learn in photochemistry, but I think that is the exciting part to be in academia – there are always new things to learn and discover!

What aspect of your work are you most excited about at the moment?

I am generally excited about learning. My students and I are learning new methods and analytical tools to try to answer new research questions. I find that a rewarding experience.

In your opinion, what is the biggest environmental impact presented by the photolysis of herbicides on leaf surfaces?

I believe further understanding of herbicide photolysis on leaf surface can improve the environmental fate model for pesticides. Currently, pesticide transformation on plant surface is not considered in the fate model, but it can be important for some pesticides. For example, we showed in this study that the photolysis of 2,4-D herbicides on surface can proceed at comparable rates as their biodegradation. This is noteworthy because biodegradation is considered to be the most important degradation pathway in the current fate model.

What do you find most challenging about your research?

To study photochemistry on plant surface, it is challenging to create well-controlled and yet environmentally relevant experimental conditions. This, I believe, also applies to any research involving heterogeneous systems.

In which upcoming conferences or events may our readers meet you?

I will be attending the American Chemical Society Fall Meeting in Boston this August. My student Lei Su (first author of this paper) will be presenting at the ARGO division.

How do you spend your spare time?

I enjoy swing dance, although I don’t get to dance as frequently as I did in graduate school. I guess it is somewhat busy to be a new faculty!

Which profession would you choose if you were not a scientist?

I believe I would be a full-time teacher (that is part of the university faculty job description as well). I enjoy the process of sharing knowledge.

Can you share one piece of career-related advice or wisdom with other early career scientists?

In my own experience as a PhD student, I learned a lot from my research group; not only on my dissertation projects, but also on the research topics I was not involved in. Similarly, I also learned from friends in other research groups and even other departments. The benefits extend beyond scientific knowledge, and include many great advices on career development. I consider peer learning a crucial component of the graduate school experience, and I would recommend everyone to fully engage in it.