Environmental Science: Processes & Impacts Collections

Environmental Science: Processes & Impacts (ESPI) is the home for high-impact research that advances our understanding of environmental chemistry in natural matrices. Here, we’ve brought together all of our latest Article Collections, Themed Issues, and Editor’s Choice collections to enable you to easily navigate to content most relevant to you. We hope you enjoy reading the papers in these collections!

Ongoing Collections:

Themed Issues: 

 


Editors’ Choice Collections: 

 

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Passive samplers for indoor applications: a step closer to a broader use

Written by Rachele Ossola

Polychlorinated biphenyls (PBCs) are a wide class of compounds with numerous everyday applications such as electrical insulators, cooling fluids, plasticizers and flame retardants – just to name a few. However,  back in the 1970s evidence started accumulating on their environmental persistency and on their toxicity as human carcinogens. In 1978, PBCs production was terminated and an international ban followed their inclusion in the Stockholm convention of Persistent Organic Pollutants. Interestingly though, PBCs are still present in our houses and schools today. A recent study conducted in rural and urban schools in the US measured indoor PBCs concentrations one to two orders of magnitude higher than outdoor values.1 Another study measured PBCs in residential homes and found kitchen cabinets to act as an indoor source of these semivolatile compounds.2 Considering their adverse health effects and their widespread occurrence, non-invasive, easy-to-use and cheap detectors are needed to monitor indoor PBCs levels.

In this respect, passive samplers represent a valid alternative to conventional sampling techniques. They consist of a disc of polymeric material placed into a protective shell. After the sampler is deployed in the environment, semivolatile compounds diffuse into the chamber and get absorbed onto the polymer. After a certain exposure time, the passive sampler is withdrawn from the field, and the absorbed compounds are extracted and quantified. The “on-the-sampler” concentration (Csampler) is then used to obtain environmental exposure values.

 

However, using passive samplers in an accurate and reliable manner is challenging. One of the most critical but elusive parameters is the sampling rate (Rs), which represents the volume of air sampled per unit of time and is required to correctly convert Csampler into exposure data. In outdoor applications the sampling rate is commonly measured using a “depuration compound”, an isotopically-labelled version of the species of interest that is adsorbed onto the polymeric disc before deploying the sampler in the field. The sampling rate is simply estimated from the loss of the depuration compound. This technique is effective, but the toxicity of these reference molecules makes it unsuitable for indoor applications. Another possibility involves the calibration of the passive sampler before its use, but this approach is time consuming and requires the use of an additional independent sampling method (for instance, an active air sampler).

Alternatively, Rs can be estimated with mathematical models. These models have already been developed for outdoor applications and allow the estimation of Rs from the wind speed data. Starting from this point, Herkert and Hornbuckle in their most recent publication hypothesized that these same models, if adjusted appropriately, can provide Rs from the indoor airflow data. To test their ideas, they set out a two-phase study with the final aim of providing practical recommendations for an accurate use of passive samplers in indoor environments.

In the first phase, they measured the sampling rate of thirty-eight PBCs congeners in a school room using a combination of passive and active samplers, and compared the results with the modelled values. The predicted Rs values were obtained from the room-averaged wind speed, a parameter that can be easily measured with an anemometer. Their results showed that the difference between the empirical and the simulated values was on overall less than 25%, demonstrating that mathematical models represent a reasonably good method to access sampling rates.

In a second phase, they investigated how the position of the passive sampler within the room influenced the value of the sampling rate. They observed that location did matter, as different zones of the room experienced different air flow. Specifically, fluid dynamics simulation of a typical room showed that samples placed close to the walls (< 30 cm), the ceiling (< 30 cm), the air diffuser (< 50 cm) or placed on surfaces experience unrepresentative wind speeds, while open or closed doors seem to have a minimal effect. They thus concluded that Rs can be modelled accurately if the passive samplers are placed appropriately, opening up this technology for use in indoor settings.

To download the full article for free*, click the link below:

Effects of room airflow on accurate determination of PUF-PAS sampling rates in the indoor environment

Nicholas J. Herkert and Keri C. Hornbuckle

Environ. Sci.: Processes Impacts, 2018, 20, 757

DOI: 10.1039/c8em00082d


About the Webwriter:

Rachele Ossola is a PhD student in the Environmental Chemistry group at ETH Zurich. Her research focuses on photochemistry of dissolved organic matter in the natural environment.

 

 

 


References in article:

(1)        Marek et al., Environ. Sci. Technol. 2017, 51 (14), 7853–7860.

(2)        Herkert et al., Environ. Sci. Technol. 2018, 52 (9), 5154–5160.

*Article free to access until the 1st of January 2019

 

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Latest Advances in the Analysis of Complex Environmental Matrices

We are delighted to highlight the Latest Advances in the Analysis of Complex Environmental Matrices meeting that takes place at the Royal Society of Chemistry’s London office, Burlington House on 22nd February 2019. 

The meeting highlights advances in the analysis of complex environmental matrices (soils and sediments, water and air) by GC, HPLC and MS and also the use of cheminformatics and it will include a number of interesting talks from keynote speakers listed below.  There will be coffee and lunch breaks and a vendors’ exhibition around midday. For the full schedule, click the link below:

Find out more about the event and register here

Keynote speakers and talks include:

Mixing high-resolution chemical analysis and machine learning in ecotoxicology for aquatic invertebrates

Dr Leon Barron (King’s College London)

Temporal and spatial variation in pharmaceutical concentrations in an urban river system

Prof. Alistair B.A Boxall (University of York)

Liquid chromatography/quadrupole time-of-flight mass spectrometry screening of polar pollutants sequestered by passive sampling devices at the river catchment scale

Prof. Gary Fones (University of Portsmouth)

Micro- and nano-plastic pollution of freshwater and wastewater treatment systems

Dr Caroline Gauchotte Lindsay (University of Glasgow)

Low eV GCxGC-ToF MS or some new aspect of sample prep for environmental samples

Dr Laura McGregor (SepSolve Analytical Ltd.)

Exploring the advantages of automated sample preparation and GC-ToF for SVOC and pesticide analysis in environmental waters

Dr John Quick (ALS Environmental Ltd.)

GCxGC-ToF for remote monitoring – Cape Verde Atmospheric Observatory (CVAO)

Dr Katie Read (University of York)

Dr Emma Schymanski (University of Luxembourg)

Committee:

Dr Roger Reeve (Environmental Chemistry Group)  

Prof. Graham Mill (University of Portsmouth)

Dr Lee Williams (University of Sunderland)

___________________________________________________________

Registration information:

Standard Registration deadline: 19th February 2019

Members £90.00 (and of BMSS or Chromatographic Society, discount code needed)

Non-members £120.00

Students RSC members, retired members and unwaged (discount code needed) £25.00, Students, non-members £35.00

Discount codes:

BMS and Chromatographic Society members 19BMC14

Retired/ unwaged 19RU22

Register here on the Royal Society of Chemistry’s Conference and Events database 

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Emerging Investigator Series – Lin Du

Lin Du is a Professor of Environmental Sciences at the Environment Research Institute at Shandong University. He got his PhD in 2008 at the Institute of Chemistry, Chinese Academy of Sciences, and then he worked as postdoctoral fellow at University of Leuven in Belgium. In 2010, he moved to University of Copenhagen in Denmark and worked as postdoctoral researcher until 2013. He then took an assistant professor position at University of Copenhagen. In 2014, he was awarded the national 1000-plan talents program and joined Shandong University as a professor. His current research interest is environmental surface chemistry, and his group works with experimental tools to explain the surface reaction mechanisms at the molecular level. He has published more than 80 internationally refereed papers.

Read his Emerging Investigator article “Exploring the surface properties of aqueous aerosols coated with mixed surfactantsand read more about him in the interview below: 

Your recent Emerging Investigator Series paper focuses on surface properties of mixed surfactants coated aqueous aerosols. How has your research evolved from your first article to this most recent article?

I worked on atmospheric gas phase reactions kinetics when I stepped into science as a PhD student at Institute of Chemistry, Chinese Academy of Sciences. My first few articles focused on ozone reaction kinetics and thereafter, through the experience of radical kinetics and infrared spectroscopy studies of the reactions and interactions of the volatile organic compounds in the atmospheric environment, I moved my research interest into environmental surface chemistry after I joined Shandong University. It has been quite straightforward to come from gas phase research and go for heterogeneous study, since both happens in the same environment. This newest paper published in ESPI shows a nice representative work of my surface study.

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

It is very exciting to observe a single layer of molecules at the air-water interface, and more importantly, the strong and weak interactions between the molecules could also be monitored.

In your opinion, what are the most important unanswered questions about understanding air-sea exchange?

Huge amount of bubbles in the sea water bring a lot of substances into the atmosphere and the aerosol particles could also “drop” into the sea. However, different chemical composition exhibits different feature in the transferring processes. To make these processes clear at the molecular level and to “sum-up” the effects caused by these transferring at a global scale, would be one of the most important questions to solve for the air-sea exchange.

What do you find most challenging about your research?

I would say that, the challenging part for research is to find more tools to complement what we have observed with our techniques. It would be great if more collaboration with the right techniques can promote the understanding of processes occurring at the aerosol surfaces.

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

Currently, as a member of the local organization committee and one of the conveners of the “Smog chamber and the related lab studies” Session, I am actively involved in the 24th National Conference of Atmospheric Environment in China, which will be held on Nov. 2-4, 2018, at Qingdao. The conference is definitely a nice place where we can meet. If you cannot catch this soon-to-come conference, I will also show up at the 11th Asian Aerosol Conference (AAC) in Hong Kong, May 27-30, 2019.

How do you spend your spare time?

Spending time with my family is always on the top of my wish list. Sometimes I travel with my 9-year-old son to visit different cities, and I enjoy very much this kind of father-and-son-only trip. Staying at home and taking care of my 9-month-old daughter is also something I enjoy as a father since the day she was born. Bringing my wife to a nice restaurant and having a memorable dinner is also my favorite.

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

I would choose to be a diplomat. I feel as a diplomat, one can bring benefits to general public and a country. Just as a scientist, we spend great efforts to create and spread the knowledge, to let the public all benefit.

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

There are so many things to learn as an early career scientist, however there is no text book showing exactly what and how to learn. My advice is to communicate with others including early career scientists, and also senior established scientists. They might not give you the direct answers to your questions, but they definitely can bring you new ideas and help you. This advice is valid for hands-on research, career development, soft skills, and so on.

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Canadian Ecotoxicity Workshop – Poster Prize Winner!

We are delighted to announce the winner of the Canadian Ecotoxicity Workshop that took place in Vancouver from 30th September – 3rd October 2018. The best poster was awarded to Jordana Van Geest of Golder Associates with her poster title: “A sulfite and total dissolved solids (TDS) toxicity interaction study for coal mine influenced waters in British Columbia.” The award was presented by Curtis Eickhoff at the annual general meeting luncheon that took place on Wednesday 3rd October.

On behalf of the Royal Society of Chemistry, we would like to congratulate Jordana on this outstanding achievement.

Poster prize winner at Canadian Ecotoxicity Workshop 2018: Jordana Van Geest

 

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Emerging Investigator Series: Annika Jahnke

Credit: Sebastian Wiedling/UFZ

Dr Annika Jahnke did her PhD in Environmental Chemistry at the Institute for Coastal Research at the Helmholtz Centre Geesthacht and Lüneburg University. She worked at the Department of Applied Environmental Science at Stockholm University as a postdoctoral fellow and research fellow for 7 years before she returned to Germany as a research group leader and deputy head of the Department Cell Toxicology at Helmholtz Centre for Environmental Research – UFZ in Leipzig. Annika’s current research focus lies on the development and application of novel methods based on silicone “Chemometers” in multimedia environments, combined with advanced chemical analysis and bioanalytical profiling of the sampled mixtures of pollutants. Her main goal is to study chemical activities in order to describe processes such as bioaccumulation in the aquatic environment, internal exposure and effects in marine mammals and human exposure (CHEMO-RISK project). Additionally, the impacts of environmental weathering on the transport, fate and effects of microplastic in the marine environment (WEATHER-MIC project) is in Annika’s focus.

Read Annika’s Emerging Investigator article “Effect-based characterization of mixtures of environmental pollutants in diverse sediments” and read more about her in the interview below:

Your recent Emerging Investigator Series paper focuses on effect-based characterization of mixtures of environmental pollutants in diverse sediments. How has your research evolved from your first article to this most recent article?

My first article was based on my Diploma thesis that investigated alkylphenols in the effluent of a large sewage treatment plant. Since this study, I have focused on very different research areas during my PhD (patterns of polyfluorinated compounds in the coastal atmosphere) and my time as a postdoc and research fellow (development of silicone-based Chemometers to assess aquatic bioaccumulation). Another new aspect has been microplastic-related research. I recently broadened my expertise further by including effect-based tools in addition to chemical analysis, and this paper is the first product of this novel research theme at the department Cell Toxicology at UFZ.

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

I particularly like the breadth that I am able to cover right now thanks to a grant that allowed me to take a step further from doing all experiments myself to extending my group quite a bit. This project allows us to work on different aspects of the ”Chemometer” in parallel and to achieve substantial advancements in a reasonable time frame. While extending studies that I initiated in the past, we can also move on to new research questions.

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

The Chemometer can be very versatile, but it is also subject to substantial methodological challenges that we need to overcome before we can answer a large range of research questions. These questions include the thermodynamics of bioaccumulation in aquatic ecosystems, internal exposure and effects within organisms and the extension to assessing human exposure. We want to cover both advanced chemical analysis and bioanalytical profiling to characterize realistic environmental mixtures of chemicals and provide a scientific basis for improved management of chemicals.

What do you find most challenging about your research?

We currently face a lot of methodological challenges, but addressing them in a team makes it much easier to cope with them and overcome them. It can be challenging to collaborate in very interdisciplinary teams, but the opportunity of learning from each other is great, and it also helps to hone your communication skills and present your work in a way that is better suited for a broad audience.

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

I usually attend the SETAC annual meetings in Europe (sometimes in North America, too), but next year I will have to skip the Helsinki meeting because of a research cruise on the German research vessel SONNE to study microplastic in the North Pacific Ocean.

How do you spend your spare time?

I have two wonderful sons that I like to spend my time with. We like outdoor and sports activities, enjoy good food and interacting with people, so we are always on the go.

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

I believe in the power of images and that they can tell more than a thousand words. Hence I think right now I would choose to start a small company offering the design of science graphics, which would provide an opportunity of still being involved in science. At high school I thought being an interpreter would be interesting, but I liked natural sciences too, in particular interdisciplinary studies, so environmental science with a focus on environmental chemistry was the perfect match for me.

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

I think an important aspect is to embrace change and take the opportunity of learning novel skills, exploring new work environments and extending your expertise all the time. Working in an interdisciplinary field is the perfect setting since you always work with experts in different fields from your own, and then you should not feel ashamed of asking seemingly stupid questions to maximize interactions and synergies!

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Oxidative demethylation: biotic or abiotic methylmercury degradation?

Written by Rachele Ossola

Heavy metals are toxic, but sometimes their organometallic compounds are worse. In this respect, methylmercury (MeHg+) represents an excellent example: the detrimental health and environmental effects associated with mercury (Hg) pollution are in fact caused by MeHg+, and not by the metal itself. Methylmercury is produced in the aquatic environment by archea and anoxic bacteria, which use inorganic mercury as a starting substrate. Once produced, MeHg+ enters the food-web and accumulates in organisms such as fish and seafood, which represents the main methylmercury exposure pathway for the human beings.

Due to its high neurotoxicity, many efforts have been devoted to improve our knowledge on the environmental fate of methylmercury. In this context, identify and characterize MeHg+ degradation mechanisms represent an important step, as the degradation processes will directly affect methylmercury concentrations in the environment, thus the dose at which we are exposed.

So far, four different MeHg+ degradation pathways have been identified. The so-called oxidative demethylation involves the degradation of MeHg+ to inorganic mercury and carbon dioxide by anaerobic bacteria. Differently from the other three processes, which are relatively well understood, many doubts still remain on the details of this pathway despite almost 30 years of scientific investigations. So many, in fact, to bring some researchers back to the literature with a big question to be answered: is oxidative demethylation a real process, or it is just an experimental artifact?

Based on the available literature on methylmercury chemistry and biogeochemistry, Kanzler et al. hypothesized that a simple abiotic process could be responsible for the MeHg+ degradation that have been observed in the presence of sulfate-reducing bacteria, the microorganisms that are believed to perform oxidative demethylation. The proposed reaction involves the formation of a binuclear complex, bis(methylmercury) sulphide ((MeHg)2S), which can degrade to insoluble cinnabar (HgS) and dimethylmercury (Me2Hg), a volatile compound.

2MeHg+ + HS ⇌ (MeHg)2 S + H+→ Me2Hg + HgS

Several factors influence the thermodynamics and the kinetics of this reaction, including the solution pH and the concentrations of the two precursors, methylmercury and hydrogen sulfide. Using a combination of experimental and computational approaches, Kanzler et al. developed a model that allows the prediction of both MeHg+ speciation (i.e., the position of the first equilibrium) and dimethylmercury formation rates as a function of the chemical composition of the medium.

Based on this model, the authors showed that the binuclear complex bis(methylmercury) sulphide is the dominant methylmercury species in the pure culture studies that previously investigated the oxidative demethylation pathway. In other words, the methylmercury loss was most likely associated to the abiotic formation of (MeHg)2S, rather than to an enzymatic degradation process. Notably, these former microbiological studies lack abiotic control experiments that might undoubtedly prove or disprove Kanzler’s conclusions.

The model was also employed to investigate whether (MeHg)2S decomposition might be a relevant dimethylmercury (Me2Hg) formation pathway in the natural environment. Dimethylmercury represents almost half of the total mercury species in the open ocean, but so far very few explanations have been proposed regarding its formation mechanism. Despite being an appealing hypothesis, very slow Me2Hg formation rates were anticipated in environmentally-relevant conditions, implying that (MeHg)2S decomposition can be a relevant dimethylmercury formation process only in environments with long MeHg+ residence times, i.e. in the subsurface ocean.

In this study, Kanzler et al. cast new lights on aspects of the biogeochemical cycle of MeHg+ that are still poorly understood. New work is now needed to confirm the model’s prediction and to update our knowledge on the environmental fate of this neurotoxic compound.

To download the full article for free* click the link below:

Emerging investigator series: methylmercury speciation and dimethylmercury production in sulfidic solutions
Charlotte R. Kanzler, Peng Lian, Emma Leverich Trainer, Xiaoxuan Yang, Niranjan Govind, Jerry M. Parks and Andrew M. Graham
Environ. Sci. Process. Impacts, 2018, 20, 584–594
DOI: 10.1039/C7EM00533D

 


 

About the Webwriter:

Rachele Ossola is a PhD student in the Environmental Chemistry group at ETH Zurich. Her research focuses on photochemistry of dissolved organic matter in the natural environment.

 


*Free to read until 31st August 2018

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Fall ACS Symposium: Emerging Investigators in Environmental Science

We are delighted to announce a session taking place at the 256th ACS National Meeting & Exposition in Boston titled “Showcasing Emerging Investigators: A Symposium by the RSC Environmental Science Journals”. The session is presided over by the Editors-in-Chief for the Royal Society of Chemistry’s Environmental Science journals, Kris McNeill (ESPI), Peter Vikesland (ES Nano) and David Cwiertny (ESWRT). We warmly invite you to join us on 20th August for this exciting Symposium.

The Symposium will feature talks from six early career environmental scientists who have been featured as Emerging Investigators in either Environmental Science: Processes & Impacts, Environmental Science: Nano or Environmental Science: Water Research & Technology. The work that they will present at this event showcases the high-quality, cutting-edge research being conducted by the early-career members of our community.

Symposium details:

When: Monday 20th August, 1:00 PM

Where: Room 259A, Boston Convention & Exhibition Center

Speakers and Talk titles:

Stacey Louie University of Houston, USA

Formation and effects of heterogeneous protein-humic surface coatings on nanoparticles

Reginald Rogers Rochester Institute of Technology, USA

Using carbon nanomaterials to address the grand challenge of clean water for all people

Cora Young York University, Canada

Understanding long-range transport of perfluoroalkyl substances and flame retardants

Anke Neumann Newcastle University, UK

Reactions at the Fe mineral-water interface: Impact on contaminant fate

Nicole Fahrenfeld Rutgers University, USA

Viability and ecology-based tools to improve hazard characterization for environmental antibiotic resistance

Ameet Pinto Northeastern University, USA

Who, where, and why of the drinking water microbiome

            Find out more           

This Symposium complements the growing Emerging Investigators Series of papers published by each of the Environmental Science journals, as well as the broader mission of the RSC to support researchers in the early stages of their careers. Through the Emerging Investigator Series initiative, the journals provide a unique platform for early-career environmental scientists & engineers to showcase their work to the broadest possible audience. More details about the Emerging Investigators Series for each of the journals can be found at rsc.li/emerging-series

In addition, look out for Executive Editor Simon Neil during the event. You can meet him at the symposium or throughout the conference at the RSC stand (number 2008)

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Emerging Investigator Series – Ryan Sullivan

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.

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Emerging Investigator Series – Ning Dai

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.

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