Environmental Science: Processes & Impacts blog

Dr. Zhenyu Tian (he/him) is an environmental chemist curious about organic pollutants in the environment. He received his Ph.D. from the University of North Carolina, where he studied the transformation products and co-occurring pollutants of PAHs in contaminated soil. Then he worked as a postdoctoral research scientist at the Center for Urban Waters, University of Washington Tacoma, applying non-target screening to identify emerging contaminants in water and biota and to evaluate engineered treatment systems. With the research group, he identified 6PPD-quinone, a ubiquitous tire rubber chemical that kills coho salmon via urban stormwater. Dr. Tian is an Assistant Professor in the Department of Chemistry and Chemical Biology. He is also affiliated with the Department of Marine and Environmental Sciences and the Barnett Institute for Chemical and Biological Analysis.

Read Zhenyu’s Emerging Investigator Series article “In-depth chemical profiling of tire and artificial turf crumb rubber: aging, transformation products and transport pathways” and read more about him in the interview below:

Your recent Emerging Investigator Series paper focuses on chemical profiling of crumb rubber in tire and artificial turf at different ages. This is not the first time you’ve published in ESPI! You’ve previous coauthored papers on the complexity of contaminants mobilized from storms, characteristics of the ubiquitous transformation that you discovered – 6PPD-quinone, and you even co-edited a special issue on complex chemical mixtures . How has your research evolved from your first article to this most recent article?

I would say those earlier publications reflected a slight shift and expanding of research topics. The San Francisco Bay stormwater paper summarized a multi-year, multi-group project that dates back to 2018 and the samples provide support for stormwater as a source of high concentrations of tire-rubber related chemicals. With the discovery of 6PPD-quinone as the toxicant related to coho salmon mortality, we then did experiments to figure out its properties, like solubility, octanol-water partition coefficient, and sorption to common container materials. Now, at Northeastern University, the focus of my group is chemical contaminants from end-of-life tires, which is the subject of this new paper. Here, we discuss the aging and transformation of crumb rubber in artificial turf fields.

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

Working with students is probably one of the most exciting things. Both graduate students and undergrads at this university are outstanding. Also, the atmosphere really encourages interdisciplinary collaboration, which is great.

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

In the realm of environmental chemistry, there are numerous unanswered questions on organic pollutants. While my perspective represents only a small part of the larger picture, I am particularly intrigued by the question: “What contaminants have the most significant impact under real environmental conditions?”. The focus on identifying the most impactful contaminants is crucial because we face an overwhelming number of organic pollutants, which is impractical to test, remediate and ban. Simultaneously, we recognize that many human diseases and ecological issues are likely linked to these contaminants. The challenge lies in bridging the gap between these two realities – identifying which specific pollutants are responsible for these problems.

What do you find most challenging about your research?

Oof, a lot of challenges! For now, I am mostly troubled by 1) getting more grants to support my projects, both ongoing or in mind and 2) finding collaborators in toxicology. Consider this an open call: Dear toxicologists in the Greater Boston Area and the northeastern United States, let’s discuss and collaborate!

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

Dr. Imma Ferrer from the University of Colorado Boulder and I will be hosting an invited symposium on Innovations and Future Directions in Environmental Non-Targeted Analysis at PittCon 2025, which is a conference on analytical chemistry, in Boston from March 1-5. We have lined up four great speakers. See you there!

How do you spend your spare time?

I spend time with my family and my dog. I used to have some time for sports and games, but less so now.

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

I want to work on many things but I doubt a profession is realistically achievable these days. Maybe a hunter? Archaeologist? Paleontologist?

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

Wow, this is a hard one as I am still struggling as an early career scientist. As such, this is not advice and maybe not even wisdom, but more of an opinion: I see myself/my career as an experiment. We make hypotheses and we put in effort that we think are correct and then see if it all works. If not, we acknowledge it’s a negative result. If someday I am not working as a scientist, that means my experiment didn’t end up working.

Laurel ThomasArrigo is a professor of Environmental Chemistry at the University of Neuchâtel. Prof ThomasArrigo’s research links a/biotic molecular- and micro-scale processes to physical changes at the catchment-scale to study biogeochemical cycling of nutrients and elements in the context of climate change. She combines advanced spectroscopic techniques and analytical chemistry with model laboratory and field-based studies. Prof ThomasArrigo holds a BSc in Mathematics and History from the University of Colorado (USA) and worked as an environmental consultant before obtaining her MSc in Hydrogeology at the University of Goettingen (Germany), and then PhD from ETH in Soil Chemistry in 2017. In 2023, Dr. ThomasArrigo joined the Institute of Chemistry at the University of Neuchâtel in Switzerland where she formed the Environmental Chemistry group.

Read Laurel’s Emerging Investigator Series article “Coprecipitation with glucuronic acid limits reductive dissolution and transformation of ferrihydrite in an anoxic soil” and read more about her in the interview below:

Your recent Emerging Investigator Series paper focuses on the reductive dissolution and transformation of native Fe minerals in anoxic soil using stable iron isotopes. In fact you’ve published 5 other articles in our journal on ferrihydrite transformations in ESPI. How has your research evolved from your earliest work to this most recent article?

Ferrihydrite is a common iron mineral found in wetlands. It is often associated with trace elements like arsenic, which is what I initially studied during my PhD. Specifically, in places like wetlands, where the water-table fluctuates, transformation of ferrihydrite can lead to the release of sorbed arsenic. In these early studies, we also found that if organic carbon was present, it impacted the extent of ferrihydrite transformation. This finding sparked my interest in iron and carbon interactions. Over the years, I studied iron mineral transformations in both natural and synthetic samples and in field- as well as controlled lab-experiments. A continual challenge has been how to interpret and relate results across these different spatial and experimental scales. Which brings me to my most recent work. By using stable iron isotopes, we combine mechanistic information on mineral transformation with the complexity of working in a natural soil; a step towards bridging the gap between lab- and field-experimental results.

Laurel, I have to ask you how you write your name because I’ve seen it two different ways. Is it Laurel Thomas Arrigo or Laurel ThomasArrigo?

My last name is ThomasArrigo (no space).

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

I’m really excited about combining lab- and field-based research. For example, one of my current projects explores the role of iron minerals for carbon cycling in Icelandic wetlands. In addition to field campaigns, where we have little control over environmental conditions, we conduct controlled experiments with the collected soils in the lab. Comparing the results helps us understand how various aspects of changing environmental conditions impact coupled element cycling in soils.

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

One of the most important questions in environmental biogeochemistry is how nutrient and element cycles respond to changing environmental conditions. Soils play a big role in facilitating nutrient and element cycles, and there is a lot great work studying how soil components, including mineral phases, impact biogeochemical cycles. Still, there are many unanswered questions that currently limit our ability to accurately predict future element cycles; a key requisite to developing sustainable solutions to pressing environmental concerns.

What do you find most challenging about your research?

A challenge to many environmental science research questions is how to translate results across scales; both experimental scales; from simple to complex systems, but also spatial scales; from the lab to the field. Constantly trying to bridge this gap and explain field-scale phenomenon through mechanistic results obtained in lab studies can be trying, but it leads to diverse and exciting research with many unanswered questions.

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

I generally go to the Goldschmidt Conference, which is an international meeting on geochemistry jointly administered by the Geochemical Society and the European Association of Geochemistry but haven’t planned the rest of 2025 yet.

How do you spend your spare time?

I go to the mountains as often as I can. Climbing, hiking, skiing, or mountain biking; really anything that gets me outside and moving.

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

I always enjoyed sports and have great respect for physical therapists who kept me active after various injuries. So, sports therapy would be an interesting career!

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

Start building a network, both of peers and mentors. Peers create a great support system to get through challenging times and may turn into colleagues or collaborators in the future. Mentors can offer advice, open doors, and facilitate further introductions. Invest time to attend conferences and scientific talks and keep in touch with the contacts you make.

Prachi Joshi is a Junior Group Leader in Geomicrobiology at the University of Tübingen in Germany. Dr. Joshi’s research focuses on redox processes that impact environmental issues including climate change and pollution. In particular, Dr. Joshi studies the biogeochemistry of carbon and iron. Dr. Joshi has extensive expertise in molecular, bench scale, and field techniques to probe organic matter and iron minerals to provide mechanistic understanding with links to large scale phenomena. Dr. Joshi has a B.Tech in Chemical Engineering from the University of Pune in India, M.S. and Ph.D. in Environmental Engineering from Pennsylvania State University, USA. After spending 2 years as a postdoctoral fellow in environmental chemistry at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, Dr. Prachi joined the University of Tübingen in the Department of Geosciences in 2020.

Read Prachi’s Emerging Investigator Series article “Preferential adsorption and coprecipitation of permafrost organic matter with poorly crystalline iron minerals” and read more about her in the interview below:

Your recent Emerging Investigator Series paper focuses on Fe–OC associations formed by coprecipitation and adsorption using tests you performed on field-collected palsa, bog, and fen soils. How has your research evolved from your first article to this most recent article?

It has been quite a journey from my first paper looking at the stability of goethite, a crystalline Fe(III) oxyhydroxide, to the current work in permafrost systems. When I first started my graduate research, I was driven by understanding water quality in aquifers (I’m an engineer by training). Along the way, I discovered that I was passionate about fundamental questions and enjoyed delving into the ‘why’ and ‘how’ of environmental chemical phenomena. This has led me to diverse projects such as mineral recrystallization, organic matter redox chemistry, and carbon cycling in wetland systems. Over time, I decided to expand from working in the laboratory alone to investigating classical processes in the environment. This brings me to the most recent paper that looks at association between minerals and organic carbon in thawing permafrost systems.

Dr. Joshi, like many of our emerging investigators, you’ve travelled a lot for your scientific career. Moving between continents can be daunting! How has your global experience impacted your perspective?

I’ve always thought of international mobility as one of the most exciting parts of science. Although it can be intimidating at first, I found that experiencing new cultures, both inside the laboratory and outside in a new city or country, has been enriching. Each move has brought new scientific perspectives; for example, moving to the Environmental Chemistry group at ETH Zürich brought me into contact with researchers with expertise ranging from mass spectrometry to methane release. I’ve also been fortunate to have welcoming and supportive research environments wherever I’ve moved.

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

I’m particularly excited about bringing the concepts that we teach in our courses out into field-based research and studying them in all their complexity. For example, one of my current projects looks at carbon cycling in coastal wetlands at the northern coast of Germany, where we combine knowledge from chemistry, microbiology, soil science, and hydrology. I even had to learn quite a bit about plants in that project.

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

One of the most important questions that environmental scientists have been chasing has been: how can we predict the release of greenhouse gases from natural systems? There is a lot of excellent work going on in this field; however, we still have a long way to go. The answer to this question is key to accurate global carbon cycling models which, in turn, guide our prediction of future climate scenarios and the development of mitigation strategies.

What do you find most challenging about your research?

The big questions in the field of environmental redox chemistry require interdisciplinary effort; bringing the right people together and speaking the same language represents a big challenge. We sometimes find that the research questions we have, posed somewhat differently, have been investigated by scientists from a different field such as materials chemistry. We should take advantage of this existing expertise and collaborate more!

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

I generally go to the American Chemical Society meetings or the Goldschmidt conference. I still have to plan for 2025 though.

How do you spend your spare time?

Fortunately, I’ve always lived in places that have good access to nature, so I enjoy running and hiking. I also enjoy reading (non-scientific) books and cooking.

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

As a young person, I faced the choice between computer science or chemistry and chose the latter. So, in an alternate life, I would likely be a computer scientist or developer. If I had to choose now though, I would probably delve into the field of environmental economics as I find it fascinating and extremely relevant for the future.

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

Connections are incredibly important – the friends I made in graduate school and during my postdoc are also my collaborators today. It’s worth investing the time to nurture these connections by going to conferences, organizing scientific visits, and keeping in touch over the years. Related to this, I recommend keeping an open mind; you never know when a chance conversation during a coffee break at a meeting turns into a great project idea.

Vaughn Mangal is an Assistant Professor of Chemistry at Brock University in St Catharines, Ontario, Canada. Vaughn graduated in biochemistry and molecular biology in 2013 from Trent University in Canada where he remained for his PhD in environmental science under the supervision of Drs. Celine Gueguen and Alexandre Poulain. During his PhD, he received an NSERC postgraduate scholarship and the W. Garfield Weston Scholarship for his research on contaminant transport in northern aquatic ecosystems. During his PhD, he also patented 2 technologies that use algae to remediate metals from contaminated water sources. After graduating with his PhD in 2019, Vaughn was an NSERC postdoctoral fellow with Dr. Carl Mitchell at the University of Toronto Scarborough for two years. Vaughn uses his background in biochemistry and environmental science coupled with training in mass spectrometry to study the molecular biogeochemistry of organic matter and its implications for contaminant transport.  Since July 2022, Vaughn has established an active research program with field and lab components, looking at relationships between contaminant transport, human disturbances, and organic matter. At Brock, Vaughn teaches analytical chemistry, environmental chemistry, and quantitative chemical analysis courses.

Read Vaughn’s Emerging Investigator Series article “Impacts of land use on dissolved organic matter quality in agricultural watersheds: a molecular perspective” and read more about him in the interview below:

Your Emerging Investigator Series paper uses ultra high resolution mass spectrometry to study the molecular composition of dissolved organic matter (DOM) in agricultural watersheds to better understand land use impacts. I see that you also recently published another paper in ESPI on DOM in Canadian boreal forest streams. Thank you for choosing our journal! How did your research evolve from your very first publication to your more recent articles?

During my graduate studies, I had the opportunity to develop my interest in analytical chemistry and explore new strategies for solving environmental questions about organic carbon and contaminants. I published my first first-authored publication during the early years of my PhD in 2015 at Trent University, where I used a combination of fluorescent tagging and field flow fractionation to simultaneously separate, identify, and quantify sulphur species released from algae and sulphur-containing molecules in Canadian sub-arctic watersheds. I continued researching how contaminants are mobilized during the spring thaw of these large watersheds in northern Canada. My experience in biochemistry and molecular biology also allowed for a deeper investigation of how microorganisms like bacteria and algae respond to contaminant exposure and the implications for how microorganisms uptake metals like mercury and cadmium with increasing human disturbances. During my postdoctoral studies at the University of Toronto, I became very interested in the effects of forest harvesting on mercury biogeochemistry in Canadian forests and how industries can help refine their management practices to reduce mercury transport. My recent contributions build on my PhD research by focusing on how environmental factors influence the molecular properties of dissolved organic carbon and the implications of these changes on contaminant transport.

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

Since starting my research program at Brock University in 2022, I am very excited to help inspire the next generation of environmental chemists. I am also excited to work with collaborators to help refine management strategies to reduce contaminant transport in Lake Erie watersheds. It’s very promising to see a shift across industries towards achieving more sustainable practices informed by environmental research.

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

One of the most important research questions is how plastic compounds are changing the natural biogeochemical cycles of carbon in aquatic systems. Not only can microorganisms use decomposed plastics as nutrient sources, but these plastics further complicate the fate and transport of other organic and inorganic contaminants. Developing methods to simultaneously characterize organic carbon and carbon derived from plastic pollution will be key to better understanding these interconnected biogeochemical cycles.

What do you find most challenging about your research?

One of the most challenging questions is how we translate small-scale processes and mechanisms into practical solutions and applications. Designing new analytical workflows and developing new ways to characterize organic carbon and contaminant transport is useful, but relating these mechanisms to complex ecosystems where not all variables can often be controlled is challenging.

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

I will be attending the International Conference for Analytical Sciences and Spectroscopy this year, and plan on attending conferences like the Canadian Geophysical Union (CGU), Canadian Chemistry Conference and Exhibition (CCCE), and Metabolomics 2025.

How do you spend your spare time?

I like spending time with my kids, running, and going for hikes in my spare time. I also enjoy gardening and playing soccer.

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

If I weren’t a scientist, I would have pursued a career in paramedics or physical therapy.

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

My advice would be that it’s never too soon to establish your own independent network of collaborators or colleagues. Work on building and maintaining relationships with other academics at conferences or with other labs, as communicating and collaborating with other scientists leads to new ideas. I’d also recommend working on scientific communication skills as effectively communicating your research to non-specialists is extremely important.

Theo is an Assistant Professor in the School of Energy and Environment at City University of Hong Kong. Her current research uses a combination of laboratory experiments and field observations to investigate the impacts of air pollution policies and climate change on the multiphase atmospheric chemistry of aqueous droplets and the formation and transformation processes of organic aerosols. Theo completed her undergraduate studies in Chemistry and Mathematics at the University of Toronto. She went on to complete Ph.D. studies in Physical Chemistry under the supervision of Prof. Stephen Leone and Dr. Kevin Wilson at the University of California, Berkeley. Her Ph.D. research focused on investigating fundamental reaction mechanisms that govern the heterogeneous photooxidation of organic aerosols. She then went on to complete postdoctoral studies at Georgia Institute of Technology under the supervision of Prof. Sally Ng and Prof. Rodney Weber. There, she performed laboratory chamber studies to investigate biogenic secondary organic aerosol formation mechanisms and participated in field studies to investigate the effect of ammonia on aerosol composition and acidity.

Read Theodora’s Emerging Investigator Series article “Aqueous photooxidation of live bacteria with hydroxyl radicals under clouds-like conditions: Insights into the production and transformation of biological and organic matter originating from bioaerosols” and read more about her in the interview below:

Your recent Emerging Investigator Series paper focuses on Aqueous photooxidation of live bacteria with hydroxyl radicals under clouds-like conditions: Insights into the production and transformation of biological and organic matter originating from bioaerosols. How has your research evolved from your first article to this most recent article?

My Ph.D. studies focused on the heterogeneous photooxidation of organic aerosols. My first lead-author publication (Nah et al., Anal. Chem. 2013) was on the application of Direct Analysis in Real Time Mass Spectrometry (DART-MS) in the real-time in situ chemical characterization of submicron organic aerosols. It demonstrated how we can use surface sensitive mass spectrometric tools to probe real-time changes in the chemical composition of the surface of submicron organic aerosols during heterogenous photooxidation. I have continued my research on atmospheric aerosol chemistry. However, my research interests have expanded even further to include the atmospheric chemistry of bioaerosols under different environmental conditions. In this most recent article, my group investigated what happens when live bacteria interact with hydroxyl radicals in clouds during the daytime. It builds on our previous work (Liu et al., Atm. Chem. Phys. 2023) which investigated the effects of pH and light exposure on the survival of bacteria and their ability to biodegrade organic compounds in clouds.

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

I have found this research area (i.e., atmospheric chemistry of bioaerosols) to be both exciting and challenging because I do not have a background in microbiology. In fact, I have not taken a single biology class in my entire life! I spent a lot of time during the COVID-19 lockdown learning about bacteria. I am lucky that I was able to establish a research collaboration with a microbiologist in my department who is interested in atmospheric bioaerosols. Our ongoing research collaboration has been fruitful and we have been able to leverage one another’s expertise to ask and answer interesting research questions on bioaerosols. In addition to investigating the atmospheric chemistry of bioaerosols in outdoor atmospheres, we have been investigating what happens when airborne bioaerosols and microorganisms adhered on surfaces interact with atmospheric oxidants and chemical compounds in the indoor built environment. Stay tuned for more of our work!

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

At present, little is known about what happens when live microorganisms such as bacteria interact with atmospheric oxidants and chemical compounds in the outdoor and indoor atmospheres under different environmental conditions. These multiphasic interactions potentially have important implications for atmospheric processes, air quality, and human health. There are so many questions that still need to be asked and answered in order for us to gain a basic understanding of these interactions before we can even consider their implications. Asking and answering these questions will require the expertise of both atmospheric chemists and microbiologists.

What do you find most challenging about your research?

Communicating my research to people with different backgrounds and levels of expertise. A lot of my research use laboratory experiments to investigate fundamental reaction mechanisms and understand how things work at the molecular level. Sometimes, I find it challenging to convince others, especially those not in the atmospheric chemistry field, on the importance and relevance of my research approach to solve “real world” air pollution issues.

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

I will be presenting my work at the 9^th International Conference on Fog, Fog Collection, and Dew in Colorado in late July, and at the 2023 Atmospheric Chemistry Gordon Research Conference in Maine in early August.

How do you spend your spare time?

I spend most of my spare time watching travel documentaries to unwind. Recently, I have been spending some of my spare time learning Mandarin so that I can communicate more effectively with my Chinese collaborators.

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

If I were not a scientist, I would still want do something related to the environment. I could see myself working for an NGO involved in environment management and conservation work.

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

I have been fortunate to have encountered many amazing mentors who have been generous with their time and advice. I will share the same piece of advice that one of my mentors gave me when I was deciding on where to attend graduate school: You need to embrace change and be willing to step outside of your comfort zone. I find that this piece of advice can be applied to career development, research, and so on. I have relied on this advice at various points of my career, including when I decided to move to a new country to start my independent research career, and when I pursued opportunities for multi-disciplinary collaborations to work on interesting research questions.