Environmental Science: Processes & Impacts blog

Sanne J. Smith is an assistant professor at TU Delft, The Netherlands, in the department of Water Management at the Faculty of Civil Engineering & Geosciences. Here, she leads a research program to develop, improve and understand water treatment to minimize the impact of industrial processes on the environment.  She believes a holistic approach is required for industrial water use to achieve sustainable solutions.  She obtained her Ph.D. at the Swedish University of Agricultural Sciences under the supervision of Professor Karin Wiberg. Her PhD thesis was centered on innovative treatment technologies for PFAS-contaminated water, and she mostly worked on foam fractionation and electrochemical oxidation. She has a double bachelor degree in chemistry and chemical engineering from the University of Groningen and a Master’s in water management from TU Delft.

Your recent Emerging Investigator Series paper focuses on a quantitative measure of net health benefits of treating PFAS in drinking water using granular activated carbon by examining the trade offs in reducing PFAS versus increased particulate matter emissions and climate risk. This is your first publication in ESPI! How has your research evolved from your earliest work to this most recent article at the start of your research career?

This paper represents a bit of a shift for me, since it is much more interdisciplinary than my previous publications. Throughout my under-/postgrad studies, I mostly worked on optimization problems: How can we best remove PFAS from water? My focus is on technology development, and I simply took the need for PFAS removal as a given. Throughout the final stages of my PhD, however, I started getting more interested in the ‘why’ of PFAS removal. It is extremely resource-intensive to treat PFAS in water, and I noticed that most cost-benefit evaluations ignored the secondary impacts of the treatment technologies. That is the research gap that we tried to address in the current publication, which required completely different methods than my usual work.

Although you did your PhD at the Swedish University of Agricultural Sciences in Uppsala, you previously studied in The Netherlands for your Bachelor and Masters degrees.  How does it feel to be back in The Netherlands establishing yourself as an independent research leader?

Honestly, it still feels a bit unreal. I applied to my current position with a ‘they probably won’t hire me without a postdoc but I might as well try’ mentality, so the job offer came as a big surprise. I am currently staff in the same department as where I was a masters student, so it took some time to convince everyone (including myself) that I am not a student anymore, but I am getting there!

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

I am currently supervising a PhD student who is investigating if foaming on existing wastewater treatment plants can be used to remove PFAS. If successful, this could be an extremely cheap and benign way to prevent high amounts of PFAS from entering the environment. The research topic is quite niche, I believe there are only two groups in Australia and the US working on the same idea. The student is doing a great job and it is nice to be in contact with particularly the Australian group, to share our enthusiasm and ideas. The project is industry-funded and we are already moving to full-scale tests, so it is also amazing to see real-world impact so quickly!

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

The question that we asked in this ESPI publication is definitely important: should we even always try to remove all PFAS from water? Our publication only answered a very small and specific part of that question, so more research is definitely warranted. I recently learned the term ‘temporary tolerance of presence’, which implies that it is sometimes better to simply accept that PFAS are there and focus your removal/prevention efforts elsewhere. As someone who is predominantly in the water treatment field, it is tempting to focus exclusively on the development of better technologies, but prioritizing where PFAS treatment makes most sense is maybe more impactful.

What do you find most challenging about your research?

Definitely keeping up with all developments. PFAS is such a hot topic right now, so there are publications, start-ups and projects popping up every day. It can be difficult to distinguish between what is truly promising versus what is overhyped.

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

I am currently involved in the organization of the ‘Water in Industry’ conference, an IWA conference that will be held in Delft at the end of June 2026. Abstract submission will open very soon, so please join me there! I usually attend SETAC Europe meetings as well.

How do you spend your spare time?

I play beach volleyball, which I do 3-4 times a week during summer. We live close to the beach, so it is a great way to empty my mind, enjoy the fresh air (including the PFAS in the sea spray…) and be active!

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

I would probably become a water treatment engineer in an industrial environment. It seems silly, but I love working at landfills: leachate water is extremely interesting (because it’s so dirty) and there is a lot of good you can do when treating it correctly. The flows are also quite small compared to other types of water, which means that unconventional technologies become possible.

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

I have been extremely lucky to always be part of close-knit networks, so I highly recommend everyone to befriend their colleagues. I was one of the 15 PhD students in the PERFORCE3 project, and we became very close, both personally and professionally. In my current department, there are eight assistant professors who all started around the same time, and I could not have written this ESPI publication without the two of them who are co-authors.

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.