20-minute listen/watch | 13-minute read
Microplastics are turning up in unexpected places, including tidal freshwater marshes. Researchers are uncovering how these ecosystems trap plastics before they reach the ocean, leading to long-term accumulation in sediments and habitats. Understanding where plastics accumulate and how different materials behave matters for protecting ecosystems, communities, and long-term environmental health.
Transcript
Raymond Najjar
On some level, the marshes are doing a service by preventing the plastics from getting out into the ocean. But the marshes themselves are very important and productive environments. They're important habitat for all kinds of fauna. So they're being exposed now to these microplastics.
Host
Welcome to Growing Impact, a podcast by the Institute of Energy and the Environment at Penn State. Each episode of Growing Impact explores the projects of Penn State researchers who are solving some of the world's most challenging energy and environmental issues. Each project has been funded by the Institute's Seed Grant Program that grows new research ideas into impactful energy and environmental solutions. I'm your host, Kevin Sliman.
Microplastics are everywhere. But where exactly do they end up, and what happens once they get there? In this episode of Growing Impact, three Penn State researchers take listeners into the tidal freshwater marshes of the Delaware River to investigate a hidden piece of the plastics puzzle.
Sparked by a question about missing plastics in the ocean, their research traces how different types of microplastics move through water and sediments, where they accumulate, and why tidal marshes may play an outsized role in trapping them. The conversation looks beyond headlines to explore what these findings could mean for ecosystems, environmental management, and human health, and why understanding the details matters for solving a global problem.
Hello team, welcome to Growing Impact. Thank you so much for coming on the episode and discussing your research on microplastics, the way they move through the water, where they end up. It's a really important topic. But before we dive into it, can everyone go around and do a brief introduction?
Lisa Emili
Hi, I'm Lisa Emili. I am an associate professor of physical geography and environmental studies at Penn State's Altoona campus. So I am at a primarily undergraduate campus. My research is in the fate and transport of contaminants and more recently, microplastics and nanoplastics in freshwater environments. Primarily, I work in streams and wetlands.
Raymond Najjar
Hi, my name is Ray Najjar. I'm a professor of oceanography in the Department of Meteorology and Atmospheric Science at Penn State. I'm here on the main campus, and I work on a variety of issues in oceanography and related fields. A lot of my work is in coastal waters these days. I study the cycling of carbon in coastal waters. I'm interested in how climate change affects coastal waters, and in the last five years or so, I've gotten interested in microplastics and that transport and fate of plastics and in coastal waters.
Nathaniel Warner
I'm Nathaniel Warner. I'm an associate professor in Department of Civil and Environmental Engineering, also on the main campus, focused mainly on water quality issues. A lot of the recent work on microplastics, for sure, kind of reconstructing that using some methods, looking over time. But before that, I looked at a lot of impacts from energy development. So coal, oil, gas, development and impacts on water quality from those.
Host
Can you tell me a bit about the original seed grant that this is based off of — that this conversation is based off of? It was called Transport and Fate of Microplastics in the Tidal Marsh Ecosystem, Delaware River. Can you just give a brief overview of the work that you set out to do? And just, again, high level overview of what this project was about?
Lisa Emili
We really have been on the forefront and the cutting edge of microplastics as we've been trying to do it. And so I would say what we started out saying we wanted to do was pretty straightforward. We wanted to understand. We wanted a baseline idea of how many plastics were coming into this Delaware Estuary site and what kind of plastics they were.
So it was basically how much there is and what are they. So fate and transport, you know, like are they accumulating in certain spots within this wildlife refuge, which was our study site? It started as simple as that. And the proposal was a really short proposal. It became much more complex when we actually tried to do it. And then that's where a lot of our team started to get built, because these things are sort of organic, which is kind of a not a pun exactly, but like it's also we're into organic chemistry all of a sudden.
And then it was like questions came up, oh gosh, who do we talk to to do this? Who do we know? And literally each of us leveraged as many people and networks as we could. And this one little project that started as this IEE seed grant has blossomed into so much more.
Raymond Najjar
I wanted to get involved in it, and I was fascinated by this problem of the missing plastics in the ocean, which is that there seems to be a lot more going into the ocean than is sort of floating around at the surface. And I was able to get some seed grant money before this seed grant from my College of Earth and Mineral Sciences, and was able to hire a postdoc. And I worked with some other faculty in the college.
We ended up doing a modeling study for the Chesapeake Bay, and we found that in the model, a lot of plastic was getting trapped on the shore. That was just a modeling study, which which is interesting and has some utility, but you really want to see if plastics are actually getting stuck on the shoreline in estuaries. I think we came up with the idea — so, you know, to try to find a coastal setting where we could measure the accumulation of plastics.
Host
What first drew your team to study microplastics in freshwater and tidal marsh environments, and how has your sense of the problem changed as the research progressed?
Lisa Emili
It was a result of an IEE networking event that we each had kind of, you know, lightning talks and talk quickly about what we were interested in. And Zach Nemec, who is the coastal outreach specialist for the Pennsylvania Sea Grant, reached out to me after that networking event to say, "hey, I also am interested in these microplastics, and I have a group of people who are really interested in doing like a baseline study and figuring out what the plastics are that are coming into the John Hines Wildlife Refuge at Tinicum." So, John Hines National Wildlife Refuge at Tinicum. And so that's the first connection we made and the potential of the project. And then it's managed by Fish and Wildlife, and they were absolutely fantastic working with us. And Ray and I kind of went out for a first recon trip. So that started the why we ended up in that particular area.
And then it was also following on — They wanted to see if the Philadelphia plastics ban, like for plastic bags, was going to have any impact. And so it kind of like piggybacked on that. And so, you know, we came in thinking similar to like how we were going to start the seed grant and this project was the idea of sort of a two-fold focus. And from my perspective, as like also being the field researcher and figuring out how do I collect these samples and then how do we identify them. And then, you know, where were they accumulating, how much was accumulating, and what type of plastics is sort of where we started and how I kind of, you know, got into this coastal environment, which was not something I had thought of until I really had made that connection with Ray, and then this broader group of people.
Raymond Najjar
Yeah. And the title part was key because we wanted to address the missing plastics, because we're looking at a point where we have estimates of the delivery of plastics to the ocean. That's right above the so-called tidal fresh region, right. And so the first place they could get stuck, you know, before getting out to the ocean, would be in these sort of marshes like the ones at Tinicum.
So that's sort of why we were looking at a tidal marsh and maybe even specifically a tidal fresh marsh site. Tidal pressure is also quite unique and quite interesting because they're this sort of mix of the ocean and land environment. They're ocean, because they're tidal, but they seem like terrestrial aquatic systems because they're fresh. So they're really like an interfacial system and, and quite unique.
Nathaniel Warner
Well, I was going to say, Ray, you've avoided saying the plastic paradox, but that's what got me the word, you know, or the, the phrase. I was like, oh, that's — I like solving problems. And so the idea that there's this unanswered question out there that maybe we can combine a few different expertise, get some new data that, as Lisa pointed out, hasn't really been looked at. That's just very fascinating as a scientist. Right? Like, let's try to answer that question.
Host
So that other side of it — has your sense of the problem changed as research has progressed?
Nathaniel Warner
I think for me, the problem started as talking about it simply as microplastics. And now I think it's evolved to really having to think about it as polymers and chemicals, and that they all kind of behave differently, and all plastic is not the same. So just the fact that you find small pieces of plastic is one thing. Probably for the bigger questions that you're going to lead into, it really matters what type of plastic, what type of polymer that is. And that can have a really big impact on whether we think it's a major problem for ingestion or the aquatic life, or it's not as much of a problem.
Lisa Emili
I think that for me, like the thing that has been the biggest impact to me personally, and then for where it's driving the science, is that I think that we're past the point. And most people in general know that, you know, plastics are everywhere and they're in everyone. And that is really driving, I think, where we're, you know, moving towards is really getting a better understanding of how they behave along the way, what they pick up along the way, how the chemistry of the plastics themselves and what they're interacting with, changes in particular environments, like as they're deeper down in sediments and there are different transitional zones across these coastal ecosystems. And what does that mean for potential toxicity and and the impacts for consumption of these, inadvertently.
Host
When you look back at your sediment core work in marsh sampling, what aspects of the methods or field work stand out as particularly challenging or maybe even just surprising to you?
Lisa Emili
It took six months, but then we were out there with this airboat, and not only did we collect these samples, but when we were preparing — is it the first paper Nat? I feel like — and we were kind of justifying what we were doing and why it was important. It was also that I think we were — are we still the only study in North America — we were at the time that collected those cores to that depth. Like we had the longest time record in any study in North America, and it was only a handful of studies worldwide. Most of the studies before that were collecting what we call surficial sediment, which is in the top 5 to 10cm.
We have cores that are like two meters deep. These are significant and I think like that's where Nat's expertise was absolutely crucial because we were able to get a date and a timeline, which was something that had not been done in, particularly in these environments. And so, you know, that's also really cool. We got to figure out how to do this fieldwork. And then we got some really amazing results, and we advanced the science. So to me that's just like a win-win.
Credit: Lisa Emili. All Rights Reserved.
Nathaniel Warner
There's a reason we were the first to not many people have done it before. Right. It's really challenging to get those high-quality samples, especially with time and space. And then second, it's time-consuming and really detail-oriented to get all of these samples counted for microplastics and to do a good job doing that. It's not easy.
So, Judy [Jutamas “Judy” Bussarakum, a Penn State graduate student at the time of the work], certainly the graduate student — so motivated, so detailed, really leading that and motivating. I think she'd probably not recommend this to many other students. You know, in terms of, you know, find find another method. But you, you know, all those things together, you really need a dedicated group of people who are interested in the problem. And most of the public and most people are like, oh, yeah, let's figure that out. So you have to have that motivation.
Host
In your own words, what do you see as the most important stories the data tell about how and where microplastics are accumulating and why do those patterns matter for ecosystems and for people?
Nathaniel Warner
You know, when we look at changes over time, if we match up the plastic we produce in the world, compared to the plastic that is accumulating in these sediments, they match up, right? And okay, so we're releasing more plastic to environment. Every time we make more. We're kind of, is it every 12 years or 20 years, we're doubling the amount of plastic we produce.
So we're doubling the amount of plastic that's in all of the sediment in the water and everything. I think overall that's pretty big finding is that we are accumulating a lot of plastic because we're producing a lot of plastic. We're not doing a great job of keeping it contained. And the second thing, you know, what matters is the the polymer type or the plastic type in terms of what the overall implications will be for for longer term and the chemicals associated with those polymers. Right. Some forever chemicals, for example, are absorbed to these plastics as well.
Lisa Emili
We did see an indication that there's a potential when recycling started to happen that there was like a dip in the accumulation. So I do see that there is like a path forward. I would say like so I think that at least me personally, thinking about our work and what our data showed and, you know, tracking the timeline for accumulation and kind of backtracking to potential sources, is that there is the potential to alter the course of plastic accumulation, right, both in the environment and in humans, I think.
So to me, I feel like, you know, it's it can't always be. We understand the problem is significant and the impact is huge and the potential toxicity and the hitchhiking of other pollutants... But I guess I'm looking for the glimmer of hope. Is that part of what we can do is alter the course of this accumulation.
Host
How do your findings about microplastics being trapped in freshwater sediments and tidal marshes shape the way you think about risks to local communities, wildlife and food webs now and in the future?
Raymond Najjar
On some level, like the marshes are doing a service by preventing the plastics from getting out into the ocean. But the marshes themselves are very important and productive environments. They're important habitat for all kinds of fauna, you know, so they're being exposed now to these to these microplastics. So, you know, I think that what and the implications of that we really don't appreciate. So that's like a worry for me that arises, out of the work.
Nathaniel Warner
You know, these these stories are economically important to, you know, Chesapeake Bay, Delaware Bay, a lot of fisheries, a lot of work there. So it is going to have an impact on those that you're talking about broadening impact
Host
And based on what you have learned so far, what kinds of policy changes, community actions, or engineering solutions feel most promising to you for reducing microplastic pollution and exposure?
Raymond Najjar
A lot of the problems we're seeing with plastics in the environment are due to single use plastics, which, you know, have their utility and benefits of convenience and so forth. But I think we're finding that the single use plastics have a lot of drawbacks. And we used to do things quite successfully with reuse systems, reusing bottles, reusing containers, for example.
And I think also there are — and a lot of work is happening here at Penn State. There are alternative materials that are much more sustainable. They're being developed here at Penn State and many, many other places. So in my mind, we really have to go after single use plastics and reduce them dramatically.
Host
This work brings together people from multiple disciplines and campuses. How has that interdisciplinary collaboration influenced the questions you ask and the directions you want to take next?
Lisa Emili
People are going beyond just the hydrology, water quality part of it and wanting to really know that next piece of that puzzle. And I want to know the next piece of that puzzle. And so that's what drives me to reach out to more people at Penn State, to try and bring them in, because I think you can't do — you can do individual pieces of a puzzle — but to solve the problem, we need to put all of our puzzle pieces together and see where the connections and the interactions are.
Nathaniel Warner
I like Penn State for the reasons that there are a lot of great researchers who are willing to participate in answering these questions.
Raymond Najjar
These institutions, like IEE, are really great at facilitating and encouraging that interaction. And it seems like we're rewarded for that, you know, both through these grants and encouraged by our administrators to interact. And I think they just recognize that it's a benefit to everybody when we work together and share all of our expertise with each other.
Host
Is there a silver lining or any positive light that says, you know, yeah, we're facing this, however X Is there anything in your mind that comes to mind in that area?
Raymond Najjar
For me, I always think about how things have changed with regard to air quality and water quality, particularly in this country. The improvement, like particularly in the air quality, it's spectacular. So we had good science, we had good policy. We ended up saving a lot of money and a lot of lives. Climate change, you know, plastic pollution, biodiversity loss — these are these are massive and overwhelming problems. But I think about our past successes with the Clean Air Act, with the recovery of the ozone layer. That's another another example are we have seen very dramatic improvements in water quality in many parts of the of the country and Europe also is seeing seeing these these improvements. So it's those stories that give me hope that when we work together, scientists work together, they work with policy makers, that we can solve these sort of problems.
Host
Thank you very much, Lisa, Nat, Ray. Thank you for coming on to Growing Impact. Thank you for discussing this challenge. And thank you for doing the work that you do.
Raymond Najjar
Thank you.
Lisa Emili
Thank you. Thanks for the opportunity to talk about our work.
Host
This was season six, episode three of Growing Impact. Thanks to Ray Najjar, Nat Warner, and Lisa Emili for joining me.
For a deeper look at their story, visit iee.psu.edu/podcast, where you'll find a video version of the episode, graphics, transcripts, as well as past episodes. Our communications director is Chris Komlenic, with graphic design and video production by Brenna Buck, marketing and social media by Tori Indivero, and web support by Jon Stabinger.
Join us next time as we continue our exploration of Penn State research and its growing impact. Thanks for listening.
