News & Updates

2023-12-12 - Happy end-of-semester from the Hotchkiss Lab!

Thank you to all of the collaborators, mentees, and mentors who supported our research, teaching, and learning during 2023. Best wishes for a relaxing holiday season and a curiosity-filled 2024!

Erin, Emily, Katherine, Caleigh, and Carla after dinner / painting holiday decorations at Erin's house in December 2023

2023-11-15 - Emily Mulcahy receives GCC Undergraduate Research Grant

Emily Mulcahy, an undergraduate researcher in our lab mentored by Carla López Lloreda, was awarded a research grant from Virginia Tech's Global Change Center (GCC)! Emily is a senior at Virginia Tech majoring in Biological Sciences with minors in Wetland Science and Green Engineering. The GCC award will fund Emily's proposed research "assessing the role of phytoplankton on biogeochemistry in isolated wetlands" on the Delmarva peninsula in Maryland, USA. Congratulations, Emily!

News article celebrating Emily and the other 2023-4 GCC Undergraduate Research awardees

2023-10-24 - López Lloreda co-authors article on "flipped science fair"

Carla López Lloreda recently published a paper with graduate student co-authors about their experience organizing a "flipped science fair".

From the abstract: "Flipped Science Fairs put power directly into children’s hands, inviting them to judge graduate student science fair posters. At the fair, graduate students practice communicating their research to a young audience, while children have the opportunity to see themselves as valued contributors in science. Here, we present a model for a walk-in Flipped Science Fair, designed in partnership between nine Virginia Tech graduate students and the Roanoke City Public Libraries (Roanoke, VA, USA). At our event, 27 graduate students presented posters about their research, with an audience of over 250 community members. We found that hosting the Flipped Science Fair at a public library lowered barriers to entry for participants and allowed us to reach an audience further from the university. While judging posters, children learned about a wide range of leading-edge research and had meaningful interactions with diverse scientists in small-group settings. Conversely, for graduate students, this event and associated training workshops provided an opportunity to practice communicating their research to a new audience. Throughout this article, we share our experience as graduate students collaboratively conceptualizing and organizing this community-oriented Flipped Science Fair with public library partners." Congratulations, Carla and co-authors!

Citation: Lewis, Abigail S. L., Grace O’Malley, Gates K. Palissery, Amanda Hensley, Carla López Lloreda, Claudia Perez, and Emma K. Bueren. 2023. “Flipped Science Fair Invites Children to Judge Graduate Student Posters Through a University-Community Partnership.” Journal of STEM Outreach 6 (1): 1–12. 

2023-10-12 - Hotchkiss co-authors chapter in updated Wetzel's Limnology text

Erin Hotchkiss and Tonya DelSontro co-authored the updated chapter on "Organic Carbon Cycling and Ecosystem Metabolism" in the 4th Edition of Wetzel’s Limnology: Lake and River Ecosystems. It was an honor to contribute to updating a core textbook in limnology (the study of inland waters), and I hope others find the book to be a useful reference!

Citation: Hotchkiss, E.R. & T. DelSontro. 2024. Organic Carbon Cycling and Ecosystem Metabolism. Chapter 28 in: Jones, I.D. & J.P. Smol (Eds.), Wetzel’s Limnology: Lake and River Ecosystems, 4th Edition, pp 939-997. ISBN 9780128227015

2023-09-20 - Bretz leads new paper on intermittent stream biogeochemistry

Kristen Bretz, a recent PhD graduate from our lab, recently published a chapter from her dissertation work on non-perennial stream carbon (C) and oxygen dynamics in Water Resources Research. The paper was co-authored by now-graduated VT undergraduate researcher Natalie Murphy and Erin Hotchkiss

We found that:

You can read more about our findings in the open access paper here and read about our key findings (and field assistants!) from Kristen here. Congratulations, Kristen and Natalie!

Citation: Bretz, K. A., Murphy, N. N., & Hotchkiss, E. R. (2023). Carbon biogeochemistry and export governed by flow in a non-perennial stream. Water Resources Research, 59, e2022WR034004.

Figure 1 from Bretz et al. 2023. (a) A map showing our study site, Beast Stream in southwest Virginia, USA. The location of the sensor monitor site is noted with an orange star. (b) Images of the stream sensor site at different flow levels.
Figure 3 from Bretz et al. 2023 showing changes in dissolved oxygen (DO) and carbon dioxide (CO2) with stream discharge (Q), as well as the relationship between DO and CO2 in Beast Stream, VA. The points are color-ramped by date.
Figure 4 from Bretz et al. 2023 of changes in dissolved organic carbon (DOC) with stream discharge (Q), with points color-ramped by date. The inset panel (b) shows the change in the slope of increasing DOC with increasing Q from August - December in Beast Stream, VA.

2023-09-05 - Plont leads new paper on stream confluence biogeochemistry

Stephen Plont, a recent PhD graduate from our lab, recently published a chapter from his dissertation on biogeochemistry at stream confluences in Water Resources Research. The paper was co-authored by Durelle Scott and Erin Hotchkiss

We found that:

You can read more about our findings in the open access paper here and read highlights/key findings from Stephen here. Congratulations, Stephen!

Citation: Plont, S., Scott, D. T., & Hotchkiss, E. R. (2023). Biogeochemical processes are altered by non-conservative mixing at stream confluences. Water Resources Research, 59, e2022WR034224.

Figure 1 from Plont et al. 2023 showing the confluence sampling sites across the Toms Creek network as well as the sampling scheme within each confluence study site. 
Figure 5 from Plont et al. 2023: "Reach-scale mean water column microbial respiration rate (kDO) versus reach-scale coefficient of variation for wetted width (wcv; a and c) and water residence time normalized to a 100 m reach (WRT100m; b and d) along the upstream (a and b) and downstream (c and d) reaches of each confluence."

2023-08-23 - Hotchkiss co-authors paper on "carbon emissions along a stream network"

Erin Hotchkiss is co-author of an article, "Seasonality drives carbon emissions along a stream network" led by Hannah Conroy, a PhD candidate at the University of Washington collaborating on our NSF-funded Macrosystems project linking terrestrial and aquatic carbon fluxes and cycling. From the abstract: "Headwater stream networks contribute substantially to the global carbon dioxide terrestrial flux because of high turbulence and coupling with terrestrial environments. Heterogeneity within headwater stream networks, both spatially and temporally, makes measuring and upscaling these emissions challenging because measurements of carbon dioxide in streams are often limited to a few monitoring points. We modified a stream network model to reflect real measurements made under base flow and high flow conditions at Martha Creek in Stabler, WA in the US Pacific Northwest. We found that under high flow conditions, the stream network had much greater total carbon emissions than during low flow conditions (1.22 Mg C day−1 vs. 0.034 Mg C day−1). We attribute this increase to a larger overall stream network area (0.04 vs. 0.01 km2) and discharge (1.9 m3 s−1 vs. 0.005 m3 s−1) in November versus August. Our results demonstrate the need to understand the nonperennial stream reaches when calculating carbon emissions. We compared the stream network emissions with the terrestrial net ecosystem exchange (NEE) estimated by local eddy covariance measurements per watershed area (−5.5 Mg C day−1 in August and −2.2 Mg C day−1 in November). Daily stream emissions in November accounted for a much larger percentage of NEE than in August (54% vs. 0.62%). We concluded that the stream network can emit a large percentage of the forest NEE in the winter months, and annual estimates of stream network emissions must consider the flow regime throughout the year."

Citation: Conroy, H., E.R. Hotchkiss, K.M. Cawley, K. Goodman, R.O. Hall, J.B. Jones, W.M. Wollheim, & D. Butman. 2023. Seasonality Drives Carbon Emissions along a Stream Network. Journal of Geophysical Research – Biogeosciences 128: e2023JG007439.

Figure 6 (top) and Figure 7 (bottom) from Conroy et al. 2023, showing adjusted stream network model estimates of pCO2 and CO2 emissions across the Martha Creek network during low (August) and high (November) flow periods. 

2023-08-09 - Photos from the field: Delmarva wetlands

Carla López Lloreda and Emily Mulcahy recently conducted a research campaign to sample headwater wetlands on the Delmarva peninsula of Maryland, USA as part of our NSF-funded project assessing "Hydrologic Connectivity and Water Storage as Drivers of Carbon Export and Emissions from Wetland-Dominated Catchments". Carla's dissertation research includes assessing spatiotemporal patterns in carbon dioxide and methane in geographically-isolated wetlands, and testing how the concentration and emission of these greenhouse gases responds to changes in wetland water level, hydrologic connectivity among wetlands and their downstream fluvial network, and other environmental drivers. Emily is conducting undergraduate research linking high-frequency whole-ecosystem dissolved oxygen dynamics with chlorophyll-a, pelagic photosynthesis and respiration, hydrology, and carbon biogeochemistry in three wetlands that vary in morphometry, hydrologic connectivity, and fluvial network position. Pictures below from Carla!

2023-07-27 - Orlando presents summer research findings

Cleo Orlando, a Fralin Summer Undergraduate Research Fellowship (SURF) awardee conducting research with our lab group, presented a poster sharing results from "Exploring patterns in microbial activity across altered stream flowpaths" at Virginia Tech's Summer Undergraduate Research Conference. Cleo and mentor Katherine Pérez Rivera worked together to quantify spatiotemporal patterns in water quality and biogeochemical processes in the upper Stroubles Creek network that runs under and through Virginia Tech's campus, and includes the Duck Pond where Cleo focused her research on microbial carbon metabolism. Congratulations on a great poster presentation and thank you for a fun summer of research collaboration, Cleo!

Poster: Orlando, C., K.X. Pérez Rivera, & E.R. Hotchkiss. 2023. Exploring patterns in microbial activity across altered stream flowpaths. Virginia Tech Summer Undergraduate Research Conference, Blacksburg, VA, USA. 

Update (2023-09-18): Check out this VT news feature that highlights the experiences of the SURF researchers and mentors + a bonus photo of Cleo conducting stream sampling at the top of the article! 

Katherine Pérez Rivera and Cleo Orlando at Cleo's poster during the 2023 Virginia Tech Summer Undergraduate Research Conference.

2023-07-25 - Revisiting the Freshwater Imperative Workshop

After several COVID-19 delays, Erin Hotchkiss and fellow workshop steering committee members (Catherine O'Reilly, Kathy Cottingham, Steve Sadro, & Mike Vanni) finally hosted the NSF-funded "Revisiting the Freshwater Imperative" [hybrid] Workshop (originally planned for 2020)! It was an energizing and productive few days of discussing future research & science communication needs related to the sustainable management of global freshwater resources. Thank you to all of the  attendees for your enthusiasm and great ideas - we're excited for the ongoing and future collaborations emerging from this group!

Attendees (in person and remote) of the July 2023 "Revisiting the Freshwater Imperative" workshop hosted at Colorado State University. 

2023-06-21 - Photos from the field: Stroubles Creek & the Duck Pond

This summer Katherine Pérez Rivera is leading a project assessing all things carbon within the upper Stroubles Creek network, with a special focus on how the Duck Pond, a human-built pond on Virginia Tech's campus within the Stroubles Creek network, influences network carbon fluxes and metabolism. A sensor network has been installed in the inlets and outlet of the Duck Pond where we are collecting high-frequency conductivity, temperature, dissolved oxygen, water level, turbidity, and fluorescent dissolved organic matter data. Cleo Orlando, a Fralin Summer Undergraduate Research Fellow working with our lab, is assessing microbial metabolism of different carbon substrates above, within, and below the Duck Pond in collaboration with Katherine's dissertation research. Our goal is to understand how flow disruption within the stream network influences carbon transport into and out of the Duck Pond as well as how carbon and nutrient biogeochemistry changes during different flow conditions. 

Pictured below: Sampling, laboratory assays, and sensor installations above and below the Duck Pond, including rainy day sampling by Katherine, Cleo, Emily Mulcahy (an undergraduate researcher working with our lab)!

2023-06-20 - A few photos from Freshwater Sciences 2023 in Brisbane, Australia

Upper left -> right: Virginia Tech Stream Team members at the closing ceremony of the meeting (Carla, Sally, Sam, Katherine, Sergio [with his golden gumboot award!], Tyler [with his best poster presentation in applied research award!], Elizabeth, Meryl, & Erin); the Brisbane River & city wildlife; Summer 2023 graduate student and faculty members of the Hotchkiss Lab (Katherine, Erin, and Carla).

Lower left -> right: Carla giving her research presentation; Society for Freshwater Science leadership transition at the business lunch (Erin and Sherri are 2023-4 SFS VP and President, Steve and John were 2022-3 SFS President and VP); Katherine presenting her research poster.

2023-05-25 - Hotchkiss Lab & Friends @ Freshwater Sciences 2023

We're looking forward to reconnecting with and meeting new freshwater science colleagues in Brisbane! Talks and posters given or co-authored by members of our lab group are listed below. 

Please reach out if you would like to meet up with any of us. Erin will be at most if not all of the SFS-specific events, and is excited to talk with folks about how they can get more involved with the Society for Freshwater Science (SFS) in ways that ensure SFS continues to provide a uniquely supportive and intellectually stimulating environment for scientists of all backgrounds and career stages!

2023-05-25 - A few photos from graduation!

On 10 May 2023, Virginia Tech's Graduate School held the PhD hooding and graduation ceremony for all spring 2023 Master's and PhD graduates. Below are a few photos of Dr. Kristen Bretz and Dr. Stephen Plont (our lab) at graduation as well as Dr. Chloe Moore, who just completed her PhD with Dr. Meryl Mims. Congratulations, all!

Kristen & Erin at graduation

Erin & Stephen at graduation

Stephen, Erin, & Kristen after VT Graduate School's hooding and graduation ceremony

Chloe, Meryl, Stephen, Kristen, & Erin 

Chloe, Meryl, Erin, Stephen, & Kristen

2023-05-05 - Congratulations, Dr. Stephen Plont!

Stephen Plont passed his dissertation defense on 3 May 2023! After making a few dissertation revisions and working on peer reviewer-suggested revisions for his 3rd data chapter characterizing the role of stream confluences in river network biogeochemistry, Stephen will start a new position as a postdoctoral researcher with the AIMS project at the University of Alabama this summer! We're sad to say "goodbye for now" to Stephen, but are excited for the fun new collaborations and science in his future. Congratulations again, Dr. Plont!

Stephen Plont thanking the teams of colleagues, mentees, and friends who supported his data collection efforts during his public dissertation defense seminar on "Moving beyond the stream reach: Assessing how confluences alter ecosystem function and water quality in freshwater networks"

Dr. Plont signing the "graduates of the lab" cap during his post-defense celebration on the Derring Hall patio. Also pictured: labmates Carla López Lloreda and Kristen Bretz.

2023-05-02 - Pérez Rivera and López Lloreda co-author a note about their ASLO Global Outreach Initiative project

Katherine Pérez Rivera and Carla López Lloreda recently co-authored a note with Bianca Rodríguez-Cardona in the Association for the Sciences of Limnology and Oceanography (ASLO) Bulletin describing their ASLO-funded Global Outreach Initiative project, "Bringing Limnology and STEM Careers to Communities in Puerto Rico". 

You can read more about their project and find the latest resources developed by their team here:

¡Buen trabajo, Carla, Katherine y Bianca!

Figure 3 from the Rodríguez-Cardona et al. L&O Bulletin article. "Word clouds from before and after the panel discussion where participants were asked: (A) ¿Qué es para ti un/a científico/a? (How do you describe a scientist?) and (B) ¿Qué aprendiste de ser un/a científico/a? (What did you learn about being a scientist?)."

2023-04-24 - Congratulations, Dr. Kristen Bretz!

Kristen Bretz passed her dissertation defense on 19 April 2023! After making a few dissertation revisions and working on peer reviewer-suggested revisions for her 2nd data chapter during the final weeks of the spring semester, Kristen will start a new position as the Assistant Director of Virginia Tech's Office of Undergraduate Research (VT OUR) this summer! We're thrilled we don't have to say a big "goodbye" to Kristen since she's staying in Blacksburg and excited to see all of the great work Kristen will accomplish with VT OUR. Congratulations again, Dr. Bretz!

Kristen Bretz concluding her public dissertation defense seminar on "Headwater stream network connectivity: Biogeochemical consequences and carbon fate"

Lab members celebrating on the Derring Hall patio after Kristen's PhD committee approved of her passing her defense (left to right): Carla López Lloreda , Erin Hotchkiss, Kristen Bretz, Katherine Pérez Rivera, & Stephen Plont

2023-04-17 - Plont PhD Defense Seminar on 3 May!

Stephen Plont will share the results of his PhD research during a public seminar on 3 May 2023 at 9:30am in the Steger Auditorium. Stephen's dissertation is titled "Moving beyond the stream reach: Assessing how confluences alter ecosystem function and water quality in freshwater networks", and includes two chapters already published on (1) "Linking Carbon and Nitrogen Spiraling in Streams" and (2) "Integrating perspectives on dissolved organic carbon removal and whole-stream metabolism".

General audience abstract from Stephen's dissertation submitted to his PhD committee:

"Streams receive and use materials from upstream and the surrounding landscape to fuel in-stream ecosystem processes (e.g. carbon and nutrient cycling). Understanding how these processes within a stream alter concentrations of carbon and other nutrients is needed to assess how the ecosystem is functioning and what the consequences are on water quality downstream. Further, predictions of how materials cycle and move at the scale of streams networks are derived from measurements at the stream reach scale. As a result, the impact of stream confluences (i.e., where two streams meet and mix) on in-stream carbon and nutrient cycling and the consequences on downstream water quality has been overlooked. In this dissertation, I seek to address the following questions: (1) How are carbon and nitrogen cycles linked in streams and how those links altered by land use? (2) How can rates of in-stream carbon cycling inform our understanding of the role of streams in landscape carbon budgets? (3) How are carbon and nutrient removal altered downstream of a stream confluence? (4) How do confluences alter water chemistry within a freshwater network? 

In Chapter 2, I showed that organic carbon and nitrate shared similar fates in streams across the United States. Organic carbon traveled longer distances before being respired in agricultural and urban streams compared to natively-vegetated streams, suggesting that human modifications to landscapes impact carbon cycling and transport in streams. In Chapter 3, I demonstrated how rates of in-stream organic carbon removal can be used to understand land-stream connections. In Chapter 4, I conducted whole-ecosystem experiments to assess how carbon and nutrient removal are altered by a confluence. I showed that carbon metabolism and phosphorus removal are suppressed downstream of a confluence and that rates of organic carbon removal are spatially variable throughout where water from the two streams are mixing. In Chapter 5, I examined potential drivers to explain patterns of organic matter and nutrient chemistry downstream of confluences throughout a stream network. Reaches downstream of confluences were physically, chemically, and biologically distinct from upstream reaches and differences in upstream and tributary reach chemistry or drainage area did not explain patterns of water chemistry downstream of confluences. 

Overall, my dissertation highlights the importance of processes within a stream in driving carbon and nutrient cycling, and how rates of whole-stream carbon cycling can be used to better understand connections between streams and the surrounding landscape. I investigate the role of stream confluences in determining the cycling and downstream fate of carbon and nutrients in freshwater networks. This work shows that ecosystem functioning and downstream water quality in freshwater networks are affected by processes occurring within streams and by the interfaces between streams and other ecosystems (e.g., land-water interfaces, stream confluences)."

2023-04-06 - Bretz PhD Defense Seminar on 19 April!

Kristen Bretz will share the results of her PhD research during a public seminar on 19 April 2023 at 1:00 pm in Derring Hall 2084. Kristen's dissertation is titled "Headwater stream network connectivity: Biogeochemical consequences and carbon fate", and includes one chapter already published in the Journal of Geophysical Research – Biogeosciences on "Integrating ecosystem patch contributions to stream corridor carbon dioxide and methane fluxes".

General audience abstract from Kristen's dissertation submitted to her PhD committee:

"Headwater streams may seem inconsequential to larger ecosystem processes due to their small size. However, the majority of a river’s network length, or the total length of all the streams and rivers, from spring to ocean, is made up of headwater streams. The widespread presence of headwater streams over all types of land, along with the unique layout of different aquatic habitats near streams and the fact that small streams often grow and shrink in length, mean that studying headwaters can tell us many things about how energy moves through ecosystems. 

This dissertation explores how we can use changing headwater connectivity to understand how carbon moves through ecosystems. Connectivity in aquatic science refers to how water can move through space in ways that rocks and trees and even many animals cannot. This idea is useful because water carries things around as it moves, and its presence or absence enables reactions that are essential for the cycling of energy and nutrients. For instance, when water moves from high ground to low ground, it navigates through soil and holes in the ground; it may get slowed down at flat spots where little pools form. I measured emissions of carbon dioxide and methane from streams as well as soils, holes, and pools near mountain streams to try to understand how the path water takes influences how much carbon dioxide and methane escapes into the air. My measurements were surprisingly different depending on where and when I took them. I found that if a seasonal pond is connected to a stream channel, the stream will emit more greenhouse gasses than if the pond goes dry. 

Connectivity can also describe if water moves continuously along a stream, or if the stream goes dry in places and is then disconnected from different parts of itself. I asked how a stream becoming disconnected affected carbon dioxide emissions as well as the movement of dissolved organic carbon, a food source for microorganisms. I found that the less water moving through the stream channel, the higher carbon dioxide concentrations were. I also found that storms move both carbon dioxide and dissolved organic carbon out of streams quickly, even if the stream had been disconnected. Finally, I investigated the water that is left when streams disconnect. I measured dissolved oxygen, carbon dioxide, and methane in isolated pools of two disconnected streams. By tracking how microbes and algae consume and produce oxygen when a stream is not flowing, I can understand how these lifeforms adapt. I found that isolated pools frequently have very low levels of dissolved oxygen. This means that microorganisms in the pools have to use special ways of getting energy, which in turn affects how different forms of carbon move through the stream ecosystems. 

Headwater stream ecosystems are very sensitive to small changes in flow and precipitation; however, climate change means that streams are going dry more often than they used to. My findings contribute to our understanding of how changes in stream connectivity have many biological effects that are important for water quality and ecosystem health."

2023-04-03 - Hotchkiss co-authors paper on stream greenhouse gas concentrations 

Erin Hotchkiss is co-author of an article on "Variability and drivers of CO2, CH4, and N2O concentrations in streams across the United States" led by Amanda DelVecchia. From the abstract: "We present a first analysis of such a dataset collected by the National Ecological Observatory Network across 27 streams and rivers across ecoclimatic domains of the United States [and Puerto Rico]. ... CO2 and CH4 were strongly affected by physical drivers including mean air temperature and stream slope, as well as by dissolved oxygen and total nitrogen concentrations. N2O was exclusively correlated with total nitrogen concentrations. Results suggested that potential for gas exchange dominated patterns in gas concentrations at the site level, but contributions of in-stream aerobic and anaerobic metabolism, and groundwater also likely varied across sites. The highest gas concentrations as well as highest variability occurred in low-gradient, warmer, and nonperennial systems. These results are a first step in providing unprecedented, continuous estimates of GHG [greenhouse gas] flux constrained by temporally variable physical and biogeochemical drivers of GHG production."

Citation: DelVecchia, A.G., Rhea, S., Aho, K.S., Stanley, E.H., Hotchkiss, E.R., Carter, A. and Bernhardt, E.S. (2023), Variability and drivers of CO2, CO2, and N2O concentrations in streams across the United States. Limnology & Oceanography 68: 394-408. 

Figure 8 from DelVecchia et al. 2023: "Pearson correlation coefficients for each combination of site-scale variables: Temperature (°C), watershed and stream slopes (°), mean annual precipitation (mm yr−1), DOC and TN concentrations (mg L−1), and gas concentrations (μmol L−1), are shown by a color gradient from gray (−1) to red (+1). Significance levels include 0.1 (*), 0.05 (**), and 0.01 (***). CO2, CH4, DOC, and TN were all log10-transformed."

2023-02-14 - Hotchkiss is an ASLO Fellow

Erin Hotchkiss was recognized as a 2022 Fellow of the Association for the Sciences of Limnology and Oceanography (ASLO) for "achieved excellence in ... contributions to ASLO and the aquatic sciences". 

Congratulations to all new ASLO Fellows and Sustaining Fellows! 

ASLO Announcement: 

Photographs and names of the 2022 ASLO Fellows. Source:   

2023-02-13 - Pérez Rivera co-authors article on "Soil solution data from Bohemian headwater catchments"

Katherine X. Pérez Rivera is co-author of an article on "Soil solution data from Bohemian headwater catchments record atmospheric metal deposition and legacy pollution" led by Daniel Petrash and co-authored with other scientists from the Czech Geological Survey. This collaboration emerged during Katherine's time as a Fulbright Research Fellow in the Czech Republic during 2021-2022.

From the abstract: "Our aim was to test the feasibility of lysimeters’ hydrochemical data as a gauge for legacy subsoil pollution. Due to contrasting lithologies, atmospheric legacy pollution prevailing at the soil-regolith interface is differently yet consistently reflected by beryllium, lead, and chromium soil solution concentrations of the three catchments. Geochemical (dis)equilibrium between the soil and soil matrix water governed the hydrochemistry of the soil solutions at the time of collection, potentially contributing to decreased dissolved concentrations with increased depths at sites with higher soil pH. A complementary isotopic δ18O runoff generation model constrained potential seasonal responses and pointed to sufficiently long water-regolith interactions as to permit important seasonal contributions of groundwater enriched in chemical species to the topsoil levels. Our study also reflects subsoil equilibration with atmospheric solutes deposited at the topsoil and thus provides guidance for evaluating legacy pollution in soil profiles derived from contrasting lithology."

Citation: Petrash, D.A., Krám, P., Pérez-Rivera, K.X., Bůzek. F., Čuřík, J., Veselovský, F. & Novák, M. 2023. Soil solution data from Bohemian headwater catchments record atmospheric metal deposition and legacy pollution. Environ Sci Pollut Res. 

2023-02-06 - Bretz, Plont, and Pérez Rivera share their science at VT Biological Sciences Research Day

Several folks in our lab group shared recent results from their dissertation research at this year's Biological Sciences Research Day, an annual event to celebrate graduate student research accomplishments in the Department of Biological Sciences at Virginia Tech. Great work, everyone!

Pictured (left -> right): Erin Hotchkiss, Kristen Bretz, Katherine Pérez Rivera, Stephen Plont, & Carla López Lloreda at 2023 Biological Sciences Research Day

2023-02-01 - Hotchkiss co-authors Nature review article

Erin Hotchkiss is co-author of an article on "River ecosystem metabolism and carbon biogeochemistry in a changing world" led by Tom Battin and co-authored with experts in carbon biogeochemistry, hydrology, and ecosystem metabolism of streams, rivers, and fluvial networks. From the abstract: "...we review the state of river ecosystem metabolism research and synthesize the current best available estimates of river ecosystem metabolism. We quantify the organic and inorganic carbon flux from land to global rivers and show that their net ecosystem production and carbon dioxide emissions shift the organic to inorganic carbon balance en route from land to the coastal ocean. Furthermore, we discuss how global change may affect river ecosystem metabolism and related carbon fluxes and identify research directions that can help to develop better predictions of the effects of global change on riverine ecosystem processes. We argue that a global river observing system will play a key role in understanding river networks and their future evolution in the context of the global carbon budget."

Citation: Battin, T.J., E. Bernhardt, E. Bertuzzo, L. Gómez Gener, R.O. Hall, E.R. Hotchkiss, R. Lauerwald, T. Maavara, T. Paveksly, L. Ran, P. Raymond, P. Regnier, & J. Rosentreter. 2023. River ecosystem metabolism and carbon biogeochemistry in a changing world. Nature 613: 449-459.  

Press Release by École Polytechnique Fédérale de Lausanne: Why Rivers Matter for the Global Carbon Cycle

2023-01-19 -  Plont co-authors article on "Priorities for Synthesis Research in Ecology and Environmental Science"

Stephen Plont is co-author of a new article in Ecosphere characterizing "Priorities for Synthesis Research in Ecology and Environment Science". This paper was the result of a 2021 virtual workshop through the National Center for Ecological Analysis & Synthesis that brought together over 120 scientists from across the globe to brainstorm and produce a guide for collaborative projects looking to address pressing questions around global change over the next decade.


From Stephen: "It has been such a rewarding experience to be part of this collaborative project through NCEAS. One of the major themes to emerge from this paper is a call to increase participant diversity and inclusive research practices in synthesis-driven environmental science questions and I felt that this workshop and manuscript set a standard for large-scale, interdisciplinary, and inclusive collaboration going forward. As a graduate student in a group that spanned the full range of career stages and disciplinary boundaries, I am grateful to see the perspective of so many early career stage researchers helping dictate the direction of global change science in the coming decades. I know I will be coming back to his paper and the lessons I learned from this collaboration throughout my research career."


Citation: Halpern, B. S., C. Boettiger, M. C. Dietze, J. A. Gephart, P. Gonzalez, N. B. Grimm, P. M. Groffman, … S. Plont…et al. 2023. “Priorities for Synthesis Research in Ecology and Environmental Science.” Ecosphere 14(1):e4342.


Link to paper:


Link to press release:

Figure 1 from Halpern et al.: "Our approach to engaging participants and all perspectives in developing, honing, and presenting the set of questions and ideas that form the basis for our recommended priorities. DEIJ is diversity, equity, inclusion, and justice."