Current Projects 


Photodegradation of Insecticides in Rivers Adjacent to Agricultural Intensive Regions: A Novel Water Quality Monitoring Approach, USDA-NIFA, T. Messer, D. Snow, and M. Doyle, 3/1/18-2/28/2022

Worldwide chronic levels of insecticides in rivers continue to rise, which have significant human health and food security implications. Insecticides, once in the environment, are exposed to a range of environmental conditions, resulting in degradation and formation of potentially harmful byproducts. The overarching goal of the proposed work is to quantify the potential role of river geomorphology on photochemical transformation fate and degradation rates of two insecticides that are contaminants of emerging concern (CECs): Imidacloprid and Clothiandin. Path-specific environmental conditions of two agricultural impacted rivers in the Midwest and Southeast will be assessed. Objectives include three coupled field/laboratory research schemes: 1. Sypnotic, 2. Eulerian, and 3. Lagrangian. Each objective will incorporate the development of alternative field and sensor-based approaches for studying rivers in agroecosystems. The novelty of the proposed work is we will conceptually and methodologically follow variable conditions experienced by a water particle as it travels through a river using passive drifting sensors, ultimately providing a more accurate picture of CEC fate and transport. Expected deliverables include: 1. Provide realistic recommendations for minimizing environmental impacts of these insecticides, 2. Improve current fate and transport methodology that will be transferable and scalable to other questions in rivers adjacent to agrosystems (e.g., nutrient retention), and 3. Provide undergraduate and graduate training.

Influence of Agrochemical Mixtures on Treatment Wetland Ecosystem Services, USDA-NIFA, S. Bartelt-Hunt, T. Messer, and D. Snow, 05/01/2019-04/30/2023

This project will evaluate the discrete and combined effects of specific veterinary antibiotics and an increasingly used nitrification inhibitor (nitrapyrin) to nitrogen transformation and its potential effect on nitrate-N treatment efficiency in saturated sediments and wetlands. Specific research objectives of our project are to:  1) simulate and quantify the combined effects of antibiotics and a commercial nitrification inhibitor on the nitrogen cycle in saturated pulse flow treatment wetlands; and 2) determine the overall effect of trace levels of antibiotics and nitrification inhibitors on the nitrate-N removal potential of pulse flow wetlands receiving contaminated agricultural run-off.  We will first conduct microcosm incubations at a USGS research laboratory to establish the concentration levels where nitrapyrin and antibiotic mixtures affect nitrate transformation. Nitrogen and antibiotic transformation, and nitrapyrin interactions will be assessed in two sets of mesocosm wetland experiments using methods from past successful simulations. The transformation and fate of selected veterinary antibiotics will also be tracked in the mesocosms. Findings will provide new insight into whether residues of nitrification inhibitors and veterinary antibiotics in these environments will affect proposed mitigation strategies for controlling nitrogen losses from fertilized crops and managing nitrate contamination of ground and surface water. This project will accelerate research programs of two early career scientists, foster collaborations with an established USGS biogeochemist and USDA-ARS microbiologist, and will train a PhD student in environmental analytical and stable isotope methods. All activities will help to further our understanding of the potential effects of specific contaminant mixtures on nitrogen biotransformation in wetlands designed to treat run-off from urban and agricultural watersheds. Findings from this study will be disseminated through research presentations, high impact journal articles, local seminars, national conferences, technical workshops, a public magazine article, public outreach presentations, and an undergraduate wetlands class. 

Investigating mobile genetic elements and resistance gene reservoirs towards understanding the emergence and ecology of antimicrobial resistance in beef cattle production systems, USDA-NIFA, S. Fernando, S. Bartlett-Hunt, D. Loy, T. Messer, G. Morota, H. Paz Manzano, A. Schmidt, D. Snow, and R. Stowell. 2/15/2018 – 2/14/22

Our preliminary studies and proposed experiments employ some of the most powerful, genome-based methodologies and analytical chemistry methods to identify antimicrobial compounds, and genes in the environment. These approaches will be applied to both antibiotic free and antibiotic treated cattle and pens and will be implemented at the U.S. Meat Animal Research Center new antibiotic free feedlot facility. We will further our strong relationships with Nebraska and the central Plains beef producers and will work closely with them to implement our research findings. At the completion of the project, the expected outcomes of outreach activities are: 1. Improved access among producers, consumers, stakeholders and their advisors to research-based information, tools and resources communicated in a way that facilitates improved understanding of potential AMR-related food safety risks; and 2. Improved ability among producers, consumers, stakeholders and their advisors to assess and adopt practices to mitigate potential AMR-related food safety risks. 

LTAR Research: Testing a Novel Groundwater Age-dating Technique in Bazile Creek Watershed, T. Messer, T. Gilmore, and A. Mittelstet, 11/1/2019 – 10/30/2021

This project will assess groundwater transient times in a Nebraska watershed to determine new methods to determining goundwater age. The project is a subproject of a larger grant awarded to Dr. Tala Awada. Results from the project will aide in identifying age of nitrate contamination is within groundwater systems in a region of Nebraska with nitrate concentrations exceeding Environmental Protection Agency health requirements for drinking water from wells.

Nebraska Floating Wetlands Pilot Project,  T. Messer, 12/10/2019-12/09/2020

The purpose of this project is to reduce phosphate and nitrate concentrations and improve water clarity of a eutrophic pond using a sustainable system. The goals of this project are to 1) Improve the water quality of Cooper Pond by quantifying floating treatment wetland survival and growth under field conditions present in Cooper Pond and  floating treatment wetland efficacy of reducing nitrate and phosphate concentrations and 2) Provide Outreach and Training on Benefits of Floating Treatment Wetland by installing a time-lapse camera to visually show the benefit of the Floating Treatment Wetlands and conducting at least two (2) public trainings to outline the benefits of the project.

PFAS Exposure from WWTPs to Surface Water and Agricultural Fields. USGS 104(b). T. Messer, S. Bartelt-Hunt, and D. Snow,  3/1/2020 – 2/28/2021.

The project will investigate PFAS exposure upstream and downstream of a wastewater treatment plant. Further, biosolids will be applied to agricultural fields and fate and transport of PFAS in runoff, soil, and plant uptake will be evaluated. 

FIRST: Treating Non-Point Source Cocktails: Pesticide Removal Utilizing In-stream Best Management Practices, NSF-Nebraska-EPSCoR, T. Messer.  4/1/2019-9/31/2020

Activities to be supported by the first award include: FTW laboratory mesocosm experimental evaluations of one of the proposed mesocosm pesticide experiments. This activity will provide important seed data for a full NSF CAREER proposal, and will provide graduate student and UCARE undergraduate training. At least one peer-reviewed journal publication is expected from this research. Other activities planned during the First Award include: 1. Securing letters of support from Nebraska One Health, Nebraska Department of Environmental Quality, Nebraska Natural Resource Districts, Arbor Day Foundation Nature Explore Pre-K Program, Lincoln Public Schools, and American Cancer Foundation, all of which have expressed interest in the project, and 2. Developing an activity in the mesoLab focused on pesticide removal in wetlands for use in Lincoln Public Schools, UNL sponsored high school camps, and an undergraduate wetlands course taught be PI Messer.

Treating Non-Point Source Cocktails: Pesticide Removal Utilizing In-stream Best Management Practices, Robert B. Daugherty Water for Food Global Institute at the University of Nebraska, T. Messer 7/1/2019-6/30/2020

The project investigates the potential of floating treatment wetland to improve water quality in local recreational lake waters that have high pesticide inputs. Seasonal and vegetation design impacts on floating treatment wetland treatment potential will be evaluated. The project will provide support for the Nebraska Department of Environmental Quality and to incorporate FTWs as an approved best management practice for watershed management plans and better understand nutrient removal when exposed to pesticides. Further, the project will provide a first look at realistic assessments of the environmental conditions and their impacts on treatment and prevention potential of FTWs for pesticide removal in the Midwest. These findings may be applicable to treating water in smaller waterbodies (e.g., agricultural ponds) critical to agriculture in the Midwest. Lastly, the project will provide graduate and undergraduate training, hands-on experiences for a wide range of students through the mesoWheels program along with practitioner training and citizen science activities.


Peer-Reviewed Publications


1. Hansen, S.2Messer, T.L., Mittelstet, A., Berry, E.D., Bartelt-Hunt, S., Abmibola, F.  2020. Escherichia ColiConcentrations in Waters of a Reservoir System Impacted by Cattle and Migratory Waterfowl. STOTEN. 705(25), (Impact Factor: 5.589/ Cite Score: 5.92

2. Messer, T.L., K.R. Douglas-Mankin, N.G. Nelson, and J.R. Etheridge. 2019. Wetland Ecosystem Resiliency: Protecting and Restoring Value Ecosystems. Transactions of American Society of Agricultural and Biological Engineering,62(2): 1541-1543. doi: 10.13031/trans.13578. (Impact Factor: 3.82)

3. Keilhauer, M.2Messer, T. L., Mittelstet, A., Corman, J., Franti, T. 2019. Nitrate Removal Potential of Floating Treatment Wetlands Amended with Spent Coffee: A Mesocosm Scale Evaluation. Transactions of American Society of Agricultural and Biological Engineering. 62(6): 1619-1630. doi: 10.13031/trans.13431. (Impact Factor: 3.82)

4. Hansen, S.2T. L. Messer, and A. Mittelstet. 2019. Mitigating the Risk of Atrazine Exposure Across Nebraska, USA: Identifying Hot Spots and Hot Times in Surface Water Watersheds. Journal of Environmental Management, 250: 109424. doi: 10.1016/j.jenvman.2019.109424. (Impact Factor: 4.865/ Cite Score: 5.32)

5. Messer, T.L., F. Bírgand, and M.R. Buchell. 2019. Diel Fluctuations of High Level Nitrate and Dissolved Organic Carbon Concentrations in Constructed Wetland Mesocosms. Ecolological Engineering, 133: 76-87. doi:10.1016/j.ecoleng.2019.04.027. (Impact Factor: 3.406/ Cite Score: 3.73)

6. Mittelstet, A. R., Gilmore, T. E., Messer, T.L., Rudnick, D. R., Heatherly, T. 2019. Evaluation of Watershed Characteristics to Identify Best Management Practices to Reduce Nebraskan Nitrate Concentrations from Nebraska to the Mississippi/Atchafalaya River Basin. Agriculture, Ecosystems, and the Environment. 277: 1-10. doi. 10.1016/j.agee.2019.02.018. (Impact Factor: 3.954/ Cite Score: 4.42)

7. Messer, T.L., M.R. Burchell, and F. Bírgand. 2017. Comparison of Four Nitrate Removal Kinetic Models in Two Distinct Wetland Restoration Mesocosm Systems. Water, 9: 517-537. doi. 10.3390/w9070517(Impact Factor: 2.524/ Cite Score: 2.66)

8. Messer, T.L., M.R. Burchell, F. Bírgand, S. Broome, and G. Chescheir. 2017. Nitrate Removal Potential of Restored Wetlands Loaded with Agricultural Drainage: A Mesocosm Scale Experimental Approach, Ecological Engineering, 106: 541-554. doi. 10.1016/j.ecoleng.2017.06.022. (Impact Factor: 3.406/ Cite Score: 3.73)

9. Messer, T.L., M.R. Burchell, J.K. Böhlke, and C.R. Tobias. 2017. Tracking the Fate of Nitrate through Restored Wetlands: A Mesocosm Scale 15N Enrichment Tracer Study, Ecological Engineering, 106: 597-608. doi. 10.1016/j.ecoleng.2017.06.016(Impact Factor: 3.406/ Cite Score: 3.73)

10. Wiseman, J., M.R. Burchell, G.L. Grabow, D.L. Osmond, and T.L. Messer. 2014. Groundwater nitrate concentration reductions in a riparian buffer enrolled in the NC Conservation Reserve Enhancement Program. Journal of American Water Resources Association, 50(3): 653-664. doi. 10.1111/jawr.12209. (Impact Factor: 2.462/ Cite Score: 2.49)

11. Messer, T. L., M.R. Burchell, D.L. Osmond, and G.L. Grabow. 2012. Groundwater Nitrate Reductions within Upstream and Downstream Sections of a Riparian Buffer. Ecological Engineering, 47: 397-407. doi. 10.1016/j.ecoleng.2012.06.017. (Impact Factor: 3.406/ Cite Score: 3.73)

In Press

1. Abimbola, O.P., Mittelstet, A.R., Messer, T.L., Berry, E.D., Bartelt-Hunt, S.L., and Hansen, S.P.2 2020. PredictingEscherichia coli loads in cascading dams with machine learning: An integration of hydrometeorology, animal density and grazing pattern. STOTEN. (Impact Factor: 5.589/ Cite Score: 5.9)