COLLOID MOBILIZATION AND BIOGEOCHEMICAL CYCLING OF ORGANIC CARBON, NITROGEN AND PHOSPHOROUS IN WETLANDS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1000889
• Grant No.: 2013-67019-21361
• Cumulative Award Amt.: $408,500.00
• Proposal No.: 2013-02772
• Project Start Date: Sep 1, 2013
• Project End Date: Aug 31, 2018
• Grant Year: 2013
• Program Code: [A1401]- Foundational Program: Soil Health

Recipient Organization
UNIVERSITY OF DELAWARE
(N/A)
NEWARK,DE 19717

Performing Department
Plant & Soil Science

Non Technical Summary
Wetlands, because of their ability to remove nutrients and pollutants before they enter downstream waters, are a valuable component of integrated approaches to manage impairing water resources at the urban-agricultural interface. The biogeochemical processes that control the retention, transformation, and transport of nitrogen (N), phosphorous (P), dissolved organic matter (DOM) and how these processes are affected by colloid mobilization need to be systematically evaluated. Our hypothesis is that iron reduction-oxidation events in redox-dynamic wetlands can cause wide shifts in concentrations of colloids and dissolved materials. The goal of the proposed project is to provide a comprehensive investigation on the mechanisms and processes that control the fate and transport of nutrients (N and P) and DOM in wetland environments characterized by hydrologic and redox flux. The objectives will be accomplished through extensive ground water and surface water sampling at three selected freshwater wetland sites (where we have long-term monitoring data) which represent a range in hydroperiod and hydrodynamics, and complimentary laboratory experiments. Water samples will be taken at wetland inlets and outlets and analyzed for concentration and forms of N, P, Fe, OM, and mobile colloids. Batch and column experiments will be run to elucidate the mechanisms of colloid mobilization and the role of mobile colloids in the fate and transport of N, P, and OM. Laboratory and field studies will be integrated: field observations will be used to determine the critical parameters to be examined in laboratory experiments and laboratory results will provide mechanistic interpretation of field data.

Animal Health Component

35%

Research Effort Categories

Basic

65%

Applied

35%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
133	0330	1000	100%

Knowledge Area
133 - Pollution Prevention and Mitigation;

Subject Of Investigation
0330 - Wetland and riparian systems;

Field Of Science
1000 - Biochemistry and biophysics;

Keywords

soil

water

Goals / Objectives
The goal of the proposed project is to provide a comprehensive investigation on the mechanisms and processes that control the fate and transport of N, P, and DOM in the unique wetland environment subject to a large range of hydrological and redox conditions; with a special emphasis in the role of colloid mobilization in these processes. Objectives of Proposed Project: (1) To quantify the amount of inorganic N, dissolved and colloidal forms of P, DOM and colloidal OM at the hydrologic inlet and outlet of wetlands; (2) to quantify the amount of colloids mobilized and evaluate their role in the cycling of N, P and DOM in wetlands; (3) to elucidate the mechanisms and dynamic interplay between colloid mobilization and stability, redox conditions, and DOM concentration; and (4) to assess the impact of wetland hydroperiod fluctuations and hydrodynamics on these processes.

Project Methods
The objectives will be accomplished through extensive field sampling at selected wetland sites (where we have long-term monitoring data) and complimentary laboratory experiments. The selected field sites represent a range in hydroperiod and hydrodynamics, and therefore a range in redox conditions. We will measure the concentrations and identify the forms of N, P, Fe, OM, and mobile colloids in the inlet and outlet of wetlands. We will conduct batch and column experiments to elucidate the mechanisms of colloid mobilization and the role of mobile colloids in the fate and transport of N, P, and OM. The laboratory and field studies will be closely integrated: field observations will be used to determine the critical parameters to be closely examined in laboratory experiments and laboratory results will provide mechanistic interpretation of field data. Interpretation of the data generated by laboratory analyses of water samples (N, P, colloids, DOM) require characterization of soil conditions (e.g., saturation, Eh) and hydrologic conditions (rising, falling, or static water table) at time of sample collection. These characterizations will be based on data collected from direct measurement of soil Eh (Pt electrodes), identification of reducing conditions (IRIS tubes), and monitoring well and piezometer measurements. To allow for extrapolation of results (application to similar wetlands) we will determine if the samples were collected during a year with a "representative" hydroperiod. This determination will be based on time sequence analysis (JMP software, S.A.S. Institute, Cary N.C.) comparing water table data from the year in question to our long-term monitoring data for each site. The data from these experiments will be used to assess the release and transport characteristics of DOM and colloids under the various experimental conditions to be examined in the proposed project. The existing HYDRUS 1-D code that has incorporated a colloid transport segment and a wetland module (Šim?nek,http://www.pc-progress.com/en/Default.aspx?jirka-simunek) will be used to quantify the experimental results. In the event that the existing models cannot be used to describe the complex interplay between DOM, colloids and redox conditions, we hope to provide experimental basis for the conceptualization of the reactions/processes so that a model suitable for describing such processes may be developed in the future. Project Schedule Year 1 Install wells in field sites in September and October Sampling field soils and collect soil samples for laboratory experiments in September and October Taking water samples from field sites in October, January, April, July Analyzing field water samples Conducting batch experiments Present and write manuscripts based on research results, prepare and submit annual report Year 2 Taking water samples from field sites in October, January, April, July Analyzing field water samples Complete batch experiments Conduct column experiments Present and write manuscripts based on research results, prepare and submit annual report Year 3 Taking water samples from field sites in October, January, April, July Analyzing field water samples Conduct column experiments Present and write manuscripts based on research results, prepare and submit annual report Year 4 Taking water samples from field sites in October, January, April, July Complete field water sample analysis Finish column experiments Present and write manuscripts based on research results, prepare and submit final report

Progress 09/01/13 to 08/31/18

Outputs
Target Audience:Presentations were given at conferences for the Soil Science Society of America, Society of Wetland Scientists, and American Geophysical Union. The audiences at these presentations were predominately scientists and graduate students of multiple disciplines (soil science, biogeochemistry, environmental fate and transport, and wetland science). Presentations were also given at workshops for the Mid-Atlantic Hydric Soils Committee. Audiences for these workshops include college professors, graduate students, Federal environmental personnel (EPA, USACE, USDA, USF&W), state environmental personnel, and private consultants. Changes/Problems:We initially did not expect ferrous iron in the groundwater samples to be oxidized very quickly to ferric iron upon sample collection. We initially used acid to prevent this but this proved to be inadequate. We switched to filling the collection bottles with argon prior to sample collection. This proved to be superior. Otherwise, we did not have any major issues in sample collection, sample analysis, and data analysis. What opportunities for training and professional development has the project provided?Mr. Matt King was an undergraduate helper on the project. He learned and then used all of the field techniques required for the project. He recently received an M.S. in Soil Science and is now a private consultant in Delaware. Mr. Ronald Manelski is an M.S. candidate in Soil Science. He learned and then used all of the lab and field techniques required for the project. He was writing his thesis when he became ill. He is on medical leave. Dr. Jing Yan was a Ph.D. candidate working on the project. He learned and then used all of the field techniques required for the project. Dr. Yan is now a post-doc. How have the results been disseminated to communities of interest?Presentations were given at conferences for the Soil Science Society of America, Society of Wetland Scientists, and American Geophysical Union. The audiences at these presentations were predominately scientists and graduate students of multiple disciplines (soil science, biogeochemistry, environmental fate and transport, and wetland science). Presentations were also given at workshops for the Mid-Atlantic Hydric Soils Committee. Audiences for these workshops include college professors, graduate students, Federal environmental personnel (EPA, USACE, USDA, USF&W), state environmental personnel, and private consultants. A paper has been accepted in a scientific journal, Frontiers in Science. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Objective 1: This objective was completely met. We have an extensive data set on ammonium, nitrate, dissolved organic carbon (DOC), ortho-phospate, ferrous iron (Fe2 ), and colloidal organic matter. Objective 2: We have extensive data on colloid mobilization. Objectives 2 & 3: For all sites and sampling plots, colloids were correlated with ammonium, nitrate, and DOC. We did not see any correlation with ortho-phosphate. Objective 4: The three wetlands sampled had very different hydroperiods and hydrodynamics. Not surprisingly the data varied considerably with site. Overall, water table depth was correlated with colloid levels, DOC, total dissolved solids, and ferrous iron. For a specific site, the water table was correlated with the most water chemistry variables at Blackbird, the wetland with the most dynamic water table. There were no correlations with water table at Devils Hole, trhe wetland with a very stable water table. Overall, this project was a success as we have data establishng the impact of hydroperiod on watr chemistry. These results should be considered when developing a water sampling scheme for wetlands, and when interpreting water chemistry data.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Jin, Y., Yan, J., Vasilas, B. & Manelski, R. Dynamic Release and Transport of Colloids and Colloidal Organic Carbon in a Seasonally Saturated Wetland. American Geophysical Union Conference. San Francisco: AGU.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Vasilas, B. L., Manelski, R., Jin, Y., & Yan, J. Colloid Mobilization and Biogeochemical Cycling of Organic Carbon, Nitrogen and Phosphorous in Wetlands. AFRI NIFA Workshop. Washington DC: USDA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Manelski, R., Vasilas, B., Jin, Y., & Yan, J. Bridging the scale: Connecting the colloid scale to wetland diversity. Society of Wetland Scientists Conference. Corpus Christi TX2017
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Manelski, R., Vasilas, B., Jin, Y., & Yan, J. Bridging the scale: Connecting the colloid scale to wetland diversity. Soil Science Society of America Conference. Phoenix AZ
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Manelski, R., Vasilas, B., & Yan, J. Bridging the scale: Connecting the colloid scale to wetland diversity. MAHSC Workshop. Raleigh, NC
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Jing, Y., R. Manelski, B. Vasilas, and Y. Jin. Mobile Colloidal Organic Carbon: An Underestimated Carbon Pool in Global Carbon Cycles? has been approved for production and accepted for publication in Frontiers in Environmental Science, section Soil Processes.