Grantee Research Project Results
Dissolved Organic Nitrogen Transport and Transformations From Tile-Drained Agricultural Systems to Surface WatersEPA Grant Number: FP917298
Title: Dissolved Organic Nitrogen Transport and Transformations From Tile-Drained Agricultural Systems to Surface Waters
Investigators: Jelinski, Nicolas A
Institution: University of Minnesota
EPA Project Officer: Cobbs-Green, Gladys M.
Project Period: September 1, 2011 through August 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011)
Research Category: Academic Fellowships , Fellowship - Ecosystem Services: Terrestrial Systems Soil and Plant Ecology
Dissolved organic nitrogen (DON) is an important part of the total dissolved nitrogen (TDN) loads of waterways throughout the United States; however, most of the impacts and monitoring of nitrogen have centered around dissolved inorganic nitrogen (DIN) in the form of nitrate. To better understand and predict the effect that terrestrial systems can have on DON levels in waterways, there is a critical need to understand the transport and transformations of organic nitrogen, DON and organic matter in both solid and aqueous forms in soils. This project will investigate the fundamental processes and drivers of DON delivery to waterways through the extensive tile-drained agricultural systems of the Upper Midwest. The primary objectives are to determine how different fractions of the bulk DON pool change as they move from residue layer leachate to surface flow in agricultural landscapes, and the spatial scale at which in-stream processes become more important than upland export of DON to surface waters.Approach:
This project will monitor chemical changes in the DON pool in agricultural soils and associated waterways both spatially and temporally over a multi-year period. Additionally, investigation into the long-term rates of production of new mineral surfaces and the extent of mineral occlusion by organic matter-which affects physical adsorption and DON export in tile-drained landscapeswill allow a better determination of transport rates for DON. Lastly, to determine the spatial scale at which in-stream processes become more important than the upland export of DON, seasonal changes in DON and TDN in successively larger downstream waterways will be monitored.Expected Results:
This research will contribute to a holistic understanding of water quality in intensively managed landscapes as it will focus on the organic portion of the TDN load, which is often overlooked but is greatly affected by the plant-soil system. Furthermore, it will provide a foundation for fully integrating the connections between physical and biological processes in upland and aquatic environments and how those processes can either enhance or detract from downstream surface water quality.
Potential to Further Environmental/ Human Health Protection
This project is expected to result in a unique perspective and a new, more fundamental understanding of DON export from terrestrial to aquatic systems-particularly those where the hydrology and soils have been radically altered by human activity-which will lead to better modeling and interpretation of data increasingly collected by many agencies that monitor DON and TDN in waterways. This is critical in many rural areas that are dependent on surface waters for primary water supply or drought contingency planning. Many of these areas are dependent on rural water networks, which provide waters that have a large array of end-uses, making holistic perspectives on water source quality a critical priority.Supplemental Keywords:
dissolved organic nitrogen, organic matter, mineral weathering, soil, water quality