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Goal 1 - Characterize the spatial and temporal distribution and co-occurrence of Pseudo-nitzschia sp., domoic acid, urea, and other water quality parameters in relation to surrounding land use to identify probable terrestrial sources of urea in the Manokin River watershed. <BR>Objective 1 - In tidal waters of the Manokin River watershed, determine the spatial and temporal distribution and co-occurrence of Pseudo-nitzschia sp., domoic acid, urea, and other water quality parameters (Eric May, MS student). <BR>Objective 2 - In the Manokin River, its tributaries, and drainage ditches, examine in-stream processes that influence the downstream movement and fate of urea (Anthony Buda, Elizabeth Boyer). <BR>Objective 3 - Identify sources and processes that govern urea export in the Manokin River watershed (Anthony Buda, Elizabeth Boyer, Ph.D. student). <P>Goal 2 - Determine the effects of agricultural practices on the concentration and distribution of urea entering the surface waters of the Manokin River watershed. <BR>Objective 1 - Examine existing records and conduct surveys to characterize land applications of commercial urea fertilizer and manure in the Manokin River watershed (Arthur Allen, Josh McGrath). <BR>Objective 2 - Using laboratory experiments to determine the concentration and persistence of soluble urea derived from agricultural fertilizers and manures (Ray Bryant, Peter Kleinman, Ph.D. student). <BR>Objective 3 - Using field studies, characterize urea transport through surface water runoff and subsurface water movement to the Manokin River system (Ray Bryant, Peter Kleinman, Anthony Buda, Arthur Allen). <P>Goal 3 - Provide educational opportunities to undergraduate and graduate students. <BR>Objective 1 - Develop sub-projects for use by undergraduate, masters, and doctoral students in pursuing their degrees (all). The products from this project will be as follows: 1. data describing the amount and degree of retention of urea in soils; 2. data describing the movement and fate of urea; 3. data describing the co-occurrence of urea and domoic acid; 4. data describing the species distribution and abundance of Pseudo-nitzschia sp.; 5. preliminary models that describe urea's movement and fate; 6. two masters theses; and 7. two doctoral dissertations. <P>The metrics for products 1 through 3 are the production of usable data for incorporation into preliminary models describing urea's movement and fate in the Manokin River system and for products 3 and 4 preliminary models describing the relationship between Pseudo-nitzschia sp., domoic acid and urea. Metrics for the theses and dissertations is the timely completion of the student's degrees. <P>Outcomes for the project are expected to give a better understanding of the consequence of shifting from traditional sources of fertilizer to the use of urea and from the continued reliance on poultry litter. The desired ultimate outcome is that once processes are clearly understood, alternative approaches to how fertilizers are applied can be developed to minimize any environmental impact. The role of the federal cooperator in this project has been outlined above, as have the roles of the other federal and university cooperators.
Non-Technical Summary: Worldwide production of ammonium nitrate and anhydrous ammonia has decreased significantly in the years following the bombing of the Oklahoma Federal Building. To ensure continued availability of nitrogen as fertilizer, a subsequent rise in the use of urea as an alternative has occurred. Recent reports in the United States from Monterey, Calif., and from other parts of the world have shown that the diatom Pseudo-nitzschia has been on the increase, and suggestions have been made that this could be in response to the increased use of urea, which has been found in many of the world's riverine systems. Pseudo-nitzschia is the algae responsible for the production of domoic acid, which is a potent neuro-toxin affecting memory and movement in humans and disorientation and behavior in mammals. This project is designed to link the application of urea fertilizer or chicken litter containing urea to the surface and subsurface movement of urea into rivers and streams; to determine the instream movement and fate of urea; to determine the distribution of Pseudo-nitzschia in tidal fresh and estuarine portions of the Manokin River system; to determine the concentrations of domoic acid in the Manokin River system; and to correlate the occurrence of domoic acid with diatom numbers and distribution, and to correlate the number and distribution of diatoms with the concentrations of urea in the system. Ultimately, the intent is to model the varying factors to determine the degree of risk associated with the use of urea or chicken litter as fertilizers. <P> Approach: The strategy of this project is to determine linkages between terrestrial sources of urea and domoic acid in the estuary by examining land use patterns in relation to urea concentrations in surface waters; monitoring agricultural activities in relation to urea concentrations in surface waters; characterizing the fate and transport of urea in surface runoff, drainage ditches, and streams; and quantifying the distribution and abundance of diatom species and the production of domoic acid in relation to urea concentration and other water quality parameters. Pseudo-nitzschia sp. Distribution and Abundance - Water samples for Pseudo-nitzschia will be collected from 25 selected sites throughout the Maryland Manokin River. For Pseudo-nitzschia sp. identification and enumeration, samples will be preserved using Lugol's solution for light microscopy, and 0.5 percent Gluteraldehyde for transmission electron microscopy. Domoic Acid and Urea Analyses - Samples for domoic acid analyses will be frozen. All samples will be analyzed for urea using recommended methods for a Lachat flow injection analyzer equipped with both a saline and a freshwater urea manifold. Sources and Delivery of Urea in Baseflow and Stormflow - Synoptic water sampling will be conducted throughout non-tidal portions of the Manokin River watershed to evaluate trends in urea concentrations with land-use, time of year, and hydrology. In-stream Processing and Fate of Urea - In-stream processing of urea will be evaluated experimentally using standard solute injection techniques. The technique has been widely used to study in-stream processing of nitrogen and phosphorus in flowing waters and recently has been used to study DON processing in small, undeveloped streams. Sources and Processes that Govern Urea Export - In an exploratory study, we will work with the SPAtially-Referenced Regression on Watershed (SPARROW) attributes model (Smith et al., 1997) to gain a better understanding of the importance of land-use and in-stream processing on urea export from the Manokin River watershed. Rainfall Simulation Studies - Experiments will be conducted to assess interactions between the soil, the nitrogen source, and the timing/sequence of urea losses in runoff using an established indoor runoff box protocol (National Phosphorus Research Project, 2001). Column Leaching Studies - Soil columns of 30-cm diameter and 50-cm depth will be collected following the method of Kleinman et al. (2005). Profiles of all soils will be described at each of the column sampling locations, and bulk samples from the center of major horizons will be collected for analysis. Urea Transport Through Surface Water Runoff and Subsurface Water Movement - Trials will be conducted at the UMES research farm in Princess Anne, Md., on a field with slope gradients ranging from 3 to 5 percent. Undergraduate and Graduate Student Training - A Ph.D. student's doctoral program will be based on the lysimeter and rainfall simulation studies. A UMES masters student will be involved in the field sampling for Pseudo-nitzschia sp., enumeration, the validation of species, and the reporting of results that will be used for the masters project.