In–stream nitrogen processing in urban degraded and restored streams in Baltimore, MD

1. In–stream nitrogen processing in urban degraded and restored streams in Baltimore, MD Carolyn A. Klocker (UMCES) Sujay Kaushal (UMCES), Peter Groffman (IES), and Paul Mayer (EPA) BES Annual Meeting 10/19/06

2. Nitrogen retention and removal in streams • Nitrogen being retained and removed in both small headwater streams (Peterson et al 2001) and larger rivers ≥ 5th order (Seitzinger et al 2002) • Nitrogen retention or removal = Inputs - Outputs • Includes biotic uptake, retention in sediments and denitrification

3. Stream Degradation Nutrient inputs Removal of riparian zone Bank Incision Sediment inputs Increased Nitrogen Concentrations Lateral movement of stream channel

4. Stream Restoration Bank re-shaping Channel manipulation Re-vegetation Rip Rap Erosion control Substrate manipulation Cross Vane

5. Objective • To determine the nitrogen retention ability of 4 urban streams, 2 restored and 2 degraded, using the metrics of nutrient spiraling theory. • uptake length, uptake rate, and uptake velocity • To compare these values to known literature values recently reported

6. Nutrient spiraling theory NO3 http://limnology.wisc.edu/courses/zoo548/Nutrient%20spiraling_handout.pdf

7. Retention Parameters • Uptake length • Sw = Q C U w • Uptake rate • U = vf C • Uptake velocity • vf= Q Sw w Q = discharge C = concentration of nutrient w = stream width (Stream Solute Workshop 1990)

8. Nutrient additions • Goals • To add a solution increasing the nutrient in question (NO3-) and a conservative tracer (Br-) • Allow the concentrations to reach plateau • Uptake length = the inverse slope of the regression of the ln (corrected concentration) of NO3- verses distance downstream

9. Restoration Sites • Minebank Run • 2nd order stream • Upstream reach restored in 1998 and 1999 • Goal of the restoration was to improve the geomorphic stability of the stream bed and reduce incision

10. Spring Branch • 1st order stream • Loch Raven Watershed • Drains directly into the Loch Raven Reservoir • Restoration 1994 - 1997 • Goal of the restoration was to manage the flow of the stream to control for erosion and floods

11. Degraded Sites • Glyndon • 1st order stream • BES LTER stream • Gwynn Falls Watershed • Visible channel incision • Little riparian buffer • Analytical problems • Interference with Bromide

12. DR 5 • Headwater tributary of the larger 3rd order Dead Run • Gwynn Falls Watershed • Little riparian buffer • Visible channel incision

13. Methods • NO3- and Br- added for approximately 8-10 hrs at 45 mL/min • 5 sampling locations • Collected approx. every 30 minutes • Samples were filtered, frozen and analyzed using a dx 500 Ion Chromatograph A B I C D E

14. Results

15. Results

16. 800 to 16400 (Grimm 2005, Gucker and Pusch 2006)

17. As restoration projects age the may be able to retain nitrogen more efficiently Need to look at more than just the state of the stream Watershed characteristics DOC Periphyton densities and chlorophyll a Geomorphic structures Implications and Future Directions

18. Data to be analyzed • Isotope additions • Maintain ambient nutrient concentrations • In situ denitrification rates • 2 completed at Minebank Run in August 2006 • Denitrification Enzyme Assays (DEA) • Conducted at all 4 sites in late June to early July of 2006

19. Acknowledgements • Sujay Kaushal, Paul Mayer, and Peter Groffman • Pete Bogush and Tammy Newcomer • Dan Dillon, Ho-Jin Kim Paul Lilly and Melanie Harrison • Katie Kline and Keith Eshleman • EPA and AL

20. Decreased Nitrogen Concentrations ???? Restored Urban Stream: Developed Stage Healthy riparian zones Increased organic matter