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stable δ N 15 ratios help differentiate nitrogen sources

Using stable δ N 15 ratios to help differentiate nitrogen sources within a residential community- another tool for the TMDL toolbox.

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stable δ N 15 ratios help differentiate nitrogen sources

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  1. Using stable δN15 ratios to help differentiate nitrogen sources within a residential community- another tool for the TMDL toolbox. • Nora Egan Demers Associate Professor of Biology and Interdisciplinary StudiesFlorida Gulf Coast UniversityFt. Myers, Florida • Report to the Watershed Council • January 17, 2008

  2. Ratio is based on heavy and light form of N In general – according to the literature δN15between 2.00 and 8 is from atmospheric δN15between -4.00 and 4.00 is from fertilizer δN15between 18.00 and 22.00 is from humans δ15N =[R(sample)-R(standard)/R(standard)]*1000 where R= ratio of 15N/14N and R standard is the atmospheric standard. Generally, Nitrogen from fertilizers has an δ15N around 0+- 4 0/00 (parts per thousand) (Heaton, 1986), while Nitrogen from septic systems and animal waste has a δ15N from +8 to +22 0/00. (Heaton, 1986). Levels of δ 15N in atmospheric depositions are about +2 to +8.00 0/00 (Kreitler et al, 1978). This is because the lighter 14N isotope is preferentially fractionated during bacterial nitrification, resulting in higher δ15N ratios as you move toward meat-eating consumers in the food web. stable δN15 ratios help differentiate nitrogen sources

  3. San Carlos Park

  4. Lee County Utilities overlay showing sewer and water infrastructure for San Carlos Park, Lee County, Florida. Areas in green are served by municipal sewer and water, in blue by water, (with septic) and in red have well-water and septic systems.

  5. Winged Foot/Oriole (mg/L) 3/07 9/07 • Ammonia 0.871 0.453 • Nitrite 0.008 0.01 • Nitrate 0.01 0.01 • PO4 0.09 0.09 • TKN 62 5.9 • TN 62 5.9 • Total PO4 8.3 .59

  6. Winged Foot/Oriole Delta N 15 • Duckweed (March) 0.86, 3.67 • Duckweed (Sept) 3.13 2.83 • Extract flock (Sept) 1.87

  7. Kakareka (mg/L) March Sept • Ammonia 0.222 0.049 • Nitrite 0.008 0.004 • Nitrate 0.01 0.02 • PO4 0 0 • TKN 1.1 0.94 • TN 1.12 0.96 • Total PO4 0.046 0.027

  8. Kakareka Delta N 15 • Sediments leafy (March) 1.70 • Algae (March) 2.66 • Sediment flock (March) 2.50 2.38 • Roots (Sept) -0.90 -1.82 • Scrapings from leaves (Sept) -0.35

  9. Laurel Valley/New Jersey (mg/L) Sept • Ammonia 0.348 • Nitrite 0.007 • Nitrate 0.04 • PO4 0 • TKN 1.1 • TN 1.1 • Total PO4 0.022

  10. Laurel Valley/New Jersey Delta N 15 (Sept) Flock 5.07 Lettuce leaves 0.93 Lettuce roots -0.98 Extract flock 5.62

  11. Demers (mg/L) March Sept • Ammonia 0.042 0.315 • Nitrite 0.007 0.014 • Nitrate 0.02 0.06 • PO4 0.02 0 • TKN 1.8 0.94 • TN 1.83 1 • Total PO4 0.17 .0033

  12. Demers Sept. Floating blob: 4.68 6.02 Lettuce leaf 2.92 3.82 Lettuce roots 4.47 Sediment flock 5.79 Extract flock 4.34 4.95 2.92 Delta N 15 March floaty algae 4.08 leafy 4.15 Sediment 6.49 5.9

  13. Constitution (mg/L) March Sept • Ammonia 0.087 0.052 • Nitrite 0.008 0.006 • Nitrate 0.15 0.21 • PO4 0.01 0 • TKN 0.81 0.58 • TN 0.97 0.8 • Total PO4 0.084 0.018

  14. Constitution Delta N 15 Macroalgae (March) 8.72 Sediment flock (March) 6.39 Rinsed roots (Sept) 9.27 Sediment flock (Sept) 4.24 Extract flock (Sept) 5.37 5.32

  15. Outfall: 46B-9GR ( mg/L) March Sept. Ammonia 0.067 0.017 • Nitrite 0.008 0.004 • Nitrate 0.2 0.22 • PO4 0.01 0 • TKN 0.57 0.83 • TN 0.78 1.1 • Total PO4 0.026 .009

  16. Outfall: 46B-9GR Delta N 15 Green algae (March) 11.05 Brown macro algae (March) 8.51 Sediment flock (March) 10.65 Sept: Root ball rinsed 6.03 Algae 7.43 Sediment flock 5.77 Extract flock 7.35

  17. Golf Course Effluent (mg/L) March Sept • Ammonia 0.414 0.213 • Nitrite 0.178 0.098 • Nitrate 0.44 2.48 • PO4 0.67 .73 • TKN 2.4 2.3 • TN 3.02 4.8 • Total PO4 1.00 0.89 Average of 200,000 gallons per day of reclaimed water delivered to this lake

  18. Golf Course Effluent Delta N 15 Sediment Flock March 17.84 Sept 17.80 19.46 17.68 16.79

  19. Golf Course- Lake (mg/L) March Sept • Ammonia 0.2 0.105 • Nitrite 0.009 0.006 • Nitrate 0.01 0.09 • PO4 0.02 0 • TKN 1.8 2 • TN 1.82 2.1 • Total PO4 0.13 0.13

  20. Golf Course- Lake Delta N 15 March Sediment Flock 9.96 Sept scraping off leaves 6.98 5.05 Sediment flock 7.81 Extract flock 7.69

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