Using stable dN15 ratios to help differentiate nitrogen sources within a residential community- another tool for the TMDL toolbox.

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Using stable dN15 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

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stable dN15 ratios help differentiate nitrogen
sources

• Ratio is based on heavy and light form of N
• In general according to the literature
• dN15 between 2.00 and 8 is from atmospheric
• dN15 between -4.00 and 4.00 is from fertilizer
• dN15 between 18.00 and 22.00 is from humans

• d15N 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 d15N
  around 0- 4 0/00 (parts per thousand) (Heaton,
  1986), while Nitrogen from septic systems and
  animal waste has a d15N from 8 to 22 0/00.
  (Heaton, 1986). Levels of d 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 d15N ratios as
  you move toward meat-eating consumers in the
  food web.

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San Carlos Park
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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.

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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

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Winged Foot/Oriole

• Delta N 15
• Duckweed (March) 0.86, 3.67
• Duckweed (Sept) 3.13 2.83
• Extract flock (Sept) 1.87

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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

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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

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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

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Laurel Valley/New Jersey

• Delta N 15 (Sept)
• Flock 5.07
• Lettuce leaves 0.93
• Lettuce roots -0.98
• Extract flock 5.62

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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

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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

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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

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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

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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

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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

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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
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Golf Course Effluent

• Delta N 15
• Sediment Flock
• March 17.84
• Sept 17.80 19.46 17.68 16.79

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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

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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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