Nitrogen source tracing in the Choptank River Watershed Midshore Riverkeeper Conservancy University...

Nitrogen source tracing in the Choptank River Watershed

Midshore Riverkeeper ConservancyUniversity of Maryland Center for Environmental Science

National Fish and Wildlife Foundation

Forms of Nitrogen

N2

N stable isotopes: how it works

++ +

++

+

+

-

-

-

--

- -

++ +

++

+

+

-

-

-

--

- -

The 15N:14N ratio can vary depending on how nitrogen is used

15N

14N

Ratio referred to as d15N

Amount of nitrogen (%N) does not equal d15N

%Nd15N

%Nd15N

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Nitrogen CycleAtmospheric

nitrogenAtmospheric

fixation


nitrogenAtmospheric

fixation

Biological fixation


nitrogenAtmospheric

fixation

Industrialfixation

Biological fixation


nitrogenAtmospheric

fixation

VolatilizationIndustrialfixation

Biological fixation


nitrogenAtmospheric

fixation

Denitrification

Ammonium

Nitrite

Nitrate

VolatilizationIndustrialfixation

Biological fixation

% Nitrogen

d15

N

0 5

0

30

-5

5

10

15

20

25

1 2 3 4

DenitrificationAnimal Waste

Volatilization enrichment

Fertilizer sourceLow nitrogen and activity

Objectives

• Delineate the nitrogen contribution of different activities in the Choptank River Watershed (e.g. poultry, dairy, sewage, cropping, sod, slaughterhouse)

• Adopt combination of water quality and nitrogen stable isotope composition in aquatic plants and water samples.

• Relate findings to land-use practices

• Identify focus areas for further work / targeting of management activities

Sampling Sites

Easton STP

Cambridge STP

Denton STPCordova

Oakland Farm

Colliers Farm

What we collected• Phragmites along Choptank River – d15N– %N

• Grasses in Choptank watershed– d15N– %N

• Water quality– MRC– This project

Sample analysis

Denitrification Animal WasteVolatilization enrichment

Fertilizer sourceLow nitrogen and activity

1.0 2.0 3.0 4.0 5.00

2

4

6

8

10

12

14

16

18

20

%N vs. DelN

% Nitrogen

Delta

15N

Results

1.0 2.0 3.0 4.0 5.00

2

4

6

8

10

12

14

16

18

20

%N vs. DelN

% Nitrogen

Delta

15N


Fertilizer sourceLow nutrients and activity

RiverWatershed

Results

2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.40

2

4

6

8

10

12

14

16

18

20

%N vs. DelN - River

% Nitrogen

Delta

15N



OppositeCambridge STP

Denton

TuckahoeR.

HuntingtonCk.

GaineysWharf

ChoptankAbove Tuckahoe Easton

STP

Results

1.0 2.0 3.0 4.0 5.00

2

4

6

8

10

12

14

16

18

20

%N vs. DelN - Watershed

% Nitrogen

Delta

15N



Oakland(corn – unirrigated /manure)

Oakland(corn - irrigated)

OaklandSpray irrigated dairy

Cordova Ck Trib(poultry, manure, slaughterhouse)

Oakland(pond grass)Oakland

(manure)

Cordova Ck Trib (DownstreamPoultry)

Colliers(corn – chicken manure)

Cordova Ck(downstream slaughterhouse)

Masons Branch Trib.Upstream poultry

Masons Branch Trib.Downstream poultry

Results

10 15 20 25 30 35 40 45 50 555

6

7

8

9

10

11

2

3

4

5

DelN%N

Distance up-river (miles)

Del

ta 1

5N

% N

Tuckahoe

Results

0 10 20 30 40 50 600.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0.00

0.50

1.00

1.50

2.00

2.50

%N vs TN - River

%NMean TN

AMTD

%N TN

Tuckahoe

Results

Results

2 3 4 50

2

4

6

8

10

12

14

16

18

20

%N vs. DelN - River 2003 vs 2013

20032013

% Nitrogen

Delta

15N



Results

0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.400.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

R² = 0.852861556358753

TN vs TP - Water River

TN (mg/L)

TP (m

g/L)

Oakland Pond Cordova CkDown. Slaughterhouse

Cordova CkDown. Poultry

Cordova Ck Trib(poultry, manure, slaughterhouse)

Masons Branch Trib.Upstream poultry

Masons Branch Trib.Downstream poultry

Results

5 6 7 8 9 10 11 120.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

R² = 0.579815748575481

TN vs TP - Water Watershed

TN

TP

Results

5 6 7 8 9 10 11 120.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

R² = 0.579815748575481

R² = 0TN vs TP

TN

TP

River Watershed

Watershed is distinct whereas river is a mixing bowl

Summary

• Demonstrated the river is sink of varied catchment activities

• Management needs to target N and P separately. Make sure any nutrient removal process targets the relevant nutrient.

• Emphasis on poultry appears to be P and not N

• Unclear why %N is inverse of TN in the river

• Shift over the past 10 years in N influence in the Choptank from animal waste to mixed animal waste/fertilizer source.

Next steps…

• Follow up on the turf farm• Investigate above Denton and below Cambridge• Consult with other scientists about the inverse

relationship with TN and %N (water problem is deposited downstream in the mud???)

Results

15 20 25 30 35 40 45 50 555

6

7

8

9

10

11

DelN 2003 vs 2013

DelN 2003DelN 2013

Distance upriver (miles)

DelN

(ppt

)

fix

Results

15 20 25 30 35 40 45 50 552

3

4

5

%N 2003 vs 2013

%N 2003%N 2013

fix

Nitrogen source tracing in the Choptank River Watershed Midshore Riverkeeper Conservancy University...

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