1High Resolution In Situ Study

of Nutrient Loading and Estuarine Response in the

Columbia River

Observation ● Prediction ● Analysis ● Collaboration

www.stccmop.org

Melissa GilbertNeedoba, J. A.

Koch, C. Barnard, A. Baptista, A.

Acknowledgements:

Needoba/Peterson LabCMOP Staff

CMOP Astoria Field Team

2Columbia River

Washington

Pacific Ocean

OregonSATURN-

03

SATURN-05

River

Lower Estuary

RM-17

Upper Estuary

3The Study (Summer 2010) - Hypothesis

DenitrificationDecrease in nitrate

RemineralizationIncrease in ammoniumIncrease in phosphate

Estuary River

4

The Columbia River supplies excess nitrate to the estuary

all year

Seasonal Variability in the Columbia River

SUNA Nitrate Sensor at SATURN-05

403020100

Nitra

te (µ

M)

7/1/2009 10/1/2009 1/1/2010 4/1/2010 7/1/2010

Date

0.6

0.4

0.2

0.0

Ph

osp

ha

te (

µM

)

120100

80604020

0

N/P

Ra

tio

40

30

20

10

0

Nitr

ate

(µ

M)

7/1/2009 10/1/2009 1/1/2010 4/1/2010 7/1/2010

Date

24.8

5

40

30

20

10

0

Nitrate (µ

M)

AP

NA

11/1/2009 2/1/2010 5/1/2010 8/1/2010 11/1/2010

Date

4.0

3.0

2.0

1.0

0.0

Pho

spha

te (

µM

)C

ycle

-PO

4Estuary Data

6

50

40

30

20

10

0

N/P

Rat

io

11/1/2009 2/1/2010 5/1/2010 8/1/2010 11/1/2010Date

N/P Ratios in the estuary

NO3-NPO4-P

7N/P Ratios in the Estuary

3210

Pho

sph

ate

(µ

M)

Cyc

le-P

O4

7/29/2010 8/2/2010 8/6/2010 8/10/2010 8/14/2010 8/18/2010

Date

403020100

Nitra

te (µ

M)

AP

NA

20

15

10

5

0

N/P

Ra

tio

2.0

1.0

0.0

Tid

alH

eig

ht

(m)

8

30

25

20

15

10

5

0

Nitr

ate

(µM

)

302520151050Salinity

Ebb Tide7/30/20101600-2200

y = 0.88*x+1.71

R2 = 0.9978

30252015105

Sal

inity

12:00 AM7/30/2010

12:00 PM 12:00 AM7/31/2010

12:00 PM

Date

403020100

Nitrate (µ

M)

2.0

1.0

0.0

Tidal H

eight (m)

Calculating End Member Concentrations

SATURN-03

Salinity 32.4 = ocean end

member nitrate concentration

Intercept = River end member nitrate

concentration

9

30252015105

Sal

inity

12:00 AM7/30/2010

12:00 PM 12:00 AM7/31/2010

12:00 PM

Date

3

2

1

0

Phosphate (µ

M)

2.0

1.0

0.0

Tidal H

eight (m)

Calculating End Member Concentrations

SATURN-03

Salinity 32.4 = ocean end

member nitrate concentration

Intercept = River end member nitrate

concentration

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Pho

sph

ate

(µ

M)

302520151050

Salinity

Ebb Tide7/30/20101600-2200

y = 0.048*x+0.8575

R2 = 0.9907

10Calculating End Member N/P Ratios

N/P Ratio of River End Member = 6.4

20

15

10

5

0

N/P

Ra

tio

7/31/2010 8/4/2010 8/8/2010 8/12/2010 8/16/2010

Date

210-1

Tid

al H

eig

ht (m

)

Estuary Ocean River

11The Study (Summer 2010) - Hypothesis

DenitrificationDecrease in nitrate

RemineralizationIncrease in ammoniumIncrease in phosphate

Estuary River

12Denitrification ?

Average nitrate loss of 1.3 μM

12

10

8

6

4

2

0

Nitr

ate

(µM

)

7/28/2010 8/2/2010 8/7/2010 8/12/2010 8/17/2010

Date (Estuary End Member)

7/27/2010 8/1/2010 8/6/2010 8/11/2010 8/16/2010

Date (River Data)

Estuary End Member River Data

13Remineralization ?

Gain of 0.4 μM Phosphate

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Pho

spha

te (

µM

)

7/28/2010 8/1/2010 8/5/2010 8/9/2010 8/13/2010 8/17/2010

Date (Estuary End Member)

7/27/2010 7/31/2010 8/4/2010 8/8/2010 8/12/2010 8/16/2010

Date (River Data)

Estuary End Member Phosphate River Data

(predicted based on river nitrate and N/P)

14

60

50

40

30

20

10

0

Am

mon

ium

(µ

M)

7/28/2010 8/1/2010 8/5/2010 8/9/2010 8/13/2010 8/17/2010

Date

Remineralization ?

6.4-

15The Study - Results

DenitrificationDecrease in nitrate

Estuary River

RemineralizationIncrease in ammoniumIncrease in phosphate

16

2520151050

Salinity

y = (0.31 ± 0.04) * x + (2.76 ± 0.38)

R2

= 0.7796

16

14

12

10

8

6

4

2

0

Am

mon

ium

(µ

M)

2520151050

Salinity

y = (0.20 ± 0.015) * x + (1.6 ± 0.24)

R2

= 0.9457

RM-172.0

1.5

1.0

0.5

0.0

Pho

spha

te (

µM

)

y = (0.028 ± 0.004) * x + (0.16 ± 0.06)

R2

= 0.8456

y = (0.04 ± 0.003) * x + (0.21 ± 0.02)

R2

= 0.9153

•Phosphate: Lower at RM- 17 than at SATURN-03•PO4 @ BAT = 0.14

•Higher river NH4 at RM-17 than at BAT but not as high as SATURN-03

•NH4 @ BAT = 0.34 μM

Remineralization or particle attachment?

17The Study - Results

DenitrificationDecrease in nitrate

Estuary River

RemineralizationIncrease in ammoniumIncrease in phosphate

18Conclusions

• Lower NO3-N/PO4-P ratios in the estuary than the river• Transport through fresh water marshes decrease nitrate by 25%,

increase phosphate 3X and increase ammonium 50X. • During summer months MORE reactive N may be leaving the

Columbia River and estuary in the form of ammonium than in nitrate

• The Columbia River and estuary may not remove large quantities of anthropogenic nitrate via denitrification during the summer months

High resolution in situ nutrient data yields evidence for an overwhelming

remineralization signal in the Columbia River during the summer

High resolution in situ nutrient data yields evidence for an overwhelming

remineralization signal in the Columbia River during the summer

19Acknowledgments and Funding SourcesOHSU/CMOP Advisor:

Joseph Needoba

CMOP Director: Antonio Baptista

Needoba LabFlorian MoellerMichelle Maier

Ezra-Mel Pasikatan

CMOP Staff:Charles Seaton

Paul TurnerSarah Riseman

Grant Law

CMOP Astoria Field Team: Michael WilkinKatie Rathmall

Greta Klungness

WetLabs:Corey Koch

Andrew Barnard

SubChem Systems Inc.