1

Chemical and Physical Analysis of the Cape Fear

Estuary

The Cape Fear River

• The Cape Fear River (CFR), the most industrialized of all North Carolina’s rivers, winds for over 200 miles through the heart of the piedmont, crosses the coastal plains, and empties into the Atlantic Ocean just south of us near Southport.

What we measured

• Meteorology• Flow• Temperature• Salinity• Turbidity• Light Attenuation

• Chlorophyll • Dissolved Organic

Carbon• Dissolved Oxygen• pH• Nutrients

0M183.54M239.89M35

13.79M4217.24M5421.02M6124.54HB

Miles from seaStation

2

Raymond Gephart

• MS Chemistry

Turbidity/Meteorology

Turbidity meter

October Winds

0

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18

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Day

Win

d Sp

eed

(mph

)

September Winds

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1 3 5 7 9 11 13 15 17 19 21 23 25 27 29

Day

Win

d Sp

eed

(mph

)

*

*

October Precipitation

00.20.40.60.8

11.21.41.61.8

2

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Day

Pre

cipi

tatio

n (in

ches

)

September Precipitation

00.20.40.60.8

11.21.41.61.8

2

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29

Day

Pre

cipi

tatio

n (in

ches

)

*

*

* = cruise

^ = trace precipitation

^ ^

^ ^

^

Turbidity - Cruise 1

0

50

100

150

200

250

M18 M23 M35 M42 M54 M63 HBStation

Turb

idity

(ntu

)

SurfaceDeep

3

Turbidity - Cruise 2

0

50

100

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200

250

M18 M23 M35 M42 M54 M63 HBStation

Turb

idity

(ntu

)

SurfaceDeep

Surface Turbidity

0

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140

M18 M23 M35 M42 M54 M63 HB

Station

Turb

idity

(ntu

)

20042002-2003 Average

Deep Turbidity

0

20

40

60

80

100

120

140

M18 M23 M35 M42 M54 M63 HB

Station

Turb

idity

(ntu

)

20042002-2003 Average

Conclusions

• Cruise 1 had higher turbidity than Cruise 2 which could be a result of the faster winds and greater precipitation before the cruises.

• The deep turbidity was higher than the surface turbidity.

• This year’s turbidity was higher, especially for the deep water, than the average from the past couple years.

CTD Data • The CTD measures temperature, conductivity and pressure.

• The salinity was calculated from the temperature and conductivity measurements, using the practical salinity scale from 1978.

4

• Water Temperature: Temperature is a good example of thermal stratification within the water column. High water temperatures (35 degrees Centigrade and above) can be harmful to the aquatic life.

• Salinity: This is a good indicator of the vertical stratification within the water column. It also depicts any fresh water runoff as well as the tidal penetration of seawater.

0 4 10 13 17 21

0

1

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9

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11

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13

Distance (miles)

Depth (m)

Salinity Data Cruise 1

30-35

25-30

20-25

15-20

10-15

5-10

0-5

0 4 10 13 17 21 24

0

1

2

3

4

5

6

7

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9

10

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12

13Salinity

Distance (miles)

Depth (meters)

Salinity Data Cruise 2

30-35

25-30

20-25

15-20

10-15

5-10

0-5

0 4 10 13 17 21

012345678910111213

Distance (miles)

Depth (meters)

Temperature Data Cruise 1

25-25.524.5-2524-24.523.5-2423-23.522.5-2322-22.521.5-2221-21.520.5-2120-20.519.5-20

0 4 10 13 17 21 24

0

2

4

6

8

10

12

Distance (miles)

Depth (meters)

Temperature Data Cruise 2

25.00-25.5024.50-25.0024.00-24.5023.50-24.0023.00-23.5022.50-23.0022.00-22.5021.50-22.0021.00-21.5020.50-21.0020.00-20.5019.50-20.00

Stow Away Tidbit Temp Logger

• Eulerian measurement of temperature• Deployed at mid-depth from 9/20/04-10/25/04• Lat. 34°05.47N, Long. 77°55.93W• Captured

temperature data at 15 minute intervals

5

Daily Temp Flux

21

21.5

22

22.5

23

23.5

24

24.5

9/21/2

004 0

:03

9/21/2

004 1

:18

9/21/2

004 2

:33

9/21/2

004 3

:48

9/21/2

004 5

:03

9/21/2

004 6

:18

9/21/2

004 7

:33

9/21/2

004 8

:48

9/21/2

004 1

0:03

9/21/2

004 1

1:18

9/21/2

004 1

2:33

9/21/2

004 1

3:48

9/21/2

004 1

5:03

9/21/2

004 1

6:18

9/21/2

004 1

7:33

9/21/2

004 1

8:48

9/21/2

004 2

0:03

9/21/2

004 2

1:18

9/21/2

004 2

2:33

9/21/2

004 2

3:48

Time

Tem

p

Daily Temp Changes

12

13

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27

9/21/2

004

9/23/2

004

9/25/2

004

9/27/2

004

9/29/2

004

10/1/

2004

10/3/

2004

10/5/

2004

10/7/

2004

10/9/

2004

10/11

/2004

10/13

/2004

10/15

/2004

10/17

/2004

10/19

/2004

10/21

/2004

10/23

/2004

Date

Tem

p

Min

Max

Ave

daily AVG of Air Temperature

Average Temp

20

21

22

23

24

25

26

27

28

2002 LCFRP (5yr ave) 2004

Tem

p

Sept Oct

Conclusions• Temperature changes with tides under

stratified conditions

• Daily flux with air temperatures

• September 2004 cooler than previous years possibly due to storm events involving rain and high winds leading to evaporative cooling

ADCPAcoustic Doppler Current Profiler

• Measures velocity based on Doppler shifting of the sound scatter of particles in the water

• Assumes particles move at same velocity as the water

• Averages velocities of regularly spaced depth cells

6

Discharge

• Calculated by integrating the flow across the section of the river

Q = integral (v dx dz)

10-25-04 Data

Coastal Ocean Research and Monitoring Program (CORMP) http://152.20.21.7/stream.php

0 . 0 0

5 0 0 0 . 0 0

10 0 0 0 . 0 015 0 0 0 . 0 0

2 0 0 0 0 . 0 0

2 5 0 0 0 . 0 0

3 0 0 0 0 . 0 03 5 0 0 0 . 0 0

4 0 0 0 0 . 0 0

4 5 0 0 0 . 0 0

9/1/04

9/7/04

9/13/0

4

9/19/0

4

9/25/0

4

10/1/

04

10/7/

04

10/13

/04

10/19

/04

10/25

/04

10/31

/04

Dis

char

ge (f

t3/s

)CORMP Cruise#2

Cape Fear River Discharge at the Mouth

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

1999 2000 2001 2002 2003 2004

Dis

char

ge (f

t3 /s)

Sept

Oct

Coastal Ocean Research and Monitoring Program (CORMP) http://152.20.21.7/stream.php

Conclusions

• Uniform velocity with depth

• Discharge varies with rain events

• Higher tidal discharge due to base flow + freshwater inputs

7

pH

Why Measure pH– Fundamental solution property– Useful in Characterization– Has direct impact on chemical and biological

properties

How Measure pH

• Measure using a pH meter

• Typical pH: Fresh H2O = 5.5-7.0Salt H2O = 7.8-8.2

• On the cruises the pH was between 6.45 and 8.06

Cruise 1

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 5 10 15 20Salinity

[H+]

(uM

)

Cruise 2

0

0.01

0.02

0.03

0.04

0.05

0.06

0 5 10 15 20 25 30 35

Salinity

[H+]

(uM

) 0

2

4

6

8

10

M18 M23 M35 M42 M54 M64 HBStation

pHSep-04

Oct-04

01,02,03 Average

Conclusion

• The differences between the pH:– Cruise 1 much lower pH than cruise 2 or

earlier data

• Why? Rainfall affecting salinity during first cruise– Just had rain from hurricane– Not much rain during October

Conclusion 2

• Salinity and pH were negatively correlated during cruise 2 and cruise 1 because as the salinity increases high pH seawater is added to the system

8

Dissolved Oxygen (DO)

• Why Measure DO– Important marker of biological activity– Easy measurement, allow for

characterization of H2O type and health

• How Measure DO– Measure using YSI

• In-Situ, lowered over side of boat

DO Controls• Biological Controls of DO

– Production from photosynthesis:• CO2+ H2O CH2O+ O2

– Utilization in respiration and oxidation• CH2+ O2 CO2+ H2O

• Physical Controls on DO:– Salinity, Temp., Dissolved Organic Carbon

(DOC)

Cruise 1

y = -0.0588x + 106.7R2 = 0.9151

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100

0 100 200 300 400 500 600 700 800 900 1000

DOC (uM C)

Per

cent

Oxy

gen

Satu

ratio

n(%

)

Cruise 2

y = -0.0309x + 89.275R2 = 0.8296

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100

0 200 400 600 800 1000 1200 1400

DOC (uM C)

Perc

ent O

xyge

n Sa

tura

tion

0

1

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4

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6

7

8

M18 M23 M35 M42 M54 M61 HBStation

DO

(mg/

L)2004 Cruise 12004 Cruise 201,02,03 Average

Conclusion

• DO is controlled by dissolved organic carbon content of Cape Fear – As DOC increases, % saturation decreases

• This is b/c much of the O2 is used up in oxidation of the added organic matter

Chlorophyll in the Cape Fear River

9

Introduction• Photosynthetic pigment

present in chloroplastsCO2 + H2O ↔ (CH2O) + O2

• Structure is a porphyrinring, which is the light absorbing portion

• In addition, there is a non polar phytal chain which anchors it to the cell membrane.

Importance

• Estimate of phytoplankton biomass

• Taxonomic distinction for algae based on distribution between different pigments

• 3 types of chlorophyll: a, b, and c• Each absorbs different wavelengths of

light

Methods

• Obtain water sample• Pass determined quantity through a filter• Freeze until further analysis

• Add acetone to extract chl a

• Measure fluorescence

QuestionsIs cruise 1 different than cruise 2?

0

2

4

6

8

HB m61 m54 m42 m35 m23 m18

Site Identification

Chl

orop

hyll

a C

once

ntra

tions

(ug/

L) Cruise 1 Top

Cruise 2 Top

0

2

4

6

8

HB m61 m54 m42 m35 m23 m18

Site Identification

Chl

orop

hyll

Con

cent

ratio

n(u

g/L) Cruise 1 Bottom

Cruise 2 Bottom

10

Is the top different than the bottom?

0

2

4

6

8

HB m61 m54 m42 m35 m23 m18

Site Identification

Chl

orph

yll a

Con

cent

ratio

n (u

g/L) Top Cruise 2

BottomCruise 2

0

2

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6

8

HB m61 m54 m42 m35 m23 m18

Site Identification

Chl

orop

hyll

a Con

cent

ratio

ns

(ug/

L) Top Cruise 1Bottom Cruise 1

Is there similarity to other years?

0

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16

HB m61 m54 m42 m35 m23 m18

2001

2002

2003

2004

Results• Greater chlorophyll levels measured at depth,

especially for Cruise 1

• Top values for Cruise 1 are lower than top for Cruise 2

• Bottom values for Cruise 1 are mostly greater than bottom for Cruise 2

• Data this year generally falls within range of other years. Although, scatter in data especially at end members.

Results

• Chlorophyll levels appear to be directly related to turbidity levels

• No relation to salinity levels

• No clear correlation with nutrient levels or light penetration (Kd)

Chlorophyll vs. Turbidity

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8

Chlorophyll a Concentration (ug/L)

Turb

idity

(NTU

)

Conclusions• The Cape Fear River is a very dark river, therefore,

expect to see low chlorophyll levels

• Chlorophyll data ranged from 0.88 to 6.80 ug/L. Normal chlorophyll values for the Cape Fear ranges from 0.7-15 ug/L

• Chlorophyll in the Cape Fear system is directly related to turbidity

• It is suggested that the Cape Fear River has low chlorophyll levels because it is a light limited system

11

Dissolved Organic Carbon

Dissolved Organic Matter (DOM)

– CDOM: chromophoric dissolved organic matter– DON: dissolved organic nitrogen– DOC: dissolved organic carbon– TDN(total dissolved N) =DON+DIN(dissolved inorganic N)

Sources of DOC

– River input (0.2*1015g C yr-1)– Atmospheric deposition (0.09*1015g C yr-1)– Porewater diffusion (0.02-0.17*1015 g C yr-1)– Biological production

• Sloppy feeding• Excretion and cell lysis• Release from fecal matter

Instrumentation

• DOC was measured using the high temperature catalytic oxidation (HTCO) method with NDIR detection on a Shimadzu TOC-5050A carbon analyzer.

• TDN will be calculated as the sum of DIN and DON, which will be measured with a linked Shimadzu TOC-5050/Antek 9000N system.

Methods

• Utilized high temperature catalytic oxidation (HTCO)

– Converts DOC into CO2 quantified IR– Converts TDN NOx + O3 NO2

*

• Chemiluminescent decay

Cruise 2 - DOC

0200400600800

1000

M18 M23 M35 M42 M54 M61 HB

Station

Con

cent

ratio

n(u

M) Surface

Bottom

Cruise 1 DOC

0

500

1000

1500

M18 M23 M35 M42 M54 M61 HB

Station

Con

cent

ratio

n(u

M)

Surface

Bottom

12

CFRP - DOC vs. Salinity

y = -27.6x + 1119R2 = 0.84

0

500

1000

1500

2000

0 5 10 15 20 25 30 35Salinity

Con

cent

ratio

n (u

M)

Cruise 2 - DOC vs. Salinity

y = -29.016x + 1141.1R2 = 0.9633

0250500750

1000

0 10 20 30

Salinity

Con

cent

ratio

n(u

M)

Surface

Bottom

Cruise 1 - DOC vs. Salinity

y = -33.575x + 1172.1R2 = 0.9678

0

500

1000

1500

0 10 20 30 40

Salinity

Con

cent

ratio

n(u

M)

Bottom

Surface

Linear(Series3)

Cruise 1 - TDN vs. Salinity

y = -1.6826x + 78.81R2 = 0.9667

020406080

100

0 10 20 30 40

Salinity

Con

cent

ratio

n(u

M)

Cruise 2: TDN vs. salinity

y = -2.3343x + 93.547R2 = 0.8618

020406080

100

0 10 20 30 40Salinity

conc

entr

atio

n(u

M)

Conclusions

• DOC surface concentrations were significantly higher than past years

• DOC with respect to salinity showed conservative mixing, consistent with historical data

• TDN values were analogous with past years for lower CFRP

Nutrient Distribution In the Lower Cape Fear River

Stephen GillMS Marine ScienceUniversity of North Carolina at Wilmington601 South College Road,Wilmington, NC, 28403

Nutrient assay Process

Surface and Bottom sample

Filter

Refrigerate

Continuous Flow Analysis

Nitrate

Phosphate

Ammonium

Long term comparisons.Nitrite + Nitrate concentration in the Lower Cape Fear River (1997-2004)

0

50

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150

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M18 M23 M35 M42 M54 M61 HB

Station

Nut

rient

con

cent

ratio

n (u

g/

LCFRP 1997-2003UNCW 2003-204UNCW 2004

13

Physical Controls - Conservative mixing

Nitrate + Nitrite concentrations with respect to salinity in the lower Cape Fear River.

y = -1.3522x + 44.063R2 = 0.9946

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35

Salinity

NN

con

cent

ratio

n (u

mol

/l)

Oct. surfaceOct. bottom

Nov. surfaceNov. bottom

Linear (Nov. surface)

Physical Controls Physical Controls -- Conservative mixingConservative mixingPhosphate concentrations with respect to Salinity in the Lower Cape Fear River.

y = -0.0564x + 1.8996R2 = 0.9968

0

0.5

1

1.5

2

2.5

3

3.5

0 5 10 15 20 25 30 35

Salinity

P co

ncen

trat

ion

(um

ol/l)

Oct. surfaceOct. bottom

Nov. surfaceNov. bottom

Linear (Nov. surface)

Physical Controls - Conservative mixing

Ammonium concentrations with respect to saliniy in the Lower Cape Fear River

0

2

4

6

8

10

12

14

0 5 10 15 20 25 30 35

Salinity

P co

ncen

tratio

n (u

mol

/l

Oct. surfaceOct. bottomNov. surface

Nov. bottom

Cruise 1Nutrient concentration in the Lower Cape Fear River (Oct. 2004).

0

2

4

6

8

10

12

14

16

18

M18 M23 M35 M42 M54 M61 HB

Station

Nut

rient

con

cent

ratio

n (u

mol

/l)

N+N surfaceN+N bottomP surface

P bottomA surfaceA bottom

Cruise 2Nutrient concentration in the Lower Cape Fear River (Nov 2004).

0

5

10

15

20

25

30

35

40

M18 M23 M35 M42 M54 M61 HB

Station

Nut

rient

con

cent

ratio

n (u

mol

/l)

N+N surfaceN+N bottomP surface

P bottomA surfaceA bottom

Conclusions• Cruise Averages consistent with long term

data.

• Individual cruises highly variable (Analogous to seasonality).

• Nutrient distribution explained in terms of salinity.

• Nutrient peaks correlate to turbidity maxima.

14

Light Attenuation in the Cape Fear River

Jeremy Pealer

What are we measuring?• Photosynthetically active radiation (PAR)• 400-700nm• Utilized in photosynthesis by

phytoplankton

Licor Radiometer

• Measures PAR at specified depth

• Compare to surface PAR to get Kd

• Kd measures light attenuation rate as a function of depth

• Increase depth, decrease PAR

Light Attenuation:Cape Fear River Estuary

M18 Light Attenuation: Cruise 2

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 20 40 60 80 100

PAR Irradiance

Dept

h (m

)

Series1Expon. (Series1)

M61 Light Attenuation: Cruise 2

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 50 100

PAR Irradience

Dep

th (m

)

Series 1Expon. (Series 1)

What are controls?

• Ez = E0 e-Kd z (where Ez is irradiance at depth z and E0 is irradiance just below the surface)

• Depth• Light is absorbed or scattered• Turbidity• Dissolved organic matter (CDOM)

• Kd = Kd water + Kd turbidity + Kd CDOM

Estuarine Turbidity

Turbidity Trends

01020304050

M18 M23 M35 M42 M54 M61 HB

Station

Turb

idity

(NTU

)

Cruise 1Cruise 2LCFRP 2003

15

Kd Trends in the Estuary

Light Attenuation Coefficients

0

2

4

6

8

M18 M23 M35 M42 M54 M61 HBStations

k (1

/m) Cruise 1

Cruise 2LCFRP 2003

Light Attenuation:The Effects of DOC and Turbidity

Kd versus Turbidity

y = 0.0604x + 1.1397R2 = 0.3141

012345678

0 20 40 60 80 100 120 140Turbidity (NTU)

Kd

(1/m

)

2004 Cr 12004 Cr 2LCFRP avg

Kd versus DOC

y = 0.0018x + 0.8424R2 = 0.8268

y = 0.0036x + 2.062R2 = 0.5519

012345678

0 200 400 600 800 1000 1200 1400

DOC (µM C)

Kd

(1/m

)

2004 Cr 12004 Cr 22001 + 2002

Conclusions

• Kd values similar in Cruise 2 and CFRP• Estuary turbidity values lower than in

2003• DOC major contributing factor • Turbidity minor contributing factor