Sources of Oxygen Demand in the Lower San Joaquin River,

California

P. W. Lehman,

J. Sevier, J. Giulianotti & M. Johnson

California Department of Water Resources

StocktonAntioch

Sacramento

River

River

CALIFORNIA

38 00’ W

38 20’ W

Carquinez straight

122 20’ N 122 00’ N 121 40’ N 121 20’ N

Sa c ra

m

eo

San

San Francisco BayMossdale

Current situation:

There has been little change in dissolved oxygen concentration in

the channel despite enhanced management and a decrease in

phytoplankton biomass

0

10

20

30

40

50

60

70

80

90

100

Aug Oct Sep Nov Aug Oct

Per

cen

t

1970 -1979 1980 - 1989 1990 - 1999

Frequency of values below 5 mg l-1

0

10

20

30

40

50

60

70

80

70 75 80 85 90 95 2000

year

Rough and Ready Island

Ch

loro

ph

yll a

µg

l-1Chlorophyll a decreased over time in

the channel

Question:

What are the primary sources of oxygen demand in the Deep Water

Channel near Stockton?

Study Methods

biweekly or monthly sampling July - November 2000 & 2001

discrete variables: Primary productivity : in situ dissolved oxygen light and dark bottle technique Nutrient concentrations chlorophyll a and phaeophytin concentration BOD tests continuous variables

vertical profiles with YSI 6600 sonde continuous flow continuous water quality

STOCKTON

MC DONALD

MD

ROBERTS

ISLAND

ISLAND

Rough and Ready Island

Calaveras River

TB

CP

TC

RRL48San Joaquin River

Deep Water Channel

San Joaquin River

N

4 km

Middle River

VN

80o 00’ W

121o 20’ N

Water Treatment Plant

TC Turner CutRR Rough and Ready IslandL48 Navigation Light 48TB Turning BasinCP Channel PointMD MossdaleVN Vernalis

STOCKTON

MC DONALD

MD

ROBERTS

ISLAND

ISLAND

Rough and Ready Island

Calaveras River

TB

CP

TC

RRL48San Joaquin River

Deep Water Channel

San Joaquin River

N

4 km

NN

4 km

Middle River

VN

80o 00’ W

121o 20’ N

Water Treatment Plant

Findings

0

5

10

15

1-Jun 1-Jul 31-Jul 30-Aug 29-Sep 29-Oct

Date

mg

/L

2001

Dissolved oxygen in DWSC

0

5

10

15

01-Jun 01-Jul 31-Jul 30-Aug 29-Sep 29-Oct

Date

mg

/L

MD 2001

Dissolved oxygen upstream

Temperature oC

0

2

4

6

8

10

12

14

20 22 24 26

De

pth

m

18-Jul

Specific Conductance mS/cm

0

2

4

6

8

10

12

14

0 0.5 1

De

pth

m

Dissolved Oxygen mg/L

0

2

4

6

8

10

12

14

2 4 6 8 10 12 14

Dep

th m

Oxygen depletion was not caused by stratification

-0.80

-0.40

0.00

0.40

0.80

26-Jun 18-Jul 16-Aug 29-Aug 14-Sep 3-Oct

Date

ox

yg

en

de

ma

nd

mg

/L

net oxygen demand phytoplankton bacteria

Oxygen demand was not caused by phytoplankton respiration

2001

0

2

4

6

8

26-Jun 25-Jul 16-Aug 5-Sep 3-Oct

Date

mg

/L o

xyg

en

TBOD NBOD CBOD

Oxygen demand was caused by nitrification

Pearson Correlation Coefficients (n=103)

TBOD & NBOD 0.86

NBOD & ammonia 0.93

NBOD & organic N 0.34

TBOD & ammonia 0.78

TBOD & CBOD 0.62

TBOD & chlorophyll 0.59

Year n R2

2000 100 0.91

2001 85 0.73

2000 + 2001 185 0.83

Stepwise Regression

Dissolved ammonia + carbonaceous BOD 60%

30%

Where does the ammonia come

from ?

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 1 2 3 4 5 6

NBOD

Am

mo

nia

loa

d R

WC

F k

g/d

ay r = 0.74

NBOD was correlated with ammonia load from treatment plant

NBOD at Rough and Ready varied with the ammonia load from the treatment

plantRough and Ready

0

1

2

3

4

5

6

4-Jun 4-Jul 3-Aug 2-Sep 2-Oct

Date

NB

OD

10

mg

/L

0

1000

2000

3000

4000

5000

RW

CF

NH

4-N

(l

bs

/da

y)

RRRWCF

Total nitrogen load was higher from upstream

0

500

1000

1500

2000

2500

3000

Month

TK

N l

oad

k

g d

-1

June July August September October

Mossdale (MD) waste treatment plant

Mass Balance Model

Object: Determine the largest source of dissolved ammonia in the channel

Simple mass balance model

Daily dissolved ammonia load into the ship channel from the treatment plant and upstream

1) daily load of dissolved ammonia from each source

2) daily load of dissolved ammonia from the oxidation of the organic nitrogen load from each

source

3) daily load of dissolved ammonia from the oxidation of residual organic nitrogen from

previous day from each source

+

+

=

0

50

100

150

200

0 5 10 15 20 25 30

Day

chlo

rop

hyl

l a

ug

l -1

00.10.20.30.40.50.60.70.8

amm

on

ia m

g l

-1

chlorophyll aammonia Log. (ammonia )

Ammonification rate

010203040506070

1 5 10 15 20 25

Residence time days

Me

dia

n p

erc

en

t

Waste treatment plant Mossdale

Upper boundary condition:

all organic nitrogen oxidized at ammonification rate for chlorophyll (highest rate)

Chlorophyll was a small percent of the organic nitrogen load

05

1015202530354045

27-Jun 18-Jul 25-Jul 1-Aug 16-Aug 29-Aug 14-Sep 3-Oct

date

per

cen

tag

e

010203040506070

1 5 10 15 20 25

Residence time days

Me

dia

n p

erc

en

t

Waste treatment plant Mossdale

Lower boundary condition:

only the organic matter associated with live chlorophyll was oxidized

Summar

y• Oxygen demand in the channel was primarily caused by nitrification

• The treatment plant could be the primary cause of nitrification in the channel on a daily basis even though it had a small ammonia load because it was a direct source of dissolved ammonia for bacterial oxidation

• The relative contribution of ammonia from the treatment plant and upstream to ammonia in the channel was a function of residence time, ammonification rate, direct loads and load composition

Take home message

The oxygen demand produced from the direct load of dissolved ammonia from the treatment plant could have a greater impact on daily oxygen demand in the channel than the oxidation of organic nitrogen from upstream because of the slow oxidation rate and low reactivity of upstream organic matter

0

10

20

30

40

50

60

70

80

18-Jul 1-Aug 16-Aug

29-Aug

14-Sep

3-Oct

Date

ch

loro

ph

yll

ug

l -1

Mossdale

Channel Point

Net transport of phytoplankton mass decreased downstream

Net transport kg d -1

Percent retention

%

Net transport kg d -1

Percent retention

%

Net transport kg d -1

Percent retention

%

Net transport kg d -1

Percent retention

%

Week

3-Jun 49 91 903 50 -61 -17 7489 61

10-Jun 25 89 988 64 72 20 6287 69

1-Jul 8 19 -389 -37 8 1 -206 -1

12-Aug 8 27 -181 -11 418 32 -1166 -11

19-Aug 28 85 1054 77 787 69 8025 73

9-Sep 13 51 791 37 333 44 4166 37

16-Sep 41 77 1226 49 782 50 4638 34

7-Oct 32 47 1112 47 3056 84 10186 52

median 27 64 946 48 375 38 5462 44

10th percentile 8 19 -389 -37 -61 -17 -1166 -11

90th percentile 34 86 1068 54 783 55 7623 63

organic nitrogen ammoniachlorophyll a total BOD

Model residence

time MD

median 10th

percentile90th

percentileWTP

median 10th

percentile90th

percentileSignificant difference

sample size

day percent percent level n

Run 1

1 38 16 52 62 0 72 < 0.01 102

5 49 40 56 51 18 56 ns 20

10 55 42 57 45 29 49 < 0.02 10

15 61 45 61 39 35 46 < 0.04 7

20 58 50 62 42 33 46 < 0.04 5

25 58 56 59 42 38 43 ns 4

Run 2

1 34 6 47 66 0 83 < 0.01 102

5 38 15 47 62 35 70 < 0.01 20

10 43 26 45 57 46 69 < 0.01 10

15 42 31 46 58 46 64 < 0.02 7

20 38 35 45 62 48 63 < 0.05 5

25 41 34 44 59 49 61 ns 4