SEDIMENT OXYGEN DEMAND (SOD) STUDY
CALCASIEU RIVER ESTUARY
LAKE CHARLES, LOUISIANA
MAY 1984
ENVIRONMENTAL PROTECTION AGENCY
SURVEILLANCE AND ANALYSIS DIVISION
ATHENS, GEORGIA
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SEDIMENT OXYGEN DEMAND (SOD) STUDY
CALCASIEU RIVER ESTUARY
LAKE CHARLES, LOUISIANA
MAY 1984
Environmental Protection Agency
Environmental Services Division
Athens, Georgia 30613
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TABLE OF CONTENTS
Page
Project Personnel ii
Introduction 1
Study Area and Station Location 1
Methods 1
Results and Discussion 3
Figure 1 2
Table 1 5
Appendix A A-l
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PROJECT PERSONNEL
EPA EQ
Don Lawhorn, Engineering Technician Kurt Manuel
*Philip Murphy, Biologist Larry Racca
Duggin Sabins
Ron Smith
Kary St. Pe*
Will Tucker
* Author
ii
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SEDIMENT OXYGEN DEMAND STUDY
CALCASIEU RIVER
LAKE CHARLES, LOUISIANA
May 1984
Introduction
At the request of the Louisiana Department of Environmental
Quality (LDEQ) through EPA, Region VI, Dallas, personnel of the
EPA, Region IV, Environmental Services Division, Ecological Sup-
port Branch conducted a sediment oxygen demand (SOD) study on
the Calcasieu River at Lake Charles, Louisiana. The purpose of
the study was to determine sediment oxygen demand rates along
the Calcasieu River for input and calibration of a wasteload
allocation model being developed for the study area. With the
assistance of LDEQ personnel, sampling station selection was ac-
complished during a reconnaissance on April 18, 1984 with field
work accomplished during the period of May 7-14, 1984. A tabular
presentation of SOD data has already been furnished to LDEQ.
Study Area and Station Locations
The study area for SOD sampling was that portion of the Cal-
casieu River delimited upstream by Station 002 on the West Fork
Calcasieu River: and downstream to.fCalcasieu Lak'e and including
Bayou d'Inde.
A total of eight (8) stations were studied along this reach
with the numbering sequence corresponding to LDEQ station loca-
tions (Figure 1).
Methods
Determination of SOD rates was accomplished by diver, deploy-
ment of opaque acrylic chambers over bottom sediments and record-
ing the decay rate of oxygen inside the chambers over a time peri-
od. During the course of the experiment, water within the chamber
was circulated continuously at approximately 0.1 foot per second.
A detailed presentation of the methods employed are contained
in the Ecological Support Branch's, Standard Operation Procedures
manual, and accompany this report- (Appendix A) ».
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2
Figure JL'
Station Locations
Calcasieu River SOD Study
kjmtoon'
bridge ;
v "
) "
i "
\ ii
V
yn i
o '¦
C II J
«II I
21" I
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3
Result and Discussion
Within the study reach, SOD chambers were deployed over a
variety of habitats which included river run channel, dredged ship
channel, bayou, lake, and near shore submerged mud flats. Figure 2
presents a non-scaled schematic drawing of station locations
relative to the varying hydrologic and benthic character of the
study area.
River run sampling location were located above the saltwater
barrier and are represented by Stations 002 and 004. Although
substrate differences, based on diver observations, were evident
between the two stations, SOD rates were very similar with mean
rates of 0.0270 and 0.0265 g02/m /hr at Stations 002 and 004,
respectively (Table 1). Extended to a 24-hour (day) respiration
rate, each of these stations averaged 0.65 g02/m /day.
SOD experiments in the dredged ship channel are represented
by rates associated with Stations 025 and 008. Station 025 ex-
hibited a mean rate of 0.0272 g02/m /hr (Table 1) or 0.65 g02/m /
day, similar to the upstream river run stations. Although rate
determinations were conducted at Station 008, they are not in-
cluded in Table 1 due to the following qualifications'. At Station
008, initial dissolved oxygen concentrations at the water/sediment
interface were so suppressed (0.5 mg/L) that experiments had to be
terminated at considerably shorter incubation times than normal.
Accordingly, due to the initial DO concentrations near zero (0)
and the short observation time, rates obfcained^at this station may
be somewhat less reliable thaip those obta'ined'at all other sta-
tions. Since rates obtained under such circumstances are question-
able, SOD experiments conducted under such conditons are outside
EPA, Region IV, ESD standard operating procedure. For these
reasons, Station 008 rates are not included in Table 1. However,
for discussion purposed only, a"mean SOD rate of 0.0205 g02/m /hr
(based on four replicates) or 0.50 g02/m^/day was observed at
Station 008.
Lake station.SOD rates are represented by Station 007 in
Lake Charles and station 036 in Calcasieu Lake. Both stations were
characterized by open, shallow water (7 to 8 feet) and soft,- fine
substrate. A mean SOD rate of 0.0264 g02/m /hr was observed at
Station 007 in Lake Charles, which is consistent with the rates
reported above for river run and ship channel stations. Rates
in Calcasieu Lake were slightly greater than those in Lake Charles.
Station 036 in the northern section of Calcasieu. Lake exhibited a
mean SOD rate of 0.0348 g02/m2/hr (Table 1) or 0.84 g02/ni /day.
Bayou D' Inde receives large, volumes of heated industrial
discharge as well as domestic waste water. Additionally, much of
its shoreline and adjacent land consists of. brackish water marsh-
land.. Diver observation of the. Bayou D' Inde- substrate revealed
it_ to be a- finely divided, soft, substrate-underneathe a. more,
chunky, irregular, large fragment layer. The substrate, surface-
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-4-
probably reflects the input of wetland material and eroding banks
along the narrow channel. The water column of Bayou D' Inde was
heated but well oxygenated. Benthic respiration rates at Station
019 in Bayou D' Inde averaged 0.0550 gC^/mVhr (Table 1) or 1.32
gC>2'/ni2/day, nearly twice those reported in river run and ship
channels (Table 1). Based on previous studies throughout the
southeast, the increased water temperature was likely the prevail-
ing influence elevating SOD rates in Bayou D' Inde along with the
different substrate character.
Originally, SOD experiments were planned for the ship channel
at Station 015, Coon Island loop (Figure 2). On-site, however,
it was decided that SOD rates determine shoreward of the channel,
in the shallow flats, would be more representative of the Coon
Island loop area than the channel proper. Additionally, pending
ship movements made deployment in the channel uncertain. At this
location, diver observation revealed light penetration to the shallow
bottom to be adequate for the possible existence of a microscopic
plant community normally associated with marsh muds and adjacent
shallow water zones. The enhanced metabolic activity of this zone
was reflected in the highest mean SOD rate observed in the project
area, 0.0690 g 02/m /hr or 1.66 g >2/ /day. The higher SOD rate
exhibited by this shallow water, non-channel, wetland associated
zone should receive thorough consideration in defining the oxygen
1 budget of this portion of the Calcasieu River estuary. Since it
represents only one mean rate, based on five replicate observations,
expansion of the rate to othei: zones in the" study area should be
done with caution. However, sinpe much of ~the*'study area is pro-
bably represented by this type- of ' benthic community (sediment and
hydrographic mapping could determine the ratio of shallow water to
dredge channel area), and since in every case non-channel SOD rates
were greater than in-channel rates any modeling effort should be
cognizant of and take into account the rate increases associated
with shallow, wetland associated benthic communities versus deep
channel areas.
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Table . Sediment Oxygen Demand (SOD) Rates (Replicates and Means),
Calcasieu River, Lake Charles, Louisiana, May 1984.
Station
Rep
Avg. Rate of
Change
(mg/L/min)
Adjusted Avg.l
mg/L/min
Respiration (R)
or SOD
g 02/m^/hr
Mean R
or SOD
g 02/m2/hr
2
A
C3
Water Column
Respiration
(mg/L/min
/ ~
Water
Temp
(°C)
002
1
.00205
.00205
.029
.0270
.0054
20.1
-0-
24.0
2
.00218
.00218
.031
4
.00136
.00136
.019
5
.00204
.00204
.029
004
2
.00158
.00158
.023
.0265
.0087
32.8
-0-
24.0
3
.00270
.00270
.039
4
.00178
.00178
.025
5
.00132
.00132
.019
007
1
.00313
.00186
.027
>0264
.0058
22.0
.00127
24.2
(Lake
2
.00313
.00186
.027
Charles)
3
.00294
.00167
.024
4
.00259
.00132
.019
5
.00369
.00242
.035
015
1
.00452
.00429
.061
.0690
.0096
13.9
.00023
24.2
2
.00464
.00441
.063
3
.00601
.00578
.083
4
.00464
.00441
.063
5
.00547
.00524
.075
^Adjusted avg. obtained by subtraction of water column R from avg. rate of change (SOD) at mg/L/min level.
v= standard deviation
3C = coefficient of variation as percent
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Table (continued)
Station
Rep
Avg. Rate of
Change
(mg/L/min)
Adjusted Avg.^
mg/L/min
Respiration (R) .
or SOD
g O^/n^/hr
Mean R
or SOD
g 02/m2/hr
2
C3
t- i
Water Column
Respiration
(mg/L/min)
Water
temp.
(°C)
019
1
.00600
.00420
.060
.0550
.0150
27.3
.00180
26.0
(Bayou
2
.00447
.00267
.038
d'Inde)
3
.00690
.00510
.073
5
.00523
.00343
.049
025
1
.00178
.00178
.025
.0272
.0061
22.3
-0-
24.5
2
.00170
.00170
.024
3
.00262
.00262
.038
4
.00175
.00175
.025
5
.00166
.00166
.024
036
1
.00333
.00238
.034
.0348
.0051
14.6
.00095
23.0
(Calcasieu
2
.00333
.00238
.034
Lake)
3
.00333
.00238
.034
4
.00392
.00297
.043
5
.00295
.00200
.029
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002
004-
a/1
OH 007^^
', denotes c/t-eJcfed
14^ sAtp channel
UJeST fob I. C&lcOSIEtL
/Live* mn chnnr>£L
Ca.(caete.u Z. flaove sol/4 bfihUeh
/Zivah bun chnnneL.
Lale CJlRtfcS
fake station
Calcasieu &. /mmediadely nbctie port
_^£htp gJw/wel. s+aJjon
Coon Xs/and Loop
Mud Plat between ship chaNNEL
RNd left bnntLCmfthsk)
3/)you 2 ' Tnde
aavou station -mid sft-eaun
daJc/LS/eu Ship cJmnnel.
Le.fi £/de.-wtrhtn cJiftnntu
Calcasieu L/lkl.
Abj-lh end- rrud fakl station
Figure 2. Schematic of Station
Locations With Reference to Channel
and Non-channel Sampling, Calcasieu
River, May 1984.
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APPENDIX A
A-l
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Section No. 2.12
Revision No. 1
Date: June 1984
Page 45 of 53
o SOD Chamber
o Photometer
o Pyranograph
o Dissolved oxygen meters and Winkler chemicals
o Sali.nometer
o Conductivity meter
o Thermistor
o KC1 solution
o BOD bottles
o Corer
o Collection bags for vegetation
A
2.12.9.2" Procedures
' 5# *
o Investigators should calibrate dissolved oxygen meters
(Winkler method) and other monitoring equipment such as
salinometers, conductivity jneters, and recorders; DO
probe should be self-stiir>ririg.
o Then team should begin recording daily' solar intensity if
benthic. primary production rates are desired and obtain
vertical profile of dissolved oxygen, light extinction,
and other desired parameters such as temperature, salinity
and conductivity; continue procedures by checking delivery
of power and operation of circulation pump.
o After preliminary checks and information gathering are
completed, team should deploy chamber with lid open gently
lowering the chamber with rope. When chamber is on the
bottom, placement, positioning, and securing of seal and
lid closure should be done by"divers. The chamber used
for monitoring water column respiration (called a "blank"
since it is isolated from the sediment by a glass bottom)
should be deployed first and purged with bottom water for
at. least 15 minutes prior to sealing. Other chambers can
be deployed while this process occurs. Be- sure that.purge
valve is closed after purging.
2.12-45
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Section No. 2.12
Revision No. 1
Date: June 1984
Page 46 of 53
Approximately 15 minutes should be allowed for settlement
of any resuspended materials; then team should start pump
and place monitoring probes in chamber. Ambient probes
should be lowered to dome level and approximately one foot
above bottom; record initial monitoring data. (Note: If
used in fresh water, salt solution can be injected into
pump discharge port at this time if desired).
In conjunction with use of the "blank" chamber to assess
respiration of the water column, bottle (dark) experiments
are advised as back-up source of data since only one "blank"
chamber is used. The dark bottle experiments should begin
at this time positioned at same depth as chamber. A minimum
of two bottles should be filled with bottom water collected
adjacent "to chambers and deployed alongside the chambers for
incubation during the course of the SOD experiments.
Team should record monitoring data either continuously or
at 15-minute intervals. If 15-minute intervals are used,
pjobe stirrer may be turned off between readings' but should
Be turneti on a sufficient time (approximately 1 minute) be-
fore reading so meter can reach stabilization; check zero
and power output (red line) of DO meter frequently; con-
tinue experiment for approximately 1 hour.. Oxygen readings
at 15-minute intervals during the period-iyrill provide suf-
ficient data points for 4naiysis.
After obtaining a sufficient number of data points, monitor-
ing probes should be removed from dome and calibration checked *
Immediately after the experiment, team should collect sediment
core and vegetation biomass from within dome placement if so
desired.
Of the five'replicates attempted, a minimum of three should
be determined successful, on-site, or else the experiments
repeated.
Sealing of chamber to substrate should be conducted and con-
firmed by divers in both salt and fresh water. Additionally,
in fresh waters a concentrated salt, solution may be injected
into the chamber and conductivity monitored. Any decline in
conductivity after equilibrium would indicate intrusion of
outside ambient water.
Pump operation should be determined, prior to chamber, deploy-
ment" and confirmed by divers prior to- securing- the vlid to
the- chamber .
2.12-46
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Section No. 2.12
Revision No. 1
Date: June 1984
Page 47 of 53
Resuspension should be visually checked by divers in
waters with sufficient clarity, but in all cases a 10-
minute time delay is observed prior to beginning pump
operation to allow time for settlement. Plotting of
observed data points during and after experiments also
should be accomplished to determine resuspension and its
effect on SOD rates.
Between and post experiment calibration checks should be"
accomplished by removing DO probes from chambers during
relocation or retrieval and positioning the chamber probes
adjacent to the ambient probe. Similarity in probe measured
DO concentrations (less than 0.5 mg/L deviation) indicates
adequate calibration maintenance. Deviation in concentra-
tions beyond the above dictates recalibration via Winkler
method.
All light and dark bottle DO concentrations should be deter-
mined generally according to Standard Methods (1980).
2.12.9.3<-* SOD Rate Calculations and Data Assessment
During in-situ SOD rate determinations, the decay or production
rate of oxygen is recorded as the instantaneous dissolved oxygen con-
centration at specific time intervals, usually 10 .or 15 minutes. The
specified interval must be adhered,./to throughout''each individual ex
periment.
Rate calculations are accomplished by solving the equation:
6 . = 9 °2/m /hr
where,
3 = rate of change in DO as mg 02/L/min
v = chamber volume in liters
A = chamber area in meters square
.06 = constant
Beta (g) is determined by calculation- of the average rate of
change in DO (mg 02/L/minute) for each recorded interval. Nega-
tive rates represent: respiration (R) of- the benthlc community
while positive rates-, obtained, only in the- clear chamber, Repre-
sent net primary production (NPP).
2.12-47
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Section No. 2.12
Revision No. 1
Date: June 1984
Page 48 of 53
All rates should be adjusted for water column metabolic
functions -at the mg 02/L/min level before being extended to
the hourly rate. Light and dark, bottle (water column NPP and
R) values should be determined by simple division of the average
change in DO concentration within each set of bottles by the
incubation period.
2.12.9.4 Precision (see section 2.11.2)
2.12.9.5 Quality Control Checks with Acceptable Limits When/Where
Applicable
All DO meters should be calibrated via the Winkler method
(Standard Methods;/ 1980) prior to determination of dis-
solved oxygen profile and initiation of SOD experiment.
Salinometer and conductivity meters should be calibrated
electronically.
Sealing of chamber to substrate should be conducted and
confirmed by divers in both salt and fresh water. Ad-
'ditionally, in fresh waters a concentrated salt solution
may be injected into the chamber and conductivity monitored.
Any decline in conductivity after equilibrium would indi-
cate intrusion of outside"'ambient wa.tar..
; t
I
Pump operation should be-determined prior to chamber de-
ployment and confirmed by di-vers prior to securing the
lid to the chamber.
Resuspension should be visually checked by divers in waters
with sufficient clarity, but in all cases a 10-minute time
delay is observed prior to beginning pump operation to allow
time for settlement. Plotting of observed data points dur-
innng' and after experiments also should be accomplished._.to
determine resuspension and its effect on SOD rates.
Between and post experiment calibration checks should be
accomplished by removing DO probes from chambers during re-
location or retrieval, and positioning the chamber probes
adjacent to the ambient probe. Similarity in probe measured
DO concentrations (less than 0.5 mg/L. deviation) indicates
adequate calibration maintenance.. Deviation in concentra-
tions beyond the above dictates recalibration.
All light and dark- bottle. DO concentrations should be deter-
mined via Standard Methods (1980).
2.12-48
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