United State?
Environmental Pictecrtun
Agency
trutuMrml Environmental
lnangle Park NC
EPA 600/7 78-221
November 1978
Assessment of the Effects
of Chlorinated Seawater
from Power Plants on
Aquatic Organisms
<*
Interagency
Energy/Environment
R&D Program Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development. US Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields
The nine series are
1 Environmental Health Effects Research
2 Environmental Protection Technology
3 Ecological Research
4 Environmental Monitoring
5 Socioeconomic Environmental Studies
6 Scientific and Technical Assessment Reports (STAR)
7 Interagency Energy-Environment Research and Development
8 "Special Reports
9 Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series Reports m this series result from the
effort funded under the 17-agency Federal Energy Environment Research and
Development Program These studies relate to EPA s mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems The goal of the Program is to assure the rapid development of domestic
energy supplies m an environmentally-compatible manner by providing the nec-
essary environmental data and control technology Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects, assessments of. and development of. control technologies for energy
systems, and integrated assessments of a wide'range of energy-related environ-
mental issues
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
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commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service Spnngfielo. Virginia 22161
-------
NOTICE
THIS DOCUMENT HAS BEEN REPRODUCED
FROM THE BEST COPY FURNISHED US BY
THE SPONSORING AGENCY. ALTHOUGH IT
IS RECOGNIZED THAT CERTAIN PORTIONS
ARE ILLEGIBLE, IT IS BEING RELEASED
IN THE INTEREST OF MAKING AVAILABLE
AS MUCH INFORMATION AS POSSIBLE.
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TECHNICAL REPORT DATA
(Please read ItiUructions on the reverse before completing)
1 REPORT NO.
EPA-600/7-78-221
3. REC
:'\s
4 TITUEANOSUBT'TLE Assessment of the Effects of
Chlorinated Seawater from Power Plants on Aquatic
Organisms
6 REPORT DATE
November 1978
6 PERFORMING ORGANIZATION CODE
7 AUTHOHIS)
R.Sung, D, Strehler, and C, Thome
8. PERFORMING ORGANIZATION REPORT NO
B PERFORMING ORGANIZATION NAME AND ADDRESS
TRW, Inc,
Environmental Engineering Division
Redondo Beach, California 90278
10 PROGRAM ELEMENT NO,
EHE624A
11. CONTRACT/GRANT NO.
68-02-2613, Task 13
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final; 5-9/78
14. SPONSORING AGENCY CODE
EPA/600/13
IB.SUPPLEMENTARY NOTES TjERL-RTP project officer is Michael C. Osborne, MD-61, 919/
541-2898
i6 ABSTRACT Tne report gives a detailed review of past and present research efforts on
the effects of chlorinated seawater .fjrom power plants on aquatic organisms. It inclu-
des: (1) a characterization of chemical species contained in power plant seawater
discharges; (2) a review of the amperometric titration method for residual chlorine
determinations in seawater: and (3) an analysis of the toxicity of compounds formed
by chlorination of seawater. The review concluded that (1) the toxicity of chlorinated
seawater effluent is due primarily to various oxidant residuals produced by chlori-
nation, rather than to residual chlorine itself; (2) the amperometric titration method
is adequate to determine safe oxidant levels when identification of specific com-
pounds is not required; (3) bromoform is a principal contributor to toxicity in power
plant discharges (because of volatility and degradability, bromoform is not expected
to be as toxic as chloroform); and (4) other compounds suspected of causing toxicity
have not been clearly identified. Further studies into the actual components present
in chlorinated power plant seawater discharges are necessary to determine exactly
which compounds are responsible for the toxicological effects.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Pollution Toxicity
Sea Water Oxidizers
Chlorination Bromoform
Electric Power Plants
Aquatic Animals
Electrical Measurement
18. DISTRIBUTION STATEMENT
Unlimited
b IDENTIFIERS/OPEN ENDED TERMS
Pollution Control
Stationary Sources
Amperometric Titration
c. COSATi Field/Group
06T~
11G .
19. SECURITY CLASS (TMs Rtpon)
Unclassified
20 SECURITY CLASS (Thispage/
Unclassified
13B
08J
07C,07B
10B
08A,06C
14B
21 NC
22 PRICE
EPA Form >»ZO-t
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EPA-600/7-78-221
November 1978
Assessment of the Effects of
Chlorinated Seawater from Power
Plants on Aquatic Organisms
by
R Sung D Strehlwr, and C Thome
TRW Inc
Environmental Engineering Division
Heclonrio Beach California 90278
Contract No 68-02 2613
Task No 13
Proqnm Element No EHE624A
EPA Project Olhcei Michael C Osbome
Industrial Environmental Research Laboratory
Office of Energy Minerals and Industry
Research Triangle Park NC 27711
Prepared for
U S ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington DC 20460
-------
EXECUTIVE SUMMARY
This report was prepared for the U.S. Environmental Protection Agency
to provide a comprehensive review of available data on the effects of chlor-
inated seawater from power plants on aquatic organisms. The report is a com-
pilation of published and unpublished research efforts, and communication with
individuals currently involved in related studies. Three areas were investi-
gated: 1) chemical characterization of power plant discharges produced by chlor-
inating seawater, 2) the toxicity of the compounds,identified in (1), to aquatic
organisms, and 3) methods for determining the presence of chlorine and/or chlor-
ine derived oxidants in seawater.
The culmination of this effort produced the following overall con-
clusions and recommendations:
The toxicity of chlorinated seawater effluent from power plant cool-
ing systems is due primarily to the presence of various oxidant re-
siduals produced by chlorination rather than to just residual chlor-
ine.
t The amperometric titration method is generally adequate to measure
total oxidant residuals, (which include chlorine and bromine residuals)
where identification of specific compounds is not required.
Further studies are required to determine both individual species
present in chlorinated power plant discharges and the toxicity of
the identified species on aquatic organisms.
More specific analytical procedures may be required if it is found
that individual compounds are significantly more toxic at lower
levels than can be measured presently.
It should be noted that each power plant presents a unique situation.
Site specific parameters (such as compound in the intake water, etc.) as
well as the types of aquatic life which exists in the discharge area must be
considered for both analytical measurements and toxicity studies.
11
-------
CONTENTS
Executive Summary ii
Figures iv
Tables v
1. Introduction 1-1
2. Conclusions and Recommendations 2-1
Conclusions 2-1
Recommendations 2-2
3- Characterization of Chlorinated Seawater from Power
Plants 3-1
Cooling System Description 3-1
Characterization of Raw Seawater 3-3
Characterization of Chlorinated Seawater 3-11
Comparison of Identified Chlorinated Seawater Species
to the List of 129 Toxic Pollutants 3-21
4. Evaluation of Amperometric Titration for Determination
of Residual Chlorine in Seawater 4-1
General Method Description 4-1
Iodine Chemistry 4-3
Limitations and Interferences 4-5
Interferences Particularly Related to Seawater 4-7
5. Toxicity of Compounds Formed by Chlorination of Seawater. . 5-1
Definition of Toxicity 5-1
Identification of Potentially Toxic Species 5-5
Identification of Toxic Levels and Aquatic Organisms
Affected 5-7
Comparison of Toxic Levels with Levels Expected from
Power Plant Discharges 5-18
Qualitative Analysis of the Toxicity and Measurment of
Pollutants Formed in Chlorinated Seawater . 5-20
References 6-1
Bibliography 7-1
-------
FIGURES
Number Page
] Approximate amount of seawater required by a once-through
cooling system for steam electric power plants 3-2
2 Schematic Flow diagram of power plant 3-4
3 Flow diagram of a typical once-through cooling system using
seawater 3-5
4 Principle species of bromine and bromamine 3-17
5 Degradation processes for chlorine in saline waters 3-18
6 Chlorine substitution reaction 3-20
7 Toxicity of chlorine to marine organisms 5-23
IV
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TABLES
Number Page
1 Typical Design Free C10 and C^ Residue Concentrations, . . 3-6
2 Concentration of Major Ions in Seawater
(g/Kg Seawater) Normalized to 35%0 Salinity 3-8
3 Chemical Species in Seawater 3-9,3-10
4 The Major Chemical Species in Seawater 3-12
5 Minor Constituents of Seawater 3-13
6 Dissolved Organic Compounds in Seawater 3-14
7 Potential Interferring Oxidants 4-4
8 General Categories of Toxic Effects 5-2
9 Techniques Generally Used for Conducting Toxicity Tests . . 5-3
10 Terminology Used for Expressing Results of Toxicity Tests . 5-4,5-5
11 A Preliminary List of the Chemical Constituents Identified
in Chlorinated Seawater 5-6
12 Summary of Data on Toxicity of Chlorine to Marine Organisms 5-8 - 5-12
13 Summary of Toxicity of Various Chemical Species to Marine
Organisms 5-13-5-16
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SECTION 1.0
INTRODUCTION
Large volumes of cooling water are required by power plants. Often this
requirement is met by locating the power plant near a major body of water.
Because of the favorable conditions for aquatic organism growth within the
cooling water system, most power plants are confronted with biofouling pro-
blems. Bacterial and algoid slimes, and higher order aquatic organisms often
attach themselves to surfaces within the cooling circuit, thus reducing cool-
Ing system flow rates and heat transfer efficiencies. The use of chlorine
has been the most»'common method for controlling biofouling.
Chlorine when used in this and other applications, may present toxico-
logical problems to aquatic organisms in the receiving waters. The toxicity
of chlorine and chlorination derived oxidants from power plant cooling water
discharges are presently being investigated by the various researchers. The
impetus for these investigations are: 1) PL 92-500 Section 307(a) of the toxic
substances control act, which requires that each pollutant be individually
studied, assessed and regulated and a settlement between EPA; and 2) the
environmental groups relating to toxic material discharges.
This report was prepared under the direction of the EPA to provide a
portion of the base from which regulations may be promulgated. The main ob-
jectives of this study are the characterization of seawater, evaluation of
amperometric titration for determining residual chlorine in seawater, and
the assessment of toxicity from seawater chlorination. To meet these ob-
jectives, this report includes a state-of-the-art review of available data
from past studies on the aforementioned topics. In addition, current on-
going research studies investigating various aspects of the characterization
of chlorinated seawater, toxicity or measurement techniques were either iden-
tified or contacted.
1-1
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SECTION 2.0
I
CONCLUSIONS AND RECOMMENDATIONS
During the course of this study it has become evident that additional
chlorinated seawater research should be initiated. This section will high-
light the conclusions which were reached in each of the subject areas (chlor-
inated seawater characterization, amperometric titration and toxicity) and pre-
sent recommendations for further research.
Conclusions
Characterization of Chlorinated Seawater
The chemical compounds present in seawater power plant discharges
are dependent upon several factors: 1) chemical species present in
intake water, 2) chlorine dosage, 3) reaction duration, 4) pH, 5)
temperature, and 6) light exposure-
A complete chemical analyses of individual species present in chlor-
inated seawater have not been performed. The requirement for site
specific information calls for each power plant discharge to be an-
alyzed separately to eliminate potential sources of extraneous in-
fluence.
Many of the compounds suspected or identified to be present in
chlorinated seawater are either contained in the list of 129 toxic
substances, or are potentially toxic although not presently included
in this list.
Amperometric Titration
« The amperometric titration method is presently considered the best
available method for analyzing oxidants in all water types by a
majority of researchers. This method can determine chlorine resi-
duals quantitatively, however, only in fresh water.
Many compounds in chlorinated seawater interfere with the ampero-
metric titrations in the measurement of free and/or combined chlor-
ine residuals.
2-1
-------
Current technology indicates that the amperometric titration method
can measure reliably concentration of residual oxidant up to a de-
tection limit of 0.01 mg/1, which is half the toxicological limit
identified by Mattice as causing chronic toxicity to marine organ-
isms in power plant discharge,
Toxicity of Chlorinated Seawater
0 Chlorination of seawater has been shown to cause toxic reactions in
various aquatic life forms. The specific compounds causing the toxic
effects, however, have not been quantified.
Bromoform, a by-product of seawater chlorination, has been identi-
fied as a major contributor to toxicity in power plant discharges.
However, preliminary assessment by various researchers indicated
that bromoform may not be as toxic as chloroform because of its
volatility and degradability in seawater. Further study is necessary
to substantiate this claim.
Other brominated compounds suspected to cause toxicity have not been
clearly identified due to lack of specific analytical techniques.
Recommendations
Continue research into characterization of chlorinated seawater.
Based upon specific chemical species identified in the characteri-
zation studies, begin toxicological studies, using continuous flow-
through system.
Develop more sophisticated analytical techniques such as GC/MS which
will measure quantitatively those compounds identified as toxic to
aquatic organisms.
Revise terminology used in chlorinated seawater measurements; rather
than specifying free or residual chlorine measurements the appropri-
ate terminology should be total oxidant or chlorine derived oxidants
measurements instead.
Compile and evaluate toxicity data of other biocides other than
chlorine for condenser tube biofouling control.
Conduct bench scale studies to evaluate control technologies for the
removal of organics that react with chlorine to cause toxicity.
2-2
-------
Evaluate alternative analytical methods for chlorine residual measure-
ment, if research indicates that chlorine residuals specifically ac-
count for the toxicity of the power plant discharge.
Evaluate the effects of dechlorination (using sulfur dioxide or sodium
sulfite) on potential toxicity reduction.
2-3
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SECTION 3.0
CHARACTERIZATION OF CHLORINATED SEAWATER FROM POWER PLANTS
An important consideration in the assessment of the amperometric titra-
tion method as well as the evaluation of toxicity of chlorinated seawater is
the understanding of the nature and characteristics of chlorinated seawater
from power plants. To this end, the section is divided into: (1) power
plant cooling system description; (2) characterization of raw seawater; (3)
characterization of chlorinated seawater; and (4) comparison of identified
chlorinated seawater species to the list of 129 toxic pollutants. The fol-
lowing is a detailed discussion on these areas.
Cooling System Description
Most power plants, whether fossil fuel or nuclear, require large amounts
of water to dissipate waste heat. The source of the water used is generally
nearby natural water bodies; therefore, coastal power plants usually use
seawater for cooling.
The typical power plant cooling circuit is a once-through system de-
signed for an 11°C (20°F) temperature rise across the condenser coils. This
requires a water retention time of approximately 5 to 10 minutes within the
cooling circuit.
The amount of water required by a once-through cooling system is depen-
dent mainly upon the facility size in terms of gross generating capacity.
Figure 1 is a graphic presentation of the approximate amount of seawate'r re-
quired by a once-through cooling system for power plants of various gross gen-
erating capacities. It was developed by linearizing, using the least square
method, design flow rate data for several coastal power plants of dif-
ferent design gross generating capacities as reported by Hergot et.al. (1)
and Yu et al. (2)
The inherent drawbacks of cooling systems using water from natural
sources are the formation and growth of various biological species on
channel walls and condenser tubes. In extreme instances this growth can
cause plugging of the condenser tubes and reduces flow in the intake and
3-1
-------
2400
2000
o
I 1600
2
1200«
E
CD
800.
400-
0
0.
10
20
30
40
50
ar
Cooling water f!ow,r3te (m /sec)
200
400
600
800
Cooling Water Flow Rate (10J GPM)
Figure 1. Approximate amount of seawater required by a
once-through cooling system for steam electric
power plants.
1000
3-2
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SECTION 3.0
CHARACTERIZATION OF CHLORINATED SEAWATER FROM POWER PLANTS
An important consideration in the assessment of the amperometric titra-
tion method as well as the evaluation of toxicity of chlorinated seawater is
the understanding of the nature and characteristics of chlorinated seawater
from power plants. To this end, the section is divided into: (1) power ,
plant cooling system description; (2) characterization of raw seawater; (3)
characterization of chlorinated seawater; and (4) comparison of identified
chlorinated seawater species to the list of 129 toxic pollutants. The fol-
lowing is a detailed discussion on these areas.
Cooling System Description
Most power plants, whether fossil fuel or nuclear, require large amounts
of water to dissipate waste heat. The source of the water used is generally
nearby natural water bodies; therefore, coastal power plants usually use
seawater for cooling.
The typical power plant cooling circuit is a once-through system de-
signed for an 11°C (20°F) temperature rise across the condenser coils. This
requires a water retention time of approximately 5 to 10 minutes within the
cooling circuit.
The amount of water required by a once-through cooling system is depen-
dent mainly upon the facility size in terms of gross generating capacity.
Figure 1 is a graphic presentation of the approximate amount of seawater re-
quired by a once-through cooling system for power plants of various gross gen-
erating capacities. It was developed by linearizing, using the least square
method, design flow rate data for several coastal power plants of dif-
ferent design gross generating capacities as reported by Hergot et,al. (1)
and Yu et al. (2)
The inherent drawbacks of cooling systems using water from natural
sources are the formation and growth of various biological species on
channel walls and condenser tubes. In extreme instances this growth can
cause plugging of the condenser tubes and reduces flow in the intake and
3-1
-------
2400
2000'
0
I 1600
01
-------
discharge channels. Conditions such as these require unit shutdown and
drainage, and the chemical and/or manual removal of the fouling organism.
In less severe cases biological growth in the form of slime develops on
the condenser tubes, causing a degradation of the heat transfer character-
istics of the condensing unit which reduces the overall generating capacity
of the facility.
To counteract these problems, various methods have been used in an at-
tempt to control and/or curtail biofouling problems. The most successful
and widely applied method of biofouVing control is chlorination. The first
documentation of the successful application of chlorination in a commercial
power plant was in 1924, and the development of high-capacity chlorination
equipment commenced in 1930. Since that time chlorination for biofouling
control in power plants has enjoyed widespread use.
The basic power plant consists of a boiler, turbine/generator and cool-
ing system. A simplified diagram of this basic system is shown in Figure 2.
Basically the steam/condensate loop is a closed system, and the cooling water
circuit is an open loop. A simplified diagram of a typical once-through
cooling system is given in Figure 3. Water from a natural water body is
brought into the circuit through an intake channel; it is divided into par-
allel streams and then chlorinated. The chlorinated water passes through a
bar rack system in order to remove large debris, such as seaweed, kelp and
larger marine animals; it is pumped through the condenser and acts as a heat
sink as it passes through the condensers (typical design calls for an 11°C
(20°F) temperature rise. From the condenser it once again combines into a
single stream and passes through a common discharge channel back to the natu-
ral water body. Table 1 gives a summary of design chlorine concentrations
at the points identified as chlorine application and chlorine residue in
Figure 3. The Environmental Protection Agency has established guidelines
for the discharge of free chlorine to receiving water bodies; these guide-
lines allow 0.5 mg/1 maximum and 0.2 mg/1 average concentration for up to
two hours per day from any one unit (3). Many state standards are more
stringent than the federal standards.
Characterization of Raw Seawater
There are two basic terms used to describe seawater. The terms are
salinity and chlorinity. By definition, salinity is the content of dissolv-
ed salts 1n seawater; and chlorinity is the content of halogen ions other
, than fluoride in seawater. A great deal of information about the chemical
-------
STEAM
to
I
BOILER
CONDENSATE
REF. 2
OCEAN
Figure 2. Schematic flow diagram of power plant
-------
CO
I
en
POINTS OF CHLORINE
RESIDUE
DISCHARGE
(SEA)
CHLORINE APPLICATION
POINTS
- \
1
\
2
3
4
CONDENSERS
/* ~>
C^
* f ~\
(j
PUM
/"*
G
07
e
BAR
RACKS
INTAKE
(SEA)
Figure 3. Flow diagram of a.typical once-through cooling system using seawater
-------
TABLE 1. TYPICAL DESIGN FREE C12 AND C12 RESIDUE CONCENTRATIONS
Type of C12 Concentration at Clp Residue Concentration
Chlorlnatlon Point of Application Downstream of Condenser
Continuous 0.50 ppm free C12* 0.25-0.5 ppm*
Intermittent 1.5 - 4.0 ppm free C12 1.0 ppm
* Inlet water temperature greater than 277°K (40°F)
-------
nature of a given water sample is conveyed by the numeric values of these
terms.
The salinity of seawater varies only slightly in the major oceanic
water masses throughout the world. The extreme in salinity values as iden-
tified by Todd (4) range from a low of 33.5%0 for Subartic water in the North
Pacific to a high of 36.4%0 for Mediterranean water in the North Atlantic.
Smith (5) presented data which indicates that the mean value of salinity
for seawater is 35%0- This value will be used to normalize information
which will be presented in Tables 2 through 6.
Strickland (6) discussed the Knudsen equation which establishes a re-
lationship between chlorinity and salinity. The equation is as follows:
Sa = 0.030 + 1.8050 Cl
where:
Sa is salinity
Cl is chlorinity
By this relationship, assuming that the salinity of typical seawater
is approximately 35.0%0 then the chlorinity of typical seawater is approxi-
mately 19.4%0.
Tables 2 through 6, which are modified versions of data presented by
Smith (5), give an overall characterization of the most probable components
of seawater. Table 2 gives a list of eleven species which are the major ions
found in seawater as well as their respective concentration ranges. The data
presented is normalized to a salinity of 35%0 which corresponds (as per
Knudsen equation) to a chlorinity of 19.4%». As can be seen in the table the
average value of chloride is 19.353 g/kg which corresponds to approximately
19.4%0. The data presented in this table reveals that approximately 86% of
the total dissolved solids in typical seawater are sodium and chloride ions,
and that approximately 98% of the total dissolved solids are made of four
major ions (sodium, chloride, magnesium, and sulfate).
Table 3 presents a list of the chemical species found in seawater It
lists Individual elements and then the most connion chemical form in which
they are found in seawater. This table shows that certain elements, such
as carbon nitrogen and magnesium, are found in several forms; whereas,
others, such as chlorine and bromine are typically found in only one form.
3-7
-------
TABLE 2. CONCENTRATION OF MAJOR IONS IN SEA WATER (g/Kg SEA WATER)
NORMALIZED TO 35% SALINITY
Ion
Chloride
Sodium
Magnesium
Sulfate
Calcium
Potassium
Bicarbonate*
Bromide
Boron
Strontium
Fluoride
Ave. Value
19.353
10.76
1.297
2.712
0.4123
0.399
0.145
0.0673
0.0046
0.0078
0,0013
Range
-
10.72 -
1.292 -
2.701 -
0-4088
0.393 -
0.137 -
0.0666
0.0043
0.0074
0.0012
10.8
1.301
2.724 :
- 0.4165
0.405
0.153
- 0.0680
- 0.0051
- 0.0079
- 0.0017
* The values reported for bicarbonates are actually titrated alkalinities.
(Reference 5, page 4)
3-8
-------
TABLE 3. CHEMICAL SPECIES IN SEA WATER
Element
Hydrogen
He! i urn
Lithium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon
Sodium
Magnesium
Aluminum
Silicon
Phosphorus
Sulfur
Chlorine
Argon
Potassium
Calcium
Titanium
Vandium
Chromium
Manganese
Iron
Cobalt
Chemical Form
H20
He(g)
LI+
B(OH)3, B(OH)4
HC03> C03", C02, MgHC03, NaHC03°, MgC03°, organic compounds
NCC, N0~, NH0, N?(g), organic compounds
J f- J ? t-
HoO, 02(g), S04 , organic compounds
F", MgF+, CaF"1"
Ne(g)
Na+, NaS04, NaHC03°
Mg2"1", MgS04°, MgHCOj, MgC03°
A1(OH)3
Si(OH)4, SiO(OH)3
H2P04, HPO2-, POJJ-
SOj", NaS04, MgS04°, CaS04°
cr
Ar(g)
K+, KS04
Ca2", CaS04°, CaHC03
Ti(OH)4
V02(OH)2"
Cr(OH)2, CrOH2"1", Cr02, Cr04T HCr04, H2Cr04
Mn2+, MnS04°, Mn(OH)3 4
Fe(OH)3, Fe(OH)2
C°2+» CoS04° (Continued)
3-9
-------
TABLE 3. (Continued)
Element
Nickel
Copper
Z1nc
Germanium
Arsenic
Selenium
Bromine
Krypton
Rubidium
Strontium
Molybdenum
Silver
Cadmium
Iodine
Zenon
Cesium
Barium
Lanthanum
Tungsten
Gold
Mercury
Thallium
Lead
Radon
Radium
Chemical Form
Ni2*, NiS04°
Cu , CuS04°, CuOH*
Zn2+, ZnS04°, ZnOH+ .
Ge(OH)4°, GeO(OH)3
H3AsO~, H2As04, HAsO^", AsO^"
?
SeOj
Br"
Kr(g)
Rb+
Sr2+, SrS04°
o
MOO;
?-
AgClo, AgCr ,
CdCl , Cd2+, CdS04 °
10', I"
Xe(g)
Cs+
Ba2+, BaS04°
La3+, La(OH)2+
9_
woj
Ulttlultil
fiUw i A j nuv* i f\
7-
HgCK, HgCU
_ j tt
Tl4
Pb2+, PbS04°, PbOH+
Rn(g)
Ra2"*", RaSO.0
Uranium
U02(CO-
3-10
-------
Table 4 gives a list of major chemical species found in seawater, and
the probability of their occurrence given their elemental composition. This
table in conjunction with Table 2 can be used to determine the mass of a giv-
en chmical species per unit mass of seawater, e.g., there would be approxi-
mately 0.64 g of MgSO* in each kilogram of seawater. In Table 5 a list of
minor constituents found in seawater and their respective concentration
ranges, as well as, average concentrations are presented. These constitu-
ents are listed in the elemental form, and it is expected that all of these
together will make up less than 1% of the total dissolved solids in seawater.
Table 6 provides a list of dissolved organic substances found in sea-
water and their expected concentration ranges. Because of the large number
of organic compounds that are present in seawater, rather than identifying
each compound, it was decided, for the sake of brevity, to list only major
classes of organic species and the cumulative concentration of each class.
In his discussion of the character of seawater, Liptak (7) noted that
there is a difference between open ocean and coastal seawaters. In the open
ocean intense density stratification exists which hampers mixing between sur-
face and deep waters. Because of this the cycling of nutrients is hindered
(thus reducing biological activity). Whereas, in coastal waters, because
of shallow bottoms and constant tidal and wave activity, a great deal of
mixing occurs, which stimulates the cycling of nutrients. It is this cycl-
ing of nutrients and an abundance of suspended materials which provide an
environment conducive to active biological formation and growth. The pre-
sence of abundant aquatic life forms plus the conditions common to power
plant cooling systems, such as increased ambient temperatures and large sur-
face areas available for organism attachment, create an environment which
stimulates the occurrence of biofouling problems.
Characterization of Chlorinated Seawater
According to Sugam et.al. (8) when seawater is chlorinated, the prin-
ciple equilibrium species formed are brominated compounds analogous to chlor-
inated species produced in fresh water. In the pH range from 6 to 8 these
brominated species are HOBr, OBr", NBr.,, NHBr2> and NH^Br, The formation of
these species occur because the bromide (Br~) present in seawater is readi-
ly oxidized by chlorine.
3-11
-------
Constituent
TABLE 4. THE MAJOR CHEMICAL SPECIES IN SEA WATER
(5)
Percentage of Constituent present as each species @
25°C, 19.375%. Chlorinity, 1 atm., and pH 8.0
Chloride
Sodium
Magnesium
Sulfate
Calcium
Potassium
Bicarbonate
Bromide
Boron
Strontium
Fluoride
Na+ (97.7%); NaS04 (2.2%); NaHC03° (0.03%)
Mg2* (98%); MgS04 (10%); MgHC03 (0.6%); Mg C03° (0.1%)
SO?" (39%); NaXO" (37%); MgS04 (19%); CaS04° (4%)
Ca*+ (88%); CaS04° (11%); CaHCO* (0.06%); CaC03° (0.1%)
K* (98.8%); KSO" (1.2%)
HC03 (64%); MgHC03 (3%); CO2" (0.8%); MgC03° (6%);
NaCO; (6%); NaCO; (1%);
J J
B(OH)3 (84%); B(OH)4 (16%)
F" (50 - 80%); MgF* (20 - 50%)
3-12
-------
TABLE 5. MINOR CONSTITUENTS OF SEA WATER
Constituent
Rubidium
Aluminum
Lithium
Barium
Iodine
Silicon
Nitrogen
Zinc
Lead
Selenium
Arsenic
Copper
Tin
Iron
Cesium
Manganese
Phosphorus
Thorium
Mercury
Uranium
Cobalt
Nickel
Radium
Beryllium
Cadmi urn
Chromium
Titanium
Average Value
120
2
185
20
63
2000
280
6.5
0.05
0.2
0.46
2
0.8
6.6
0.4
1.5
30
0.05
0.03
3
0.27
5.4
8 x 10"8
5.7 x 10"4
0.113
0.3
1
Range
89 -
0 -
180 -
5 -
48 -
134
7
190
93
80
0 -4900
0 -
1 -
0.02 -
0.052 -
0.2 -
0.2 -
--
0-1
0.27 -
0.2 -
0 -
2 -
--
2 -
0.035 -
0.43 -
4 -
--
0.02 -
0.23 -
_
560
48.4
0.4
0.50
35
4
62
0.58
8.6
90
40 x 10"4
4.7
4.1
43
15 x 10"8
0.25
0.43
* Excluding dissolved gases
3-13
-------
TABLE 6. DISSOLVED ORGANIC COMPOUNDS IN SEA UATER
(5)
Constituent
Range
1. Carbohydrates
2. Proteins and Their
Derivatives - Total
Polypetldes and
Polycondensates
Free Ami no Acids
3. Aliphatic Carboxylic and
Hydroxycarboxylic Acids
4. Biologically Active Compounds
5. Humic Acid
6. Phenolic Compounds
7. Hydrocarbons
0.2 - 8.4 mg/1
14.9 - 156.5
6.9 - 39.1 Pg/l
8.0 - 117.4 yg/l
0.44 - 4.71
1.8 - 36.64 myg/1
Present
3 - pg/1
Traces
3-14
-------
Sugam further indicated that when chlorine in the form of hypochlorous
acid (HOC1) is added to seawater the oxidation of bromide would occur instan-
taneously as shown in the following exchange reaction:
HOC1 + Br" - - HOBr + Cl"
Carpenter et.al. (9) in their discussion of the reactions of chlorine
with seawater presented the following chemical equations to describe the
decay of gaseous chlorine to chloride ions. When gaseous chlorine (C12) is
added to seawater the following hydrolysis reaction would occur:
C12 + H20 --HOC1 + H+ + Cl"
Gaseous chlorine may further react with the bromide in seawater to pro-
duce the following sets of reactions (9):
Br
and
3 BrOH-BrO ~ + 3H+ + 2Br",
3
BrCl + 2C12 Br C15,
BrCU + 3 H90 ~BrO,~ + 6H+ + 5 Cl".
b L 3
In discussing the environmental toxicity of chlorine the common unit of
measure is "Free Available Chlorine" (FAC). For hypochlorous acid this unit
FAC can be represented as follows (10):
FAC = HOC1 + OC1"
Johnson (10) stated that in seawater at pH 7.5 and temperature of
298°K (77°F) the FAC is approximately half HOC1 and half OC1", and that as
the pH increases to create more basic solution, the FAC shifts towards the
hypochloride ion (OCT).
2Br"
Br,
c.
BrOH
+
+
+
ci2
H90 -
£.
ci2
Br2 +
Br OH
BrCl
2 Cl",
+ H+
+ HOC1 ;
3-15
-------
The bromlnated species formed in seawater given the above equilibrium
shift is shown in the following equation (9).
Br" + 3 CIO" > Br03~ + 3 Cl"
Johnson (11) in discussing the chlorination of seawater stated that
chlorine would react with the bromine present in natural seawater to produce
HOBr; likewise, the chlorine would react with the iodide present in natural
seawater to produce HOI. These reactions will go to completion rapidly, in
addition, further oxidation of these two species will occur resulting in the
rapid formation of I03" and the slower formation of Br03 ~.
In the presence of ammonia, bromine formed during the oxidation of bromide
by chlorine or chloramines will react with ammonia to form bromamines. The
relative quantities of bromamines and chloramines are kinetically rather than
equilibrium controlled. Because the presence and formation of these halo-
amines are a function of reaction kinetics, the predominate chloramine is
monochloramine (NhUCl) and the predominate bromamines are dibromamine (NHBr?)
and tribromamine (NBr3) (10). Sugam and Helz (8) reported that the conver-
sion of HOC1 to HOBr in seawater, in the absence of ami no-nitrogen, reaches
99% completion in less than 10 seconds at pH 8; at lower pH it reaches com-
pletion even more rapidly. Therefore, if a total conversion of chlorine to
bromine 1s assumed, Figure 4 shows that the distribution of bromine species
present in seawater is a function of both pH and the logarithm of the initial
mole ratio of ammonia to bromine. The data presented identifies species
which will be present after 1 to 2 minutes of contact time and the lines
Indicate equal equivalent concentrations (1).
Figure 5 is similar to the chart developed by Davis et.al, (12) to pre-
sent the theoretical degradation of chlorine as a result of chlorinating
natural seawater. The decay of diatomic chlorine gas occurs between levels
I and II; this reaction occurs rapidly and goes to completion within a few
seconds after the addition of chlorine. Between levels II and III the chem-
ical composition and abundance of products formed is a function of the physi-
cal and chemical parameters of the water, including, but not limited to,
temperature, pH, ammonia, and bromine available as reaction components. Spe-
cies found in level IV include halogenated organic constituents which may be
formed at either level II or III or both.
3-16
-------
I
~o
o
ID
Oi
o
-h
O
(0
CX>
r*-
»jr
O
z
re
(jj
rl-
O
en
OJ
3
a
c
6
pH
10
Figure 4. Principle species of bromine and bromamine
-------
I
CO
II
III
IV
Cl.
HOCl.OCl", NaOCl
NH2C1, NHC12, NH2Br,
NHBr2, BrO", HBrO
Halogenated Organic
Constituents
CT, Br'
Figure 5. Degradation processes for chlorine in saline waters
-------
A charge balance results as one atom of Cl passes from level I to V for
each atom of Cl that passes from level I to II, or in reduction or replace-
ment reactions in which Cl" is released at any of the other levels between I
and V.
In their discussion of the reaction of chlorine upon various organic spe-
cies Jolley et,al. (13) presents several chemical equations to describe the
formation of various chlorinated hydrocarbons. Portions of their work is
presented in the following narrative.
When chlorine reacts with organic substances such as proteinaceous mater-
ial, found in bacterial cell walls, a chlorine substitution reaction can
occur leading to the formation of N-chlorinated proteinaceous material. If
the organic substance involved in this substitution reaction is an amine the
reaction formula will appear as follows:
H
R-NH2 + HOC1 >R-NC1 + HOH
Likewise, if the organic substance involved is an amide the reaction formula
will appear as follows:
0 0
R - C - NH2 + HOC1 > R - C - NCI + HOH
The kinetics of the formation of the N-chloro compounds is considerably slow-
er with amides than with amines.
The major portion of soluble organic matter in cooling water is made up
of humic material. Humic material is a generic type of organic substance
which is classed according to solubility. These materials are complex poly-
mers which range in molecular weight from several hundred to many thousand
grams per mole. They are made up of various aromatic and alicyclic noieties
containing alcoholic,-carbonyl, carboxylic, and phenolic functional groups.
Phenols and aromatic acids are readily chlorinated in aqueous solutions by
HOC! or OC1". Chlorine substitution reactions with phenolic compounds and
aromatic organic acids are shown in Figure 6.
3-19
-------
C02H
C02H
+ HOC!
HOH
Cl
C02H
OH
HOC!
OH
HOH
Cl
CO~H
2
HOC!
Cl
Aromatic Organic Acids
OH
HOC1
OH
HOC1
OH
Phenolic Compounds
C02H
C02H
HOH
OH
Cl
+ HOH
OH
HOH
OH
Cl
Figure 6. Chlorine substitution reaction
3-20
-------
A possible pathway for chlorine substitution reactions with humic mater-
ial is the haloform reaction. This reaction appears as follows:
0 0~
R - J - CH3 > R - C = CH2 + H+
0" 0
R - C = CH2 it HOC! >R - C - CH2C1 + OH"
0" 0"
R - C - CH2C1 >R - C = CHC1 + H+
0" 0
R-C = CHC1 + HOC1 *R - C - CHC12 + OH"
0 0
-» -» R - C - CC13 + OH" >R - C-OH + CC13"
CC13" + H+>HCC13
If the haloform reaction is the primary path of chlorine substitution with
humic material the principle organic species contained in chlorinated sea-
water would in all probability be chloro-organics such as chloroforms (13).
In seawater containing significant quantities of bromide ions (67 mg/1),
humic material will react more preferentially with the bromide ions to form
bromo-organics, thus impeding chloroform formation. Since HOC1 is readily
converted to HOBr in the presence of bromide ions little or no chloroform is
expected to occur in chlorinated seawater. The mechanisms by which bromo-
form is produced is not well understood; however, reactions similar to those
postulated for chloroform formation are likely to occur. The predominant
species identified by Carpenter and Smith (14) are bromoform and, to a less-
er extent, chlorodibromomethane. According to these authors, the presence
and intensity of light and particulates will affect the production of bromo-
form; whereas temperature does not appear to be a variable.
Comparison of Identified Chlorinated Seawater Species to the list of 129
Toxic Pollutants
Data presented in previous sections of this document indicate that when
chlorine is added to seawater, bromide present in the seawater is oxidized
by the chlorine and the resulting species formed are brominated compounds
analogous to chlorinated species found in fresh water. In addition to these
3-21
-------
compounds, which are formed by replacement reactions, are a wide variety of
other species formed by a number of different types of reactions. These re-
actions and the compounds formed are dependent on the presence of various
contaminants and/or pollutants in the intake water; therefore, the composi-
tion of the chlorinated discharge water is to a large degt?e dependent upon
the composition of the original intake water. This fact in itself implies
that the composition of chlorinated discharge water is site and time speci-
fic. Some of the more typical compounds that may be found in the chlori-
nated discharge waters are bromamines, chloramines, chloroforms, bromaforms,
and halogenated organic compounds.
An example of the complexity of predicting and/or evaluating the con-
stituents found in chlorinated sea water can be shown by observing the re-
action modes and compounds formed in sea water containing N-halamines.
Kovacic et.al. (15) in their studies of N-halamines, such as N-bromamines
and N-chloramines, indicate that they may act as a stimuli for the formation
of various classes of organic compounds. They attributed this to the fact
that the nitrogen and halogen act as sites for chemical reactions and that
these reactions can occur in quite diverse manners.
Examples of the diverse reaction modes are as follows (15):
The nitrogen component may act as a cation (bicyclic rearrange-
ment), anion (hydrazine formation), radical (photolysis and addi-
tion alkanes), radical cation (Hoffman-Loffer reaction), and a
base (nucleophllic substitution).
The halogen component may act as a cationic (halogenation), anion-
ic (Grinard reaction), and radical (photolysis).
When N-H is present reactions which are typical to this structure
may also be observed.
The organo-chlorides formed by reactions such as those shown in Figure
6 are included in the list of 129 priority pollutants. These priority pol-
lutants which include chlorinated species of benzene, ethane, ether, and
phenol to name a few^ could as Jolley et.al. (13) suggests be readily form-
ed 1n a chlorinated aqueous solution provided the parent organic species
are present. Various organo-bromides analogous to these organo-chlorides
may also be formed. The formation of such species may, as Kovacic et.al.
(15) suggest , result because of the presences of organic halamines. The
brominated species do not enjoy the notoriety that organo-chlorides have
received; however, they may be as toxic.
3-22
-------
At this time no quantitative studies of chlorinated seawater have been
completed. Therefore, any prediction of exact compounds and their respec-
tive compositions would include a great deal of supposition. However,
given the proper intake conditions any one or a number of substances con-
tained in the list of 129 toxic pollutants may occur or exist in chlorinated
discharge water from power plant cooling systems. A preliminary qualitative
characterization of compounds found'in chlorinated seawater was conducted by
Bean et.al. and is presented in Section 5.0 under the heading of "Identifi-
cation of Potentially Toxic Species".
3-23
-------
SECTION 4.0
EVALUATION OF AMPEROMETRIC TITRATION FOR DETERMINATION
OF RESIDUAL CHLORINE IN SEAWATER
The determination of free and combined chlorine has historically been
done with applications in drinking ajid waste waters. The requirements and
problems associated with monitoring chlorine residuals in power plant cool-
ing waters are considerably more complex. This is particularly true when
seawater is used as the coolant. The chemistry of chlorine in seawater shows
little resemblance to that of either fresh or waste waters.
A number of methods for determining chlorine residuals are available.
The most widely accepted is the amperometric titration method. This method
for the determination of free available chlorine and combined chlorine spe-
cies in water has been considered the standard for many years. Since it was
first reported by Marks and Glass (16) in 1942 it has become the most widely
used method for chlorine determination (17,18). Recently the amperometric
titration method has become suspect when used for chlorine determinations
in seawaters (11,19).
This section provides; (1) a general discussion of the amperometric
titration method; (2) a brief discussion of iodine chemistry as it relates
to chlorine determinations in seawater; and (3) an assessment of the methods
accuracy, precision and interferences when used in seawater determinations.
Areas where further research is required and a brief discussion of alterna-
tive methods is also included.
General Method Description
Amperometric titration has been used to determine total residual chlor-
ine and also to differentiate between free and combined available chlorine
in all types of waters. Two slightly different techniques are employed; a
forward titration (generally considered the standard), and a backward titra-
tion. The difference is in the order of chemical additions. In the back ti-
tration, phenylarsineoxide (PAO) is added in excess and a biiodate solution
is used as the titrant; whereas in the forward titration biiodate is added
4-1
-------
1n excess and PAO is used as the titrant. This section will deal only with
the standard forward titration method. The interferences and limitations
are similar between the two methods.
The principle of amperometric titration is an adaptation of polarogra-
phic principles. When the cell of the titrator is immersed in a sample con-
taining chlorine or other oxidants, current is generated; but as phenylarsine-
oxide is gradually added, the chlorine is neutralized and the generation of
current ceases. The determination of free available chlorine is done between
pH 6.5 and 7.5. In this pH range reaction of combined chlorine is slow. For
the determination of combined chlorine, potassium iodide (KI) and buffers are
added in the proper amount to buffer the solution to pH 3.5 to 4.5 and acti-
vate the slower reacting species. Monochloramines react more readily than
dichloramines; this tendency provides a means for determining the two species.
The addition of a small amount of KI (in the neutral pH range) enables an
estimation of monochloramine concentration. Reducing the pH to the acid range
while increasing the KI concentration allows for the separate determination
of dichloramine content.
i
Phenylarsine oxide (PAO) is used as the reducing agent (the titrant in
forward titrations, and added in excess in back titrations) for free chlor-
ine or \2 determination by the following reactions (20):
C6 H5 As 0 + C12 + 2H20 ~*-C6 H& As 0(OH)2 + 2 HC1
C6 H5 As 0 + I2 + 2H20*-C6 H5 As 0(OH)2 + 2 HI
The PAO is stable even in dilute solutions. A special amperometric cell is
used for detection of the end point. The cell unit is connected to a micro-
ammeter and recorder for end point determination. The cell unit generally
consists of a noble metal electrode and reference electrode.
Numerous variations of amperometric titration setups are in use in dif-
ferent labs or produced by different instrument manufacturers. Instrument
manufacturers have provided automated titration apparatus for the chlorine
determination for many years. Primary application has been to drinking and
waste waters. The analytical requirements are for the measurement of mini-
mum chlorine residuals in drinking and waste waters as applied to disinfec-
tion. Power plants cooling waters however, are required to be monitored for
maximum chlorine residuals for the protection of aquatic organisms near the
discharge point. This fact makes it necessary for power plant monitors to
analyze chlorine residuals more accurately at lower levels.
4-2
-------
Iodine Chemistry
The use of iodide salts in the determination of chlorine species is
primarily to catalyze normally sluggish or negligible response to certain
oxldant fractions. The salts are also employed to control ionic strength,
to retard volatilization, or to serve other functions. The iodide salts
are used in all the generally accepted analytical methods. Therefore, er-
rors introduced by imperfect iodine behavior will effect all methods.
The generalized iodide - halogen produced oxidant reaction can be
written as:
R-X + 21" + H"1" »-I2 + R - H + X"
where X represents a halogen atom. For strong oxidant (e.g., HOC1 , HOBR
or NH2 Cl) the reaction proceeds to the right even at neutral pH. For more
inert oxidant (e.g., NHC12) the reaction is accelerated only by the addi-
tion of I" and H+ ions. It is this principle which allows for the selective
determination of different oxidant fractions.
It is important to note that all bromine oxidant species, which may
be present in chlorinated seawater, are unstable with respect to the iodine
species. They are all capable of reacting quantitatively with I" to form
Io, \2~ and lOo". although the reaction rates for several oxidant species
conversions are not known. The relative concentrations of iodine species
is represented by the following equation:
In amperometric titrations this is extremely important because the elec-
trode is most sensitive to I2 (2l)
Many potential sources of error may enter into the analysis of chlor
ine produced oxidants at low concentrations due to iodide reactions with
chlorinated seawater. Among these potential sources of error are: those
from naturally occurring iodate in the seawater ; other oxidants; volatili
zation and reaction with organic matter. Only the first two will be dis-
cussed here. Volatilization is considered a technique error and can be
minimized by proper handling and prompt analysis of the sample. Organic
matter is a more common interference in wastewaters than in seawater.
4-3
-------
Natural seawater contains about 0.06 mg/1 of elemental iodine. Fresh
water lakes and rivers contain considerably less (on the order of 0.002 mg/1).
Wong and Brewer (22) have reported that the primary iodine species in oxygen-
ated surface seawater is I03~. Thus if the analysis is performed by a method
which measures I03~, then a background level will be measured. In the case
of amperometric titration 10," is too inert to be detected, however, when the
KI solution is added the I03" will react to form I2 which will be detected.
Fabian (23) and Carpenter, et.al. (19) both report this occurrance and Fabian
presents rate equations for the reaction.
There are many potentially interferring oxidants which can occur in
chlorinated seawater. Table 7 lists some of these. Fortunately these will
react only slowly under normal analytical procedures. However proper tech-
niques must be employed at all times if gross interferences are to be mini-
mized.
TABLE 7. POTENTIAL INTERFERRING
OXIDANTS
S2082" Br C12
NBr
Br2
HOBr NHBr
Mn04 Br2
2
OBr" NH2Br
Br03" HNO
Mn04" Cu+22
Mn02 Fe+3
Br C10"
4-4
-------
Limitations and Interferences
The limitations and interferences to which the amperometric titration
method is subject are dependent upon the specific chemical species present
in the water being analyzed. The species which may be found in chlorinated
seawaters have been identified in Section 3.0. Those interferring compounds
associated with the iodide chemistry have been discussed in the preceding
paragraphs. This section consists of a review of the accuracy and precision
of the method; the specific chemical interferences; the mechanisms by which
they affect the determination and the specific interferences as they relate
to seawater chlorination.
Accuracy and Precision
The amperometric titration method requires a high degree of operator
skill for accurate results. The method is susceptible to mechanical as well
as chemical interferences. Crecelius, et al., (24) in an as yet unpublished
study, reports errors caused by different methods of handling and treating
samples. The order of addition of chemicals was of major significance in
introducing errors to the analysis. Crecelius recommended the mixing of KI
with buffer before addition of the sample. Other mechanical errors may be
introduced by exposure to light and volatilization of sample and reagents.
These all may be minimized by proper analytical techniques and careful and
prompt analysis of the sample.
Due to the highly unstable nature of chlorinated water samples only
limited testing of the procedure by multiple laboratories have been under-
taken. One such study, reported in Standard Methods (17), involved the ship-
ping of solid synthetic unknowns. The individual laboratories mixed the sol-
ids following instructions and then immediately performed the analysis. Re-
sults of this study (which involved only fresh water and therefore shoul'd be
considered to represent the best accuracy and precision obtainable by the
method) indicate that the relative error, between laboratories, for the de-
termination of free chlorine was 25% and for total available chlorine was 8.5
to 8.8%. Standard deviations, among the laboratories were 42.3% for free
chlorine and 12.5 - 24.8% (dependent upon concentration) for total available
chlorine. These values were for levels of chlorine from 690 to 1830 vg/1-
Components present in chlorinated seawaters which cause interference to the
4-5
-------
method may act to both reduce efficiency and increase the standard deviation.
Several alternative methods exist for the determination of chlorine,
some of these methods are: chlorine flux monitor, membrane probe amperome-
try, specific ion electrode, iodometric methods, DPD (and other colorime-
trlc methods) and others. Each is considered less accurate or reliable than
the amperometric titration method. The DPO-Ferrous titrimetric method has '
been mentioned as valuable in that it detects only free chlorine. However,
1n seawater where Br" is present, this selectivity is reduced. It may not,
by present analytical methods, be possible to determine only free chlorine
residuals in seawater.
Further research into the accuracy and precision of amperometric titra-
tion, and other analytical methods, are required. Studies specifically
directed to monitoring chlorine in seawaters are needed, and only recently
have programs been undertaken, A report, prepared for EPRI by the Public '
Service Electric and Gas Company and the University of Maryland, which is
near release,looks critically at many of these methods as they relate to
seawater. In addition, a recent study, currently under investigation by
the power industry, evaluates the accuracy and precision of the ampero-
metric titration method at four selected power plants utilizing different
types of waters for cooling. Two of these cooling waters are from fresh
water sources; one from esturine waters; and one from seawaters. Eight
to ten participants, all using their own amperometric instruments, are
analyzing identical samples at each of the four sites. Data are currently
being compiled and, unfortunately, are not available for incorporation in
this report. The development of more precise methods for chlorine deter-
minations are also necessary if it is concluded that chlorine is the major
toxic material needing monitoring. Section 5.0 of this report presents
toxicological data and makes some recommendations as to which compounds are
toxic and at what levels.
Chemical Interferences
Standard Methods (17) identifies compounds which interfere with the
analysis of chlorine compounds by the amperometric titration method. The
Interferences identified are for fresh or wastewaters and do not include
4-6
-------
compounds found in seawater. Accurate determinations of free chlorine are
not obtainable in the presence of nitrogen trich^onne (NCl^) or chlorine
dioxide (17). Both of these species titrate partially as free chlorine.
NCK also titrates partially as dichloran.ine ciusing positive errors to both
these fractions. Seawater nitrogen however, is rarely in the form of NCK.
During each determination organic chloraniines are also partially titrated.
Mono- and di-chloramines interfere in a positive manner with each other (17).
Copper and silver (as sulfate and ions respectively) can cause inter-
ference. Copper interferes by plating out on the electrodes and has been
noticed after heavy copper sulfate treatment in reservoirs. Silver ions
act to poison the electrode (17). Concentrations of these metals in sea-
water are generally very low, thus have little interference.
At pH 7 and no KI (the conditions traditionally used for free chlorine
detenmnations) other free halogens, specifically bromine are detected. Be-
cause seawaters contain relatively high concentrations of bromide ions,
which when chlorinated form free bromine, this is of major importance (25).
At these conditions bromamines and HpOo give non-quantitative responses also
(25). Bromamines are common chlorinated seawater constituents where amines
are present in feed waters. The bromamine reaction in the titration is
relatively slow; this may reduce the interference and accounts for the non-
quantitative nature of the interference. The presence of H^Op has not been
confirmed in any significant quantities however.
Other compounds which have been reported to cause interferences in-
clude Br CL" and Cl On"". These give non-quantitative results at pH 4.2 with
250 mg/1 KI added. Free bromines, chlorine, chloramines, bromamines and
Hp02 are also determined (25). The non-quantitative nature of many of these
interferences make them impossible to remove.
Interferences Particularly Related to Seawater
Many of those compounds identified in Section 3.0 as typical of chlor-
inated power plant seawaters are also compounds which interfere with the
amperometric titrations. Some of these, specifically bromamines, are the
dominant species in chlorinated seawaters. These interferences make it
impossible to clearly separate free chlorine and bromine from the interfer-
4-7
-------
ring species. The non-quantitative nature of these interferences make even
the determination of total oxidant by the amperometric titration method a
formidable task.
The data available on the amperometric titration method, as it is ap-
plied to determinations in seawater, does not allow for quantitative deter-
minations of accuracy and precision. There are at present no accepted methods
for eliminating the effects of the interferring compounds. It is likely that
totally new procedures will need to be developed if the acutal quantities of
free chlorine residuals need be known. Section 5.0, which discusses the tox-
idty of various compounds from chlorination of seawater, indicates that many
other compounds are also toxic. The amperometric titration method may be suf-
ficient to determine levels of total oxidants (primarily bromine and halo-
genated amines) that are potentially toxic in cooling water discharges.
These values, however, should not be confused with free chlorine residuals.
4-8
-------
SECTION 5.0
TOXICITY OF COMPOUNDS FORMED BY CHLORINATION OF SEAWATER
This section identifies and discusses the various chemical species
formed, their relative toxicities, and the specific marine organisms af-
fected by the addition of chlorine to seawater. Particular emphasis is
placed on those chemical species identified as typical of or likely to be
present in power plant cooling water discharges as delineated in Section
3.0.
Definition of Toxicity
Prior to introducing and discussing toxicity it is necessary to become
familiar with the terminology commonly used in the field of toxicology.
There are several ways to define and categorize toxic effects, as well as,
a number of techniques used for conducting toxicity tests. Likewise, the
results of these toxicity tests are expressed several different ways. The
following tables: 8, 9, and 10, originally presented by Burton (26), sum-
marizes the most commonly used methods of categorization, testing technolo-
gies and the terminology used to report results.
Table 8 identifies the general categories of toxic effects. By simpli-
fying the information contained in this table it is possible to form two
general categories of toxic effects:
Acute toxicity which is generally lethal
Chronic toxicity which may be either lethal or sublethal.
The other categories listed are used more as descriptive words to iden-
tify the degree and effects of toxicity on the test organism.
5-1
-------
TABLE 8. GENERAL CATEGORIES OF TOXIC EFFECTS
Acute - Involving a stimulus severe enough to bring about a re-
sponse speedily, usually within two to seven days for fish.
Subacute - Involving a stimulus which is less severe than an acute
stimulus, which produces a response in a longer time, and may
become chronic.
Chronic - involving a stimulus which is lingering or continues for
a long time, often used for periods of about one tenth of the
life span or more.
Lethal - causing death, or sufficient time to cause it, by direct
action.
Sublethal - below the level which directly causes death.
Cumulative - brought about, or increased in strength, by succes-
sive additions at different times or in different ways.
Delayed - symptoms do not appear until an appreciable time after
exposure-, often the response is triggered by occurrence of
some other stress.
Short-term - acute but more indefinite
Long-term - chronic but more indefinite.
Table 9 gives the four techniques generally used for conducting toxi-
city tests. These are laboratory tests that may or may not produce similar
results as in a natural marine environment. It is recommended that only the
continuous flow or flow-through technique be used for chlorine toxicity stu-
dies with macroinvertebrates and fishes, with exception to chlorine decay stu-
dies where exposure periods are relatively short.
5-2
-------
TABLE 9, TECHNIQUES GENERALLY USED FOR CONDUCTING
TOXICITY TESTS
Static Technique - test solutions and test organisms are placed in
test chambers and kept there for the duration of the test.
Static Recirculation Technique - similar to the static technique
except that each test solution is continuously circulated
through an apparatus to maintain water quality by such means
as filtration, aeration, sterilization and returned to the
test chamber.
Static Renewal Technique - similar to the static technique except
that the test organisms are periodically exposed to fresh
test solution of the same composition usually once every 24
hours by transferring the test organisms from one test cham-
ber to another.
Continuous Flow or Flow-Through Technique - test solutions flow in-
to and out of the test chambers on a once-through basis for
the duration of the test. Two procedures can be used: (1)
large volumes of the test solutions are prepared before the
beginning of the test and these flow through the test cham-
bers and (2) fresh test solutions are prepared continuously
or every few minutes in a toxicant delivery system.
Table 10 presents the terminology most commonly used for expressing the
results of toxicity tests. It should be noted that time and concentration
are inseparably linked in toxicity tests; hence, time should be stated in
order to give meaning to the toxicity data being reported, e.g. 24-h LD50,
which is the dose of a toxicant which is lethal to 50% of the test organ-
Isms in 24 hours. The ILC50 term is ambiguous and should incorporate two
additional terms to fully express the test results, e.g. 96-h ILC50 (3,180)
where the 3 would represent the number of exposures and the 180 would be the
total exposure time.
5-3
-------
TABLE 10. TERMINOLOGY USED FOR EXPRESSING RESULTS OF
TOXICITY TESTS
LC50 - median lethal concentration of a toxicant in solution which
is lethal to 50% of the test organisms.
LC50 - median effective concentration of a toxicant in solution at
which a response other than death occurs to 50% of the test
organisms.
LD50 - median lethal dose of a toxicant within the organism which
is lethal to 50% of the test organisms. ,
ED50 - median effective dose of a toxicant within the organism at
which a response other than death occurs to 50% of the test
organisms.
LT50 - median lethal time. Used for mortality time in fixed concen-
trations.
i
ET50 - median effective time. Used for response time other than
death in fixed concentrations,
TLm, TLm, TLjjg, TL50 - median tolerance limit. Term used primarily
by U.S. pollution biologist. Equivalent numerically to LC50.
LL50 - median lethal level. For tests which yield mortality data
where neither concentration or dose applies, e.g. tests with
temperature.
EL50 - median effective level. For tests which use a response
other than death where neither concentration or dose applies,
e.g., tests with temperature. ,
ILC50 - intermittent lethal concentration of a toxicant in solu-
tion which is lethal to 50% of the test organisms during in-
termittent exposure tests.
(Continued)
5-4
-------
TABLE 10. (Continued)
Other terminology - usually used to describe the concentration at
which toxicity ceases or the point beyond which 50% of the
population can live for indefinite time:
Incipient lethal level
Ultimate median tolerance limit
Lethal threshold concentration
Median threshold concentration
Asymptotic lethal concentration
Asymptotic threshold concentration
Others
Identification of Potentially Toxic Species
It should be noted that chlorine, itself, is toxic to most aquatic or-
ganisms. For this and other reasons chlorine is perhaps the most widely
applied chenical for biofouling control in power plant cooling systems.
White (20) reported that current biofouling practices for various cooling
circuits in power plants involve two simultaneous types of chlorination:
continuous and intermittent. Continuous, low level chlorination (concentra-
tion typically 0.25 to 0.50 mg/1 (ppm) ) is used to control hard shell or-
ganisms; and intermittent chlorination (concentration typically 1.0 mg/1
(ppm) ) is used to control soft form organisms. These chlorine concentra-
tions within the cooling circuit will normally control and/or curtail bio-
fouling problems.
As noted in Section 3.0 (Characterization of Chlorinated Seawater) it
is difficult, at best, to predict the products formed by chlorinating natur-
al seawater. This is due to a number of controllable and uncontrollable
factors which include: (1) the chemical composition of the seawater (espe-
cially ammonia and organic amines); (2) the amount of chlorine added; (3)
the reaction duration; and (4) pH and temperature. However as noted, the
equilibrium species formed are expected to be predominantly brominated com-
pouj\ds analogous to chlorinated species produced in fresh water.
*> 5-5
-------
Preliminary studies conducted by Sugam (8) and Johnson (11) indicated
that brominated compound, such as organic and inorganic bromamines, are formed
1n chlorinated seawater and that these brominated species may have toxic ef-
fects. Their work has been substantiated by the preliminary results of Bean
et.al. (27) in their analysis of chlorinated seawater discharged from a sys-
tem similar to a power plant cooling circuit.
A cursory list of the chemical compounds which Bean et.al. (27) Identi-
fied as being present in chlorinated seawater is given in Table 11. Because
this 11st is preliminary it is expected that the number and types of compound
identified will greatly increase as more data become available.
The toxicity of the various chemical species (particularly brominated
compounds) which may be formed as a result of seawater chlorination has not
been established; however, Bean (27) found that the principal constituents
found 1n chlorinated seawater is bromoform which is one of the compounds
identified in the list of 129 priority pollutants. Various other brominated
substances lisrted in Table 11 such as bromo biphenyls are also contained in
the same list, and bromonaphthalene which have a chlorinated analog are also
contained in this list.
The fact that those compounds identified by Bean et.al. (27) are so
closely linked to species that have been previously identified as being tox-
ic 1s indicative, that the conclusion reached by Sugam and Johnson, of many
of the brominated species formed will be toxic may be indeed correct.
TABLE 11. A PRELIMINARY LIST OF THE CHEMICAL CONSTITUENT
IDENTIFIED IN CHLORINATED SEAWATER
1.
2.
3.
4.
b.
6.
7.
8.
9.
Bro.no form
Tri we Uiyl benzene
Naphthalene
Bromotriii.e thy 1 benzene
2-Mothylnaphthalene
1 f'.L'tbyl naphtha! ene
Riphenyl
Broinotetraline
Broniotetroniclhyl benzene
10. Dimethyl naphthalenes
11. Bromonaphthalene
1?. Bromomethylnfiphth.il cues
13. Bromobiphcnyls ami
Broiiiodimethyl naphthalenes
14. Phcnanthrene
If). bron;othmethyl naphthalene
16. Phthaliite Ester;
17. Pyrene
18. Bromoaceval
5-6
-------
Identification of Toxic Levels and Aquatic Organisms Affected
This sub-section presents information on the to;
-------
TABLE 12. SUMMARY OF DATA ON TOXICITY OF CHLORINE TO MARINE ORGANISMS
I
ro
Data Point and Descriptive
Scientific Name Name
Plants:
N.G. Phytoplankton
N.G. Phytoplankton
Chlorophyta
Chiamydomonas sp.
Dunaisella terliolecia
Chrysophyta
Asterionella Japonica
Asterionella japonica
Chaetoceros decipiens
Chaetoceros didymum
Delonula confervacea
Skeletonema costatum
Skeletonema costal um
Thalassiosira nordenshoikii
Thalassiosira Pseudonana
Thalassiosira pseudonana
Thalassiosira pseudonana
Thalassiosira rotula
Chrysophyceae
Monochrysis lutheri
Rhodomonas baltica
Concen-
tration
(mg/1)
0.1
0.03
1.5
0.11
0.4
0.2
0.14
0.125
0.8
0.095
0.6
0.195
0.075
0.2
0.5
0.33
0.2
0.11
Duration
(min)
240
N.G.
5-10
1,440
0.27
2
1,440
1,440
0.6
1,440
1.7
1,440
1.440
6.8
0.3
1,440
1,440
- 1,440
Effect
71% decrease in productivity
50% decrease in photosynthesis
Decreased grwoth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
50% decrease in growth
(Continued)
-------
TABLE 12. (Continued)
tn
Phaeophyta
Macrocystis pyrifera
Invertebrate animals:
Cnidaria
N.G.
Bimeria franciscana
Annelida
Phragmatopoma californica
Phragmatopoma californica
Mollusca
Crassostrea virginica
Crassostrea virginica
Crassostrea virginica
Ostrea edulis
N.G.
Mylilus edulis
Mylilus edulis
Mytilus edulis
Crepidula and Littorina
Acartia tonsa
Acartia tonsa
Acartia tonsa
Acartia tonsa
Acartia tonsa
Eurylemora affinis
Eurylemora Affinis
Giant kelp
Sea anemone
Hydroid
Polychaete worm
polychaete worm
Oyster
Oyster
Oyster
Oyster larvae
Oysters
Mussel
Mussel
Mussel
Gustropods
Copepod
Copepod
Copepod
Copepod
Copepod
Copepod
Copepod
5-10 5,760 50% decrease in photosynthesis
1.0 21,600 No effect
2.5 180 Slight decrease in growth
0.2 5 17% decrease in sperm motility
0.4 5 70% decrease in sperm motility
0.2 N.G. ".46% decrease in ciliary beat
rate
1.0 20-90 Pumping threshold
0.18 4,320 50% decrease in time open
0.5 2 Swimming stopped
2.5 10 No effect (30°C)
1.0 21,600 100% mortality
2.5 7,200 100% mortality
0.02-0.05 N.G. Young won't attach-attached
ones will move
0.2 N.G. Stops growth
0.75 2 30% mortality @ 20°C after
96 hr
0.75 2 70% mortality @ 25°C after
96 hr.
1 120 50% mortality
10.0 0.7 50% mortality
2.5 5 90% mortality-after 3 hr.
1 300 50% mortality
10.0 2 50% mortality
(Continued)
-------
TABLE 12. (Continued)
Pseudodiaptomus coronatus
Pseudodiaptomus coronatus
Balanus improvisus
N.G.
Elmlnlus modestus
Elminius modestus
Corophlum sp.
Gamnarus tlgrinus
Melita nilida
Mellta nilida
Callinecles sapidus
Callinecles Sapidus
Crangon septemspinosus
Crangon septemspinosus
Crangon septemspinosus
Palaemonetes pugio
Ectoprocta
Bugula sp.
Bugula sp.
Echinodermata
Strongylocentrotus pur-
puratus
Urechis caupo
Urechis caupo
Chordata
Botryllus sp.
Molgula sp.
Copepod
Copepod
Barnacle larvae
Barnacles
Barnacle nauplii
Barnacle nauplii
Tube dwelling
amphi pod
Amphipod
Amphipod
Amphipod
Blue crab
Blue crab
Sand shrimp
Sand shrimp larvae
Sand shrimp larvae
Grass shrimp
Sea urchin
Echiuroid
Echiuroid
2.5
10
2.5
1.0
0.5
1
10
2.5
2.5
2.5
10
0.1
0.15
5
10
2.5
2.5
10
0.125
0.2
0.4
10
1
45
5
5
21,600
10
10
410
180
120
5
1,140
5,760
900
10
5
180
2,880
1,440
5
5
1,440
4,320
50% mortality
50% mortality
80% mortality-after 3 hr.
Most dead
Threshold mortality
Heavy losses-no growth
No mortality after 24 hr.
25% mortality after 96 hr.
50% mortality
Some mortality
50% mortality
50% mortality
50% mortality
42% mortality
55% mortality
98% mortality-after 96 hr.
100% mortality
100% mortality
1-6% fertilization success
78% fertilization success
0% fertilization success
100% mortality
100% mortality
(Continued)
-------
TABLE 12. (Continued)
en
i
Vertebrate animals:
Pleuronectidae
Limanda ferruglnea
Pleuronectes platessa
Pleuronectes platessa
Pleuronectes platessa
Pleuronectes platessa
Pseudopleuronectes
americanus
Pseudopl euronectes
americanus
Pseudopl euronectes
americanus
1 Salmonidae
Oncorhynchus gorduscha
Oncorhynchus gorduscha
Oncorhynchus gorduscha
Oncorhynchus kisutch
Oncorhynchus tshawytscha
Oncorhynchus tshawytscha
Oncorhynchus tshawytscha
Oncorhynchus tshawytscha
Oncorhynchus tshawytscha
N.G.
Atherinidae
Menidia mem'dia
Menidia menidia
Yellowtail flounder
Plaice larvae
Plaice larvae
Plaice larvae
Plaice larvae
Winter flounder
Winter flounder
Winter flounder eggs
Pink salmon
Pink salmon
Pink salmon
Coho salmon
Chinook salmon
Chinook salmon
Chinook salmon
Chinook salmon
Chinook salmon
Young salmon
Atlantic silverside
Atlantic silverside
2.5
0.028
0.05
0.075
0.25
2.5
10.0
10.0
0.05
0.5
0.25
0.08
0.1
0.25
1.0
0.5
0.25
0.05
0.58
1.2
1,440
5,760
460
75
4,320
15
0.3
20
5,760
7.5
15
7,200
60
130
23
7.5
30
33,123
90
30
50% mortality
50% mortality
50% mortality
50% mortality
Mortality threshold
50% mortality
50% mortality
No mortality
\
50% mortality
50% mortality (13.6°C)
50% mortality (13.6°C)
50% mortality
Distressed-no mortality
Mortality threshold
Mortality threshold
50% mortality (11.7°C)
50% mortality (11.7°C)
Threshold mortality
50% mortality
50% mortality
(Continued)
-------
TABLE 12. (Continued)
Clupeldae
Alosa aestl vails
Alosa aestivalis
Brevoortia tyrranus
Brevoortia tyrranus
Brevoortia tyrranus
Brevoortia tyrranus
Brevoortia tyrranus
Blueback herring
Blueback herring
Atlantic menhaden
Atlantic menhaden
Atlantic menhaden
Atlantic menhaden
Atlantic menhaden
larvae
0.67
1.2
0.22
0.7
0.21
1.2
0.5
60
15
60
10
300
30
3
50% mortality
50% mortality
50% mortality
50% mortality
50% mortality
50% mortality
0 mortality
CJl
I
ro
Gasterosteidae
Gasterosteus aculeatus
Ameiuridae
Ictalurus catus
Cyprinidae
Notemigonus chrysoleucas
Bothidae
Paralichthys sp.
Mugilidae
Mugil cephalus
Miscellaneous
N.G.
Threespine stickle- 0.09-0.13
back
White catfish
Golden shiner
Flounder
Striped mullet
juveniles
Marine fish
0.1
0.03-0.23
0.3
0.3
r.o
5,760 50% mortality
2,880 50% mortality
5,760 50% mortality
5 Threshold mortality
5 Threshold mortality
1 Slight irritant response
-------
TABLE 13. SUMMARY OF THE TOXICITY OF VARIOUS CHEMICAL SPECIES TO MARINE ORGANISMS
OJ
Chemical
Compound
Chlorine
-
Chlorine
Chlorine
Chlorine
Test
Organism
Mussels
Barnacles &
sea anemones
Tunicates &
bryozos
Oncorhynchus
kTsutch
0. tshawytscha
0- gorbuscha
0. kisutch
Kuhlia
sandvicensis
Crassostrea
virgTmca
(oyster)
- -
Concen-
Test tration
Conditions (ppm)
CB.FS 2,5
1.0
10.0
10.0
10.0
CB.LS 0.08-0.1
=0.05
0.05
0.05
LS 1.0
10.0
CB.LS 0.01-0.02
0.2
. 0.01-3.0
0.01-0.05
Remarks
Total kill, 5-8 days, constant
exposure, all organisms
Some barnacles, all anemones
alive after 15 days.
All tunicates and bryozos killed,
1 hr/day exposure.
Incomplete kill of adult mussels
& anemones, h r/day exposure.
Some barnacles survived, 4 hr/day
exposure.
"Critical level" for 3-day exposure,
all species.
"Lethal limit," up to 23 days,
all species.
Maximum nonlethal .
Maximum nonlethal .
Slight irritant response. Violent
irritant response. (2 min exposure)
Sensitive to initial exposure, reduce
pumping and close valves; later develop
tolerance.
Reduce beat frequency of cilia, 21-22 C.
Causes no injury to tissue.
Interfers with normal functioning.
(Continued)
-------
TABLE 13. (Continued)
Chlorine
tn
Chlorine
Chlorine
Chlorine
Chlorine
Chlorine
Elminius SB,LS
modestus
(barnacle
nauplii)
Ostrea edulis
(oyster larvae)
"fish"
Hacrocystis CB,LS
pyri f ers
(marine Kelp)
"phytoplankton" LS & FS
(estuarine)
Bimeria CB.LS
franciscana
(hydroid)
Cnlamydomonas sp. SB,LS
(marine
plankton)
Skeletonema
costatum
(marine
plankton)
0.5
1.0
2.5-5.0
3.0-6.0
0.11-0.13
1.0
5-10
4.5
1.15
20.0
0.40-0.65
2.0
10 min exposure, "little effect."
"Significant decrease" in survival
after 10 min exposure.
10 min exposure, "little harm" at
temperatures as high as 30°C.
12 & 20 min exposures, "little
effect;" = 19 C.
Lethal.
No effect on photosynthesis, 5
days.
50% reduction of photosynthesis, 4
days.
Concentration not measured; 50-91%
reduction of photosynthesis after
passing through power plant believed
due to chlorine.
No effect after 3 hr exposure.
Time-lag in growth, 5-10 min exposure
Growth affected, recovered in 9 days.
Adverse effect on growth, 5 min
exposure.
No growth 30 days after treatment.
(Continued)
-------
TABLE 13. (Continued)
Chlorine
Sodi urn
hypochlorite
(chlorox)
Sodium
pentachloro-
phenate
Sodi um
pentachloro
, phenate
en
Sodium
pentachloro-
phenate
"marine FS
organisms"
Kuhlia LS
sandvicensis
Kuhlia LS
sandvicensis
Crassostrea gigas LS
(oyster)
Mylilus LS
edulis
(bay mussel)
0.5
10.0
2.0
20.0
0.027
0.069
0.11
0.20
0.20
0.30
0.30
0.4
0.4
Continuous chlorination controls
marine organisms ; 5-6 ppm used during
shut-down. (Methods appliec are des-
cribed)
Violent reactive response.
Violent reactive response (L min
exposure).
Medium reaction, 2 min exposure
4.3% abnormal embryos in 48 hr.
x
72.4% abnormal embryos in 48 hr.
100% abnormal embryos in 48 hr.
12% abnormal embryos, 28 ppt
salinity
21% abnormal embryos, 24 ppt
salinity
17.6% abnormal embryos, 28 ppt
salinity
33.6% abnormal embryos, 24 ppt
salinity
22.1% abnormal embryos, 28 ppt
salinity
69.1% abnormal embryos, 24 ppt
salinity
(Continued)
-------
TABLE 13, (Continued)
en
i
Pentachlorophenol Macrocystls LS
pyritera
Sodium
pentachloro-
phenate
(Sanobrite)
Sodium
pentachloro-
phenate
(Santobrite)
Bromine
(kelp)
Macrocystis CB.LS
pyri tera
(kelp)
"mussel, anemones, SB, IS
barnacles"
CB.LS
Kuhlia LS
sandvicensis
2,66
1.0
0,3
0.1
1.0
10.0
1.0
1.0
10.0
Eliminated all photosynehesis in 4
days.
Eliminated photosynthesis in 2 days.
50% inactivation of photosynthesis
in 4 days
Ineffective.
Killed all organisms, 3 days.
Killed all anemones, tunicates, and
bryozos in 1 day; all barnacles in
3 days, all mussels in 5 days.
Killed all tunicates and bryozoa in
1 day; all anemones, mussels and
barnacles in 4 days.
No irritant response, (2 min exposure)
Violent irritant response.
LEGEND:
SB =
CB =
LS =
FS =
Static bioassay
Constant-flow bioassay
Lab study
Field study
-------
In his discussion of the toxicity of chlorine on aquatic life,Brung (30)
cited a laboratory study with synthetic seawater. This study demonstrated
that phytoplankton (Cyclofella nana), when exposed to residual chlorine
concentrations of 0.150 mg/1 for more than 10 to 20 minutes, showed in-
hibited growth patterns. With residual concentrations of chlorine great-
er than 0,45 mg/1 for 6 seconds exposure time, similar growth inhibition
patterns occured.
In recent studies conducted by Goldman et.al. (31) it was found that the
metabolic activity of larval zooplankton was seriously affected at chlor-
ine residual levels below the level of detectablHty (< 0.01 mg/1). This
was found as a result of exposing the larvas to chloramine in concentra-
tions < 0.01 mg/1 for 30 minutes under controlled conditions.
Another recent study by Erickson and Freeman (32) evaluated the effect
of various chlorinated and brominated compounds on four species of marine
phytoplankton. They studied the toxic effect of chloroform and bromo-
form on the phytoplankton and found no noticeable impact occurred at
concentration of 32 mg/1 for either compound. However they discovered
that monochloramlne inhibits cell division at concentration as low as
0.125 mg/1 utilizing seawater under laboratory controlled conditions.
Given the above information and data presented in the earlier portion
of this document, it is expected that various organo-bromides analogous to
the organo-chlorides discussed in Section 3.0 (Characterization of Chlori-
nated Seawater) will be formed. The toxicity of these brominated species
on aquatic organisms have not been clearly established. However, since tox-
icity 1s a function of concentration and time, and since bromamines are more
labile as a group than chloramines and are more readily reduced to their con-
stituents (Johnson (11) ^one could make the supposition that brominated spe-
cies may not be as toxic as the chlorinated analogs. Assuming that both
species are present in equivalent concentrations, and that both have com-
parable toxicitles, the brominated species will decay more quickly and con-
sequently its toxic effect will be dissipated more rapidly.
Actual toxicity information on the various species formed in chlori-
nated seawater is scarce. Currently, Battelle Pacific Northwest and the
University of Maryland are conducting independent studies to evaluate the
5-17
-------
toxicity of compounds formed by chlorinating seawater. The Battelle study
Involves the comparative assessment of toxicity between chloroform and bromo-
form on aquatic organisms. Four marine water organisms (Quahaug, East Coast
Oyster, White Shrimp and Atlantic Menhaden), are being evaluated for bromo-
form toxicity. Concurrently four freshwater species of fish (Blue Gill,
Small Mouth Bass, Channel Catfish and Rainbow Trout) are studied for their
reactions towards chloroform. Both of these are in-situ,continuous flow
through studies. Although preliminary data have been compiled, actual find-
Ings or conclusions are not currently available for inclusion in this report.
The University of Maryland was conducting similar biological studies except
their effort was directed preimarily at evaluating the "net toxic effects"
of chlorinated seawaters from power plants. The completed report of their
studies have not been published at this time. Preliminary communications
with the author revealed that: (1) bromoform may not be the most toxic con-
stituent from seawater chlorination because of its high volatility; further
studies are needed to characterize other brominated species; (2) Blue Crabs
are most tolerant to chlorination or products of chlorination; (3) oysters
and their larvae, being the most sensitive species to chlorination, are more
susceptible to chlorine toxicity at lower than at higher concentrations.
This 1s due primarily to oysters' inability to detect low chlorine dosages
and their ability to biosynthesize anaerobically under stress or at high
chlorine dosages.
Comparison of Toxic Levels with Levels Expected from Power Plant Discharges
In his discussion of continuous chlorination as applied to power plant
cooling circuits, White (20) stated that, to achieve adequate biofouling pro-
tection, the concentration levels of free chlorine residual at the condenser
tailpipes should be maintained at 0.25 to 0.50 mg/1 (ppm). As previously
noted, at these levels, chlorine has toxic effects on certain marine organ-
Isms. These levels are within the cooling circuit, and the typical power
plant cooling circuit is designed to retain the cooling water from 5 to 10
minutes. Because of chlorine demand and/or decay, the majority of the free
chlorine residual will combine with other seawater components and form new
chlorinated organic species.
5-18
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In papers presented by Sugam (8) and Johnson (11), the decay of chlorine
by oxidation-reduction reactions with various halides and ami no-nitrogen com-
pounds present in seawater was discussed. Both concluded that chlorine is
short-lived in seawater and that the major components in chlorinated seawater
would be oxidants of chlorine and bromine as well as organic and inorganic
halogenated amines. Thus, the "free chlorine residual" would be converted
to "combined residual chlorines". Other studies conducted by Carpenter et.
al. (9) and Hostgaard-Jensen et.al. (33) resulted in similar findings.
Carpenter's work supported much of Johnson's findings regarding the presence
of a large amount of bromlnated species in chlorinated seawaters.
Hostgaard-Jensen et.al. (33) also concluded that chlorine decay could
occur as a result of reactions with organic material and other chemical spe-
cies present in seawater; thus, the chlorine could be reduced to organic ion-
ic and/or chlorides. They then studied the decay of chlorine residuals in
cooling water upon discharge into water bodies. In these studies they found
that laboratory experiments predicted chlorine residual concentrations approx-
imately twice as high as those actually measured in field tests. In field
tests they found that the discharge water contained 1.0 mg/1 residual chlor-
ine and within 100 meters of the outfall the residual chlorine concentration
was between 0.05 to 0.10 mg/1.
In his study of five California power plants Hergott et al. (12) found
that if a free chlorine residual concentration of 0.50 mg/1 (ppm) was main-
tained at the condenser tailpipes, the maximum total oxidant residual at the
outfall would be 0.16 mg C^/l which would decrease to approximately 0.09
mg C12/1 within 50 feet (15.3 m).
The reduction in chlorine concentration from the cooling water outfall
to some distance away from the outfall is due to two factors: chlorine decay
by chemical reactions and effluent dilution. Both of these factors are of
Importance in analyzing the toxicity of chlorinated cooling water effluent.
By comparing the chlorine residual concentrations in the outfall of the
power plant cooling systems discussed above with the toxicity information pre-
sent 1n the Toxic Level Section, it can be seen that the chlorine levels in
5-19
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cooling water discharges can be toxic to certain marine organisms. The de-
gree of toxicity is, however, dependent upon the organism exposed and the
exposure time. The reaction of soft organisms, slime and sponges, to chlorine
is in some respects quite different than that of hard-shelled organisms, such
as mussels and barnacles. Some organisms, which are identified in Tables 12
and 13, show great tolerances to high levels of chlorine for short exposure
times while they are quite intolerant to low level concentrations for long
exposure times. Other organisms adapt readily to low level concentrations
and long exposure times but respond violently to high levels for short ex-
posure time. It 1s for this reason that blofouling control techniques in-
corporate continuous low level chlorlnatlon 1n conjunction with intermittent
high level chlorination.
Qualitative Analysis of the Toxicity and Measurement of Pollutants Formed
In Chlorinated Seawater
This section will discuss the information previously presented and points
out areas where data gaps exist. A discussion of the amperometric titration
method and how well it can be used to measure oxidants from chlorination is
also Included.
As pointed out by Johnson (11) the major problem that confronts the re-
search in determining the toxicity of compounds found in chlorinated seawater
1s the Identification of chemical species that are actually present. Accord-
Ing to Johnson the major species of concern are: bromine, chloramines, and
bromamines; each of these components have a high probability of causing toxic
effects to marine life. Sugam (8) in his discussion of the various species
of chlorine produced oxidants supported Johnson's position. They both con-
cluded that chlorine was short-lived in seawater, and that in the absence of
amino-nitrogens in seawater (pH8) the majority of the species measured as
"residual chlorine" would be bromine. When ami no-nitrogen is present the
formation of organic and inorganic halo-amines competes with the formation
of bromine. The formation of halo-amines is favored kinetically by high pH,
low salinity, high ami no-nitrogen levels and high ami no-nitrogen to chlorine
ratios. Carpenter et.al. (9) in their study of halogen chemistry concluded,
as did Sugam and Johnson, that chlorine reacts with bromide to form bromine
5-20
-------
species and chloride ions. They further concluded that the halo-organics
formed by chlorinating seawater are likely to be brominated species.
Currently, studies by the University of Washington, the University of
North Carolina, and Battelle Pacific Northwest are being conducted to iden-
tigy the various species formed by the chlorination of seawater. Prelimi-
nary findings indicate that the chemistry involved is quite complex and that
the species formed are highly dependent upon the characteristics of the in-
take water (including water quality and salinity, season of the year, and
residence time in the cooling circuit).
The results of these studies and toxicity testing of the various spe-
cies formed will be necessary in order to formulate any meaningful data on
the toxic effects to marine life. If, however, assuming that the informa-
tion supplied by Sugam, Johnson, and Carpenter is indicative of the chemical
species found in chlorinated seawater and comparing this information with
current testing techniques, a number of interesting anomalies occur. Sugam
(25), in more recent studies, found that these brominated species plus others
cause interferences in amperometric titration readings, and that bromamines
cannot be clearly separated from free chlorine or bromine. Because the am-
perometric method measures bromine and iodine residuals in addition to chlor-
ine residuals, Hergott et al, (1) referred to the results of amperometric ti-
tration tests conducted on chlorinated seawater as "oxidant residuals" rather
than "chlorine residuals".
The amperometric titration testing method was discussed in detail in
Section 4,0. It is found that the amperometric titration method appears to
be adequate in any determinations involving toxic oxidants that may be pro-
duced by the chlorination of seawater. Although the measurement of indivi-
dual species from chlorination may not be possible, a relatively accurate
determination of the total oxidants can be made. As suggested by Johnson
(11) and discussed by Goldman et al. (31) and Ericson et al. (32), compounds
such as bromamines, chloramines and various other brominated species which
cause interferences to the method may have toxicities equal to or greater
than the chlorine itself. If these compounds are perceived as total oxi-
dant residual rather than free chlorine residual, then the amperometric
titration method may be applicable.
5-21
-------
If it becomes necessary to monitor individual components in the cooling
water discharge stream, then more advanced analytical methods will have to
be developed. Concurrent with analytical method development, studies of the
toxicity of individual as well as combined components must be undertaken.
Mattice and Zittel (28) developed a graph to show the toxicity of "resi-
dual chlorine" to marine organisms. The graph summarzied data from various
other research studies. Figure 7 presents a slightly modified version of
that graph. This graph contains estimates of both acute and chronic toxicity
thresholds. The implication of the graph 1s that 1f a dose-time combination
1s lower than the chronic toxicity threshold or to the left of the acute tox-
icity threshold no mortality is likely to occur as a result of chlorinatlon,
Mattice and Zittel developed the "threshold line" using data which were, for
the most part, 50 percent effect levels on either mortality or sublethal phy-
siological rates, and then adjusting the line to zero mortality levels. As
shown on the graph, concentrations below 0.02 mg/1 have no lethal effect re-
gardless of an increase in exposure time.
Comparing "free residual chlorine" levels developed by current practices
1n power plant cooling circuits with the toxicity threshold shown in Figure 7
1t can be seen that the target levels (0.25 - 1.0 mg/1) developed within the
cooling circuit will produce "acute toxic effects" on marine life for exposure
/
times greater than 2 1/2 minutes (at lower concentration limits), and less
than one minute (at the upper concentration limit). !
As has already been discussed,if rather than measuring "chlorine resi-
dual" the amperometric titration method measure "oxidant residual" and if the
effluent stream is shown to be toxic then current standards should be revised
to place a limit on the "oxidant residual" rather than "chlorine residual"
1n the effluent stream.
5-22
-------
en
i
no
OJ
10.
I 1
10
I
at
c
i-
o
0,01-
0.001
10
-1
I I
II I~T pi i I i ill | ii
n 1 * 9 1
10° 101 ID*1 lO3
Duration of Exposure (min)
Figure 7. Toxicity of chlorine to marine organisms (22)
10'
-------
REFERENCES
1. Hergott, S., et.al., Power Plant Cooling Water Chlorination in Northern
California, University of California, Berkeley, UCB/SERL No. 77-3,
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9. Carpenter, J.H. and D.L. Macalay, Chemistry of Halogens in Seawater.
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The Environmental Impact of Water Chlorination. Oak Ridge, Tennessee,
October 22-24, 1975.
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6-1
-------
16. Marks, H.C. and Glass, J.R., "A New Method of Determining Residual
Chlorine", JAWWA Vol. 34, 1942, pp. 1227-1290.
17. American Public Health Association, Standard Methods for the Examina-
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Oxldants 1n Chlorinated Sea Water", Environ. Sen. and Tech., 11(10)
pp. 992-994, Oct. 1972.
20 White, G.C., Handbook of Chlorinatlon, Van Nostrand Reinhold Co., N.Y.
1972, pp. 264:
21. Bradbury, J.H. and A.N. Hambly, "An Investigation of Errors in the
Amperometric and Starch Indicator Methods for the Titration of Milli-
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Chlorinatlon. Journal of Water Pollution Control Federation, Vol. 48,
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Aquatic Life. Battelle Pacific N.W. Laboratories, U.S. Atomic Energy
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Effects of Chlorinatlon at Coastal Power Plants, Water Chlorination
Environmental Impact and Health Effects, Vol. 2, editor R.L. Jolley
et.al., Ann Arbor Science, 1978,
6-2
-------
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7-1
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7-2
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7-3
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7-4
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7-5
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