Phase two

The initial experiments with NTA demonstrated a number

of problems with the artificial stream facility. No
attempt was made to rectify most of these during the NTA
work so that all personnel time could be devoted to data
acquisition. The next use planned for the stream facility
was a study to determine the fate of low levels of mercury
introduced as mercuric ion into the channels and to deter-
mine biological effects resulting from the mercury. A
great deal of preparation was necessary before this work
could be started.

When the NTA study was over, all sand was removed from

the channels and the plastic lining, which was already
beginning to deteriorate, was removed. Based on the
recommendations of experts familiar with reservoir and
irrigation channel linings, a 20 mil black PVC (polyvinyl
chloride) film was selected for lining material. This

plastic was purchased so that each channel lining would be

a single piece. After the streams and pools were covered,

a two inch layer of new sand was placed on the bottoms of the
channels. To cut down on the input of organic material into
channels 1 and 6 (insects, mice, spiders and millepedes were
often found in these channels), a PVC lined moat about six
inches deep was constructed on each side of the channel

system (Figure 4). The moat next to channel one also served
to eliminate the extra heat input to the outside wall of
channel one by direct sunlight. The areas between the channel
pairs were partitioned and flooded to somewhat alleviate
excessive heating of channel three and channel five walls

and, secondarily, provide additional. experimental chambers and
conditioning areas. These are also visible in Figure 4.

Continuous recording water quality monitors were installed

at the head and tail ends_of the channels. These units,
Schneider Instrument Company RM25 Robot Monitors, have
provisions for recording dissolved oxygen, pH, conductivity,
temperature and solar radiation input. A switching system
was designed so that each channel is monitored for ten
minutes each hour. The submersible pumps and building
housing the monitor at the head end of the channels are shown
in Figure 5.

When stream operation was. first begun as described in Phase
one of this report, a number of attempts were. made to intro-
duce fish, especially mosquitofish (Gambusia affinis) into the
channels. No amount of conditioning was sufficient to allow
these animals to survive for more than several days. Twenty
yards from the ends of the channels in the effluent stream,
however, there appeared a breeding mosquitofish population

12


Figure 1. View of upper portion of stream channels, head pools, and water input system.


91

Figure 6,

Water treatment facility consisting of limestone filled tubes.


Section

Ir

IIr

Iv

vI

CONTENTS

Conclusions
Recommendations
Introduction
Analytical Methods
Experimental Results
Phase One -
Phase Two -

References

Page

12

25


Figure 4. View of PVC covered channels showing moat at extreme
left and pump system feeding water quality monitors.

13


Uptake Of Mercury By

Granulated Rubber

100

so |
|
c \
2 \
3 |
2 60 J, ® With Mixing
° | Without Mixing
£ \
|
a |
£ 40] |
=
bd \
§ |
o
= \
\
e% 204 1
\
\
\
\
\
0 ==. r ——-—_.
t) 1 2 3 4
Hours

Figure 8, Results of rubber uptake.

19


resulting from animals that had escaped. Even these could
not survive when transferred back to the channels. The
major differences in water quality between the effluent
stream where the fish survived and the channel water were
pH and total hardness. The water leaving the tail pools
passes with much turbulence through a poured concrete
channel.

A water treatment system was installed at the head pools to
make the water entering the channels more like what is found
in natural streams in this area. The cost of a single large
system to treat all the water, the most desirable approach,
was too high and six separate systems were constructed. Each
consists of three PVC sewer pipes filled with limestone chips
through which the water must: pass before entering the head
pools (Figure 6). We have found that the limestone must be
changed at least monthly to maintain a relatively constant
water quality. Fish survive with no difficulty in the treated
water.

After the installation of the water treatment facility, the
water was turned on, adjusted to a flow of 25 gallons per
minute, and the streams allowed to seed naturally- Four
hundred mosquitofish were introduced into each channel.

A major source of variability in the NTA-phosphate data was
due to erratic functioning of the chemical feed system. The
pulsed solenoid valve technique, which has been used so suc-
cessfully in laboratory studies at the Southeast Water Labor-
atory, behaved poorly in the field because of the highly
alkaline phosphate solutions and the extreme temperature fluc-
tuations. For the mercury study, a four channel peristaltic
tubing pump was obtained (Figure 7) and procedures established
whereby the pump is recalibrated daily. The mercury solutions
are input directly into the channels at a depth selected from
the results of a series of dye dispersal studies.

Because of the sensitive position of the Savannah River Plant
with respect to environmental contamination, there was some
concern over our proposed experiments which would result in
releases of mercury to the environment. A method was sought
whereby mercury in water from the channels would be removed
before the water was released into natural streams. A number
of approaches were suggested but the most feasible appeared

to be a system that would utilize the ability of vulcanized
rubber to tightly bind mercury. This property of rubber was
pointed out by Mr. Edwin R. Russell of the Savannah River Lab=
oratory (SRL) and, indeed, forms the basis for a patent appli-
cation by Mr- Russell and others from SRL.

15


Figure 3, NTA and phosphate chemical feed system,

10


SECTION IT

RECOMMENDATIONS

1. The interaction of NTA with mercury and other
metals needs intensive investigation before NTA is
released in large quantities to the environment.
Especially needed are studies to determine NTA effects
on heavy metal movement between components of aquatic
ecosystems and how these are influenced by other
additions (thermal, organic, chemical, etc.) to the
aquatic habitat.

2. The use of vulcanized rubber scrap as a mercury
removal agent should be futher investigated. De-
contamination of problem areas in the environment
may be feasible.


SECTION VI

REFERENCES

Federal Water Pollution Control Administration, FWPCA
Methods for Chemical Analysis of Water and Wastes, U. S.
Dep. Interior, FWPCA, Cincinnati, Ohio, 280 p. (November
1969).

Kerr, P. C., D. F. Paris, and D. L. Brockway, The Inter~
relation of Carbon and Phosphorus in Regulating H Hetero-
tropic and Autotrophic Populations in Aquatic Ecosystems,
U. S. Dep. Interior, Fed. Water Quality Admin., Water
Pollution Control Research Series 16050 FGS, U. S. Govt.

Printing Office, Washington, D. D., 53 p. (July 1970).

Southeast Water Laboratory, Environmental Fate of NTA,
Environmental Protection Agency, Water Quality Office,
Project 16050 GJB, U. S. Govt. Printing Office, Washing-
ton, D. C., 50 p. (May, 1971).

Standard Methods for the Examination of Water and Waste-
water, 12th Ed., Am. Public Health Assoc., Inc., N. Y.,
N. ¥. (1965).

Thompson, J. E., and J. R. Duthie, "The Biodegradability
and Treatability of NTA," J. Water Pollution Control
Federation 40(2): 306-319 (1969).

Uthe, J. F., F. A. J. Armstrong, and M. P. Stainton.
1970. "Mercury determination in fish samples by wet
digestion and flameless atomic absorption spectro-
photometry." J. Fish. Res. Bd. Canada 27: 805-811.

25


Plastic strips suspended in streams,

Figure 11,

22


No.

1

Well Water Analysis

TABLES

Page


10.

ll.

12.

FIGURES

view of upper portion of stream channels,
head pools, and water input system

Weirs by which flows into the channels are
measured

NTA and phosphate chemical feed system
View of PVC covered channels showing moat
at extreme left and pump system feeding

water quality monitors

Pumping system and water quality monitor at
head end of streams

Water treatment facility consisting of
limestone filled tubes

Mercury input feed system with four channel
peristaltic pump

Results of rubber uptake

Rubber beds in tail pools for removal of
mercury from artificial stream water

The uptake of mercury from a mercuric
chloride solution by a polyvinyl chloride
film

Plastic strips suspended in streams

Influence of NTA on mercury uptake by
mosquitofish, Gambusia affinis

iv

Page

10

13

14

16

17

19

20

21

22

23


into air tight vials, sealed and refrigerated. Bacterial
samples were taken in acid washed sterile containers, acid-
ified immediately and refrigerated until analyzed. Inor-
ganic carbon samples were filtered through 0.22 micron filters
into air tight vials, sealed and refrigerated. Bacterial
samples were taken in sterile dilution bottles and pour plates
made within 15 minutes. The results of all chemical analyses
and bacterial counts were punched on computer cards and
computer programs written for data analysis by Southeast
Water Laboratory personnel. A summary of results is given

in the final report of Project 16050 GJB, Environmental

Fate of NTA, (SEW, 1971). The variability of the data was
such that tests for upstream-down-stream changes, and differ-
ences between treatments were very insensitive. No signif-
cant removal of NTA in any of the channels was detected.
There were significant differences between treatments with
respect to the bacterial counts, Na3 PO4>Na3P04, + NTA>NTA
controls, as determined by a Duncan's Multiple Range Test.
This ranking corresponds to the average pH of the water in
the channels, which was greatly influenced by the additions
of the NTA and Na3 PO4.

During the period of this study, several general observa-
tions were made that could not be considered quantitatively
due to the lack of available personnel. At the start of the
chemical input, there were extensive algal mats in all the
head pools. The character of the mats other than the con-
trols changed in time, apparently as a result of the chemical
input. The mats in pools receiving NTA, either alone or with
phosphate, became a brighter green, while the mat in the pool
receiving only Naz,P0, was destroyed and transported over

the weirs into the channels. The mats in the remaining pools
were manually destroyed and allowed to pass downstream to
maintain all channel systems in a similar condition. Micro-
scopic examination of the mats shortly before this time
showed no gross differences in qualitative species structure.
Mats reformed quickly in the control pools, more slowly in
all the pools receiving NTA, and did not form at all in the
pool receiving only Na3P0,-

These observations suggest an effect of NTA on the biological

communities, even though the results of chemical analyses did

not indicate a significant removal, hence utilization, of this
compound. Also indicated is some type of interaction between

NTA and trisodium phosphate.

ll


SECTION I

CONCLUSIONS

1. There is no detectable degradation of NTA, either
added alone or with trisodium phosphate, during a two
hour period in artificial stream systems.

2. Biological differences between treatments, as
determined by visual observations and bacterial
counts, may have been the result of treatment -
induced pH changes in these soft water systems.

3. Granulated vulcanized rubber, a waste product
of commercial tire recapping operations, provides

a convenient and economical method of removing in-
organic mercury from water. Uptake is not affected
by NTA.

4. NTA does affect the uptake of mercury from water
by mosquitofish, Gambusia affinis.


LT

Figure 7.

Mercury input

feed system with four channel peristaltic pump.


Ecological Research Series

NTA and Mercury in

Artificial Stream Systems

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Office of Research and Development

U.S. Environmental Protection Agency

Washington, D.C. 20460


SECTION IV
ANALYTICAL METHODS

Analyses for NTA, total organic carbon, total inorganic
carbon, orthophosphate and nitrate were carried out by
personnel of the Southeast Water Laboratory on samples
prepared at the stream site and transported on ice to
Athens, Georgia.

NTA was determined by the Zinc-Zincon semi-automatic
procedure for the Technicon Autoanalyzer as described

by Thompson and Duthie (1968). The minimum detectable
concentration of this method is 0.2 mg/liter as Na3NTA.
A hydrogen form cation exchange resin was used to remove
cations that might have interferred.

Total organic carbon was determined from acidified
nitrogen-purged samples on a Beckman Model 915 Total
Carbon Analyzer coupled to a Beckman Model 215A
Infrared Analyzer.

Total inorganic carbon was determined by the procedure
described by Kerr et al. (1970) utilizing a Varian
Aerograph Gas Analyzer.

Orthophosphate and nitrate concentrations were determined
on a Technicon Autoanalyzer according to procedures
described in FWCPA Methods for Chemical Analysis of
Water and Wastes, (1969). ~

Suspended bacteria were counted by serial dilution pour
plates made with tryptone glucose extract agar.

All pH measurements were made with an Orion Specific
Ion Meter and a Corning combination electrode.

Mercury determinations were made on a Coleman MAS 50 Analyzer
modified by the addition of a digital read-out system. Fish
were digested using the procedure described by Uthe et al.
(1970). Analytical instructions provided with the Coleman
Analyzer were followed.


SECTION III
INTRODUCTION

Phosphates have been implicated in the increased rate

of eutrophication in some streams and lakes. Since a

great portion of the phosphates introduced by man into

the environment result from the use of detergents, a

great effort has been made to find phosphate substi-

tutes. One compound that is now in use in some countries

is the trisodium salt of nitrilotriacetic acid, usually
referred to as NTA. This compound was voluntarily

removed by manufacturers from detergents in the United States
at the request of the Surgeon-General. The request was

made because of the many unknown factors involved in the
release of great quantities of a relatively unknown compound
into the environment. Two areas of general concern were

the possible production of carcinogenic products under certain
conditions of NTA degradation, and the interaction of NTA,

a well known chelating agent, with heavy metals in the
environment.

The work described in this report consists of two phases.

The first phase, an attempt to determine the fate of NTA
introduced into artificial stream systems, was carried

out in conjunction with personnel from the Environmental
Protection Agency's National Pollutants Fate Research Program,
Southeast Water Laboratory, Athens, Georgia. The second
Phase involved modifications of the stream facility

and preliminary experiments with mercury and mercury-NTA
interactions in preparation for a long term mercury study.

The mercury work is presently underway.


Further analysis of the data showed significant negative
correlations between body weight and mercury concentration
in the NTA +Hg treatments but not in the Hg treatments
alone.

Several tests were made which showed the NTA in no way
interferes with the mercury analyses as performed. Since
it appears that NTA may yet become a major detergent
constituent in this country, further work is needed on
the interaction of this compound with mercury and other
heavy metals.

24


ppm Wet Weight (K + 2SE)

Of Mosquitofish ,

Body Burden

3.5

3.0

2.5

2.0

1.5

1.0

0.5

Mercury Uptake By Mosquitofish

As_ Influenced By NTA
.
:
:
'
:
q ‘
:
:
:
‘
:
:
:
:
.
:
:
:
L. ‘
°
. .
: :
‘ :
: :
: :
: :
: :
: :
: :
: :
: :
- : :
: :
:
:
:
H :
: :
: .
: :
:
‘
:
5 : @ NTA (10 mg/t)
:
. O Noe NTA
.
:
q
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.
:
.
1 1 1
t+) 0.05 0.10 0.20
mg/i Hgtt+ In Water
Figure 12. Influence of NTA on mercury uptake by mosquitofish,

Gambusia affinis.

23


ACKNOWLEDGMENTS

The support of the staff of the National Pollutants Fate Research
Program, Southeast Environmental Research Laboratory, is acknowledged
with sincere thanks. Special recognition is due Mr. Bruce C,

Ferguson of this group who coordinated the effort between the Savannah
River Ecology Laboratory and the Southeast Environmental Research
Laboratory,

vi


Figure 5, Pumping system and water quality monitor at head end
of streams,

14


0z

Figure 9.

Rubber beds in tail pools for removal of mercury from artificial stream water.


ABSTRACT

Studies were conducted in six artificial stream channels to determine
the fate of NIA (nitrilotriacetic acid, trisodium salt) added with
and without sodium phosphate to these systems, In the two hour
period required for a given water mass to traverse the channels,
there was no appreciable removal of NTA or phosphate, even after a
one month period of continuous input. Visible biological differences
were noted between the various treatments, These differences may
have been a result of pH alteration caused by the addition of the
trisodium phosphate and NTA,

In anticipation of a long term program involving the fate of mercury
and possible mercury-NTA interactions, several modifications were
incorporated into the artificial stream system. Based on the results
of laboratory studies, a mercury removal system utilizing shredded
rubber tires as obtained from commercial tire recapping firms, was
constructed, Laboratory studies indicated that NTA did not influence
the uptake of mercuric ion by the rubber. The presence of NTA did
alter the uptake pattern and final concentration by mosquitofish,
Gambusia affinis.

This report. was submitted in fulfillment of Grant 16050 GQQ, Program

Element 1BA023, to the University of Georgia-under the sponsorship of
the Environmental Protection Agency,

ii


Figure 2. Weirs by which flows into the channels are measured,


introduced on several occasions into the head pools and
channels for seeding purposes. Unsuccessful attempts
were made to introduce fish (Gambusia affinis and
Semotilus atromaculatus) into the channels. The last
seeding was in mid September when 10 gallons of material
were placed in each head pool, and the water flow reduced
for a period of 24 hours to allow organisms to settle.
The channels were then not disturbed for one month

except for periodic adjustment of the flows. After

this period, an intensive diel study was conducted

to establish pre-dosing conditions and optimum sampling
times. At that time large floating mats (algae and
bacteria) had formed in all the head pools. Filamentous
growth was visible on the walls and bottoms of both pools
and channels. The growth was greatest near the input
ends of the channels. The channels appeared to be very
similar.

A chemical feed system was installed near the head pools to
provide a continuous input of NTA and phosphate solutions.
This system (Figure 3) consisted of four 54 gallon polyethy-
lene-lined drums, air lift pumps which maintained a constant
liquid level in four polyethylene bottles located on the
drums, and four solenoid valves which were electrically
pulsed to maintain the desired input rate. Flows from the
solenoid valves entered the head pools near where the water
was input so as to provide instant mixing.

Of the six channels, two were maintained as controls (1 and

4, looking from tail to head and counting left to right),

two (3 and 5) received inputs of NTA and trisodium phosphate
to provide 10 mg/liter of each compound, one (2) received NTA
alone, and the last (6) received Na,PO, alone, again to pro-
vide concentrations of 10 mg/liter. The chemical feed system
was started on October 22, 1970. A continuous input was main-
tained until November 23, 1970 when subfreezing temperatures
caused the feed system to stop and the experiment was termin-
ated.

During the period of phosphate-NTA input, water samples were
taken at 6 am and 2 pm daily from both ends of each channel.
Temperature and pH were determined in situ. Water samples
were fixed at the streams for titrating for dissolved oxygen.
A single 150 ml water sample was taken for NTA, phosphate, and
nitrate determinations. This water was filtered through a
washed 0.45 micron sterile membrane filter into an acid rinsed
sterile container and immediately refrigerated. Total organic
carbon samples were taken in acid washed sterile containers,
acidified immediately and refrigerated until analyzed. In-
organic carbon samples were filtered through 0.22 micron filters


EPA-660/3-73-025
February 1974

NTA AND MERCURY IN ARTIFICIAL STREAM SYSTEMS

By

Henry J. Kania and Robert J. Beyers
University of Georgia
Athens, Georgia

Project 16050 GQQ
Program Element 1BA023

Project Officer

Dr. Walter M, Sanders III
Southeast Environmental Research Laboratory
Athens, Georgia 30601

Prepared for

OFFICE OF RESEARCH AND DEVELOPMENT
U. S, ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D. C. 20460


Granulated vulcanized rubber is available as a waste product
resulting from commercial tire recapping operations. We

tested rubber samples obtained locally for mercury uptake and,
while. results were somewhat influenced by the source of. the
material and the amount of pre-soaking in water, -found very
good removal of mercuric ions from low aqueous concentrations
in all cases. Since we were interested in removing mercury
from our stream water, experiments were carried out at room
temperature and a slightly acid pH. Figure 8 .shows a typical
result. In this particular case, 200 mls. of pre-soaked (6
weeks) granulated rubber was added, both with and without
continuous mixing, to 800 mls of a mercuric chloride solution
containing 1 mg Hgt+/liter. 10 mg/liter NTA did not affect

the uptake of the mercury.by the rubber. Based on these labor-
atory studies, the tail pools at the ends of the channels

were modified into mercury recovery facilities with the under-
standing that. the contaminated rubber would be buried as radio-
‘active waste at the end of the experiments. Figure 9 shows

two systems already filled with the rubber granules.

The ability of mercury to adsorb to many surfaces prompted a
study to determine uptake by the PVC stream lining. Isotope’
tracer techniques were used. Small measured pieces of PVC
film were submersed in one liter of 1 mg/liter Hg++ solution
spiked with Hg 203. Pieces were removed periodically, rinsed
with distilled water, counted for activity, and total attached
mercury calculated. The mercury solution was made up using
artificial stream water. Results are summarized in Figure 10.
The PVC appears to saturate at about 3250 micrograms of mercury
per square meter of exposed surface. To measure actual up-
take in the streams, 80 PVC. strips were suspended in each of
the channels to be removed periodically for Hg analysis
(Figure 11). These same strips are to be used for biomass
data to estimate growth on the channel walls.

At a time when it still seemed likely NTA would be immediately
introduced on a large scale into detergents, laboratory studies
were begun to consider some possible interactions between NTA
and mercury. Mosquitofish were exposed to-sublethal levels

of mercuric ion (0.05, 0.10, 0.20 mgs/liter) both in the
presence and absence of 10 mg/liter NTA. Results are pre-
sented in Figure 12. After 18 hours of exposure, fish were
digested and analyzed. for total mercury. Body concentrations
of fish exposed to mercury and NTA were independent of the
mercury content of the water while the concentrations of those
exposed to mercury alone was significantly correlated (r=
0.72, p€O.01) to the mercury concentration.

18


RESEARCH REPORTING SERIES

Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:

1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research

4. Environmental Monitoring

5. Socioeconomic Environmental Studies

This report has been assigned to the ECOLOGICAL
RESEARCH series. This series describes research
on the effects of pollution on humans, plant and
animal species, and materials. Problems are
assessed for their long- and short-term
influences. Investigations include formaticn,
transport, and pathway studies to determine the
fate of pollutants and their effects. This work
provides the technical basis for setting standards
to minimize undesirable changes in living
organisms in the aquatic, terrestrial and
atmospheric environments.

EPA REVIEW NOTICE

This report has been reviewed by the Office of Research and
Development, EPA, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policies of the Environmental Protection Agency,
nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price 70 cents


SELECTED WATER 4, Report No.) 2. 3. Accession No.
RESOURCES ABSTRACTS Ww
INPUT TRANSACTION FORM
4. Title S. Renort Dave

NTA AND MERCURY IN ARTIFICIAL STREAM SYSTEMS 6

8. Performivg Organization

7. Author(s) Report No.

Kania, Henry J., and Beyers, Robert J. 10. Project Ne.

9. Organization
LL, ttomrenes! Grant No.

Institute of Ecology
The University of Georgia 16050 GQQ
13. 7; f, and
Athens, Georgia Penssleas*
12, Sponsoring Organization Environmental Protection Agency Final Report

15, Supplementary Notes
Environmental Protection Agency report number, EPA~660/3~-73-025, February 1974.

16. Abstract
Studies were conducted in six artificial stream channels to determine the fate of NTA

(nitrilotriacetic acid, trisodium salt) added with and without sodium phosphate to these|
systems, In the two hour period required for a given water mass to traverse the
channels, there was no appreciable amount of NTA ‘or phosphate, even after a one month
period of continuous input. Visible biological differences were noted between the
various treatments, These differences may have been a result of pH alteration caused
by the addition of the trisodium phosphate and NTA.

In anticipation of a long term program involving the fate of mercury and possible
mercury-NTA interactions, several modifications were incorporated into the artificial
stream system. Based on the results of laboratory studies, a mercury removal system
utilizing shredded rubber tires as obtained from commercial tire recapping firms, was
constructed, Laboratory studies indicated that NIA did not influence the uptake of
mercuric ion by the rubber, The presence of NTA did alter the uptake pattern and
final concentration by mosquitofish, Gambusia affinis. (Kania - University of Georgia)

17a. Descriptors
*Heavy metals, Phosphates, Degradation, Environmental Effects,

*Detergents

I7b. Identifies
enuners  sitrolotriacetic acid, *NTA, Mercury, *Artificial Stream Channels

7c. COWRR Field & Group $5B

18. Availabilit 19, Security C's. | 21. Wo of Send To:
ia (Report) Pages
; Waren nesourc
20. Securizy Class. | 22. Price U's DEPARTMENT OF THE INTERIOR NATION CENTER
(Page) WASHINGTON, D.C, 20240
Gbstactor Henry J, Kania | tnstirution University of Georgia

WREIC 192 (REY JUNE F871

“#e US. GOVERNMENT PRINTING OFFICE: 1874 546~319/380



TZ

Mercury/ sq. meter

Micrograms

Mercury

Uptake By PVC Film

40004
- Qe arr
30004 ueerre
_-@-
77
-
eae
2000 4 ,
¢
¢
va
¢
¢
4
1000 - 7
®
f
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oO T — 7 + : : : ;
° 2 é 10 14 18 22 26
Exposure Time in Hours

Figure 10.

The uptake of mercury from a mercuric chloride solution by a polyvinyl chloride film.


SECTION V

EXPERIMENTAL RESULTS

Phase one

The artificial stream facility used in this study was
constructed the summer of 1970 at the Atomic Energy
Commission's Savannah River Plant. The particular
site was chosen because of the availability of an
adequate water supply and a level concrete platform
of sufficient size. The facility consists of six
concrete block channels 300 feet long, 2 feet wide
and one foot deep with pools, 10 feet long, five feet
wide and two feet deep, located at both ends. Figure l
shows the six head pools, flow adjust valves, V-notch
weirs, chemical feed systems and initial 30 feet of
the stream channels. The system is arranged so that
water can be input either into the pools or directly
into the channels.

For this phase of the work, the entire system was

lined with 11 mil transparent polyethylene sheeting,

a covering selected because it was immediately available.
Washed quartz builder's sand was placed in the channels to
a uniform depth of 2 inches.

Water supplied from a deep well was input to the head
pools and the valves adjusted to provide 25 gallons
per minute into each channel as measured by weirs
(Figure 2). The quality of the well water has been
periodically monitored by E. I. duPont personnel since
1952 and the measured parameters vary little in time.
A typical analysis is given in Table 1. Adjustable
plates at the ends of the channels were set to main-
tain a water depth of eight inches. With this depth
and an input of 25 gallons per minute, retention times
averaged two hours in the channels and thirty minutes
in the pools.

Water flow throught the channels was started in late
August of 1970. Material collected from local ponds
and streams originating from artesian outflows from the
same aquifer supplying the artificial streams, was


TABLE I

WELL WATER ANALYSIS

Total Organic Carbon 3.2 mg/liter
Inorganic Carbon as CO2 24.75 mg/liter
Nitrate .190 mg/liter
Orthophosphate -0015 mg/liter
Hardness Ca CO3 5.0 mg/liter
Dissolved Oxygen 9.5 mg/liter
Temperature 21.0°C

pH 4.7