oa
Vinyl Chloride
in Atmosphere

42

x2

Viny! Chloride
INPUT == ——P OUTPUT
in Water

Figure 4. Best estimate model of vinyl chloride in the
aquatic environment.

10


VINYL CHLORIDE x 103, mg/I

Figure 20.

Vinyl Chloride in Hypolimnion
Water

—-—-—-— Vinyl Chloride in Benthic
Organisms

——--— Vinyl Chloride in Filter
Feeding Organisms

(Hypolimnion)
2.86 oe =—=s
a
/
/
/
/
1
/
Ul
/
1.43 + | i”
I
I
I
I
I
I
i]
L
-
oF 50 100
TIME, days

Stratified lake model's response to pulse input
of vinyl chloride to sediments.

31


Vinyl Chloride in Filter Feeding
Organisms (Hypolimnion)

-<-— Vinyl Chloride in Benthic
Organisms

—-——--—— Vinyl Chloride in Predator
Organisms

-————---—— Vinyl Chloride in Omnivorous
Organisms

2.20

1.10

VINYL CHLORIDE x 10°, mg/!

Figure 16. Stratified Lake model's response to pulse input
of vinyl chloride to epilimnion water.

27


The vessel was filled to the top with water and 20 ml of
vinyl chloride was added. The filled vessel was placed in a
constant temperature bath (+ 29°C) and removed at recorded
intervals for analysise The concentration of vinyl chloride
at each time interval was determined by comparison of glc
peak heights using a vinyl chloride-carbon tetrachloride
standard solutions Experimental error was determined to be
+ 10%.

Gle analysis was carried out on a Tracor Microtech 220
Gas Chromatograph fitted with a 3 m x 063 cm column packed
with 064% Carbowax 1500 on Carbopack; injection, column, and
detector temperatures were 210°c, 40°C, and 210°C,
respectivelye

RESULTS AND DISCUSSION

pH Studies

In reaction mixtures at pH 3-0 (HCL), 7e0, and 11.0
(NaOH) at 85°C, no reaction could be detected after 27
hourse Extrapolation of data, assuming hydrolysis,
elimination, addition, or substitution mechanisms, indicates
that these reactions would have half-lives on the order of
yearse

Literature information was used to estimate half-lives
for several possible reactions of vinyl chloride under
environmental reaction conditions (Table 2). The estimated
half-lives were in good agreement with our experimental
data. In view of these half-lives; any contribution to the
disappearance of vinyl chloride by chemical degradation via
these pathways normally would not be significant since other
processes are faster.

in environments like municipal water chlorination
facilities, however, high concentrations of chlorine would
existe Based on the reactivity of carbon-carbon double

bonds with chlorine and hypohalous acid, under such
conditions vinyl chloride may be converted to more highly
chlorinated compounds.

Oxidation Studies

The reactivity of vinyl chloride with molecular oxygen
was also investigated. Experiments were carried out at 20

36


Conceptual Models of
Vinyl Chloride Interactions
in Aquatic Ecosystems

Model Structure

Mathematical Models of
Viny! Chloride Behavior

Simulation

System Analysis of
Mathematical Models

Mode! Parameters

Quantitative
Interactions

Qualitative
Interactions

Chemical, Biological, and
Physical Experiments

Mechanistic Behavior

Holistic Behavior

Figure 1.

procedurese

Results and Conclusions

Composite representation of the analysis


TECHNICAL REPORT DAT,

‘A
(Please read Instructions on the reverse before completing)

7. REPORT NO.
EPA-600/3-76-001

2

3. RECIPIENT'S ACCESSIONNO.

4. TITLE AND SUBTITLE

DYNAMIC BEHAVIOR OF VINYL CHLORIDE IN AQUATIC
ECOSYSTEMS

Is. REPORT DATE

January 1976 (Issuing Date)
6. PERFORMING ORGANIZATION CODE

17. AUTHOR(S) .
James Hill IV, Heinz P. Kollig, Doris F.

N. Lee Wolfe, and Richard G. Zepp

Paris

ls. PERFORMING ORGANIZATION REPORT NO.

I9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Research Laboratory

Office of Research and Development
U.S. Environmental Protection Agency
Athens, Georgia 30601

10. PROGRAM ELEMENT NO. 1BAQ2
ROAP O4AEM;Task 005,ROAP d3aco,
‘ask 009

11. CONTRACT/GRANT NO.

12. SPONSORING AGENCY NAME AND ADDRESS

Same as above

13, TYPE OF REPORT AND PERIOD COVERED

Task Milestone Rept. FY75
14, SPONSORING AGENCY CODE

EPA-ORD

15, SUPPLEMENTARY NOTES,

16. ABSTRACT
To evaluate the behavior of vinyl chloride

of the chemical, biological,

These transformations included oxidation,
hydrolysis, and free radical reactions;
indirect photochemical reactions;
bacterial, algal, and fungal sorption;
vinyl chloride from the aquatic environment by

best estimate and worst case models of lake and stream ecosystems were
analyzed through the use of mathematical simulation.
and physical transformations of vinyl

chloride indicated in the models were determined by laboratory experi-
mentation and extrapolation of reaction data for similar compounds.

substitution,
complexation;
microbial degradation and toxicity;
and volatilization.

to be the most significant process in its distribution.

in aquatic ecosystems,

The characteristicBb

elimination,
direct and

Loss of
volatilization appeared

n7. KEY WORDS AND DOCUMENT ANALYSIS

a. DESCRIPTORS b.IDENTIFIERS/OPE!

NENDED TERMS |c. COSATI Field/Group

Systems analysis
Vinyl chloride

Chemical degradation
Biodegradation
Aquatic environment

12a
6F
8H

18. DISTRIBUTION STATEMENT 79. SECURITY CLAS:

'S (This Report} 21. NO. OF PAGES

RELEASE TO PUBLIC UNCLASSIFIED 74
20. SECURITY CLASS (This page) 22. PRICE
UNCLASSIFIED

EPA Form 2220-1 (9-73)

64

fy U.S. GOVERNMENT PRINTING OFFICE: 1976-657-695/5363 Region No. 5-11


The high susceptibility of VCM to free radical attack in
water was demonstrated by its rapid disappearance in the
presence of hydroxy free radicals generated by photoysis of
hydrogen peroxide (Figure 24). Since PVC plant effluents
are likely to contain small amounts of peroxides, such as
peroxydisulfate (32), that are used in the polymerization
process, sunlight-induced decomposition of VOM was
considered as a possible pathway for its disappearance from
PVC plant effluent water.

However, using the same apparatus employed in the
present direct photolysis studies, Thruston (3) found that
VCM photolyzed very slowly (half-life 40 hours) in PVC plant
effluent. When exposed to sunlight, it photolyzed even
slowere Very Little reaction was detected after 25 hours of
exposures

Our natural water studies were carried out in unfiltered
waters collected from the Oconee River, a moderately
polluted river in Athens, Georgia, and from the Okefenokee
Swamp, an unpolluted water that is highly colored by
dissolved humic materials.e In both natural waters, and in
water containing 20 mg Ut ! commercial “humic acid" (a
derivative of decayed plants), no decomposition of VCM (10
mg U1!) occurred during a 20-hour irradiation periode

46


studies were conducted using 1.00 x 10°* M methylene blue as
sensitizer and 578 nm monochromatic Light. Acetone
sensitization studies employed 10% (by volume) acetone in
water and 313 nm lLlighte Filter solutions (1.0 cm thick)
were as follows: 573 nm —- 50 g cupric chloride (hydrated);
150 g anhydrous calcium chloride, and 150 g potassium
dichromate in 500 ml distilled water slightly acidified by
hydrochloric acid; 313 nm - 0.001 M potassium chromate in 3%
aqueous potassium carbonate, and 3 nm-thick Pyrex sleeve.
The actinometer for the acetone sensitized photolysis was a
solution of 0.05 M benzophenone and 0.100 M_ cis~1,3-
pentadiene in benzene (37).

RESULTS AND DISCUSSION

Direct Photolysis

The rate of direct photolysis of a pollutant is
proportional to the degree of overlap between the electronic
absorption spectrum of pollutant and the spectrum of light
source, vinyl chloride and sunlight, respectively, for the

present study. Atmospheric ozone prevents essentially all
sunlight of wavelengths below 295 nm from reaching the
earth's surfacee Vinyl chloride, in the vapor phase,

however, does not absorb above 220 nm (28), and our studies
Show that in water it does not absorb above 218 nme The
longer wavelength singlet-triplet transitions of simple
ethylene derivatives that occur at wavelengths > 295 nm are
highly forbidden and thus have extremely low extinction
coefficients (38).

The lack of overlap between vinyl chloride absorption
and sunlight radiation spectra indicates that direct
photolysis of vinyl chloride would be very slow in the
aquatic environmente To confirm this experimentally, we
exposed solutions of vinyl chloride (10 mg 17!) in pure
water to filtered (> 300 nm) Light from a mercury Lampe No
photolysis occurred over a 90-hour periode The integrated
intensity of the 300-370 nm Light in our photochemical
apparatus was found to be about eight times more intense
than midday-June sunlight (lat. 34°9N) in the same spectral
regione

44


were usede The VCM stock solution was introduced by syringe
through the hole in the screw top into flasks containing
dilute nutrient broth and bacteriae Samples for gle
analysis were removed in the same manners The Teflon liner
covering the top was sealed with cellulose tape immediately
after the syringe was removede

The side-arm tube was designed to fit the Klett-
Summerson photoelectric colorimeter in which turbidity of
the culture was measured using a blue filter (425 nm)e This
allowed growth to be monitored without opening the flasks.

Each isolated bacterial population was inoculated into
two flasks containing 1:20 nutrient brothe The saturated
VCM solution was added to one of the cultures to give a
final concentration of 20 mg VCM per lLitere The other

culture, the control, received no VCMe Each series of
cultures included a flask containing medium and VCM but no
organismse The cultures were incubated at 21°C on a

gyratory shaker under an exhaust hoode

After one week the resultant populations were
transferred to a 1:20 nutrient broth solution containing 40
mg lt 1 VCM. Weekly transfers were made for a period of five
weeks, decreasing the nutrient broth concentration and
increasing the VCM concentration until nutrient broth was
diluted 1:80 and VCM concentration was 120 mg U1. After
five weeks, bacteria for degradation studies were harvested
from the 1:80 nutrient broth containing 120 mg 1 1 VCM,
washed three times, and transferred to basal salts medium
containing 54 mg 17! VCM as the only carbon sourcee Inocula
from the same series of flasks were used to continue the
toxicity studies. The concentration of nutrient broth was
decreased to a ratio of 1 part nutrient broth to 100 parts
basal salts medium and the concentration of the vinyl
chloride was increased at each 48-hour transfer until the
VCM concentration was 900 mg l}.

Bacteria used in sorption studies were grown in 1:10
nutrient broth for 24 hours, harvested, and washed three
timese Enough bacteria were transferred to S-ml graduated
centrifuge tubes with ground glass stoppers to give
approximately 5 g dry weight of bacteria per liter of water.

Fungi from three field sites were isolated on Rose
Bengal (Difco) plates and maintained on Saboraud's medium
(Difco) slantse Inocula for fungi were suspensions prepared
by agitating 10 ml of sterile water in a plate containing
the sporulating fungie The suspension was introduced into

50


SECTION VII

PHYSICAL INTERACTIONS

The conceptual model for vinyl chloride behavior in
aquatic systems suggests that volatilization may be an
important process in determining the distribution of the
compounde A preliminary study of the stability of vinyl
chloride in water (3) indicates that the loss of vinyl
chloride from water through volatilization is relatively
rapide Gas exchange experiments were therefore undertaken
to provide data for determination of the specific rate of
volatilization of vinyl chloride from watere

The specific rate of gas exchange (K) at an interface
between water and atmosphere is a function of properties (P)
of the gas molecules (ecgey diffusivity, motecular
diameter), and the turbulence (T) in the water,

K = £(P,T) (4)

If the specific rates are determined from concentrations
measured for two gases (denoted 1 and 2) simultaneously, the
common parameter, turbulence, can be eliminated from the
functional relationship

K, £(P, ,T)
x F@,D = constant (5)
2

for constant properties Py, and P2e This ratio (equation 5)
of specific rates is not significantly affected by
temperature changes between 10°C and 30°C, by the level of
turbulence, by the direction of gas transfer, or by the
presence of dissolved solids (9). In the gas exchange
experiments, the specific rate of vinyl chloride loss was
determined relative to and concurrently with the specific

54


Mechanism |. Direct Photolysis

vem @% (vCM)*
(VCM)* —» products

Mechanism II. Photosensitized Reaction (Energy Transfer)
s 1s

1g* —»3S*

3g* + VCM -+S + 3(VCM)*

3(VCM)* —» products

Mechanism II1. Chemical Sensitization
sTM se
S* + VCM — products

Mechanism IV. Light-initiated Free Radical Decomposition
A-8 % At +B

A® + VCM — ACH2CHCI*

ACH2CHCI* + VCM — polymer

ACH2CHCI* + O2 -» ACH2CHCIO2*

ACH2CHCIO2* + VCM - polyperoxides

ACH,CHCI* + B* -» ACH2CHCIB

2 ACH2CHCI* —- ACH=CHCI + ACH2CH2CI

2 ACH2CHCI* —» (ACH2CHCI+2

Figure 23. Pathways for light induced decomposition of
vinyl chloride.

42


The worst case model was analyzed using values for ay
listed in Table 1. It should be noted that these are
extreme values and would not be expected to apply ina
typical lake or stream. The values for each of the
coefficients were chosen as described.

° a1,2 -- as discussed for best estimate modele

bd 83,2 and a11,4 -- represent the combined effects of
the hypothesized chemical and biological reaction
pathways for vinyl chloride in water. Values were
determined either by assuming that the reaction
occurred at a rate immediately below the level of
detection or by extrapolating Laboratory conditions
to their extreme analog in the aquatic environment.

© a@4.2 and a2,4 —— are the results of an approximation
for eddy current transport across a thermocline,
which was extrapolated to the hypothetical lake
morphology (7).

e 26,29 87,49 and 88,5 —~ were based upon the fraction

of the lower trophic level biomass assumed to be

assimilated per year (8).

89,69 890,79 and a9g.s -- were based on the trophic

level assumption used for a6.2: 47.4, and a8,5 and

the assumption of an evenly distributed food

preference.

810,69 810,77 and @10,8 —- were based on the trophic

level assumption used for 96,27 97,41 and a8,5 and an

evenly distributed food preference.

85,67 95,79 45,a% and 85,9 —- were based upon an

average 10-day turnover time and a population loss of

90% of ingested material averaged over a year (8 )e

° 45,4 —~ assumes an average settling rate for particu-
lates of 0.1 cm sec 4 (7) and diffusion-Limited
transport in unmixed interstitial waters with an
effective surface fraction of 0.38 for several sizes
of closely-packed spherese The diffusion coefficient
for vinyl chloride was estimated from the diffusion
coefficient for oxygen and the ratio of gas exchange
coefficients (9).

© a4,s -~ assumes diffusion limited transport and no
scouring of sedimentse

The sorption of vinyl chloride onto particulates was
assumed to be reversible and very fast so that an
equilibrium with a K = 10 (see Section VI) was maintained.
The concentration of organic particulates was taken as
constant (jieees input = output) at 1.66 mg 17! (7).

14


Vinyl Chloride in Eplimnion
Water

———-— Vinyl Chloride in Atmosphere

16.9 T
7
7
y
= 7
2 _/
~ 7
2° 7
x vy
a Y
= 8.43 7 4
= 8.
S a
= 7
Oo ¢
= 7
2 oo
> Y
7
7
7
a
ole t
0 50 100
TIME, days

Figure 21. Stratified lake model's response to pulse input
of vinyl chloride to sedimentse

32


426

436

44.

456

Payne, We Je and Ve Ee Feisale Appl. Microbiol.
11:339-344, 1963.

Byington, Ke He and Ke Ce Leibmane Mole Pharmacol.
103): 247-254, 19652 Ceo As 64:11457e, 1966.

Dreisback, Re Re Physical Properties of Chemical
Compoundse Advances in Chemistry Series, Numbers 15,
22, and 29. Washington; De Ce, American Chemical
Society, 1955-1961. 407p.

Weast, Re Ceo (ed)e Handbook of Chemistry and Physicse
Cleveland, Ohio, Chemical Rubber Coe, 1971-2 pe F173-
F177.

63


ABSTRACT

To evaluate the behavior of vinyl chloride in aquatic
ecosystems, best estimate and worst case models of lake and
stream ecosystems were analyzed through the use of
mathematical simulation. The characteristics of the
chemical, biological, and physical transformations of vinyt
chloride indicated in the models were determined by
laboratory experimentation and extrapolation of reaction
data for similar compounds. These transformations included
oxidation, substitution, elimination, hydrolysis, and free
radical reactions; complexation; direct and indirect
photochemical reactions; microbial degradation and toxicity;
bacterial, algal, and fungal sorption; and volatilizatione
Loss of vinyl chloride from the aquatic environment by
volatilization appeared to be the most significant process
in its distribution.

This report was submitted in fulfillment of ROAP O4AEN,
Tasks 005 and 009, and ROAP O3ACQ, Task O09, at the
Environmental Research Laboratorys; Athens; Georgiae Work
was completed as of September 1975.

iii


A diagnostic input consisting of a pulse of vinyl chlo-
ride can produce a characteristic response for each compon-
ente This response is a very concise way of demonstrating
the behavior predicted by the system hypothesise The total
response to a pulse input contains all the information
necessary to characterize the system (10). Figures 15
through 17 show the component responses to a pulse input of
1 mg Ul! vinyl chloride to the epilimnion waters for the
model of Figure 6+« In Figure 18, the beginning of the slow
loss of vinyl chloride from the sediments can be seen after
about 60 dayse

The results of a pulse input of 1 mg UU? vinyl chloride
to the sediments are shown in Figures 19 through 21. The
slow but continuous loss of vinyl chloride from the
sediments is evident. This loss occurs to the air (rate + 7
x 1076 mg U7! day!) and to downstream waters (rate = 3.9 x
107° mg U7! day 1).

All of the results assume steady-state levels of biomass
components and particulates and do not include any low level
toxic effects or biomagnification (ices, selective retention
of vinyl chloride). From the results of these model
simulations it appears that vinyl chloride should not remain
in an aquatic ecosystem under most natural conditionse

25


x
Vinyl Chloride
in Atmosphere

| 442

x2

INPUT > Vinyl ini j———= OUTPUT
in

| 93,2

x3

Chemical and Biological | —_—_—_—_—_—_—==fj- OUTPUT
Reaction Products in Water

Figure 5. System model with worst case chemical and
biological transformation reaction ratese

11


0.662

Vinyl Chloride in Water

—-—--— Vinyl Chloride in Air

VINYL CHLORIDE, mg/1

0.331 [—

Figure 7. Lake simulation with best estimate model.

17


The system diagrams of Figures 4 through 6 theretore
were directly translated to a set of equations that can he
written in vector form as

SX 5 ax + BU q)

where the xy represent the variable quantities stored in the
boxes; the a; represent the rate coefficients for transfer
from box j to box i; and the uy represent the inputs to box
ie

The typical or sample lake is assumed to be 10% m? and
10 m deepe It has a residence time of 10 days and strati-
fies in summer with a metalimnion 0.5 m wide centered at a
S-meter depthe It is completely mixed above and below the
thermocline when stratified and completely mixed otherwise.
The typical or sample stream parameters were derived from
Tsivoglou and Wallace's (5) data on the Chattahoochee and
Jackson riverse

For the best estimate model, equation (1) reduces to

—2 = a x tu (2)

The rate coefficient value; 01,2: of the best estimate model
of the lake is a bulk gas exchange coefficient between water
and atmosphere of 06436 day 4 (6, Section VII of this
report )e The input was set at 1 mg Ul”! vinyl chloride in
the influent water as a reference value.

The ges exchange coefficient, 1,29 in the best estimate

stream model is 0.96 day ! (5, Section VI of this report),
and the input is again 1 mg U7! vinyl chloride.

13


Vinyl Chloride in
Epilimnion Water

——-— Vinyl Chloride Reaction
Products in Epilimnion

Water
1.0
3
£
a
s
S054 -
x=
So
—
S
=
>
“v~n
N
/ NL
oh ~r---
0 25 50
TIME, days

Figure 15. Stratified lake model's response to pulse input
of vinyl chloride to epilimnion water.

26


INPUT Vinyl Chloride OUTPUT
in Atmosphere

Elimination Reaction

Surface Active Agents
Products ——<— ee —— ——
Hydrolysis Reaction | | > Vinyl Chloride
Products l in Bacteria
Free Radical Reaction Vinyl Chloride in Water

Products ——

Vinyl Chloride in Algae

Direct Photochemical

Reaction Products [“———————

1 —— Vinyl Chloride
in Filter Feeders
Vinyl Chloride
Indirect Photochemical Sorbed on Particulates
Reaction Products ——————
Vinyl Chloride
" =
Microbial Degradation in Predators
Products —
Vinyl Chloride in
— Sediments 5 _
Coordination Complexes |—<$<—<_—_— —— ——_—_} Vinyl Chloride in

Figure 3-6 Working conceptual model of vinyl chloride
interactions in an aquatic systeme


x = amount (mg) of material sorbed per mg of

solution Cog - Cer where cy = initial
concentrat on)
m = dry weight (mg) of microorganisms per liter

Experimentally, the quantity of vinyl chloride sorbed
can be estimated as the difference between total VCM in the
system (¢,) and that in the supernatant at equilibrium Code
The concentration of organisms (m) required to detect a Ky
of 10 for a given c, of 25 mg VCM/l can be determined from
equation (3) by assuming a Ky of 10 and a value for cy,
slightly greater than the experimental error involved in VCM
determinations. Concentrations of microorganisms calculated
to give Ky 2 10 were used in our experiments and
supernatants were sampled at 30 minutes, 24 tours, and 48
hourse

Vinyl chloride did not sorb to a detectable extent to
any of the organisms tested——-the five bacterial
populations, Be subtilis, Fe harrisonii, the three fungal
populations, or Chlorella pyrenoidosa; the distribution

coefficients for all organisms were therefore less than 10.

In previous studies in our laboratory, the degree of
sorption of various pesticides to microorganisms was found
to correlate inversely with the water solubility of the
pesticidese The more water soluble compounds (malathion,
diazinon, parathion, and carbaryl) did not sorb to any
detectable extent, whereas the less water soluble compounds
(methoxychlor and toxaphene) did sorbe Since vinyl chloride
is more water soluble than the above insoluble pesticides,
its inability to sorb to the microorganisms would therefore
be expectede

Bacterial Degradation

Only mixed bacterial populations were used in the
degradation studies since they often show a greater facility
to acclimate than a single species culture.

The test cultures were monitored for decrease in VCM
concentration by direct injection of the aqueous culture
(organisms and media) into the glce Nutrient broth
concentration was decreased and VCM concentration was
increased at each transfere VCM concentration was monitored
for 20 hours between transferse No change in concentration
was detected at any VCM Level. At the end of this period
the bacterial populations were transferred to medium

52


ACKNOWLEDGEMENTS

The authors gratefully acknowledge the contributions of
their colleagues, John T-e Barnett, David Le Lewis, and Bill
Macae Helpful and constructive comment was received from
Ray Re Lassiter, James We Falco, and George Le Baughman.

The efforts of Shirley H. Hercules in editing and Anne

Le Warner and Carlyn Be Haley in typing are sincerely
appreciated.

ix


Vinyl Chloride in Filter
Feeding Organisms
(Hypolimnion)

—~-—-—- Vinyl Chloride in
Predator Organisms

—--——- Vinyl Chloride in
Omnivorous Organisms

VINYL CHLORIDE x 10°, mg/1

TIME, days

Figure 13. Stratified lake simulation of the model in
Figure 6.6

23


specific rate of exchange of vinyl chloride gas between
water and air is about twice that of oxygen.

59


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92325742, 1970.

62


VINYL CHLORIDE x 102, mg/1

Figure 10.

9.68

4.84

Vinyl Chloride in Water

—-—-— Vinyl Chloride
Degradation Products

T.o->>
on
=
7
/
/
/
]
|
/
/
/
v |
0 25 50
TIME, days

Stream simulation of the model of Figure Se

20


10

11-14

15-18

19-21

22

23

24

FIGURES

Composite representation of the analysis
procedures

Initial conceptual model of vinyl chloride
interactions in an aquatic environment

Working conceptual model of vinyl chloride
interactions in an aquatic system

Best estimate model of vinyl chloride in the
aquatic environment

System model with worst case chemical and
biological transformation reaction rates

System model of vinyl chloride in stratified
lake with a simple idealized food web

Lake simulation with best estimate model
Stream simulation with best estimate model
Lake simulation of the model of Figure 5
Stream simulation of the model of Figure 5

Stratified Lake simulation of the model in
Figure 6

Stratified lake model's response to pulse
input of vinyl chloride to epilimnion water

Stratified lake model's response to pulse
input of vinyl chloride to sediments

Vinyl chloride reaction vessel

Pathways for light induced decomposition of
vinyl chloride

Decomposition of vinyl chloride in water by

vi

10

11

12

17
18
19
20

21-24

26-29

30-32

35
42

47


Section

I

II

Tir

Iv

vI

vil

VIII

Conclusions and Recommendations
Introduction
System Analysis

Assumptions
Results and Discussion

Chemical Interactions

Materials and Methods
Results and Discussion

pH Studies
Oxidation Studies
Natural Waters
Complexation

Photochemical Interactions

Materials and Methods
Results and Discussion

Direct Photolysis
Indirect Photolysis

Microbiological Interactions

Materials and Methods
Results and Discussion

Sorption to Microorganisms

Bacterial Degradation

Toxicity to Bacteria
Physical Interactions

Materials and Methods
Results and Discussion

References

16
33

34
36

36
36

38
38

41

43
44

44
45

48

48
51

$1
52
53
54

55
55

60


The quantitative aspects of the possible behavior of
vinyl chloride in aquatic systems may be approximated by
simulation and analysis of a system model of a sample lake
and stream. The conclusions resulting from these
hypotheses, however, are only as good as the assumptions
made in their formulatione These assumptions may be changed
to incorporate new information or to apply the analysis to a
particular aquatic system.

ASSUMPTIONS

The most significant assumption in this type of analysis
is the model itself. The choices of components and their
couplings represent a mixture of logical analysis, physical
intuition, and personal biasese These choices affect the
parameters, inputs, outputs, and responses of the model.

A best estimate approximation of the behavior of vinyl
chloride in a sample lake or stream was obtained assuming
the most reasonable estimates of the rates of transformation
processes as determined from Laboratory resultse
Experiments indicated that rates for all processes except
volatilization are essentially zero (Section IVs; Vy VI, and
VII). This assumption results in the simplified model of
Figure 4.

To evaluate the boundaries of possible vinyl chloride
behavior, two additional system models were derived
describing extreme behavior at two levels of resolution. In
these worst case analyses, all chemical and biological
transformation processes were assumed to proceed at a rate
that is just below the level of measurement in the
experimental procedures used for their determinatione
Conditions in the aquatic environment (eceges turbulence,
stratification, sediment scouring) were assumed to be at the
extreme of the environmentally realistic range that would
cause worst case system responsese The system models of
Figures 5 and 6 were analyzed subject to these worst case
assumptionse

A set of linear, first-order ordinary differential
equations was assumed to be a reasonable mathematical appro-
ximation of the dynamic behavior of vinyl chloride in the
hypothesized structurese This is justified by recourse to
the theory of linearization about an operating path (4) and
assumes that vinyl chloride input represents a small system
perturbatione


TABLES

Worst case model parameters

Order of magnitude estimates for half-lives
for vinyl chloride reactions

Equilibrium constants for some compounds
structurally related to vinyl chloride

Rate coefficients for oxygen and vinyl chloride
gas exchange at four mixing levels

viii

15
37

40

57


Table 1.

WORST CASE MODEL PARAMETERS

89,63 49,7
89,8

810,63 410,7
810,83 410,9

45,65 45,7
85,683 85,9

Uptake by predator

Uptake by omnivore

Turnover rate of organisms

Symbol Interactions Value (day "')

1,2 Volatilization of vinyl 0.436
chloride

a3,2 Chemical and biological 0.115
degradation

ai1,4 Chemical and biological 0.115
degradation

e2,4 Transport across thermocline 0.0178

as.2 Transport across thermocline 0.0178

a6. 2 Uptake by filter feeding 0.000292
organisms

ave Uptake by filter feeding 0.000292
organisms

ass Uptake by benthic organisms 0.000292

9273 (1075)

763 (1075)

Oo1

asa Water to sediment transport 0.107 (10° 2)

aes Sediment to water transport 3.45 (107%)
z

a Loss from compartment a S44

u2 Input to water 1 ppm

Us Input to water 1_ ppm

15


EPA-600/3-76-001
January 1976 Ecological Research Series



mg t! vinyl chloride in water saturated with molecular
oxygen at elevated temperaturese After 12 hours at 85°C, no
degradation of the vinyl chloride could be detectede At
temperatures and oxygen concentrations in natural waters,
therefore, vinyl chloride will not be degraded by molecular
oxygen at a significant rate.

As anticipated, at elevated temperatures vinyl chloride
was degraded by hydrogen peroxidee At 85°C hydrogen
peroxide decomposes to give hydroxy radicals (HO*), which
react with vinyl chloride. With 1 x 10°72 M hydrogen
peroxide and 1 x 10°* M vinyl chloride, the reaction obeys
zero-order kinetics, indicating that decomposition of
hydrogen peroxide is the rate-determining stepe

The significance of this reaction pathway is difficult
to assess because no data are available concerning the
concentration and species of free radicals in natural
waterse These experiments do indicate that if reactive
radicals were present in natural waters at significant
concentrations, they may potentially degrade vinyl chloride.

Natural Waters

Vinyl chloride was shown to be chemically stable in two
natural water samplese No degradation could be detected in
Oconee River water (pH 6-1) and Okefenokee Swamp water (pH
4.2) after 41 hours at room temperature and at 85°C.
Assuming the pathways previously discussed, extrapolation of
the elevated temperature data to environmental conditions
would indicate a minimum half-life of at least one yeare
Although only two representative water samples were
employed, the results obtained are in agreement with
behavior predicted based on known chemical reactivity of
vinyl chloride.

Complexation

To study the effect of complexation with metal ions on
the persistence of vinyl chloride in water, three important
points should be considered:

e How strong are the complexes?

°¢ What are the concentrations of the metal species?
°¢ What are the concentrations of the competing ligands?

38


The reactions of vinyl chloride with chlorine and hypo-

chlorous acid should be studied under
vail in the chlorination processes of
ment plantse Also, the reactions of
vinyl chloride under these conditions

conditions that pre-
municipal water treat—
organics that may form
should be studied.


SECTION I

CONCLUSIONS AND RECOMMENDATIONS

A worst case system analysis of vinyl chloride behavior
in aquatic systems suggests that unrealistically high levels
of vinyl chloride inputs would be necessary to maintain
significant concentrations in these systemse However, given
extreme environmental conditions; aquatic sediments could
exhibit long-term storage of low levels of vinyl chloridee

Chemical degradation of vinyl chloride under pH's,
reactant concentrations, and temperatures common to the
environment should not be significant. Neither auto-
oxidation nor degradation by free radicals is important in
most natural waters at low vinyl chloride concentrations.
Increased persistence of vinyl chloride due to complexation
with Agt and Cut should be minimal. Data are not available
for consideration of other metal speciese

Experiments with distilled water, water from the efflu-
ent of a PVC plant, and two natural waters indicate that
photolysis of vinyl chloride is probably a slow process
under environmental conditionse

Vinyl chloride does not appear to be sorbed by
microorganisms, as indicated by laboratory experiments with
five mixed bacterial populations, three mixed fungal
populations, two axenic bacterial cultures, and one algae
The five mixed bacterial populations did not degrade the
vinyl chloride to any detectable extente Also, at vinyl
chloride concentrations up to 900 mg 171, no toxic effects
on the bacterial cultures could be detectede

The rate of bulk exchange of gaseous vinyl chloride bet-
ween atmosphere and water is about twice that of oxygene
Loss of vinyl chloride by volatilization from water is
therefore probably the most significant process in its
distribution.

The assumptions and consequently the conclusions of this
analysis may be invalid when vinyl chloride enters a re-
ceiving water as a component of a tar or sludge or when
large concentrations of surface active agents are present
with the vinyl chloride in water. Further study is neces-
sary for specific situations where these conditions existe


medium containing 6-0 g glucose per liter. Medium was
decanted and enough fungi were transferred to 5-nl graduated
centrifuge tubes with ground glass stoppers to give
approximately 5 g¢ dry weight of fungi per liter of water.

Chlorella pyrenoidosa was grown in Bensen-Fuller medium
containing 0.1% Hutner's trace element solution and
incubated on a shaker at 15°C under 170 ft-c of continuous
light. Cultures were centrifuged, washed three times, and
transferred to S-ml graduated centrifuge tubes with ground
glass stoppers for sorption studies to give approximately 4
ge dry weight of algae per Liter of water. To eliminate
corrections for volatilization of VCM to the air above the
solution, tubes were filled to the top and all data were
compared with data from control tubes (containing no
organisms ).

To determine dry weights of algae and bacteria used in
sorption studies, cultures were centrifuged and the
organisms were washed three timese The organisms were
quantitatively transferred to tared beakers and dried to a
constant weight at 90°C. Fungi were separated from test
cultures for dry weight determinations by filtering, first
through tared pre-filters, then through tared 0622 micron
Nucleopore filters, and by drying to a constant weight at
90°C.

RESULTS AND DISCUSSION

Sorption of Vinyl Chloride to Microorganisms

In systems in which sorption is linear (very low solute
concentrations), the simple distribution coefficient (Kg)
may be used to describe the extent of sorption of a compound
to microorganisms

x/m
Kio = > (3)
d ce
where c. = concentration (mg/mg) of solute in solution at

e equilibrium

51


H H H OH )
\ au tt i]
c=c => ~=fa-c-c-H] —~> CH,-C-H

\ HAO io 3

H cl H CL

This reaction is second order with its rate dependent upon
concentrations of both vinyl chloride and acide

Based on tkinetic studies in mixed systems, only a few
oxidative processes are potentially important for vinyl
chloride in the environment (14). Autooxidation (with
motecular oxygen) (16) is a possibility; but since its rate
is dependent upon the rate of homolytic cleavage of the
strong carbon-hydrogen bond, the rate of oxidation of vinyl
chloride would be slow.

Free radicals are anticipated to react with the carbon—
carbon double bond (14), resulting in oxidations However,
Since literature data are not available to evaluate the role
of free radicals in natural waters, extrapolation of
laboratory data to natural waters is tenuouse

The reactivity of vinyl chloride was studied, and known
structure-reactivity relationships and activation parameters
were used to evaluate the significance of the above pathways
for vinyl chloride disappearance in the environmente

MATERIALS AND METHODS

Vinyl chloride was obtained from Matheson Chemical
Company and used as receivede Distilled water was used in
all experiments except for natural water studiese The
Oconee River water sample was obtained in Athens, Georgia,
and filtered through a 0.22-y filter prior to use (pH 661).
The Okefenokee Swamp water sample was obtained at Kingfisher
Landing, Okefenokee Swamp, Georgia, and was used as obtained
(pH 42). Hydrogen peroxide was purchased from Baker
Chemical Companye

A special reaction vessel (Figure 22) designed to
eliminate volatilization, was made for these studies.

34


Vinyl Chloride in Hypolimnion

—-—--— Vinyl Chloride Degradation
Products in Hypolimnion

13.50 T ==
ae
S
=
=)
x
a
= 6.15 >
3
x=
oO
2
>
4
>
!
o 25 50
TIME, days

Figure 12. Stratified lake simulation of the model in
Figure 6+.

22


A survey of the literature did not disclose any equilibrium
constants for the formation of coordinate complexes between
vinyl chloride and metal ionse However, data for the
formation of complexes between structurally related olefinic
compounds and Agt and Cut (Table 3) indicate that electron-
withdrawing groups attached to the double-bonded carbon atom
of the olefin decrease the equilibrium constant. Assuming a
concentration of 10 mg 1”! for the silver-ethylene complex,
equilibrium calculations show the complex to be greater than
99% dissociated. Similarly, the cuprous-f-chloro-allyl
alcohol complex at 6.2 mg 74 is also greater than 99%
dissociated. The effect of other ligands common to the
aquatic environment, which would be competing for the metal
ions, are neglected in these calculationse Thus we conclude
that at low metal ion and vinyl chloride ion concentrations,
complexation by these metal ions is not importante

39


Vinyl Chloride in Epilimnion

—-—-—-— Vinyl Chloride Degradation
Products in Epilimnion

——-—— Vinyl Chloride in Sediments

0,176 = 1
7
/
+
/

= /
=) I
e i]
et |

1
S 0.0879 Ht} 4
x= f
° U
—_
> U
2
>

—_—s
_
0 —_— I
0 100 200
TIME, days

Stratified lake simulation of the model in

Figure 11.
Figure 6.6

21


—0.729

_
=
B -373 4 7
x
Ss
>
=
|
-1750
0.0803 —0.0419 —0,00354
Ko,, minTM

Figure 26. KX.

VOM versus K

2

at four mixing levelse

58


25

26

attack of free radicals generated by photolysis
(300 nm) of hydrogen peroxide

Apparatus for vinyl chloride degradation and
toxicity studies

EKvycy versus Xo, at four mixing levels

49

58


x

1
Vinyl Chloride
in Atmosphere
%32 | 12 {6,2
4% % %
Chemical and Biological Vinyl Chloride Vinyl Chioride in
Reaction Products in Water in Water Filter Feeding Organsims|
7 suf You
Chemical and Biological | gageeesnnens PA an %
Reaction Products in Water P| Vinyl Chloride . Vinyl Chloride in
in Water Filter Feeding Organisms |=——my
5 %9.6 { %y,7
% *o
Vinyl Chloride in Vinyt Chloride in
4 " z e
Benthic Organisms |TM==p{ %,8 | Predator Organisms
10,7
%s *10
Viny! Chloride | %10.¢ Lemmged Vinyl Chloride in faateee
in Sediments Omnivorous Organsims
45,10
46,9
95,7

Figure 6-2 System model of vinyl chloride in stratified
lake with a simple idealized food webe

12


HOLE

tr
SCREW car iy
| RUBBER SEPTUM

came “TEFLON FILM LINER

Figure 25. Apparatus for vinyl chloride degradation and
toxicity studies.

49


estimate the specific rates for each of the four levels of
mixinge These specific rates are presented in Table 4 with
their 95% confidence intervals. A linear regression of Kvem
on Ko, resulted in the equation

= 2. 7
Kyou 2.30 Ky, (7)
giving a constant ratio of
K
Pee = 2.30 + 0.31 (8)
0

2

at a 95% level of confidences The constant ratio line and
ratios at each mixing level are graphed in Figure 264

The ratio of gas exchange coefficients may also be
estimated as the reciprocal of the ratio of molecular
diameters (9). Two different values for the vinyl chloride
diameter may be obtained depending upon the method by which
it is calculatede The diameter calculated using a critical
volume of 168-9 ml mole! (44) in the van der Waals equation
is 3.55 A. Assuming a molecular diameter for oxygen of 2.95
i, the resulting ratios of gas exchange coefficients using
the two different diameters are

VeM = 0,83 and 0.87 (9)

respectively.

The experimentally determined estimate of the ratio of

gas exchange coefficients {Kicu’*,? indicates that the
2

56


Vinyl Chloride in Sediments
(Extended Time Scale)

6.66
T 1
S
i=
S
x
a
53.33 EL 4
g
=
oO
—_
>
z
>
0 |
0 50 100
TIME, days

Figure 18. Stratified lake model's response to pulse input
of vinyl chloride to epilimnion water.

29


Vinyl Chloride in Sediments

1.000 1
=
i=
8
S 0.982 + 4
=x
oO
a
=
2
>
0.963 |
0 50 100

TIME, days

Figure 19. Stratified lake model's response to pulse input
of vinyl chloride to sediments.

30


Indirect Photolysis

Although direct photolysis (Mechanism I) is immeasurably
slow, the literature indicates that the Light-induced
transformations of vinyl chloride could occur through
indirect pathways (Mechanisms II-IV)e For example,
substances found dissolved in certain natural waters were
found to greatly accelerate the photodecomposition of some
pesticides (39, 40). Photolysis experiments were therefore
conducted in natural waters and in distilled water
containing model photosensitizers that absorb Light of
wavelengths > 300 nm

Vinyl chloride was not readily degraded by singlet
oxygen, an excited form of oxygen generated by methylene
blue photosensitization. However, in the presence of
acetone, a high-energy triplet sensitizer, or hydrogen
peroxide, a free radical source, VCM decomposed rapidly when
irradiated with ultraviolet Light. The disappearance
quantum yield (313 nm) for the acetone-sensitized reaction
(3.0 x 1072 M VCM) was 0675. A colorless precipitate formed
during photolysis, but it was not identified.

Since the major photochemical process for triplet 1,2-
dichloroethylene and other mono-olefins involves
isomerization (30), twisting about its carbon-carbon bond
would be expected to be the primary process for triplet VCM.
Other studies have indicated that reaction between triplet
ketones and olefins (41) to form oxetanes is not
particularly efficiente Therefore the high disappearance
quantum yield for the acetone-sensitized photolysis of VCM
was surprisinge The photolysis may involve inefficient
homolysis of the carbon-chlorine bond of triplet VCM;
followed by free-radical polymerization of VCMy iee@es most
of the VCM would be consumed by secondary thermal reactionse

The importance of photosensitization via energy transfer
for the disappearance of VCM in the environment is difficult
to predict. Such sensitization occurs efficiently only when
the triplet state energy of the sensitizer equals or exceeds
that of the acceptor, ieee, VCMe Since the triplet state
enérgies of mono-olefins are very high (78-82 kcal mole!)
(38), only high energy sensitizers such as acetone (triplet
energy 80 kcal mole!) are effective. Unfortunately, Little
is known about the concentrations and distribution of high-
energy sensitizers in the aquatic environment. The matter
is further complicated by the fact that competing energy
acceptors such as dissolved oxygen are also present in the
aquatic environmente

4s


0.896

0.448

VINYL CHLORIDE, mg/!

Figure 8.

Vinyl Chloride in Water

—-—--— Vinyl Chloride in Air

TIME, days

Stream simulation with best estimate model.

18


SECTION VI

MICROBIOLOGICAL INTERACTIONS

In natural waters, the interactions of vinyl chloride
with Living organisms must also be considered as a possible
mechanism for disappearance of the compounde Two possible
pathways were considered--~sorption to microorganisms and
degradation by bacteriae The toxicity of the vinyl chloride
to bacteria was also investigatede

MATERIALS AND METHODS

Five mixed bacterial populations, three mixed fungal
populations, and two single organism cultures (Bacillus
subtilis, and Elavobacterium harrisonii) were isolated from
natural aquatic systems in and near Athens, Georgiae An

alga, Chlorella pyrenoidosa;, was obtained from the Starr
Collection, University of Indiana, Bloomington, Indianae

A saturated solution of vinyl chloride was prepared by
bubbling the gas into sterile distilled water for one houre
Vinyl chloride solutions for the bacterial degradation and
toxicity studies were prepared by aseptically diluting the
saturated solution to varying extents with a solution of
nutrient broth that was diluted 1:20, 1:40, 1:80, or 1:100
in basal salts medium (42). The pH of the medium was 6-9.
For the sorption studies, the saturated VCM solution was
diluted with distilled water.

Analyses for VCM were done by direct gas-liquid
chromatography (glc) using a Tracor MT-220 Chromatograph
equipped with dual flame ionization detectors. Peak areas
were obtained using a Varian Aerograph Model 477 integrator.
VCM amounts were determined by comparison of glc peak areas
from the experimental solutions with those from VCM gas
standards in air prepared by MG Scientific Company. VOM
eluted in approximately two minutes as a single; sharp
symmetrical peak from a 1-5 meter Porapak Q (Waters
Associates, Ince) column (4 mm ID) at an oven temperature of
125°C, an injection port temperature of 215°C, and a carrier
gas (nitrogen) flow rate of 90 ml/min.

For the degradation and toxicity studies, 250-ml flasks
with side arms and screw caps, as illustrated in Figure 25,

48


Table 4. RATE COEFFICIENTS FOR OXYGEN AND VINYL CHLORIDE
GAS EXCHANGE AT FOUR MIXING LEVELS

Vortex - -
dente Xo, (minTM?) Kycy (min 1)
0 -3054( 1073 )+2628(107*) | —3203( 1073 +2.74( 107%)
1.5 1.24 1072 4124501073) | -1.29( 1072 41.22 1073)
5.0 -3.85( 1072 )£1.16(1072) | -8219( 1072 )41.06( 10° 3)
10.0 —8.03( 1072 )#3-86(1072) | -1-75( 107! )47-88( 102)

57


DISCLAIMER

This report has been reviewed by the Environmental
Research Laboratory, U.S. Environmental Protection Agency,
and approved for publication. Mention of trade names or
commercial products does not constitute endorsement or
recommendation for use.

ii


LE

Table

26 ORDER OF MAGNITUDE ESTIMATES FOR

FOR VINYL CHLORIDE REACTIONS

HALF-LIVES

Literature data Estimated ty
Tempe Maximum rate at
Reaction (2c) Reactant | constant MTM! sec”! 2sec®
Elimination® 95.53 Methoxide 107-7 <10 yr
Substitution? {130 C2Hss- 1079 <10 yr
Addition® 25 H20 107-* <iyr
Addi tion? 25 Cle 1071 140 hr
Addition® 25 HOCL 1072 1000 hr
__Hydrolvsis’ 1120 H29 No RX <10 yr.

aReference 17+
bReference 18,
thiol.
CReference 19,
Reference 20,
chlorinee
Reference 21,

methanol solvent, 107
reaction of 1-chloropropene in ethanol at 1 x 1073M

1 mg UU! hypohalous acide

£

Reference 15.

3M methoxide.

acid catalyzed hydration at pH 3.
1,3,3-trichloropropene in aqueous acetic acid---1 mg 17!

Scalculated assuming pseudo first-order kineticse

hypohalous acid addition to allyl alcohol at pH 4.5---


7 SEPTUM

TEFLON STOP
a OPCOCK

\_H

cm fe)

> pe INSIDE DIAMETER 6 MM

Nr

VOLUME APPROX. 2.9 ML

Figure 22. Vinyl chloride reaction vessel.

35


1.

3.

Se

Ge

Te

9.

REFERENCES

Ue Se Environmental Protection Agencye Vinyl Chloride
Monitoring Near the Be Fe Goodrich Chemical Company in
Louisville, Kentuckye Surveillance and Analysis
Division, Athens, Georgiae June 1974. 45pe

Gillett, Je Wey Je Hilly IV; Ae We Jarvinen, and We Pe
Schoore A Conceptual Model for the Movement of
Pesticides Through the Environmente National
Environmental Research Center, Corvallis, Oregone EPA-
660/2-74-024e December, 1974. 80p.

Thruston, Ae Dey Jre and Ae We Garrisone Stability of
Vinyl Chloride Monomer in Watere Internal Report,
Southeast Environmental Research Laboratory; Athens,
Georgiae 1974¢ 2p.

Directory Se We and Re Ae Rohrere Introduction to
System Theorye New York, McGraw Hill, Incey 1972.
441ipe

Tsivoglou, Ee Ce and Je Ke Wallacee Characterization of
Stream Reaeration Capacitye Georgia Institute of
Technology. Office of Research and Monitoring,
Washington, De Ce EPA-R3-72-012. October, 1972-¢ 3115p.

Bacay, Re Gey Me We Lorenzeny Re De Muddy and Le Ve
Kimmel.e A Generalized Water Quality Model for Eutrophic
Lakes and Reservoirse Pacific Northwest Laboratoriese
Richland, Washingtone 2118301602. Office of Research
and Monitoring, Ue Se Environmental Protection Agencye
August, 1974. 140p.

Hutchinson, Ge Ee A Treatise on Limnology. Volume Ie
New York, John Wiley and Sons, Ince, 1957. 1015p.

Russell—-Hunter, We De Aquatic Productivitye Toronto,
Collier Macmillan, 1970. 305p.

Tsivoglou, Ee Ce Tracer Measurement of Stream
Reaeratione Georgia Institute of Technology.
Washington, De Ce Water Pollution Control

Administratione Juney 1967. 86pe

60


INPUT

Vinyl! Chloride in Atmosphere

Elimination Reaction
Products a a

Direct Photochemical
Reaction Products

Hydrolysis Reaction
Products

Free Radical
Reaction Products

Figure 2.

Vinyl Chloride in Water

4

Vinyl! Chloride
Sorbed on Particulates

Viny! Chloride
in Sediments

Indirect Photochemical
Reaction Products

Microbial Degradation
Products

Vinyl Chloride in Food
Web Organisms

Initial conceptual model of vinyl chloride
interactions in an aquatic environment.



100
°
2
2 80--
=
a re)
= 60/- NG
>
= Nn
8 ob °
&
a.
20;—- NN
| ! |
% 1 2 3
TIME, hrs

Figure 24. Decomposition of vinyl chloride in water by
attack of free radicals generated by photolysis
(300 nm) of hydrogen peroxides

47


containing only basal salts and 54 mg 17! VCM without an
additional carbon sourcee These cultures were monitored

daily for one weeke No degradation was detected at any time
in any of the cultures.

Byington and Liebman (43) have shown that
trichloroethylene was transformed to chloral hydrate by rat,
rabbit, and dog liver microsomes in a _ reaction requiring
NADPH and oxygene Based on the structures of the compounds
and the requirement of NADPH, alcohol dehydrogenase may be
the active enzyme. If soy degradation of VCM by bacteria
could be possible via the following pathway:

H oO: 4H Alcohol HH wo
7 1
GC > Gc Dehydrogenase, HG ~G-OH —>  B-G-C-H
yo N \ |

HCl 0 NADPH, H cl OH cl

If the bacteria were capable of degrading VCM by this
pathway, a system in which oxygen was not a limiting factor
would be needede The closed flask systems described earlier
could Limit the oxygen in the systeme Therefore, six one-
liter flasks containg the five bacterial populations in 1:40
nutrient broth and an uninoculated control were bubbled with
0.1% VCM in air for 96 hours and monitored for possible
products by glc analysis at low column temperature using
FIDe No degradation products were detected in any of the
culturese

Toxicity of Vinyl Chloride to Bacteria

The toxicity of VCM to five actively growing bacterial
populations was testede Testing could not be done at VCM
concentrations up to its solubility in water (1700 mg 11)
because of the difficulty in supplying the bacteria with
sufficient oxygen for growth above a VCM concentration of
900 mg Ua. Because even at 900 mg U1 VCM the oxygen
concentration was low, a low nutrient broth concentration
was used also (1:100) to insure that any differences in
growth would be due to the presence of VCM rather than
insufficient oxygene No difference could be detected
between bacterial growth in cultures and in test cultures
containing up to 900 mg 11 VCMe The VCM was therefore not
toxic to bacteria at these concentrations.

53


SECTION III

SYSTEM ANALYSIS

For the purposes of the present study the behavior of
vinyl chloride in an aquatic system may be assumed to be a
function of four aspects of the system:

e the components of the system with which vinyl chlo-
ride may associate or react (eeges water, organisms,
other chemical species);

e the interactions or coupling pathways among these
components;

e the characteristics of the interactions (ecege, magni-
tude, rate, saturation); and

e the rates of vinyl chloride inputs to the system.

The conceptual model of Figure 2 was used to organize
the. facts and assumptions into an initial system hypothesis
as described by Gillett et ale (2). This model represents
the components and interaction pathways considered to be
important in a study of vinyl chloride in an aquatic systeme
This initial conceptual model was transformed to the
conceptual model of Figure 3 through consideration of pre-
liminary studies of vinyl chloride (3), available data on
vinyl chloride and analogous compounds, and constraints on
the scope of the investigation,as defined by the nature of
the problem.

The working conceptual model (Figure 3) indicated the
need for quantitative characterization of the chemical, bio—
logical, and physical interactions between the componentse
The transport process dynamics have been evaluated in pub-
lished descriptions of the behavior of the transport media
Cecges particle, fluid, and trophic dynamics). The
transformation process dynamics were evaluated by chemical,
biological, and physical experimentatione

The qualitative conceptual model (Figure 3) and the
associated quantitative interaction descriptions can be
logically reduced or expanded to provide a hierarchy of
system modelse These system models can be represented
mathematically and evaluated by simulation to provide
descriptions of vinyl chloride behavior at various levels of
abstraction or generality.


EPA-600/3-76-001
January 1976

DYNAMIC BEHAVIOR OF VINYL CHLORIDE

IN AQUATIC ECOSYSTEMS

by

James Hill Iv, Heinz P. Kollig,
Doris F. Paris, N. Lee Wolfe,
and Richard G. Zepp

Environmental Research Laboratory
U.S. Environmental Protection Agency
Athens, Georgia 30601

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

ENVIRONMENTAL RESEARCH LABORATORY
ATHENS, GEORGIA 30601


VINYL CHLORIDE x 10?, mg/I

Figure 17.

3.62

1,81

Vinyl Chloride in Hypolimnion
Water

———-—-— Vinyl Chloride in Sediments

Vinyl Chloride Reaction
Products in Hypolimnion
Water

—+——-—— Vinyl Chloride in Filter
Feeding Organisms
(Epilimnion)

TIME, days

Stratified lake model's response to pulse input
of vinyl chloride to epilimnion water.

28


Complexation of vinyl chloride with silver or copper was
assumed to be negligible since typical Cut and Agt concen-
trations in aquatic systems are less than 30 mg m *, as much
as 80% of which is adsorbed onto organic colloids (7). In
addition, complexation would probably be very rapid and
reversiblee Finally, the conceatration of vinyl chloride in
the air above the water was assumed to be maintained at
essentially zero by surface replacement.

RESULTS AND DISCUSSION

The concentration of vinyl chloride in the water and the
cumulative loss to the air for the best estimate model
(Figure 4) of the sample lake are shown in Figure 7-« These
results are for a vinyl chloride input of 1 mg lTM! and a
fractional input of 10% of the total water volume. A
similar result for a volume of water in the sample stream as
it travels downstream is indicated in Figure 8e These
results indicate that with a volume input of 10% water per
day containing 1 mg U7! vinyl chloride, the concentration of
vinyl chloride in the sample stream and Lake would be less
than 002 mg l!.

If the chemical and biological reaction pathways with
worst case rates are added to the preceding examples (Figure
5), the resultant distribution of vinyl chloride is as
indicated in Figures 9 and 10. It should be noted that in
this worst case no losses of degradation products other than
washout or dilution are postulated. Even s0, the
degradation products reach a steady-state concentration
below 0.3 mg tTM!.

The behavior of vinyl chloride in the worst case model
of Figure 6, which represents a stratified lake with a
simplistic food web, is indicated in the graphs of Figures
11 through 14. The results are self-explanatory except for
the concentrations in sediments and benthic organisms. The
assumptions of diffusion-limited exchange between water and
unmixed Lower sediment layers and of Lack of scour dictate a
relatively long half-life for vinyl chloride in the
sediment-benthic organism-predator-ominivore cycle Cty = 3
yr )e With these assumptions the vinyl chloride
concentration in the sediment approaches a steady-state
value of 06358 mg U7! in about 15 yearse The vinyl chloride
in benthic organisms reaches a steady-state value of 0.013
mg 1”! in the same time period while the concentrations in
other organisms are lesse

16


RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U.S. 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 formation, 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.

This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.


Table 3. EQUILIBRIUM CONSTANTS FOR SOME COMPOUNDS
STRUCTURALLY RELATED TO VINYL CHLORIDE®

Olefin (L) Metal (M) log k_
Ethy Lene Agt 1.935
Trans-—dichloroethylene Agt -0.509°¢
Cis-dichloroethylene Agt -0.796¢
Allyl alcohol Agt 1.154
Allyl alcohol cut 4.72¢
B-chloroallyl alcohol Cut 1.34¢

* (ML)

(LL » where La = number of ligands present.
n-1

breterence 22.
CReference 23.
Reference 24.
Reference 256

40


6.59

3.29

VINYL CHLORIDE x 104, mg/I

Vinyl Chloride in Filter
Feeding Organisms
(Epilimnion)

——-— Vinyl Chloride in
Benthic Organisms

7
7
7
7
7
4 —_
7
7
7
a
7
v4
7
7
7
a
4
|
25 50
TIME, days

Figure 14. Stratified lake simulation of the model in

Figure 6.

24


SECTION IV

CHEMICAL INTERACTIONS

No reference to studies of the degradation of vinyl
chloride in water could be found in the literature.
However, considerable data are available concerning the
chemistry of vinyl chloride and related compounds that can
be extrapolated to reaction conditions anticipated in the
environment. Evidence supporting such extrapolations was
obtained in a few preliminary experiments.

Four pathways were postulated as potential mechanisms
for chemical degradation or alteration of vinyl chloride in
the environment: substitution (11), elimination (12),
addition (13), and oxidation (14).

In nucleophilic substitution, the chloride ion is
displaced by a nucleophilic species (Nu) (11). Reactive
nucleophiles common to the aquatic environment are amines,
thiols, water, and hydroxide ione The reaction can be
either first or second order depending on the specific
mechanisme

The most probable elimination reaction in the
environment is one in which hydrogen chloride is eliminated
from vinyl chloride in the presence of bases producing
acetylene (12). This is a second-order reaction and the
rate is dependent upon the concentrations of both vinyl
chloride and basee The most significant base present in
natural water would be hydroxide ion:

oN 4 ~ -
c=Cc Base (OH HC=CH + Cl
, N

The addition reaction most likely to occur to vinyl
chloride in the aquatic environment is the addition of water
across the carbon-carbon double bond, catalyzed by acid
(13).

33


Vinyl Chloride in Water

——-— Vinyl Chloride
Degradation Products

0.274 ——
aa
v4
7
S
=
i"
S 0.137 a
x=
Oo
—
>
2
>
0 _t
25 50
TIME, days

Figure 9. Lake simulation of the model of Figure 5.

19


SECTION II

INTRODUCTION

Vinyl chloride (CH2 = CHCl), a colorless, highly flam-
mable gas, is used primarily in the production of the resin,
polyvinylchloride (PVC)e The PVC is then used in the manu-
facture of many synthetic plastics and rubberse Vinyt
chloride monomer (VCM) is therefore present in many
manufacturing operations and, because water is used as a
medium in the polymerization reaction, it is also a possible
contaminant of waste water discharged from these plantse

In recent studies, chronic exposure to VCM has resulted
in Liver injury to Laboratory rats and rabbitse Also; some
workers in PVC plants have contracted angiosarcoma of the
liver (1). Because of its possible harmful effects on
humans and other Living organisms and the ubiquitous nature
of vinyl chloride in the manufacturing industry; the behav-
ior of VCM in aquatic ecosystems has come under critical
studye

The present study was undertaken to investigate the be-
havior of vinyl chloride in aquatic systems under conditions
simulating large inputs of VCM from industrial sources. The
study involved the use of a conceptual model of vinyl
chloride interactions in aquatic systems; physical,
chemical, and biological experiments with vinyl chloride;
mathematical models; and system analysise The relationships
among the various facets ot the study are represented in the
diagram in Figure 1.

The physical, chemical, and biological interactions of
vinyl chloride with the components of aquatic systems deter-—
mine the behavior of vinyl chloride in the systems The
individual interactions can be characterized quantitatively
by Laboratory experimentation and the behavior of VCM within
an aquatic system can be approximated by simulation of a
system model. An initial conceptual model of the
interactions of vinyl chloride in an aquatic environment,
developed as described by Gillett et ale (2) is represented
by the compartment diagram in Figure 2- In the diagram the
boxes represent storage of vinyl chloride or its reaction

products and the arrows represent transport or
transformation processese


rate of oxygen reaeration to eliminate the need for
measurement of turbulence and to relate vinyl chloride
volatilization to available environmental determinations of
oxygen reaeratione

For comparison, the ratio of specific rates was also
calculated using estimates of molecular diameter.

MATERIALS AND METHODS

Nitrogen-sparged, deionized water (900 ml) and saturated
vinyl chloride solution (10 ml) were added to each of four
beakers in an exhaust hood. The contents of beakers 1, 2,
3, and 4 were stirred to create vortices with depths of 0
(quiescent), 1.5 cmy 5 cm, and 10 cmy respectively. Oxygen
and vinyl chloride concentrations were measured every 10
minutes for 180 minutes using a dissolved-oxygen meter and a
gas chromatograph. Six replications of these experiments
were performed.

RESULTS AND DISCUSSION

The gas exchange dynamics at the interface were
represented as a first-order approach to equilibrium using
the equation

se = K(C,-C) (6)

where gas concentration
time
specific rate

saturation concentration

c
t
K
cs

The concentrations of oxygen and vinyl chloride for each
beaker in each replicate were used to determine the sums of
squares for the best least squares fit to the logarithmic
form of the solution to equation 6- The corrected sums of
squares for all beakers stirred alike were peoted to

55


SECTION V

PHOTOCHEMICAL INTERACTIONS

Several possible mechanisms exist for the decomposition
of vinyl chloride by Light (Figure 23). Mechanism I, direct
photolysis, involves direct absorption of light by vinyl
chloride followed by reaction from its excited state (VCM)*.
Several studies have indicated that vinyl chloride in the
vapor phase decomposes when irradiated with very short
wavelength ultraviolet Light (< 200 nm) (20, 27, 28). The
primary reaction processes are homolysis of the carbon-
chlorine bond yielding a chlorine atom and elimination of
molecular HCl. Twisting around the double bond, an
undetectable reaction, may also occure

Mechanism Il, photosensitized reaction via energy
transfer, involves absorption of light by a triplet
sensitizer followed by energy transfer to vinyl chloride to
form its first excited triplet state, (VCM)*. Studies by
Bellas et ale (29), for example, indicated that photolysis
of vinyl chloride can be sensitized in the vapor phase by
mercury atomse The authors concluded that in this case, the
primary photochemical process for triplet VCM in the vapor
phase involved elimination of molecular HCle However,
homolysis of the carbon-chlorine bond could not be ruled out
by their datae In solution, the major photoreaction for
triplet chlorinated olefins was found to involve twisting
around the double bond (30)e

Mechanism IIt, which we have called chemical
sensitization, involves direct chemical reaction between
sensitizer and olefine Such reactions are known to occur in
the condensed phase with simple olefins and electronically
excited ketones (31).

Mechanism IV, free radical decomposition and
polymerization of VCM initiated by photochemical homolysis
of a species like a peroxide, is also a possible pathwaye
Examples of the Light-initiated polymerization of vinyl
monomers are discussed by Walling (32)- Uri and co-workers
found that polymerization of vinyl monomers can be
"photosensitized" by chlorophyll (33) and by iron complexes
(34, 35)6 The "photosensitization" in these cases clearly
did not involve energy transfer, but rather the generation
of free radicals followed by polymerization (Mechanism IV).

41


The photodegradation of vinyl chloride was studied to
determine whether the above processes are possible in the
aquatic environment, and whether their rates, if they occur,
are sufficiently high to compete with other processes.

MATERIALS AND METHODS

Vinyl chloride gas from Matheson Company was used
without further purification. Laboratory distilled water
was redistilled from basic permanganate immediately prior to
use@e

Natural waters were obtained from the Oconee River in
Athens, Georgia, and the Okefenokee Swamp (Big Water Lake)
in South Georgiae Commercial humic acid was obtained from
Aldrich Chemical Company.

Stock solutions of vinyl chloride were prepared in small
bombs equipped with gas-tight Teflon stopcockse Aliquants
of VCM in gas-tight syringes were added to the bombs that

were completely filled with known volumes of carbon
tetrachloride; the gas rapidly dissolved into the CCl4.
Aqueous solutions were prepared following the same

procedures; the concentration in water was then measured
exactly by comparison to the CClqe stock solutionse Analyses
for VCM were performed by gas-liquid chromatography on a 2 m
x 0632 cm glass column packed with 0.4% Carbowax 1500 on
Carbopack Ae The column was cured by heating at 200°C for
48 hours with slow purging by nitrogene

Glce analyses were performed on a Tracor MT=-220
Chromatograph using a flame detector. Photolysis studies
were conducted on a rotating turntable apparatus, described
in detail by Moses, Liu, and Monroe (36). A 450-watt high-
pressure mercury lamp was the Light source. The ultraviolet
spectrum of VCM in water was obtained with a Perkin-Elmer
602 Digital Spectrophotometer using a specially constructed
quartz cell equipped with a gas-tight Teflon stopcocke AUL
photolysis studies were carried out in reaction cells
equipped with gas-tight Teflon stopcockse Controls
established that no leakage of VCM occurred from these cells
over a period of at least two weekse

Kinetic studies were generally carried out at VCM
concentrations of 10 to 20 mg Ul '. The light from the
mercury lamp was filtered through a 3 mm-thick Pyrex sleeve
(cutoff at 300 nm) for most of the studiese Singlet oxygen

43


A system analysis based upon the conceptual model was
used to estimate the behavior of vinyl chloride in aquatic
systems under both typical ("best estimate") and extreme
("worst case") conditions. The rates of the various
possible transport and transformation processes were
determined in the Laboratorye