Document MGNdMo227VR64ZQOqa5j298xa
EPA-600/3-76-001 January 1976
PB 249 302 Ecological Research Series
DYNAMIC BEHAVIOR OF VINYL CHLORIDE IN AQUATIC ECOSYSTEMS
Popreducd bv
NATIONAL TECHNICAL
INFORMATION SERVICE
U5
C'*&*/**#'*
al VA
C2oZ*>"*5"' *'**
Environmental Research Laboratory Office of Research and Development U.S. Environmental Protection Agency
Athens, Georgia 30601
.A
COLORITE 017191
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.
/
COLORITE 017192
EPA-600/3-76-G01 January 1976
DYNAMIC BEHAVIOR OF VINYL CHLORIDE IN AQUATIC ECOSYSTEMS
by Jamas 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 ih
COLORITE 017193
ABSTRACT
To valuat* the behavior of vinyl chloride In aquatic
co*yste*r beat estimate and worst cane nodela of lake and
atreaa ecosystems were analyzed through
the
uaa
of
athenatleal
simulation*
The
characteriatlca of the
chemical* biological* and physical transformationa of vinyl
chloride
indicated
in the modela were determined by
laboratory experimentation and extrapolation of reaction
data for almilar compounds* Theae transformationa Included
oxidation* substitution* elimination* hydrolysis* and free
radical
reactions;
complexation*
direct and indirect
photochemical reactions; microbial degradation and toxicity*
bacterial* algal* and funsal sorption* and volatilization*
Loss of vinyl chloride from the aquatic environment by
volatilization appeared to be the most algnifleant process
in Its distribution*
This report was submitted in fulfillment of ROAP 04ABM* Tasks 005 and 009* and ROAP 03ACQ* Task 009* at the Environmental Research Laboratory* Athens* Oeorgia* Vork was completed as of September 1975*
iii
i*
COLORITE 017194
CQHTfiflta
Section
I Conclusions and Recoanendations
II Introduction
III
Systes Analysis
Assunptions Results and Discussion
IV Chesical Interactions
ui
1 3
7
9 16
33
V VI VII
Materials and Methods Results and Discussion
pH Studies Oxidation Studies Natural Waters Coaplsxation
Photochemical Interactions
Materials and Methods Results and Discussion
Direct Photolysis Indirect Photolysis'
Microbiological Interactions
Materials and Methods Results and Discussion
Sorption to Microorganisms ^Hti&jkSpstorial Degradation
to Bacteria
Interactions
^Mnitorials and Methods Results and Discussion
34 36
36 36 38 38
41
43 44
44 45
48
48 SI
51 52
53
54 55 55
VIII
References
v
60
Preceding page blank
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SECTION I CONCLUSIONS AND RECOMMENDATIONS
A worst cos* Bystea analysis ol vinyl chloride behavior In aquatic systasa suggssts that unrealistically high levels ol vinyl chloride inputs would toe necessary to saintain significant concentrations in these systems* However* given extreme environmental conditions* aquatic sediments could exhibit long-term storage of low levels of vinyl chloride*
Chemical degradation of vinyl chloride under pH*s*
reactant concentrations* and temperatures common to the
environment
should not toe 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 complexstion
with Ag+ and Cu* should be minimal* Data are not available
for consideration of other metal species*
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 conditions*
Vinyl
chloride
does not appear to be sorbed by
microorganisms* as indicated toy laboratory experiments with
five
mixed
bacterial populations* three mixed fungal
populations* two axenie bacterial cultures* and one alga*
The five mixed bacterial populations did not degrade the
vinyl chloride to any detectable extent*
Also* at vinyl
chloride concentrations up to 900 mg l"1* no toxic effects
on the bacterial cultures could be detected*
The rate of bulk exchange of gaseous vinyl chloride bet
ween atmosphere and water is about twice that of oxygen*
Loss
chloride by volatilization from water is
theref
ly the most significant process in its
dlstrl
Th ons and consequently the conclusions of this analysis wmy be invalid when vinyl chloride enters a re ceiving water as a component of a tar or aLudge 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 exist*
1
COLORITE 0X7X98
SECTION II INTRODUCTION
Vinyl chloride (CHa = CHCl), a colorless* highly flam
mable gas* is used primarily in -the production of the resin*
polyvinylchloride (PVC). The PVC is then used in the manu
facture of many synthetic plastics and rubbers*
Vinyl
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 plants*
In recent studies* chronic exposure to VCH has resulted in liver injury to laboratory rats and rabbits* Also* some workers in PVC plants have contracted angiosarcona 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 study*
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 analysis* The relationships
among the various facets of 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 system* The
individual interactions can be characterized quantitatively
by lshoreexperimentation and the behavior of VCM within
an agu*|aHnwtee can be approximated by simulation of a
system
An initial conceptual model of the
interac^^HSt vinyl chloride in an aquatic environment*
developstlHflHlpMteribed by Gillett gi al (2) is represented
by the r ift^fsirtmen t 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 processes*
3
COLOR!TE 017199
TT
INPUT
Vinyl Chloride in Atmosphere
Hydrolysis Reaction Products
Free Radical Reaction Products
Vinyl Chloride in Water
_u *
Vinyt Chloride Sorbed on Particulates
_L 1 >
Vinyl Chloride in Sediments
OUTPUT
_L
Direct Photochemical Reaction Products
Indirect Photochemical Reaction Products
Microbial Degradation Products
Vinyl Chloride in Food Web Organisms
Figure 2* Initial conceptual model of vinyl chloride Interactions in an acruatic environment*
COLORITE 017200
SECTION III STSTBlf ANALYSIS
For th* purposes of ths present study the behavior of vinyl chloride In sn aquatic system may be assumed to be a function of four aspects of the system:
* the components of the system with which vinyl chlo ride may associate or react (gag.* watert organisms* other chemical species);
* the interactions or coupling pathways among these components;
* the characteristics of the interactions ( g*g* * magni tude* rate* saturation); and
* the rates of vinyl chloride inputs to the system*
The conceptual model of Figure 2 was used to organise
the facts and assumptions into an initial system hypothesis
as described by Oillett a! al* (2)* This model represents
the components and interaction pathways considered to be
important in a study of vinyl chloride in an aquatic system*
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 characterisation of the chemical* bio
logical* and physical interactions between the components*
The transport process dynamics have been evaluated in pub
lished descriptions of the behavior of the transport media
(g*g*
particle*
fluid*
and trophic dynamics)
The
transformation process dynamics were evaluated by chemical*
biological* and physical experimentation*
The^&sjiMHtative conceptual model (Figure 3) and the
ansocisijHKf'VUsatitative interaction descriptions can be
logieatiH^Hliipducad or expanded to provide a hierarchy of
system fflRpiftir*
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*
7
COLORITE 017201
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 formulation* 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 biases* 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
results*
Experiments indicated that rates for all processes except
volatilization are essentially zero (Section IV* V* 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 aasuawd to proceed at a rate
that is Just below the level of measurement In
the
experimental
procedures
used for their determine!ion*
Conditions In the aquatic environment (g*g** turbulence*
stratlfication* sediment scouring) were assumed to be at the
extreme of the environmentally realistic range that would
cause worm* case system responses*
The system models of
Figu
d 6 were analyzed subject to these worst case
assu
linear* first-order ordinary differential
equa
assumed to be a reasonable mathematical appro
ximation of the dynamic behavior of vinyl chloride in the
hypothesized structures* 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
perturbation*
9
COLORITE 01*7202
INPUT
<*<*! with worst CM* chnlcal and li*l traaslormtlon rautlon rataii
n COLORITE 017203
The systea dUgrana of Plguraa 4 through 6 t ho rotor* woro directly tranalatad to a sat of aquation* that can bo written in vector fora aa
dX AX + BU dt
Cl)
where the x^ represent the variabie quantities stored in the boxes; the a^ represent the rate coefficients for transfer from box J to box i; and the u^ represent the inputs to box
The typical or aaaple lake is assused to be 10+ a* and 10 a deep. It has a residence tine of 10 days and stratifie* in auaaer with a aetalianion 0.5 a wide centered at a S-aeter depth. It is coapletely aixed above and below the theraocline when stratified and coapletely aixed otherwise* The typical or saaple streaa paraasters were derived froa Tslvoglou and Vallace's (5) data on the Chattahoochee and Jackson rivers.
For the beat estiaate nodal* equation (1) reduces to
dx ___ 1 dt
*
a
x +u **
(2)
ficient valuet atof the beat estiaate aodel a bulk gas exchange coefficient between water of 0.43b day-* (6V Section VII of this Input was set at 1 as l"1 vinyl chloride in tsr as a reference value.
The saw exchange coefficient* st,2* in the best estiaate streaa aodel is 0*96 day"1 (5* Section VI of this report)* and the input is again 1 ng l**1 vinyl chloride.
13
COLORITE 017204
Table 1. TOAST CASB MODEL PARAHSTBKS
Svtmbol ** ,* 3,2 u,
*,2 6,2 T,4
Inttfictlon*
Volatilization of vinyl chloride
Chanical and biological degradation
Chemical and biological degradation
Transport across thermocline
Transport across thernocline
Uptake by filter feeding organisms
Uptake by filter feeding
VaIua f1 0.436
0.115 0.115
0.0178 0.0178 0.000292
0.0002S2
6, S
Uptake by benthic organisms
**, 6 i , 7 *, 6
Uptake by predator
10,61 lO,? lO,61 >10,9
Uptake by omnivore
>S,t< *6,7 5,6* S,6
a5,*
Turnover rate of organisms Water to sediment transport
Sediment to water transport
Loss from compartment
Input to water
____'ll_______--
Input to water
0.000292 9.73 <10~)
7.3 110~*)
0.1
0.107 (10"*) 3.45 C10"4)
t "J 1 ppm * ______________
15
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-------- Vinyl Chloride in Water ------ Vinyl Chloride in Air
VINYL CHLORIDE, mg/I
Figure!
iaultIon with best esti ts soctel.
17
COLORXTE 017206
Vinyl Chloride in Water ---------- Vinyl Chloride
Degradation Products
19 COLORXTE 017207
VINYL CHLORIDE, mg/I
----------------- Vinyl Chloride in Epilimnion -------------- Vinyl Chloride Degradation
Products in Epilimnion ------ ' Vinyl Chloride in Sediments
TIME, days
Stntillad lake simulation of tho modal In FI gut** 6*
21
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--------------- Vinyl Chloride in Filt r Feeding Organisms (Hypolimnion)
-------------- Vinyl Chloride in Predator Organisms
-------------- Vinyl Chloride in Omnivorous Organisms
VIMYL CHLORIDExlG, mg/ |
25 TIME, days
50
Figure 13.
Stratified lake Figure 6*
ion of the eodel In
23
COIiORlTE 017209
A dlKgnoatlc Input conslatlag of a pula* of vlajrl chlo-
rida con produc* a charactariatlc raapana* for aach coapon-
ent.
This raaponaa in a vary couciaa way of daaonatratlng
tho behavior pradictad by tho ayton hypothaaia. Tho total
raaponaa to a pula* input containa all tha infornation
nacaaaary to charactariza tha ayatan (10)*
PIauraa IS
through 17 show tha coopooant raaponaaa to a pulaa Input of
1 ng l~1 vinyl chlorlda to tha apilianion watara for tha
nodal of Pigtura 6* Xn Pigura 18* tha baginniog of tha alow
loaa of vinyl chlorida fron tha aadiaanta can ba aaan aft r
about 60 daya
Tha raaulta of a pulaa input of 1 mg l~l vinyl chlorida
to tha aadimanta ara ahown in Figuraa 19 through 21*
Tha
alow
but continuoua loaa of vinyl chlorida fron tha
aadinanta la avidant. Thin loaa occur* to tha air ( rata -- 7
x 10"* ng l"l day-"1 ) and to dovnstraaa watara (rata = 3.9 x
10-* ng l*1 day-1)
All of tha raaulta aaauna ataadyatat* lavala of bionaaa
conponants and particulataa and do not includa any low laval
toxic offacta or bionaanification (X*A*v aalactiva ratantion
of vinyl chlorida).
Pron tha raaulta of thaaa modal
ainulationa it appaara that vinyl chlorida ahould not ramain
in an acruatic acoayatan undar noat natural condition**
tJ-
25 COLORITE 017210
VINYL CHLORIDE x lO 6, mg/I
------------------- Vinyl Chloride in Filter Feeding Organisms (Hypolinmion)
*-- -- ---------Vinyl Chloride in Benthic Organisms
------------ ,. vinyl Chloride in Predator Organisms
- -------- Vinyl Chloride in Omnivorous Organisms
Flour* 16* Str*tlfla4 lak* aodwl'a raapona* to pula* input of Anyl chlorlda to opitlonion watar*
27
COLORITE 0172X1
VINYL CHLORIDE x 104, mg{1
Vinyl Chloride in Sediment (Extended Time Scale)
Figure 18* Stratified teka aodal'b raattonaa -to puls* input f vinyl chloride -to epllianlon enter*
29 COLORXTE 017212
--------------- Vinyl Chloride in Hypolimnion Water
-- -- -- -- Vinyl Chloride in Benthic Organisms
-------------- Vinyl Chloride in Filter Feeding Organisms (Hypolimnion)
Figure 20*
StratlflMt laka Model's response -to puls* input of vinyl chloride to sediMente*
V
31
COLORITE 017213
SECTION IV CHBMICAL INTERACTIONS
No pafaranc* to atudiaa of tha dagr<tatlon of vinyl
cblofida
In water could bo found in tba lltaratura*
Eovaaar, conaldarabla data ara available conctrolng tho
cbaalatry of vinyl chloride and related coapounde that can
bo extrapolated to reaction conditions anticipated in tho
environment*
Bvidonco supporting such extrapolations van
obtained in a few preliminary experiments*
Pour pathways were postulated as potential mechanisms
for chemical degradation or alteration of vinyl chloride in
the environment:
substitution (ID* elimination
(12)t
addition (13)* and oxidation (14)*
In nucleophilic substitution* the chlorido ion is
displaced by a nucleophilic species (Nu) (11)*
Reactive
nucleophiles
common to the aquatic environment are amin s
thiols* water* and hydroxide ion*
The reaction can be
either first or second order depending on the specific
mechanism*
The most
probable
elimination
reaction
in the
environment is one in which hydrogen chloride is eliminated
from vinyl chloride in the presence of base* producing
acetylene (13)*
This is a second--order reaction and the
rate is dependent upon the concentrations of both vinyl
chloride and base*
The most significant base present in
natural water would be hydroxide ionS
HH NC = cy
>. H
\ Cl
Base
HC=CH + Cl~
Th#wMition 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
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SEPTUM
||jur 22*
.
Vinyl chlorld reaction vassal*
35
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Table 2.
ORDER OP MAGNITUDE ESTIMATES FOR HALF--LIVES FOR VINYL CHLORIDE REACTIONS
J,
React^^
_________Li teratu re data
Temp*
Haxlmum rate
Estimated t,
.. | 11
]
l C)
Reactant
constant ll"* sec"1
25C8
I
Elimination3 95.53 Hethoxide
10-?
<10 yr
(--o 1 #
Substitution^ 130
C2HsS~
<10 yr
i
Addition0 25 h2o
10"*
<1 yr
Add!tlond 25 Cl 2
10"*
140 hr
i
Addition6 25 HOCl
10"3
1000 hr
1*4
gEdcnlyaiaf___ 1ZQ_____ -HaQ_________ ________ Hfl Bi________ --------- 1Q yr______
^Reference DReference
thiol ^Reference
17* 18*
19*
methanol solvent* 1Q""3H asthoxlde. reaction of 1--chloropropene In ethanol at
acid catalyzed hydration at pH 3*
1x
10"3H
Reference 20* 1 * 3*3--trlchloropropene In aqueous acetic acid--------1 ag l_l j chlorine
cReference 21* hypohaloua acid addition to ally! alcohol at pH 4*5-------
I as l~1 hypohaloua acid* `Reference 15* ^Calculated assuming pseudo first-order kinetics*
COLORITE 017216
I I
A 8ur*y of tho lltratur did not diacloa* any aqullibriua
constanta for tho foraation of coortflnata coaplnxaa batman
vinyl chloride and natal Iona*
However, data for tho
toraatlon of coaploxoa botsoen structurally rolatod olofinic
compounds and As* and Cu+ (Tahlo 3) indicato that electron--
withdrawing groups attached to tho double-bonded carbon atom
of the olefin decrease the equilibrium constant* Assuming a
concentration of 10 mg l~1 for the silver-ethylene complex,
equilibrium calculations shov the complex to be greater than
99%
dissociated*
Similarly, the cuprous--0--ehloro--allyl
alcohol complex at 6*2 mg l--1 is also greater than 99%
dissociated*
The effect of other ligands common to the
aquatic environment, vhich would be competing for the metal
ions, are neglected in these calculations* Thus we conclude
that at low metal ion and vinyl chloride ion concentrations,
cosplexatlon by these metal ions is not important*
t
j
i
39 COLOR!TE 017217
SECTION V PHOTOCHEMICAL INTERACTIONS
Several poaslble mechanises exist for the decomposition
of vinyl chloride by light (Figure 23)* Mechanism If direct
photolysisf 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 am) (20* 27f 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 reactiont may also occur*
Mechanism
II,
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 Ml al* (29)* for example* Indicated that photolysis
of vinyl chloride can be sensitized In the vapor phase by
mercury atoms* The authors concluded that in this case* the
primary photochemical process for triplet VCM in the vapor
phase involved elimination of molecular HCl*
However*
homolysis of the carbon--chlorine bond could not be ruled out
by their data*
In solution* the major photoreaction for
triplet chlorinated olefins was found to involve twisting
around the double bond (30)*
Mechanism III* which we have called chemical sensitization* Involves direct chemical reaction between sensitizer and olefin* Such reactions are known to occur in the condensed phase with simple olefins and electronically excited ketones (31).
MooiiBjmlsm
IV*
free
radical
decomposition
and
po1vmesjfipmtlon of VCM Initiated by photochemical homolysis
of a sgmxies like a peroxide* is also a possible pathway* Example!?-h* the light-initiated polymerization of vinyl
monomers are discussed by Walling (32)* Uri and co--workers
found
that
polymerization
of vinyl monomers can be
"photosensitized1* by chlorophyll (33) and by iron complexes
(34* 35)*
The "photosensitizatlon" in these cases clearly
did not Involve energy transfer* but rather the generation
of free radicals followed by polymerization (Mechanism IV)*
41
COLORITE 017218
The photodagradation of vinyl chloride m studied to determine whether the shove processes ere possible in the agu*tic environment* and whether their rates* If they occur* are sufficiently high to compete with other processes*
MATERIALS AND METHODS
Vinyl chloride gas from Mattieson Company was used
without further purification*
Laboratory distilled water
was redistilled from basic permanganate immediately prior to
use*
Natural waters were obtained from the Oconee River in Athens* Georgia* and the Okefenokee Swamp (Big Vater Lake) in South Georgia* Commercial humic acid was obtained from Aldrich Chemical Company*
Stock solutions of vinyl chloride were prepared in small
bombs equipped with gas-tight Teflon stopcocks*
Aliquant*
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 CCl
Aqueous solutions were
prepared
following
the
same
procedures; the concentration in water was then measured
exactly by comparison to the CCl stock solutions* Analyses
for VCM were performed by gas--liquid chromatography on a 2 m
x 0*32 cm glass column packed with 0*49 Carbowax 1500 on
Carbopack A*
The column was cured by heating at 200C for
48 hours with slow purging by nitrogen*
Glc 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 stopcock.
All
photolMMfMjt studies were carried out in reaction ceils
equipSMH&Vlth
gas-tight
Teflon
stopcocks*
Controls
estabeglpplMf that no leakage of VCM occurred from these cells
over s pmrlod of at least two weeks*
Kinetic studies were generally carried out at VCM
concentrations of 10 to 20 mg l-1*
The light from the
mercury lamp was filtered through a 3 mm-thlck Pyrex sleeve
(cutoff at 300 nm) for most of the studies* Singlet oxyg n
43
COLORITE 017219
Iartifact P hnt olvnl
Although dlroct photolysis (Hochaniaa I) is lMoosurably
alow,
ths literature indlcatoo that ths light-*induce<t
tranatoroatloaB of vinyl chlorido could occur
through
indirect
pathways
( llachanisss
II--IV).
For example,
substances found dissolved In certain natural eaters war
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 10 2 M VCM) van 0*75. A colorless precipitate formed
during photolysis, but it was not identified.
Since the major photochemical process for triplet 1*2--
dlchloroethylene
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 oxetanea is not
particularly efficient. Therefore the high disappearance
quantum yield for the acetone--sens!tized photolysis of VCM
was surprising*
The photolysis may Involve inefficient
hoaolyaia of the carbon--chlorine bond of triplet VCM.
followed by free--radical polymerization of VCM. l.e.. most
of the VCM would be consumed by secondary thermal reactions.
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
state energy of the sensitizer equals or exceeds
the acceptor, l.e.. VCM. Since the triplet state enerfljHV'of mono--olefins are very high ( 78--82 kcal mole 1 )
OSlgnPgmlv high energy sensitizers such as acetone (triplet
energy 80 kcal mole"1 ) are effective. Unfortunately, little is known about the concentrations and distribution of highenergy 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 environment.
45
COLORITE 017220
100
TIME, hrs
FIbuv*- 24* D*coooaltion ol vinyl chlorld* In vatr by mykkmu ol lr radicals ganaratad by photolysis (300 ns) of hydroan paroxlda* 47
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SCREW CAP
HOLE
RUBBER SEPTUM TEFLON FILM LINER
Apparatus lor vinyl chloric!* degradation and toxicity studies.
49
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aedlum containing 6*0 g glucona par liter* Kadlum a dacantad and enough fungi vara traneierrad to 5--ml graduated centrifuge tubas with ground glass stoppers to give approximately 5 g dry weight of fungi par liter of water*
Chlorella nvrenoldoee was grown in Benaen-Puller aediua
containing 0*1% Hutner'e traca
elaaant
solution
and
incubated on a shaker at 15C under 170 ft~c of continuous
light* Cultures wsra centrifuged, waahed three times* and
transferred to 5--ml graduated centrifuge tubes with ground
glass stoppers for sorption studios to give approximately 4
g dry weight of algae per liter of water* To eliminate
correction! for wolatilization of VCH to tho air above the
solution* tubss wsro filled to the top and all data ware
compared with data from control tubem (containing no
organisms)
To determine dry weight* of algso and bactoria used in
sorption studios* . .cultures were
centrifuged
and
the
organisms were washed three times*
The organisms were
quantitatiwsly transferred to tared beakers and dried to a
constant weight at 90C*
Fungi ware separated from tost
cultures for dry weight determinations by filtering* first
through tared pre--filters* then through tend 0*22 micron
Nucleopore filters* and by drying to a constant weight at
90C.
ttBSULTS AND DISCUSSION
Sorotion of Vlnvl Chloride to Microorganisms
In systems in which sorption is linear I wary low solute concentrations), the simple distribution coofflcient (K^) nay be used to describe the extent of sorption of a compound to microorganisms
(3)
where cg
concentration (mg/mg) of solute in solution at equilibrium
51
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containing only baaal aalta and 54 ag l ~1 VCM aithou* an
additional carbon sourcta
Ttiaao culturt* vara aoni torad
daily for ona week* No dagradatlon vaa detectad at any tine
in any of t-he cultures*
Byington
and
Liebman
(43)
have
shown
that
trichloroethylene was transformed to chloral hydrate by rat*
rabbit* and dog liver aicrosoaea in a reaction requiring
NADPH and oxygen* Baaed on the structures of the compounds
and the requireaent of NADPH* alcohol dehydrogenase say be
the active enzyae*
If so* degradation of VCM by bacteria
could be possible via the following pathway:
HH \/ C=C /\
H Cl
HH
II
H-C-C-Cl
V/
0
Alcohol Dehydrogenase,,
NADPH, H+
HH
II
H-C -- C-OH
II
Cl OH
H0
I II
H-C-C-H
I
Cl
If the bacteria were capable of degrading VCM by this
pathway* a systea in which oxygen was not a Uniting factor
would be needed* The closed flask systeas described earlier
could limit the oxygen in the systea* 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 aonitored for possible
products by glc analysis at low coluan teaperature using
FID*
No degradation products were detected in any of the
cultures*
ToXlcl-tv of Vinvl Chloride to Bacteria
The toxicity of VCM to five actively growing bacterial
populations vaa tested*
Testing could not be done at VCM
concentrtUttt up to its solubility in water ( 1700 ng l 1 )
becauae-iH: the difficulty in supplying the bacteria with BUlllclMBSsyien for growth above a VCM concentration of
900 ag SW,
Because even at 900 mg l~1 VCM the oxygen
concentraflaa 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
oxygen*
No difference could be detected
between bacterial growth In cultures and In teat cultures
containing up to 900 ag l**1 VCM* The VCM was therefore not
toxic to bacteria at these concentrations*
S3
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r&t*
of oxygen redtrat ion to ellnlnata tho nood for
ddiuronont of turbulance and to nlato vinyl chloride
volatilization to avallabla onvlronaontal dataralnatlona of
oxygen raaaratlon*
For coaparlaont tho ratio of specific rotes calculated using estimates of molecular diameter*
was
also
MATERIALS AND METHODS
Nltrogen-spargod, deionized water (900 mil 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 cm* 5 cm* and 10 cm* respectively*
Oxysen
and vinyl chloride concentrations were measured every 10
minutes for 180 minutes using a dissolved--oxygen meter and a
Mas chromatograph. Six replications of these experiments were performed*
BBSULTS AMD DISCUSSION
The
mss
represented as
the equation
exchanM* dynamics at the interface - were a first-order approach to equilibrium uainM
dc
dt
K(CS-C)
(6)
where
<S%4 as
trr *
*-
ca =
Mas concentration time specific rate saturation concentration
The concentrations of oxyMn 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 loM*rithmic form of the solution to equation 6* The corrected suns of squares for all beakers stirred alike were pooled to
55
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t FiffUi
a* four mixing level 58
'i J
COLOR!TE 017226
specific rate of exchange of vinyl chloride water and air is about tvice that of oxygen.
flan
batwMn
59 COLORITE 017227
10
lirtaa H. R* and D. B.
Thoory. Coluabu** Ohio,
I960- 611p.
Allan* Charloo
Introduction -to Syntonn B. Morrill Books, Inc,
12. Giorgio Modnnn* Account* Chon, Boo* i:73, 1971*
12*
Cockorlll* A* p. in; Co*pr*hon*iro Choaleal Kinotlca, Volua* 9, Bnnford, C* H* nnd C* P* H* Tlppor (ado*).
York, Aaorlean Blaovlor Scientific PublUhlng Co., Inc*, 1973* p* 163*
13.
Bolton, R. In: Conprohonolvo Chemical 1notlea, Yoluno 9, Bnnford, C. H. and C. P* H. Tippor (eda). How York, Anorican Blaerier Scientific Publlahing Co*, Inc., 1973* p. 1
14. Vailing, C. Proo Radical* in Solution. Wiley and Son*, Inc., 1957. p. 397
Now York,
John
IS. Rappoport, Z. and A. Cal* 1969.
J. An. Chan.
Soc*
91:5246.
16. Kalinin, A. I., B. M. Poroplotohlkowa, I. A* lorsttuno,, and B. N. Zil'baraan. Zh* Oboheh. Khia. 36:1563. 1966* C. A. 66:61277C.
17. Millar, S. I. J. Or. Chon. 2&S2619, 1961.
18. Jonoa, D. B., B. O. Morria, C. A. Tornon, and R. F. M. Whit#* J. Chon. Soc. 2349, I960.
19. Bhornaon, S. S* Soltzar, and R. Dufforback.
Chon. Soc*
563, 196S*
J. An.
20. Shalton, J. R. and L. H. Loo* J. Ore* Chow. I960.
2$:428.
21. Iaraol, G. C., J. K. Martin, and P. G. Sopor. J. Chow. Soc. 1282, 1950*
22. Braa^|'.JR. Acta Choa . Scand* 13:1639, 1959.
AndrSppf' L. J. and R. M. Keefer. J* Aaor. Chon. 23.
3:5733, 1951.
Soc*
24. Vinatoln, S* and H. J* Lucas. 60:836. 1938.
J. Aaor. Choa. Soc.
61
COLOR1TE 01*7228
42. Payne, W. J. and V. B. Faisal. JJLJ339-344, 1963.
Appl
Microbiol.
43. Byington, K. H. and 1<3):247-254, 1965.
B. C* Lalbsan*
Mol.
C. A. 4:11457*, 1966.
Pharmacol.
44.
Dreisback, R R.
Physical Propertlas ot
Chemical
Compounds.
Advances in Chemistry Series, Numbers 15,
22, and 29.
Washington, D. C. American Chemical
Society, 1955-1961. 407p.
45. Weast, 8* C. (ed). Cleveland, Ohio, P177.
Handbook ol Chemistry and Chemical Rubber Co., 1971.
Physics. p. F173-
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