1331.pdf

A B S T R A

C

T

M

I C H E L L E S

U

S A N N E

M

C

G

I N N I S. T o xicity of

G

r o u nd

W

ate r a nd Su bs u rfa c e

S

e

d i

m

e nt

S

a

m

_{p l}

e_s

C

o

l l

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d

at a

Sit

e

C

o nta

m i

n a_{t e}

d w i

_t

h T C E U

n

d

e r

_g

o

i

n

_{g I}

n

S i

tu

M

ethano tro

_{p h i}

c

B io r e

m

e

di

a t

i

on .

(

U

n

de

r t

h

e

d i

re ct

i

on o

f D

r.

F

re

d

er

i

c

K

.

P f

a en

d

er

)

G

r_ou n

d

wate r a n

d

su

b

s u r

f

a c e s e

d

i

m

e nt sa

m p

le s c ol le cte

d

at a sit e co nta

m

i

nat e

d

w i

th tr

ic

hl

o r oet

h

_y

l

e n e

(

T C E

)

t

h

a t w a s u n

d

e r

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o

i

n

_{g i}

n s

i

tu

bi

o r e

m

e

d i

at

i

o n we re t est e

d f

o r

a c ute to x icit_{y w i}th a

b

a cte rial to x

i

c

i

t_y a s s a_{y k}n own a s

M

ic r oto x®

(

C

a rlsbad,

C

A

)

. A

r e_pres e ntat

i

v e s a

m p l

e o

f

the

_g

r o u n

d

wate r c ol

l

e c te

d

wa s te ste

d f

o r

_g

e n oto x icit

_{y w i}

th the

ne

w l y d

ev e

l

o

_p

e

d b

a cter

i

a

l

a s s a

_{y k}

n own a s

M

utato x®

(

C

ar

l

sba

d

,

C A

)

.

T

ox

i

c

i

ty

i

s a n

im

_p

o rta n t e n

d

_po

i

nt o

f b i

o r e

m

e

di

at

i

on, a s t

h

e r e

d

uc t

i

o n o

f

t ar

g

e t c o

m

po u n

d d

o e s n ot

e n s u r e safe t_y to

h

u

m

a n health a n

d

the e n viron

m

e nt.

O f

te n ti me s a

m

o r e to x

i

c o r

h

a r

m f

u

l

p

r o

d

u ct

w i l

l

b

e

f

o r

m

e

d d

u r

i

n

_g

t

h

e

b

r e ak

d

own o

f

the ta r

_g

et c o nta

m i

n a nt.

U

s

i

n

g

to x

i

c

i

t

y

a s

a n e n

d p

oin t of

b

io r e

m

e

di

atio n w

i l l

hel

_{p d}

ete ct a n

d

m

o n

i

to r

_p

ote ntial ha zar

d

s o c c u r rin_g

d

u rin

_g

the

b i

o re

m

e

d i

at

i

o n ef fo rt s.

A

c ut e t ox

i

c

it

_y

a

_{p p}

ea r e

d i

n on

l

_y two

_g

r ou n

d

wate r we

l l

s

(

out o

f 12

)

.

T h

e t ox

i

c

it

y

in o n e o

f

the

w

el ls

(

m h

t-

7

_c

)

a

_p

_pear e

d

o n

l

_y at o n e ti me

_p

oint, w h

il

e the t oxic

i

ty in t

h

e othe r

w

el ls

(

m

h

c- l

O

_c

)

p

e rsist e

d

tr a n s

i

entl y

f

o r a

b

o ut s

i

x

m

ont

h

s. Bo th o

f

t

h

e se

w

e

l l

s

w

e r e

loc a t e

d

a t the

_p

er

i p

her

_y

o

f

the tr ea t

m

ent z o n e

A

l

l

o

f

t

h

e sa

m p l

e s t

h

a_{t e}x

h i b i

_{t e}

_d

_to x

i

c

it

_y

had a v e r_{y h}

i gh p H

₍

a

b

o v e 1

0

)

.

G

e n oto xicit

y wa s

_p

r e s e nt in the

_g

r o u n

d

w ate r s a

m

_p

led

fr

o

m

a

l l

o

f

t

he

we

l l

s.

T h

e c o

m p

o un

d

c a u sin

g

t

h

e

g

e n otox

i

c

it

y

s e e

m

e

d

to

b

e

p

re s ent

in

the

w

a te r

i

n an a c tive

f

o r

m

as

m

o r e sa

m p l

e s c a

m

e u

_{p p}

o s

it

i

v e w

h

e n te s_te

d i

n _the a

b

s e n c e o

f S

-9

₍

r at

l i

v e r

h

o

m

o

_g

e na t e

₎

tha n

i

n the

_p

resenc e o

f S

-

9

S

ed i

m

e nt s a

m p

le s we r e

m

o r e to xic

i

n the c o nta

m

in ated z o n e, de

p

ths

g

r e ate r tha n

1

0 0 f

e et

₍

3 0

.

5

m

et er s

)

, tha n

i

n the u n c o nta

m i

n ate

d

z o n e,

d

epths le s s tha n 1

0 0 f

e et

(

3 0

.

5

m

ete r s

₎

. A U of the to x

i

c s e

d

i

m

e n ts t

h

a t e xh i

b

ite

d

to xicity si

g

ni f ica nt

l

y a

b

ov e the contr ol

s e

d i m

ent s were c

la

_y

s e

di m

e nts.

I

t wa s n ot

p

o s s

i b l

e to

d

ete r

m i

ne s

i g

n

i f i

c a nt c

h

an

g

e s

i

n the

tox

i

c

i

t_y o ver

ti

m

e

_p

a r

ti

a

l l y b

e c a u se o

f

the w

i de

c o n

fi d

e n c e inte r v als of t

he

d

ata. B asic al

l

y,

n o cha n_ge s in to xicit_y

i

n the s ed i

m

e nt s a

m

_{p l}e s we r e s e e n

d

uri n_g the c o u r s e of the

I V

A C K N O

W

L E

D

G

M

E N

T

S

T he r e a r e

m

a n_y

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w

ho

I

wo u

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iz e

f

o r t

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tr

i b

ut

io n s

to

m

_y

r e s e a r c h a s

w

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m

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to

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r. Fr e

d

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ri

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f

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fo r al l the o

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U N C

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s o,

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to t

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r.

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Dr. B a r

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a

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y b

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Sa r r

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a z e n, the d ir e c to r of th

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Sa v a n n a

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L

IN T R O D U C T

I

O N

1

I L

L

I

T E R

A

T

U

R

E

R

E

V

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W

6

A .

H

ealth E

f f

e cts o

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T

CE

6

B

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r o u n

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e

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at

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1.

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8

2

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A

r o

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12

3

.

M

etha n e o x i d iz e r s 15

4.

O

the r o xi

d

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D.

T

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i

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A

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y

s

2 0

m

.

M

A T

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R

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A L S A

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2 3

A

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m

o n str at

i

on

p

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d

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i

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2 3

B .

M

i

c r oto x

®

_{2 9}

1.

100 % A

s s a

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30

2

.

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l

i d P

ha s e A s s ay

32

C

.

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u tat ox

®

_{3 5}

I V

.

R E S U L

T

S A N D D I S C U S SI

O

N

3 9

A

.

G

r o u n

d

wate r s a

m p

le s

~

_M

_{ic r}

_{o t ox}®

_{3 9}

B .

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rou n

d

w at er s a

m

p

le s - -

M

ut a t ox®

5 1

C

.

Se

d i

m

ent sa

m p

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--

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i_{c ro t ox}®

5 5

V

.

C O N C L U SI

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6 8

V L

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V

n .

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S

7

5

A

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M

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to x

®

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_I

n

d

e x v a

l

u e s —

W

ate r sa

m p l

e s 7

5

B.

M

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v alu e s --

Wa

t_{e r s a}

m

p

le s

8

7

C

.

M

ic r oto x

® _E

_{C 5 0}

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n

d

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Se

d i

m

L I S T O F F I G U R

E

S

F i gu r e 1. 1 L o c atio n of the

Sa v a n n a

h R iv e r

S

ite

(

S

R

S

)

3

F

_{i g}

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2

.

1

R

e

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i

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y

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a n o

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10

F i g

u r e

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.

2

T

o

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p

at

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way o

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P put

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a n

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13

F

_{i g}

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2

.

3

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p

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4 1

3

F

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.

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T

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.

5

Po ss

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p

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s of T

C

E degr adat

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F i g

u r e

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.

1

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R

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2 7

F i g

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.

3

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v

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le c

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2 8

F i

_g

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3

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S

che

m

atic o

f

the

M

ic r o

to x 1

0 0 % A

s s ay d

i

lut

io n

s e r

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3 1

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3

.

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h

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m

at

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the

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3

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6

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3 4

F

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.

7

M

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3 8

F i g

u

re

4

.

1

T o x

ic

i

ty o

f g

r o u n

d

wate r s a

m p

le s c ol le cte

d d

u r

i

n

g

the

1%

a n

d

4

%

m

etha n e

in

j

e ct

i

o n ca

m

_pa

i g

n s 4

0

F i g

u

re 4

.

2

T

ox

i

c

i

t

y

o

f g

rou n

d

w a t er s am

p l

e s c o

l l

e cte

d d

u r

in

g

the

p

u

l

s

in

g

a n

d

n ut

ri

e nt

i

n

j

e c t

i

o n c a

m p

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n s a n

d

a

f

te r s

h

ut

d

own

4 1

F

_{i g}

u re

4

.

3

p H

o

f g

r o u n

d

wa t er c ol le c t e

d fr

o

m

we

l l m

ht

-

1O

_{c ov e r t}

i m

F

i

_gu r e 4.

4

T o xic

i

ty o

f

gr o u n

d

wate r c ol le cte

d f

r o

m

we

l l m

ht

- 10 c at t

h

e

a

m b

ie n t _p

H

a nd w ith the _{p H} a

d

_j

u ste

d

to betwe e n s

i

x a nd ei g ht 4 4

F i

_g

u r e 4.

5

p

H o

f

gr o u n

d

wate r c ol le c te

d

fr o

m

wel l

m

ht

-7

c o v e r ti

m

e 4

5

F

i

_gu r e

4

.

6

To x

i

c

it

y o

f

gr o u n

d

wate r c olle c te

d f

r o

m

we

l

l

m

ht

-

7

_{c at t}

h

_e

a

m

b

ie nt _{p H} a nd w ith the

_p

H ad

_j

u ste

d

to

b

etwe e n s

i

x a n

d

ei g ht

4 6

F

_{i g}

u re

4

.

7

Tox

i

c

it

y

an

d

T

C E

c onc entr at

i

o n s

i

n

g

r o u n

d

w at er co

l l

e cte

d

fr

o

m m

ht-

l O

c o v e r t

im

e

4 8

F i

_g

u r e

4

.

8

To xic

i

ty a n

d p

e r c e nt ba cte ria in

g

r o u n

d

w ate r c ol le cted fr o

m

m

ht- l

O

_{c o v e r} ti

m

_e 4

9

F i g

u r e

4

.

9

T

o x

i

c

i

ty a n

d p

erce nt

m

et

h

a n e

i

n

g

rou n

d

wate r c o

l l

e cte

d f

ro

m

m h

t-

l O

c o ver ti me

5 0

F i gu r e

4

. 10

G

e n oto x

i

c r e spo n s e s o

f g

r o u n

d

wate r,

i

n

b

u

f

fe r

m

e

d

iu

m

,

c ol

l

e cte

d

a t the sta rt a n

d

at the

fi

n

i

s

h

o

f

the

i

n situ

b

io r e

m

e

d

iatio n

d

e

m

o n str at

i

on at the

S

a v a n na

h R i

ver

Sit

e

5 2

F

_{i g}

u r e

4

.1 1

G

e n oto x

i

c r e s

p

o n s e s o

f g

r o u n

d w

ate r

,

i

n

b

u

f

fr

m

e

d

iu

m

w

ith

S

-

9

, c ol le cte

d

a t t

h

e sta r t a n

d

at the

fi

nis

h

o

f

the

i

n s

i

tu

b i

o r e

m

e

di

at

i

o n

d

e

m

o n str at

i

o n at the

S

a v a n n a

h

R

i

v e r

S i

t e

5 2

F i g

u r e

4

.1

2

G

e no t ox

i

c re s

p

o n s es o

f

re

p

re se ntative

g

r o u n

d

wate r sa

m

p

les

in

b

uf fe r

m

e

di

u

m

c ol le cte

d

afte r the c o

m p

le t

i

on o

f

e a ch

in

j

e ctio n c a

m

_pai gn

_{5 3}

F i g

u r e

4

.

1 3

G

e n oto x

i

c r e s

p

o n s e s o

f

re

p

re s entat

i

ve

g

r o u n

d

wate r s a

m

p l

e s

i

n

b

u

ff

er

m

e

d i

u

m

w

i

t

h S

-

9

c o

l l

e cte

d

a

f

te r t

h

e c o

m p l

etio n o

f

e a c

h

i

n

j

e ct

i

o n ca

_{m p}

a

i g

n

5 3

F

_{i g}

u r e

4

.

14

G

e n oto x

i

c r e spo n s e s o

f

gr o u n

d

wate r s a

m

p

les c ol le cte

d

fr o

m

m h

t-

l Oc

i

n

b

_u

f f

e_r

m

_e

d i

_u

m

_{o v e r} t

i

m

e

5 4

F i

_g

u r e 4.1

5

G

e n oto x ic r e spo n s e s of

g

r o u nd w ate r s a

m

p le s c ol le cted fr o

m

m

ht- l

O

c in

b

uf fe r

m d i

u

m

w

it

h S

-

9

_{o v e r} ti m_e

5 4

F

_{i g}

u r e

4

.

16

T o x

i

c

i

t

y

o

f

s e

di m

e nts c o

l l

e cte

d f

r o

m C l

us te r

1

5 8

F i g

u r e

4

.

17

T

ox

ic

i

t y o

f

s e

di m

e nts c o

l l

e cte

d fi

V U l

F i gu r e 4. 1 8 To xicity of s ed i

m

e nts c ol le cted fr o

m

C lu ste r 3 6 0

F

i

_gu r e 4. 1

9

To x

i

city o

f

s ed

i m

e nts c ol le cte

d f

r o

m C l

u ste r 4

6

1

F i gu r e 4.2

0

To xicity of s e

d

i

m

e nts c ol le cte

d

fr o

m m

hc

-9 6 2

F i g

u r e

4

.

2 1

T

o x

i

c

i

ty o

f

s e

d i m

e nts c ol

l

e cte

d fr

o

m m

hc

-

1 1

6 3

F i gu r e 4.2 2 To xicity of s ed i

m

e nts c ol le cted fr o

m m

hc

- 1 2

6

4

F

i

_gu r e 4.

2 3

To x

i

c

i

ty o

f

s e

d i m

e nts c o

l l

e cte

d

fr o

m m

hc

L

I ST O

F

T A

B

L E S

Tab le

3

. 1 In

j

e ct

i

o n c a

m p

a

i g

n s te st e

d d

u

ri

ng t

h

e

i

n s

i

tu

b i

o r e

m

e

d i

at

i

o n

de

m

o n str atio n at the Sa v a n n ah R iv e r

Si

te . 2

5

T

a

b l

e

3

.

2

C l

u ste r s o

f b

o r e

h

ole s co

l l

e cte

d

at t

h

e

S

a v a n na

h R i

v e r

Si

t e

2 9

T a

b

le 4. 1 E

C 5 0

o

f

po s si b

l

e

m

et

h

a n otr o

p

h ic

m

etabo

li

te s o

f

T

C

E a s

d

ete r

m

in e

d

b

_y

M

ic r oto x 4

7

T

a

b l

e

4

.

2

E C 50 I

n

d

e xe s an

d 9 5 %

u

p p

er an

d l

ow er co n

f i d

enc e

i

nter va

l

s

o

f

s e

di

m

e nts t

h

a_{t w}e r e s

i g

n

i f i

c a nt

l

_y

di f f

er e nt t

h

a n t

h

e c o ntr o

l

a v e r a

_g

e ..

5 7

Tab le 4.

3

Si

gni fi c a nt d i f fe r e n c e s betwe e n clay s e

d

i

m

e nts w

i

th in a clu ste r

6 6

T

a

b l

e 4.

4

Si g

n

i fi

c a nt

d i f f

e r e n c e s

b

etwe e n c

l

ay a n

d

s a n

d

s e

d i

m

e nts w

i

t

hi

n

I

.

I N

T R

O

D

U C

T I

O N

G

r e at c o n c e r n

h

a s

d

ev e

lo

_p

e

d

a s the

_p

r e v a

l

e n ce o

f g

r o u n

d

wate r c o nta

m

i

n at

io n

h

a s

b

e en re c o

_g

n

iz

e

d

.

I

m

p

ro

p

e r

d i

s

p

o s al, s

p i l l

s,

l

ea

k y p i p

e s, an

d

u nc on

f in

e

d l

an

d fi l l

s

h

ave

l

e

d

to w i

d

e s_pr e a

d

che

m

ic al c o nta

m i

n at

i

o n o

f g

r o u n

d

w ate r a n

d

the s u

b

s u rfa c e.

Tr

i

c

h lo r

o e t

h y l

en e

(

T

C E

₎

is o n e o

f

the

m

o st c o

m

m

o n c

h

e

m i

c a

l

c o nta

m

in a n

ts

f

o u n

d i

n

g

rou n

d

w ate r

(W

est er

i

c

k

,

19 8 4

)

. It

is

a so

l

v e nt an

d d

e

g

rea s e r w

i d

e

l

y u s e

d i

n t

h

e

m

e t a

l

s ,

e

l

ectron

i

c s, an

d dr

y c

le

an

in

g i

n

d

us tr

i

es. T

CE

is

the

m

o st

f

r e

q

u e n tl y re

p

ort e

d

conta

m i

n a nt

at s

i

t e s on t

h

e

N

at

io

n a

l

Pr

i

or

it

_y

L

i

st

₍

N

P

L

₎

an

_{d i}

_{s a}n

E

nv

i

r o n

m

e nta

l P

r o_te_ct

i

_on

A g

enc

_y

(

E P A

₎

_p

r

io r

i

t

_{y p}

o

l l

u_tant

(

U S E

P

A

,

19 85

)

.

Hu

m

an s c o

m

e

in

to co nta ct w

i

th T

CE w h

en the

ir

_g

r o u n

d w

ate r s u_{p p}

Ue s

b

e c o

m

e

c o nta

m i

n ate

d

. Ex

p

o s u r e to T

C

E c a n oc c u r thr o u

g

h in

g

e stio n

,

i

n

h

alatio n, a n

d d

e r

m

al a

b

s or

_p

tio n.

E

x

p

o s u re

b y i

n

g

e st

i

o n o c c u r s

b

y c o n s u

m i

n

g

c o nta

m

i

n ate

d w

ate r.

E

x

p

o s u r e b y

d

e r

m

al abs o r

_p

t

io n

o c c u rs b y wa sh in

_g

o r

b

athin

_g

in c o nta

m i

n ate

d

wate r. In

h

alatio n o

f

T C E

o c cur s

b

e c aus e

T C E i

s a v_o

l

_{a t}

i l

_{e c o}

m p

_ou n

d

an

d

e a si l_y

_p

art

i

tion s

fr

o

m

t

h

e wa t er

p h

a s e t o t

h

e a

ir

_{p h}

a s e w

h

en wa t er

i

_sr u n

f

ro

m

a ta

_p

o r show er.

B

o th a cute an

d

c

h

ron

i

c he alth ef fe cts r e s ultin _{g f}r o

m

e x_po s u r e to T

C

E ha v e be e n do c u

m

e nted

(

A T

SD R

, 1

9 8

9

)

.

T he ne e

d

t o r e

m

o v e T

CE

fr

o

m g

r ou n

d

wate r su

_{p p}

l

i

e s

is u r

_g

e nt. In a

d d i

t

io n

to t

h

e

h

e a

lt

h ri

s

k

s a s s oc

i

a te

d

w

i

t

h T C E

ex_po s u r e,

T C E

c a n

b

e

b i

o

l

o

g i

c a

l l

y tr a n s

f

o r

m

e

d

to v

in

y l

ch

l

ori de u nde r a n a e r ob ic c o nd itio n s. V iny lch lori

d

e

, a kn own c a r cin oge n , pr e s e nts

m

u ch

m

o r e

ri

sk t o hu

m

an

h

_ea

l

th t

h

an

T C

E

i

t s e

l f

.

Id

ea

l l y

, a

l l

t

h

e

T C E p

re s ent

l y i

n the

g

r ou n

d

w

ater shou

l d b

e re

m

ove

d

,

b y

e

i

ther

p hy

s

i

c a

l

, c

h

e

m i

c a

l

, o r

b io

l

o

g i

c a

l

te c

h

n o

lo

g i

e s,

how e v e r, this is u nl i kel y. P

ri

ori ty sho ul

d

be g iv e n to site s w he r e

trans

_p

o rt o

f

T

C E

t

h

r o u

_{g h}

o ut t

h

e su

b

su r

f

c e. T h

E

P A h s t a

M

C

L

(

m

a

i

m

m

c o nta

m

in a nt le v el

)

of T

C

E in

d

r

i

nk in

_g

w ate r of

5

_{p g}

/

L

_{(p p b}

₎

. Va rio u s te chn olog

i

e s a r e bein_g te sted fo r their eco n o

m

ic a nd te chnic al fe a si

b

i l it_y, a s wel l a s the degr e e to w h ich

the_y cle a n u

_p

the c o nta

m

in ate

d

site.

O

n e te chn olo

gy

that hol ds

p

r o

m

is e is in s

i

tu

b i

ore

m

e

d i

a t

i

o n.

A

n exte n s

i

v e

i

n s

i

tu

b i

o r e

m

e

di

at

i

o n

d

e

m

o n str at

i

o n

h

a s

j

u st

b

e e n c o

m

_{p l}

ete

d

at the

S

avan n ah R

i

v e r

Si

t e

(

SR S

)

. T he a

b i

l

i

ty o

f m

et

h

a n otro

p h i

c

b

a cte r

i

a to

d

e

g

ra

d

e T

C

E

h

a s

b

een s

h

ow n

i

n

m

a n_y

l

a

b

o r ato r_y e x

_p

e r

i m

e nts.

A f

te r e x a

m i

n

i

n

g

t

h

e s u

b

s u r

f

a c e,

g

e o

l

o

g

y,

c

h

e

m i

str_y, a n

d b i

o

l

o

g

y a t t

h

e

S

R

S

,

i

t w a s

d

e c

i d

e

d

t

h

at

m

et

h

ano tr o

p h i

c

b i

o r e

m

e

d i

at

i

o n w as

l i k

e

l

_y to

b

e e

f f

ect

i

ve.

T he

S

a v a n n ah

R i

v e r

S

ite

(

S

R

S

)

is a

3

2

0

s

_q

u a r e

m i l

e

(

2 5 9 0

s

_q

u a r e k

i

lo

m

ete r

)

fa c i l it_y o

w

n e

d b

_y t

h

e D e

_p

a rt

m

e nt o

f

En e r_{g y} a n

d

o

_p

e r ate

d b

_y the

W

e stin _{g h}o u s e

S

a v a n n ah

R

i

v e r

C

o

m p

a n_y .

T h

e

f

a c

i l i

t

y i

s

l

o c ate

d

n e a r

A ik

e n

S

.

C

.

(

F i g

u re

1

.

1

)

a n

d h

a s

b

e e n

i

n v o

l

v e

d i

n n ucle a r

_p

r_o

_d

u ct

i

o n s

i

n c e 1

9 50

.

F

ue

l

an

d

t ar

g

et ele

m

e nt s tha t wer e u s e

d i

n the

n u cle a r

_p

r o

d

u ct

i

o n

_p

r o ces s we r e

_p

r o

d

u c e

d

in

M

a r e a. Du r

i

n

g

the

m

etals fa

b

ric at

i

o n

p

r o_{c e}s_s,

m

e t a

l

s

w

e r e

d

e

g

r e a s e

d

w

i

t

h

s o

l

v e n ts,

p ri m

a

ri l y T C

E, P

C

E, a n

d 1

,

1

,

1

-t

ri

c

h l

o r o et

h

a n e

(

T

C

A

)

.

A

n e stimate

d 6 m i l l i

o n

k i

lo

g

r a

m

s

(

1

3 m i

l l

i

on

p

o u n

d

s

)

o

f

ch lo

ri

n ate

d

s olv e nts we r e u s ed be_twe e n 1

9 5

2 a nd 1

9 8

2. T he wa ste s olv e nts

w

e r e d ir e cte

d

t o a s e tt

l i

n

_{g b}

as

i

n

_{b y}

_wa

_y

o

f

a s ewer

l i

n_e.

L

e a c

h i

n

g f

ro

m

t

h

e s et t

l i

n

g b

a s

i

n a n

d

a

l

e a

k i

n

t

h

e s e

w

e r l

i

n e has

l

e

d

t o co nta

m i

n at

i

o n of the

_g

r o u n

d

w a t er an

d

s u

b

s u r fa c e se

d i

m

e n t s

i

n

M

-a r e -a. T

C

E c o nta

m i

na tio n o c c u r r e

d p ri m

a

ri l

y at

d

e

p

t

h

s

g

reate r t

h

an 1

0 0 f

ee t

(

3 0

.

5

m

e t ers

₎

.

A b

ove

10 0 f

e et

(

3 0

.

5

m

ete rs

)

i

s c on s

i d

ere

d

t o

b

e t

h

e u nc onta

m i

na t e

d

z o ne.

A

n

a

i

r _st

ri p p i

n

_g

(

_p

u

m

_p

a n

d

tr ea t

)

s_y ste

m

i

n sta

l l

e

d

at t

h

e

SR S i

n

19 84 h

a s s

i g

n

i fi

c an t

l y

r e

d

u c e

d

t

h

e a

m

o u nt o

f T C E i

n _t

h

_e s u

b

s u r

f

_{a c}e.

T h

e re

m

o v a

l

e

f f i

c

i

e nc

y

o

f

t

h

e a

i

r st

ri p p i

n

g

s

y ste

m

s

d

e c r e a s es

d

r _{a s t}

_i

_{c a}

_{l l}

_y as t

h

e

T C E

c o nc entra t

i

o n s

i

n t

h

e

_g

r o u n

d

wate r are r e

d

u c e

d

, an

d

r e

d

u ct

i

o n o

f

T

C

E

b

elow certa

i

n c o nc entr at

i

o n

l

eve

l

s a re

d i f f i

c ult. In an a t te

m

C

ar o

l

in a

T

e st

L

o c at

io n

Augu sta Sa v a n n ah

S O UT H

CA ROL I N A

G E O R G A

i

m

_{p l}

e

m

e nte

d

.

M

etha n e wa s

in

j

e cte

d i

nto t

he

s u

b

s u r

f

ac e to st

im

ulate

m

e tha ntr o

p h i

c

b

ac t er

i

a,

w h i

c

h

a r e

k

n own t o

d

e

g

r a

de

T

C E

(

Wi l

son et. al.,

19 8 5

; Fo

g

el et. a

l

.

, 1

9 86

; L

it t

le

et. a

l

.

19 8 8

)

.

T h i

s

i

n s

i

t u

b io r e

m

e

d i

a t

io n

d

e

m

o n str at

io

n at t

h

e

SR

S

e x a

m i

n e

d

the e

f f

e c ts

t

h

a t v a r

i

o u s n utr

ie

nt c o

m b i

n at

io n s

ha

d

o n t

h

e s u

b

s u r

f

a c e

m

ic r ob

i

o

l

o_{g y} a n

d

the fate o

f

T

C

E in the s ubs u rfa c e.

A

n

i

m

_p

ort ant en

d p

o

i

n_{t o}

f b i

_or_e

m

e

_{d i}

a t

io n

is

t ox

ic

i

t

_y

.

T

o o o

f

te n r e

d

u ctio n o r

d i

sa

_{p p}

e a r a nc e o

f

t

h

e ta r

_g

e t co

m p

o u n

d i

s t

h

e o n

l y

e n

d p

o

i

n t e x a

m i

ne

d

w

i

t

h

o u t c o n s

i d

er

in

_g

the

b

_y

-pr o

d

u cts fo r

m

e

d d

u rin_g the

b

io r e

m

ed iatio n.

Wh

e n i

m

p le

m

e ntin

g b

io r e

m

ed iatio n

t

h

e t ar

_g

et co

m p

o u n

d i

s

i d

e a

l l

_y

m i

n e r_a

l i

z e

d

t o

C O

_j an

d

H_j

O

,

h

o

w

e v e r , t

h i

s

d

o e s n ot a

l

ways

o c c u r .

So

m

et

i m

e s r e c a

l

c

i

tr a nt

b y

-p

r o

d

u c ts a r e

f

o r

m

e

_d

, a n

d

s o

m

et

i m

e s t

he s e

b

y

-p

r o

d

u cts

a r e

m

o r e to xic tha n the _pa r e nt c o

m p

o u nd.

B i

o

l

o

_{g i}

c a

l

tox

i

c

i

t

_y

a s s a

_y

s can

b

e us e

d

t o

m

on

i

_tor _t

h

e _tox

i

c

i

_{t y} r_e

m

ain

in

_{g i}

n t

h

e

s a

m

_{p l}

e s

fr

o

m

s

i

te s u n

d

e r

_g

o

i

n_g r e

m

e

d i

at

io n

. T he to x

ic

i

ty

is u se

d

a s a n

in

d i

c at

io n

o

f

t

h

e

h

a z a r

d

s t o

h

u

m

a n

h

e alth a n

_d

the en v

ir o n

m

_ent.

B

a cte

ri

a

l

as s a

y

s ha v e s e v e r al a

d

v a nta

g

e s

o v _er o t

h

er

b i

o

l

o

_{g i}

_ca

l

a ssa

_y

s. T

h

e n u

m b

er o

f b

ac te

ri

a u se

d i

n t ox

ic

i

t

y

as s a

y

s

is

q

u

i

te

l

a r

g

e,

w

hi

c

h i

s

f

a vora

b le

t o st a t

i

stica

l

a n a

l

_ys

i

s.

B

a ct e

ri

a a re also

m

uc

h

e a s

ie r

to

m

a

i

nta

i

n t

h

a n

h i g he r o r_ga n is

m

s, w h ich r edu c e s c o st a nd labo r.

M

ic r oto x

® _{a nd}

_M

_{ut a t ox}® _{a r e two u s eful}

bacte

ri

a

l

to x

i

c

i

t

_y

assa

_y

s t

h

a t a re

_g

a

in

i

n

_g

re co

_g

n

i

t

io

n.

T h

e

M

i

c r o t ox

®

_A

s s a

_y

us es a

l

u

m i

n e s c e nt

m

a r

i

n e

b

a_cte

ri

a

,

P h

oto

h

ac t er

iu

m p

h

osp

h

o r eu

m

to

d

ete ct a c ute to x

i

c

i

ty w

h i l

e

the

M

utato x®

A

s s a_y u s e s a

d

a r

k

r e v e rta nt o

f

a

l

u

m

in e s c e nt

b

a cte

ri

a

, V

i b

rio

fi

s c

h

e r

i

M

16 9,

to

d

et e c t

_g

e n oto x

i

c

it

_y.

T h

es e a s sa

y

s

y i

e

l d

r e s u

l

ts

i

n a s

h

ort a

m

o un t of t

i m

e an

d

a t a

re

l

at

iv

e

l

_y

l

ow co s t, a n

d

a s a r e s u

l

t the

y

a r e

be

c o

m i

n

g p

o

p

u

la r

to o

l

s

f

o r

m

o n

i

to

ri

n

g

tox

i

c

it

y

i

n e n v

i

r o n

m

e nta

l

sam

_{p l}

e s.

T h

e o

b

_j

ec tive so

f

th is re se a rc

h

wer _{e t o e}v_a

_l

ua te wa t er an

d

su

b

su r

f

ac e s e

d im

e n t

s a

m

_{p l}

esc o

l l

ecte

d d

u

ri

n

_g

a n

_d

a

f

_te r t

h

e

b i

o r e

m

e

d i

atio n

d

e

m

o n str at

io n

a t the

SR

S f

o r

obs e r v e tr e n

d

s in the a c ute to x icit_y a nd ge n oto x icit_y o v e r ti

m

e, a nd c o r r elate the s e tr e n

d

s

H

e a

l

t h E

f f

e cts o

f

T

C

E

A

cut e e

f f

e c t s o

f

T

C E

ex

_p

o su re a re

m

o s t

l

_{y t}o t

h

e ce ntra

l

ner vou s s

_y

s t e

m

(

C N S

)

(

A

T

S

D R ,

19 8 9

)

.

D i

z z

in e s s

, he a

d

a c

h

e, s

l

e ep

i

n e s s, slowe

d

r e a ctio n t

i m

e, a n

d f

ac

i

al

n u

m b

ne s s

h

av e

b

een o

b

s e r v e

d i

n

_p

eo

_p

le ex

_p

os e

d b

_y

T CE

b y b

o th in

_g

e st

i

o n a n

d i

n

h

a

l

a t

i

o n

ro u te s.

E f f

e c t s

h

ave

b

e en o

b

ser ve

d

at e x

p

o su r e t o

d

o s es a s

lo

w as

5 0 p p

m

i

n a

i

r

(

A

T

SD

R

,

19 8 9

)

.

A

t

l

ow

d

ose s,

C

N

S

e

f fe c

ts a r e r e v e r si

b

le w he n e x

p

o s u r e c e a s e s.

U

n c o nsc

io

u s n e s s a n

d d

e ath ca n res ult

f

r o

m in

_g

es t

io n

o

f

v e r_y

h i gh

c o n c e ntr at

i

o n s

(

7 0 0 0

m

_g/

_{k g}

_{) (}

A T S D R

,

19 89

)

,

h

owe ver t

h

e se c o n ce ntr atio n s are s e

l d

o

m

f

o u n

d i

n the

e n v

i

r o n

m

e n_t.

C

hronic e

f f

e c t s that ca n

d

ev elo

_p

a

f

te r lo n

_g

e x

_p

o s u r e to low con c e ntr atio n s o

f

T

C E

in

c

l

u

d

e c a r c

in

o

_g

en esis a n

d

te rato

_g

e n e s

i

s.

T C E h

a s

b

ee n s

h

own to

b

e c ar c

in o

g

e n

i

c

i

n

s e v e r al s

_p

e c

ie s o

f labo r ato r_y a ni

m

als

(

H

e n s ch le r et. al.,

19 8

4; In

f

a nte, 1

9 8 7

; Fa n, 1

9 8 8

)

,

a n

d

c a u s a

l i

t_y

be

twe e n T

C

E e x

_p

o s u r e an

d

the

d

e v elo

_{p m}

e nt of le uke

m i

a ha s

b

e e n s u

_{g g}

e ste

d

(

L

a

_g

a

k

o s et. a

l

.

,

19 8 6

)

.

S

ev e r a

l i

n

d

e

p

en

de n

t stu

di

e s u sin

g

av

i

a n an

d

r a t

m

o

d

e

l

s

h

a ve

f

o u n

d

si

_g

n

i fi

cant

i

n c r e a s e s

i

n

f

eta

l

c a r

d i

a c a

b

n o r

m

a

l i

tie s

i

n a n

im

als e x

_p

o s ed t o

T C

E

(

Lo

b

e r et. al., 19 8 8; D aw s o n et. a

l

,

19 9 0

)

. T e r atoge n

ic e

f f

e cts

h

a v e a

l

s o

b

e e n r e

po rte

d

_{t o}

occ u r

i

n r a

b b i

ts ex

_p

o se

d

to

T C E

(

M

u rr a

_y

et. a

l

.

,

19 79

)

.

A

n e

p i d

e

m i

o

l

o

g i

ca

l

stu

d y h

as

r e

_p

o rted a n in c r e a s e

in

c o n_ge nita

l

he a rt d is e a s e a

m

o n_{g h}u

m

a n s

d

r

in

k in

_g

_wate r

c o nta

m

i

n at e

d w i

th T

C E

₍

G

ol

d b

e r

_g

et. a

l

.

,

19 9 0

)

. H owever

, t

h

e

d

r

i

n

k i

n

g

wa te r co nta

in

e

d

s e v e r a

l

a

d d i

t

i

o n a

l

c

h

e

m i

c al c o nta

m i

nants, t

h

er e

f

or e

i

t

is n o

t c

le a r

w h

e t

h

e r

T C E

, a n othe r

ef fe cts obs e r v ed. A ltho u

g h the he alth ef fe c ts of lo n_g

-te r

m

e x _po s u r e to T C E a r e n ot cle a r,

a ni

m

al

d

ata s u_{g g}e st that T

C

E e x_po s u r e _pr e s e nts a he alth ha z a r

d

.

G

r o u n

d

W

ater

R

e

m

e

d i

a

ti

o n o

_f

V O C

s

O p

tio n s fo r r e

m

e

di

atin

_g

c o nta

m

in ate

d g

r o u n

d w

ate r in clu

d

e

_p

h ys

i

c al, che

m

ic al,

a n

d b i

olo

_{g i}

cal treat

m

e nt. T he se te chn olog

i

e s c a n

be

a

p p U

e

d

eithe r ex situ o r in situ .

"

Pu

m

_p

a nd tr e at", o r e x situ r e

m

ed iatio n, is the

m

o st c o

m

m

o n ty

p

e of tr e at

m

e n t. It is a

p h

y s

i

c a

l p

r o c e s s w

h

ich

i

n v olve s

_p

u

m p i

n

_g

t

h

e

_g

r o u n

d

wate r to t

h

e s u r

f

a c e_, r e

m

o v

in

_g

the

co nta

m i

nant s, an

d

re tu

rn

in

g

the wate r to the a

q

ui

f

e r . A ir s tri

p p

in

g i

s a co

m

m

o n e x situ

p h

ysic a

l

tre a t

m

ent tec

h

no

l

o

_gy

u s e

d

to re

m

ove vo

l

at

i l

e c o

_{m p}

ou n

d

s.

A h i gh

ratio o

f

c on_tac t

b

e twe en t

h

e water an

d

a

i

r

i m p

rove s the

_p

art

it

i

on

in

_g

o

f T C E f

ro

m

w a t er t o a

i

r.

T h

e a

i

r

m

u st

b

e tr e ate

d

a

f

te r the c o nta

m i

n a nt

i

s str

_{i p p}

e

d fr

o

m

t

h

e

w

a te r.

A

c o

m

m

on

s e c o n

d

a r_y tr e atme n t, o r a

i

r tr e at

m

e nt, is

g

r a n ula r a ct

i

v ate

d

c a r

b

o n

(

G

A

C

)

a

d

s o r

p

t

i

o n.

T

h

e c o nta

m

in a nt in the air is tran sfe r r e

d

to the

G

A

C

f Ute r. T he f i lt er

m

u st

be

d is

p

o se

d

of

a s a

h

a z a r

d

o u s wa ste

b

e c a u s e t

h

e c o nta

m i

nant

i

s r e

_g

u

la

te

d

u n

d

er t

h

e

R

e s ou r c e

C

o n s e r v at

io n

a nd Re c o v e r_y

A

c t

₍

R

C

R A

₎

. A c o

m m

o n

d i

s a

d

v a nta

g

e of

bo

th a

i

r str

i p p i

ng

a n

d G A C

a

d

so r

_p

t

io n

is

t

h

at t

he

c o nta

m i

nant

is t

ran s

f

e r r e

d fr o

m

o n e

m

e

d iu

m

t o an ot

h

er

r athe r tha n

b

ein_g eUmin ated.

U V

o x

i d

at

io n

is a c

he

m i

c al tr e atme nt te c hn o

l

o

_g

_y that

d

e stro_ys the c o nta

m

i

n a nt

r athe r tha n tr a n sfe r rin_{g i}t to a n othe r

m

ed iu

m

w h ich

m

_{i g h}t

_p

r e s e nt a ha z a r

d

in the futu r e

(N y

r e a n

d

M

or el

lo

, 19 9 3

)

. T h

i

s

f

o r

m

o

f

tr e atment

i

n v olve s e x

p

o s

in

g

t

he

c o nta

m

i

n ant to

ultr a v

i

o

l

et r a

d i

atio n a n

d

a n o x

i d

a nt s u c

h

a s

_p

e r o x

i d

e o r o z o ne

in

a n a

b

o v e

_g

r o u n

d

r ea ctor.

T

h

e

U V

ra

d ia t

io

n enhan c e s the ox

i d i

z

i

n

_{g p}

o t ent

i

a

l

o

f

the ox

i d

an ts.

U V

ox

i d

at

i

on c an

d

es tro

_y

u

_p

t o

9 9 %

o

f

the T

CE

_p

r e sent,

p

r o

d

uc

in

g

a

h

ar

m l

e ss c

h l

o r

i d

e

io

n as an e n

d

p

r o

d

u ct

(N y

re a n

d

M

or e

l

lo,

19 9 3

)

.

O

n e

m

a

_j

o r

_{d i}

s a

d

v a nta

_g

e of a

_p

u

m

_p

a n

d

tr e at a_p

_p

r o a c

h

to c

le a n

i

n

_g

u

_p

a s

i

te

is

t

h

at

b

e _pu

m

_pe

d

to the s u rfa c e.

W

a te r s olub i l ity, ads o rp ti o n, a nd

d

i f fu sio n ra te s of the che

m

ic al

c o nta

m

in a nt, a s wel l a s the

g

e olog ic c o

m p

o sitio n of the s ubs u r fa c e, a r e fa cto r s in

d

ete r

m i

n

i

n

_g

w he the r the c o

m p

o u n

d

w

i U b

e e a s

i l y p

u

m p

e

d

to t

h

e s u r

f

a c e

f

or tre a t

m

e nt.

In s

i

tu r e

m

e

d

ia

ti

o n cir c u

m

v e nts s o

m

e _pr o

b l

e

m

s

f

a c e

d

w it_{h p}u

m p

a n

d

tr e at

te chn olo

_g

ie s a n

d i

s

m

u ch

m

o r e c o st e

f f

e c

ti

v e. V apo r e xtr a c

ti

o n

i

s a

p

h ys

i

c al tr e at

m

e nt

ana

l

o

_g

o u s to a

i

r s tr

i p p i

n

_{g b}

ut o c cu rs

i

n t

h

e su

b

su r

f

a c e.

A i

r

i

s

p

u

m

p

e

d i

nto t

he

v a

d

o se

z o n e, w h

i

ch c a u s e s v ola

ti

le co

m p

o u n

d

s to pa r

ti ti

o n

f

r o

m

the wate r p has e to t

h

e air p ha s e.

A

d

is adv a nta_ge of th is a_{p p}r o a ch is that s e c o nda r_y tr e at

m

e nt

f

o r the air

i

nto

w

h ich the

co nta

m i

nant s

_p

a rti ti o n e

d i

sr e

_q

u

i

r e

d

. B

i

o

l

o

g i

c a

l i

n s

i

tu r e

m

e

d i

a

ti

o n

i

s a tr e at

m

e nt

te c hn olo

_gy

that

i

s s_pa rk in

_g

a

l

ot of inte r e st a n

d

r e sea r ch. An adv a nta

g

e of

b

io r e

m

e

d

iatio n

i

s that the c o nta

m

in a nt

i

s el

im

i

n ate

d

r athe r tha n

b

e

i

n_g tr a n s

f

e r r e

d f

r o

m

on e

m

e

d i

u

m

to

a n o the r.

N

utr

i

ents a n

d

c o

m p

ou n

d

s s e r v

i

n

g

as e

l

ec tron a c c e

p

t or s ca n

b

e

p

u

m

p

e

d i

nto the

g

rou n

d w

ate r to s

ti

m

ulate the n a

ti

v e

b

a cte r

i

a, o r

f

o r e

i g

n

b

acte r

i

a c an

b

e a

d d

e

d

a

l

on

g w

ith

the n utr

i

ents to

d

e

_g

r a

d

e the conta

m i

n a nt.

Sti m

ulat

i

n

g

the n a

ti

v e

m i

c r oor

g

a n

i

s

m

s

i

s

p

r e

f

e r re

d b

eca use

f

o r e

i g

n

m i

cr o o r

_g

a n

i

s

m

s

d

o n ot co

m p

ete

w

el

l w i

th n a t

i

v e co n s o r

ti

a.

M

i

c r o

b ia

_{l D}

e_gr a

da

ti

o n o

f

T

C E

M

etha n o

_g

e n s

M

etha n o

_g

e n s a r e a

_g

rou

_p

o

f

a n a e r o

b

ic

_{ba c t}

e r

i

a t

h

at a r e

_p

art o

f

a c o n sor

ti

a a

b l

e t o

tr a n sfo r

m

T

C

E

i

nto othe r c o

m p

o u n

d

s. Du rin

g

n atu r al

m

eta

b

ol is

m

,

m

et

h

a n o

g

e n s u s e

H

2

o r a si

m

_{p l}

e o r

_g

a n

i

c c o

m

_p

o u n

d

as a n e

l

e c tr o n

d

o n o r a n

d C O

j a s a n ele ctr o n a c c e

p

to r, a n

d

p

r o

d

u c e

m

et

h

a ne a s a

b

_y

-p

r o

d

u ct. In the

p

r e s e n c e o

f

T

C

E,

m

etha n o

g

e n s c a n u se T

C

E

r athe r than

C O

2 a s an e

l

e c tr o n a c c e

_p

to r

i

n a

_p

r o c ess known a s re

d

u c

ti

ve

d

e

h

a

lo

_g

en a

ti

o n .

Re

d

u c

ti

ve

d

ehalo

_g

e n a

ti

o n

b y m

etha n o

_g

e n s occ u rs a

m

on

_g

m

a n

_y

halo

_g

e nat e

d

h

_{y d}

r o c a r

b

ons

W

hen a halo

_g

en ated h y

d

r o c a rbo n is u sed a s a n ele c tron a c c e

_p

to r, a haloge n is

r e

m

o v e

d

a n

d

r e

_{p l}

a c e

d

w

i

t

h

a

h

_y

d

r o_ge n.

C

o

m

po u n

d

s w

i

th

l

ow

h

alo

g

e n

-c a r

b

o n

b

o n

d

e n e r_{g i}e s a r e

m

o r e l i kel y to

b

e u s ed a s ele ctr o n a c c e_pto r s

b

_y

m

etha n o_ge n s tha n c o

m

_po u nds

w i

t

h hi g h h

alo

_g

e n

-c a r

b

o n

b

o n

d

e n e r

_{g i}

e s

b

e cau s e we ak

b

on

d

s ar e

m

o r e e a s

i l

_y

b

ro

k

e n

b y

t

h

e or

_g

a n

i

s

m

s

(

V

o

_g

e

l

et. a

l

.,

19 8 7

)

.

I

n

g

ener a

l

, t

h

e

m

o s t

h i gh l

y

h

a

l

oge n ate

d

c o

m

p

o u n

d

s

w

ith in a _gr o u_{p h}a v e lowe r c a rbo n

-halo_ge n

b

o nd e n e r_{g i}e s a nd a r e

m

o r e l i kel y to be u s ed a s

e

l

e ctr o n a c ce

_p

t ors t

h

a n co

_{m p}

o u n

d

s w

i

t

h f

ewe r

h

a

l

o

_g

e n s.

T h

e ch

l

o r

i

n ate

d

eth y len e s a r e a n

e x a

m

_{p l}

e o

f

a

_g

r o u

_p

o

f

co

m p

o u n

d

s that u n

d

e r

_g

o r e

d

u ct

i

v e

d

e ch lo r

i

n at

i

o n

b y

m

e tha n o

_g

e ns

(

F

i

_gu r e

2

.

1

)

.

O f

the c

hl

o rin ate

d

eth y

l

e n e s, tetr a ch lo r o eth

y l

e n e

(

P

C

E

)

i

s the c o

m

po u n

d

m

o st e a s

i l y

re

d

uc e

_{d b y m}

e t

h

a no

_g

ens

b

e c aus e o

f i

t s

f

ou r c

hl

o

ri

ne s an

d

t

h

e re

l

at

i

ve

l y

wea

k

c a r

b

o n

-c

h l

o

ri

n e

b

o n

d

en e r

_{g i}

e s.

M

et

h

a n o

g

e n s a r e

k

nown to r e

d

u c e P

C

E to

T C E

, an

d

r edu c e T

C

E to

d

ich lo r o eth y le n e

(

D

C

E

)

. 1,

2

-D

C

E h

a s

b

e e n shown to

b

e the _pr e

d

o

m i

n a n t

i

s o

m

e r fo r

m

e

d

(

K l

e o

_{p f}

e r et. al., 1

9 85

)

.

D C

E

i

s

m

o r e r e s

i

sta nt to

d

e c h lo

ri

n at

i

o n

b

e c a u s e

t

h

e

b

o n

d

e n e r

_{g i}

e s a r e s tr o n_ge r,

b

ut

h

a s

b

e e n r e

p

o rte

d

to

b

e r e

d

uc e

d

to v

i

ny

l

c

h

lo

ri d

e

(

V C

)

(

V o_gel a n

d

M

c

C

a rt_y,

19 85

;Ba rri o -L

a_ge et. al., 1

9 8 7

; Bae

k

a n

d J

a

f f

e, 1

9 8 9

;

S

ewel l et. al.

19 9 1

)

.

V C h

a s a ver

y

s tron

g

c ar

b

on

-c

h l

o

ri d

e

b

on

d

ener

_gy

, w

i

t

h

on

l y

one c

h l

o

ri d

e, an

d

t en

d

s t o

b

e re s

i

s ta nt to

m

et

h

a n o

_g

e n

i

c

d

e

_g

r a

d

at

i

o n.

V C i

s t

h

e

m

o s t t ox

i

c o

f

t

h

e c

h l

o

ri

n ate

d

et

h

_y

l

e n e s a n

d i

s a

k

n ow n a n

i m

al a n

d

hu

m

a n c a r cin o_ge n

(

M

a

l

t

i

n

i

a n

d

Le

f

e

m

i

n e, 1

9

7 4

)

.

Both D

C

E a n

d

V

C

ha v e

b

e e n r e

_p

o rte

d

a s the

f

in al

_p

r odu ct o

f

P

C

E r e

d

u ct

i

o n

b y

m

etha n o_ge n s

(

K le o_{p f}e r et. al.,

19 8 5

;

S

c

h

olz -

M

u r a

m

ats u e t. a

l

.,

19 9 0

;

G i b

s o n a n

d S

e

w

e

l l

,

1 9 9 0; Sewel l a n

d G

i bs on , 1

9 9 0

;

S

ewel l et. al., 1 9

9

1;V ogel a nd

M

c

C

a rty, 1

9 8 5

; Ba rri o

-L

a

_g

e et. a

l

.,

19 86

;

B

a r

ri

o -

L

a

_g

e e t. a

l

.,

19 8 7

;

B

a e

k

an

d J

a

f f

e,

19 8 9

;

S

e

w

e

U

et. a

l

.,

19 9 1

)

.

T

h

e

fi

n a

l p

r o

d

u ct

m i

_g

h

t

b

e

d

ete r

m i

n e

d b

_y t

h

e a v a

i l

a

b i l i

t_y o

f

e

l

e ctr o n

d

o n o r s.

M

i

x e

d

m

etha n o

_g

e n ic c ultu r e s

m i

_g

h

t

i

n clu

d

e fe r

m

e nt

i

n

_{g b}

a cte

ri

a w h ich pr o

d

u c e H_j , a n e

l

e ctr o n

d

o n o r,

f

o r t

h

e

m

etha no

g

e n s.

S

yste

m

s t

h

a t

h

a v e a n a

b

u n

d

an ce o

f H

H

C

I

\

=

_C

^

_{T C E}

H C I

c r

H

_c

_r

_C

I

tr a n s -1,

2

-

_{D C E}

c

i

s-₁ ,

2

-

D C E

X

_:

_H

_C

_I

H

C I

v

c

H

₂

/

H C I

H

C

—

C

_{E th y l}

_{e n e}

H

C O 2

F i g

u re

2

.

1

.

R

e

d

uct

i

ve

d

e c

h l

or

i

n at

i

on o

f T C E b

1 1

T he fate of

V

C in a n a e r ob ic c o nd itio n s _ge n e r al l y s e e

m

s to be a c c u

m

ulatio n. U nde r

c e rt a

i

n con

_{d i}

t

i

o n s, howe v e r , V

C

is

m

in e r al iz e

d

into in n o c uou s

p

r o

d

u cts. Eth

y

le n e,

ch

l

o r o et

h

a n e, ch lo r o

m

etha n e,

m

et

h

a n e, a n

d C O

_j ha v e be e n r e

p

o rte

d

a s V

C

tr a n s

f

o r

m

atio n

p

r o

d

u cts

(

B o uwe r a nd

M

c

C

a r t_y, 1 9 8 2; Fr e ed

m

a n a n

d G

o ss et t, 1 9

8 9

; V o

g

el a n

d

M

c

C

a rt_y, 1

9 8 5

; Ba r r

i

o -_La

g

e et. a

l

, 1

9 86

; Ba r r

i

o -_L

a

_g

e et. a

l

., 1

9 9 0

)

. Et

h y l

e n e wa s

f

o r

m

e

d

b y the r e

d

u ct

i

v e

d

e c h lo rin atio n of V

C

(

Fr e ed

m

a n a n

_{d G}

o s s et t, 1

9 8 9

; Ba r rio -L _a

g

e

et. al ., 1

9 9 0

)

,

w h

ich w a s the n

m

in e r al

i

z e

d

to

f

o r

m C O

_j

(

V o

g

el a n

d

M

c

C

a rty , 1

9 8 5

;

Fr e e

d m

a n a n

d G

o s s et t, 1

9 8 9

)

. T he

m

e cha nis

m

s

by

w h ic

h

c

h l

o r o

m

etha n e a n

d

ch lo r o et

h

a n e w e r e _pr o

d

u c e

d

a r e u n cle a r.

C

h lo r o

m

etha n e cou

l d b

e

p

r e c e

d

e

d b

y the

c

h

lo r o et

h

a n e, an

d

ch lo roetha n e c o ul

d b

e

f

o r

m

e

d b

y the h y

d

ro

g

e n at

i

o n of

V C

. Pe rha

p

s

c er_ta

i

n _{c o}n

_{d i}

_t

i

o ns enco u ra

_g

e t

h

e

b

re a

k d

ow n o

f V C i

nto c

h l

o ro e t

h

ane.

B

a e

k

an

d J

a

f f

e

(

1

9 8 9

₎

s u_{g g}e ste

d

that a n a

b

u n

d

a n c e of

f

e r

m

e nto r s _pr e s e nt

i

n the

d

e_gr a

d

a t

i

o n c ultu r e

w

o ul

d

s u

_{p p l}

_y a

m

_{p l}e

H

j to c a u s e t

h

e h y

d

r oge n atio n o

f

V

C

.

T h

e r e c a

l

c

i

trant

_p

ro

d

u cts

f

or

m

e

d b y

r e

d

u c t

i

v e

d

e

h

a

l

o

_g

e n at

i

o n o

f T C E

(

D

C

E a n

d

V C

₎

a r e ea s

i

l y

d

e

_g

r a

d

e

d b y

s o

m

e a e r o

b i

c o r

_g

a nis

m

s.

O

n e ap

p

r o a c

h

o

f

tak ing a

d

v a nta

g

e

o

f

the

d

e

_g

ra

d

a t

i

ve a

b i l i

t

i

es o

f m

et

h

a n o

_g

e ns

i

s t o

f

o

l l

ow an aer o

b i

c tre a t

m

en t

w i

t

h

a e ro

b i

c

tr e at

m

ent.

T h i

s

i

s

f

e a s

i b l

e

i

n a n a

b

o ve

g

rou n

d

r e a cto r,

h

ow ev e r

i

s

d i ff i

c u

l

t to a

p p l y i

n s

i

tu .

In s

i

tu

m

etha n o

_g

e n

i

c

b i

o r e

m

e

d

iatio n w a s te ste

d

at an E P

A d

e

m

on str at

i

o n sit e to

dete r

m

ine its e

f f

e ctiven e s s a n

d p

r a ct

i

ca

b

i Ut_y.

C

lai

m

s of s u c c e s s

m

a rke

d b

y r e

m

o v al o

f

P

C

E a n

d T C E b y

r e

d

u ct

i

ve

d

e c

h l

or

i

n at

i

o n an

d

c o st e

ff

e c t

i

ven es s are ta

i

nte

d b y

t

h

e

f

act

that

V C l

ev els were n ot

m

onito r e

d

. P

C

E, T

C

E, a n

d

cis

-D

C

E w

e r e

m

o n

i

to r e

d

fo r a n

_d

f

o u n

d

to s e

_q

u e nt

i

a

l l y i

n c r eas e a n

d d

e c r e a s e, w

h i

ch

m i g

ht

i

n

d i

c ate t

h

at r e

d

u ct

i

v e

d

ec

h

lo r

i

n at

i

o n

w

a s occ u r r

i

n

_g

(

S

ew e

l l

e t. a

l

.

,

19 9 0

)

.

T h

e

f

ac t t

h

at

V C w

a s n ot

m

o n

i

tor e

d

at the s

i

t e

i

s a

m

a

j

o r

f l

aw

i

n t

h

e stu

d

_y, a n

d l

e a v e s s o

m

e

q

u e st

i

o n a s to w

h

ethe r o r n ot the

s

i

te ha

d

actu a

l l y b

een "cleane

d

u

_p

"