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NATURAL RADIOACTIVITY I N NORTH CAROLINA GROUND WATER SUPPLIES

Marc Y. Menetrez

Department o f Chemical Engineering N o r t h C a r o l i n a S t a t e U n i v e r s i t y

Raleigh, NC 27650

James E. Watson, 3 r .

Department o f Environmental Sciences and E n g i n e e r i n g Uni v e r s i t y o f N o r t h Carol i na

Chapel H i 11

,

NC 27514

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ACKNOWLEDGMENTS

This report i s based upon a t h e s i s prepared

by

the senior author while

a graduate student in the Department of Civil Engineering

a t Duke University.

He would l i k e t o express his sincere appreciation t o Professor

P.

Aarne

Vesilind, the Chairman of his Advisory Committee, f o r his kind guidance.

Thanks are also extended t o the other members of his committee, Professors

Arthur

W.

Maltner, Henry

J .

Petrosky

a n d 3.

Jeffrey Pierce, f o r t h e i r con-

s t r u c t i v e criticism and suggestions. Finally, he would l i k e to express spe-

cial thanks and deepest appreciation t o his wife, Mary Menetrez, f o r her

support, patience and understanding without which t h i s study and graduate

education could never have been completed.

Urani urn analyses of three samples used in t h i s report were made by

Ms.

J .

Michel a t the University of South Carolina Department of Geology

Laboratories. All other analyses were made by Ms. Shirley Be1 1 a t the

North Carolina State Laboratory of Public Health. The authors are grate-

ful to Ms. Bell f o r her helpful assistance in the preparation of t h i s

report.

Appreciation

i s

also extended t o

Mr. James

F .

Stamey, Section Chief,

and the s t a f f of the North Carolina Environmental Health Section f o r t h e i r

cooperation and support without which t h i s report would not have been

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ABSTRACT

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TABLE OF CONTENTS

Page ACKNOWLEDGMENTS

. . .

i i

ABSTRACT

. . .

iii

LIST OF FIGURES

. . .

v

LIST OF TABLES

. . .

v i SUMMARY. CONCLUSIONS AND RECOMMENDATIONS

. . .

v i i INTRODUCTION Purpose

. . .

1

Federal and S t a t e Standards

. . .

1

PROCEDURES

. . .

7

RESULTS AND DISCUSSION

. . .

8

N a t u r a l R a d i o a c t i v i t y i n N o r t h Carol i n a

. . .

8

Gross Alpha and Radium C o n c e n t r a t i o n s

. . .

8

Radium-228 t o Radium-226 R a t i o s

. . .

13

Uranium C o n c e n t r a t i o n s

. . .

15

Treatment o f Water f o r Removal o f R a d i o n u c l i d e s

. . .

17

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LIST OF FIGURES

Page 1. Flow C h a r t f o r Gross Alpha P a r t i c l e A c t i v i t y and

Radium M o n i t o r i n g

. . .

.

.

.

. . .

.

. .

.

.

.

.

5

2. County D i s t r i b u t i o n o f V i o l a t i o n s o f Standards

. . .

.

.

.

.

.

.

11

3. C o r r e l a t i o n Between 2 2 6 ~ a and T o t a l Uranium

. . .

. . .

. . .

.

19 4. T o t a l Hardness Removal as a F u n c t i o n o f Raw Water

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LIST OF TABLES

Page 1. Gross Alpha P a r t i c l e A c t i v i t y o f Those Systems Exceeding

Federal and S t a t e Standards

. . .

9 2. 2 2 6 ~ a , 2 2 8 ~ a and Combined Ra o f Those Systems Exceeding

Federal and S t a t e Standards

. . .

10

3. 2 2 8 ~ a / 2 2 6 ~ a R a t i o o f Those Systems Exceeding t h e Radi urn

Standard

. . .

14 4. T o t a l Uranium Content ( 2 3 4 ~ and 2 3 8 ~ )

. . .

16

5. L i s t i n g o f t h e Average and H i g h e s t C o n c e n t r a t i o n s o f Gross Alpha P a r t i c l e A c t i v i t y , Combined Radium and T o t a l Uranium

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SUMMARY,

CONCLUSIONS

AND

RECOMMENDATIONS

The Safe Drinking Water Act monitoring requirements for radionucl ides

in pub1 i c water supplies i n i t i a t e d the 1 argest radiological inventory of

ground water ever before undertaken. In the State of North Carolina as of

August 1 , 1982, 2,089 water systems had been analyzed. Of these systems,

2.4 percent o r 51 water systems were found in violation of federal and s t a t e

standards. Thirty-nine systems o r 1.9 percent of those systems tested had

combined radium violations; an additional 12 systems o r 0.6 percent had

gross alpha violations and 14 of these systems o r

0.7

percent had both com-

bined radium and gross alpha violations. For systems in violation of the

standards, the average concentration of gross alpha was 29.5 pCi/l,

a n d

the

average concentration of combined radium was 12.2 pCi/l.

Using the average level of radium (12.2 pCi/l) and the percent of sys-

tems with radium violations (1.9 percent of those systems t e s t e d ) ,

a n d

the

present population of North Carolina using ground water

( 3

m i l l i o n ) , i t can

be

cal culated [using methods recommended by the Environmental Protection

Agency (1976b) based on the linear extrapolation

o f

the dose e f f e c t rela-

tionship] t h a t one person may die every 4.8 years from cancer due t o the

ingestion

o f

radium.

Based on the concentrations of radium found i n ground water used f o r

drinking purposes in North Carolina and the consequential health e f f e c t s of

t h i s form of radionuclide, the State Department of Human Resources and/or

the Environmental Protection Agency should i n i t i a t e treatment of water high

in radium.

An

examination of the 2 2 8 ~ a / 2 2 6 ~ a

r a t i o s f o r sys tems exceeding the

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radium-228 c o n c e n t r a t i o n s exceed t h e l e v e l s o f radium-226. To be s u r e t h a t a l l systems a r e i d e n t i f i e d which have combined radium i n excess o f 5 p C i / l , separate m o n i t o r i n g o f b o t h radium-226 and radium-228 would be necessary i f t h e l e v e l s o f gross a l p h a a c t i v i t y exceed 5 p C i / l . Considera- t i o n o f t h e c o s t - b e n e f i t aspects o f radium-228 m o n i t o r i n g i s needed t o e v a l u a t e t h e c u r r e n t c r i t e r i a f o r m o n i t o r i n g .

More than h a l f o f t h e systems examined w i t h a l e v e l o f gross alpha p a r t i c l e a c t i v i t y i n excess o f 15 p C i / l were a l s o shown t o have l e v e l s o f uranium i n excess o f 10 p C i / l . Examination o f l e v e l s o f uranium i n ground water systems having e l e v a t e d l e v e l s o f gross alpha a c t i v i t y should con-

t i n u e . I f l e v e l s o f uranium i n N o r t h C a r o l i n a i n excess o f 10 p C i / l con- t i n u e t o be found i n as many systems as was found i n t h i s study ( a p p r o x i - m a t e l y 50 p e r c e n t of those systems w i t h gross alpha exceeding 15 p C i / l ) and a t c o n c e n t r a t i o n s averaging near t h a t found i n t h i s s t u d y (27 p C i / l ) , stand- ards f o r uranium should be considered.

L i k e chemical o r b i o l o g i c a l contaminants, r a d i o 1 o g i c a l contaminants a r e cause f o r concern. I f t h i s concern m o t i v a t e s s t u d y t o l e a r n as much as p o s s i b l e about r a d i o l o g i c a l contaminants and t h e i r d i s t r i b u t i o n , we can deal w i t h them and improve o u r e n v i ronnent.

Recommendations

1. Treatment should be i n i t i a t e d on w a t e r systems w i t h radium concentra- t i o n s i n excess o f t h e standard.

2. C o s t - b e n e f i t analyses o f radium-228 m o n i t o r i n g s h o u l d be performed t o e v a l u a t e t h e adequacy o f c u r r e n t m o n i t o r i n g requirements.

3. Examination o f l e v e l s o f uranium i n ground-water systems should con- t i n u e i n o r d e r t o e v a l u a t e t h e need f o r a uranium standard.

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INTRODUCTION

Purpose

The Safe Drinking Water Act i n i t i a t e d the 1 argest radiological survey

of drinking water ever performed in North Carolina. All community public

water suppl i e s must moni t o r the radiological contents of t h e i r water accord-

ing t o federal and s t a t e regulations. The objective of t h i s study was to

examine the available 2,089 water system analyses f o r samples col lected

between June 24, 1979, and August 1 , 1982. The r e s u l t s a r e compared with

the regulations, and possible e f f e c t s on humans a r e examined. The types

of water treatment needed for radionucl ide removal are di scussed. Possi bl e

improvements to the Safe Drinking Water Act and improvements in monitoring

procedures f o r radionuclides are addressed.

Federal and State Standards

Generally, large water systems u t i l i z e surface water, which on the

whole contains very low concentrations of radionuclides unless there has

been a man-induced discharge from an upstream f a c i l i t y . Small water systems,

usually serving l e s s than 500 people, commonly use ground water, which may

contain naturally occurring radionuclides. Uranium and i t s decay products,

radium

a n d

radon, a r e the radionuclides of principal i n t e r e s t .

On

August 14, 1975, the Environmental Protection Agency

( E P A )

proposed

National Interim Primary Drinking Water Regulations f o r radioactivity pur-

suant t o the Safe Drinking Water Act,

P . L .

93-523. Taking e f f e c t on

June

24,

1979, in the State of North Carolina, these regulations made i t

mandatory t h a t a l l community pub1 i c water supplies (defined as having a t

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analyzed f o r radioactivity. Compliance i s based on the analysis of an

annual composite of four consecutive quarterly samples or the average of

the analyses of four separate samples obtained in consecutive quarterly

intervals. This procedure i s designed t o minimize the chance of variation

in the radionuclide content due t o seasonal changes in hydrologic conditions.

The Safe Drinking Water Act directed the

EPA

t o s e t standards f o r

drinking water t h a t "shall protect health to the extent feasible, using

technology, treatment techniques and other means, which the Administration

determines a r e general l y avail abl e (taking costs into consideration).

I'

The

maximum contaminant levels a r e based on the assumption t h a t there i s no

harmless level of dose from ionizing radiation and t h a t any detrimental

e f f e c t s on health produced

by

the radiation will be proportional t o the

dose equivalent delivered. The

EPA

policy utilized the best available

s c i e n t i f i c knowledge and assumed a l i n e a r , non-threshold relationship

between the magnitude of the radiation dose received and adverse health

e f f e c t s produced. The lack of information on e f f e c t s of low doses of

ionizing radiation caused the

EPA

t o choose a conservative method, using a

1

inear extrapolation from data f o r high doses (Cothern, 1981

)

.

The Environmental Protection Agency has s e t a l i m i t f o r man-made radio-

nuclides of

4

mrem per year. This corresponds to 20,000 pCi/l f o r tritium

or 8.0

p

Ci/l f o r strontium-90.

(~nvironmental Protection Agency, l976a).

Only communities with a population greater than 100,000 using a surface

water source a r e required to monitor f o r man-made radionuclides. None of

the systems in North Carolina exceed these l i m i t s ; and therefore, man-made

radionuclides a r e not monitored in North Carolina.

For naturally occurring radionuclides, the Environmental Protection

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(including radium-226,

b u t

excluding radon and t o t a l uranium), and 5 pCi/l

for combined radium-226 and radium-228 (Environmental Protection Agency,

1976a).

The

average dose t o bone from the continuous ingestion of water with

a radium-226 concentration of 5 pCi/l reaches an equilibrium value of 150

mrem per year. The radiotoxicity of radium-226 (an alpha p a r t i c l e emitter)

and radium-228 (a beta p a r t i c l e emitter) i s very similar when decay products

are considered, giving similar doses to bone f o r equal concentrations.

The estimated r i s k of death from bone cancer

(80

to 85 percent of

radium i s retained in bone material) and other forms of cancer such as

leukemia (approximately 15 percent of radium i s deposited in s o f t t i s s u e )

from consuming two 1 it e r s of drinking water per day containing

5

pCi/l of

radium i s 1

. 5

cancer cases per year per mi 11 ion persons exposed (Envi ron-

mental Protection Agency, 1

976b).

The maximum contaminant level f o r gross alpha p a r t i c l e a c t i v i t y i s

based on the radiotoxicity of other alpha particle-emitting contaminants

r e l a t i v e to radium. The 15 pCi/l gross alpha p a r t i c l e l i m i t (which includes

radium-226) i s based on the assumption t h a t i f the radium concentration

accounts f o r

5

pCi/l and the balance of the alpha p a r t i c l e a c t i v i t y i s due

t o the n e x t most r a d i o t o x i c

alpha particle-emitting chain, the t o t a l dose

t o

bone

would be equivalent t o l e s s than 6 pCi/l t o radium-226 (Environmental

Protection Agency, 1

976b).

The maximum contaminant level f o r gross alpha

p a r t i c l e a c t i v i t y excludes any uranium or radon t h a t may be present in the

sample. The monitoring of radon gas ('''~n),

with a r e l a t i v e l y short half-

l i f e of

3.8

days, in the large number of systems involved and with the

detailed sampling technique required would be expensive. The decision on

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EPA. Uranium i s a l s o n o t l i m i t e d i n d r i n k i n g w a t e r by t h e g r o s s alpha contaminant 1 i m i t , b u t t h e c r e a t i o n o f a t o t a l uranium s t a n d a r d (combined uranium-238 and uranium-234) i s p r e s e n t l y b e i n g considered. The EPA i s c u r r e n t l y g a t h e r i n g d a t a on t h e e f f i c i e n c y and c o s t o f uranium removal by means o f a n i o n exchange. T h i s w i l l form t h e b a s i s f o r t h e e v e n t u a l d e c i - s i o n as t o whether t o s e t a uranium l i m i t and t o make uranium m o n i t o r i n g mandatory (personal comnunication, C. R. Cothern, 1982).

I n a d d i t i o n t o t h e a c t u a l 1 im i t s o f a c t i v i t y o f r a d i o n u c l i d e s i n d r i n k i n g water, t h e s e q u e n t i a l d e t e r m i n a t i o n o f whether t o t e s t f o r a par-

t i c u l a r r a d i o n u c l i d e i s a l s o c o n t a i n e d i n t h e N a t i o n a l I n t e r i m P r i m a r y D r i n k i n g Water R e g u l a t i o n s (Environmental P r o t e c t i o n Agency, l 9 7 6 a ) ; see F i g u r e 1. The f i r s t s t e p i n d e t e r m i n i n g t h e c o n c e n t r a t i o n o f r a d i o n u c l i d e s i n d r i n k i n g w a t e r i s t h e measurement o f t h e gross a1 pha p a r t i c l e a c t i v i t y . I f t h e g r o s s a1 pha p a r t i c l e a c t i v i t y i s l e s s than 5 p C i / l

,

t h e w a t e r s u p p l y i s i n compliance and t h e a n a l y s i s need go no f u r t h e r . However, i f t h e gross alpha p a r t i c l e a c t i v i t y i s g r e a t e r t h a n 5 p C i / l , t h e a c t i v i t y o f Ra-226 must be determined. I f t h e c o n c e n t r a t i o n o f Ra-226 i s g r e a t e r t h a n 3 p C i / l , Ra-228 must then a l s o be analyzed. I f t h e t o t a l a c t i v i t y o f Ra-226 and Ra-228 exceeds 5 p C i / l , a v i o l a t i o n o f t h e maximum contaminant l e v e l f o r

radium e x i s t s . I f t h e gross alpha p a r t i c l e a c t i v i t y exceeds 15 p C i / l , a v i o l a t i o n o f t h e maximum contaminant 1 eve1 f o r g r o s s a1 pha p a r t i c l e a c t i v i t y e x i s t s . A l l measurements o f t h e g r o s s a l p h a p a r t i c l e a c t i v i t y a r e t o

exclude any a c t i v i t y f r o m radon and uranium b u t i n c l u d e radium-226 a c t i v i t y (Environmental P r o t e c t i o n Agency, l 9 7 6 a ) ; see F i g u r e 1.

(21)

b +

I MEASURE

GROSS ALPHA

N O ' J

IS ALPHA

-

' IS ALPHA

>

s

pCill

To

>

16 pCi/l

J

YES

I

I

MEASURE

Ra-226

I

I

MEASURE RADON & URANIUM MEASURE Ra-228

.

fa Ra-226 NO

PLUS Ra-228 '

'

>

6 pCl/I b

YES

t

I

IaALPHA

I

MINUS

I

COMPLIANCE

)

I

NON-COMPLIANC

YES

(22)

human heal t h (Environmental P r o t e c t i o n Agency, 1 976b). The a c t i v i t y l e v e l s o f r a d i o n u c l i d e s can be d i r e c t l y measured, and r a d i a t i o n doses can be c a b c u l a t e d u s i n g models; b u t t h e r e l a t i o n s h i p between doses t o humans and heal t h e f f e c t s a r e d e r i v e d from human e p i d e m i o l o g i c a l s t u d i e s and research i n v o l v i n g animals and o t h e r b i o l o g i c a l systems (Environmental P r o t e c t i o n Agency, 1376b).

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PROCEDURES

With the issuance of the Safe Drinking Water Act and the Primary

Drinking Water Regulations f o r Radioactivity, the

EPA

recognized the need

f o r

a comprehensive col 1 ection of analytical procedures f o r the measure-

ment of radionucl ides in drinking water. Considerations such as accuracy,

analytical cost, r e l i a b i l i t y and practical time limitations were used t o

s e l e c t these procedures.

The procedures were selected from numerous radio-

chemical methodologies and are used as the prescribed method of analysis.

Water samples were measured f o r gross alpha p a r t i c l e a c t i v i t y , radium-

226 and radium-228 using EPA' s Interim Radio1 ogi cal Method01 ogy f o r Drink-

ing Water (Environmental Protection Agency,

1

9 7 6 ~ ) . Uranium was measured

using the method "Microquantities of Uranium in Water by Fluorometry," as

specified by the American Society f o r Testing and Materials Annual Book of

ASTM

Standards, Water and Atmospheric Analysis

(ASTM,

1975) and analytical

techniques specified in Osmond and Cowart, 1976 (Osmond and Cowart, 1976).

Three measurements of uranium-234 and uranium-238 were made by Ms.

J .

Michel a t the University of South Carolina Geology Department Laboratories

using analytical techniques outlined in Osmond and Cowart (1976). All other

analyses followed procedures outlined

i n

the

EPA

and

ASTM

methods previously

mentioned and were performed a t the North Carolina State Laboratory of

P u b -

l i c Health by Ms. Shirley Bell. Annual composites of four consecutive

(24)

RESULTS AND

DISCUSSION

Natural Radioactivity in North Carolina Water Supplies

Gross Alpha and Radium Concentrations

- - - - -- -

Of the 2,089 systems analyzed, those

t h a t

exceeded the Safe Drinking

Water Act maximum contaminant level for gross alpha

and

radium concentra-

tions are l i s t e d in Tables

1 a n d 2 ,

respectively. The gross alpha values

do

not exclude uranium concentrations (as specified by the standard) because

these data were n o t available a t the time of t h i s study for many systems.

The highest data obtained were 80.7 pCi/l for gross alpha particle

activity ( f i v e times the l i m i t ) ,

1 7 . 2

pCi/l for radium-226,

22.7

pCi/l for

radium-228,

a n d

38.6 pCi/l for combined radium (over seven times the

1

imit).

Of the 2,089 supplies tested, 51 water systems or

2.4

percent of those sys-

tems tested were found to be in violation of federal and s t a t e standards

by

exceeding the maximum contaminant

1

eve1

s . Thi rty-nine systems or 1.9

percent of those systems tested

had

combined radium violations; an addi-

tional 12 systems or 0.6 percent

had

gross alpha violations

a n d 1 4

of these

systems or

0.7

percent

had b o t h

combined radium and gross alpha violations.

Thus, a total of

65

violations of the standards was observed

i n

North Caro-

lina between June 24,

1979,

the beginning of the monitoring program, and

August 1 , 1982. (For county distribution of violations, see Figure

2 . )

A

few systems

had

more than one analysis of the radiological content of

t h e i r water performed.

In these cases the higher analytical value was

l i s t e d . However, in these cases a l l of the system values exceeded federal

and s t a t e standards.

All

data are displayed with the counting error in pCi/l for

a 95-percent

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Table 1

GROSS ALPHA PARTICLE A C T I V I T Y OF THOSE SYSTEMS EXCEEDING FEDERAL AND STATE STANDARDS

*

System a l s o i n v i o l a t i o n

of

radium s t a n d a r d .

**Does not excl ude uranium.

(26)

T a b l e 2

No.

2 2 6 ~ a , 2 2 8 ~ a AND COMBINED Ra OF THOSE SYSTEMS EXCEEDING FEDEEAL AND STATE STANDARDS

System

1

Radium-226

I.D.

No. ( p ~ i / l i t e r ) ( p C i / l i Radium-228 t e r )

Combi ned Radi um ( p C i / l i t e r )

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(28)

disintegrations, there i s an e r r o r associated with any measured count of

these disintegrations. The variabi 1 i ty of these measurements

i s

indicated

by the displayed counting error. Additional information on counting e r r o r

i s covered by Krieger and Mhittaker's (1980) publ ication, "Prescribed Pro-

cedures f o r Measurement of Radioactivity in Drinking Water."

The average concentration of gross alpha p a r t i c l e a c t i v i t y f o r those

systems in violation of federal and s t a t e standards was 29.5 pCi/l. The

amount of whole body dose or organ dose cannot be estimated from the gross

alpha p a r t i c l e a c t i v i t y , due to the lack of knowledge of specific radio-

nuclide. The average level of radium f o r those systems in violation of the

standard was

1 2 . 2

pCi/l which gives a human bone dose of

365

mrem/year and

using the

EPA

l i n e a r extrapolation f o r dose vs. e f f e c t may cause

3.6

deaths

per year from cancer per mil 1 ion people continuously exposed (Environmental

Protection Agency, l976b). A t the present r a t e of occurrence of water sys-

tems which exceed the

5

pCi/l radium standard (1.9 percent of those systems

t e s t e d ) , within the State of North Carolina using ground water (present popu-

lation

3

million), one person may die from cancer every

4.8

years due t o the

amount of radium ingested in drinking water.

T h i s

r a t e

does

not

t a k e

into

account other radionuclides

i n

drinking water which the present regulations

do not address such as radon and uranium.

These levels of exposure t o radionuclides in drinking water will remain

i f nothing i s dcne t o change the concentrations of the radioactive contami-

nants o r the source of water. When a water system i s found t o have levels

of gross alpha p a r t i c l e a c t i v i t y o r combined radium a c t i v i t y which exceed

the standards, the system owner i s responsible f o r notifying the North Caro-

l ina Department of Human Resources

( D H R ) ,

notifying the households which

(29)

newspaper a n o t i f i c a t i o n t o t h e p u b l i c f o r t h r e e c o n s e c u t i v e days; n o t i f y - i n g a r a d i o and t e l e v i s i o n s t a t i o n s e r v i n g t h e area; s u b m i t t i n g a p l a n o f a c t i o n f o r c o r r e c t i n g t h e problem i n c l u d i n g a t i m e t a b l e f o r c o r r e c t i v e

a c t i o n ; and r e p e a t i n g q u a r t e r l y t h e p u b l i c n o t i c e and m o n i t o r i n g o f t h e w a t e r system u n t i l two q u a r t e r l y samples p r o v e t h a t t h e problem no l o n g e r e x i s t s (Environmental P r o t e c t i o n Agency, 1976a).

Radium-228 t o Radium-226 R a t i o s

Under p r e i e n t r e g u l a t i o n s t h e a n a l y s i s o f radium-228 i s o n l y performed i f t h e c o n c e n t r a t i o n o f radium-226 i s i n excess o f 3 p C i / l . As M i c h e l and Moore ( 1 979) p o i n t e d o u t , t h e r a t i o o f radium-228 t o radium-226 ( 2 2 8 ~ a / 2 2 6 ~ a ) i s n o t c o n s t a n t and can v a r y by as much as a f a c t o r o f 3. T h i s v a r i a b i 1 i t y , t h e r e f o r e , makes i t p o s s i b l e f o r a system w i t h l a r g e amounts o f radium-228 t o exceed t h e combined radium l i m i t o f 5 p C i / l b u t n o t t o be i d e n t i f i e d as such because t h e l e v e l o f radium-226 d i d n o t exceed 3 p C i / l (Michel and Moore, 1979).

T h i s v a r i a b i l i t y i s a l s o e v i d e n t i n t h e r a d i u n d a t a o f T a b l e 2, which has a maximum 2 2 8 ~ a / 2 2 6 ~ a r a t i o o f 2.6. Table 3 1 is t s t h e 2 2 8 ~ a / 2 2 6 ~ a r a t i o s o f t h e radium data ( t a k e n from Table 2). A s t a t i s t i c a l e x a m i n a t i o n o f t h e 2 2 8 ~ a / 2 2 6 ~ a r a t i o s y i e l d e d a mean o f 0.65 and a s t a n d a r d d e v i a t i o n o f 0.63, an i n d i c a t i o n o f h i g h v a r i a b i l i t y . O f t h e 39 systems examined, 69 p e r c e n t o f t h e systems had 2 2 8 ~ a / 2 2 6 ~ a l e s s t h a n one. I n t h e s e cases t h e c o n t e n t o f radium-226 was g r e a t e r t h a n t h e c o n t e n t o f radium-228, which sup- p o r t s t h e p r e s e n t procedure. However, 31 p e r c e n t o f t h e systems had

(30)

Table 3

228~,/226~, RATIO OF THOSE SYSTEMS EXCEEDING THE RADIUM STANDARD

(31)

Thus, in order to be sure t h a t the l i m i t of

5

pCi/l for combined

radium i s not exceeded, radium-228 would have t o be measured regardless of

the concentration of radium-226, i f the gross alpha p a r t i c l e a c t i v i t y exceeds

5

pCi/l

.

Consideration of the cost-benefi

t aspects of radium-228 monitoring

i s needed.

Uranium Concentrations

A

limited amount of data was obtained on the t o t a l uranium concentra-

tion of twenty-three water supply systems in which the gross alpha concen-

t r a t i o n exceeded 15 pCi/l (see Table

4 ) .

These data are primarily f o r single

samples collected from single wells rather than annual composites of four

quarterly samples from the system. Thus, they generally are not f o r analyses

of the same samples from which the radium data shown

i n

Figure

2

were

obtained. The t o t a l uranium content consists of the combined concentrations

of uranium-238 and uranium-234.

In those samples analyzed, the average level

of uranium a c t i v i t y was

26.7

pCi/l.

No

regulatory standard currently e x i s t s

for the concentration of uranium i n drinking water.

Uranium i s chemically toxic as well as radiologically toxic. The

National Academy of Sciences has recornended t o the

EPA t h a t

a one-day

a n d

seven-day suggested limit f o r uranium of

3.5

mg/liter (2300 p C i / l i t e r ) and

0.2 mg/l i t e r (140 p C i / l i t e r ) , respectively, be used based on chemical toxi-

c i t y only (Lappenbusch, 1979).

I t i s the

j u d g m e n t

of the Environmental Protection Aoency a t t h i s time

t h a t

radiotoxicity should be given priority. The level

o f

radiotoxicity of

uranium i s best calculated by comparing

23%

and

2 3 4 ~

with 2 2 6 ~ a ,

since a l l

-

of these radionuclides are bone seekers. I t i s the consensus

o f

EPA's

pro-

gram t h a t 20 pCi/day o r 10 pCi/l of uranium would r e s u l t in

a dose r a t e to

(32)

Table 4

TOTAL URANIUM CONTENT ( 2 3 4 ~ AND 2 3 8 ~ )

No

.

System I d e n t i f i c a t i o n Number. T o t a l Uranium

I

* A n a l y s i s performed a t t h e U n i v e r s i t y o f South Carol i n a Depart- ment o f Geology L a b o r a o t r i e s .

(33)

f o r radium l i m i t s t h e bone dose r a t e t o 150 mremlyear, u r a n i u m ' s e f f e c t on t h e same organ system s h o u l d n o t exceed t h i s l e v e l . T h i s o p i n i o n i s a l s o shared by t h e EPA (Lappenbusch, 1979).

The h i g h e s t d a t a v a l u e o b t a i n e d was 277 p C i / l o f t o t a l uranium o r 28 t i m e s t h e 10 p C i / l l i m i t discussed. T h i s c o n c e n t r a t i o n o f uranium would y i e l d a bone dose o f 4200 mrem p e r y e a r . T h i s h i g h l e v e l o f uranium demon-

s t r a t e s t h e v u l n e r a b i 1 i t y o f p r e s e n t standards. Since uranium i s o m i t t e d from b e i n g one o f t h e c o n s t i t u e n t s o f gross a l p h a a c t i v i t y , d r i n k i n g w a t e r c o u l d be l e g a l l y s u p p l i e d c o n t a i n i n g 277 p C i / l o f uranium p r o v i d e d i t does n o t exceed standards f o r o t h e r r a d i o n u c l i d e s . The average l e v e l o f uranium was 26.7 p C i / l and would produce a bone dose o f 391 mrem p e r y e a r .

From t h e d a t a o b t a i n e d f o r systems exceeding standards o r suggested standards, t h e average and h i g h e s t c o n c e n t r a t i o n s o f gross a l p h a p a r t i c l e a c t i v i t y , combined radium and t o t a l uranium, a r e l i s t e d i n Table 5. These d a t a g i v e an i n d i c a t i o n o f t h e need f o r c o n s i d e r a t i o n o f a uranium standard. The small sample s i z e t e s t e d f o r uranium prevented t h e e x t r a p o l a t i o n o f t h e p e r c e n t o f systems i n N o r t h C a r o l i n a h a v i n g uranium c o n c e n t r a t i o n s i n excess o f 10 p C i / l .

An e x a m i n a t i o n was made o f t h e c o r r e l a t i o n e x i s t i n g between concentra- t i o n s o f radium-226 and t o t a l uranium. T o t a l uranium i s made up o f uranium- 238 and uranium-234, which a r e b o t h i n t h e uranium s e r i e s , t h e same s e r i e s as radium-226. Uranium d a t a were a v a i l a b l e f o r e i g h t w a t e r systems t h a t exceeded t h e r a d i u m standard. These measurements were p l o t t e d , and a l i n e a r r e g r e s s i o n a n a l y s i s was performed (see Table 6 and F i g u r e 3 ) . No c o r r e l a t i o n was found between c o n c e n t r a t i o n o f radium-226 and t o t a l uranium.

Treatment o f Water f o r Removal o f R a d i o n u c l i d e s

- - -

From t h e d a t a l i s t e d i n Table 2 we can a s c e r t a i n t h a t s i g n i f i c a n t l e v e l s o f radium e x i s t i n ground water. V i o l a t i o n s f o r exceeding t h e radium l i m i t

(34)

T a b l e 5

LISTING* OF THE AVERAGE AND HIGHEST CONCENTRATIONS OF GROSS ALPHA PARTICLE ACTIVITY, COMBINED RADIUM AND TOTAL

URANIUM AND THEIR STANDARDS (EXISTING AND DISCUSSED)

Gross Alpha

*For systems exceeding standards. L i m i t ( p C i / l )

Average ( p C i / l ) F a c t o r t i m e s l i m i t H i g h ( p C i / l )

F a c t o r t i m e s l i m i t

* * E q u i v a l e n t t o radium 1 i m i t.

Radi urn

Table 6

LISTING OF RADIUM-226 AND TOTAL URANIUM

U r a n i urn 15 29.5 2.0 80.7 5.4 No. 1 2 3 4 5 6 7 8

System I. D. No. 02 35 119 03 26 214 03 51 114 03 83 127 04 33 108 04 64 045 04 96 117 04 33 035

5 12.2

2.4 38.6 7.7

T o t a l Uranium 49.4 _+ 4.6

I-

1 O** 26.7

2.7 277

27.7

Average Ra = 8.21

Average Uranium = 10.86

Y i n t e r c e p t = 18.63

Slope =

-

0.95

(35)
(36)

have been issued, and a few N o r t h C a r o l i n a w a t e r systems have found a l t e r - n a t e sources o f w a t e r . However, s u c c e s s f u l t r e a t m e n t o f w a t e r c o n t a i n i n g h i g h l e v e l s o f radium has n o t been achieved. The Environmental P r o t e c t i o n Agency (1 977) has recommended r a d i um removal techniques o f 1 ime o r 1 ime-soda s o f t e n i n g ( p r e c i p i t a t i v e s o f t e n i n g ) , i o n exchange ( c a t i o n exchange) and r e v e r s e osmosis. E x t e n s i v e examples o f radium removal f o r w a t e r systems have been pub1 i s h e d ( E n v i r o n f i e n t a l P r o t e c t i o n Agency, 1977; B r i n c k , e t a1

.

,

1976; S i n g l e y , e t a l . , 1977; Schliekelman, 1976; Bennett, e t a l . , 1976).

S o l u b l e radium, a d i v a l e n t a l k a l i n e e a r t h metal c a t i o n s i m i l a r t o c a l - cium and magnesium, i s removed a l o n g w i t h o t h e r forms o f hardness by a p r e - c i p i t a t i v e s o f t e n i n g process (see F i g u r e 4, T o t a l Hardness Removal as a F u n c t i o n o f Raw Water Radium C o n t e n t ) . The lime-soda process i s a p r e c i p i - t a t i v e s o f t e n i n g process which uses t h e a d d i t i o n o f 1 ime (CaO-quick1 ime, o r Ca(OH)2 s l a t e d o r h y d r a t e d l i m e ) t o c o n v e r t t h e sodium b i c a r b o n a t e s o f c a l c i u m and magnesium i n t o i n s o l u b l e c a l c i u m carbonate and magnesium hydroxide. I n a d d i t i o n t o t h i s carbonate hardness, c a l c i u m and magnesium a s s o c i a t e d w i t h t h e s u l f a t e , c h l o r i d e o r o t h e r i o n s o f non-carbonate hard- ness a r e removed by t h e a d d i t i o n o f b o t h l i m e and soda ash (Na2c03) which p r o v i d e s t h e carbonate i o n necessary f o r f o r m a t i o n o f c a l c i u m carbonate. P r e c i p i t a t i v e s o f t e n i n g i s u s u a l l y employed t o remove hardness and o t h e r i m p u r i t i e s f r o m s u r f a c e waters. The chemicals added i n t h e r a p i d - m i x chamber a r e a l l o w e d t o f o r m a f l o c i n t h e f l o c c u l a t i o n chamber and f i n a l l y s e t t l e o u t i n t h e s e t t l i n g chamber (see F i g u r e 5 ) . P l a n t e f f i c i e n c y of hardness removal w i l l vary. I n a s t u d y performed by t h e Environmental Pro- t e c t i o n Agency, radium rerroval e f f i c i e n c y averaged 80 p e r c e n t (Sing1 ey, e t a l . , 1977).

(37)

16,Q

20.0

30;O

40.0

Raw Water Radium

pCi/l

(38)

LIMR AND/OR

8 0 0 4 A S H

RAW WATRR

1

I M f L U R N T

S E l T LlNO TANK S A N D F I L T E R

S l U D O E

-

p r ~ o n v W A ~ ~ R 1 C f l U R N l

S O L I D S DY t % O ? TOTAL 10 C L E A R

W R l O H T F L O W DY V O l U M l W a l t

(39)

The level of radium in surface waters i s normally low, unless uranium o r

phosphate mining a c t i v i t i e s are discharging effluents to a water course.

No such occurrence upstream t o a public water supply has been documented

t o e x i s t in North Carolina. However, i f precipitative softening i s used

f o r the removal of radium, the disposal of f i l t e r backwash water poses no

particular problem since the a c t i v i t y levels in the waste stream have been

found t o be only s l i g h t l y higher than levels found in the raw water. The

majority of the radium a c t i v i t y removed appears to remain in the s e t t l i n g

chamber waste sludge. The a c t i v i t y in the dry sludge approaches a level of

5

10 pCi/Kg, and special considerations must be given to safe disposal of

the contaminated sludge (Singley, e t a1

.

,

1977), such as shipment to a low-

1 eve1 radioactive waste burial ground.

Water softening by the ion-exchange process depends upon the a b i l i t y

of c e r t a i n insoluble substances to exchange cations with other cations dis-

solved in water. When hard water i s passed through a sodium cation exchanger,

the calcium and magnesium in the hard water are replaced by sodium from the

exchanger. After a l l of the readily replaceable sodium has been exhausted

f o r calcium and magnesium from the hard water, the exhausted cation exchanger

can be regenerated with a solution of sodium chloride.

I n

the regeneration

process, the calcium and magnesium

o f

the exhausted cation exchanger are

replaced with a fresh supply of sodium from the regenerating brine solution.

The regenerated exchanger i s then washed with treated water t o f r e e any

excess s a l t and i s ready to be used again t o soften raw water.

Many material s with cation exchange properties such as polystyrene-

type resins and mineral greensands a r e used f o r exchange media.

Small water

systems can u t i l i z e t h i s means of treatment which can remove radium

u p

t o a

95-

percent efficiency leve1,as well as hardness and trace amounts of heavy

(40)

automatic o p e r a t i o n o f t h e t r e a t m e n t system (see F i g u r e 6 ) , making t h i s form o f t r e a t m e n t i d e a l f o r use by an u n t r a i n e d o p e r a t o r .

The repeated success o f radium removal demonstrated b y S i n g l e y , e t a l . , (1977) by means o f c a t i o n exchange makes t h i s an a t t r a c t i v e technique. Approximately 9 p e r c e n t o f t h e radium a c t i v i t y remains i n t h e exchange medium; t h e remainder appears i n t h e regenerant b r i n e e f f l u e n t a t l e v e l s approaching 1,000 p C i / l . Disposal methods f o r spent b r i n e may more o f t e n be l i m i t e d by c o n s i d e r a t i o n s o f s a l i n i t y r a t h e r t h a n rgdium a c t i v i t y l e v e l s

( S i n g l e y , e t a l . , 1977). However, i n N o r t h C a r o l i n a t h e r e a r e no examples o f s u c c e s s f u l radium removal.

Manganese o x i d e suspensions have been shown t o absorb l a r g e q u a n t i t i e s of v a r i o u s aqueous metals (Murray, e t a1

.

,

1968). Radi urn e x t r a c t i o n s t u d i e s

(Moore, 1975 and 1982), performed by Moore on w e l l w a t e r h a v i n g e l e v a t e d l e v e l s o f radium ( 2 2 6 ~ a ) measured a t a p p r o x i m a t e l y 115 p C i / l r e s u l t e d i n removal e f f i c i e n c y r a t e s o f 95 t o 87 p e r c e n t u s i n g 40 grams o f Mn f i b e r s . A c r y l i c f i b e r impregnated w i t h 12 t o 15 p e r c e n t manganese a c t e d as a c a t i o n a d s o r p t i o n f i 1 t e r i n t h e removal o f radium c a t i o n i c r a d i o n u c l i d e (Moore, 1982). I n t h i s s t u d y Moore e s t i m a t e d f i l t e r p r e p a r a t i o n c o s t f o r one k i l o - gram o f manganese f i l t e r media t o be f i f t e e n d o l l a r s . T h i s amount o f f i l t e r media c o u l d t r e a t 10,000 l i t e r s o f water w h i l e removing 100 p C i / l o f radium

(Moore, 1975) o r 2.5 m i l l i o n l i t e r s o f w a t e r removing 12 p C i / l

,

t h e average l e v e l o f radium found i n those systems exceeding t h e s t a n d a r d i n N o r t h Caro- l i n a . A one-kilogram f i l t e r would be capable o f p r o v i d i n g adequate t r e a t - ment f o r an average f a m i l y f o r a number o f y e a r s a t a c o s t o f $10 p e r f a m i l y p e r y e a r and, t h e r e f o r e , i s a p o t e n t i a l c o s t - e f f e c t i v e means o f radium

removal f o r p u b l i c water systems. T h i s i s , however, a new technology.

(41)

METE

7

1

1

WASH-WATER I O N

-

E X C M A N O E

U N I T

I

E X C H A N G E M A T L R I A L

COLLECTOR

PRESSURE WATER

L

B E D

(42)

and c o n s i s t e n t l y documented t o remove radium from p u b l i c w a t e r systems t o a 1 eve1 be1 ow t h e Safe D r i n k i n g Water A c t Standard (Environmental P r o t e c t i o n Agency, 1976a). U n t i l f u r t h e r s t u d y has proved t h i s method successful and a source o f prepared f i l t e r s i s a v a i l a b l e t o t h e pub1 i c , radium removal w i t h manganese f i l t e r s i s n o t a v i a b l e form o f t r e a t m e n t .

The l a c k o f a d r i n k i n g w a t e r standard f o r uranium has been d i r e c t l y a t t r i b u t e d t o t h e l a c k o f documented i n s t a n c e s i n which i t was s u c c e s s f u l l y removed (personal c o m u n i c a t i o n , C. R i c h a r d Cothern, 1982). The valence s t a t e s o f uranium ( 2 3 8 ~ , 2 3 5 ~ , 2 3 4 ~ ) a r e +2, +3, +4 and +6 and a r e most commonly found i n t h e hexavalent and t e t r a v a l e n t s t a t e s (Cothern and

Lappenbusch, 1983). I t has a tendency t o form u r a n y l d i - and t r i - c a r b o n a t e anions which a r e b o t h s o l u b l e and mobile. I n a h y d r o l o g i c a l l y r e d u c i n g c o n d i t i o n t h e uranium would n o t be m o b i l e and, thus, would n o t be a problem u n t i l decaying t o 2 3 4 ~ h o r 2 3 0 ~ h (Osmond and Cowart, 1976).

Under l a b o r a t o r y c o n d i t i o n s a n i o n exchange has been s u c c e s s f u l l y

employed as t h e p r e f e r r e d means o f s e p a r a t i o n o f uranium from w a t e r and o t h e r r a d i o n u c l i d e s (Osmond and Cowart, 1976). There i s no reason t o b e l i e v e t h a t anion exchange would n o t a l s o work f o r l a r g e - s c a l e d r i n k i n g w a t e r s u p p l i e s , as i t has f o r t h e removal of o t h e r anions i n d r i n k i n g water s u p p l i e s , and r a d i o n u c l id e s i n n u c l e a r r e a c t o r cool a n t process waters (Stranb, 1964).

The Environmental P r o t e c t i o n Agency i s c o l l e c t i n g d a t a on uranium

. removal e f f i c i e n c y r a t e s (personal comnunication, C. Richard Cothern, l 9 8 Z ) , b u t a t t h e p r e s e n t t i m e no p u b l i c a t i o n s o f r e s u l t s a r e a v a i l a b l e .

In a d d i -

t i o n , due t o t h e n a t u r e o f a n i o n exchange and t h e s t r o n g a c i d r e s i n r e j u v e - n a t i o n requirements i n v o l v e d , i t i s n o t expected t o be a p r a c t i c a l a1 t e r n a -

(43)

water systems with high levels of uranium, there will be no need t o create

innovative methods of uranium removal.

Studies by Aldrich, e t a1

.

,

(1 975) and Sasser and Watson (1 977) have

shown t h a t high levels of radon-222 in ground-water supplies a r e not uncom-

mon in North Carolina. Radon-222, a f a i r l y insoluble gas, can be e a s i l y

removed by aeration. The radioactive gas can then

be

vented t o the atmos-

phere.

However, no standard e x i s t s to l i m i t the concentration of radon-222

in drinking water; and therefore, l i t t l e i s expected t o be done f o r the

(44)

BIBLIOGRAPHY

Aldrich, L. K . , M. K. S a s s e r , and D. A. Conners. "Evaluation of Radon Con- c e n t r a t i o n s i n North Carol i n a Ground Water Suppl i e s . " N . C . Department

of Human Resources, Radiation Protection Branch, Raleigh, NC, 1975.

American Society f o r Testing and Materials (ASTM). Annual Book of ASTM Standards, Water and Atmospheric Analysis. P a r t 31, 1975.

Bennett, D. L . , C. R. Bell and I . M. Markwood. "Determination of Radium Removal E f f i c i e n c i e s i n I l l i n o i s Water Supply Treatment Processes." Environmental P r o t e c t i o n Agency ORP/TAD-76-2, 1976.

Brinck, W. L . , R. J . Schliekelman, D. L. Bennett, C . R. B e l l , and I . M . Markwood. "Determination of Radium Removal E f f i c i e n c i e s i n Water

Treatment Processes. "Environmental P r ~ t e c t i o n Agency ORP/TAD-76-5, 1976.

Choppin, G . R . and J . Rydberg. Nuclear Chemistry Theory and Application. Tal l a h a s s e e , FL: Florida S t a t e University, 1980.

Cothern,

C . R. " R a d i o a c t i v i t y i n Drinking Water." Environmental P r o t e c t i o n Agency, EPA-570/9-81-002, 1981.

Cothern, C. R . Personal communication o f M . Y . Menetrez, August 1982.

Cothern, C. R. and W.

L .

Lappenbusch. "Occurrence o f Uranium i n Drinking Water i n t h e U. 5." Health Physics, 45, 1963, pp. 88-89.

Dolphin, G . W. and I . S. Eve. "Dosimetry o f t h e G a s t r o i n t e s t i n a l T r a c t . " Health Physics, 12, 1966, pp. 163-172.

Dougherty, T. F. and C . W. Mays. "Bone Cancer Induced by I n t e r n a l l y

Deposited

Emitters

i n Beagles, Radiation Induced Cancer." I n t e r n a t i o n a l Atomic Energy Agency

-

SM-118:3, 1969.

Duncan, D. L . , T. F. G e s e l l , and R. H. Johnson. "Radon-222 i n Potable Water.'' Paper 19, Health Physics S o c i e t y , 10th Midyear Topical Symposium:

Natural R a d i o a c t i v i t y i n Man's Environment, Saratoga Springs, N Y , 1976.

Environmental P r o t e c t i o n Agency. "Drinking Water Regulation, Radionuclides." Federal R e g i s t e r T i t l e 40, P a r t 141, 1976a.

Environmental P r o t e c t i o n Agency. "National Interim Primary Drinking Water Regulations." EPA-570/9-76-003, 1976b.

Envi ronmental P r o t e c t i o n Agency, Interim Radiological Methodology f o r D r i n k - ing Water, 600/4-75-008, 1976c.

(45)

Evans,

R.

D. "Engineers Guide t o t h e Elementary Behavior o f Radon Daughters." H e a l t h Physics, 17, 1969, pp. 229-252.

Hems, G. "Acceptable C o n c e n t r a t i o n o f Radon i n D r i n k i n g Water." A i r Water P o l l u t i o n , 10, 1966, p. 465.

I n t e r n a t i o n a l Commission on R a d i a t i o n P r o t e c t i o n . "Report o f Committee I 1

on P e r m i s s i b l e Dose f o r I n t e r n a l R a d i a t i o n . " ICRP 2, 1959.

I n t e r n a t i o n a l Commission o f R a d i a t i o n P r o t e c t i o n . " A l k a l i n e E a r t h Metabolism i n A d u l t Man." ICRP 20, 1972.

I n t e r n a t i o n a l Commission on R a d i a t i o n P r o t e c t i o n . "Report o f t h e Task Group on Reference Man." ICRP 23, 1975.

I n t e r n a t i o n a l Commission o f R a d i a t i o n P r o t e c t i o n . " L i m i t s f o r I n t a k e s o f Radionuclides by Workers." 2, No. 3/4, 1979.

K r i e g e r , H. L. and W h i t t a k e r . " P r e s c r i b e d Procedures f o r Measurement o f R a d i o a c t i v i t y i n D r i n k i n g Water. I' Environmental P r o t e c t i o n Agency EPA-600/4-80-032, 1980.

Lappenbusch, W. L. L e t t e r from W. L. Lappenbusch, A c t i n g C h i e f , H e a l t h E f f e c t s Branch, Envi ronmental P r o t e c t i o n Agency, t o F. A. T a y l o r , E x e c u t i v e D i r e c t o r , Colorado Department o f Heal t h , 1979.

Lee, R. D. and J. E. Watson. "An Assessment o f Radium i n Selected N o r t h

C a r o l i n a D r i n k i n g Water Suppl i e s .

"

H e a l t h Physics, 37, 1979, pp. 777-779. Marmier, P. and E. Sheldon. Physics o f N u c l e i and P a r t i c l e s . Z u r i c h ,

S w i t z e r l a n d : Federal I n s t i t u t e o f Technology, 1969.

M i c h e l , J. and W. S. Moore. " 2 2 8 ~ a and 2 2 6 ~ a Content o f Groundwater i n Fa1 1 L i n e A q u i f e r s . " H e a l t h Physics, 38, 1979, pp. 663-67.

Moore, W. S. "Radium Removal f r o m D r i n k i n g Water," Nature, Vol

.

253, No. 5489, 262-263, January 1975.

Moore, W. S. "Preparing Manganese Oxide Coated A c r y l i c F i b e r and A r t i c l e Therefrom,' U. S. P a t e n t , 4,k087,583, May 1982.

Murray, D. J., T. W. Healy and D. Fuerstenau. "The A d s o r p t i o n o f Aqueous Metal on C o l l o i d a l Hydrous Manganese Oxide." A d s o r p t i o n f r o m Aqueous S o l u t i o n , Adv. i n Chem., S e r i e s 79, American Chemical S o c i e t y , Wash- i n g t o n , DC, 1968.

N a t i o n a l Counci 1 on R a d i a t i o n P r o t e c t i o n . "Maximum P e r m i s s i b l e Amounts o f Radioisotopes i n t h e Human Body and Maximum P e r m i s s i b l e C o n c e n t r a t i o n i n A i r and Water." N a t i o n a l Bureau o f Standards Handbook, 52, 1953. N a t i o n a l Council on R a d i a t i o n P r o t e c t i o n . "Maximum P e r m i s s i b l e Body Burdens

(46)

N a t i o n a l C o u n c i l f o r R a d i a t i o n P r o t e c t i o n . " N a t i o n a l Background R a d i a t i o n i n t h e U n i t e d S t a t e s . "

NCRP

45, 1976.

Osmond, J. K. and J . B. Cowart. "The Theory and Uses o f N a t u r a l Uranium I s o t o p i c V a r i a t i o n s i n Hydrology." Atomic Energy Review, 14, 1976, p. 4.

Pub1 i c H e a l t h Services. R a d i o l o g i c a l H e a l t h Handbook. R o c k v i l l e , MD: Con- sumer P r o t e c t i o n and Environmental H e a l t h Service, 1970.

Sasser, M. K. and J . E. Watson. "An E v a l u a t i o n o f t h e Radon C o n c e n t r a t i o n i n N o r t h C a r o l i n a Ground Water S u p p l i e s . " H e a l t h Physics, 34, 1977, pp. 667-671.

Schliekelman, R. J . " D e t e r m i n a t i o n o f Radium Removal E f f i c i e n c i e s i n Iowa Water Supply Treatment Processes." Environmental P r o t e c t i o n Agency ORP/TAD-76-1, 1976.

S i n g l e y , J . E., B. A. Beaudet, W. E. B o l c h and J. F. Palmer. "Costs o f Radium Removal f r o m P o t a b l e Water Suppl i e s .

"

Environmental P r o t e c t i o n Agency EPA-600/2-77-073, 1977.

S t r a i n , C. D. and J. E. Watson. "An E v a l u a t i o n o f Radium-226 and Radon-222 C o n c e n t r a t i o n i n Ground and Surface Water Near a Phosphate M i n i n g and M a n u f a c t u r i n g F a c i 1 i ty." H e a l t h Physics, 37, 1979, pp. 779-783.

Stranb, C. P. "Low-level R a d i o a c t i v e Wastes." U n i t e d S t a t e s Atomic Energy Commission 64-60034, 1964.

Task Group on Lung Dynamics. " D e p o s i t i o n and R e t e n t i o n Models f o r I n t e r n a l Dosimetry o f t h e Human R e s p i r a t o r y T r a c t . " H e a l t h Physics, 12, 1966, pp. 773-207.

Figure

Figure 1. Flow Chart f o r  Gross Alpha Particle Activity and Radium Monitoring
Table 1
Table 2
228~,/226~, Table 3 RATIO OF THOSE
+7

References

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