71-4934

ARMITAGE, Donald Bruce, 1941-THE DETERMINATION AND DISTRIBUTION OFVARIOUS TRACE ELEMENTS IN NATURAL WATERS BYX-RAY FLUORESCENCE SPECTROSCOPY.

University of Hawaii, Ph.D., 1970Chemistry, analytical

University Microfilms, Inc., Ann Arbor, Michigan

MICROFILMED EXACTLY AS RECEIVEDTHIS DISSERTATION HAS BEEN

THE DETERMINATION AND DISTRIBUTION OF

VARIOUS TRACE ELEMENTS IN NATURAL WATERS

BY X-RAY FLUORESCENCE SPECTROSCOPY

A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THEUNIVERSITY OF HAWAII IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY

IN CHEMISTRY

MAY 1970

By

Donald Bruce Armitage

Dissertation Committee:

Harry Zeitlin, ChairmanGeorge AndermannRobert A. DuceJohn J. NaughtonSidney J. Townsley

)

ii

ABSTRACT

A method was developed for the analysis, consecutively, of six

trace metals uranium, copper, nickel, cobalt, iron, and manganese in a

sample of fresh water and sea water through a combination of solvent

extraction with an 8-hydroxy quinoline-chloroform mixture and X-ray

fluorescence spectrometry. The primary concentration step which may be

carried out on board ship requires only three reagents and minimal

equipment, thus reducing the risk of contamination and chemical changes

due to storage. In addition, the method is nondestructive and extracted

samples evaporated on filter paper may be stored for future reference.

A pr~cision of 10% or better was obtained for the six elements with a

sample volume of 500 ml.

The analysis was applied to sea water and fresh water samples

obtained from various sources.

Coastal sea water trace element content was found to be lower than

that from mid-ocean. What appears to be significant differences in the

trace element levels were found in the water masses studied but little

variation with latitude was detected. Several of the elements, notably

uranium, displayed an increase in concentration with depth.

Examination of fresh water samples indicated that biological

activity is related to the extractable trace metal content in that

increased activity was accompanied by higher content or trace metals.

This view has as yet not been substantiated by biological studies.

Other samples showed evidence of differences which may be associated

with the water source and pollution.

TABLE OF CONTENTS

ABSTRACT •

LIST OF TABLES •

LIST OF ILLUSTRATIONS

INTRODUCTION •

EXPERIMENTAL •

Preliminary Studies •Final Analytical Method •

iii

ii

iv

vi

1

8

812

A.B.C.D.

Chemicals and ApparatusPreparation of Standards and Standard Curves •ProcedureDiscussion of Procedure

12132124

RESULTS AND CONCLUSIONS

Sea Hater DataFresh Water Data

SUMMARY

APPENDIX I. Method Using Dithizone-Ce11u1oseAcetate Pellets •

APPENDIX II. Calculation of Critical Depth for ChromiumX-Ray Radiation in the CelluloseAcetate Pellets •

APPENDIX III. Neutron Activation Detection Limits •

BIBLIOGRAPHY •

36

4061

68

70

71

73

76

Table

iv

LIST OF TABLES

I COMPARISON OF DETECTION LIMITS FOR X-RAYFLUORESCENCE, ATOMIC ABSORPTION SPECTROMETRY,AND NEUTRON ACTIVATION ANALYSIS • • • • • • • • • • • 0 10

II

III

IV

V

COMPOUNDS AND AMOUNTS USED IN PREPARATIONOF PRIMARY STANDARDS •• • • • • • • • • • • •

EXTRACTION EFFICIENCY OF THE 8-HQ-CHC13 SYSTEMFOR SPIKED SEA WATER SAMPLES • • • • • • • • •

EXTRACTION EFFICIENCY OF THE 8-HQ-CHC13 SYSTEMFOR SPIKED DEIONIZED WATER SAMPLES •• •

RELATIONSHIP OF SAMPLE VOLUME TO PERCENTEXTRACTION EFFICIENCY OF THE 8-HQ-CHC13 SYSTEM

· . . . . .4 • • • • •

· . . . . .

· . . . . .

14

25

26

27

VI RELATIONSHIP BETWEEN SAMPLE VOLUME AND PERCENTEXTRACTED BY EACH EXTRACTION STEP (8-HQ IS ADDED­IN THE FIRST AND THIRD STEPS) • • • • • • • • • • 28

VII

VIII

IX

X

XI

EFFECT OF TIME DELAY AFTER ADDITION OF 8-HQON EXTRACTION EFFICIENCY (PERCENT) ••••

PRECISION IN J.lG AND % FOR THE EXTRACTION METHODBASED ON EVAPORATED AND EXTRACTED STANDARDSFOR MAXIMUM AND MINIMUM AMOUNTS ANALYZED.AVERAGE PRECISION OF THE ACTUAL SEA WATER ANDFP~SH WATER ANALYSIS •• • • • • • • • • • •

A COMPARISON OF DATA FROM SEA WATER ANALYSES

VARIATION OF TRACE ELEMENT CONCENTRATION (j.1g/1)WITH POSITION (160 0 W) • • • • • • • • • • • • •

VARIATION OF TRACE ELEMENT CONCENTRATION (j.1g/1)WITH POSITION (125 OW) • • • • • • • • • • • • •

· . . . . .

· . . . . .

29

37

39

41

42

XII RESULTS OF SEA WATER ANALYSES (CONCENTRATION j.1g/1) 43

XII VARIATION OF TRACE ELEMENT CONCENTRATIONWITH DEPTH (160 0 W) ••••••••••• · . . . . . . . . 50

XIV VARIATION OF TRACE ELEMENT CONCENTRATIONWITH DEPTH (125 OW) ••••••••••• · . . . . . . . • 51

xv VARIATION CF,~RACE ELEMENT CONCENTRATIONWITH RESPECT TO WATER MASS (160 0 W) · . . . . . . . . 55

Table

XVI VARIATION OF TRACE ELEMENT CONCENTRATIONWITH RESPECT TO WATER MASS (125°W) · . . . . . . . .

v

57

XVII TRACE ELEMENT CONCENTRATION ABOVE, WITHIN,AND BELOW THE HALOCLINE • • • • • • • • • 59

XVIII

XIX

RESULTS OF FRESH WATER ANALYSIS(CONCENTRATION ~g/l) • • • • • •

COMPARISON OF ELEMENT TO IRON RATIO FORHAWAIIAN LAVAS, LAKE WAIAU, AND DOUGLASPERCHED WATER • • • • • • • • • • • • •

· . . . . . . . .

· . . . . . . . .

62

64

LIST OF ILLUSTRATIONS

Figure

vi

1

2

3

POSITIONS OF HYDROGRAPHIC STATIONS FORCOLLECTION OF SEA WATER SAMPLES • • • •

ISLAND OF HAWAII SHOWING LOCATION OF LAKE WAIAUAND DOUGLAS CINDER CONE • • • • • • • • •

LOCATION OF FRESH WATER SAMPLES FROMEASTERN UNITED STATES • • • • •

· . . . .

4

5

7

4 STANDARD CURVE FOR URANIUM INCLUDING BACKGROUND.SLOPE: 3350 COUNTS/~G/100 SEC. • • • • • • • •

5 STANDARD CURVE FOR COPPER INCLUDING BACKGROUND.SLOPE: 3410 COUNTS/~G/100 SEC. • • • • • • • •

6 STANDARD CURVE FOR NICKEL INCLUDING BACKGROUND.SLOPE: 3950 COUNTS/~G/100 SEC. • • • • • • • •

7 STANDARD CURVE FOR COBALT INCLUDING BACKGROUND.SLOPE: 3330 COUNTS/~G/100 SEC. • • • • • • • •

8 STANDARD CURVE FOR IRON INCLUDING BACKGROUND.SLOPE: 3000 COUNTS/~G/100 SEC. • • • . • • •

· · · · · 15

· · · · · 16

· · · · · 17

· · · · · 18

19

9

10

11

12

13

STANDARD CURVE FOR MANGANESE INCLUDING BACKGROUND.SLOPE: 2120 COUNTS/~G/100 SEC. • • • • • • ••

CONCENTRATION OF U~\NIUM, COPPER, AND NICKEL INRELATION TO DEPTH FOR COASTAL (---) ANDMID OCEAN (-) WATERS •••• • • • • • • • •

CONCENTRATION OF COBALT, IRON, AND MANGANESE INRELATION TO DEPTH FOR COASTAL (---) ANDMID OCEAN ( ) WATERS • • • • • • • • • • • • .

LOCATION AND DEPTH OF SAMPLES COLLECTED ALONG THEWEST COAST OF THE UNITED STATES (125°W).ISOHALINES ARE ALSO SHOWN WITH SALINITY IN 0/00 •

POSITION AND DEPTH OF SEA WATER SAMPLES COMPAREDTO MAJOR WATER MASSES (160 0 W). SALINITY IN °ioo

20

52

53

54

56

INTRODUCTION

The determination of trace elements in sea water is necessary to

study the geochemical properties and geographical distribution of these

elements. A method which permits the determination of a nU1TIDer of

elements in one sample of sea water without chemical separation and the

elimination of storage of sea water samples for shore analysis are most

desirous. When more than one element is determined a study Clf

relationships between elements and a comparison of the reactivities of

the elements in sea water are possible. If a single sample is used for

the analysis of all elements, then observed differences are due to

variations in reactivities not to sampling differences. Chendcal

separation of the elements can lead to contamination and loss problems,

as can storage of sea water samples.

Schutz and Turekian (29) have carried out geographical distribution

studies using neutron activation analysis but, because of interference

due to the activation of sodium chloride, extensive chemical

separations were necessary after activation. Freeze-drying was used as

the method of preconcentration. Only three elements, cobalt, nickel,

and silver, of the 18 elements analyzed are discussed in detail, because

of contamination and chemical problems.

Atomic absorption spectrometry has been used for the analysis of

sea water (3,15,19), but is not really a multi-element method. Sensitive

analysis for more than one element must be done using a separate source

lamp for each element and the appropriate lamp must be installed each

time a different element is analyzed. Problems also arise from flame

chemistry, such ass intereferences (both spectral and chemical) and

2

volatilization. Some elements, for example uranium, form refractory

oxides in the flame and thus are not volatilized, leading to high

detection limits. When atomic absorption is applied to sea water a

preconcentration-separation step is necessary to remove the trace

elements from the sea water matrix. Preconcentration is necessary

because many of the elements of geochemical interest are at or below the

detection li~its of the method. If sea water is aspirated directly into

the burner, the high solids content of the flame causes scattering of

the light source beam and leads to spurious results.

X-ray fluorescence spectroscopy is useful in multi-element analysis

because the relative simplicity of x-ray spectra yields few spectral

interferences, thus many elements can be determined without chemical

separations. Enhancement and absorption effects can be eliminated by

using a thin layer technique (10,20,23) and spectral interferences can

be predicted and easily corrected. The thin layer technique is

particularly adaptable to trace analysis. Since x-ray spectra do not

depend on the chemical state, the state need not be known in order to

perform an x-ray analysis.

X-ray fluorescence analysis has a lower detection limit of about

1 ppm, but the trace elements in sea water are in the ppb range and

therefore preconcentration by a factor of 1000 is necessary. Since sea

water contains about 3.5% dissolved solids, separation of the trace

constituents from the major constituents is also necessary.

Preconcentration-separation.tedhniques have been proposed by Natelson,

et ale (20) and Morris (18) for x-ray fluorescence analysis of sea

water. Both techniques are discussed in the Experimental section of the

3

thesis. X-ray fluorescence analysis requires only one excitation source

for the analysis of a large number of elements.

A preconcentration-separation method in conjunction with x-ray

fluorescence has been developed in this research and has been used to

make a distribution study of certain trace elements for the north

eastern Pacific Ocean. Samples were collected at various depths from

the major water masses along the 160 0 west meridian (Figure 1), as

dete~~ned by the Johns Hopkins Oceanographic Studies No.2 (28). They

were ~xamined to ascertain whether the trace element distribution can be

used as an indicator of the various water masses. Similar work has been

reported by Schutz and Turekian (29) for the world oceans for the

elements silver, nickel and cobalt.

Samples were also taken along the north western coast of the United

States (Figure 1). These samples permitted study of coastal effects on

trace element concentrations. As an example, a comparison of literature

values for uranium concentrations in open ocean (17) and coastal (1)

waters showed a marked decrease for coastal water.

The method was also applied to fresh water analysis and a number of

fresh water studies were carried out. The fresh water samples were

obtained from Lake Waiau (35), a small permanent lake at 3970 meters

elevation on the inactive volcano, Mauna Kea, on the island of Hawaii

(Figure 2). There is considerable interest in waters of this lake, as

it supports a large seasonal algal population (35) and its only source

of water is rain and snow. This study was focused on a comparison of

the trace element concentration of the water, concerning which there are

no data available, and the lava rock surrounding the lake. Weathering

o 10

CD 14

0 22

I I

FIGURE 1. POSITIONS OF HYDROGP~PHIC STATIONSFOR COLLECTION OF SEA WATER SM1PLES

4

5

FIGURE 2. ISLAJ'.m OF H...\"\.JAII SEOL-lING LOCATIONOF LAKE \vAI.AU (a) AND DOUGLAS CINDER CONE (b)

6

of the lava rock is considered to be a possible source for these elements.

Another sample studied was perched water obtained from the Douglas

cinder cone on Mauna Kea at about the same elevation as Lake Waiae

(Figure 2). Perched water is water held in an elevated position, in

this case, the depression at the top of the cinder cone. This "lake"

does not have an open surface. The water level is about 0.5 meters below

the top of the coarse material which makes up the cinder cone. The

reason for the water not rapidly draining away through the material of

the cone is not known. This sample was analyzed for comparison with

Waiau. Both bodies of water have the same environment and source of

water, but Waiau has a large seasonal algal crop and Douglas has very

little, because sufficient light does not penetrate to the water level.

Another group of samples originated from various sources in

western Pennsylvania and one sample from Lake Champlain (Figure 3). The

samples from Pennsylvania were drawn from the Shenango River Reservoir,

Conneaut Lake, Mahoning River, and a mountain spring about 20-30 miles

east of Knox, Pennsylvania. The Lake Champlain sample was obtained

about 2 miles north of Saint Albans Bay, Vermont. These samples were

analyzed to obtain the dissolved and particulate trace element content

and to compare these with the content of Waiau and Douglas.

UNITED STATES ,/

<(:

ATLAl[i'IC

/IcJ~)! ~~_

FIGmm 3. LOCATION OF FRESH HATER S.'!;"'1PLESFROM EASTEro~ UNITED STATES

a. La:<:e Champlainb. springc. Conneaut Laked. Shenango Reservoire. Mahoning River

7

EXPERIMENTAL

Preliminary Studies

Originally the Natelson Technique (20) or some modification was to

be developed into a useful method of analysis. This, however, did not

prove to be possible, although the technique did have some usable

features, especially the employment of a thin deposit on a filter paper

disk. A similar procedure has been used by other workers (10,16,23,27).

In the Nate1son technique, five milliliters of sea water were

evaporated to dryness and the residue mixed with one normal hydrochloric

aCid, glacial acetic acid, and acetic anhydride. The solution and

precipitate were mixed well, allowed to stand over night, and

centrifuged. The supernatant was evaporated to dryness and the residue

taken up in a methanol-hydrochloric acid mixture. The resulting solution

was evaporated as a spot on 37 rom filter paper using a ring over (20).

The glacial acetic acid-acetic anhydride reagent was used to

precipitate the sodium chloride from the sea ,vater and thus prevent

large sodium chloride deposits in the spotting step. Such deposits

interfered with the x-ray fluorescen~c ~lalysis by causing intense and

inconsistent scattering of the primary x-rays and, therefore aggravated

the background problem. It also reduced the sensitivity of the x-ray

method due to the thickness of the salt deposit on the disk. The

combination of chemicals used proved to be successful for the removal

of sodium chloride, but such salts as calcium chloride and magnesium

chloride are not removed (5,6). Sufficient quantities of these

materials were carried through to give hygroscopic deposits about one or

two millimeters thick which proved to be impossible to control with

9

respect to thickness, size, and shape.

An additional problem was the time involved in an analysis.

Although a number of samples were handled simultaneously, the total

process took about three days. Furthermore, the small volume of sea

water used created difficulties. Since the minimum detection limits

(Table I) of the x-ray method indicate that at least 100 milliliters of

sea water must be used to analyze with precision the elements involved,

the method could not be applied usefully to these elements. It was not

practical to increase the volume of the sea water used, since a 100 m1

sample would require the addition of 130 m1 of acetic anhydride and

would extend the evaporation time to days instead of hours. The method

was discarded because of these difficulties, but the use of the ring

oven was retained. Spots prepared with the help of the ring oven by

evaporating known volumes of methano1ic standard solutions, were very

useful in showing that thin deposits were of considerable value in

x-ray analysis.

It was decided because of the value of such deposits to employ a

method used in atomic absorption spectrometry in conjunction with x-ray

fluorescence. The solvent extraction of trace e1em8nts using ammonium

pyrro1idine dithiocarbamate (APDC) as the comp1exing agent and

methy1isobuty1ketone (MIBK) as the extracting agent has been used

successfully in atomic absorption work (3,15,19). The MIBK extract was

to be evaporated as a spot on the filter paper and then analyzed in the

x-ray instrument, but a problem was encountered in the deposition step.

The extract chemically attacked the filter paper making it very brittle,

to the extent that it fell apart when handled. Such fragility precluded

TABLE 1. COMPARISON OF DETECTION LIMITS FOR X-RAYFLUORESCENCE AND ATOMIC ABSORPTION SPECTROMETRY

AND NEUTRON ACTIVATION ANALYSIS

DETECTION LIMITS IN MICROGRAMSX-Raya Atomicb Neutronc

Element Fluorescence Absorption Activation

Uranium 0.014 180 0.002

Copper 0.026 0.030 0.005

Nickel 0.005 0.030 0.028

Cobalt 0.002 0.030 0.00005

Iron 0.005 0.030 0.28

Manganese 0.006 0.012 0.0005

aBased on experimental data for background andslope measurements, 1000 second counting time, and asignal one cr. greater than background.

bBased on detection limits given by Perkin ElmerCorp. for the 303 Atomic Absorption Spectrophotometerand the necessity of using 6 m1 of solution to analyzefor all 6 elements in the same solution.

cSee appendix III.

10

11

its use in the x-ray instrument. To rectify the problem removal of all

organics by evaporating the MIBK extract to dryness and oxidizing the

residue with nitric acid was attempted. The final residue could be

taken up in deionized water and spotted on filter paper. A publication

by Morris (18) appeared at this time which gave a similar solution to

the problem.

The published method although similar to the method just discussed

had some drawbacks. These involved need for pH adj ustment with the

attendant risk of contamination, the use of large amounts of APDC, the

requirement of special extraction equipment, and several evaporation

steps with risk of loss of metals by adsorption on the container walls.

Finally the method used by Morris (18) for presenting the sample to the

x-rays involved mixing a final residue with cellulose powder and

compression of the mixture into a 2.54 cm diameter pellet. Only about

one fourth to one third of the area of the pellet was excited by the

x-rays and penetration of the secondary x-rays was about 0.2 rom

(Appendix II), consequently, the method suffers from reduced sensitivity

since a portion of the sample is not excited.

·At this point an entirely different approach was attempted. Some

work by Carritt (4) apparently provided a method based on the use of

dithizone impregnated cellulose acetate columns for the removal of

certain trace elements from sea water. A complete description of the

column method developed is presented in Appendix I.

Although the method worked well with the standards, it could not

be applied satisfactorily to the analysis of sea water, since it did not

cover a wide enough concentration range. It worked well for zinc and

12

copper but poorly for iron and manganese and little, if at all, for

nickel, cobalt and chromium. It was then concluded, by calculation of

critical depth for secondary x-rays (Appendix II), that the method could

not be made sensitive enough for the determination of nickel, cobalt,

and chromium. Use of larger volumes of sea water would not help because

the added amounts of copper and zinc would necessitate larger columns.

For this reason there would be no gain in the metal to cellulose acetate

ratio, which was necessary to increase the sensitivity.

Following a study of the results of the calculations concerning

this problem and their significance when applied to pellets, it was

decided that thin deposits on the order of 0.1 rom were essential. The

sole method found to accomplish this was by spotting on filter paper

using the ring oven. This requirement plus the need to develop a method

sensitive enough to use in the analysis of the 120 to 240 m1 samples

available, led to the procedure finally adopted.

Final Analytical Method

The final method adopted some of the best features of the previous

work. Solvent extraction at the natural pH of sea water using a wide

spectrum extracting agent and a readily volatilized solvent were

required. The 8-hydroxyquinoline-Chloroform system fits these needs

well.

A. Chemicals and Apparatus

The chemicals used in the final method were redistilled reagent

grade chloroform, methanol, and 8-hydroxyquinoline (8-HQ). Analytical

13

reagent grade salts were used to make up standards for the elements

analyzed (Table II). Doubly distilled deionized water was used

throughout the entire work. Purified hydrochloric acid and aqueous

ammonia used for pH adjustment were made up as described in the

procedure.

The major pieces of equipment used were a kinetic clamp pump from

Sigmamotor, Inc., a ring oven fron Scientific Industries, Inc., and a

vacuum x-ray spectrometer equipped with a FA-60 tungsten target x-ray

tube and a lithium fluoride analyzing crystal from Norelco (Phillips

Electronics Instr.). Miscellaneous glassware and an 800 watt variable

hotplate were also used.

B. Preparation of Standards and Standard Curves

Standards were prepared by dissolving known quantities of reagent

grade salts of the metals in doubly distilled deionized water. A

concentration of one gram of metal per liter of standard was prepared

(Table II). Two liters of each standard were made.

The secondary standard was prepared by diluting a mixture of

appropriate volumes of primary aqueous standards to one liter using

reagent grade absolute methanol. Methanol was used for reasons

explained in the operation of the ring oven. This standard was stable

as long as it was protected from evaporation. The concentrations of

each element in the secondary standard were chosen to be: 2.00 pg/ml,

uranium; 10.0 Vg/ml, copper; 2.00 Vg/ml, nickel; 1.00 Vg/ml, cobalt;

5.00 Vg/ml, iron; 5.00 Vg/ml, m~~ganese.

Standard curves (Figures 4-9) were prepared by direct evaporation

of known quantities of the secondary standard solution on filter papers.

TABLE II. COMPOUNDS AND AMOUNTS USED INPREPARATION OF PRIMARY STANDARDS

GRAMSCOMPOUND per 2 liters

U02 (C2H302)2· 2H20 3.56

CuS04·SH20 7.68

NiS04·6H20 8.96

Co(N03)2·6H20 9.88

MnS04·H20 6.16

Fe (NH4) 2 (S04)2·6H20 14.04

14

500

'CJ 400 ,,.~oCJQ)CIl

HQ)Po 300 • ..0=

~:ICc.

----.~=! : ..c:~-,.. -"".£....-

200 ·f:>

CIl0/-1

§o

u100 ,~

~_J=_.=~....J~• ~.~<~L=_~~ ,

0.4 0.8 1.2 1.6 2.0

Micrograms of Uranium

FIGURE ll. STANDARD X-RAY FLUORESCENCE CURVE FOR URANIUH INCLUDING BACKGROUND.SLOPE 3350 COUNTS/~G/I00 SEC.

I-'VI

HQ)

P< 1200 la

'IJ 1600,....~otJQ)C/)

2000

....fl.- _~:-:.~r

800-'-~~-~" ---------~-••- ~.-l~-,~~j-""'~

C/).w§ou

400 I ...

_. v_I__-~ ..._.~ L.~_.~--L..

I 2.0 4.0 6.0

Micrograms of Copper

I ~

8.0 10.0

FJGURI.~ 5. STANDARD X-RAY FLUORESCENCE CURVE FOR COPPER INCLUDING BACKGROUND.SLOPE 3410 COUNTS/~G/100 SEC.

f-'

'"

150

120

'0l=l8 90<IJ(J)

).1<llp..

2l 60§o

u

7~

=!:5Pc u­30

..._ ...~__~___ ,__ _\ I l J

f 0.4 0.8 1.2 1.6 2.0

Hicrograms of Nickel

FIGURE 6. STANDARD X-RAY FLUORESCENCE CURVE FOR NICKEL INCLUDING BACKGROUND.SLOPE 3950 COUNTS/~G/100 SEC.

l-'

'"

50

40

r-elP8 . 30''''Q)

Ul

HQ)p,

Ul 20·­.j..J

§ou

10,-

=C'C:

:in6~

I 0.2

, L-~,_.. , __~_.-..:J

0.4 0.6 0.8 1.0

Hicrograms of Cobalt

FIGURE 7, STANDARD X-RAY FLUORESCENCE CURVE FOR COBALT INCLUDING BACKGROUND,SLOPE 3330 COUNTS/~G/I00 SEC.

I-'co

40 1- =-'..)=--<.,-c.. ,..;)_

J~-~, I I , ! II 1.0 2.0 3.0 4.0 5.0

200

160

rop

120 .-0tJQ)til

l--lQ)P<

til 80 ..-.jJ'p~0u

Hicrograms of Iron

FIGURE 8. STANDAPJ) X-l~Y FLUOP~SCENCE CURVE FOR IRON INCLUOING BACKGROUND.SLOPE 3000 COUNTS/~G/100 SEC.

I-'\0

15Q-

"0P8 9Q)l1J

HQ)p..

fl 60'-

Sou

30(..- T:2rC

/--J-:.c

-[ I J

LO 2.0

,__",-I_, ~~.L__

3.0 4.0----.J

5.0

Micrograms of Nanganese

FIGURE 9. STANDARD X-r-A.Y FLUORESCENCE CURVE FOR NANGANESE INCLUDING BACKGROUND.SLOPE 2120 COm~TS/~G/100 SEC.

No

21

By pumping directly from a 5 m1 buret, it was possible to measure very

easily the volume deposited on each filter paper. The buret was also

used to measure volumes of solution used in spiking both sea water and

fresh water for the determination of extraction efficiency.

Standards were checked by atomic absorption spectrometry using

independent standards prepared by dissolving known weights of the free

me ta1s • The uranium standard was checked by gravimetric means. A

known volume of the standard was treated with 8-HQ and the precipitated

uranium 8-hydroxyquinolate was dried and weighed. In all cases the

standards checked within experimental error (5%).

C. Procedure

If the sample to be analyzed was sea water, it was extracted

directly without pretreatment. ~e ~H' of a 1imno1ogica1 sample was

adjusted to between 7 and 9. If the pH exceeded 9, magnesium and

aluminum 8-hydroxyquino1ates were also formed and extracted (30), causing

difficulty in the spotting step by the formation of thick deposits. The

adj ustments of the pH were made with isopiestic hydrochloric acid and

aqueous ammonia, prepared using doubly distilled deionized water, to

avoid contamination.

(1) A 100 to 500 milliliter sample was placed in a separatory

funnel of appropriate size equipped with a Teflon stopcock and the pH

adjusted, if necessary, as described.

(2) One milliliter of 10% 8-HQ in methanol (w/v) was added to the

sample. This was mixed and allowed to stand for 5 minutes. The

solution was yellow at this point.

22

(3) Eight milliliters of chloroform were added and the mixture

shaken vigorously until there was a marked decrease in the yellow color

of the aqueous phase~ a change which required 10 to 15 seconds. After

the chloroform layer had separated, it was drained into a seven dram

glass vial. An additional 6 m1 of chloroform was added to the sample,

shaken, and drained into the vial. After the second extraction the

aqueous phase was colorless or milky white.

(4) Steps (2) and (3) were repeated and all extracts collected in

the glass vial.

(5) The combined extract was evaporated to dryness on a 70-80°C

hot plate by directing a gentle stream of air onto the surface of the

extract. This step required less time than the preparation and

extraction of the next sample. The total time for all work to this

point was on the order of 20-25 minutes. Three samples treated

together require an additional 10 minutes.

(6) The dried sample was sealed, before cooling~ in the glass vial

with a plastic cap which may be stored at least a month without change.

(7) The sample was dissolved in a minimum volume of chloroform

(1-2 ml). At this point, an internal standard of some metal not

extracted could be added as a methanolic solution, if desired. The

internal standard employed was one milliliter of a 1.00 ~g/m1

methanolic solution of Chromium (III) nitrate. The addition was found

subsequently, to be unnecessary and this step could be omitted, although

it was carried out for all samples.

(8) The sample solution was pumped by a kinetic clamp pump from

the glass vial througll Teflon tubing to a ring oven where it was

23

evaporated as a spot on 37 mIll #541 or #546 Whatman filter paper. The

glass vial was rinsed at least twice with chloroform. The pumping rate

was about 5-7 ml/hr and the ring oven was operated at a temperature of

160°C, at which temperature all unreacted 8-HQ was evaporated. At

temperatures as low as 80°C, 8-HQ evaporated readily but 160°C gave the

best overall results for spotting.

(9) The spotted filter disks were placed in 2 dram glass vials,

sealed with plastic caps. They may be stored indefinitely without

change if desired.

(10) The disks of the prescribed dimensions fit the sample holders

of the Norelco x-ray spectrometer. The following conditions for the

x-ray equipment were used for analysis: pulse height analyzer, window­

25 volts, width-5 volts; tungsten target x-ray tube, 45 kilovolts and

45 milliamps, with a 0.002 inch titanium filter; scintillation counter,

1000 volts; and gas flow proportional counter, 1590 volts, with a P-10

gas flow rate of one standard cubic foot per hour. The spectrometer

was evacuated to 200 microns or better for all measurements.

The scintillation counter was used to measure the Loc radiation

intensity of uranium. The gas flow proportional counter was used for

all other elements, because the scintillation counter did not give

higher count rates. All samples were rotated at four revolutions per

minute for uniform exposure to the primary beam. The samples were

counted twice for 100 seconds and the average used. This time period

was found to give satisfactory results on the basis of counting

statistics.

24

D. Discussion of the Procedure

Complete extraction (95-100% of the elements concerned was achieved

for both fresh and sea water (Tables IV and III). There is a significant

relationship between sample volume~ e1ement~ and 8-HQ concentration

(Table V). In the case of manganese~ it was necessary to increase the

8-HQ concentration for sample volumes larger than 150 milliliters.

Although two additions of 8-HQ together with four chloroform

extractions are recommended by the procedure~ Table VI shows that 95% or

more recovery of the metals was realized in the first extraction with

one exception. Only 60-70% of the manganese was removed by the first

extraction with the remainder removed in succeeding extractions~ thus

necessitating multiple extractions.

The five minute time delay adopted in the extraction procedure was

shown to be necessary according to experiments summarized in Table VII.

Manganese~ again~ gave unexpected results for which there is no known

explanation.

In the primary evaporation step~ the vial was not permitted to

remain on the hot plate after the Chloroform had evaporated. If this

precaution was not taken most of the excess 8-HQ would also evaporate.

If this occurred~ it was doubtful whether all of the 8-hydroxyquino1ates

could be redissolved. These could be adsorbed on the glass in such a

Ban~er as to make redissolVing difficult. When they were suspended in

excess 8-HQ~ redissolving posed no difficulty. During the evaporation~

8-HQ was deposited as rings around the vial as the liquid level dropped.

After complete evaporation of the solvent~ the sides of the vial were

rinsed with a small amount of chloroform which, in turn~ was evaporated.

TABLE III. EXTRACTION EFFICIENCY OF THE 8-HQ-CHC13 SYSTEMFOR SPIKED SEA WATER SAMPLES

Element

llg added

llg recovered*

percent

Uranium

2.0

2.0

100

Copper

10

9.7

97

Nickel

2.0

2.0

100

Cobalt

l.0

l.0

100

Iron

5.0

5.0

100

Manganese

5.0

4.8

96

*Amount due to sea water has been subtracted.

NVI

TABLE IV. EXTRACTION EFFICIENCY OF THE 8-HQ-CHC13 SYSTEMFOR SPIKED DEIONIZED WATER SAMPLES

Element

~g added

~g recClvered

percent

Uranium

2.0

1.9

95

Copper

10

9.6

96

Nickel

2.0

2.0

100

Cobalt

1.0

1.0

100

Iron

5.0

4.9

98

Manganese

5.0

4.9

98

N0\

TABLE V. RELATIONSHIP OF S~IPLE VOLUME TO PERCENTEXTRACTION EFFICIENCY OF THE 8-HQ-CHC13 SYSTEM

Element Uranium Copper Nickel Cobalt Iron Manganese

Volume 500 97 96 100 100 96 45

in 250 100 95 101 100 98 80

Mi1lili ters 100 99 99 100 101 100 99

!'.'-....I

TABLE VI. RELATIONSHIP BETWEEN SAMPLE VOLUME AND PERCENT EXTRACTED IN EACH STEP(8-HQ IS ADDED IN THE FIRST AND THIRD STEPS)

Element .Urc¢ium Copper Nickel Cobalt Iron Manganese

Volume Step

500 ml 1 95 96 98 95 95 302 0 3 2 3 3 43 3 0 1 1 2 184 1 1 0 1 0 3

250 m1 1 96 96 97 97 96 502 0 4 3 3 3 43 2 0 0 1 1 204 1 1 0 0 0 5

100 ml 1 98 96 97 97 96 702 0 2 2 2 3 43 0 2 1 1 0 204 1 0 0 1 0 3

N00

TABLE VII. EFFECT OF TIME DELAY AFTER ADDITION OF 8-HQ ONEXTRACTION EFFICIENCY (PERCENT)

Element Uranium Copper Nickel Cobalt Iron Manganese

Time

in

Minutes

a

1

5

81

100

99

96

100

98

47

69

100

46

60

101

77

92

98

88

60

100

N\0

30

In redissolving, the smallest volume of chloroform possible was

used. One milliliter was usually sufficient. The smaller the volume

used, the shorter the time required for spotting. The same situation

also applied to the rinses.

The samples obtained from the primary evaporation step were stored

in the dark or in subdued light. Although the 8-hydro:h-yquinolates were

light stable, the 8-HQ in solution was somewhat unstable (30). The

stock solution was kept in a glass bottle, completely wrapped to exclude

light. All primary evaporation samples were kept in light tight boxes

of the type used to package light sensitive chart paper.

The kinetic clamp pump was very useful in the deposition step of

the method. Many schemes were tried to control the addition rate of

the samr"le solution, during this step. The problem was resolved

satisfactorily, through the use of the pump which allowed complete and

facile control of the rate. Such control was necessary for the

production of constant spot sizes using the ring oven.

The pump worked by repeatedly squeezing slugs of liquid through

resilient tubing. The rate of pumping was controlled by varying the

voltage to the direct current motor, which drove the pump.

Operation of the pump was very simple and the only difficulty

encountered was the selection of the type of tubing to be used in

pumping chloroform solutions. Gum rubber, silicone rubber,

polyvinylchloride, polyethylene, and Teflon tubing were tried. The

first three dissolved in chloroform to some extent. Polyethylene and

Teflon tubing worked well but Teflon was finally Chosen since it could

be rinsed more cleanly and more easily than polyethylene. When the

31

Teflon tubing was first tried in the pump~ it was crushed flat with

resultant loss of pumping ability following a few revolutions of the

pump. Since polyethylene had sufficient resiliency, a combination of

polyethylene and Teflon tubing was used. A short, 3 inch, section of

polyethylene tubing, 3/16 inch O.D. by 1/8 inch I.D., was slipped over a

36 inch piece of Teflon tubing, 3/32 inch O.D. by 3/64 inch I.D. The

polyethylene tubing was heated and stretched lengthwise about 100%. The

stretching caused it to shrink snugly to the Teflon, imparting the

necessary resiliency to the Teflon tubing. The combination of

polyethylene and Teflon tubing so constructed was used for pumping about

400 samples and still worked efficiently.

The ring oven was essential, since, with its use, reproducible spots

were formed. The construction of the ring oven has been discussed by

others (20). It consisted of a set of thermostatically heated rings

between which the filter paper was placed. As the solution was deposited

in the center of the filter paper and rings, it spread toward the hot

rings and evaporated before reaching them. This resulted in the

dissolved material being deposited in a spot about 1 cm in diameter in

the center of the filter paper.

The only variables in the operation of the ring oven were

temperature of the rings~ flow rate of the solution to the oven and flow

rate of the air through the central tube. The following set of

conditions gave optimum results: a temperature of 160°C, a solution

flow rate of 5-7 m1/hr, and an air flow rate which just caused the

filter paper to flutter but not float without the upper ring in place.

If the spot appeared to be too large or small, the solution flow rate

32

was adjusted with the pump. The rinses were deposited at about double

the rate of the initial solution.

X-ray fluorescence, which was used to complete the analytical

method, is usually not the method of choice for trace analysis. In

x-ray fluorescence the x-rays from the sample are excited by x-rays of a

shorter wavelength from another source. The intensity of such x-rays

is about 0.001% that obtained in electron excitation and as a result,

x-ray fluore~cence is usually not useful below the parts per million

(p.p.m.) range. Since the metals analyzed were in the parts per billion

(p.p.b.) range, it was necessary to concentrate the metals at least a

factor of a thousand to apply x-r~y fluorescence. The extraction method

already discussed more than met this requirement with a concentration

factor of about fifty thousand. This factor was based on a final

concentration in the filter paper of 0.5 parts per thousand (p.p.t.) with

the initial concentration in solution of 1 p.p.b.

X-rays arise when an inner shell electron is ejected from an atom

by a high energy electron or photon. The K~ series which was used for

all elements analyzed except uranium arises when an electron is ejected

from the K shell and this hole is filled by the transfer of an electron

from the L shell to the K shell. The energy change in the transfer is

released as an x-ray photon with energy equal to the difference between

the initial and final energy states of the transferred electron. The L

series arises from the ejection of an electron from the L shell and

subsequent filling of this hole by an electron from a higher shell. The

L~ line was employed in the analysis of uranium because the x-ray tube

used would not produce x-rays of sufficient energy to excite the ~

33

radiation of this element. The La: line is also the most intense line of

the L series.

The siQplicity of x-ray spectra provides little possibility for

spectral interference. Examination of the literature (18,20) discloses

that the only possible interference was that of the chromium Ke line

with the manganese Ka: line. Since the chromium Ke line could not be

resolved from the manganese Ka; line, it added to the manganese peak.

Chromium was not extracted under the conditions described and when added

as an internal standard, it was present in a constant amotmt,

consequent:y, its Ke radiation is constant and could be included in the

manganese background. The Ke line of an element is less intense than

the Ka: line and therefore the chromium Ke 'twuld only add. an average of

2 counts per second to the manganese backgrotmd, which is insignificant.

The maj or source of trouble in x-ray fluorescence analysis in any

analysis is the background. An increase in the background causes an

increase in ~he absolute uncertainty of the background measurement and

thus decreasing the sensitivity. In the case of most x-ray tubes the

target metal is not pure. Because of these impurities the primary

x-rays include not only lines characteristic of the target metal but

also those of the impurities. The tungsten target tube used showed such

lines for copper, nickel, manganese, and iron. A titanium filter in

the primary beam has been found very useful in decreasing such radiation

(20) • For this purpose, two layers of 0.001 inch titanium foil were

taped directly over the exit window of the x-ray tube. Both thicker~

0.005 inch, and thinner, 0.001 inch, filters have been tried by other

workers (1&,20), but the above thickness was found most effective.

34

A major advantage of the final method is the possibility of

extracting samples on board ship, as they are collected. This

eliminates or greatly reduces such problems as adsorption and desorption

of the species of interest on the container walls, biological activity,

and speciation changes, which arise when sea water is stored for shore

analysis. The method requires only simple equipment, few reagents, and

relatively little time is required to accomplish the extraction and the

primary evaporation. Such conditions are very important in ship board

work. Since the dried material obtained from the primary evaporation is

stable, sea water samples can be extracted and the dried material stored

at sea with final analysis performed ashore.

Another advantage inherent in the method is the low probability of

contamination, because few reagents are involved and no pH adjustment

or buffering are necessary.

The extraction method also does not limit the final analytical

method to x-ray fluorescence. Both atomic absorption spectroscopy and

neutron activation C~l be used, although the former is not as sensitive

on an absolute quantity basis as x-ray fluorescence (Table I).

When x-ray fluorescenc~ is used for the final analysis, other

advantages become evident. The excess 8-HQ is evaporated during the

spotting step along with the solvent, resulting in a thin deposit. The

thickness of these deposits, therefore, depends on the amount of metal

8-hydroxyquinolates extracted from the water sample and not on the

amount of 8-HQ used in the extraction.

Standards are prepared by spotting known volumes of standard

methanolic solutions of the elements of interest on filter papers.

35

Methano1ic solutions are used because they evaporate readily in the ring

oven where aqueous solutions evaporate only slowly due to the high heat

of vaporization of water. Filter papers spotted this way can be used

for standards because x-ray spectra do not depend on the chemical state

of the elements. The reagents used in the analysis do not add to the

background, consequently, the background is the same for both extracted

and direct deposition standards.

Finally, samples analyzed by x-ray fluorescence are not destroyed

nor become radioactive, and can be analyzed and stored for future

reference.

There are, of course, some disadvantages, which are not major. A

troublesome problem is the fact that the chemical speciation of the

elen~nts in sea water is in doubt. This leads to the basic question of

whether all of a certain element present in the sample is extracted or

extractable. This problem is taken up in the discussion of results.

A final difficulty, which can be avoided by careful choice of

sample volume, arises if excessively large amounts (hundreds to

thousands of micrograms) of 8-hydroxyquino1ates are deposited during the

spotting step. In this event, the layer can no longer be considered

thin and the releation between the amount of metal present and the x-ray

intensity will not be linear.

RESULTS AND DISCUSSION

The method as finally developed was capable of analyzing sea water

and fresh waterfor uranium, copper, nickel, cobalt, iron, and manganese.

Table I gives the minimum detection limits for x-ray analysis of

the elements involved. These limits are based on a 1000 second counting

time and a signal at least one (J greater than background. The background

and slope measurements necessary for the determination of the detection

limits were obtained from the standard curves. One thousand seconds was

used as a maximum counting time because it is consistent with both short

term and long term drift of the instrumentation (12).

The precision of this method depends on the element and the amount

of the element analyzed. The precision was determined by analyzing a

series of samples prepared by direct evaporation of methano1ic standards,

extracting spiked sea water, and extracting spiked deionized water. The

first two consisted of five groups of five replicates with a

concentration range for each element the same as that shavln in the stand­

ard curves (Figures 4-9). The final series consisted of three groups of

five replicates over the same concentration range. The precisions

calculated for each series were the same. within experimental error.

The data are summarized in Table VIII. The first two rows of the

table give the precisions at the maximum and minimum levels of the

analysis described above. The other two rows give the precisions at the

average levels of the sea water and fresh water analysis.

In the actual determinations of the 120 ml and 240 m1 sea water

samples, a precision of 10% was obtained for copper, nickel, iron, and

manganese, out a precision of 20% and 30% was obtained for uranium and

TABLE VIII. PRECISION IN ~g AND % FOR THE EXTRACTION METHOD BASED ON EVAPORATED ANDEXTRACTED STANDARDS FOR MAXIMUM AND MINIMUM AMOUNTS ANALYZED.

AVERAGE PRECISION OF THE ACTUAL SEA WATER AND FRESH WATER ANALYSIS.

Elements Uranium Copper Nickel Cobalt Iron Manganese

Maximum 2.0±0.1 10.0±0.5 2.0±0 .1 l.0±0.05 5.0±0.25 5.0±0.255% 5% 5% 5% 5% 5%

Minimum 0.02±0.02 0.10±0.OB 0.02±0.01 0.01±0.01 0.05±0.04 0.05±0.05100% 80% 50% 100% 80% 100%

Average Precision 0.38±0.08 5.4±0.5 0.30±0.03 0.04±0.01 0.95±0.1 0.54±0.06for Sea Water 20% 10% 10% 30% 10% 10%Analysis

Average Precision 0.59±0.08 2.1±0.2 0.66±0.06 0.06±0.01 3.5±0.30 4.8±0.30for Fresh Water 15% 10% 10% 20% 9% 6%Analysis

VJ-...J

38

cobalt respectively. The reasons for the relatively poor precision of

uranium and cobalt are different. A 1-2% variation in the uranium

background can cause a 10-20% variation in the analysis result.

Variations in cobalt analysis are due to the very small amount of cobalt

analyzed (0.04-0.08 ~g). Consequently the slightest variation or

contamination will have a large effect at this level. Data are given

only to two significant figures because of the level of the precision.

Initial data were taken to four significant figures with all

calculations carried out to three.

Accuracy wC!s not known because the accuracy of a determination can

be measured only if the true value is known and, in the case of natural

water analysis, the true value is not known. Often accuracy is checked

by analyzing spiked samples. While such a check certainly applies to

the spike it contributes little about what is actually recovered from

the real system. The speciation of the spike is known but speciation in

the real system is not, especially, in the case of sea water. The

speciation of the spikes was chosen to match those given by Goldberg for

sea water (8). A check for nonextractable higher oxidation states of

analyzed elements was made by the addition of hydroxylamine hydrochloride

to sea water to provide a reducing environment. Such an environment

insured that the elements nickel, cobalt, and manganese were in the +2

oxidation state. No increase in the recovery of the metals from sea

water was noted and, thus, higher oxidation states are apparently not a

problem in the extraction of these metals.

Table IX shows the average sea water values for this analysis and

the values obtained by other workers. In the case of uranium, an

TABLE IX. COMPARISON OF DATA FROM SEA WATER ANALYSES

PRESENT WORK PREVIOUS WORKELEMENT Concentration Concentration

Location }lg/l .Location llg/l Reference

Uranium North Central 3.3 Northwest Pacific 3.3 (17)Pacific (NCP) NCUS 1.9 ( 1)

Northwest Coast of 1.7 Oceanic Average (OA) 3 ( 8)United States (NCUS) OA 3.3 (11)

Copper NCP 35 Southeast Pacific 36 (34)NCUS 29 OA 23 (11)

OA 3 ( 8)

Nickel NCP 3.2 OA 5.4 (29)NCUS 1.1 Long Island Sound 2.1 (29)

OA 6.6 (11)OA 2 ( 8)

Cobalt NCP 0.24 OA 0.27 (29)NCUS 0.13 Long Island Sound 0.048 (29)

OA 0.39 (11)OA 0.10 ( 8)

Iron NCP 6.1 OA 3.4 (11)NCUS 5.4 OA 10 ( 8)

Manganese NCP 16 OA 1.9 (11)NCUS 1.9 OA 2 ( 8)

W\0

40

estimate of the accuracy could be made by comparison with published

values (1,8,17). Good agreement, within 5%, for the overall averages of

uranium in both mid ocean and coastal waters was obtained. Other

elements were not as easily compared because there is little agreement

of literature values (8,29). Copper values are high compared with

Goldberg (8) but a paper by Whitnack (34) gives values in good

agreement for deep water. The high values for manganese in the mid

ocean are unique and could possibly be explained by the dissolving of

particulate manganese during the long storage of the samples prior to

analysis. Contamination is not believed to be the cause since all

samples were treated identically and the mid ocean manganese values

were the only high values.

Sea Water Data

Tables X - XII and Figure 1 give the position, depth and

concentration found for each element for all sea water samples. The

most notable information obtained from these tables is the difference

between the mid ocean samples (160 0 W) and the coastal samples (125°W).

Coastal samples have 10-50% lower concentrations, depending on the

element,. than the mid ocean samples. The diffe~ence might be

attributed to a relationship between sample volume and extraction

efficiency as the volumes also differ by about 50%. Table V shows that

this is not the case. Although there is a difference for manganese, it

can be eliminated as described earlier in the discussion of the final

method. Contamination is not the cause, for the values are lower not

higher than values found for mid ocean samples. The literature (1,17)

TABLE X. VARIATION OF TRACE ELEMENT CONCENTRATION (~g/l)

Location Station fI Uranium Copper Nickel Cobalt Iron Manganese

53 0 48.1' N 163 0 30.0' W 2 3.0 43 2.2 0.36 12 11

51 0 44.0' N 161 0 08.5' W 10 3.1 37 3.2 0.37 9.0 23

45 0 57.9' N 160 0 28.0' W 13 4.0 50 4.5 0.26 6.6 11

43 0 53.2' N 160 0 19.8' W 14 3.6 24 2.9 0.31 9.0 20

38 0 21.0' N 160 0 18.0' W 19 3.9 26 3.0 0.28 6.2 340

32 0 10.5' N 160 0 17.0' W 22 3.6 18 2.3 0.22 3.9 7.4

26 0 15.1' N 159 0 59.7' W 27 3.0 44 4.1 0.22 5.8 17

24 0 50.8' N 160 0 00.6' W 29 2.2 39 2.5 0.11 4.2 22

23 0 26.6' N 159 0 58.3' W 31 4.5 42 2.2 0.22 3.8 17

~

I-'

TABLE XI. VARIATION OF TRACE ELEMENT CONCENTRATION (~g/l)

-Location Station 11 Uranium Copper Nickel Cobalt Iron Manganese

42° 59.5' N 125° 00.8' W 163 1.7 32 1.2 0.14 5.6 2.0

44° 00.7' N 125° 00.0' W 164 1.6 34 1.2 0.11 5.6 1.2

45° 00.5' N 124° 59.5' W 165 2.0 31 1.2 0.18 5.3 1.7

46° 00.0' N 125° 00.0' W 166 1.5 23 0.99 0.11 5.3 0.49

47° 00.0' N 125° 00.0' W 167 1.8 32 0.90 0.16 5.2 3.2

48° 30.0' N 125° 00.0' W 168 1.4 24 1.0 0.16 6.1 1.3

~N

TABLE XII. RESULTS OF SEA WATER ANALYSES (CONCENTRATION ~g/l)*

Station /I Depth (m) Uranium Copper Nickel Cobalt Iron Manganese

2 sur 2.5 35 2.2 0.31 11 14

2 50 3.4 51 11 0.42 13 7.5

10 sur 2.7 21 2.0 0.27 8.1 22

10 400 3.1 62 4.9 0.27 9.1 21

10 1300 3.5 28 2.7 0.56 9.8 27

10 2500

13 sur 4.1 t.3 2.3 0.36 5.7 3.9

13 300 3.3 59 3.0 0.11 5.7 13

13 800 3.3 16 8.2 0.25 8.7 17

13 2500 5.2 81 4.4 0.32 6.2 10

ll. sur 3.8 38 3.4 0.52 7.2 50

ll. 400 3.0 30 3.0 0.25 11 7.5

14 800 4.3 12 2.7 0.28 6.9 1.7

14 2500 3.5 14 2.5 0.19 11 21.

.po

*See Fig. 1. w

TABLE XII. (Continued) RESULTS OF SEA WATER ANALYSES (CONCENTRATION ~g/l)*

Station II Depth (m) Uranium Copp~r Nickel Cobalt Iron Manganese

19 sur 2.6 25 2.9 0.36 8.2 44

19 500 2.6 17 2.6 0.25 7.4 18

19 800 4.3 10 3.2 0.13 4.8 20

19 2500 6.0 53 3.1 0.39 4.6 56

22 sur 5.5 26 3.1 0.18 4.6 5.7

22 400

22 600 2.5 6 2.2 0.25 3.5 10

22 2500 2.7 21 1.6 0.22 3.5 6.4

27 sur 2.2 16 LO 0.14 3.9 16

27 400 3.9 26 2.4 0.23 4.9 29

27 600 2.6 20 2.6 0.07 6.2 5.6

27 1900 3.5 82 7.2 0.42 9.1

27 2500 2.8 77 7.4 0.24 4.8 18

29 sur :.8 26 1.3 0.12 3.3 24

29 400 4.3 47 2.1 0.14 3.2 4.8.p-.p-

TABLE XII. (Continued) RESULTS OF SEA WATER ANALYSES (CONCENTRATION ~g/l)*

Station tI Depth (m) Uranium Copper Nickel Cobalt 'Iron Manganese

29 800 1.8 21 3.8 0.12 5.8 55

29 2500 0.8 61 2.8 0.07 3.9 4.7

31 sur 2.1 60 2.3 0.13 3.3 2.7

31 400 2.9 13 1.9 0.27 4.2 21

31 1300 5.8 16 1.8 0.22 4.0 41

31 2500 7.1 78 2.7 0.28 3.6 4.5

OVERALL AVERAGE 3.3 35 3.2 0.24 6.1 16~

163 sur 1.5 32 1.8 0.11 6.3 1.4

163 100 1.9 38 1.4 0.27 9.3 4.4

163 200

163 400 1.4 11 0.63 0.16 3.7 1.1

163 800 2.0 18 1.3 0.17 4.2 4.6

163 1000 1.4 34 0.80 0.08 3.4 0.22

163 1240 1.9 57 1.2 0.04 6.4 0.44~

164 sur 1.9 60 1.5 0.16 4.7 1.3 VI

TABLE XII. (Continued) RESULTS OF SEA WATER ANALYSES (CONCENTRATION ~g/l)*

Station 11 Depth (m) Uranium Copper. Nickel Cobalt Iron Manganese

164 100 1.6 19 1.3 0.07 5.0 2.7

164 200 2.0 31 1.3 0.05 6.2 1.2

164 300 1.4 51 1.2 0.09 5.1 0.32

164 400 L8 18 1.3 0.12 7.1 0.74

16Lf 790 1.0 18 0.80 0.14 5.7 2.0

164 940 L7 42 1.0 0.16 5.4 0.50

165 sur LO 50 0.89 0.15 3.9 2.8

165 100 1.9 24 0.64 0.15 5.2 1.9

165 200 1.4 19 0.34 0.13 4.5 0.21

165 400 1.5 16 1.5 0.10 5.0 1.0

165 700 2.3 51 2.5 0.32 8.4 13

165 940 4.0 27 1.1 0.24 4.8 2.5

166 sur 1.9 25 0.59 0.10 6.3 O. Lr5

166 100 1.3 7.7 0.77 0.13 6.0 0.91

166 200 0.8 25 0.45 0.10 4.9 0.49 ~0\

TABLE XII. (Continued) RESULTS OF SEA WATER ANALYSES (CONCENTRATION ~g/l)*

-Station It Depth (m) Uranium Copper Nickel Cobalt Iron Manganese

166 400 1.6 39 0.86 0.17 5.6 0.29

166 600 1.6 14 0.78 0.01 4.5 0.26

166 800 1.9 21 2.1 0.09 4.9 0.53

166 1000 1.4 27 1.4 0.11 4.7 <0.2

166 1240

167 sur 1.4 38 0.80 0.19 5.8 2.4

167 50

167 100

167 200 1.8 24 0.49 0.09 2.8 4.3

167 225 2.5 41 1.5 0.17 5.9 5.1

168 sur 1.1 21 0.46 ---- 4.4 1.2

168 50 1.4 32 1.6 0.18 6.1 1.6

168 78 1.6 20 5.0 0.15 7.8 1.1

OVERALL AVERAGE 1.7 29 1.1 0.13 5.4 1.9~(Surface values from 1-3 meters deep.) "

48

contains some evidence that a real difference could exist (Table IX).

No clear-cut mechanism has been proposed to explain the difference.

Jenne (13) proposed hydrous oxides of iron and manganese as a possible

control by coprecipitation for the amount of dissolved iron, manganese,

copper, cobalt, and nickel in soils and fresh water. River and stream

inputs from the Straits of Juan de Fuca and the Columbia River contain

these hydrous oxides and probably form more on mixing with sea water,

thus providing a source for the hydrous oxides. It seems likely

therefore, that the mechanism may also apply to sea water. Simple

dilution effects are not enough to explain the decrease. Salinity

changes only 1-10% but the element concentrations change from 10-50%

between coastal and mid ocean samples. The above mechanism may not

explain the entire decrease, as organic and sulfide complexing,

precipitation, and adsorption may also contribute to the removal. These

are thought to be the major factors in the removal of trace elements in

Long Island SOlIDd (29). Although no complete explanation is known, the

difference does exist according to the data and provides an opportunity

for further productive research.

Tables X and XI show how the trace element concentration varies

with latitude for each water column. The coastal and mid ocean samples

are treated separately because of the differences already discussed.

Little regular change with latitude is observed, but some trends are

evident. Iron and cobalt show a decrease with decreasing latitude for

the mid ocean samples. Changes are not observed for coastal samples

because of the relatively small area sampled (Figure 1). There seems

to be no correlation with latitude for any element from coastal

49

sampling.

Tables XIII and XIV show variation of concentration with depth.

There is a definite increase in uranium and nickel with depth for the

mid ocean samples (also see Figures 10 and 11). TIle other elements do

not show a regular variation with depth. The variation is still

evident for uranium in the coastal samples. Biological activity in the

form of incorporation of uranium in the calcareous tests of various

microorganisms (1,2) is the probable explanation for the uranium

variations. When the microorganism dies, its test sinks down the water

column and begins to dissolve (22). In dissolving it will release the

uranium and thus cause a transport of uranium from upper water levels to

deeper ones. Nickel is also concentrated by planktonic organisms (9)

and is released both through excretion and decomposition upon death of

the organism. The latter process could yield a net transport of nickel

from upper to lower water levels. Other metals, such as copper and

cobalt are also concentrated in organisms. It is not known why these

do not show similar trends.

Tables XV and XVI show concentration variations with water mass.

Figures 12 and 13 show samples in relation to water mass. Figure 12

was prepared from Johns Hopkins Oceanographic Studies No.2 (28).

Figure 13 was prepared by assembling data from a number of sources

(7,21,24,25,26). In the case of the latter figure, there is a time

-dependence for the water masses. From late spring until early fall,

the Columbia River plume extends out and then curves south along the

coast. It is separated from the coast by another coastal current (21).

In late fall to early spring most of the plume is blown north by the

TABLE XIII. VARIATION OF TRACE ELEMENT CONCENTRATION WITH DEPTH (160 0 W)

Depth in Elements concentration ~g/liter

Meters Uranium Copper Nickel Cobalt Iron Manganese

Surface* 3.0 32 2.3 0.27 6.1 20

50-400 3.2 35 3.5 0.22 6.7 14

500-1300 3.5 16 3.4 0.24 6.2 22

1900-2500 3.7 54 3.7 0.25 5.5 15

*Surface means 1 to 3 meters depth.

V1o

TABLE XIV. VARIATION OF TRACE ELEMENT CONCENTRATION WITH DEPTH (125°W)

Depth in ELEMENT (concentration in ~g/liter)

Meters Uranium· .COpper .. Nickel· .Cobalt .Iron Manganese

Surface* 1.5 38 1.0 0.14 5.2 1.6

50-100 1.4 25 1.5 0.14 5.8 2.1

200-400 1.6 28 0.97 0.12 5.1 1.5

600-800 1.7 25 1.5 0.16 5.5 4.3

900-·1200 1.9 33 1.1 0.11 4.4 0.70

*Surface means 1 to 3 meters depth.

VII-'

NickellJg/l 4

~=='r-~a ~""':'\..\'~...:.:; .

-'..J<->,4

\, -r-¢- ......'-=0,,,

n _~

o

500 [::2

1000

2000 f:.<o

2500

(J)}-lOJ.wOJ~

P.r! 1500 I."

.d.w~

A

2500

200) 1=

Copperpg/1

o 20 40o r ~" ...- "C'~=~~'-D::''':~~\'«}~='':''''''':

'-./,~r-

, ~ "'='

500(",. VA~-

.;-~.rc-.z....~!";%.;n~'","1000 [=..., \. -b-

1500 k~

(J)}-l(j).wOJ~

.~

-Ep,OJA

eu=-=-0....~-~~·

UraniumlJ8/ 1

024oI- -,,, ,c -_. -~--~_: c'-r- ~'OU'=-'\)=~~i!~-=-~/:~~

\'\

cr.?=-,:,--=q- \.

, cn=z={)~n,.",.n,~~

500

I2500 It."

1000 ,."

(J)

I}-lOJ.w I<V~,

l.~ 1500.d I.wp,OJ IA I

II

2000lr

FIGURE 10. CONcmfr:~TION OF URANIUM, COPPER, AND NICKEL IN RELATIONTO DEPTH FOR COASTAL (---) AND NID OCEAN (~) HATERS.

Intv

500 I=»

ar..:('-;'-'=.~u-~

o

15001=

2000["

·2500 '=>

UlHoJ~

...~.....,

.~

.r:i~

PIOJ

t=1

Ironllg/l

4 8oOJ""'"'-.."tt '·_~"'U~O;~~~~--'v L _. .,

--J-,,,,\r,

C'\.;~ I'._r,\.c.o:a-, '-'",

~~~

500 ~'u>

2000 htl

2500 0,

~ 1000 I'"OJ~

OJ;:E:

s::.,-j

.d J.500 1'0:>~

~t=1

Cobaltllg/l

o 0.2 0.4o r..,,~,~,u,~,,-,('.;n=U~l--=-'~-U~~

_ .. r\.a.;.»yI

-<in,

\-1-~,"-l.-

~"' r_~. ",,

2000 1=

-u-2500 c.,

~ 1000 (zo ~-d~-OJ~

qj::>-1

s::'d 1500 I','

.c~p.OJ

t=1

FIGURE 11. CONCENTRATION OF COBALT, IRON, AND MANGANESE IN RELATIONTO DEPTH FOR COASTAL (---) AND HID OCEAN (_) HATERS.

\JlW

Degrees North Latitude 54

_200

~r600

~t,.800

o

II

00o

~Llooo~

0 ,,!

I _2000

0 00 0

3000

o

o

Geo 0

000

20

~--O-C<J>--..:J-;:>-,-~~~-\

IV 1 VI 35.2

FIGURE 12. POSITION AND DEPTn OT? SEA T'!ATER SAHPLESCOHPARED TO THE MAJOR HATER Y~SSES

SALINIl:Y iN 0/00

TABLE XV. VARIATION OF TRACE ELEMENT CONCENTRATION WITHRESPECT TO WATER MASS (160 0 W)

S %0 Water ELEMENT cortcerttratiort"irtug/1iterRange Mass* Uranium Copper Nickel Cobalt ,

Iron Manganese

34.4-34.8 I 5.0±0.5 51±9 3.6±0.6 0.32±O.O3 6.0±0.9 21±5

34.0-34.4 II 3.4±0.3 26±6 3.6±0.6 0.23±0.03 6.2±0.7 24±5

33.6-34.0 III 2.8±0.1 26±8 2. 7±0.1 0.19±0.04 6.8±1.1 11±2

34.8-35.2 IV 2.1±0.4 60±6 2.3±0.3 0.13±0.04 3.3±0.3 2.7±0.3

35.2-35.4 V 3.2±1.0 23±3 1.8±0.5 0.15±0.01 3. 9±0. 3 15±4

33.2-33.6 VI 3.8±0.8 38±4 3.4±0.3 0.52±0.15 7.2±0.7 50±5

32.8-33.2 VII 3.8±0.3 47±3 2.2±0.1 0.39±0.02 9.4±2.5 5.7±1.3

32.4-32.8 VIII 2.6±0.1 28±5 2.1±0.1 0.29±0.01 9.5±1.0 18±3

*See Figure 12.

V1V1

56Degrees North Latitude

50 49 48 47 46 45 44 43 42

~i.I 1((31r'1

. ) D1"'1 ----r-

33 ......

0 20034

0

0 0 0 0 400

B

UJl-l

0 600 aJ.waJ......

0"-<

34.5 _ ~ ~(} ,,-1

I ..c! .wi P-

OaJ

0 0 800 A

A

1000

--1200

I1-1------------------.....1-1400

FIGURE 13. LOCATION AND DEPTH OF SA~LES COLLECTEDALONG THE WEST COAST OF TIill UNITED STATES (125°W).

ISOHP.LINES ARE ALSO SHOWN WITH SALINITY IN 0/00.

"

TABLE XVI. VARIATION OF TRACE ELEMENT CONCENTRATION WITHRESPECT TO WATER MASS (12SoW)

S 0/00 Water ELEMENT concentration in pg/liter-Range Mass* Uranium Copper Nickel Cobalt Iron Manganese

34.5-35.0 A 1.9±0. 3 33±5 1.4±0.2 O.lS±0.03 5.3±0.S 2.9±1.4

34.0-34.5 B 1. 7±0.1 27±6 1.1±0.1 0.14±0.01 5.4±0.4 0.64±0.1

33.0-34.0 C 1.S±0.2 2S±2 0.64±0.2 0.09±0.02 4.6±0.6 1. 6±0. 8

32.0-33.0 D 1.6±0 .1 24±4 1. 2±0. 2 0.lS±0.03 6.4±0.7 2.3±0.S

29.0-30.0 F 1.4±0.3 38±8 0.74±0.1 0.12±0.01 S.1±0.8 1.6±0.8

31.0-32.0 H 1.6±0.1 39±9 1.2±0.2 0.17±0.01 6.l±0.8 1. 6±0. 3

30.0-31.0 I 1. 2±0.1 26±4 1.0±0.4 0.18±0.OS S.2±0.8 1.4±0.1

*See Figure 13.

Ul-....J

58

winds. Since the samples were collected in mid-October, 1967, the data

for the figure were averaged over the years 1963 to 1966 for this time

of year. The data are representative of the isohalines in the upper

100 meters, but some variation would be expected as the plume is not in

a reproducible area each year.

In addition to the Columbia River plume, there is another very

important water structure known as a halocline, off the west coast of

the United States (7). A halocline is a water "layer showing a rapid

increase in salinity with depth. The top of the halo cline is at 100

meters and has a salinity of 33 0/00 and the bottom is at 200 meters

with a salinity of 34 0/00. Since the halocline is stable with respect

to time, water above the halocline can mix only slowly, if at all with

water below it. This isolation from mixing should yield a difference

between the two regions. Table XVII shows there is a difference in the

concentrations of the trace elements, except for manganese but this

difference is small compared to the data spread in eaCh region. The low

trace element concentrations found within the halocline (Table XVII)

are possibly due to the high productivity associated with such an area

(32).

The Columbia River plume is represented in Figure 13 by water

masses E, F, and G. Water mass H is probably a mixture of low salinity

water from the Straits of Juan de Fuca and the Columbia River. One

source has described the Columbia River plume as water with a salinity

less than 32.5 0/00 (20). In Figure 13, water with a salinity less

than 32 0/00 clearly shows a cross section of the plume between 46°N and

44°N. Only two samples were obtained from this area, both from water

TABLE XVII. TRACE ELEMENT CONCENTRATION ABOVE, WITHIN, AND BELOW THE HALOCLINE

Position with respect ELEMENT concentration in ~g/l

_____t_o_Ha1oc1ine Uranium Copper Nickel Cobalt Iron Manganese

r{:~

Above

Within

Below

1.4±0.1

1.3±0.1

1. 7±0.2

32±6

24±3

28±3

1.3±0.2

0.83±0.2

1.5±0.1

0.15±0.01

0.13±0.01

0.13±0.02

5.7±0.5

5.4±0.5

5.1±0.3

1. 7±0.3

2.0±0.7

1. 7±0. 7

U11.0

60

mass F. Table XVI shows F to be low in all elements except copper which

is high. Water mass I is also low including copper. Water masses A,

B, C, and D show a trace element distribution similar to the depth

distribution, as expected, as approximately the same grouping of samples

was used for each. It is interesting to note that D and H could be

considered very similar and indeed, the uranium, nickel, cobalt, and

iron content is very similar. In general, there was a sm~ll but

observable difference in certain trace element concentrations between

water masses for the coastal waters.

The differences in the mid ocean waters are more readily observable

as Figure 12 and Table XV show. The m03t obvious difference is between

water masses II and III. Samples from III are from approximately the

same depth as II and yet the difference is distinct for all elements but

copper. Copper and manganese values are extremely variable and

differences given in Table XV mayor may not be reaL The copper value

of IV and the manganese value of VI ~re thought to be anomalously high.

Water masses VI and VII have higher trace element concentrations in

general than IV and V even though the latter have higher salinities.

This indicates a latitude relation which may have been masked by deep

water samples included in Table IX. High latitude samples also have a

higher iron content than deep water samples, and there also seems to be

an inverse relationship between the other elements and iron for VI, VII,

and VIII. In general, for the mid ocean samples, there is a distinct

difference between water masses which appear significantly larger than

differences in salinity.

61

Fresh Water Data

The fresh water samples were analyzed to ascertain their dissolved

and particulate trace element content. Table XVIII shows the results of

the analysis of these samples for filtered and unfiltered water and

particulate matter. Each sample was analyzed twice, first a 500 ml

unfiltered sample followed by a 500 ml sample filtered through a 0.45

micron pore size membrane filter. The filters were later analyzed

directly by x-ray fluorescence spectrometry. The particulate values

were estimated from the total number of counts, the area excited by the

primary beam, the total area covered by the particulate matter, and the

counts per microgram obtained from the standards. The background for

each element was obtained by measuring the background of an unused

membrane filter. Although the above is an estimate, it is probably

accurate within ±20%.

Both filtered and unfiltered samples were analyzed to determine if

the same amount of metal was extracted in each case. Table XVIII shows

unfiltered sample values are higher than filtered values in most CL:.1':'8.

Thus comparisons between analyses must be made only between filt~ -.'"..:

samples or unfiltered samples.

Lake Waiau was analyzed and was found to have very high part'ic"~;;'~"~·

values for iron and manganese, and relatively high values for the

unfiltered sample, at least, when compared to water from the Douglas

cinder cone. In fact all elements except uranium are higher in Lake

Waiau than in Douglas. Since both Waiau and Douglas have the same

water source, rain and snow, the higher extractable trace element

content of Waiau may be due to the larger algal population of Waiau.

TABLE XVIII. RESULTS OF FRESH WATER ANALYSIS(CONCENTRATION ~g/l)

62

Uranium Copper Nickel Cobalt Iron Manganese

Lake Waiau

Particulate 1.2 740 52Unfiltered 1.2 9.8 1.4 0.14 26 11Filtered 1.6 9.6 1.2 0.07 4.7 1.5

Perched water (Douglas)

Unfiltered 1.2 5.6 0.48 0.07 1.6 0.24

Lake Champlain

Particulate 18 3.2 12 142 30Unfiltered 1.6 3.4 0.92 0.26 14 18Filtered 1.0 3.2 0.78 0.06 1.4 1.7

Conneaut Lake

Particulate 2.2 0.20 0.45 6.0 17Unfiltered 0.6 1.8 1.6 0.14 5.5 21Filtered 1.3 1.6 0.52 0.12 1.6 4.6

Mahoning River

Particulate 2.9 2.5 6.7 104 10Unfiltered 2.0 0.2 35 0.58 12 350Filtered 1.8 1.8 33 0.62 16 360

Shenango River Reservoir

Particulate 2.7 0.60 1.4 22 28Unfiltered 0.7 3.4 2.0 0.06 6.1 37Filtered 1.1 2.4 1.2 0.28 0.65 7.6

Spring water

Particulate 2.2 0.25 0.32 2.8 0.45Unfiltered 0.5 2.4 0.02 1.4 0.76Filtered 0.6 6.8 2.0 0.02 0.58 2.1

63

A possible reason for the difference in algal populations is given in

tae Introduction but not yet been substantiated. It may be argued that

if this were not the case, one would expect approximately the same trace

element concentrations in both lakes, as the source of trace elements

for each must be similar, if not identical.

There seems to be some correlation between dissolved trace element

concentrations and the concentrations of the elements in the lava.

Hawaiian lavas are about 6-9% by weight iron as FeO and 0.1-0.2%

manganese as MIlO with other elements in the parts per million range

(32). This, of course, refers only to the elements considered in the

study. The high values for iron and manganese should be reflected in

the waters associated with the lava. The effect is noted to some

extent for dissolved material in Waiau, but is much more evident for

particulate material. Table XIX compares the element to iron ratio of

lavas and the particulate and dissolved material for Waiau and Douglas.

All metals in the table show an enrichment with respect to iron,

especially copper. The ratios of the lake waters, except copper, agree

within a factor of 10 to 50 with the ratios of the lavas, thus,

indicating that the lavas play a role in the trace element supply for

these waters. The high copper ratios are interesting and warrant

further research.

The other fresh water samples were chosen to represent as wide a

variety of bodies of water as possible, to test the applicability of the

method to various waters. Their trace element concentrations are shown

in Table XVIII and the locations are shown in Figure 3. Lake Champlain

is a large lake about 100 miles long and 1-10 miles wide with little

TABLE XIX. COMPARISON OF ELEMENT TO IRON RATIO FOR HAWAIIAN LAVAS,LAKE WAIAU, AND DOUGLAS PERCHED 'vATER

Hawaiian Waiau Waiau Waiau DouglasRatio, Lavas Particulate Unfiltered Filtered Unfiltered

Mn/Fe 1. 6x10- 2 7.0x10-2 4.0x10- 1 3.0x10- 1 1.5x10- 1

Ni/Fe 6.4x10- 3 --- 5.4x10- 2 2.5x10- 1 3.0x10-2

Co/Fe 5.6x10- lf 1.6x10- 3 5.4x10- 3 1.4x10-2 4.3x10- 2

CufFe 1.7x10- 3 --- 2.0 2.0 3.5

0'~

65

heavy industry bordering it and only moderate recreational use of its

surface area is ~dde. Conneaut Lake is a small lake about 3 miles long

and I mile wide with heavy recreational use for its surface area in the

summer which is surrounded by a large number of both permanent and

summer homes. The Mahoning River is a small river which flows through

the industrial complex of Warren and Youngstown, Ohio, and New Castle,

Pennsylvania. The Shenango River Reservoir is a three year old man-made

lake about 15 miles long and with a maximum width of less than a mile.

The reservoir is formed before the Shenango River flows through any

heavy industry. The spring is located in the mountains of Western

Pennsylvania and has a flow rate of about 30 gallons per hour.

Since the sample from Lake Champlain was collected near shore while

the lake was rough, there was considerable suspended sand, organic

matter and clays in it. Some of this material settled quickly but the

sample was shaken before filtering to get an overall sample of the

suspended matter. The presence of the sand particles is the probable

cause of the high values for the particulate analysis of the lake. This

material will cause increased scattering of the primary x-rays and

therefore an apparent increase in the intensity for each element. The

uranium value of 18 ~g/l is highly suspect. The ~ radiation of the

particulate and standard samples was counted and indications were that

the actual uranium content is about an order of magnitude less. Good

~ spectra were impossible to obtain because of the large ~ energy

absorption of the samples. There seems to be little distinct

difference between the filtered samples of this lake and Conneaut Lake

despite the different lake environments.

66

The Shenango River Reservoir has generally more dissolved and

particulate matter than Conneaut Lake. Both bodies of water were in

late summer algal bloom) but the reservoir population was estimated to

be 4 times greater than the lake population. Reflectance spectra of

particulate matter on the filters have been used to make the estimate

(31). The difference may explain part of the trace element content

variation between the bodies of water) but most of it is probably due

to the different water sources for each. Conneaut Lake is both spring

and stream fed) whereas, the reservoir is river fed. Because the river

carries a higher dissolved and sediment load, one would expect the

reservoir to contain more dissolved and particulate material. The

recent nature of the reservoir may also be a factor in the difference.

The spring water is clear, cold, and excellent drinking water

serving a group of hunting and summer cabins (about 15), 80-90 miles

north of Pittsburgh, Pennsylvania. The Mahoning River is used for

dumping raw and treated sewage, steel mill wastes) and as cooling water

for steel mills and other industry along about one fourth of its entire

length. The effect of this use can be seen in the trace element

content. The high particulate iron and very high dissolved manganese

and nickel values could probably be traced to the iron and steel

industry. The sample was collected about 10 miles below the last steel

mill and about 3 miles above New Castle, Pennsylvania. It would be

most informative to sample this river every quarter mile to learn the

source of the metals and how long the material stays in the water. The

spring water is low in all elements except copper and nickel.

67

The work with f1"esh water samples indicates that the extraction

method can be used to trace certain types of pollution and possibly to

characterize water sources by trace element content.

SUMMARY

A method was developed to analyze for uranium, copper, nickel,

cobalt, iron, and manganese in both fresh and sea water. An 8-hydroxy­

qUinoline-chloroform extraction and x-ray fluorescence spectrometry

were used in the analysis. Absolute methanol, 8-hydroxyquinoline,

and chlorofo~ were the only reagents needed for sea water analysis and

the equipment needed for the extraction and primary evaporation was

simple and portable, thus, shipboard and field work could be done.

The precision of the method depended on the element and the

absolute amount of the element being analyzed. The analysis of a 500 m1

sample of sea water had a precision of 5% for all elements except

uranium and cobalt, which were 10%. AlSO m1 sample had a precision of

10% for all elements except uranium and cobalt, which were 20% and 30%

respectively.

The actual sea water analyses for this research were carried out

on 120 m1 and 240 m1 samples from, respectively, the mid North Pacific

Ocean off the Northwest Coast of the United States (125°W). Coastal

water trace element content was found to be lower than mid ocean content.

Significant differences in trace element content were also found between

water masses of differing salinity, but little regular variation with

latitude could be found. Some elements, notably uranium, showed an

increase in concentration with depth.

The method proved to be applicable to a wide variety of fresh

waters, ranging from spring water to polluted river water. The large

algal population apparently present in Lake Waiau appeared to have the

effect of increasing the extractable trace element content of the lake

as compared to Douglas perched water, where such a population was

absent. Other fresh water samples showed evidence of differences

related to the water source and possible pollution.

69

APPENDIX I

METHOD USING DITHIZONE-CELLULOSE ACETATE COLUMNS

Cellulose acetate (Fisher Scientific Co.) with a particle size of

0.4-0.8 rom is treated with a 0.01% solution of dithizone in carbon

tetrachloride and the carbon tetrachloride removed in a vacuum rotary

evaporator. This material was used to make columns which were

approximately 2 cm in length and 1 cm in diameter with a 3 rom thick

layer of powdered cellulose on the bottom. A 2 m1 filtering funnel

made an excellent container for the columns. The column was wet with

about 0.5 m1 of carbon tetrachloride, washed with 50-60 m1 of one normal

hydrochloric acid, and rinsed with deionized water. The hydrochloric

acid wash was necessary since recovery was very poor without it.

The water sample was adjusted to a pH of 7.00 ± 0.05 and passed

through the column at a rate of one to two liters per hour. The bulk

of the carbon tetrachloride was removed by drawing warm air through the

column for several minutes. The column material was removed from the

filtering funnel using a Teflon coated spatula and placed in a glass

vial. It was dried on a 100°C hot plate. The dried material was

transferred to a mortar and ground to a powder, which was compressed

into a 1.27 cm pellet about 3 rom thick at a pressure of 30 T/in2 •

Since the pellets were too small to be held by the sample holder of the

x-ray instrument, a set of Teflon rings of the proper size was

constructed to accommodate and position the pellets.

APPENDIX II

CALCULATION OF CRITICAL DEPTH FOR CHROMIUM X-RAYRADIATION IN THE CELLULOSE ACETATE PELLET

This calculation is based on an equation derived by Liebhafsky,

et ale (14).

(1) Id = 1 _ e-apd

100

Where: Id = intensity from a sample of thickness d

I = intensity from an infinitely thick sample00

a = 111 csc8l + 112 csc62

111 = average mass absorption coefficient for incomingbeam

112 = average mass absorption coefficient for outgoingbeam

81 = angle of incidence

62 = angle of emergence

p = density of matrix

d = depth in cm.

For purposes of calculation the following assumptions are made:

1. Only absorption effects are considered

2. The matrix is effectively 100% cellulose acetate

The other quantities in the equation have the following values:

(]

72

].11 = 0.1

].12 = 26

81 = 67 0

82 =nnOL:.J

p 1.0 g/cm3

Upon substitution of the above values into equation (1), the

critical depth is found to be 0.1 rom for chromium radiation. The

critical depth will increase with increasing atomic number. In pellet

work a maximum depth will be reached for the element zinc and will be

aoout 0.2 rom.

When these values are compared to the total thickness of the

cellulose acetate pellets (3 mm), it is clearly shown that only a small

percentage of the total pellet (3%) is excited by the x-rays. Since a

pellet weighs approximately 0.5 grams and the minimum amount of cobalt

that can be analyzed with precision is 0.02 ~g, the concentration of

cobalt in the pellet would be 1.2 ppm or 0.6 ].Ig in absolute amount.

This would require a 2 liter sample of sea water based on the mid ocean

value found and the amount of zinc and copper in such an amount would

completely swamp the column. About 500 m1 of sea water is the most

that can be analyzed for copper and zinc. It is, therefore, impossible

to use this method to analyze for cobalt. The same type of argument

may be applied to nickel and chromium, so the pellet method was

abandoned.

APPENDIX III

NEUTRON ACTIVATION DETECTION LIMITS

The detection limits for neutron activation analysis were

calculated from the following equation:

(1) A = N 0 a % abundance (1 _ e-At )100

A = activity in disintegrations per minute

N = number of atoms

o = neutron flux in neutrons/cm2 /sec

a = cross section in cm2

A = decay constant

t = irradiation time in hours

A number of assumptions must be made in order to use the above

equation.

A = 10 dpm

N grams x 6.0xl0 23

Atomic Weight

f/J = 5xlO 12n/cm2 /sec

a = barns x 10-2 4 cm2 /b arms

A _ 0.69 • t 1/2 = half-life in hours--~

t 1/2

t = 0.082 hours

An irradiation time of five minutes is us<?·d to prevEmt any sodium

chloride carried through the procedure from becomin~~too radioactive.

74

The detection limits of all elements except Fe58 would increase with

longer irradiation times. Iron 58 would not increase because of the

long half-life of Fe59 • An element reaches one half maximum activity

when irradiated for one half-life and an infinitely longer irradiation

only doubles the activity. For this reason irradiations longer than

one half-life are not useful.

Uranium analysis is assumed to be by the n,Y reaction not by

fission, although fission will certainly take place. In the case of

Fe 59 decay takes place by both Sand Y emission in about equal parts

with a further equal split in the gamma energies, therefore, the

detection limit is four times higher than calculated from equation (1).

75

ISOTOPE % CROSSELEMENT ACTIVATED ABUNDANCE SECTION

uranium U238 99 2.7 barns

copper Cu63 69 4.5 "nickel Ni64 1.1 1.5 "

cobalt Co 59 100 18 "iron Fe 58 0.33 1.2 "manganese Mn 55 100 13.3 "

ISOTOPEELEHENT produced in n, a HALF LIFE

REACTION

uranium U239 23.5 min

copper Cu64 12.9 hr

nickel Ni65 2.56 hr

cobalt Co 6O 10.5 min

iron Fe 59 45 d

manganese Mu 55 2.58 hr

The above tables give the information needed to use equation (1) to

calculate the data given in Table I.

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