Editorial Manager(tm) for Journal of Radioanalytical and Nuclear Chemistry Manuscript Draft Manuscript Number: JRNC1907R1 Title: Determination of uranium, thorium and potassium contents of rock samples in Yemen. Article Type: Manuscript Keywords: U, Th, and K; γ-spectrometry; INAA and XRF; rocks; Yemen. Corresponding Author: A. Abdul-Hadi, ph.D. Corresponding Author's Institution: Atomic Energy Commission of Syria First Author: A. Abdul-Hadi, ph.D. Order of Authors: A. Abdul-Hadi, ph.D.;W. Al-Qadhi;E. El-Zeen, ph.D. Abstract: Uranium, thorium and potassium contents in sixteen different rock samples from various sites in Republic of Yemen were determined using three different techniques of analysis: -spectrometry, INAA and XRF. The concentration range for thorium, uranium and potassium were found to be from 9810 ± 272 to 3.6 ± 1.3 ppm, 1072 ± 40 to 1.2 ± 0.7 ppm and 11 ± 1 to 0.26 ± 0.05 %, respectively. Response to Reviewers: Dear Mr. Braun Thank you for your E-mail concerning my manuscript, "Determination of uranium, thorium and potassium contents of rock samples in Yemen." submitted to Journal of Radioanalytical and Nuclear Chemistry. Pleas find the revised manuscript with the results discussion in comparison to the recent papers already published in your journal. With best regards, Dr. Abdulrahman Abdul-Hadi

1

Determination of uranium, thorium and potassium contents of rock

samples in Yemen

Abdulrahman ABDUL-HADI1, Wedad Al-Qadhi

2. Enayat El-Zeen

2

1: Chemistry Department, Atomic Energy Commission of Syria, P. O. Box 6091 Damascus Syria

2: Physics Department, Damascus University

email: cscientific5@aec.org.sy

Abstract

Uranium, thorium and potassium contents in sixteen different rock samples from various

sites in Republic of Yemen were determined using three different techniques of analysis:

-spectrometry, INAA and XRF. The concentration range for thorium, uranium and

potassium were found to be from 9810 ± 272 to 3.6 ± 1.3 ppm, 1072 ± 40 to 1.2 ± 0.7

ppm and 11 ± 1 to 0.26 ± 0.05 %, respectively.

Keywords: U, Th, and K, -spectrometry, INAA and XRF, rocks, Yemen.

Introduction

The study of naturally occurring radioactive materials (NORM) is of great interest to

many fields of Earth sciences, most of them involving the determination of the U, Th and

K content in rocks. The natural environmental radiation mainly depends on the type of

parent rock: higher radiation levels are associated with igneous rocks such as granites

pegmatite and monazite veins. There is some evidence that radioactivity in granites is

often linked to fluorite occurrences1.

The average abundance of thorium in the Earth’s crust is about 5.6 ppm, but thorium is

highly enriched in the upper crust with an average concentration of 10.5 ppm, while the

middle crust has an average of 6.5 ppm2, and the lower crust with an average of 1.2 ppm.

High thorium concentrations (200 – 1000 ppm or higher)2-5

may be present in soils, clays,

laterites, and bauxites developed on alkaline rocks, high heat-producing granites,

carbonatites, and in the vicinity of thorium-rich pegmatite and veins. The concentration in

uranium and thorium can vary from 10-12 %wt but can be as high as 26.4 %.in uranium-

and thorium rich monazite2,5-7

.

There were many studies focusing on the exploration of radioactive anomalies in Yemen,

which is mainly located on the Southwest of the Arabian Peninsula. In 1984-1985,

airborne radiometric measurements were carried out for Republic of Yemen by Geosurvey

Limited and then completed by Rebertson Group, and made a radiometric map of

Yemen8. Also, in 1987, Total Company explored the radioactive minerals in Suda'a and in

Taiz, which are located in the North and Southwestern part of Yemen9. The reported

results show that the radioactive minerals are concentrated in the ironic curst of the

Alwajidah sandstones and pegmatite veins. Then, in 1999, Yemeni Geological Survey and

ManuscriptClick here to download Manuscript: Determination_of_uranium,_thorium_and_potassium_contents_of_rock_samples_in_Yemen.doc

2

Mineral Resources Board (GSMRB) made a comprehensive field surveys for some sites,

which the airborne gamma-ray survey show that they are good candidates as radioactive

anomalies resources. The field surveys show that the radioactive anomalies are mainly

associated with granite and pegmatitic veins10

.

Experimental

Geological Setting and Description of the Samples In this work, sixteen rock samples were obtained from (GSMRB).The samples were

collected from five different sites as follows:

1- Samples 1-6, 13, 15 were collected from Juban, which is located on the southeastern

part of Sana'a. The area is mainly covered by granite rocks and gneiss.

2- Sample 7 was collected from Saber Mountain with the altitude of 3200m, which is

located in Taiz city (south of Sana'a) and the sample is composed of granite.

3- Samples 8 and 10 were collected from Al Mahfid, which is located in the eastern

part of Aden. The area is mainly covered by Pre- Cambrian granites with some

Cretaceous sandstone.

4- Samples 9, 11, 12 and 14 were collected from Haifan- Taiz, which is located in the

southern part of Sana'a and this area is covered by igneous, metamorphic, and granitic

rocks and pegmatitic veins.

5- Sample16 was collected from Mareb which is located in the eastern part of Sana'a.

The vast majority of this area is covered by quaternary sand dunes, alluvial sand, and

gravel deposits. It should be mentioned here that the southwest area of Sana'a is mainly

covered by Cambrian rocks and volcanic rocks. Figure 1 shows the map of Yemen and

illustrated the locations of collecting the different sixteen samples.

Figure 1 The map of Yemen and sampling locations

3

The samples were analyzed by X-ray Diffraction XRD using STOE STADI P

diffractometer with the monochromatic CuK1 radiation (= 1.5406 Å), in order to

identify their crystal structure and all the recorded results are summarized in Table1.

Table 1 Samples Description

Sample no Location Field description Main metallic phases

1 Juban-hamoraa granite-pegmatite veins Quartz(SiO2)-Magnetite(Fe3O4)

2 Juban-Naween granite-pegmatite veins Quartz(SiO2)

3 Juban-Sawad granite Quartz(SiO2)-

Hornblende(NaCaFe5Si8(OH)2)

4 Juban-Nawaa granite-pegmatite veins Quartz(SiO2)- Magnetite(Fe3O4)-

Pyroxene- Augite(Ca(FeMg)Si2O6)

5 Juban-Goleen granite-pegmatite veins Quartz(SiO2)- Magnetite(Fe3O4)-

Putite

6 Juban-Goleen granite-pegmatite veins Quartz(SiO2)- Magnetite(Fe3O4)

7 Saber Mount. gray-white granite Quartz(SiO2)-Feldspar

8 Al Mahfid granite-quartz- feldspar Quartz(SiO2)-Albite(NaAlSi3O8)

9 Haifaniz Ironic granite veins Quartz(SiO2)- Feldspar

10 Al Mahfid Quartz- Feldspar Quartz(SiO2)-Albite(NaAlSi3O8)

11 Haifan Green-Indizet rock Quartz(SiO2)- Feldspar

12 Haifan granite-quartz- feldspar Quartz(SiO2)-Albite(NaAlSi3O8)

13 Juban-Spah limestone

14 Haifan- Taiz granite-quartz- feldspar Quartz(SiO2)-Albite(NaAlSi3O8)-

Amphibole

15 Juban- Somaah granite-pegmatite veins Quartz(SiO2)- Magnetite(Fe3O4)-

Augite(Ca(FeMg)Si2O6)

16 Mareb granite Quartz(SiO2)-Albite(NaAlSi3O8)-

Amphibole – Magnetite(Fe3O4)

Gamma ray spectrometry

The collected rock samples were crushed, sieved and packed in cylindrical disc of 7 cm

dim and 1 cm height, and sealed for four weeks to reach the secular equilibrium between 226

Ra, 224

Ra and their daughters for gamma ray measurements. The -ray spectrometer

consist of a 60% HPGe (n-type) detector with a resolution of 2.2 keV at 1332 keV

photopic of 60

Co.

The energy and efficiency calibrations were done using a soil

radioactive standard source containing mixture of 241

Am, 109

Cd, 57

Co, 137

Cs, 60

Co, 113

Sn,

and 88

Y (UKAS Calibration, QCY48, soil. No. R8/3/7). The samples were counted (three

times each) for a convenient time to their activity (19 hours for samples with low activity

and 2 hours for samples with high activity).

4

Uranium was identified based on its daughters transitions 210

Pb (46.54 keV), 234

Th (63.3

and 92.8 keV), 226

Ra (186.21 keV), 214

Pb (295.22 and 351.93 keV), 214

Bi (609.32,

1120.29, and1764.4 keV) 11, 12

.

Thorium was identified based on its daughters transitions11, 12

212

Pb (238.63 keV), 228

Ac

(338.32, 911.21, and 968.9 keV), 208

Tl (583.19 and 2614.5 keV)

Potassium was determined based on its gamma transition of 1461 keV.

The specific activity A was calculated for each photopeak Eγ as:

mt

S

* (1)

Where: S is the net peak area, ξγ: is the efficiency, Iγ is the relative intensity, t is the live

time of sample collection, and m is the sample mass in grams. In each spectrum, U and Th

were determined by taking the average of all considered -lines and the activities of 238

U, 232

Th, and 40

K were converted into concentrations according to the following equation:

EAE

EEE

FC

,

*

(2)

Where CE is the fraction of element E in the sample, ME and E are the atomic mass (gr

mol-1

) and the decay constant(s-1

), respectively, of the corresponding radionuclide

considered (238

U, 232

Th, or 40

K), NA is the Avogadro’s number, A,E is the isotopic ratio

for 238

U, 232

Th, or 40

K. F is a constant that converts the concentration into ppm or a

percentage, and AE is the calculated activity (in Bq gr-1).

The concentration of U, Th and K in each sample was calculated by taking the average

concentration of the three measurements.

The uncertainty in the calculated activity is due to: peak area S, background correction,

efficiency calibration, and sample mass. The full relative uncertainty A is calculated

by13

:

222

mSA

Where: S is the relative uncertainty of the corrected net peak area?

S

SS

22 )(,b

b

bsbsSt

t

σs+b is the absolute uncertainty of the net peak area in the spectrum, σb is the absolute

uncertainty of the corresponding net peak area in the background spectrum, ts+b is the live

time of sample collection, tb is the live time of background spectrum collection.

ηξ is the relative uncertainty of the efficiency calibration for the energy of the

corresponding gamma-line, and ηm is the relative uncertainty of the sample mass. The

uncertainty of the average activity is calculated as:

n

i

AiAn 1

21

Where: Ai is the uncertainty of the activity for each photopeak AAiAi

5

n is thee number of the photopeaks. The concentrations of 40

K, 232

Th, and 238

U for all

measured rocks are given in Table 1.The uncertainty values(Talbe-1) is based on a

standard uncertainty multiplied by a coverage factor k= 2.5, which for a t-distribution

with υ=2 degrees of freedom corresponds to a coverage probability of approximately

95%.

X-Ray Fluorescence

Five grams of each sample was analyzed by X-ray fluorescence, using EDXRF technique

to determine U, Th, and other major elements Fe, Zr, Y and Ti, and minor elements Nb,

Mn, Rb, Sr , Zn and Pb presents in the samples.

Instrumental Neutron Activation Analyses INAA

Two grams of each sample with high activity (samples 1-9) was analyzed by INAA in the

MNSR reactor with 5×1011

n/cm2s thermal neutron flux to determine U and Th

concentrations in the samples. The concentrations of U and Th measured by -ray

spectrometry, INAA and XRF, are given in Table 2.

Table 2. Concentrations of 238

U, 232

Th, and 40

K using γ-spectrometry and the

concentrations of U and Th, INAA, and XRF techniques

Th(ppm) U(ppm) K% Sample

XRF INAA -ray XRF INAA -ray -ray

9148±54 9177±552 9810±273 1405±24 954±50 1073±40 10.7±0.8 1

5798±44 5745±226 6409±180 705±19 715±30 766±22 9.6 ± 0.7 2

2624±22 2422±148 2305±64 314±12 306±18 324±8 2.91±0.23 3

2825±23 4093±248 3161±90 195±14 297±17 248±15 3.4 ± 0.7 4

262±15 285±17 308±6 73±9 112±7 82±2 3.2 ± 0.3 5

212±9 216±13 248±8 73±8 62±4 74±3 0.50±

0.15

6

85±7 122±8 126±5 32 ± 8 35 ± 2 40 ± 2 4.7 ± 0.4 7

33±5 - 37±2 - - 12 ± 1 8.3 ± 0.6 8

1819±17 1604±97 1719 ±129 14 ± 2 11 ± 2 12.9 ± 1.8 2.7 ± 0.3 9

23 ± 5 25 ± 3 < 5 4.6±1.1 0.74 ±

0.11

10

21 6 17±3 < 5 3.9±0.5 6.5 ± 0.6 11

< 20 16±4 < 5 2.0 ± 0.5 4.7 ± 0.5 12

< 20 < 3 < 5 2.1 ± 0.6 < 0.25 13

< 20 11± 2 < 5 1.5 ± 0.4 5.6 ± 0.5 14

< 20 3.6 ± 1.3 < 5 < 1 1.0 ± 0.3

0.12

15

< 20 4.8±0.7 < 5 1.2±0.3 4.9 ± 0.4 16

Results and Discussion

The concentrations of U and Th measured by -spectrometry, INAA, and XRF are in good

agreement with some exceptions observed for sample 2 and sample 4. The difference may

be due to the heterogeneous in the both samples.

The concentrations of U, Th, and K in the samples, which are measured by -

spectrometry, range from 1072±40 to 1.2±0.7 ppm, 9810±272 to 3.6±1.3 ppm, and 11±1

6

to 0.26±0.05 %, respectively. High concentrations of U and Th in 1-4 samples, which are

granite rocks, are higher than the average concentrations of U and Th in granite rocks( 4

ppm of U , and 15 ppm of Th)14

,and can considered as uranium and thorium-rich

pegmatite and veins. Similar observations were noticed in other areas such as: southwest

of England and Pikes Peak, Colorado15

, south-alpine pegmatite at Piona, Italy4, in the

western of Australia2, the eastern costal area of China

5 and in many other commercial

granite used in building such as in Greece16

and in China3.

The results of XRF analysis are shown in Table 3, which concerning the major elements

Fe, Zr, Nb, Ti and Y and the minor elements Zn and Pb present in the samples. The

mentioned analyzed elements have usually relation with U, Th and K. Other elements

such as Ca, Rb, Sr and Mn were analyzed but not mentioned in the Table-3 because of no

evident relationship with U, Th and K.

Table-3, XRF analyses of the samples

Pb

ppm

Zn

ppm

Y

ppm

Ti

%

Nb

ppm

Zr

ppm

Fe

% Samples

558 31 1935 134 11000

1000 1.470.11

17000

1000

24000

1000 29 2 1

441 27 779 57 4550 252 0.930.06 7597 423 13000

1000 16,2 0.9 2

115 9 451 35 2137 118 0.370.04 1668 93 6300348 4.220.23 3

212 16 564 40 3631 201 0.680.05 3507 196 8105449 7.0 0.4 4

75 15 1681 98 348 21 0.960.06 476 28 4006221 11.7 0.7 5

< 15 325 25 174 11 0.310.03 284 17 3701205 5.1 0.3 6

32 8 271 22 135 8 0.220.03 857 48 1157 64 2.34±0.13 7

85 6 < 30 35 6 0.200.03 44 4 22 3 0.18±0.01 8

64 11 60 18 35 6 0.460.04 < 10 787 47 2.980.17 9

< 15 < 30 20 2 0.140.02 < 10 < 15 0.140.01 10

< 15 73 17 53 4 0.330.03 72 9 465 27 3.450.19 11

< 15 < 30 36 3 0.320.03 13 3 561 31 1.720.09 12

< 15 < 30 < 10 0.370.04 < 10 16 4 0.430.03 13

< 15 82 15 484 0.320.03 18 4 528 30 1.490.08 14

< 15 90 18 263 0.950.06 37 3 196 12 5.9 0.3 15

< 15 33 4 88 7 0.160.01 < 15 < 15 < 0.030 16

It can be seen from Table-3 and the Figures 2 and 3, that the samples can be divided into

three separate groups: Group 1, consisting of samples 1-8, these samples were

characterized by a) high concentrations of Uranium and Thorium, b) most of them were

coming from JUBAN region (samples 1-6), c) granite-pegmatite veins or feldspar. d) The

Th/U ratios of the mentioned group lie within the range (3.15 - 12.7) e) a good

relationship between the higher concentrations of U and Th and the concentrations of Fe,

Zr, Y, Ti and Nb. A similar high concentration of U and Th in granite was observed in the

eastern costal area of China5, with ThO2 up to 10.1 wt% and ThO2/UO22.

7

Group 2 consisting of samples 10-16, this group are characterized by a) low

concentrations in U and Th. b) the ratios Th/U range from 1.4 to 8, c) there is no

relationship between U and Th concentrations and the other elements, but a clear

relationship between Fe, Zr, Ti, Zn and Y concentrations. Similar observations were

observed in Egypt17,18

and Saudi Arabia19

.

1

10

100

1000

10000

100000

0 5 10 15

samples

pp

m

U

Th

Y

Zn

Nb

Figure 2: the concentrations of the elements U, Th, Y, Zn and Nb in the different

samples.

1

10

100

1000

10000

100000

1000000

0 5 10 15samlpes

pp

m

Th

Zr

Fe

Ti

Figure 3: The concentration of the elements Th, Zr, Fe and Ti in the different samples.

8

Group 3, which is consisting of only one sample (no. 9) which was characterized by a

concentration of U at 12.9 ppm and Th at 1719 ppm and a Th/U ratio at 133.3. The

increase of the concentration of Th is associated with increasing of Fe, Zr and Ti.

Conclusions From field description and XRD analysis of the rock samples, it can be stated that: all the

samples are of igneous rocks origin. The main metallic phase in all samples is quartz

SiO2. Also, samples (1-9, 12, and 16) are granite and granite pegmatite. The

concentrations of Pb are in good relationship with U and Th. The relationship between the

concentrations of U and Th and the other elements are demonstrated and need to be

studied for a large number of samples and more elements

Acknowledgement The authors like to thank Prof. Dr. I. Othman the Director General of the Atomic Energy

Commission of Syria for his encouragement. The authors would like to thanks Dr. M.

Rukiah and Mr. H. Koussa for fruitful discussions

References:

.

.

.

1. Salem I.A., Abdel-Moneum A.A., Shazly A.G. and El-Shibiny N.H Mineralogy and

geochemistry of Gabal El-Ineigi Granite and associated fluorite veins, Central Eastern

Desert, Egypt: application of fluid inclusions to fluorite genesis. J. Afr. Earth Sci., 32,

29-45. (2001)

2. Mernagh, T.P. and Miezitis, Y., A Review of the Geochemical Processes Controlling

the Distribution of Thorium in the Earth’s Crust and Australia’s Thorium Resources.

Geoscience Australia Record 2008/05, 48 p.

3. L. Xinwei, W. Lingqing, J. Xiaodan. Radiometric analysis of Chinese commercial

granites. J. Radioanal. Nucl. Chem., Vol. 267, No.3 (2006) 669–673

4. G. M. Brahmanandhan, S. Selvasekarapandian, J. Malathi, D. Khanna, M. P. Rajan, A.

G. Hegde. Natural radioactivity in the soil samples in and around Kudankulam nuclear

power plant site, J. Radioanal. Nucl. Chem., Vol. 274, No.2 (2007) 361–366

5. XIE Lei, WANG Rucheng, CHEN Xiaoming, QIU Jiansheng & WANG Dezi. Th-rich zircon from

peralka line A-type granite: Mineralogical features and petrological implications.

Chinese Science Bulletin 2005 Vol. 50 No.8 809-817

6. S. Sadasivan, V.K. Shukla, S. Chinnaesakki, S. J. Sartandel. Natural and fallout

radioactivity measurement in Indian soils . J. Radioanal. Nucl. Chem., Vol. 256, No. 3

(2003) 603.607

7. C. M. Garmaccioli, T. V. Segalstad, A uranium- and thorium-rich monazite from a

south-alpine pegmatite at Piona, ItalY. American Mineralogist, Volume 63, pages

757-761, 1978

9

8. Natural Resources Project, Fixed-Wing Low Level Magnetic and Radiometric Surveys.

Technical Report. Vol.1, Ministry of Oil and Mineral Resources. 1990

9. Al-Khirbash, S., El-Anbaawy, M, The Geology of Yemen. Aubadi Publishing Center.

Sana'a, 1999

10. Al- Zouaitary, J. The Radiometric Survey Project for Al Mahfid and ALtawila Areas.

Provisional Report. Geological Survey and Mineral Resources Board. 1999.

11. Browne, E. and Firestone, R.B. Table of Radioisotopes. Editor, J. Wiley and Sons,

Inc. New- York. 1986

12. Abdul-hadi, A. Analysis method for determination of U, Th and K in soils by gamma

ray spectrometry. Valdation methods AECS, Ch. Dep. 2008

13. Knoll, G. Radiation Detection and Measurement. 3rd ed Jhon Wiley &Sons, Inc.

1999

14. Das, H. A., Faanhof, A., and Van der Sloot, H. A. Radioanalysis in Geochemistry,

Elsevier Science. Amsterdam (1989).

15. Durrance, E. M. Radioactivity in Geology. Principles and Applications. Ellis

Horwood Series in Geology. 1986

16. Pavlidou, S. Koroneos, A. Papastefanou, C. Christofides, G. Stoulos, S. Vavelides, M;

Natural Radioactivity of Granites used as building materials in Grecee. Bulletin of the

Geological Society of Greece Vol..XXXVI, April 2004

17. Hassan A.M.1; Abdel-Wahab M.; Nada A.; El-Dine N.W.; Khazbak A. determination

of Uranium and Thorium in Egyptian monazite by Gamma-Ray Spectrometry. Appl.

Radiat. Isot.Vol. 48,No.I,pp 149-152.

18. A. Abbady Radiological hazard and radiogenic heat production in some building

materials in upper Egypt Journal of Radioanalytical and Nuclear Chemistry, Vol.

268, No.2 (2006) 243–246.

19. H. Orabi, A. Al-Shareaif, M. El Galefi Gamma-ray measurements of naturally

occurring radioactive sample from Alkharje City Journal of Radioanalytical and

Nuclear Chemistry, Vol. 269, No.1 (2006) 99–102

*Transfer of copyright statementClick here to download Transfer of copyright statement: Transfer of copyright statement.pdf