Monitoring the concentration of 238U, 232Th, 40K and 137Cs of soil in Anarak-Khour district, Central Iran

Document Type: Research Paper

Authors

University of Isfahan

Abstract

This study was conducted to determine the radioactivity concentration in soil samples of Anarak-Khour district located at central Iran. 48 soil samples from a depth of 10-15 cm were taken from seven different sites for monitoring. The radioactivity concentration of 238U, 232Th, 137Cs and 40K in soil samples was determined, using a high resolution (HPGe detector, p-type) γ-spectrometry by detectors with 55% and 38.5% relative efficiencies. The results showed that the radioactivity concentration ranged from 9.91 ± 0.11 to 4479.95 ± 0.15 Bq.kg-1 for 238U, from 5.95 ± 0.14 to 389.72 ± 0.10 Bq.kg-1 for 232Th, ≤MDA to 8.89 ± 0.13 Bq.kg-1 for 137Cs and from 123.18 ± 0.27 to 5201.42 ± 0.27 Bq.kg-1 for 40K in soil samples. The calculated internal and external hazard indices were more than 1 in some sites which showed a high dose for this area. These results could be used as a database of this area because it might be used as a nuclear waste site in the future.

Keywords


[Research]

 

Monitoring of the concentration of 238U, 232Th, 40K and 137Cs of soil in Anarak-Khour district, central Iran

E. Ehsanpour1, M. R. Abdi1*, M. Mostajaboddavati2, H. Bagheri3

 

1-Dept. of physics, Faculty of science, University of Isfahan, Iran

2- Dept. of Nuclear Engineering, Faculty of Advance Sciences and Technologies, University of Isfahan, Iran

3-Dept. of Geological Science, Faculty of science, University of Isfahan, Iran

 

*Corresponding author’s E-mail: r.abdi@phys.ui.ac.ir

 (Received: Dec. 09.2014 Accepted: May. 23.2015)

ABSTRACT

This study was conducted to determine the radioactivity concentration in soil samples of Anarak-Khour district located at central Iran. 48 soil samples from a depth of 10-15 cm were taken from seven different sites for monitoring. The radioactivity concentration of 238U, 232Th, 137Cs and 40K in soil samples was determined, using a high resolution (HPGe detector, p-type) γ-spectrometry by detectors with 55% and 38.5% relative efficiencies. The results showed that the radioactivity concentration ranged from 9.91 ± 0.11 to 4479.95 ± 0.15 Bq.kg-1 for 238U, from 5.95 ± 0.14 to 389.72 ± 0.10 Bq.kg-1 for 232Th, ≤MDA to 8.89 ± 0.13 Bq.kg-1 for 137Cs and from 123.18 ± 0.27 to 5201.42 ± 0.27 Bq.kg-1 for 40K in soil samples. The calculated internal and external hazard indices were more than 1 in some sites which showed a high dose for this area. These results could be used as a database of this area because it might be used as a nuclear waste site in the future.

 

Key words:Radioactivity concentration, Gamma spectrometry, Soil, Anarak-khour.


INTRODUCTION

The intersection of Uroomieh-Dokhtar Magmatic Belt (UDMB) and the major Great Kavir-Doruneh fault (GKDF) are two important structural traits in the Anarak-Khour area in central Iran (Fig. 1). This region is in the north-western corner of the Central-Eastern Iranian micro plate. This terrene is an approximately 2300 km2 region of medium relief surrounded by fold and thrust belts within the Alpine-Himalayan orogenic system of western Asia (Bagheri et al., 2006a). In the Anarak-Khour area there are Cu, Ni, Co, As, U, Pb, Zn, Au and Ag deposits which are localized in the same area under similar geological environment along the north-western and western surroundings of Anarak-Khour massif (Badham et al., 1976). The sediments of Meskani and Talmessi in the Anarak mining region which are 7 km apart were mined for copper and nickel until 1960 (Bagheri et al., 2006b). Then mining was discontinued in this area. Recently, exploration activities were continued by the atomic energy organization of Iran due to uranium exploration. The most important active mine in the area is Nakhlak Lead Sediment located in 40 Km east of Anarak. Places that have a greater radioactivity concentration were selected as sample sites. Then the soil samples of this area were collected from 33°15'38.10"N (with 53°37'33.03"E) to 34°12'37.60"N (with 55°18'43.45"E). The studied area is located within the rectangular area and is divided to seven sites as it is shown in Fig. 2.

 

 

Fig 1. Main structural lineaments in Central Iran and location of the study area (modified from Bagheri et al., 2007)

 

 

Fig 2. Sampling sites

 

 

There are a lot of researches which deal with determining the radioactivity concentration throughout Iran (Abdi et al., 2009, 2006a, 2006b, 2008; Pourahmad et al., 2008; Zare et al., 2012). But there is not enough information about Anarak-Khour area which might be used as a site for nuclear waste. The objective of this study was to determine of radioactivity concentration of 238U, 232Th, 137Cs and 40K in Anarak-Khour area and to estimate of possible radiation hazard for the people, which possibly might work in the investigated area in future.

 

MATERIAL AND METHODS

SAMPLING AND PREPARATIONS

48 soil samples from a depth of 10-15 cm were taken from seven different sites. The sample places were chosen in terms of degree-minute-second latitudinal and longitudinal position using a hand-held Global Positioning System (GPS) unit in Table 1. Places that would likely have a greater radioactivity concentration were selected as sample sites so the numbers of samples collected in each site were different. The soil samples were collected from 3 separate holes, with 1 meter width and 10-15 cm depth. The soil samples were dried by spreading them on polythene layers at room temperature for 2 weeks under a controlled environment to avoid local dust pollution. Then, the soil samples were oven dried at 110° C for 24 hours. They were passed through a 50 mesh sieve. 950 g of each sample was transferred to Marinelli-beakear. Then, the Marinelli-beakers were sealed and kept for at least 5 weeks. During this time, the daughter of radon achieved to equilibrium with 226Ra and the samples were ready to be analyzed by gamma spectroscopy (Abdi et al., 2008, 2009).

 

GAMMA-RAY DETECTION SYSTEM

The activity of 238U (226Ra), 232Th, 40K and 137Cs in the samples were measured using two P-type coaxial HPGe detectors. The relative efficiency of the detectors was 55% with energy resolution of 1.98 keV and 38.5% with energy resolution of 1.8keV at 1.33 MeV of 60Co. The detectors were kept in a vertical position and shielded by 10 cm thickness lead wall, 2 mm cadmium and 3 mm copper to reduce background radiation (Debertin et al., 1988). Spectrum acquisition was done using the computer software MAESTRO with a multichannel analyzer (4096-channel) and spectrum analysis was done by the OMNIGAM software. In order to measure the activity of a sample, it is necessary to know the detection efficiency of the system by standard sources which have physical dimensions, chemical composition and density similar to the samples. If standard Marinelli beakers are used for standards and samples with similar geometry, the deviation can be reduced almost to zero (Mostajaboddavati et al., 2006).

The reference material IAP-mixed gamma soil standard sources (Institute of Atomic Energy POLATOM, Radioisotope Center) containing 241Am (0.49 ± 0.004 Bq.kg-1), 137Cs (0.09 ± 0.001 Bq.kg-1) and 152Eu (0.11 ± 0.001 Bq.kg-1) were used to obtain efficiency curve. The absolute photopeak efficiencies and activities were determined using following equation (Abbas, 2001):

(1)

(2)

Where N, t, m, p and ɛ (E) are net area counts, time, intensity, sample weight and absolute photo peak efficiency at specific energy, respectively (Faghihian et al., 2012). The specific activity of 238U and 226Ra was determined by gamma-ray lines of 214Bi at 609.3, 1120.3 and 1764.5 keV and 214Pb at 295 and 351 keV, while the specific activity of 232Th was evaluated by gamma-ray lines of 228Ac at 338.4, 911.1 and 968.9 keV. The specific activity of 40K and 137Cs were measured by their 1460.8 and 661.6 keV gamma-ray lines (Abbas, 2001).

The absorbed dose rates (D) are calculated according to UNSCEAR (2000) due to gamma radiation in air, 1m above the ground level for 238U, 232Th and 40K radio nuclides as following:

 

The annual effective outdoor dose rate in units of mSv.year−1 is calculated using the following formula (Farai et al., 2005):

 

The radium equivalent activity is a sum of the studied natural radio nuclides and is based on the hypothesis that 370 Bq.L-1 of 226Ra, 259    Bq.L -1 of 232Th, and 4810 Bq.L-1 of 40K produce the same gamma radiation dose rate (Farai et al., 2005). The maximum value of Raeq must be less than 370 Bq.L-1 for safe use (Abbady, 2004). It is defined as follows:

 

 

Where ARa, ATh and AK are the radioactivity concentrations of 226Ra, 232Th and 40K, respectively.

A hazard index called the external hazard index Hex is defined as follows (UNSCEAR, 2000):

 

 

In addition to the external hazard index, radon and its short-lived progeny are hazardous to the respiratory organs. The internal exposure to radon and its daughter progenies is evaluated by the internal hazard index Hin, which is given in the following equation (UNSCEAR, 2000):

 

 

 

Table 1. Sampling spots information.

No. samples

Longitude

Latitude

altitude

Site No. 1

 

 

 

1

33°15'38.10"

53°37'33.03"

1286

2

33°16'44.97"

53°35'18.33"

1335

3

33°17'22.80"

53°34'32.30"

1370

4

33°18'10.26"

53°33'34.40"

1413

5

33°18'52.57"

53°32'46.18"

1466

6

33°19'56.50"

53°27'55.61"

1427

7

33°19'53.50"

53°27'57.78"

1421

8

33°19'55.00"

53°28'3.65"

1419

9

33°21'57.36"

53°27'46.70"

1418

10

33°22'5.90"

53°27'47.20"

1424

11

33°22'46.52"

53°27'47.90"

1465

12

33°23'28.00"

53°27'49.30"

1512

13

33°23'28.20"

53°27'51.80"

1523

14

33°23'20.25"

53°27'48.90"

1506

15

33°23'20.25"

53°27'48.90"

1520

Site No. 2

 

 

 

16

33°20'48.00"

53°42'24.63"

1648

17

33°22'8.52"

53°42'6.18"

1564

18

33°23'8.20"

53°41'14.70"

1450

19

33°25'5.91"

53°42'4.67"

1329

20

33°27'26.80"

53°44'42.92"

1197

21

33°29'0.77"

53°48'3.83"

1137

22

33°29'0.12"

53°48'6.19"

1134

23

33°30'26.60"

53°52'2.69"

1014

24

33°33'1.05"

53°52'23.30"

935

25

33°33'26.80"

53°50'49.72"

1011

26

33°33'27.78"

53°50'49.09"

1006

Site No. 3

 

 

 

27

33°26'23.43"

54°11'59.17"

1189

28

33°24'47.62"

54°12'40.30"

1146

29

33°24'47.50"

54°12'40.28"

1146

30

33°24'12.33"

54°13'31.96"

1196

31

33°23'58.43"

54°14'18.98"

1263

32

33°23'58.17"

54°14'18.91"

1253

Site No. 4

 

 

 

33

33°55'38.50"

54°20'49.79"

1210

34

34° 2'39.43"

54°24'15.00"

960

35

34° 1'53.48"

54°26'20.26"

985

Site No. 5

 

 

 

37

33°43'5.91"

55° 3'22.80"

960

38

33°36'23.62"

54°56'20.96"

906

39

33°29'33.80"

54°55'18.45"

1081

Site No. 6

 

 

 

36

33°56'41.90"

55° 1'27.22"

948

40

33°53'2.82"

55° 6'50.44"

796

41

33°53'2.82"

55° 6'50.45"

796

42

34° 1'44.81"

55° 6'13.56"

984

Site No. 7

 

 

 

43

34°12'37.60"

55°18'43.45"

727

44

34°12'35.10"

55°18'42.97"

727

45

34°12'25.05"

55°19'2.25"

729

46

34°12'24.90"

55°19'1.45"

737

47

34°12'21.00"

55°18'58.48"

722

48

34°12'24.90"

55°19'1.45"

737

 


 

 

 

RESULTS AND DISCUSSION

In this study, duplication of the analysis samples, the blank samples and a standard mixed source containing 241Am, 109Cd, 57Co, 133Ba, 137Cs and 60Co (Institute of Atomic Energy POLATOM, Radioisotope Center) which have a geometry identical to those of the soil samples have been used for quality control procedures. The results of the standard mixed source are shown in Table 2. Also, a routinely daily checking such as energy calibration of the gamma spectroscopy system had been applied. Each sample was analyzed two times and the mean value of them were calculated and reported here, the recovery in many elements was about 98%.

 

 

Table 2. Standard mixed source data.

Radionuclide

Energy (keV) (Intensity %)

Activity (kBq)

Efficiency (%)

Am-241

59.54 keV (35.9%)

3.5 ± 0.03

1.0 ± 0.01

Ba-133

276.39 keV (7.16%)

302.85 keV (18.33%)

356.01 keV (62.05%)

383.84 keV (8.94%)

3.4 ± 0.04

3.3 ± 0.05

3.2 ± 0.04

2.8 ± 0.03

2.8 ± 0.04

Cs-137

661.66 keV (85.1%)

3.1 ± 0.08

1.7 ± 0.05

Cd-109

88.03 keV (3.61%)

3.8 ± 0.12

2.9 ± 0.1

Co-57

122.06 keV (85.6%)

136.47 keV (10.68%)

3.7 ± 0.04

3.5 ± 0.04

3.7 ± 0.04

Co-60

1173.24 keV (99.97%)

1332.5 keV (99.99%)

3.5 ± 0.04

1.1 ± 0.01

1.0 ± 0.01

 

 

The radioactivity concentration of 238U (226Ra), 232Th, 40K, and 137Cs in the soil samples collected from different parts of the studied area are given in Table 3. The radioactivity concentration ranged from 9.91 to 4479.95 Bq.kg-1 for 238U (226Ra); from 5.95 to 389.72 Bq/kg for 232Th; from 123.18 to 5201.42 Bq.kg-1 for 40K and from -1 for 137Cs. A part of Irakan Zone (Site No.7) has the high radioactivity concentration of 238U and 232Th which might be attributed to the geological structure of the region (Ayoubi et al., 2012). Also, the maximum radioactivity concentration of 40K is found in sample No. 48 (Irakan Zone). The radioactivity concentration of 137Cs in site No. 7 (Irakan Zone) is less than minimum detection analysis (MDA) which is maybe related to the altitude of this area. Less than MDA radioactivity concentration of 137Cs in site No.7 is not related to the erosion (Ayoubi et al., 2012; Bagheri et al., 2013). However, because of that this site has the almost the lowest altitude as compared to other sites, accumulation of rainwater in this area caused the 137Cs deposited in the depth of 10-15 cm which our samples were being collected. Fig. 3 shows the distribution of 238U, 232Th, 137Cs and 40K radioactivity concentrations of soil samples in seven sites.  To evaluate the studied area the radioactivity concentration of 238U (226Ra), 232Th, 40K, and 137Cs were compared with those reported from the other parts of Iran and then compared with those that were reported from other countries. By comparing our results with other parts of Iran, it is clear that the average radioactivity concentration of 238U (226Ra) and 40K in the studied area is relatively high. The radioactivity concentration of 232Th and 137Cs reported in the north of Iran is higher than the studied area. For example, average radioactivity concentration of 137Cs is higher in Guilan (Sadremomtaz et al., 2010).

It is maybe due to the fact that the north of Iran is an agricultural area in which fertilizers that contain of Th element (Rezaee, 2009). Also our results have been compared with results which were reported in other parts of the center of Iran by Ayoubi, Afshar and Rahimi. It shows the radioactivity concentration of 137Cs in this area is less than other parts of center of Iran (Afshar et al., 2010; Ayoubit et al., 2012; Rahimi et al., 2013). The average radioactivity concentration of 238U (226Ra) of our samples is less than those reported from Malaysia but more than other countries for example China, Egypt, Greece, Kuwait and South Carolina (Yanga et al., 2005; Morsy et al., 2012; Travidon et al., 1996; Saad et al., 2002; Nasirian et al., 2008; Khan et al., 2011; Powell et al., 2007; Kam et al., 2007, 2010 and UNSCEAR, 2000). The radioactivity concentration of 238U (226Ra) of our samples is more than acceptable value (35 Bq.kg-1).

The radioactivity concentration of 232Th of our samples is less than those reported from Malaysia and is approximately equal to acceptable value of 35 Bq.kg-1. The radioactivity concentration of 40K of our samples is approximately equal to those reported from other countries (Table 4). The acceptable value of 40K is 370 Bq.kg-1 which shows that our data are more than the acceptable amount. The absorbed dose rates (D), annual effective outdoor dose rate, radium equivalent activity (Raeq), Hex and Hin of our samples are calculated and their results are shown in the Table 5. The calculated total gamma dose rate varied from 13.41 to 2284.27 ­nGy.h-1 among soil samples due to primordial radio nuclides.

In average, the absorbed dose rate (nGy.h-1) of seven sites is reported in Table 5. The average total gamma dose rate is more than the worldwide average of 55 nGy.h-1 in some sites (Abdi et al., 2009). The annual effective dose obtained for the seven sites ranged from 0.02 mSv in site No.2 to 2.81 mSv in site No.7 for the background area.

If the value of internal or external radiation hazard index is found to be less than unity, then there is no potential internal or external radiation hazard. Both the external radiation hazard index (Hex) and the internal radiation hazard index (Hin) in some sites are more than unit. This indicates that the soils of Anarak-khour area are not free from the radiation hazards.

 

 

 

Fig 3. Distribution of radioactivity concentrations of 238U, 232Th, 40K and 137Cs in soil samples

 

Table 4. Comparison of radioactivity of soils with other areas of the world.

Position

238U (Bq.Kg-1)

232Th (Bq.Kg-1)

137Cs (Bq.Kg-1)

40K (Bq.Kg-1)

Our samples

263.80

37.45

1.88

646.78

Iran

28

22

-

640

China

112

71.5

-

672

Egypt

6.57

8.46

-

1363

Greece

214

43

-

1130

Kuwait

36

6

-

227

Malaysia

860.57

637.61

-

-

Pakistan

-

43.27

-

418.27

South Carolina

37.8

45.3

-

609.3

Turkey

-

30

8.02

431.43

Turkey

-

110.4

19.39

1273

Acceptable value

35

35

-

370

 

Table 3. Radioactivity concentration of 238U, 232Th, 137Cs and 40K in soil samples.

No. samples

238U(Bq.kg-1)

232Th(Bq.kg-1)

137Cs(Bq.kg-1)

40K(Bq.kg-1)

1

22.53 ± 0.12

21.29 ± 0.08

0.77 ± 0.09

420.55 ± 0.18

2

28.84 ± 0.12

27.2 ± 0.09

1.72 ± 0.09

509.89 ± 0.18

3

21.13 ± 0.08

21.25 ± 0.10

1.33 ± 0.10

399.25 ± 0.18

4

20.79 ± 0.12

16.44 ± 0.08

1.04 ± 0.09

312.94 ± 0.18

5

19.03 ± 0.12

13.71 ± 0.09

1.27 ± 0.09

238.95 ± 0.18

6

422.75 ± 0.13

38.71 ± 0.10

0.79 ± 0.09

1118.57 ± 0.18

7

508.42 ± 0.13

48.35 ± 0.09

1.14 ± 0.10

1474.00 ± 0.18

8

699.00 ± 0.13

27.92 ± 0.11

≤MDA

737.64 ± 0.18

9

22.12 ± 0.12

23.53 ± 0.11

≤MDA

527.87 ± 0.27

10

18.91 ± 0.10

23.74 ± 0.12

≤MDA

459.38 ± 0.27

11

37.52 ± 0.12

11.54 ± 0.12

1.45 ± 0.13

192.68 ± 0.27

12

85.73±0.13

44.80 ± 0.13

2.36 ± 0.13

1587.14 ± 0.27

13

247.54 ± 0.13

34.78 ± 0.13

2.13 ± 0.13

1155.14 ± 0.27

14

550.73 ± 0.13

40.66 ± 0.14

≤MDA

1597.19 ± 0.27

15

724.69 ± 0.13

37.88 ± 0.12

≤MDA

1115.60 ± 0.27

16

13.70 ± 0.13

17.83 ± 0.11

3.69 ± 0.13

443.09 ± 0.27

17

20.45 ± 0.12

23.08 ± 0.11

≤MDA

528.13 ± 0.27

18

16.47 ± 0.12

22.13 ± 0.11

1.50 ± 0.13

490.69 ± 0.27

19

9.91 ± 0.11

5.95 ± 0.14

2.03 ± 0.13

123.18 ± 0.27

20

23.49 ± 0.13

27.49 ± 0.11

4.05 ± 0.13

498.64 ± 0.27

21

33.31 ± 0.11

21.19 ± 0.09

6.79 ± 0.09

571.74 ± 0.18

22

229.04 ± 0.12

11.83 ± 0.10

≤MDA

159.82 ± 0.18

23

21.15 ± 0.11

18.90 ± 0.09

1.94 ± 0.09

301.04 ± 0.18

24

22.09 ± 0.12

15.01 ± 0.08

1.60 ± 0.09

311.50 ± 0.18

25

62.27 ± 0.12

15.66 ± 0.11

≤MDA

235.31 ± 0.18

26

34.93 ± 0.12

13.49 ± 0.12

≤MDA

199.36 ± 0.18

27

66.09 ± 0.13

19.67 ± 0.09

4.43 ± 0.09

423.76 ± 0.18

28

28.00 ± 0.13

29.44 ± 0.09

2.40 ± 0.09

821.25 ± 0.18

29

30.81 ± 0.11

31.66 ± 0.08

5.54 ± 0.09

804.61 ± 0.18

30

49.49 ± 0.10

17.55 ± 0.10

0.76 ± 0.11

493.80 ± 0.18

31

42.40 ± 0.11

44.36 ± 0.08

7.07 ± 0.09

1175.25 ± 0.18

32

513.27 ± 0.12

71.27 ± 0.09

≤MDA

246.86 ± 0.18

33

24.21 ± 0.13

13.48 ± 0.09

3.41 ± 0.09

292.43 ± 0.18

34

22.87 ± 0.11

18.81 ± 0.09

5.81 ± 0.09

421.41 ± 0.18

35

21.31 ± 0.11

13.49 ± 0.09

2.30 ± 0.09

253.52 ± 0.18

36

22.26 ± 0.12

10.24 ± 0.09

2.61 ± 0.09

237.10 ± 0.18

37

24.17 ± 0.11

21.25 ± 0.09

4.47 ± 0.09

488.63 ± 0.18

38

18.23 ± 0.11

17.21 ± 0.09

2.82 ± 0.09

329.72 ± 0.18

39

17.59 ± 0.09

26.02 ± 0.09

2.00 ± 0.09

434.46 ± 0.18

40

36.34 ± 0.13

27.42 ± 0.13

≤MDA

429.45 ± 0.27

41

34.90 ± 0.12

11.92 ±0 .13

2.41 ± 0.13

299.76 ± 0.27

42

24.25 ± 0.13

25.69 ± 0.10

8.89 ± 0.13

610.60 ± 0.27

43

228.98 ± 0.14

17.96 ± 0.18

≤MDA

498.48 ± 0.27

44

23.70 ± 0.12

14.93 ± 0.12

≤MDA

487.32 ± 0.27

45

338.25 ± 0.13

16.77 ± 0.13

≤MDA

473.00 ± 0.27

46

4479.95 ± 0.15

315.6 1± 0.17

≤MDA

444.64 ± 0.27

47

31.59 ± 0.12

19.05 ± 0.14

≤MDA

469.10 ± 0.27

48

2667.23 ± 0.18

389.7 2± 0.10

≤MDA

5201.42 ± 0.27

Max

4479.95

389.72

8.89

5201.42

Average

263.8

37.5

1.9

646.8

STD

746.3

67.9

2.2

763.0

CV (%)

282.9

181.3

115.0

118.0

 

 

 

Table 5. Calculated values of absorbed dose rate and annual effective dose, radium equivalent activity, external and internal radiation hazard.

 

Absorbed dose rate (nGy.h-1)

Annual effective dose (mSv.year-1)

Radium equivalent activity (Bq.Kg-1)

External radiation hazard index (Hex)

Internal radiation hazard index (Hin)

Sit No.1

         

Min

27.27

0.03

55.36

0.15

0.21

Max

404.85

0.50

856.95

2.34

4.30

Average

156.45

0.19

325.10

0.89

1.51

Site No.2

         

Min

13.41

0.02

27.04

0.08

0.10

Max

119.83

0.15

257.14

0.70

1.32

Average

45.96

0.06

93.87

0.26

0.38

Site No.3

         

Min

54.35

0.07

109.15

0.30

0.44

Max

291.68

0.36

632.47

1.72

3.10

Average

105.92

0.13

218.93

0.61

0.93

Site No.4

         

Min

28.79

0.04

58.35

0.16

0.22

Max

39.82

0.05

79.27

0.22

0.28

Average

33.45

0.04

67.19

0.19

0.25

Site No.5

         

Min

32.86

0.04

65.92

0.19

0.23

Max

44.74

0.06

88.76

0.25

0.31

Average

40.00

0.05

79.96

0.22

0.28

Site No.6

         

Min

26.53

0.03

53.50

0.15

0.21

Max

52.62

0.06

105.61

0.29

0.39

Average

41.73

0.05

83.94

0.24

0.31

Site No.7

         

Min

40.54

0.05

79.16

0.22

0.29

Max

2284.27

2.81

4962.40

13.43

25.53

Average

731.02

0.90

1567.79

4.27

7.76

           

Min

13.41

0.02

27.04

0.08

0.10

Max

2284.27

2.81

4962.40

13.43

25.53

Average

172.11

0.21

362.64

0.99

1.71

 


CONCLUSION

The mean radioactivity concentrations of 238U, 232Th, 40K and 137Cs in 48 investigated soil samples determined in the present study were within the acceptable limits. But the radioactivity concentration of 238U, 232Th in site No.7 (Irakan Zone) is higher than the other results. This can be attributed to the geological structure of the region. Preliminary values for the radium equivalent (Raeq) and radiation hazard index were determined for each of the samples. The average radium equivalent activity was below the defined limit of 370 Bq.kg-1. The external hazard indices were found to be more than 1, indicating a high dose for some areas. These indicate that the areas monitored cannot be regarded as the one having normal levels of natural background radiation. This study can be followed by analyzing drinking water and plants of the studied area. Moreover, because there are a lot of people who physically are impaired, the birth rate of children with defect should be compared with the radionuclide concentrations in soils, waters and plants in every few years. Our results will contribute for data base of this area in future. Then it is necessary that after operating the disposal site of nuclear waste all environment samples of the studied area should be performed every year and compared with our results.

 

ACKNOWLEDGEMENT

The authors would like to thank the staff of central laboratory of University of Isfahan for their assistance. Also, the authors wish to thank Dr. Rezaee for her help and her valuable guidance.

Abbady, A. G. E. (2004) Estimation of radiation hazard indices from sedimentary rocks in Upper Egypt. Appl. Radiat. Isot, 60, 111–114.

Abbas, M. I. (2001) HPGe detector photopeak efficiency calculation including self-absorption and coincidence corrections for Marinelli beaker sources using compact analytical expressions. Appl. Radiat. Isot, 54, 761-768.

Abdi, M. R., Faghihian, H., Kamali, M., Mostajaboddavati, M., Hassanzadeh, S. (2006b) Distribution of natural radionuclides on coasts of Bushehr, Persian Gulf, Iran. Iranian Journal of Science & Technology, 30, 259-269.

Abdi, M. R., Faghihian, H., Mostajaboddavati, M., Hassanzadeh, S., Kamali, M. (2006a) Distribution of natural radionuclides and hot points in coasts of Hormozgan, Persian Gulf, Iran. J. Radioanal Nucl Chem, 270, 319–324.

Abdi, M. R., Hassanzadeh, S., Kamali, M., Raji, H. R. (2009) 238U, 232Th, 40K and 137Cs activity concentrations along the southern coast of the Caspian Sea, Iran. Mar. Pollut. Bull., 58, 658–662.

Abdi, M. R., Kamali, M., Vaezifar, S. (2008) Distribution of radioactive pollution of 238U, 232Th, 40K and 137Cs in northwestern coasts of Persian Gulf, Iran. Mar. Pollut. Bull., 56, 751–757.

Afshar, F.A., Ayoubi, Sh., Jalalin,A. (2010) Soil redistribution rate and its relationship with soil organic carbon and total nitrogen using 137Cs technique in a cultivated complex hillslope in western Iran. J. Environmental Radioactivity.101:606-614.

Ayoubi, Sh., Ahmadi, M., Abdi, M. R., Abbaszadeh Afshar, F. (2012) Relationships of 137Cs inventory with magnetic measures of calcareous soils of hilly region in Iran. J. Environ. Radioact. 112, 45-51.

Badham J. P. N. (1976) Orogenesis and metallogenesis with reference to the silver-nickel, cobalt arsenide ore association. Geol. Soc. Canada Special Paper, 14, 559-571.

Bagheri I., Naghdi R, Jalali A.M. (2013) Evaluation of factors affecting soil erosion along skid trails (Case study; Shafarood Forest, Northern Iran). Caspian J. Env. Sci., 11 (2):151-160.

Bagheri, H., Moore, F. (2006a) Alderton D. H. M., Cu-Ni-Co-As (U) mineralization in the Anarak area of Central Iran. J. Asian Earth Sci. 29, 651-665.

Bagheri, H., Moore, F., Shamsipour, R. (2006b) Tectonic Reactivation and polyphase mineralization in the Anarak area, Central Iran, J. Geol. Soc. Iran, 1, 61-72.

Debertin, K., Helmer, R. G. (1988) Gamma and X-ray spectrometry with semiconductor detectors (Elsevier, Amsterdam).

Faghihian, H., Rahi, D., Mostajaboddavati, M. (2012) Study of natural radionuclides in Karun river region. J. Radioanal Nucl Chem, 292, 711-717.

Farai, I. P., Ademola, J. A. (2005) Radium equivalent activity concentrations in concrete building blocks in eight cities in Southwestern Nigeria. J. Environ. Radioact. 79, 119–125.

Hassanzadeh, S., Kamali, M., Raji. H. R. (2009) 238U, 232Th, 40K and 137Cs activity concentrations along the southern coast of the Caspian Sea, Iran. Mar. Pollut. Bull., 58, 658–662.

Kam, E., Bozkurt, A. (2007) Environmental radioactivity measurements in Kastamonu region of northern Turkey. Appl. Radiat. Isot, 65, 440-444.

Kam, E., Bozkurt, A., Ilgar, R. (2010) a study of background radioactivity level for Canakkale, Turkey. Environ. Monit. Assess. 168, 685-690.

Khan, H. M., Ismail, M., Khan, K., Akhter, P. (2011) Measurement of Radionuclides and Gamma-Ray Dose Rate in Soil and Transfer of Radionuclides from Soil to Vegetation, Vegetable of Some Northern Area of Pakistan Using γ-Ray Spectrometry. Water Air Soil Pollut. 219, 129-142.

Morsy, Z., El-Wahab, M. A., El-Faramawy, N. (2012) Determination of natural radioactive elements in Abo Zaabal, Egypt by means of gamma spectroscopy. Ann Nucl Energy, 44, 8-11.

Mostajaboddavati, M., Hassanzadeh, S., Faghihian, H., Abdi, M. R., Kamali, M. (2006) Efficiency calibration and measurement of self-absorption correction for environmental gamma spectroscopy of soil samples using Marinelli beaker. J. Radioanal Nucl Chem, 268, 539-544.

Nasirian, M., Bahari, I., Abdullah, P. (2008) Assessment of natural radioactivity in water and sediment from Amang (Tin Tailling) processing. The Malaysian Journal of Analytical Sciences, 12, 150-159.

Pourahmad, J., Motallebi, A., Asgharizadeh, F., Eskandari, G. R., Shafaghi, B. (2008) Radioactivity Concentrations in Sediments on the Coast of the Iranian Province of Khuzestan in the Northern Persian Gulf. Environ. Toxicol. 23, 583-590.

Powell, B., Hughes, L., Soreefan,A., Falta, D., Wall, M., DeVol, T. (2007) Elevated concentrations of primordial radionuclides in sediments from the Reedy River and surrounding creeks in Simpsonville, South Carolina. J. Environ. Radioact. 94, 121-128.

Rezaee, Kh. (2009) 232Th and 238U radioactive contaminations of sediments along the South China Sea of east coast Peninsular Malaysia by INAA, International Nuclear Conference 2009 & Exhibition.

Saad,H. R., Al-Azmi, D. (2002) Radioactivity concentrations in sediments and their correlation to the coastal structure in Kuwait. Appl. Radiat. Isot, 56, 991-997.

Sadremomtaz A., Moghaddam M.V., Khoshbinfar S, Moghaddasi A. (2010) a comparative study of field gamma-ray spectrometry by NaI (Tl) and HPGe detectors in the South Caspian Region. Caspian J. Env. Sci., 8 (2):203-210.

Travidon, G., Flouro,H., Angelopoulos, A., Sakelliou, L. (1996) Envioronmental study of the radioactivity of the Spas in the Island of Ikaria, Greece. Radiat. Prot. Dosim., 63, 63-67.

UNSCEAR, Sources and Effects of Ionizing Radiation (Report to the General Assembly) (United Nations, New York, 2000).

Yanga, Y. X., WuX.M., JiangZ.Y., Wang,W.X., Lu,J.G., Lin,J., Wang,L.M., Hsia,Y.F. (2005) Radioactivity concentrations in soils of the Xiazhuang granite area, China. Appl. Radiat. Isot, 63, 255-259.

Zare, M. R., Mostajaboddavati, M., Kamali, M., Abdi, M. R., Mortazavi, M. S. (2012) 235U, 238U, 232Th, 40K and 137Cs activity concentrations in marine sediments along the northern coast of Oman Sea using high-resolution gamma-ray spectrometry. Mar. Pollut. Bull., 64, 1956–1961.

 

 

 

Abbady, A. G. E. (2004) Estimation of radiation hazard indices from sedimentary rocks in Upper Egypt. Appl. Radiat. Isot, 60, 111–114.

Abbas, M. I. (2001) HPGe detector photopeak efficiency calculation including self-absorption and coincidence corrections for Marinelli beaker sources using compact analytical expressions. Appl. Radiat. Isot, 54, 761-768.

Abdi, M. R., Faghihian, H., Kamali, M., Mostajaboddavati, M., Hassanzadeh, S. (2006b) Distribution of natural radionuclides on coasts of Bushehr, Persian Gulf, Iran. Iranian Journal of Science & Technology, 30, 259-269.

Abdi, M. R., Faghihian, H., Mostajaboddavati, M., Hassanzadeh, S., Kamali, M. (2006a) Distribution of natural radionuclides and hot points in coasts of Hormozgan, Persian Gulf, Iran. J. Radioanal Nucl Chem, 270, 319–324.

Abdi, M. R., Hassanzadeh, S., Kamali, M., Raji, H. R. (2009) 238U, 232Th, 40K and 137Cs activity concentrations along the southern coast of the Caspian Sea, Iran. Mar. Pollut. Bull., 58, 658–662.

Abdi, M. R., Kamali, M., Vaezifar, S. (2008) Distribution of radioactive pollution of 238U, 232Th, 40K and 137Cs in northwestern coasts of Persian Gulf, Iran. Mar. Pollut. Bull., 56, 751–757.

Afshar, F.A., Ayoubi, Sh., Jalalin,A. (2010) Soil redistribution rate and its relationship with soil organic carbon and total nitrogen using 137Cs technique in a cultivated complex hillslope in western Iran. J. Environmental Radioactivity.101:606-614.

Ayoubi, Sh., Ahmadi, M., Abdi, M. R., Abbaszadeh Afshar, F. (2012) Relationships of 137Cs inventory with magnetic measures of calcareous soils of hilly region in Iran. J. Environ. Radioact. 112, 45-51.

Badham J. P. N. (1976) Orogenesis and metallogenesis with reference to the silver-nickel, cobalt arsenide ore association. Geol. Soc. Canada Special Paper, 14, 559-571.

Bagheri I., Naghdi R, Jalali A.M. (2013) Evaluation of factors affecting soil erosion along skid trails (Case study; Shafarood Forest, Northern Iran). Caspian J. Env. Sci., 11 (2):151-160.

Bagheri, H., Moore, F. (2006a) Alderton D. H. M., Cu-Ni-Co-As (U) mineralization in the Anarak area of Central Iran. J. Asian Earth Sci. 29, 651-665.

Bagheri, H., Moore, F., Shamsipour, R. (2006b) Tectonic Reactivation and polyphase mineralization in the Anarak area, Central Iran, J. Geol. Soc. Iran, 1, 61-72.

Debertin, K., Helmer, R. G. (1988) Gamma and X-ray spectrometry with semiconductor detectors (Elsevier, Amsterdam).

Faghihian, H., Rahi, D., Mostajaboddavati, M. (2012) Study of natural radionuclides in Karun river region. J. Radioanal Nucl Chem, 292, 711-717.

Farai, I. P., Ademola, J. A. (2005) Radium equivalent activity concentrations in concrete building blocks in eight cities in Southwestern Nigeria. J. Environ. Radioact. 79, 119–125.

Hassanzadeh, S., Kamali, M., Raji. H. R. (2009) 238U, 232Th, 40K and 137Cs activity concentrations along the southern coast of the Caspian Sea, Iran. Mar. Pollut. Bull., 58, 658–662.

Kam, E., Bozkurt, A. (2007) Environmental radioactivity measurements in Kastamonu region of northern Turkey. Appl. Radiat. Isot, 65, 440-444.

Kam, E., Bozkurt, A., Ilgar, R. (2010) a study of background radioactivity level for Canakkale, Turkey. Environ. Monit. Assess. 168, 685-690.

Khan, H. M., Ismail, M., Khan, K., Akhter, P. (2011) Measurement of Radionuclides and Gamma-Ray Dose Rate in Soil and Transfer of Radionuclides from Soil to Vegetation, Vegetable of Some Northern Area of Pakistan Using γ-Ray Spectrometry. Water Air Soil Pollut. 219, 129-142.

Morsy, Z., El-Wahab, M. A., El-Faramawy, N. (2012) Determination of natural radioactive elements in Abo Zaabal, Egypt by means of gamma spectroscopy. Ann Nucl Energy, 44, 8-11.

Mostajaboddavati, M., Hassanzadeh, S., Faghihian, H., Abdi, M. R., Kamali, M. (2006) Efficiency calibration and measurement of self-absorption correction for environmental gamma spectroscopy of soil samples using Marinelli beaker. J. Radioanal Nucl Chem, 268, 539-544.

Nasirian, M., Bahari, I., Abdullah, P. (2008) Assessment of natural radioactivity in water and sediment from Amang (Tin Tailling) processing. The Malaysian Journal of Analytical Sciences, 12, 150-159.

Pourahmad, J., Motallebi, A., Asgharizadeh, F., Eskandari, G. R., Shafaghi, B. (2008) Radioactivity Concentrations in Sediments on the Coast of the Iranian Province of Khuzestan in the Northern Persian Gulf. Environ. Toxicol. 23, 583-590.

Powell, B., Hughes, L., Soreefan,A., Falta, D., Wall, M., DeVol, T. (2007) Elevated concentrations of primordial radionuclides in sediments from the Reedy River and surrounding creeks in Simpsonville, South Carolina. J. Environ. Radioact. 94, 121-128.

Rezaee, Kh. (2009) 232Th and 238U radioactive contaminations of sediments along the South China Sea of east coast Peninsular Malaysia by INAA, International Nuclear Conference 2009 & Exhibition.

Saad,H. R., Al-Azmi, D. (2002) Radioactivity concentrations in sediments and their correlation to the coastal structure in Kuwait. Appl. Radiat. Isot, 56, 991-997.

Sadremomtaz A., Moghaddam M.V., Khoshbinfar S, Moghaddasi A. (2010) a comparative study of field gamma-ray spectrometry by NaI (Tl) and HPGe detectors in the South Caspian Region. Caspian J. Env. Sci., 8 (2):203-210.

Travidon, G., Flouro,H., Angelopoulos, A., Sakelliou, L. (1996) Envioronmental study of the radioactivity of the Spas in the Island of Ikaria, Greece. Radiat. Prot. Dosim., 63, 63-67.

UNSCEAR, Sources and Effects of Ionizing Radiation (Report to the General Assembly) (United Nations, New York, 2000).

Yanga, Y. X., WuX.M., JiangZ.Y., Wang,W.X., Lu,J.G., Lin,J., Wang,L.M., Hsia,Y.F. (2005) Radioactivity concentrations in soils of the Xiazhuang granite area, China. Appl. Radiat. Isot, 63, 255-259.

Zare, M. R., Mostajaboddavati, M., Kamali, M., Abdi, M. R., Mortazavi, M. S. (2012) 235U, 238U, 232Th, 40K and 137Cs activity concentrations in marine sediments along the northern coast of Oman Sea using high-resolution gamma-ray spectrometry. Mar. Pollut. Bull., 64, 1956–1961.