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The Measurement of Radon and Radium Concentrations in Well Water in the Afyonkarahisar area of Turkey H. A. Yalim, I. Akkurt, F. B. Ozdemir, R. Unal, A. Sandikcioglu and A. Akkurt Indoor and Built Environment 2007; 16; 77 DOI: 10.1177/1420326X06074731 The online version of this article can be found at: http://ibe.sagepub.com/cgi/content/abstract/16/1/77

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Case Report Indoor Built Environ 2007; 16;1:77–81

Accepted: August 24, 2006

The Measurement of Radon and Radium Concentrations in Well Water in the Afyonkarahisar area of Turkey H. A. Yalima I. Akkurtb F. B. Ozdemira R. Unala A. Sandikcioglua A. Akkurta a

Afyon Kocatepe University, Fen-Edebiyat Fakultesi Fizik Bol, Afyonkarahisar, Turkey Suleyman Demirel University, Fen-Edebiyat Fakultesi Fizik Bol, Isparta, Turkey

b

Key Words Radon · Radium · Well water · Annual effective dose

Abstract Radon, a naturally occurring radioactive noble gas, is the main source of the natural radiation that is received by the population. It derives from the traces of radium in rocks and can diffuse directly or as solution in water to the earth’s surface. Measurements of radium and radon concentration in a total of ten different well waters sampled at about 100 m depth in the Afyonkarahisar area of Turkey have been made. It was found that the concentration ranged from 0.42–28.82 Bq·L1 for radon and from 0.07–7.16 Bq·L1 for radium. A 99% correlation between radon and radium concentrations was found. From these data the average annual effective dose equivalent from radon and radium in the water have been estimated to about 73.8 and 778.96 Sv·y1, respectively.

© 2007 SAGE Publications DOI: 10.1177/1420326X06074731 Accessible online at http://ibe.sagepub.com

Introduction Our environment is constantly irradiated and the origins of the radiation are mainly the decay of radioactive elements and their products in the earth’s crust (U, Th etc.) and cosmic rays from outer space. The earth contained many radioactive isotopes when it was formed four billion years ago. Since then, all the shorter lived isotopes have decayed and only those isotopes with very long half lives (100 million years or more) remain, along with the isotopes formed from the decay of the long-lived isotopes. These naturally-occurring isotopes include uranium and thorium and their decay products, such as radon and radium. The presence of these radionuclides in the ground leads to both external gamma ray exposure and internal exposure from radon and its progeny. Uranium decays through a long chain of radionuclides that includes radon which is a noble gas, not chemically active so it migrates through porous materials like the ground and building materials. Radon may pose a risk when the radioactive gas accumulates in enclosed environments like dwellings and underground cavities. Radon in water arises from the decay of the small amounts of radium present, and also from diffusion through the surrounding soil and rock formations. The

Dr H.A. Yalim Afyon Kocatepe University, Fen-Edebiyat Fakultesi Fizik Bol, Afyonkarahisar, Turkey Downloaded from http://ibe.sagepub.com at Süleyman Demirel Üniversitesi on January 19, 2008 Tel. 902 1339, Fax 902 72228 1235, E-Mail [email protected] © 2007 International Society of the Built Environment. All rights reserved. Not72228 for commercial use or unauthorized distribution.

radon solubility in water is 510 cm3·kg1 at 0 °C and decreases at higher temperatures. Inhalation of short-lived decay product of radon is responsible for half of the effective dose equivalent from all natural sources of radiation [1]. From epidemiological and experimental studies, the carcinogenic effects of radon, such as the increased risk of lung cancer for exposed miners compared to the nonexposed population, have demonstrated potential negative impact of this radionuclide on human health [2]. Radium is also harmful because of its chemical toxicity. In the light of this risk from radon it can be seen how important it is to measure radon concentration, especially in water, as this is the liquid most used for consumption in daily life. Thus, much effort has been made to measure radon in waters from different places in Turkey [3–6] and in other countries around the world [7–13]. In this paper, the radon concentration in drinking water for ten different water supplies in Afyonkarahisar province have been measured and the annual dose rates have been calculated and compared with other values obtained from different places in Turkey.

Materials and Methods Radon and radium concentrations have been determined in the region of Afyonkarahisar, Turkey (Figure 1). The geographic co-ordinates of Afyonkarahisar are:

Ümraniye Bayat 10

8

Emirdag

9

Afyonkarahisar 7 Hocalar

6 5

4 3

Eber G

2

located 260 km south from Ankara (capital city of Turkey), at between 30–32° longitude and 38–40° latitude. The geological structure of the mountains which surround the city are mainly granite and marble types of rocks. It is also in a fault zone, where there have been several periods of seismic activity in the past. The water samples were collected once a week, from ten different public water wells between January–March (samples #1–#6) and June–August (samples #7–#10). All the water for human consumption in this region comes from wells, most of them are more than 100 m deep. Figure 1 shows the location of Afyonkarahisar in Turkey and the places where well water was collected. In Table 1 the places where water samples were collected are named and the period of collection noted. A 500 ml plastic bottle was used to collect water samples after allowing water to flow for some time to ensure a sample of fresh water from each well. The bottles were filled completely, in order not to allow any air in the bottle, and closed tightly. All samples were transported to the Nuclear Physics Laboratory in Afyon Kocatepe University to determine radon and radium concentration. The radon and radium concentrations were measured using the commercially available WG-1001 Vacuum Water Degassing System and AB-5R Radiation Monitor produced by Pylon Electronics. The system was evacuated by pump to a minimum of 584 mm-Hg which is a reduction in the barometric pressure at the altitude of Afyonkarahisar (1000 m). Background radiation of the scintillation cell was measured for 15 min and the outcome was converted to a cpm (count per minute) basis; B. For counting, the scintillation cell was placed in the radiation monitor for approximately 3.5 h after sampling (i.e. when the radon activity in the cell had come to equilibrium). After the decay of fluorescence, the cell is counted for three 5-min intervals. The outcome was

1 Aksehir G. ç

Table 1. The places where and the period when samples were collected in Afyonkarahisar Sample number Place

. Istanbul Eskisehir Dinar Tekirdag Aci G

ç Basi

0 5 km Elazig

Fig. 1. Location of the Afyonkarahisar region on the map of Turkey (inset) with the sampled wells numbered. Areas where other samples have been studied are named on the inset.

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Indoor Built Environ 2007;16:77–81

1 2 3 4 5 6 7 8 9 10

Period

Sultandag˘ ı S ebeke Suyu 1 Sultandag˘ ı S ebeke Suyu 2 Karakuzu Petrol Ofisi Çarıkçılar Petrol Ofisi Gevrek Petrol Ofisi Yakasenek Köyü Keson Kuyular T.M. (Ataköy) Bes˘ ler T.M.Bahçe I˙ çi Kuyu Bes˘ ler T.M. Küçük Çobanlı T.M.

Yalim et al.


18.01.2005–21.03.2005 18.01.2005–28.03.2005 18.01.2005–28.03.2005 31.01.2005–03.03.2005 31.01.2005–13.03.2005 18.01.2005–21.02.2005 23.06.2005–01.08.2005 23.06.2005–01.08.2005 23.06.2005–01.08.2005 23.06.2005–25.07.2005

recorded and converted to a cpm basis; C, and the time of count; Tc recorded. The mean values of those three counts were used to calculate C. Following the operating instructions of the experimental system used for radon and radium determination described in detail by the manufacturer [14] the radon concentrations were determined in water using the following relationship: (C B) A 0.037 F 6.66 D S V Where A is the radon concentration in Bq·L1, C is the gross count rate (cpm), B is the background rate (cpm), F is the cell counting efficiency which normally is 0.745 in the present case, D is the degassing efficiency of 300 A Lucas cell and its value is 0.9, S is the correction for decay of radon from sample time Ts to the count time Tc, V is the sample volume in litres (0.19 L) and 0.037 is the conversion factor between pCi and Bq.

each well are tabulated in Table 2. It can be seen from this table that the radon and radium concentration varies from 3.24 to 22.68 Bq·L1 and 0.55 Bq·L1 to 5.63 Bq·L1, respectively. The highest radon concentration was observed in the samples from well #8 for the date of June, while the lowest radon concentration was in the samples from well #3 for the date of March. The reason for this difference could be a function of the geological structure of the area, the depth of the water well and also differences in the climate between the months of March and June. Others have reported that the geological structure of an area is a predominant factor for high radon concentration [15] and climate condition is also an important factor [16]. When the radon concentrations measured are compared with the allowed maximum contamination level for radon concentration in water (which is 11 Bq·L1), proposed by the US Environmental Protection Agency,

The radon and radium concentrations from ten different wells in the Afyonkarahisar region have been measured. Some of the water samples were collected in the period January to March and the others July to August. Radon and radium levels were found to vary almost fourfold over the measuring period. This is readily seen in the results for sample #6 displayed in Figure 2. It can be seen from this figure that the concentration of radon is higher than that of radium and the variation in radon concentration with the date of sample taken shows more fluctuation than the radium. The average values of all results for

Radon Radium

16 12 8 4 0 18 .0 1. 20 05 28 .0 1. 20 05 07 .0 2. 20 05 17 .0 2. 20 05 27 .0 2. 20 05 09 .0 3. 20 05 19 .0 3. 20 05 29 .0 3. 20 05

Results and Discussion

Concentration (Bq·L)

20

Date

Fig. 2. Variation in radium and radon concentrations over time (sample #6).

Table 2. The average radon concentration and the related annual dose in well water sample from ten different sites in the Afyonkarahisar region. Radon

Radium

Sample number

Concentration (Bq·L1 ± SD)

Annual effective dose (Sv)

Concentration (Bq·L1 ± SD)

Annual effective dose (Sv)

1 2 3 4 5 6 7 8 9 10

4.8 ± 0.7 6.7 ± 1.4 7.6 ± 1.0 4.8 ± 1.3 3.2 ± 0.5 10.2 ± 1.1 21.0 ± 0.8 22.0 ± 2.5 22.7 ± 1.4 20.3 ± 1.3

28.0 ± 8.0 40.3 ± 8.0 45.7 ± 3.0 28.6 ± 6.0 19.4 ± 4.0 60.9 ± 7.0 125.9 ± 15.0 131.1 ± 8.0 136.1±8.0 121.8 ± 5.0

0.9 ± 0.2 1.2 ± 0.2 1.6 ± 0.2 0.8 ± 0.2 0.6 ± 0.1 2.2 ± 0.3 5.2 ± 0.5 4.9 ± 0.8 5.6 ± 0.3 5.0 ± 0.3

235.2 ± 70.0 330.4 ± 70.0 450.8 ± 72.0 229.6 ± 57.0 154.0 ± 25.0 610.4 ± 92.0 1453.2 ± 145.0 1338.4 ± 228.0 1576.4 ± 95.0 1411.2 ± 85.0

Radon and Radium in Well Water in Turkey



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Table 3. The comparison of annual effective dose measured in water obtained from various places in Turkey (see Figure 1)

Location

Reference

Average annual effective dose (Sv) for radon

Afyonkarahisar Elazıg˘ Tekirdag I˙ stanbul Eskisehir

Present work 3 4 5 6

74.0 ± 12.0 14.5 9.3 0.2 1.9

6 y 0.2582x 0.3944 R2 0.9911

Radium concentration (Bq·L)

5

4

3

2

1

0 0

5

10

15

20

25

Radon concentration (Bq·L)

Fig. 3. The relation between the measured radium and radon concentrations.

USEPA [17], it can be seen that some of the samples exceed this limit. On the other hand when the values obtained are compared with the European Commission Recommendations on the protection of the public against exposure to radon in drinking water supplies (2001/928/Euratom) [18], which recommends action levels of 100 Bq·L1 for public water supplies and 1000 Bq·L1 for private water supplies, it can be seen that the levels we measured were below these limits. The annual effective doses have been calculated using the dose conversion factors of 6 Sv·y1·(Bq·L1)1 for radon and 280 Sv·y1·(Bq·L1)1 for radium in water [19,20]; the results are tabulated in Table 2. It can also be seen from this table that the annual effective dose obtained for samples #7, #8, #9 and #10 all exceed the limit recommended by WHO which is 0.1 mSv·y1 for the general public [21]. On the other hand the average value is lower. In the case of radium the highest annual effective dose of 1576 Sv·y1 was obtained and this is obviously higher than the recommended value. In Table 3 the average annual effective dose due to the radon and radium concentration have been compared

80


Average annual effective dose (Sv) for radium 779.0 ± 140.2 55.1 – 0.9 –

with other different sources of well water in Turkey [3–6]. It is clear from this table that the annual dose rate in Afyonkarahisar is higher than some reported values obtained in other places (location indicated in merged part of Figure 1) in Turkey. In order to see whether the origin of the radon was directly due to radium in the surrounding rocks or whether it had been translocated from a more distant source, the correlation between radon and radium levels was investigated. This is displayed in Figure 3, where it can be seen that the linear correlation coefficient between radon and radium concentration was calculated to be 0.99. This suggests that all the radon measured in the water sample resulted from the decay of radium into radon in the immediate (water collecting) geological area.

Conclusions A total of ten water samples from wells which were all located around the Afyonkarahisar region, were examined. The results obtained show that the radon and radium concentration in water are below Euratom limits but it was found that the radon concentration in some well water samples exceeded the recommended WHO value. These results contrast with other measurements from groundwater elsewhere in Turkey. It is obvious from the work that more data on radon concentrations in water will be needed for a deeper study of the influence of geological and hydrogeological and hydrological factors in this area.

Acknowledgement This work is supported by the Science Research Projects Commission of Afyon Kocatepe University with the grant number 041.FENED.06.

Yalim et al.


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