This article was downloaded by: [New York University] On: 18 May 2015, At: 13:36 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Isotopes in Environmental and Health Studies Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gieh20
Natural radioactivity and radiation hazards assessment of soil samples from the area of Tuzla and Lukavac, Bosnia and Herzegovina a
a
a
Amira Kasumović , Feriz Adrović , Amela Kasić & Ema Hankić
a
a
Department of Physics, Faculty of Science, University of Tuzla, Tuzla, Bosnia and Herzegovina Published online: 07 Apr 2015.
Click for updates To cite this article: Amira Kasumović, Feriz Adrović, Amela Kasić & Ema Hankić (2015): Natural radioactivity and radiation hazards assessment of soil samples from the area of Tuzla and Lukavac, Bosnia and Herzegovina, Isotopes in Environmental and Health Studies, DOI: 10.1080/10256016.2015.1023798 To link to this article: http://dx.doi.org/10.1080/10256016.2015.1023798
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Downloaded by [New York University] at 13:36 18 May 2015
Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
Isotopes in Environmental and Health Studies, 2015 http://dx.doi.org/10.1080/10256016.2015.1023798
Natural radioactivity and radiation hazards assessment of soil samples from the area of Tuzla and Lukavac, Bosnia and Herzegovina Downloaded by [New York University] at 13:36 18 May 2015
Amira Kasumovi´c ∗ , Feriz Adrovi´c , Amela Kasi´c and Ema Hanki´c Department of Physics, Faculty of Science, University of Tuzla, Tuzla, Bosnia and Herzegovina (Received 31 August 2014; accepted 22 January 2015) The results of activity concentration measurements of natural occurring radioactive nuclides 238 U, 235 U, and 40 K in surface soil samples collected in the area of cities Tuzla and Lukavac, northeast region of Bosnia and Herzegovina were presented. Soil sampling was conducted at the localities that are situated in the vicinity of industrial zones of these cities. The measured activity was in the range from (8 ± 4) to (95 ± 28) Bq kg–1 for 238 U, from (0.41 ± 0.06) to (4.6 ± 0.7) Bq kg–1 for 235 U, from (7 ± 1) to (66 ± 7) Bq kg–1 for 232 Th, from (6 ± 1) to (55 ± 6) Bq kg–1 for 226 Ra, and from (83 ± 12) to (546 ± 55) Bq kg–1 for 40 K. In order to evaluate the radiological hazard of the natural radioactivity for people living near industrial zones, the absorbed dose rate, the annual effective dose and the radium equivalent activity have been calculated and compared with the internationally approved values. 232 Th, 226 Ra,
Keywords: Bosnia and Herzegovina; gamma spectrometry; natural radioactivity; radiation hazards; radioactive nuclides; soil
1.
Introduction
The largest part of radiation received by the world population originates from natural sources of radiation. Exposure to most of this radiation is inevitable, and people are exposed to radiation in two different ways: externally or internally. The terrestrial sources of radiation are responsible for most of human exposure to natural radiation, under normal circumstances. They include more than five-sixths of the annual effective dose absorbed by individuals, while the rest is mostly covered by cosmic radiation. It is estimated that the cosmic rays cause the effective dose about 0.38 mSv a–1 , while natural terrestrial sources, externally and internally, corresponding to the annual effective dose around 2 mSv. The external radiation and terrestrial gamma rays have an annual effective dose of 0.46 mSv, with less than 15 % achieved outdoors [1]. In order to estimate population exposure to radiation sources, a lot of attention is given to the research of natural environmental radiation and especially to the radioactivity in soil. Natural environmental radioactivity arises mainly from primordial radioactive nuclides such as 40 K and the nuclides from the 232 Th and 238 U series. The main objective of this study was to examine the influence of technologically enhanced natural radioactivity on radiation levels at the investigated area. Gamma-spectrometry analyses *Corresponding author. Email: [email protected] © 2015 Taylor & Francis
2
A. Kasumovi´c et al.
of soil samples and assessment of the absorbed dose rate, the annual effective dose and the radium equivalent activity were performed. This is the first case report about the natural radioactivity and the influence of technologically enhanced natural radioactivity on radiation levels at the investigated area.
2.
Downloaded by [New York University] at 13:36 18 May 2015
2.1.
Materials and methods Study area
The cities of Tuzla and Lukavac are situated in the northeast of Bosnia and Herzegovina and territorially belong to the Tuzla Canton. This area has various natural resources where coal and rock salt are predominant. The salt deposit is the only one of its kind in Bosnia and Herzegovina, and this area is also very well known for coal reserves and therefore very important in the energy sector. Exploitation of mineral resources and other materials has enabled the development of industries such as production and processing of coal, electricity generation, the salt-chemical industry, metal and electrical industry, as well as the construction industry [2]. A lot of these industrial facilities are located in the cities of Tuzla and Lukavac, mainly in urban areas. Intensive exploitation and technological processes in industrial production disturb the ecological balance of these cities and can lead to a significant redistribution of natural radioactivity [3–5]. 2.2.
Experimental procedure
The samples were collected in the area of Tuzla near the thermal power plant (TPP), as a potential cause of enhanced natural radioactivity, while in Lukavac near the cement factory, the factory of soda, the coke plant, as well as in the vicinity of Lake Modrac (Figure 1). The soil samples were taken from the surface layer of soil (0–5 cm depth level), uncultivated as well as cultivated land, close to the industrial facilities, from lawns and arable lands or from yards and gardens of nearby houses. The geographic coordinates of the sampling locations are presented in Table 1. Samples (total 31) were packed into plastic bags. In the laboratory, the plant material and rock fragments were removed. The samples were first dried at room temperature and then crushed, ground and dried at 105 °C. Next, samples were sieved through a 2 mm sieve and transferred to 450 cm3 Marinelli beakers, sealed and stored for a minimum of 30 days in order to achieve radioactivity equilibrium between 226 Ra, 222 Rn and their short-lived decay products. The radioactivity of these samples was measured using following detector systems: • a HP Ge detector with a relative efficiency of 23 % and a resolution of 1.8 keV at 1332 keV. Efficiency calibration was performed using reference sample MIX-OMH-SZ (National Office of Measures, Budapest) (used for samples 1–21 in Table 2). • a HP Ge detector with a relative efficiency of 32 % and a resolution of 1.86 keV at 1332 keV. Efficiency calibration was performed using the reference sample MGS-6-1035 (CANBERRA) (used for samples 22–31 in Table 2). Spectrum of every soil sample was collected for 86,000 s. GENIE 2000 software (Canberra) was used. The activity of 40 K was determined from its gamma line at 1460.2 keV. The activity of 226 Ra was determined from gamma line at 609.3 keV of the isotope 214 Bi and from gamma line at 351.92 keV of the isotope 214 Pb. The activity of 232 Th was determined from gamma lines at 911.2 and 338.32 keV of the isotope 228 Ac. The activity of 235 U was determined using peak at
Downloaded by [New York University] at 13:36 18 May 2015
Isotopes in Environmental and Health Studies
Figure 1.
3
Map of Bosnia and Herzegovina with sampling locations in Tuzla and Lukavac.
Table 1. Geographic coordinates and description of the sampling locations. Number of sample
Location
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
LK1 LK2 LK3 LK4 LK5 LK6 LK7 TZ1 TZ2 TZ3 TZ4 TZ5 TZ6 TZ7 TZ8 TZ9 TZ10 TZ11 TZ12 TZ13 TZ14 LK8 LK9 LK10 LK11 LK12 LK13 LK14 LK15 LK16 LK17
Latitude [N]
Longitude [E]
44.4938 44.4929 44.4924 44.4941 44.5269 44.5271 44.5275 44.5163 44.5168 44.5179 44.5166 44.5223 44.5221 44.5237 44.5242 44.5231 44.5236 44.5221 44.5212 44.5212 44.5259 44.5277 44.5282 44.5282 44.5312 44.5269 44.5244 44.5436 44.5547 44.5498 44.5347
18.4833 18.4811 18.4807 18.4838 18.5242 18.5244 18.5242 18.6069 18.6086 18.6099 18.6113 18.5999 18.5997 18.6001 18.5998 18.5995 18.5997 18.5948 18.5927 18.5985 18.6097 18.5297 18.5265 18.5273 18.5269 18.5353 18.5326 18.5033 18.5045 18.5127 18.5294
Description of location SW shore of Lake Modrac SW shore of Lake Modrac SW shore of Lake Modrac SW shore of Lake Modrac West of Lukavac Cement Plant West of Lukavac Cement Plant West of Lukavac Cement Plant South-east of Tuzla TPP South-east of Tuzla TPP South-east of Tuzla TPP South-east of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP SW of Tuzla TPP SW of Tuzla TPP North of Lukavac Cement Plant North of Lukavac Cement Plant North of Lukavac Cement Plant Close to Lukavac Sode Plant NE of Lukavac Cement Plant SE of Lukavac Cement Plant SW of Lukavac Coke Plant North of Lukavac Coke Plant East of Lukavac Coke Plant Central city park in Lukavac
186 keV corrected for 226 Ra contribution, according to Equation (1): A(U − 235) =
N(186 keV) − A(Ra − 226) · ε186 keV · PRa−226(186.21 keV) · m · t , m · tPU−235(185.72 keV) ε186 keV
(1)
where N(186 keV) is the total counts for the 186 keV doublet, A(U-235) and A(Ra-226) are the specific activities of 235 U and 226 Ra, respectively, 186keV is the detection efficiency of the
4
A. Kasumovi´c et al.
186 keV energy line, PU−235(185.72keV) and PRa−226(186.21keV) are the emission probabilities of the 185.72 and 186.21 keV gamma lines of 235 U and 226 Ra, respectively, t is the counting time and m is the mass of sample. The activity of 238 U was determined from gamma line at 1001.03 keV of the 234 Pa. The activity of 137 Cs was determined from its gamma line at 661.66 keV [6–8]. 2.3.
Assessment of radiation hazards due to natural radioactivity
Downloaded by [New York University] at 13:36 18 May 2015
The measured values of specific activity of 40 K, 232 Th and 226 Ra were used to assess the radiological hazard associated with the absorbed gamma dose rate in air and the annual effective dose from terrestrial gamma radiation [3,9–11]. The gamma absorbed dose rate in air originating from terrestrial sources at one metre above the ground level was calculated using the following formula [1,9,10]: DI = 0.462 · ARa + 0.042 · AK + 0.604 · ATh ,
(2)
where D is the gamma absorbed dose rate in air in nGy h–1 , ARa , ATh and AK are specific activities of 226 Ra, 232 Th and 40 K in soil samples in Bq kg–1 . The contribution of other natural radioactive nuclides is considered to be negligible. Considering the presence of 137 Cs in the studied soil samples, the gamma absorbed dose rate in air was calculated using the following formula [1,10]: DII = 0.427 · ARa + 0.043 · AK + 0.662 · ATh + 0.03 · ACs .
(3)
Based on the results of the gamma absorbed dose rate in air obtained in this way, the values of the annual effective dose were estimated. It was assumed that the absorbed-to-effective dose conversion factor for adults is 0.7 SvGy−1 and the outdoor occupancy time is 20 % of day time. The average annual effective doses were calculated using the following formulas [1,9,10]: Eoutdoor = D · F · t · 0.2 · 0.001,
(4)
Eindoor = D · F · t · 0.8 · 0.001,
(5)
where Eoutdoor and Eindoor are average annual effective doses (outdoor and indoor) in mSv, D is the gamma absorbed dose rate in air in nGy h–1 , t = 8760 h per year and F = 0.7 Sv Gy−1 is the absorbed-to-effective dose conversion factor for adults. Assessment of radiological hazards from external gamma radiation was made by calculating radium equivalent activity (Raeq ) using the following formula [1,9,10]: Raeq = ARa + 1.43 · ATh + 0.077 · AK .
(6)
It is based on the assumption that 370 Bq kg–1 of 226 Ra or 259 Bq kg–1 of 232 Th or 4810 Bq kg of 40 K produce the same gamma dose rate. The value of 370 Bq kg–1 for Raeq corresponds to an annual gamma dose of 1.5 mSv. A widely used hazard index (reflecting the external exposure) called the external radiation hazard index is defined as follows [1,9,12]: –1
Hex =
ARa ATh AK + + . 370 259 4810
(7)
In addition to the external radiation hazard index, radon and its short-lived products are also hazardous to the respiratory organs. The internal exposure to radon and its daughter products
Isotopes in Environmental and Health Studies
5
are quantified by the internal radiation hazard index, which is given by the following formula [1,9,12]: ARa ATh AK Hin = + + . (8) 185 259 4810 To account for the radiation hazards, the maximum permissible concentration for radium must be reduced to half of the normal limit appropriate to external exposures alone [13]. The values of the indexes (Hex , Hin ) must be less than unity for the radiation hazard to be negligible [9,12,13].
Downloaded by [New York University] at 13:36 18 May 2015
3.
Results and discussion
The measured specific activities of natural radioactive nuclides in soil samples are shown in Table 2. The activity of 238 U was in the range from (8 ± 4) to (95 ± 28) Bq kg–1 , with a mean value of 41 Bq kg–1 . The highest value of (95 ± 28) Bq kg–1 was found in the sample 15 (locality TZ8, Table 2) collected near the metering station Bukinje in the industrial zone of Tuzla. Relatively high values were found in samples 3 and 4 collected at localities near the accumulation Lake Modrac, then in sample 6 from the locality close to the cement factory storage in Lukavac. Also high values were observed in samples 13, 14 and 16, collected across the TPP in the community Ši´cki Brod. Table 2.
Specific activities of radioactive nuclides in soil samples in Bq kg−1 . Specific activities of radioactive nuclides (Bq kg−1 )
Number of sample
Location
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Mean value
LK1 LK2 LK3 LK4 LK5 LK6 LK7 TZ1 TZ2 TZ3 TZ4 TZ5 TZ6 TZ7 TZ8 TZ9 TZ10 TZ11 TZ12 TZ13 TZ14 LK8 LK9 LK10 LK11 LK12 LK13 LK14 LK15 LK16 LK17
238 U
39 53 72 63 39 54 26 43 51 47 51 42 56 57 95 62 44 37 49 26 42 16 31 8 18 13 35 26 17 33 18
± 14 ± 13 ± 17 ± 18 ±7 ± 16 ± 11 ± 11 ± 19 ± 11 ± 18 ± 12 ± 17 ± 14 ± 28 ± 14 ± 11 ± 10 ± 16 ± 11 ± 15 ±9 ± 12 ±4 ±9 ±9 ± 23 ± 10 ± 10 ± 15 ±9 41
235 U
2.3 3.9 4.6 4.0 2.9 1.8 1.2 3.8 3.2 2.4 3.9 3.9 2.4 4.6 3.8 4.1 3.0 2.1 3.8 2.5 2.1 0.41 1.4 0.50 1.7 1.05 1.3 1.1 1.8 1.7 1.4
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 3
0.4 0.6 0.7 0.6 0.4 0.3 0.2 0.6 0.6 0.4 0.6 0.6 0.4 0.7 0.7 0.5 0.4 0.4 0.6 0.4 0.3 0.06 0.2 0.08 0.2 0.15 0.2 0.1 0.2 0.2 0.2
232 Th
38 ± 53 ± 66 ± 52 ± 17 ± 13 ± 11 ± 44 ± 34 ± 26 ± 34 ± 50 ± 36 ± 48 ± 43 ± 52 ± 42 ± 32 ± 44 ± 26 ± 30 ± 7± 25 ± 7± 17 ± 18 ± 24 ± 21 ± 17 ± 31 ± 25 ± 32
5 6 7 6 3 2 2 5 5 3 4 6 4 7 5 6 5 4 5 3 4 2 5 1 4 4 5 5 4 7 5
226 Ra
35 ± 46 ± 55 ± 49 ± 35 ± 30 ± 19 ± 36 ± 40 ± 38 ± 24 ± 47 ± 32 ± 51 ± 45 ± 41 ± 46 ± 33 ± 44 ± 27 ± 31 ± 5.6 ± 25 ± 7.5 ± 20 ± 18 ± 28 ± 22 ± 18 ± 30 ± 20 ± 32
4 5 6 5 4 3 2 4 5 4 3 5 4 5 4 4 5 3 4 3 3 0.5 2 0.5 1 1 1 1 1 1 1
40 K
137 Cs
347 ± 35 281 ± 28 480 ± 48 416 ± 42 191 ± 28 167 ± 17 83 ± 12 466 ± 47 305 ± 30 397 ± 40 380 ± 38 459 ± 46 546 ± 55 536 ± 59 442 ± 44 458 ± 46 374 ± 37 360 ± 36 437 ± 44 365 ± 37 450 ± 45 145 ± 11 276 ± 18 111 ± 9 200 ± 13 158 ± 12 298 ± 20 293 ± 19 206 ± 14 339 ± 22 309 ± 20 331
109 ± 11 42 ± 4 47 ± 5 67 ± 7 2.4 ± 0.4 1.3 ± 0.2 1.0 ± 0.2 59 ± 6 130 ± 13 176 ± 18 106 ± 11 56 ± 6 16 ± 2 32 ± 3 52 ± 5 20 ± 2 42 ± 4 12 ± 1.4 23 ± 2 10 ± 1 9±1 < 0.25 6.3 ± 1.4 < 0.24 43.9 ± 9.8 16.5 ± 3.7 3.8 ± 0.8 26.2 ± 5.8 6.4 ± 1.4 16.2 ± 3.6 16.5 ± 3.7 37
Downloaded by [New York University] at 13:36 18 May 2015
6
A. Kasumovi´c et al.
The specific activity of 235 U was in the range from (0.41 ± 0.06) to (4.6 ± 0.7) Bq kg–1 , with a mean value of 3 Bq kg–1 . The highest value of 4.6 Bq kg–1 was observed in samples 3 and 14, collected near Lake Modrac and across the TPP, respectively. Rather high values within the range from 3.8 to 4.1 Bq kg–1 were determined in samples collected south-east of the TPP (8 and 11), then in the community Ši´cki Brod (12, 16 and 19) and around Lake Modrac (2 and 4). The specific activity of 232 Th was in the range from (7 ± 1) to (66 ± 7) Bq kg–1 , with a mean value of 32 Bq kg–1 . Specific activities of 50 Bq kg–1 and higher were found in samples collected around Lake Modrac (2, 3 and 4) and near the TPP in Tuzla (12, 14 and 16). The specific activity of 226 Ra was in the range from (6 ± 1) to (55 ± 6) Bq kg–1 , with a mean value of 32 Bq kg–1 . The highest values, ranging from 41–51 Bq kg–1 , were observed in samples collected near the Lake Modrac and the TPP in the community Ši´cki Brod, Tuzla. The average value of 238 U/226 Ra ratio in UNSCEAR report is about 1.03 [1]. For some soil samples the results show a 238 U/226 Ra ratio of more than unity with an average value of 1.28. The obtained values for the specific activities of 238 U and 226 Ra and the 238 U/226 Ra ratio are similar to the values in earlier studies for the region of Bosnia and Herzegovina and in neighboring countries [14–18]. The specific activity of 40 K was in the range from (83 ± 12) to (546 ± 55) Bq kg–1 , with a mean value of 331 Bq kg–1 . The highest value was found in sample 13, collected across the TPP in Ši´cki Brod. The lowest value of 83 Bq kg–1 was found in sample 7, collected from cement bags close to the cement factory and represents the deposit of dust, not the typical soil. It can be noticed that samples collected near the TPP in the industrial zone of Tuzla have higher levels of specific activity of all examined natural radioactive nuclides in comparison to other samples. One of the reasons is that samples collected near the TPP are exposed to fly ash released from chimneys. Nearby are the landfills of ash and slag, which also affect the level of radioactivity, since re-suspended dust from the landfill reaches inhabited areas. In samples collected around Lake Modrac, relatively higher values of specific activities were observed. Although there are no industrial activities around, the lake accumulates effluents from industrial facilities. The man-made radioisotope 137 Cs was identified in almost all samples. The specific activity was in the range from (1.0 ± 0.1) to (176 ± 18) Bq kg–1 , with a mean value of 37.1 Bq kg–1 . The highest values, ranging from 106–176 Bq kg–1 were observed in samples collected near the TPP in the community Ši´cki Brod, Tuzla (9,10 and 11) and near the accumulation Lake Modrac (1). This radionuclide originates from nuclear weapons test fall-out and after 1986, mostly from the accident of the nuclear power plant in Chernobyl. The obtained values are in good agreement
Table 3.
Specific activity of natural radioactive nuclides in soil in some European countries [12, 13]. Specific activities of radioactive nuclides (Bq kg−1 )
Country Albania Bulgaria Montenegro Czech Greece Croatia Hungary Macedonia Poland Romania Slovenia World average Present study
238 U
232 Th
226 Ra
40 K
34 (2.5–141) 40 (8–190)
18.3 (0.8–61) 30 (7–160) 23.7 (9–74) 41 (18–168) 28 (1–193) 37 (10–72) 28 (12–45) 25 (19.8–37.9) 24.7 (3.7–86) 38 (11–75) 35 (2–90) 30 (11–64) 32 (7–66)
45 (12–210) 29.3 (7–166) 44 (18–275) 29 (1–310) 43 (18–80) 33 (14–76) 23.4 (0–31.7) 25.2 (4.2–124) 32 (8–60) 41(2–208) 35 (17–60) 32 (6–55)
348 (91–665) 400 (40–800) 246 (78–480) 613 (262–1599) 383 (12–1570) 423 (107–748) 370 (79–570) 456 (0–699) 410 (123–1020) 490 (250–1100) 374 (15–1410) 400 (140–850) 331 (83–546)
45 (10–190) 53 (19–135) 29 (12–66) 36.9 (11.5–92.7) 25.2 (4.2–124) 32 (8–60) 35 (16–110) 41 (8–95)
Downloaded by [New York University] at 13:36 18 May 2015
Isotopes in Environmental and Health Studies
7
with the values in earlier studies for some region of Bosnia and Herzegovina and in neighboring countries [16–19]. According to UNSCEAR the world average values of specific activity for natural radioactive nuclides in soil samples are as follows: 35 Bq kg–1 for 238 U, 30 Bq kg–1 for 232 Th, 35 Bq kg–1 for 226 Ra and 400 Bq kg–1 for 40 K [1]. Our results do not differ significantly from those mentioned above. In Table 3, values from some countries in Europe are listed [1,20]. Based on the measured specific activities of 40 K, 232 Th and 226 Ra in soil samples (Table 2), the gamma absorbed dose rate in air, the annual effective dose, radium equivalent activity, external and internal hazard index were calculated using formulas (2)–(8). These results are shown in Table 4. The gamma absorbed dose rates in air were found to be between 12.1 and 85.4 nGy h–1 , with an arithmetic mean of 47.9 nGy h–1 . The relatively high values of the gamma absorbed dose rates in air were found in samples collected near the Lake Modrac and near the TPP in Ši´cki Brod. According to UNSCEAR, the world average gamma absorbed dose rate in air is 51 nGy h–1 (as calculated) or within the range from 18 to 93 nGy h–1 with a mean value of 57 nGy h–1 (as directly measured) [1]. If the absorbed dose rate is calculated by formula (2), it can be noticed that 137 Cs contributes little to the total dose arising from environmental background and can be neglected. Calculated values of the annual outdoor effective dose on investigated areas are in the range from 0.01 to 0.10 mSv with a mean value of 0.06 mSv, which is comparable with the
Table 4. The gamma absorbed dose rate in air, the annual effective dose, radium equivalent activity, external and internal hazard index. DI Number of sample
Location
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Mean value
LK1 LK2 LK3 LK4 LK5 LK6 LK7 TZ1 TZ2 TZ3 TZ4 TZ5 TZ6 TZ7 TZ8 TZ9 TZ10 TZ11 TZ12 TZ13 TZ14 LK8 LK9 LK10 LK11 LK12 LK13 LK14 LK15 LK16 LK17
DII
Eoutdoor
Eindoor
Raeq
nGyh−1
nGyh−1
mSv
mSv
Bq kg−1
Hex
Hin
53.7 65.1 85.4 71.5 34.5 28.7 18.9 62.8 51.8 49.9 47.6 71.2 59.5 75.1 65.3 69.6 62.3 49.7 65.3 43.5 51.3 12.7 38.2 12.1 27.7 25.7 39.9 35.3 26.9 46.5 36.8 47.9
58.3 68.1 89.2 75.2 34.5 28.6 19.0 66.3 56.6 55.8 52.3 74.6 61.5 77.6 68.2 72.2 64.8 51.1 67.4 44.7 52.7 13.0 39.2 12.4 29.5 26.8 40.7 36.8 27.6 48.1 38.4 50.04
0.07 0.08 0.10 0.09 0.04 0.04 0.02 0.08 0.06 0.06 0.06 0.09 0.07 0.09 0.08 0.09 0.08 0.06 0.08 0.05 0.06 0.02 0.05 0.01 0.03 0.03 0.05 0.04 0.03 0.06 0.05 0.06
0.26 0.32 0.42 0.35 0.17 0.14 0.09 0.31 0.25 0.24 0.23 0.35 0.29 0.37 0.32 0.34 0.31 0.24 0.32 0.21 0.25 0.06 0.19 0.06 0.14 0.13 0.20 0.17 0.13 0.23 0.18 0.23
116.1 143.4 186.3 155.4 74.0 61.4 41.1 134.8 112.1 105.7 101.9 153.8 125.5 160.9 140.5 150.6 134.9 106.5 140.6 92.3 108.6 26.2 81.9 25.6 59.2 55.7 85.1 74.9 57.3 99.8 78.4
0.31 0.39 0.50 0.42 0.20 0.17 0.11 0.36 0.30 0.29 0.28 0.42 0.34 0.43 0.38 0.41 0.36 0.29 0.38 0.25 0.29 0.07 0.22 0.07 0.16 0.15 0.23 0.20 0.15 0.27 0.21
0.41 0.51 0.65 0.55 0.29 0.25 0.16 0.46 0.41 0.39 0.34 0.54 0.43 0.57 0.50 0.52 0.49 0.38 0.50 0.32 0.38 0.09 0.29 0.09 0.21 0.20 0.31 0.26 0.20 0.35 0.26
8
A. Kasumovi´c et al.
world averages [7]. The annual indoor effective doses are in the range from 0.06 to 0.42 mSv with a mean value of 0.23 mSv, which is lower than the world average [1]. The values of Raeq vary from 26.2 to 186.3 Bq kg–1 , which is below the maximum permissible value of 370 Bq kg–1 . The values of the external radiation hazard index, Hex , ranged from 0.07 to 0.50, with an average value of 0.28. The internal radiation hazard index Hin values ranged from 0.09 to 0.65, with an average value of 0.36. These values for all samples studied in this work are less than unity.
4.
Conclusions
The results of activity concentration measurements of natural occurring radioactive nuclides U, 235 U, 232 Th, 226 Ra and 40 K in soil samples from the area of the cities Tuzla and Lukavac, Bosnia and Herzegovina are presented. Soil sampling locations were chosen near the industrial areas of these cities in order to determine the influence of industry on the natural radioactivity in this region. The results show that relatively higher values of specific activity of measured radioactive nuclides in comparison to other samples are present in soil samples collected in the vicinity of the coal TPP in the industrial zone of Tuzla as well as nearby the accumulating Lake Modrac. Presented results do not differ significantly from the world average ones. In general, it can be noticed that results do not show the enhancement of natural radiation background in the vicinity of investigated industrial facilities. The calculated value of the gamma absorbed dose rate in air varies from 12.1 to 85.4 nGy h–1 , with an average of 47.9 nGy h–1 . The estimated value of the annual outdoor effective dose is in the range from 0.01 to 0.10 mSv with a mean value of 0.06 mSv, what falls within the range of the world average. The estimated value of the annual indoor effective dose also falls within the range of the world average.
Downloaded by [New York University] at 13:36 18 May 2015
238
Disclosure statement No potential conflict of interest was reported by the authors. References [1] UNSCEAR. Report to the General Assembly, with scientific annexes, Sources and effects of ionizing radiation. New York: United Nations Scientific Committee on the Effects of Atomic Radiation; 2000. [2] Offical Web Page of Tuzla Canton. Economy of Tuzla Canton. [Internet] 2010. [cited 2013 Feb 1]. Available from: http://vladatk.kim.ba/OKantonu/privreda.htm. Bosnian. [3] Mondal T, Sengupta D, Mandal A. Natural radioactivity of ash and coal in major thermal power plants of West Bengal, India. Curr Sci India. 2006;91:1387–1393. [4] Papp Z, Dezs˝o Z, Daróczy S. Significant radioactive contamination of soil around a coal-fired thermal power plant. J Environ Radioactiv. 2002;59:191–205. [5] Adrovic F, Proki´c M, Ninkovi´c MM, Glisi´c R. Measurements of environmental background radiation at location of coal-fired power plants. Radiat Prot Dosim. 2004;112:439–442. [6] Ebaid YY. Use of gamma-ray spectrometry for uranium isotopic analysis in environmental samples. Rom J Phys. 2010;55:69–74. ˇ [7] Slivka J, Bikit I, Veskovi´c M, Conki´ c Lj. Gamma-spectrometry, special methods and applications. Serbia: University of Novi Sad; 2001. Serbian. [8] Gilmore G. Practical gamma-ray spectrometry. 2nd edition. West Sussex, England: John Wiley & Sons, Ltd.; 2008. Chapter 16, Gamma spectrometry of naturally occurring radioactive materials (NORM); p. 316–328. [9] Diab HM, Nouh SA, Hamdy A, El-Fiki SA. Evaluation of natural radioactivity in a cultivated area around a fertilizer factory. J Nucl Radiat. 2008;3:53–62. ´ [10] Dołha´nczuk-Sródka A. Estimation of external gamma radiation dose in the area of Bory Stobrawskie forests (PL). Environ Monit Assess. 2012;184:5773–5779. [11] Hafezi S, Amidi J, Attarilar A. Concentration of natural radionuclides in soil and assessment of external exposure to the public in Tehran, Iran. J Radiat Res. 2005;3:85–88.
Downloaded by [New York University] at 13:36 18 May 2015
Isotopes in Environmental and Health Studies
9
[12] Almayahi BA, Tajuddin AA, Jaafar MS. Radiation hazard indices of soil and water samples in Northern Malaysian Peninsula. Appl Radiat Isot. 2012;70:2652–2660. [13] Jabbar A, Arshed W, Bhatti AS, Ahmad SS, Akhter P, Rehman SU, Anjum MI. Measurement of soil radioactivity levels and radiation hazard assessment in southern Rechna interfluvial region, Pakistan. Environ Monit Assess. 2010;169:429–438. [14] Institute for Public Health FB&H. Radioaktivnost u životnoj sredini Federacije Bosne i Hercegovine za 2012. godinu [Radioactivity in environment of the Federation of Bosnia and Herzegovina in 2012]. Sarajevo; 2013. Bosnian. [15] Institute for Public Health FB&H. Radioaktivnost u životnoj sredini Federacije Bosne i Hercegovine za 2013. godinu [Radioactivity in environment of the Federation of Bosnia and Herzegovina in 2012]. Sarajevo; 2014. Bosnian. [16] Huremovi´c J, Horvat M, Ruždi´c E, Ja´cimovi´c R. Istraživanje radiokontaminacije grada Sarajeva i njegove okolice s obzirom na radionuklide [Analysis of the radiopollution of the City of Sarajevo and its surrounding area with regard to radionuclides]. Kem Ind. 2009;58:165–170. Croatian. [17] Jankovi´c MM, Todorovi´c DJ, Savanovi´c MB, Nikoli´c SM, Vocki´c ND. Radioactivity of the soil in Republic of Srpska. In: Proceedings of the French–Serbian European summer university: Renewable energy sources and environment–multidisciplinary aspect; 2006 Oct 17–24; Vrnjacka banja, Serbia. p. 169–172. [18] Jankovic M, Todorovic D, Savanovic M. Radioactivity measurements in soil samples collected in the Republic of Srpska. Radiat Meas. 2008;43:1448–1452. [19] Deljki´c D, Vidic A, Mari´c S, Ili´c Z, Sirko D. Radioactivity of the soil in Federation Bosnia and Herzegovina. In: Garaj-Vrhovac, V, Kopjar, N, Miljanic, S, editors. Proceedings of the Sixth Symposium of the Croatian Radiation Protection Association; 2005 Apr 18–20; Stubicke Toplice, Croatia. p. 358–362. [20] UNSCEAR. Report to the general assembly, with scientific annexes, sources and effects of ionizing radiation. New York: United Nations Scientific Committee on the Effects of Atomic Radiation; 2008.
Isotopes in Environmental and Health Studies Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gieh20
Natural radioactivity and radiation hazards assessment of soil samples from the area of Tuzla and Lukavac, Bosnia and Herzegovina a
a
a
Amira Kasumović , Feriz Adrović , Amela Kasić & Ema Hankić
a
a
Department of Physics, Faculty of Science, University of Tuzla, Tuzla, Bosnia and Herzegovina Published online: 07 Apr 2015.
Click for updates To cite this article: Amira Kasumović, Feriz Adrović, Amela Kasić & Ema Hankić (2015): Natural radioactivity and radiation hazards assessment of soil samples from the area of Tuzla and Lukavac, Bosnia and Herzegovina, Isotopes in Environmental and Health Studies, DOI: 10.1080/10256016.2015.1023798 To link to this article: http://dx.doi.org/10.1080/10256016.2015.1023798
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Downloaded by [New York University] at 13:36 18 May 2015
Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
Isotopes in Environmental and Health Studies, 2015 http://dx.doi.org/10.1080/10256016.2015.1023798
Natural radioactivity and radiation hazards assessment of soil samples from the area of Tuzla and Lukavac, Bosnia and Herzegovina Downloaded by [New York University] at 13:36 18 May 2015
Amira Kasumovi´c ∗ , Feriz Adrovi´c , Amela Kasi´c and Ema Hanki´c Department of Physics, Faculty of Science, University of Tuzla, Tuzla, Bosnia and Herzegovina (Received 31 August 2014; accepted 22 January 2015) The results of activity concentration measurements of natural occurring radioactive nuclides 238 U, 235 U, and 40 K in surface soil samples collected in the area of cities Tuzla and Lukavac, northeast region of Bosnia and Herzegovina were presented. Soil sampling was conducted at the localities that are situated in the vicinity of industrial zones of these cities. The measured activity was in the range from (8 ± 4) to (95 ± 28) Bq kg–1 for 238 U, from (0.41 ± 0.06) to (4.6 ± 0.7) Bq kg–1 for 235 U, from (7 ± 1) to (66 ± 7) Bq kg–1 for 232 Th, from (6 ± 1) to (55 ± 6) Bq kg–1 for 226 Ra, and from (83 ± 12) to (546 ± 55) Bq kg–1 for 40 K. In order to evaluate the radiological hazard of the natural radioactivity for people living near industrial zones, the absorbed dose rate, the annual effective dose and the radium equivalent activity have been calculated and compared with the internationally approved values. 232 Th, 226 Ra,
Keywords: Bosnia and Herzegovina; gamma spectrometry; natural radioactivity; radiation hazards; radioactive nuclides; soil
1.
Introduction
The largest part of radiation received by the world population originates from natural sources of radiation. Exposure to most of this radiation is inevitable, and people are exposed to radiation in two different ways: externally or internally. The terrestrial sources of radiation are responsible for most of human exposure to natural radiation, under normal circumstances. They include more than five-sixths of the annual effective dose absorbed by individuals, while the rest is mostly covered by cosmic radiation. It is estimated that the cosmic rays cause the effective dose about 0.38 mSv a–1 , while natural terrestrial sources, externally and internally, corresponding to the annual effective dose around 2 mSv. The external radiation and terrestrial gamma rays have an annual effective dose of 0.46 mSv, with less than 15 % achieved outdoors [1]. In order to estimate population exposure to radiation sources, a lot of attention is given to the research of natural environmental radiation and especially to the radioactivity in soil. Natural environmental radioactivity arises mainly from primordial radioactive nuclides such as 40 K and the nuclides from the 232 Th and 238 U series. The main objective of this study was to examine the influence of technologically enhanced natural radioactivity on radiation levels at the investigated area. Gamma-spectrometry analyses *Corresponding author. Email: [email protected] © 2015 Taylor & Francis
2
A. Kasumovi´c et al.
of soil samples and assessment of the absorbed dose rate, the annual effective dose and the radium equivalent activity were performed. This is the first case report about the natural radioactivity and the influence of technologically enhanced natural radioactivity on radiation levels at the investigated area.
2.
Downloaded by [New York University] at 13:36 18 May 2015
2.1.
Materials and methods Study area
The cities of Tuzla and Lukavac are situated in the northeast of Bosnia and Herzegovina and territorially belong to the Tuzla Canton. This area has various natural resources where coal and rock salt are predominant. The salt deposit is the only one of its kind in Bosnia and Herzegovina, and this area is also very well known for coal reserves and therefore very important in the energy sector. Exploitation of mineral resources and other materials has enabled the development of industries such as production and processing of coal, electricity generation, the salt-chemical industry, metal and electrical industry, as well as the construction industry [2]. A lot of these industrial facilities are located in the cities of Tuzla and Lukavac, mainly in urban areas. Intensive exploitation and technological processes in industrial production disturb the ecological balance of these cities and can lead to a significant redistribution of natural radioactivity [3–5]. 2.2.
Experimental procedure
The samples were collected in the area of Tuzla near the thermal power plant (TPP), as a potential cause of enhanced natural radioactivity, while in Lukavac near the cement factory, the factory of soda, the coke plant, as well as in the vicinity of Lake Modrac (Figure 1). The soil samples were taken from the surface layer of soil (0–5 cm depth level), uncultivated as well as cultivated land, close to the industrial facilities, from lawns and arable lands or from yards and gardens of nearby houses. The geographic coordinates of the sampling locations are presented in Table 1. Samples (total 31) were packed into plastic bags. In the laboratory, the plant material and rock fragments were removed. The samples were first dried at room temperature and then crushed, ground and dried at 105 °C. Next, samples were sieved through a 2 mm sieve and transferred to 450 cm3 Marinelli beakers, sealed and stored for a minimum of 30 days in order to achieve radioactivity equilibrium between 226 Ra, 222 Rn and their short-lived decay products. The radioactivity of these samples was measured using following detector systems: • a HP Ge detector with a relative efficiency of 23 % and a resolution of 1.8 keV at 1332 keV. Efficiency calibration was performed using reference sample MIX-OMH-SZ (National Office of Measures, Budapest) (used for samples 1–21 in Table 2). • a HP Ge detector with a relative efficiency of 32 % and a resolution of 1.86 keV at 1332 keV. Efficiency calibration was performed using the reference sample MGS-6-1035 (CANBERRA) (used for samples 22–31 in Table 2). Spectrum of every soil sample was collected for 86,000 s. GENIE 2000 software (Canberra) was used. The activity of 40 K was determined from its gamma line at 1460.2 keV. The activity of 226 Ra was determined from gamma line at 609.3 keV of the isotope 214 Bi and from gamma line at 351.92 keV of the isotope 214 Pb. The activity of 232 Th was determined from gamma lines at 911.2 and 338.32 keV of the isotope 228 Ac. The activity of 235 U was determined using peak at
Downloaded by [New York University] at 13:36 18 May 2015
Isotopes in Environmental and Health Studies
Figure 1.
3
Map of Bosnia and Herzegovina with sampling locations in Tuzla and Lukavac.
Table 1. Geographic coordinates and description of the sampling locations. Number of sample
Location
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
LK1 LK2 LK3 LK4 LK5 LK6 LK7 TZ1 TZ2 TZ3 TZ4 TZ5 TZ6 TZ7 TZ8 TZ9 TZ10 TZ11 TZ12 TZ13 TZ14 LK8 LK9 LK10 LK11 LK12 LK13 LK14 LK15 LK16 LK17
Latitude [N]
Longitude [E]
44.4938 44.4929 44.4924 44.4941 44.5269 44.5271 44.5275 44.5163 44.5168 44.5179 44.5166 44.5223 44.5221 44.5237 44.5242 44.5231 44.5236 44.5221 44.5212 44.5212 44.5259 44.5277 44.5282 44.5282 44.5312 44.5269 44.5244 44.5436 44.5547 44.5498 44.5347
18.4833 18.4811 18.4807 18.4838 18.5242 18.5244 18.5242 18.6069 18.6086 18.6099 18.6113 18.5999 18.5997 18.6001 18.5998 18.5995 18.5997 18.5948 18.5927 18.5985 18.6097 18.5297 18.5265 18.5273 18.5269 18.5353 18.5326 18.5033 18.5045 18.5127 18.5294
Description of location SW shore of Lake Modrac SW shore of Lake Modrac SW shore of Lake Modrac SW shore of Lake Modrac West of Lukavac Cement Plant West of Lukavac Cement Plant West of Lukavac Cement Plant South-east of Tuzla TPP South-east of Tuzla TPP South-east of Tuzla TPP South-east of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP West of Tuzla TPP SW of Tuzla TPP SW of Tuzla TPP North of Lukavac Cement Plant North of Lukavac Cement Plant North of Lukavac Cement Plant Close to Lukavac Sode Plant NE of Lukavac Cement Plant SE of Lukavac Cement Plant SW of Lukavac Coke Plant North of Lukavac Coke Plant East of Lukavac Coke Plant Central city park in Lukavac
186 keV corrected for 226 Ra contribution, according to Equation (1): A(U − 235) =
N(186 keV) − A(Ra − 226) · ε186 keV · PRa−226(186.21 keV) · m · t , m · tPU−235(185.72 keV) ε186 keV
(1)
where N(186 keV) is the total counts for the 186 keV doublet, A(U-235) and A(Ra-226) are the specific activities of 235 U and 226 Ra, respectively, 186keV is the detection efficiency of the
4
A. Kasumovi´c et al.
186 keV energy line, PU−235(185.72keV) and PRa−226(186.21keV) are the emission probabilities of the 185.72 and 186.21 keV gamma lines of 235 U and 226 Ra, respectively, t is the counting time and m is the mass of sample. The activity of 238 U was determined from gamma line at 1001.03 keV of the 234 Pa. The activity of 137 Cs was determined from its gamma line at 661.66 keV [6–8]. 2.3.
Assessment of radiation hazards due to natural radioactivity
Downloaded by [New York University] at 13:36 18 May 2015
The measured values of specific activity of 40 K, 232 Th and 226 Ra were used to assess the radiological hazard associated with the absorbed gamma dose rate in air and the annual effective dose from terrestrial gamma radiation [3,9–11]. The gamma absorbed dose rate in air originating from terrestrial sources at one metre above the ground level was calculated using the following formula [1,9,10]: DI = 0.462 · ARa + 0.042 · AK + 0.604 · ATh ,
(2)
where D is the gamma absorbed dose rate in air in nGy h–1 , ARa , ATh and AK are specific activities of 226 Ra, 232 Th and 40 K in soil samples in Bq kg–1 . The contribution of other natural radioactive nuclides is considered to be negligible. Considering the presence of 137 Cs in the studied soil samples, the gamma absorbed dose rate in air was calculated using the following formula [1,10]: DII = 0.427 · ARa + 0.043 · AK + 0.662 · ATh + 0.03 · ACs .
(3)
Based on the results of the gamma absorbed dose rate in air obtained in this way, the values of the annual effective dose were estimated. It was assumed that the absorbed-to-effective dose conversion factor for adults is 0.7 SvGy−1 and the outdoor occupancy time is 20 % of day time. The average annual effective doses were calculated using the following formulas [1,9,10]: Eoutdoor = D · F · t · 0.2 · 0.001,
(4)
Eindoor = D · F · t · 0.8 · 0.001,
(5)
where Eoutdoor and Eindoor are average annual effective doses (outdoor and indoor) in mSv, D is the gamma absorbed dose rate in air in nGy h–1 , t = 8760 h per year and F = 0.7 Sv Gy−1 is the absorbed-to-effective dose conversion factor for adults. Assessment of radiological hazards from external gamma radiation was made by calculating radium equivalent activity (Raeq ) using the following formula [1,9,10]: Raeq = ARa + 1.43 · ATh + 0.077 · AK .
(6)
It is based on the assumption that 370 Bq kg–1 of 226 Ra or 259 Bq kg–1 of 232 Th or 4810 Bq kg of 40 K produce the same gamma dose rate. The value of 370 Bq kg–1 for Raeq corresponds to an annual gamma dose of 1.5 mSv. A widely used hazard index (reflecting the external exposure) called the external radiation hazard index is defined as follows [1,9,12]: –1
Hex =
ARa ATh AK + + . 370 259 4810
(7)
In addition to the external radiation hazard index, radon and its short-lived products are also hazardous to the respiratory organs. The internal exposure to radon and its daughter products
Isotopes in Environmental and Health Studies
5
are quantified by the internal radiation hazard index, which is given by the following formula [1,9,12]: ARa ATh AK Hin = + + . (8) 185 259 4810 To account for the radiation hazards, the maximum permissible concentration for radium must be reduced to half of the normal limit appropriate to external exposures alone [13]. The values of the indexes (Hex , Hin ) must be less than unity for the radiation hazard to be negligible [9,12,13].
Downloaded by [New York University] at 13:36 18 May 2015
3.
Results and discussion
The measured specific activities of natural radioactive nuclides in soil samples are shown in Table 2. The activity of 238 U was in the range from (8 ± 4) to (95 ± 28) Bq kg–1 , with a mean value of 41 Bq kg–1 . The highest value of (95 ± 28) Bq kg–1 was found in the sample 15 (locality TZ8, Table 2) collected near the metering station Bukinje in the industrial zone of Tuzla. Relatively high values were found in samples 3 and 4 collected at localities near the accumulation Lake Modrac, then in sample 6 from the locality close to the cement factory storage in Lukavac. Also high values were observed in samples 13, 14 and 16, collected across the TPP in the community Ši´cki Brod. Table 2.
Specific activities of radioactive nuclides in soil samples in Bq kg−1 . Specific activities of radioactive nuclides (Bq kg−1 )
Number of sample
Location
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Mean value
LK1 LK2 LK3 LK4 LK5 LK6 LK7 TZ1 TZ2 TZ3 TZ4 TZ5 TZ6 TZ7 TZ8 TZ9 TZ10 TZ11 TZ12 TZ13 TZ14 LK8 LK9 LK10 LK11 LK12 LK13 LK14 LK15 LK16 LK17
238 U
39 53 72 63 39 54 26 43 51 47 51 42 56 57 95 62 44 37 49 26 42 16 31 8 18 13 35 26 17 33 18
± 14 ± 13 ± 17 ± 18 ±7 ± 16 ± 11 ± 11 ± 19 ± 11 ± 18 ± 12 ± 17 ± 14 ± 28 ± 14 ± 11 ± 10 ± 16 ± 11 ± 15 ±9 ± 12 ±4 ±9 ±9 ± 23 ± 10 ± 10 ± 15 ±9 41
235 U
2.3 3.9 4.6 4.0 2.9 1.8 1.2 3.8 3.2 2.4 3.9 3.9 2.4 4.6 3.8 4.1 3.0 2.1 3.8 2.5 2.1 0.41 1.4 0.50 1.7 1.05 1.3 1.1 1.8 1.7 1.4
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 3
0.4 0.6 0.7 0.6 0.4 0.3 0.2 0.6 0.6 0.4 0.6 0.6 0.4 0.7 0.7 0.5 0.4 0.4 0.6 0.4 0.3 0.06 0.2 0.08 0.2 0.15 0.2 0.1 0.2 0.2 0.2
232 Th
38 ± 53 ± 66 ± 52 ± 17 ± 13 ± 11 ± 44 ± 34 ± 26 ± 34 ± 50 ± 36 ± 48 ± 43 ± 52 ± 42 ± 32 ± 44 ± 26 ± 30 ± 7± 25 ± 7± 17 ± 18 ± 24 ± 21 ± 17 ± 31 ± 25 ± 32
5 6 7 6 3 2 2 5 5 3 4 6 4 7 5 6 5 4 5 3 4 2 5 1 4 4 5 5 4 7 5
226 Ra
35 ± 46 ± 55 ± 49 ± 35 ± 30 ± 19 ± 36 ± 40 ± 38 ± 24 ± 47 ± 32 ± 51 ± 45 ± 41 ± 46 ± 33 ± 44 ± 27 ± 31 ± 5.6 ± 25 ± 7.5 ± 20 ± 18 ± 28 ± 22 ± 18 ± 30 ± 20 ± 32
4 5 6 5 4 3 2 4 5 4 3 5 4 5 4 4 5 3 4 3 3 0.5 2 0.5 1 1 1 1 1 1 1
40 K
137 Cs
347 ± 35 281 ± 28 480 ± 48 416 ± 42 191 ± 28 167 ± 17 83 ± 12 466 ± 47 305 ± 30 397 ± 40 380 ± 38 459 ± 46 546 ± 55 536 ± 59 442 ± 44 458 ± 46 374 ± 37 360 ± 36 437 ± 44 365 ± 37 450 ± 45 145 ± 11 276 ± 18 111 ± 9 200 ± 13 158 ± 12 298 ± 20 293 ± 19 206 ± 14 339 ± 22 309 ± 20 331
109 ± 11 42 ± 4 47 ± 5 67 ± 7 2.4 ± 0.4 1.3 ± 0.2 1.0 ± 0.2 59 ± 6 130 ± 13 176 ± 18 106 ± 11 56 ± 6 16 ± 2 32 ± 3 52 ± 5 20 ± 2 42 ± 4 12 ± 1.4 23 ± 2 10 ± 1 9±1 < 0.25 6.3 ± 1.4 < 0.24 43.9 ± 9.8 16.5 ± 3.7 3.8 ± 0.8 26.2 ± 5.8 6.4 ± 1.4 16.2 ± 3.6 16.5 ± 3.7 37
Downloaded by [New York University] at 13:36 18 May 2015
6
A. Kasumovi´c et al.
The specific activity of 235 U was in the range from (0.41 ± 0.06) to (4.6 ± 0.7) Bq kg–1 , with a mean value of 3 Bq kg–1 . The highest value of 4.6 Bq kg–1 was observed in samples 3 and 14, collected near Lake Modrac and across the TPP, respectively. Rather high values within the range from 3.8 to 4.1 Bq kg–1 were determined in samples collected south-east of the TPP (8 and 11), then in the community Ši´cki Brod (12, 16 and 19) and around Lake Modrac (2 and 4). The specific activity of 232 Th was in the range from (7 ± 1) to (66 ± 7) Bq kg–1 , with a mean value of 32 Bq kg–1 . Specific activities of 50 Bq kg–1 and higher were found in samples collected around Lake Modrac (2, 3 and 4) and near the TPP in Tuzla (12, 14 and 16). The specific activity of 226 Ra was in the range from (6 ± 1) to (55 ± 6) Bq kg–1 , with a mean value of 32 Bq kg–1 . The highest values, ranging from 41–51 Bq kg–1 , were observed in samples collected near the Lake Modrac and the TPP in the community Ši´cki Brod, Tuzla. The average value of 238 U/226 Ra ratio in UNSCEAR report is about 1.03 [1]. For some soil samples the results show a 238 U/226 Ra ratio of more than unity with an average value of 1.28. The obtained values for the specific activities of 238 U and 226 Ra and the 238 U/226 Ra ratio are similar to the values in earlier studies for the region of Bosnia and Herzegovina and in neighboring countries [14–18]. The specific activity of 40 K was in the range from (83 ± 12) to (546 ± 55) Bq kg–1 , with a mean value of 331 Bq kg–1 . The highest value was found in sample 13, collected across the TPP in Ši´cki Brod. The lowest value of 83 Bq kg–1 was found in sample 7, collected from cement bags close to the cement factory and represents the deposit of dust, not the typical soil. It can be noticed that samples collected near the TPP in the industrial zone of Tuzla have higher levels of specific activity of all examined natural radioactive nuclides in comparison to other samples. One of the reasons is that samples collected near the TPP are exposed to fly ash released from chimneys. Nearby are the landfills of ash and slag, which also affect the level of radioactivity, since re-suspended dust from the landfill reaches inhabited areas. In samples collected around Lake Modrac, relatively higher values of specific activities were observed. Although there are no industrial activities around, the lake accumulates effluents from industrial facilities. The man-made radioisotope 137 Cs was identified in almost all samples. The specific activity was in the range from (1.0 ± 0.1) to (176 ± 18) Bq kg–1 , with a mean value of 37.1 Bq kg–1 . The highest values, ranging from 106–176 Bq kg–1 were observed in samples collected near the TPP in the community Ši´cki Brod, Tuzla (9,10 and 11) and near the accumulation Lake Modrac (1). This radionuclide originates from nuclear weapons test fall-out and after 1986, mostly from the accident of the nuclear power plant in Chernobyl. The obtained values are in good agreement
Table 3.
Specific activity of natural radioactive nuclides in soil in some European countries [12, 13]. Specific activities of radioactive nuclides (Bq kg−1 )
Country Albania Bulgaria Montenegro Czech Greece Croatia Hungary Macedonia Poland Romania Slovenia World average Present study
238 U
232 Th
226 Ra
40 K
34 (2.5–141) 40 (8–190)
18.3 (0.8–61) 30 (7–160) 23.7 (9–74) 41 (18–168) 28 (1–193) 37 (10–72) 28 (12–45) 25 (19.8–37.9) 24.7 (3.7–86) 38 (11–75) 35 (2–90) 30 (11–64) 32 (7–66)
45 (12–210) 29.3 (7–166) 44 (18–275) 29 (1–310) 43 (18–80) 33 (14–76) 23.4 (0–31.7) 25.2 (4.2–124) 32 (8–60) 41(2–208) 35 (17–60) 32 (6–55)
348 (91–665) 400 (40–800) 246 (78–480) 613 (262–1599) 383 (12–1570) 423 (107–748) 370 (79–570) 456 (0–699) 410 (123–1020) 490 (250–1100) 374 (15–1410) 400 (140–850) 331 (83–546)
45 (10–190) 53 (19–135) 29 (12–66) 36.9 (11.5–92.7) 25.2 (4.2–124) 32 (8–60) 35 (16–110) 41 (8–95)
Downloaded by [New York University] at 13:36 18 May 2015
Isotopes in Environmental and Health Studies
7
with the values in earlier studies for some region of Bosnia and Herzegovina and in neighboring countries [16–19]. According to UNSCEAR the world average values of specific activity for natural radioactive nuclides in soil samples are as follows: 35 Bq kg–1 for 238 U, 30 Bq kg–1 for 232 Th, 35 Bq kg–1 for 226 Ra and 400 Bq kg–1 for 40 K [1]. Our results do not differ significantly from those mentioned above. In Table 3, values from some countries in Europe are listed [1,20]. Based on the measured specific activities of 40 K, 232 Th and 226 Ra in soil samples (Table 2), the gamma absorbed dose rate in air, the annual effective dose, radium equivalent activity, external and internal hazard index were calculated using formulas (2)–(8). These results are shown in Table 4. The gamma absorbed dose rates in air were found to be between 12.1 and 85.4 nGy h–1 , with an arithmetic mean of 47.9 nGy h–1 . The relatively high values of the gamma absorbed dose rates in air were found in samples collected near the Lake Modrac and near the TPP in Ši´cki Brod. According to UNSCEAR, the world average gamma absorbed dose rate in air is 51 nGy h–1 (as calculated) or within the range from 18 to 93 nGy h–1 with a mean value of 57 nGy h–1 (as directly measured) [1]. If the absorbed dose rate is calculated by formula (2), it can be noticed that 137 Cs contributes little to the total dose arising from environmental background and can be neglected. Calculated values of the annual outdoor effective dose on investigated areas are in the range from 0.01 to 0.10 mSv with a mean value of 0.06 mSv, which is comparable with the
Table 4. The gamma absorbed dose rate in air, the annual effective dose, radium equivalent activity, external and internal hazard index. DI Number of sample
Location
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Mean value
LK1 LK2 LK3 LK4 LK5 LK6 LK7 TZ1 TZ2 TZ3 TZ4 TZ5 TZ6 TZ7 TZ8 TZ9 TZ10 TZ11 TZ12 TZ13 TZ14 LK8 LK9 LK10 LK11 LK12 LK13 LK14 LK15 LK16 LK17
DII
Eoutdoor
Eindoor
Raeq
nGyh−1
nGyh−1
mSv
mSv
Bq kg−1
Hex
Hin
53.7 65.1 85.4 71.5 34.5 28.7 18.9 62.8 51.8 49.9 47.6 71.2 59.5 75.1 65.3 69.6 62.3 49.7 65.3 43.5 51.3 12.7 38.2 12.1 27.7 25.7 39.9 35.3 26.9 46.5 36.8 47.9
58.3 68.1 89.2 75.2 34.5 28.6 19.0 66.3 56.6 55.8 52.3 74.6 61.5 77.6 68.2 72.2 64.8 51.1 67.4 44.7 52.7 13.0 39.2 12.4 29.5 26.8 40.7 36.8 27.6 48.1 38.4 50.04
0.07 0.08 0.10 0.09 0.04 0.04 0.02 0.08 0.06 0.06 0.06 0.09 0.07 0.09 0.08 0.09 0.08 0.06 0.08 0.05 0.06 0.02 0.05 0.01 0.03 0.03 0.05 0.04 0.03 0.06 0.05 0.06
0.26 0.32 0.42 0.35 0.17 0.14 0.09 0.31 0.25 0.24 0.23 0.35 0.29 0.37 0.32 0.34 0.31 0.24 0.32 0.21 0.25 0.06 0.19 0.06 0.14 0.13 0.20 0.17 0.13 0.23 0.18 0.23
116.1 143.4 186.3 155.4 74.0 61.4 41.1 134.8 112.1 105.7 101.9 153.8 125.5 160.9 140.5 150.6 134.9 106.5 140.6 92.3 108.6 26.2 81.9 25.6 59.2 55.7 85.1 74.9 57.3 99.8 78.4
0.31 0.39 0.50 0.42 0.20 0.17 0.11 0.36 0.30 0.29 0.28 0.42 0.34 0.43 0.38 0.41 0.36 0.29 0.38 0.25 0.29 0.07 0.22 0.07 0.16 0.15 0.23 0.20 0.15 0.27 0.21
0.41 0.51 0.65 0.55 0.29 0.25 0.16 0.46 0.41 0.39 0.34 0.54 0.43 0.57 0.50 0.52 0.49 0.38 0.50 0.32 0.38 0.09 0.29 0.09 0.21 0.20 0.31 0.26 0.20 0.35 0.26
8
A. Kasumovi´c et al.
world averages [7]. The annual indoor effective doses are in the range from 0.06 to 0.42 mSv with a mean value of 0.23 mSv, which is lower than the world average [1]. The values of Raeq vary from 26.2 to 186.3 Bq kg–1 , which is below the maximum permissible value of 370 Bq kg–1 . The values of the external radiation hazard index, Hex , ranged from 0.07 to 0.50, with an average value of 0.28. The internal radiation hazard index Hin values ranged from 0.09 to 0.65, with an average value of 0.36. These values for all samples studied in this work are less than unity.
4.
Conclusions
The results of activity concentration measurements of natural occurring radioactive nuclides U, 235 U, 232 Th, 226 Ra and 40 K in soil samples from the area of the cities Tuzla and Lukavac, Bosnia and Herzegovina are presented. Soil sampling locations were chosen near the industrial areas of these cities in order to determine the influence of industry on the natural radioactivity in this region. The results show that relatively higher values of specific activity of measured radioactive nuclides in comparison to other samples are present in soil samples collected in the vicinity of the coal TPP in the industrial zone of Tuzla as well as nearby the accumulating Lake Modrac. Presented results do not differ significantly from the world average ones. In general, it can be noticed that results do not show the enhancement of natural radiation background in the vicinity of investigated industrial facilities. The calculated value of the gamma absorbed dose rate in air varies from 12.1 to 85.4 nGy h–1 , with an average of 47.9 nGy h–1 . The estimated value of the annual outdoor effective dose is in the range from 0.01 to 0.10 mSv with a mean value of 0.06 mSv, what falls within the range of the world average. The estimated value of the annual indoor effective dose also falls within the range of the world average.
Downloaded by [New York University] at 13:36 18 May 2015
238
Disclosure statement No potential conflict of interest was reported by the authors. References [1] UNSCEAR. Report to the General Assembly, with scientific annexes, Sources and effects of ionizing radiation. New York: United Nations Scientific Committee on the Effects of Atomic Radiation; 2000. [2] Offical Web Page of Tuzla Canton. Economy of Tuzla Canton. [Internet] 2010. [cited 2013 Feb 1]. Available from: http://vladatk.kim.ba/OKantonu/privreda.htm. Bosnian. [3] Mondal T, Sengupta D, Mandal A. Natural radioactivity of ash and coal in major thermal power plants of West Bengal, India. Curr Sci India. 2006;91:1387–1393. [4] Papp Z, Dezs˝o Z, Daróczy S. Significant radioactive contamination of soil around a coal-fired thermal power plant. J Environ Radioactiv. 2002;59:191–205. [5] Adrovic F, Proki´c M, Ninkovi´c MM, Glisi´c R. Measurements of environmental background radiation at location of coal-fired power plants. Radiat Prot Dosim. 2004;112:439–442. [6] Ebaid YY. Use of gamma-ray spectrometry for uranium isotopic analysis in environmental samples. Rom J Phys. 2010;55:69–74. ˇ [7] Slivka J, Bikit I, Veskovi´c M, Conki´ c Lj. Gamma-spectrometry, special methods and applications. Serbia: University of Novi Sad; 2001. Serbian. [8] Gilmore G. Practical gamma-ray spectrometry. 2nd edition. West Sussex, England: John Wiley & Sons, Ltd.; 2008. Chapter 16, Gamma spectrometry of naturally occurring radioactive materials (NORM); p. 316–328. [9] Diab HM, Nouh SA, Hamdy A, El-Fiki SA. Evaluation of natural radioactivity in a cultivated area around a fertilizer factory. J Nucl Radiat. 2008;3:53–62. ´ [10] Dołha´nczuk-Sródka A. Estimation of external gamma radiation dose in the area of Bory Stobrawskie forests (PL). Environ Monit Assess. 2012;184:5773–5779. [11] Hafezi S, Amidi J, Attarilar A. Concentration of natural radionuclides in soil and assessment of external exposure to the public in Tehran, Iran. J Radiat Res. 2005;3:85–88.
Downloaded by [New York University] at 13:36 18 May 2015
Isotopes in Environmental and Health Studies
9
[12] Almayahi BA, Tajuddin AA, Jaafar MS. Radiation hazard indices of soil and water samples in Northern Malaysian Peninsula. Appl Radiat Isot. 2012;70:2652–2660. [13] Jabbar A, Arshed W, Bhatti AS, Ahmad SS, Akhter P, Rehman SU, Anjum MI. Measurement of soil radioactivity levels and radiation hazard assessment in southern Rechna interfluvial region, Pakistan. Environ Monit Assess. 2010;169:429–438. [14] Institute for Public Health FB&H. Radioaktivnost u životnoj sredini Federacije Bosne i Hercegovine za 2012. godinu [Radioactivity in environment of the Federation of Bosnia and Herzegovina in 2012]. Sarajevo; 2013. Bosnian. [15] Institute for Public Health FB&H. Radioaktivnost u životnoj sredini Federacije Bosne i Hercegovine za 2013. godinu [Radioactivity in environment of the Federation of Bosnia and Herzegovina in 2012]. Sarajevo; 2014. Bosnian. [16] Huremovi´c J, Horvat M, Ruždi´c E, Ja´cimovi´c R. Istraživanje radiokontaminacije grada Sarajeva i njegove okolice s obzirom na radionuklide [Analysis of the radiopollution of the City of Sarajevo and its surrounding area with regard to radionuclides]. Kem Ind. 2009;58:165–170. Croatian. [17] Jankovi´c MM, Todorovi´c DJ, Savanovi´c MB, Nikoli´c SM, Vocki´c ND. Radioactivity of the soil in Republic of Srpska. In: Proceedings of the French–Serbian European summer university: Renewable energy sources and environment–multidisciplinary aspect; 2006 Oct 17–24; Vrnjacka banja, Serbia. p. 169–172. [18] Jankovic M, Todorovic D, Savanovic M. Radioactivity measurements in soil samples collected in the Republic of Srpska. Radiat Meas. 2008;43:1448–1452. [19] Deljki´c D, Vidic A, Mari´c S, Ili´c Z, Sirko D. Radioactivity of the soil in Federation Bosnia and Herzegovina. In: Garaj-Vrhovac, V, Kopjar, N, Miljanic, S, editors. Proceedings of the Sixth Symposium of the Croatian Radiation Protection Association; 2005 Apr 18–20; Stubicke Toplice, Croatia. p. 358–362. [20] UNSCEAR. Report to the general assembly, with scientific annexes, sources and effects of ionizing radiation. New York: United Nations Scientific Committee on the Effects of Atomic Radiation; 2008.
