Radiation Protection and Environment

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 42  |  Issue : 1  |  Page : 10--14

Measurement of radon gas activity concentrations in drinking water in the city center of Adıyaman, Turkey


Mehmet Fatih Aydin1, Ömer Söǧüt2,  
1 Department of Electrical and Energy, Technical Sciences Vocational School, Adiyaman University, Adıyaman, Turkey
2 Department of Physics, Faculty of Science and Letters, Kahramanmaras Sutcu Imam University, Kahramanmaras, Turkey

Correspondence Address:
Mehmet Fatih Aydin
Department of Electrical and Energy, Technical Sciences Vocational School, Adıyaman University, Adıyaman 02040
Turkey

Abstract

In this study, 16 water samples collected from homes and the water tanks in various districts from two different natural water sources, supplying Adıyaman's domestic drinking water. Measurements of radon gas activity concentrations in collected samples have been performed by AlphaGUARD PQ2000 PRO radon detector. The average radon (222Rn) activity concentrations of samples taken from the natural water resources and homes were found to be 0.39 ± 0.11 and 0.51 ± 0.14 Bq/L, respectively. In addition, the annual effective dose equivalent that exposed due to radon gas in drinking water is also calculated and found to be 1.30 ± 0.36 μSv/y. The upper limit for radon gas activity concentrations in drinking waters has been defined by the United States Environmental Protection Agency (USEPA), United Nations Scientific Committee on the Effects of Atomic Radiation, and World Health Organization to be 11, 40, and 100 Bq/L, respectively. The measured values of radon gas activity concentrations are lower than that of limit value defined by the USEPA.



How to cite this article:
Aydin MF, Söǧüt &. Measurement of radon gas activity concentrations in drinking water in the city center of Adıyaman, Turkey.Radiat Prot Environ 2019;42:10-14


How to cite this URL:
Aydin MF, Söǧüt &. Measurement of radon gas activity concentrations in drinking water in the city center of Adıyaman, Turkey. Radiat Prot Environ [serial online] 2019 [cited 2019 Aug 18 ];42:10-14
Available from: http://www.rpe.org.in/text.asp?2019/42/1/10/259669


Full Text



 Introduction



Radon is a natural radioactive gas which has no odor, color, or taste. Therefore, it can only be detected with special equipment. Radon is one of the most radioactive and toxic gases. According to the International Commission on Radiological Protection, 40%–75% of exposure of human by natural radioactive sources comes from radon and its daughter nucleus. Radon is a known carcinogenic agent, and being viewed by the World Health Organization (WHO) as the leading reason of lung cancer after smoking.[1]Radon is the main risk factor among the nonsmokers.[2] Meanwhile, very high level of radon in drinking water can be a significant risk of the gastrointestinal and stomach cancer.[3] In addition, the radon in drinking water is associated with stomach cancer, contributing up to 30 deaths per year.[4] The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)[5] reports that about 50% of the annual effective dose received by people living in radiation background areas of the world is contributed from the inhalation of 222Rn and its progeny.[6] Prolonged inhalation of radon gas may lead to the increasing of the dose of radiation in the respiratory system and the deterioration of the structure of the sensitive inner tissue of the lung. As a result, it will also increase the risk of lung cancer. Therefore, the effects on the human health of radon gas must be considered. An important property of radon is its solubility in water. Dissolved radon releases to air upon the usage of water, which adds to the dose received from inhalation of airborne radon emanating from the ground itself.[7] When radon gas decays, it gives rise to isotopes of solid elements such as Pb, Bi, and Po. These short-life decay products are also radioactive, and they attach themselves to natural aerosol particles in the atmosphere.[8] Decay products (which are attached to particles) and unattached decay products may be inhaled. Then, they may stick to walls of the lungs and other parts of the respiratory system. Since these radon decay products undergo further decay, they emit alpha-particles, which irradiate cells on the wall of the respiratory system.[9] The radon travels to long distances by water. In the process of radioactive decay of 226Ra, escaping radon nucleus is being released into water, and hence, underground waters may contain significant concentrations of radon. A significant contribution to the exposure to radon and its decay products comes from ingested drinking water from underground sources, excavated and drilled wells.[10]

In this study, one reason for making the radon gas measurements in drinking water in Adıyaman city center is that the radon gas is dangerous for human health. For this reason, the radon gas activity concentration measurements in drinking water in Adıyaman city center were made and the obtained values compared with the limit values in the literature. Another more important reason for the measurements is to determine the level of the radon gas background level in drinking water in Adiyaman city center. As mentioned above, the radon gas is dangerous for human health, and the concentration of radon gas activity to which people are exposed should be determined precisely in the areas of public life.

The aim of this survey is to determine radon gas activity concentrations in drinking water in the city center of Adıyaman in Turkey. In addition, we have also calculated annual effective dose equivalent for living people in Adıyaman city center.

 Materials and Methods



Description of study area

Adıyaman is a city located in the Southeastern Anatolia region of Turkey. It is located on 38°11'–37°25' north latitude with 39°14'–37°31' east longitude. Cities located at the East, South, West, and North of Adıyaman are Diyarbakır, Gaziantep and Şanlıurfa, Kahramanmaraş, and Malatya, respectively. The water samples were taken from Havşerin and Gürlevik water resources providing domestic water to Adıyaman city, from the main water tank of the city center, from taps in homes, from street fountains, and from nearly 2000-year historical Roman fountain which is still used by the people in Ören district today. The water sampling locations were shown in [Figure 1].{Figure 1}

Taking samples and preparing

A total of 16 water samples from the study area in the manner that represents the region have been taken. The water samples have been collected following by drained out for a 5-min period. After washing the bottles with water, they have been filled under a stream of water in manner that there is no gap to the brim to prevent leak out of the radon gas. The collected water samples were placed in polyethylene bottles of 500 mL and 1500 mL which were presterilized and labeled.

Instrumentation and calibration

AlphaGUARD PQ2000 PRO detector was used for the measurement of radon gas activity concentrations. This detector can also simultaneously measure three different climatic parameters such as atmospheric pressure, temperature, and humidity. However, the radiation measurements in air, water, and building materials can be made using AlphaGUARD PQ2000 PRO radon gas detector. Since the radon within water is driven by air within the detector assembly and air is also contributed to this value, the value of radon gas activity concentration measured in the detector did not show a real concentration in the sample.

In this study, before starting each measurement, a background measurement was made for 10 min. After the water sample was poured carefully into the degassing tube and the system was turned on. The measurement of radon gas lasted for 30 min. After the first 10 min the pump was switched off and the AlphaGUARD detector measured the activity for the remaining 20 min. The performance level of the pump had an air flow rate of 0.3 L/min.

The systems consist of a pump, a tube. The advantage of this system is that it is calibrated by the manufacturer and provided a 5-year warranty.

The schematic appearance of the measurement system of the radon gas activity concentration is given in [Figure 2].[11]{Figure 2}

Activity measurements and calculations

The radon gas activity concentrations in the water samples were calculated by the following equation.[11]

[INLINE:1]

Where, Cwater is the radon gas activity concentration of the water sample (Bq/L), CAir is the radon concentration (Bq/m3) in the measuring setup after expelling the radon (indicated by AlphaGUARD), C0 is the radon concentration in measured setup before sampling (Bq/m3), Vsystem is the internal volume of the measurement system (mL), Vsample is water sample volume (mL), and K is the radon diffusion coefficient. The radon diffusion coefficient (K) shows the changes depending on the temperature, and it decreases with increasing temperature. If the temperature of radon gas increases, the passing speed from the liquid phase to the gas phase increases. For this reason, K is defined as concentration value in liquid phase/concentration value in gas phase. K was calculated using average temperature during the measurement with the following formula.

K = 0.105 + 0.405 e−0.502T(°C)

 Results and Discussion



In this study, the radon (222Rn) gas activity concentrations of drinking water samples taken from house taps, from street fountains, and from Havşerin and Gürlevik water sources, which are the main water sources providing drinking water to Adıyaman city, were measured using the AlphaGUARD PQ2000 PRO. In addition, the annual effective dose equivalent of radon gas activity concentration was calculated for people living in Adıyaman province center. The values of radon gas activity concentrations measured in total 16 water samples taken from the taps of the houses in neighborhood and from natural water resources (Havşerin and Gürlevik) providing water to Adıyaman city are given in [Table 1] and [Table 2], respectively.{Table 1}{Table 2}

The average radon gas (222Rn) activity concentration of water samples taken from the neighborhood and from natural water sources was calculated as 0.39 ± 0.11 and 0.51 ± 0.14 Bq/L, respectively. As seen from [Figure 3], the measured radon gas activity concentration in Gürlevik water source is higher than that of measured in Havşerin water source. The reason of this may be the soil and rock structure where Gürlevik water source emerges. As seen from [Figure 4], among the water samples taken from neighborhoods, while the value of the largest radon gas activity concentration was measured in the water sample taken from Kayalık neighborhood, the value of the smallest radon gaseous activity concentration was measured in the water sample taken from Fatih neighborhood.{Figure 3}{Figure 4}

The radon taken by drinking water has a dose contribution to the body and organs. The dose contribution to the body due to the radon gas taken by drinking water was calculated by Dw equation (DW= CW× CRW× DCW).[12] In a report issued by the UNSCEAR,[5],[13] the dose conversion factor for radon has been calculated to be 3.5 nSv/Bq. In this calculation, the average digestion of drinking water and the daily water consumption of an adult individual have been assumed to be 2 L, and annual consumption has been taken as 730 L/y. In the Dw equation, DW is the amount of the calculated the annual effective dose, CW is radon concentration (kBq/m3), CRW is the estimated amount of digestion of the water, and DCW is dose conversion factor. While the average radon gas activity concentration of water samples taken from the natural water resources (Havşerin and Gürlevik) providing domestic water of Adıyaman city is calculated as 0.51 ± 0.14 Bq/L, the annual effective dose equivalent is computed as 10.30 ± 0.36 μSv/y. While the upper limit for radon gas in the drinking water was defined as 100 Bq/L by the WHO,[14],[15] it was defined as 40 Bq/L by the UNSCEAR[16] and has been defined as 11 Bq/L by the United States Environmental Protection Agency (USEPA).[17]

The obtained results were much smaller than 11 Bq/L limit values given by the USEPA.[17] The radon in water characteristically adds only a small amount to the indoor air concentration. For instance, radon at a given concentration in water adds about 1/10,000 as much to the air concentration. Therefore, the measurement of radon gas in drinking water is very important. There is always radon in the air by the penetration of soil gas into homes. Therefore, very high concentrations of radon in water will make an important contribution to the particle concentration in the air.[18]

 Conclusions



The water samples were taken from Havşerin and Gürlevik water sources providing the domestic drinking water to the city of Adıyaman, from main water reservoir of the city center, and from the taps in the houses. The annual effective dose equivalent for radon gas in drinking water was measured as 1.30 ± 0.36 μSv/y. The calculated maximum value of annual effective dose from 222Rn ingested with water is much below the recommended value of 0.1 mSv for the public.[14],[19] The values of the measured radon gaseous activity concentrations in the water samples are lower than the limit values given by the USEPA,[17] WHO,[14] and UNSCEAR.[16] However, the radon and its short-lived decay products in the environment play the most important role to human exposure from natural sources of radiation. In addition, according to the WHO, in many countries, the radon gas is the second of the reasons of lung cancer after smoking.[20] The epidemiological searches have supplied persuasive evidence of an association between indoor air radon gas exposure and lung cancer, even at the relatively low radon levels commonly found in residential buildings. Moreover, the radon gas was classified as a human carcinogen in 1988 by the International Agency for Research on Cancer that is specialized cancer research agency of the WHO.[21]

Financial support and sponsorship

This work is supported by Scientific Research Fund of Kahramanmaraş Sütçü Imam University, Turkey (project No. 2013/3-29D YLS), and all the authors wish to thank for this support.

Conflicts of interest

There are no conflicts of interest.

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