Chemosphere 225 (2019) 859e870
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Chemosphere
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Natural radioactivity in urban soils of mining centers in Armenia: Dose rate and risk assessment
* Olga Belyaeva a, , Konstantin Pyuskyulyan a, b, Nona Movsisyan a, Armen Saghatelyan a, Fernando P. Carvalho c a Center for Ecological-Noosphere Studies (CENS) of NAS RA, 68 Abovyan Street, 0025 Yerevan, Armenia b Armenian Nuclear Power Plant, 0911 Metsamor, Armavir Marz, Armenia c Laboratorio de Protecçao~ e Segurança Radiologica, Instituto Superior T ecnico/Campus Tecnologico Nuclear, Universidade de Lisboa, Estrada Nacional 10, km 139,7, 2695-066 Bobadela LRS, Portugal highlights
Soil radioactivity enheancemet was studied based on urban geochemical survey. Copper and polymetallic mining is the factor for natural radioactivity enheancement. Mining legacy sites located at high altitudes preovoke NORM accumulation in vales. Enhanced soil radioactivity due to metal mining is not risk factor to human health. article info abstract
Article history: Soil radioactivity levels, dose rate and radiological health risk were assessed in metal mining centers of Received 10 December 2018 Armenia, at the towns of Kapan and Kajaran. Archive soil samples of the multipurpose soil surveys Received in revised form implemented in Kapan and Kajaran were used for estimation of total alpha and total beta activity levels 4 March 2019 using gas-less iMatic™ alpha/beta cօunting system (Canberra). Ten representative soil samples per town Accepted 10 March 2019 were randomly selected from different urban zones for naturally occurring radionuclide measurements Available online 11 March 2019 (238U, 232Th, 40 K) using high purity germanium detector. Four radiological indices: radium equivalent Handling Editor: Martine Leermakers activity, outdoor absorbed dose rate, annual effective dose equivalent and excess lifetime cancer risk were estimated based on naturally occurring radionuclide activity concentrations in soils. Results suggest Keywords: that in Kapan the soil radioactivity, although enhanced by copper and gold-polymetallic mining, are not a Metal mining significant risk factor to human health. In Kajaran, the soil radioactivity levels were above the back- Total alpha/beta activity ground and world average values provided by UNSCEAR, but radionuclides originated in a natural Naturally occurring radioactive materials geogenic source and not from mining activities. Generally, in this region no significant radiological risks (NORM) were identified in relationship with molybdenum, copper, and gold-polymetallic ore mining. Dose rate © 2019 Elsevier Ltd. All rights reserved. Cancer risk
1. Introduction Paschoa and Steinhausler,€ 2010), coal mining and combustion (Papastefanou, 2010), production of some building materials The phenomenon of technologically enhancement of natural (Paschoa and Steinhausler,€ 2010; Pavlidou et al., 2006). radioactivity has been investigated since from the 1970s (IAEA, Metal mining may act also as factor in the enhancement of 2013; UNSCEAR, 2010, 2000). The most investigated technologi- environmental radioactivity due to mobilization of naturally cally enhanced natural radioactivity related issues are oil and gas occurring radioactive isotopes contained in the metal ores production (Al Nabhani et al., 2016), phosphate rock mining and (Borysenko et al., 2014; Carvalho, 2017; UNSCEAR, 2010, 2000). The phosphogypsum application in agriculture (Canovas et al., 2018; most abundant natural radionuclides are the progeny of uranium (238U) and thorium (232Th), of the natural radioactive decay series, and the radioactive potassium (40K) (UNSCEAR, 2010). In most ores mined for stable metals the content of co-occurring uranium and * Corresponding author. Tel.: þ374 10 572924. E-mail address: [email protected] (O. Belyaeva). thorium does not exceed the average content of the upper https://doi.org/10.1016/j.chemosphere.2019.03.057 0045-6535/© 2019 Elsevier Ltd. All rights reserved. 860 O. Belyaeva et al. / Chemosphere 225 (2019) 859e870
continental crust, i.e., 36 and 44 Bq kg 1, respectively (Paschoa and Euratom calls upon studies for identification and assessment of Steinhausler,€ 2010) and the radioactive 40K isotope makes 0.012% of naturally occurring radioactive materials (NORM) and industries the naturally occurring potassium (Baskaran, 2012). With the processing NORM in order to enhance radiation protection of typical activity concentration as 820 Bq kg 1 in continental crust humans (European Parliament, 2014). (Paschoa and Steinhausler,€ 2010). Because of the low content of Some regions of Armenia are old mining centers with current naturally occurring radionuclies in metal ores, the radiological and legacy mining and milling waste and suffering with pollution impact of non-uranium metal mining is often not considered in the and long lasting environmental impacts of several types that could evaluation of environmental impacts and in pollution surveys, and not be remediated up to the present time. Impact of this mining often no radiological risk assessment is performed for these mines legacy on environmental contamination, human exposure and (Chambers et al., 2011; IAEA, 2006). However, in some cases the public health remained uncovered for long time and it is of much enhancement of environmental radioactivity levels from non- societal concern (Pipoyan et al., 2018; Saghatelyan et al., 2008; uranium metal mining is enough to exceed radiation dose limits Sahakyan et al., 2015; Tepanosyan et al., 2018; Volfson et al., and hence pose a significant environmental and health concern 2010). Furthermore, economic development and future of entire (Carvalho, 2017; Carvalho et al., 2014; Guagliardi et al., 2016; Reddy mining sector may depend upon the evaluation of mining impacts, et al., 2017; Saghatchi et al., 2010; UNSCEAR, 2010, 2000). In such integrated strategic assessment, and decision making process cases, although originated from naturally occurring radionuclides, (International Bank for Reconstruction and Development /The the long-term exposure to ionizing radiation may result in harmful World Bank, 2014; Stefes and Weingartner, 2015). health effects, such as chronic lung diseases, anemia, different types The aim of this study was to perform the evaluation of radio- of solid cancer, and leukemia (UNSCEAR, 2000). A number of non- activity levels in urban soils and carry out a dose rate assessment nuclear industries with occurrence and enhancement of radiation and life time cancer risk evaluation in the biggest mining centers of exposure to naturally occurring radioactive materials arenowadays Armenia, i.e., at the metal mining towns of Kapan and Kajaran. receiving increasing scientific and regulatory attention (IAEA, Results for NORM in these polymetallic mining areas are presented 2013). For example, the recent European Union Directive 59/2013/ for the first time and are of relevance for the entire region and for
Fig. 1. Location of towns of Kapan and Kajaran and geological map of the studied region. O. Belyaeva et al. / Chemosphere 225 (2019) 859e870 861 the future monitoring of mining centers. the southeastern slopes of the Zangezur Range (N 39 120 and E 46 240), on the banks of the middle course of river Voghji, and at 2. Materials and methods the average height of 910 m above sea level. The geological struc- ture of this area (Fig. 1) is featured by strongly dissected Jurassic 2.1. Description of study area volcanic (basalt, andesite) and sedimentary (breccia, limestone, dolomite and clay slate) formations, with subvolcanic rocks sub- The town of Kapan is the regional center of Syunik Marz ordinated. Copper-polymetallic ore bodies are represented by veins (province), with 39024 permanent residents. This town is located at (more than 450) and 14 stockwork. Copper content in veine and
Fig. 2. Location of mining infrastructure in Kapan and Kajaran. 862 O. Belyaeva et al. / Chemosphere 225 (2019) 859e870 stockworks ores vary within 12e17%, and 0.5e4.6% respectively. In “Kapan copper-pyrite” and the “Shahumyan gold-polymetallic” addition to copper, native Au and Ag, and Zn are of practical interest deposits both through underground mines. The copper ore pro- as well (Ayvazyan et al., 2006; Mederer et al., 2014). cessing plant, performing ore crushing, milling, and flotation op- The climate is moderately warm, with cold winters (the average erations is located within the town borders (Mederer et al., 2014). temperature in January varies from 3 Cto 4 C, with an absolute Furthermore, several abandoned waste-rock piles from mine minimum of 30 C and a snow cover is formed every year) and workings are scattered through Kapan area, and an abandoned warm summers (in JulyeAugust the average temperature varies quarry is located at the north of the town. Tailings from the copper from þ19 Ctoþ21 С with the absolute maximum of þ35 С). The ore processing plant are dumped in the Geghanush tailing dump annual rainfall is around 500e600 mm (Ayvazyan et al., 2006). located within the urban area at the southern part of the town The exploitation of polymetallic deposits in Kapan area started (Fig. 2). Another operating tailing dump, Artsvanik, is situated near in 1846. Currently, two metal deposits are mined in this area, the Kapan but is geographically separated from the urban area by a
Fig. 3. Sampling locations of urban soil surveys of Kapan and Kajaran.
Table 1 Descriptive statistics of total alpha and total beta activities of urban soils and background activity values in soils from control sites.
Statistics Kapan Kajaran
Total alpha activity Total beta activity Total alpha activity Log-transformed total alpha activity Total beta activity
Valid N 49 146 50 50 50 Excludeda 96 0 0 0 0 Minimum <14 73.0 3.5 0.5 18.2 Maximum 45.5 581.0 60.3 1.8 607.0 Mean e 228.1 21.2 1.2 363.7 Median e 231.0 20.0 1.3 373.5 Std. Deviation e 69.0 13.6 0.3 107.2 Coefficient of variation e 0.3 0.64 0.3 0.29 Skewness e 0.8 0.9 0.8 0.6 Standard Error of Skewness e 0.2 0.3 0.3 0.3 Kurtosis e 4.1 0.8 0.0 1.4 Standard Error of Kurtosis e 0.4 0.7 0.7 0.7 Background <0.014 180 23.85 e 350
a Lower than MDA; “e” not available. O. Belyaeva et al. / Chemosphere 225 (2019) 859e870 863 minor spur of the Zangezur Ridge (Ayvazyan et al., 2006; Sahakyan recorded in January, 30 C, and the absolute temperature et al., 2015; Volfson et al., 2010). maximum in JulyeAugust, þ35 C. The average annual rainfall is The town of Kajaran is a typical industrial community with 6916 650 mm (Ayvazyan et al., 2006). permanent residents. The town is located on the eastern slope of The development of Kajaran metal deposits was started in the the Zangezur Range, in the upper catchment basin of river Voghji (N 1950s and, nowadays, Kajaran is a modern mining center. The 39 90 and E 46 90) and is at the average height of 1950 m above sea copper-molybdenum deposit, exploited as an open-pit mine, and level. The geological structure of this area features mainly Tertiary the “Zangezur Copper Molybdenum Combine e ZCMC” (Fig. 2), volcanogenic and intrusive rocks: monzonites and porphyritic performing ore crushing, grinding and froth flotation operations granites-granodiorites (Fig. 1)(Saghatelyan et al., 2008). Kajaran are both situated on the western limit of the town (Ayvazyan et al., sulfide copper-molybdenum deposit timed to monzonites, which 2006). The tailings from ZCMC ore processing plant are transported are strongly altered by hydrothermal processes. The main minerals into the Artsvanik tailing dump located near the town of Kapan of the Kajaran deposit are molybdenite and chalcopyrite. Subordi- (Mederer et al., 2014; Saghatelyan et al., 2008). nated minerals are pyrite, magnetite, hematite, sphalerite, as well as native tellurium and gold. In addition, ore contains rhenium, 2.2. Soil sampling, pretreatment and analysis selenium and silver (Saghatelyan et al., 2008; Tepanosyan et al., 2018). Archive samples from multipurpose urban geochemical soil The climate is temperate-mountainous, with short cool sum- surveys of Kapan (Scale 1:25000) and Kajaran (Scale 1:10000) mers and cold winters. The absolute temperature minimum was carried out previously, in 2007 and 2005 respectively, were used for
Fig. 4. Histograms, boxplots and normal Q-Q plots of total alpha and total beta activities in soils from Kapan and Kajaran. 864 O. Belyaeva et al. / Chemosphere 225 (2019) 859e870 this study. In Kapan and Kajaran were collected 143 and 50 soil samples from selected control sites, mixing them thoroughly in a samples, respectively. Within the frames of this study, all of archive pooled sample, and then taking an aliquot for total alpha and total samples were counted for total alpha and beta activities. Based on beta counting. that results ten samples per town (9 urban soil samples and 1 For radionuclide identification and determination of radionu- pooled background sample) was selected for radionuclides mea- clide activity concentration by gamma spectrometry, ten repre- surement. In order to avoid human error, the random generator tool sentative soil samples per town were randomly selected from three of ArcMap 10.3 software was applied for selection of samples. The urban functional zones: 1) public gardens and urban agriculture location of soil sampling stations sites in the territories of the towns sites, 2) residential areas, and 3) industrial areas. From archived of Kapan and Kajaran are presented in Fig. 3. These soil surveys samples, 700 g of air-dried, mixed, and sieved (>2 mm mesh) soil were designed and implemented using relevant international sample material was packed in 900 ml capacity Marinelli plastic guidelines (Cochran, 1977; Wilson and Artiola, 2002), and US EPA beakers, sealed, and held in storage for at least two weeks in order (Simmons et al., 2014; US EPA, 2002, 1994) standards. Soils were to allow formation of radioactive equilibrium between radium, sampled in different functional zones of the urban area, namely in radon and their short-lived radioactive progeny. A high purity urban agricultural sites, public gardens, residential and industrial germanium detector (HpGe) with energy resolution of 1.8 keV zones of the towns. Undisturbed soils were sampled for the upper FWHM (for the 1332 keV g-ray energy line from 60Co), coupled to a soil layer (0e10 cm depth) with an hand shovel. At each sampling DSA-1000 multichannel analyzer (CANBERRA), was used in the station, marked with GPS coordinates, 3e5 samples were collected determination of radionuclides. Efficiency calibration was per- inside an area of 10 10 m centered in the GPS point, and pooled formed using Labоratоry Sоurceless Calibration Sоftware (LabSOCS) and mixed in order to obtain a representative sample. by CANBERRA which allows eliminating the necessity of a standard Once in the laboratory, soil samples were air dried, dis- sоurce fоrefficiency calibratiоn(CANBERRA, 2004). Еnergies of aggregated, and sieved (<2 mm) according to ISO-11464 (ISO, 105.3 keV of Eu-155 and 1275 keV of Na-22 were used as the 2006), and then stored in sealed plastic containers until analysis. reference for gamma spectra peak energies measurement. Spec- In order to determine background activity concentrations of trum acquisition and analysis were performed in Genie 2000 radionuclides in soils, control sites were selected for each town also software. Participation in national interlaboratory comparison in the framework of the urban geochemical surveys (Saghatelyan program allows quality control ensuring. Laboratory replicate soil et al., 2010; Tepanosyan et al., 2018; Volfson et al., 2010). The samples were measured repeatedly as part of quality control selected control sites, or background sites, have the same paedo- measures. geological nature as the studied urban territories and have been The gamma spectrum acquisition time was 15000 s. After cor- subjected to minimal anthropogenic impact. Selected control sites recting for background and Compton contribution, the activity were located at a distance of 3 km to the north from Kapan and at concentrations of 226Ra (186.0 keV), 214Pb (351.9 keV), 214Bi 5 km to the south-east from Kajaran. These control sites are sepa- (609.2 keV); 212Pb (239.0 keV), 212Bi (727.0 keV) and 40K rated from town areas by Zangezur Ridge mountains, and thus (1460.0 keV) were determined. The 238U and 232Th were calculated located in different valleys. Pollutants from mining are not likely to from the activity of their decay products: 238Uby226Ra, 214Pb and have reached, by wind or water transportation, these control sites. 214Bi; 232Th by 212Pb and 212Bi. Seven and five undisturbed soil samples were collected from the contol sites of Kapan and Kajaran, respectively. The methodological approach used for selecting these control sites is described in more detail elsewhere (Tepanosyan et al., 2017). For total alpha and total beta activity measurement 1 g of previously air-dried, mixed and sieved (<2 mm) material of each soil sample, was taken and further homogenized in an agate mortar. From this homogenized soil material, an aliquot of 0.5e0.7 g was transferred and accurately weighted in a round plastic cuvette (D ¼ 6 cm and 1 mm deep) that is the standard sampler holder for the radioactivity counting equipment. The thickness of soil layer in the sample holder was around 0.1e0.2 mm, minimizing self-absorption in the sample. Each soil sample was counted for determination of total alpha and total beta activities using the low background gas-less Alpha/ Beta Counting System iMatic equipped with solid state silicon PIPS detector (CANBERRA). The system was calibrated with a beta 90Sr/90Y and an alpha 241Am standard sources from CANBERRA. Radioactive standard sources have the same diameter as the envi- ronmental samples. The counting efficiency determined with the radioactive standards was 32.96 ± 1.01% for alpha activity and 64.30 ± 3.87% for beta activity. The radioactive background was measured once a week using a clean sample holder with no sample. The counting time used for sample counting was 12000 s, and the Minimum Detectable Activity (MDA) in such conditions was determined at 14.0 and 7.0 Bq kg 1 for total alpha and total beta activity, respectively. In order to measure the total alpha and total beta activity in soils from control sites for determination of the natural radioactive background to be used as a control level, a pooled soil sample from the control site was used for each town. This background soil Fig. 5. Distribution of total alpha and total beta activities in soils from Kapan (top) and sample was prepared by taking similar portions of archived soil Kajaran (bottom). O. Belyaeva et al. / Chemosphere 225 (2019) 859e870 865
In order to determine radionuclide activity concentrations in For visualization of the spatial distribution of soil total beta control areas, for collation with potentially impacted urban areas, a activity levels the ArcGIS software (version 10.3) was used. The pooled background soil sample was used for each town. This Inverse Distance Weighting (IDW) method was applied for inter- background soil sample was prepared by taking similar portions of polation and overall spatial pattern revelation. archived soil samples from selected control sites for each town, mixing them thoroughly in a pooled sample, and then taking an aliquot for gamma spectrometry in a similar manner as done for 2.4. Calculation of radiological hazard and health risk indices total alpha/beta counting procedure. In order to quantify the radiation hazard for human population due to radionuclides in top soils, four radiological indices are 2.3. Statistical analysis and mapping required and were calculated. These indices are the radium equivalent activity (RaEq), the Outdoor gamma absorbed dose rate The statistical treatment of data was performed using IBM SPSS (ODRA), the Annual effective dose equivalent (AEDE), and the Excess software. Descriptive statistics of total alpha and total beta activ- lifetime cancer risk (ELCR). ities and activity concentrations of radionuclides were calculated. The Radium equivalent activity (RaEq) represents a weighted In order to estimate the statistical distribution of total alpha and sum of the activities of 238U, 232Th and 40K and takes also into ac- total beta activities Shapiro-Wilk test was performed and histo- count the radiation hazards associated with them. It was estimated grams, Q-Q plots, and box-plots were made. using the relation (UNSCEAR, 2000)։ The small size of the sample used (n ¼ 10 per a town) for ¼ þ : þ : determining activity concentrations of natural radionuclides do not RaEq CU 1 43CTh 0 077CK allow performing the normality test. Therefore, for correlation 1 analysis between radionuclides activity concentration and total where CU,CTh and CK are the activity concentration in Bq kg of alpha and total beta activities, the non-parametric (distribution 238U, 232Th and 40K respectively. It is assumed that 370 Bq kg 1 of free) Spearman rank correlation method was applied (Reimann 238U, 259 Bq kg 1 of 232Th and 4810 Bq kg 1 of 40K produce the et al., 2008)․ same gamma ray dose rate (UNSCEAR, 2000)․
Fig. 6. Distribution of total alpha and total beta activities in soils from Kapan (top) and Kajaran (bottom). 866 O. Belyaeva et al. / Chemosphere 225 (2019) 859e870
Table 2 Activity concentrations of naturally occurring radionuclides in selected soil samples of Kapan and Kajaran.
Sample code Description Activity concentrations (Bq kg 1)
40K 238U 232Th RaEq
Kapan Pooled sample Control site 380.4 ± 37.3 33.8 ± 1.2 11.4 ± 1.2 79.3 KF-79-s Public garden, urban soil 267.0 ± 27.1 29.0 ± 2.2 16.0 ± 1.5 72.4 KF-97-s Public garden, urban soil 518.5 ± 52.2 23.5 ± 3.0 29.3 ± 2.2 105.4 KF-115-s Residential part, urban soil 170.6 ± 17.9 13.8 ± 1.2 7.0 ± 1.0 36.9 KF-35-s Residential part, urban soil 308.1 ± 31.0 16.4 ± 1.4 18.4 ± 1.1 66.5 KF-53-s Residential part, urban soil 113.0 ± 11.5 42.0 ± 3.2 24.0 ± 2.2 85.0 KF-128-s Residential part, urban soil 130.0 ± 13.2 44.0 ± 3.4 28.0 ± 2.5 94.1 KF-29-s Town border, adjacent soil 263.9 ± 27.1 37.7 ± 1.8 18.2 ± 1.2 84.1 KF-20-s Shahumyan mine, adjacent soil 598.0 ± 60.6 61.0 ± 4.7 22.5 ± 2.0 139.2 KF-119-s Abandoned quarry, adjacent soil 439.0 ± 44.5 60.0 ± 4.6 43.0 ± 3.9 155.3 Average ± SD 318.9 ± 163.9 36.1 ± 16.3 21.8 ± 10.2 91.8 ± 34.6 Kajaran Pooled sample Control site 215.0 ± 23.7 93.0 ± 14.0 45.5 ± 2.3 174.6 K-30 Urban agriculture site, undisturbed soil 0.017 ± 0.0017 0.002 ± 0.0006 0.0045 ± 0.0003 0.0095 K-9 Urban agriculture site, undisturbed soil 434.0 ± 43.4 150.0 ± 22.5 52.0 ± 3.1 257.8 K-26 Public garden, urban soil 535.7 ± 57.2 24.9 ± 3.7 24.5 ± 1.3 101.2 K-42 Residential part, urban soil 813.5 ± 80.4 120.0 ± 23.1 73.1 ± 4.5 287.2 K-43 Residential part, urban soil 933.9 ± 92.9 203.9 ± 27.0 78.0 ± 5.4 377.9 K-48 Residential part, urban soil 472.0 ± 46.3 230.0 ± 34.5 80.4 ± 4.8 390.8 K-4 Tailing site, covering soil 867.0 ± 83.2 98.0 ± 14.7 34.0 ± 2.4 213.4 K-33 Old quarry site, adjacent soil 396.0 ± 43.6 70.0 ± 10.5 26.0 ± 2.7 137.7 K-47 ZCMC site, urban soil 643.0 ± 62.9 120.5 ± 15.8 74.6 ± 2.4 276.7 Average ± SD 531.0 ± 294.49 111.0 ± 71.80 109.3 ± 27.57 308.2 ± 122.31
The outdoor gamma absorbed dose rate (ODRA) was calculated was below the MDA, which prevented further statistical treatment from the concentrations of radionuclides in soil (UNSCEAR, 2000)։ of that data. In soil samples from Kajaran the total alpha activity exhibited high variability from site to site, the sample is charac- ¼ : þ : þ : ODRA 0 462CU 0 604CTh 0 0417CK terized by the presence of many outliers, and the presence of a long The annual effective dose equivalent (AEDE) in was calculated left tail in results distribution (Table 1, Fig. 4). Log-transformed data using the following equation: lead to a similar result which implies the necessity of sample size enlargement for achieving statistical characterization of total alpha AEDE ¼ ODRA DCF OF T activity in Kajaran. The coefficient of variation of total beta activity results for the where DCF is dose conversion factor (0.7 Sv/Gy), OF is outdoor two towns is similar, i.e., 0.30 and 0.29 for Kapan and Kajaran, occupancy factor (0.2), and T is the time (8760 h/y) (UNSCEAR, respectively. In both set of results the median is close to the mean 2000). value, which along with the comperatively low coefficient of vari- The excess lifetime cancer risk (ELCR) estimates the probability ation indicates symmetry in data distribution (Fig. 4, histograms of cancer incidence in a human population for a specific lifetime and normal Q-Q plots). However, high values of skewness and from the exposure to naturally occurring radionuclides. The ELCR kurtosis suggest that data are skewed and heavy-tailed and do not was calculated using the equation: follow a normal distribution.
ELCR ¼ AEDE DL RF 3.2. Distribution of total alpha and total beta activities in urban where DL is duration of life (70 year), and RF is the risk factor of soils contracting a fatal cancer per Sievert (Sv 1) received. For stochastic effects, the ICRP 60 uses values of 0.05 for the public (ICRP, 1991; Maps of spatial distribution of total alpha and total beta activ- Taskin et al., 2009). ities in soils from Kapan and Kajaran are displayed in Figs. 5 and 6. The results from this research in Kapan and Kajaran areas were Interpolation IDW method was used for visualization of spatial compared with results reported from metal mining centers and distribution. However, in the case of Kapan as most measurements urban areas worldwide (Alazemi et al., 2016; Asgharizadeh et al., of soil samples for total alpha activity was lower than the MDA, the 2013; Bangotra et al., 2018; Kamunda et al., 2016; Njinga and
Tshivhase, 2016; Ogundare and Adekoya, 2015; Reddy et al., 2017; Table 3 Sethy et al., 2014; Taskin et al., 2009). Correlation between total beta activity and radionuclide activity concentrations in soils.
Total alpha Total beta 40K 238U 232Th RaEq 3. Results and discussion Total alpha 1 3.1. Statistical analysis Total beta 0.350 1 40K 0.063 0.610** 1 238U 0.160 0.607** 0.577** 1 Descriptive statistics of total alpha and total beta activity mea- 232Th 0.165 0.578** 0.630** 0.869** 1 surements made in soils from Kapan and Kajaran are shown in RaEq 0.058 0.672** 0.740** 0.934** 0.953** 1 Table 1. *Correlation is significant at the 0.05 level (2-tailed). ** In 66% of the soil samples from Kapan the total alpha activity Correlation is significant at the 0.01 level (2-tailed). O. Belyaeva et al. / Chemosphere 225 (2019) 859e870 867
spatial distribution of this parameter was visualized using gradu- with a mean value of 363.7 Bq kg 1, while the total beta activity of ated points (Fig. 5, top). the soil from the control site was 350 Bq kg 1. Results for total alpha activity in Kapan soils varied from
Fig. 7. Distribution of four estimated radiological indices values (RaEq, ODRA, AEDE, ELCR) in Kapan and Kajaran. 868 O. Belyaeva et al. / Chemosphere 225 (2019) 859e870
The residential zone of Kapan is located in the valley running 3.3. Radionuclides in soils of Kapan and Kajaran and related east-west (Fig. 2) and soils from this zone displayed total beta ac- radiological hazard indices tivity in the range 200e300 Bq kg 1, which is higher than the background level from the control site, 180 Bq kg 1 (Fig. 6, top). The Activity concentrations of natural radionuclides 238U, 232Th and highest levels of total beta activity in soils from Kapan were 40K in selected urban soils and calculated radium equivalent ac- recorded in a sampling location adjacent to the abandoned quarry tivity (RaEq) values are presented in Table 2. north of the town, and by the Shahumyan mine and waste rock Significant correlation was observed between the total beta piles east of the town. The material in these waste piles is sterile activity and activity concentrations of specific radionuclides, with rock brought from the quarry. The spatial distribution of total alpha RaEq levels in urban soils analyzed (Table 3) while no significant and total beta activity of top soils showed enhanced concentrations correlation was found between total alpha activity in soils and any in the valleys compared with soils from higher altitude. This dis- other parameters investigated. tribution indicates the abandoned quarry and waste rock piles near In Kapan, the activity concentrations of 238U, 232Th and 40K Shahumyan mine, both located on the mountain flanks at high varied within ranges 13.8e61.0, 7.0e43.0 and 113.0e598.0 Bq kg 1, altitude, as the source of enhanced radioactivity levels in soils of the respectively. The maximal activity concentrations of radionuclides urban area and lowlands in general. Similar spatial distribution were recorded near dump sites, where the highest values for total features, have been reported for other settings, and generally wind beta activity and RaEq were determined as well (Fig. 7). In soils and surface water are the transportation agents for contaminants sampled from the residential zone, public garden, and urban agri- carried to lowlands near mining areas (Bruneton and Cuney, 2016). culture zone of Kapan the RaEq levels were around, either slightly In Kajaran, most of the soils displayed total alpha activity levels lower or slightly higher only than the background value (Table 2, below the background value, 23.85 Bq kg 1. The fields with higher Fig. 7). total alpha activity in soils were located mainly north and south- In Kajaran, the activity concentration of 238U, 232Th and 40K west of the town where no mining activity took place (Figs. 2 and spread over five orders of magnitude: 0.002e230.0, 0.004e80.4 5). However, in this zone of highlands the intrusive rocks are and 0.02e933.9 Bq kg 1, respectively (Table 2). Here, the average dominating in the geological structure. levels of RaEq were above the RaEq value for the controlsite, and The average total beta activity of Kajaran soils was about 1.6 soils from some locations in the residential zone of Kajaran times higher than in Kapan. In Kajaran the total beta activity in soils exceeded the RaEq world average, 370 Bq kg 1 (Fig. 7)(UNSCEAR, ranged from 300 to 400 Bq kg 1 but only part of these values were 2000). It is noteworthy that in one undisturbed soil sample (K-30, above the background, i.e. 350 Bq kg 1 (Fig. 6, bottom). The highest Table 2), collected near an urban agriculture site, anomalous low total beta activity values in Kajaran were recorded near the ore activity concentrations for all radionuclides were recorded, sug- mining and ore milling combine (ZCMC), while at west of Kajaran, gesting that materials from artificial origin may have been mixed by the open pit mine, the geology is featured by intrusive rocks and with the soil. Therefore, results for this station were excluded from the central and eastern parts of the urban territory are composed of further calculations of mean radiological hazard indices for Kajaran. volcanic formations. Thus, the fields displaying the high levels of The hazard indices ODRA, AEDE and ELCR were calculated in total alpha and total beta activities in Kajaran were confined to the order to assess the radiation dose rate and human health risks due zone of intrusive rocks. The overall pattern of spatial distribution of to radionuclide content in soils of both mining towns. The values of total alpha and beta activities in Kajaran suggests domination of the these indices are presented in Table 4 and visualized on Fig. 7. The geogenic input over mining activities in the formation of soil range and mean values of these indices were compared with results radioactivity. from similar research carried out worldwide and the levels
Table 4 Outdoor absorbed dose rate in air (ODRA), annual effective dose equivalent (AEDE) and excess lifetime cancer risk (ELCR) from natural radionuclides in soils of Kapan and Kajaran.
Sample code Description ODRA (nGy h 1) AEDE (mSv y 1) ELCR (unitless)
Kapan Pooled sample Control site 38.3 0.05 1.6E-04 KF-79-s Public garden, urban soil 34.2 0.04 1.5E-04 KF-97-s Public garden, urban soil 50.2 0.06 2.2E-04 KF-115-s Residential part, urban soil 17.7 0.02 7.6E-05 KF-35-s Residential part, urban soil 31.6 0.04 1.4E-04 KF-53-s Residential part, urban soil 38.6 0.05 1.7E-04 KF-128-s Residential part, urban soil 42.7 0.05 1.8E-04 KF-29-s Town border, adjacent soil 39.4 0.05 1.7E-04 KF-20-s Shahumyan mine, adjacent soil 66.7 0.08 2.9E-04 KF-119-s Abandoned quarry, adjacent soil 72.0 0.09 3.1E-04 Kajaran Pooled sample Control site 79.4 0.10 3.4E-04 K-30 Urban agriculture site, undisturbed soil 0.00003 0.00424 1.8E-08 K-9 Urban agriculture site, undisturbed soil 118.8 0.15 5.1E-04 K-26 Public garden, urban soil 48.6 0.06 2.1E-04 K-42 Residential part, urban soil 133.5 0.16 5.7E-04 K-43 Residential part, urban soil 180.3 0.22 7.7E-04 K-48 Residential part, urban soil 174.5 0.21 7.5E-04 K-4 Tailing site, covering soil 102.0 0.13 4.4E-04 K-33 Old quarry site, adjacent soil 64.6 0.08 2.8E-04 K-47 ZCMC site, urban soil 127.6 0.16 5.5E-04 O. Belyaeva et al. / Chemosphere 225 (2019) 859e870 869
Table 5 Radiological indices from the present study. For comparison results reported from other regions and countries are compiled herein.
Region and reference ODRA (nGy h 1) AEDE (mSv y 1) ELCR (unitless)
Tehran, Iran (Asgharizadeh et al., 2013) mean 69.1 0.08 e range 50.6e88.7 0.06e0.11 e Uranium mining area of Jharkhand, India (Sethy et al., 2014) mean 80 0.098 3.9E-04 range 26e139 0.03e0.17 1․2E-04 e 6.5E-04 Barnala and Sangrur districts of Punjab, India (Bangotra et al., 2018) mean 60 0.07 2.9E-04 range 52e69 0.06e0.08 2.1E-04 e 2.8E-04 State of Kuwait (Alazemi et al., 2016) mean 33.16 0.04 e range 7.96e47.19 0.01e0.06 e Gold Mine Tailings in the Province of Gauteng in South Africa (Kamunda et al., 2016) mean 407.1 ± 6.4 0.5 e range 74.5 ± 1.0e1297.3 ± 21.4 0.1e1.2 e Aluu and Rumuolumeni landfills, Rivers state, Nigeria (Ogundare and Adekoya, 2015) mean 45.96 0.05 7.9E-04 range 20.79e67.86 0.03e0.08 3.6E-04 e 11.7E-04 Kolar Gold Fields, Kolar district, Karnataka, India (Reddy et al., 2017) mean 84.9 0.1041 e range 49.7e116.3 0.06e0.14 e Kilklareli, Turkey (Taskin et al., 2009) mean 118 0.14 5.1E-04 range 28e283 0.8e0.18 1.0Е-04 e 12.0Е-04 Kapan, Armenia, present study mean 43.1 0.05 1.9E-04 range 17.7e72.0 0.02e0.09 0.8E-04 e 3.1Е-04 Kajaran, Armenia, present study mean 114.4 0.14 4.9E-04 range 48.6e180.3 0.06e0.22 2.1Е-04 e 7.7Е-04 World average (UNSCEAR, 2010, 2000) mean 59.00 0.07 2.9E-04 range 18e93 ee
“e” not available. recommended by UNSCEAR (2010) (Table 5). that in Kapan the soil radioactivity levels, although enhanced by Based on the radionuclide content of Kapan soils, the calculated metal mining, are not a significant risk factor to human health. In ODRA values vary from 17.7 to 72.0 nGy h 1, averaging 43.1 nGy h 1, Kajaran, the soil radioactivity levels in some areas were above the which is below the world average value of 59 nGy h 1 (UNSCEAR, background values, but radionuclides originated in a natural and 2000). The higher ODRA values were calculated for the sampling unmodified geogenic source and not from mining activities. locations near waste rock dumps (Fig. 7). Thealculated c values for Generally with this study no significant radiological risks were AEDE showed variation in the range 0.02e0.09 mSv y 1, and the identified in the region in relationship with copper and gold- highest values were obtained for the same locations near waste polymetallic ore mining, and transport of naturally occurring ra- rocks dump sites, and with soils impacted by mining (Fig. 7). The dionuclides from quarries and waste rock piles into urban soils. highest value of the ELCR was equal to the world average, 2.9E-04 Further investigations on enhanced environmental radioactivity in (Taskin et al., 2009). Furthermore, the mean level of ELCR in Kapan, relationship with other phases of the milling process, namely ore calculated at 1.9E-04, was notably lower than world average smelters, are still needed in order to complete the assessment of (Table 5). occupational radiation exposure to NORMs. Notwithstanding, this In Kajaran, the computed ODRA values varied from 48.6 to wide environmental radioactivity survey in polymetallic mining 180.3 nGy h 1, with an average value of 114.4 nGy h 1. The AEDE areas of Armenia answered to the regional concerns related to value calculated for the control site, the urban residential and the radioactivity in mining waste legacy and exposure of the public. industrial areas exceeded the worldwide average for background Plans for environmental remediation of mining legacy and current radiation areas (UNSCEAR, 2000). The AEDE values calculated for environmental monitoring may concentrate mainly on stable toxic Kajaran varied between 0.06 and 0.22 mSv y 1, with a mean value metals which were identified as a threat to public health. of 0.14 mSv y 1. In 60% of sampling locations, the ELCR values exceed the world average level of 2.9E-04, but it is within the range Acknowledgement of values reported for other mining regions (Table 5, Fig. 7). Overall, the radiological hazard indices determined with this Soil survey implementation in Kajaran was supported by the research on Kapan and Kajaran towns were similar to results ob- OSCE office in Yerevan and Kajaran Municipality (2005). The soil tained in non-uranium mining centers (Kamunda et al., 2016; survey in Kapan was supported by OSCE office in Yerevan (2007). Ogundare and Adekoya, 2015; Reddy et al., 2017) and urban areas Authors acknowledge support of the Environmental Geochemistry (Alazemi et al., 2016; Asgharizadeh et al., 2013; Taskin et al., 2009) department of CENS for providing the materials of soil surveys. (Table 5).
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