Natural Radioactivity in Urban Soils of Mining Centers in Armenia: Dose Rate and Risk Assessment
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Chemosphere 225 (2019) 859e870 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere 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 Tecnico/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 À 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 À 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 39120 and E 46240), 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 À3 CtoÀ4 C, with an absolute Furthermore, several abandoned waste-rock piles from mine minimum of À30 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 Ctoþ21С with the absolute maximum of þ35С). 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 À0.8 À0.6 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.