Comparative analysis of water contamination of the Shagan river at the Semipalatinsk test site with heavy metals and artificial radionuclides

Journal of Environmental Radioactivity xxx (xxxx) xxx

Contents lists available at ScienceDirect

Journal of Environmental Radioactivity journal homepage: http://www.elsevier.com/locate/jenvrad

Comparative analysis of water contamination of the Shagan river at the Semipalatinsk test site with heavy metals and artificial radionuclides I. Gorlachev a, *, P. Kharkin a, M. Dyussembayeva b, S. Lukashenko c, G. Gluchshenko a, L. Matiyenko a, D. Zheltov a, A. Kitamura d, N. Khlebnikov e, f a

Institute of Nuclear Physics, 050032, Ibragimov 1, Almaty, Kazakhstan Institute of Radiation Safety and Ecology National Nuclear Center, 071100, Krasnoarmeiskaya 2, Semipalatinsk Region, Kurchatov, Kazakhstan Russian Institute of Radiology and Agroecology, Obninsk, Russia d Fukushima Environmental Safety Center, Japan Atomic Energy Agency, 10-2 Miharu, Fukushima, Japan e Ural Federal University, Yekaterinburg, 620002, Russia f Institute of Solid State Chemistry, Ural Branch, Russian Academy of Sciences, Yekaterinburg, Russia b c

A R T I C L E I N F O

A B S T R A C T

Keywords: Semipalatinsk test site Shagan river Heavy metals Artificial radionuclides Management

The purpose of this paper is to determine the degree of contamination of the largest waterway of the Semi­ palatinsk Nuclear Test Site (STS), the Shagan River, with heavy metals and artificial radionuclides. With the data obtained by the long term monitoring results, we identified the most significant contaminants and determined the most contaminated reaches of the Shagan River. The contamination indices for heavy metals were calculated and applied to evaluate possible usage of the Shagan River water for domestic purposes.

1. Introduction Currently, more than 25 operating or decommissioned nuclear test sites exist in the world. In total, more than two thousands of nuclear explosions were performed by the nuclear states. Nuclear test explosions have been conducted in the atmosphere, on the Earth’s surface, under­ ground, and underwater. All nuclear explosions have similar physical and biological effects. In terms of energy released in nuclear explosions, two different processes were involved, namely fission (of 235U and 239Pu isotopes in chain reactions) and fusion (of the hydrogen isotopes, deuterium and tritium, in thermonuclear processes). In terms of radio­ activity, the fission process produces a whole range of radionuclides, while the fusion process generally produces only tritium (3H). However, the fusion process can also generate other radioactive materials, because of the inherent fission process of certain stages of the thermonuclear reactions (resulted in large amounts of radioactive debris). Currently, the former Soviet region of Semipalatinsk (Semey) is the most heavily contaminated site among the Soviet nuclear test sites. Nuclear explosions here were performed on the specially prepared areas only, not on the whole territory. In total, 456 nuclear tests were con­ ducted (616 nuclear explosions). The Semipalatinsk Test Site (STS) total area is 18 500 km2. Specialized studies have shown that, currently soil

and vegetation of the Semipalatinsk region are heavily contaminated with radioactive isotopes, such as 90Sr, 137Cs, 239 240Pu, and 241Am (IAEA, 1998; Kadyrzhanov et al., 2005). It was also found that the local water objects are heavily contaminated by the radioactive uranium isotopes (234,235,238U), well above the maximum acceptable value (MAC) by the World Health Organization, 15 μg/l (Yamamoto et al., 2010). While the most critically contaminated areas were found to be Ground Zero (the central-northern area of Semipalatinsk) and the Balapan Lake (south-eastern central part), significant levels of radioactivity were also recorded in the Tel’kem and Sary-Uzan areas (IAEA, 1998). Although there are no permanent human settlements in Ground Zero and Balapan, it is estimated that the annual effective dose for the people who visit these areas daily is of 10 mSv per day (compared, for instance, with the worldwide individual average annual dose of 2.4 mSv per year from all natural sources), and that, in case if permanent settlements be estab­ lished there, the annual exposure will be of approximately 140 mSv (IAEA, 1998). For many years, the STS is considered as the source of radiation hazard for the local population. From this point of view, the territory of STS has been studied in detail (IAEA, 1998; Kadyrzhanov et al., 2005; Aidarkhanov et al., 2013; Panitskiy and Lukashenko, 2015). The major sources of radioactive contamination and the current/future

* Corresponding author. E-mail address: [email protected] (I. Gorlachev). https://doi.org/10.1016/j.jenvrad.2019.106110 Received 3 July 2019; Received in revised form 13 November 2019; Accepted 15 November 2019 0265-931X/© 2019 Elsevier Ltd. All rights reserved.

Please cite this article as: I. Gorlachev, Journal of Environmental Radioactivity, https://doi.org/10.1016/j.jenvrad.2019.106110

I. Gorlachev et al.

Journal of Environmental Radioactivity xxx (xxxx) xxx

distributions of radioactive substances have been identified. One of the most important results of these works was that a part of STS territory is “clean” and can be used for the national economy (Lukashenko et al., 2010, 2012a, 2012b). This made it possible to significantly reduce radiophobia among the population living in close proximity to STS. At the same time, it is necessary to take into account that the radi­ ation factor is not the only population health affecting indicator. Often, the quality of environmental service objects (primarily drinking water) is characterized by the content of chlorides, sulfites, total salinity and availability of heavy trace elements. The previous studies (Panin and September 2003) have shown there are areas with a high content of heavy elements, which are characterized by high toxicity and carcino­ genic effects. One of the consequences of their effects is gene mutations similar to those caused by ionizing radiation. The STS ecosystem consists of the tungsten mineralized ore field formed by the group of greisen bodies on the western slope of the Degelen Mountains and tungsten-molybdenum ore of Mailykar and the Karadzhal deposits in the northern part of the Degelen Mountains. They are represented by magnetite, garnet-fluorite and other skarns. At present, economic activities are developed in the Test Site area: coal deposit is developed in the Karazhyra, salt is extracted from the Zhaksytuz lake, the geological survey and exploration activities take place, and hay is gathered and cattle is grazed. Such activities are associated with additional risk for the workers and the consumers. The places of permanent residence (wintering) of shepherds and their fam­ ilies appeared at STS; herds of sheep and horses are grazed throughout the Test Site. Therefore, the ecological aspect of the environmental study is important in terms of their potential impact on the health of local population. The largest waterway of STS, the Shagan River, was chosen as the object of our research. The Shagan River on the territory of STS is the largest and longest surface watercourse, and its main waterway is con­ nected to the left-bank tributary of the Irtysh River - the largest river in East Kazakhstan. Thus, the water quality of the Shagan River not only largely determines the ecological aspect of STS, but also affects the ecosystem of the entire East Kazakhstan region. As a result of nuclear tests at STS, the valley of the Shagan River was radioactively contaminated with various degrees. Basically, the radio­ active contamination of the river is concentrated in the area of the “Atomic” lake, where the excavation-type nuclear explosion was made. In addition, the contamination of the Shagan River was caused by the underground nuclear tests in the “military” wells of the “Balapan” site. Minor contribution to the contamination was made by the above-ground nuclear tests performed at the “Opytnoe pole” site and the global fallout. The studies performed in 2006–2009 revealed high concentrations of 3 H in the Shagan River water at 5 km distance downstream from the “Atomic” lake (Aidarkhanov et al., 2010). The studies performed in 2014 showed that in the Shagan River water, the average concentrations for elements such as strontium, lithium, iron and uranium significantly exceeded levels in global natural waters and water quality targets (Tashekova et al., 2016). The most serious water contamination with heavy metals is typical for the Shagan River stretch from the “Atomic” lake to its inflow to the Irtysh River. The previous studies did not con­ sistency clarified the water quality of the Shagan River. The aim of the presented studies was to determine the degree of water contamination from the Shagan River with heavy elements and artificial radionuclides in different year seasons, with the data obtained by the long term monitoring. Such data allowed us to identify the most significant contaminants, to determine the most “contaminated” points of the Shagan River, to compare the degree of water contamination with heavy metals and artificial radionuclides, and to calculate the indices relating to water quality. Based on the obtained results the recommen­ dations can be made for water use from the Shagan River for household purpose.

2. Study area The artificial water reservoir “Atomic” lake was formed in the Sha­ gan River by the first Soviet industrial thermonuclear explosion, the experiment to create an artificial reservoir, in 1965. This excavation explosion resulted in the most severe radioactive contamination of the Shagan River. The radioecological studies revealed that the significantly high concentrations of anthropogenic tritium radionuclide in the river (Aidarkhanov et al., 2010). Fig. 1 shows the layout of the Shagan River in the STS. The river length is approximately 50 km. The main river and the lower tributaries are mainly snow-fed, while the headwaters are fed by groundwater. This explains the seasonal water regime of the river. The river water is fresh in the upstream and after the confluence of the Aschisu tributary is brackish. The river is characterized by the low flow rate, braiding, dead-end creeks and waterlogging of the banks. The in­ terval of the river from 12 to 15 to 30–40 km from the “Atomic” lake is characterized by the fact that the Shagan River has intermittent watercourse. 3. Materials and methods 3.1. Sampling In 2014, water sampling was performed along the Shagan River from the Atomic Lake to its inflow to the Irtysh River (71 points). The collected samples were analyzed for the content of heavy elements (Tashekova et al., 2016). According to the obtained data, 20 most contaminated sampling points, shown in Fig. 2, were selected to deter­ mine the seasonal variations of chemical elements and radionuclides. The point numbers in Fig. 2 correspond to the distance from the “Atomic” lake. Between points 14 and 50, the seasonal samples were not

Fig. 1. Layout of Shagan River location relative to STS. 2

I. Gorlachev et al.

Journal of Environmental Radioactivity xxx (xxxx) xxx

Fig. 2. Sampling points at the Shagan River. The point numbers correspond to the distance from the Atomic Lake (km).

collected due to the river drying out in summer. In May, August and October of 2018, the seasonal water samples were collected at the points shown in Fig. 2. Sampling and preservation of the water samples was performed in accordance with GOST R 51592-2000 established in the Republic of Kazakhstan, which applies to all types of water and specifies general requirements for sampling, transportation and preparation for storage of water samples intended to determine the parameters of its composition and properties. The following operations were performed during water sampling: water filtering through a blue ribbon paper filter to remove any mechanical impurities; samples preservation by adding the concentrated nitric acid (HNO3) of “very-high-purity” grade at the rate 3 ml of HNO3 per 1 l of water sample. Filtration and preservation were performed at the sampling site. The equivalent dose rates (EDR), as well as flux densities of alpha particles and beta particles were measured for the collected samples using the dosimeter MKC-AT6130. Thus, preliminary information on the sum of radiating alpha- and beta-nuclides can be obtained.

analyzing the elemental composition of liquid samples (water samples). The ICP–MS analysis is performed with the inductively coupled plasma quadrupole mass spectrometer ELAN-9000 (PerkinElmer SCIEX). The standard deviation of the output signal is not more than 6%, the reso­ lution is from 0.6 atomic mass units (amu) to 0.8 amu at 10% peak height, the mass range is from 2 amu to 270 amu. The ICP–OES analysis is performed with the inductively coupled plasma dual-view optical emission spectrometer OPTIMA-8000 (PerkinElmer Inc.). The optical range is 166 nm–900 nm and the resolution at peak half-height is 0.008 nm at 200 nm. For elemental analysis we used the non-diluted water samples (in case of ICP–OES technique) or previously diluted (not more than 5 times with 1% nitric acid) water samples (in case of ICP–MS technique). The additional diluted aqueous samples were used (in 20 or 50 times with 1% nitric acid) if required for the analysis of some analytes in high concentrations (Na, Ca, Mg) with the ICP–OES technique. The water complex contamination index (WCCI HM) is applied to assess the surface water quality for heavy metals, taking into account the hazard class. The calculation of the complex water contamination index is carried out for each hazard class with the inclusion of all elements exceeding the maximum acceptable concentration, MAC, i.e.: � � X n 1 Ci WCCIHMj ¼ ⋅ ; (1) n i¼1 MACi

3.2. Analytical techniques and sample preparation 3.2.1. pH determination Measurement of pH was performed with the pH meter S220 Seven Compact™ according to GOST 264491-85 “Distillation desalination stationary units. Methods of chemical analysis of salt water”. Calibration of the pH meter was performed by the standard-titers for preparation of buffer solutions (GOST 8.135–2004) with pH values of 1.65; 6.86; 9.18; 12.43. An aliquot of 50 ml was taken from the water sample and placed in the measuring cell. The electrodes washed with distilled water and then with the test solution were immersed into it. After that pH was measured. Each sample was measured and each sample was measured twice.

where WCCI HMj is the index of water contamination with the j-group, Сi is the concentration of the i-component of the j-group, mg/l, MACi is the maximum acceptable concentration of the i-component of the jgroup, mg/l, n is the number of the j-group components. 3.2.3. Radionuclide analysis of water samples The study of 3H content. For the study of 3H content, a sample of 5 ml volume was taken from the filtered sample and placed in a plastic vial (20 ml) with addition of the scintillation cocktail in a ratio of 1:3 (the ratio of sample to scintillator). The scintillation cocktail Ultima Gold LLT, designed specifically for 3H measurement in the natural samples was used to analyze the samples (detection efficiency for tritium in the

3.2.2. Elemental analysis Inductively coupled plasma mass spectrometry (ICP–MS) and inductively coupled plasma optical emission spectrometry (ICP–OES) are basic techniques utilized at the Institute of Nuclear Physics for 3

I. Gorlachev et al.

Journal of Environmental Radioactivity xxx (xxxx) xxx

range of 0–18 KeV is about 60%). The liquid scintillation spectrometer TRI-CARB 2900 TR was used to determine the volume activity of 3H in the collected samples. The energy range for 3H determination was set from 0 to 15 KeV. The measurement time of each sample was about 120 min. The method detection limit was 12 Bq/l. The chemical yield of 239þ240Pu was calculated from the results of alpha-spectrometric measurements, based on the known activity of the added 242Pu isotope label. Plutonium was separated on iron hydroxide. For this purpose, 40–70 ml of the iron acid (III) solution with the con­ centration of 10 mgFe/cm3 was added into the solution. The 20% NaOH solution was added in portions to the resulting solution to precipitate iron hydroxyl to pH ¼ 7. The solution was allowed to stand for 12 h and decant. The precipitate of iron hydroxide was then transferred to radiochemical analysis for 239þ240Pu isotope extraction. The specific activity of 239þ240Pu in the prepared sample was determined with the Canberra alpha-spectrometer. The chemical yields of 90Sr and 90Y after the carbonates precipitation were determined according to the results of gamma spectrometric measurements, based on the known activity of the added 85Sr and 88Y isotopic labels, respectively. The strontium isotopes were concentrated by co-precipitation with calcium carbonate by adding the 20% solution of Na2CO3 to pH � 9. After the precipitation, 85Sr was measured to determine the chemical yield, and the 88Y isotope label was added to the resulting solution. The specific activity of 90Sr was calculated from the specific activity of 90Y after the 2-weeks accumulation of 90Y from 90Sr. Measurement of the beta source 90Y was performed with the beta spectrometer TRI-CARB 2900 TR. The chemical yield of 137Cs was calculated according to the results of gamma-spectrometric measurements, based on the known activity of the added 134Cs isotope label. Concentration of 137Cs was performed by coprecipitation with copper ferrocyanides. Precipitate of ferrocyanides containing cesium was measured with the gamma spectrometer Can­ berra GX-2020. It should be noted that the detection limits of the used analytical methods are significantly lower than the level of intervention (IL) for the content of certain radionuclides in drinking water: 137Cs - 11 Bq/l, 90Sr 4.9 Bq/l, 239þ240Pu - 0.55 Bq/l, 3Н - 7600 Bq/l (Hygienic standards, 2012).

hardness are chlorides and sulfates. The dominant cations are Naþ and Kþ. 4.2. Heavy metal contents in Shagan water samples The contents of 23 chemical elements were studied. The results were compared with the values of Maximum Acceptable Concentrations (MAC) in drinking water, established in the Republic of Kazakhstan (Sanitary and Epidemiological Requirements for the Water Sources, 2012; SanPiN, 2004). The excess of MAC values was revealed for 5 el­ ements: U, Fe, Li, Mn and Sr. Table 2 (for elements with contents above the MAC values) shows the average values of the contents of the studied elements for three seasonal sampling (x), the standard deviation for three seasonal data sets (SD) and the range of content variations (Range). In addition, Table 2 indicates the hazard classes and the maximum acceptable concentrations of the trace elements in water, established in Kazakhstan (Sanitary and Epidemiological Requirements for the Water Sources, 2012; SanPiN, 2004), USA (USEPA) (Seither et al., 2012), EEC (Seither et al., 2012) and those approved by the World Health Organization (WHO) (Seither et al., 2012). The complex assessment of the surface waters quality is usually determined by the following hydro-chemical parameters: 1. the main ions (Са, Mg, Na þ K, SO4, etc.); 2. heavy metals; 3. nutrients (NH4, NO2, NO3, P, etc.); 4. toxic substances (CN, SCN, F, H2, nitrobenzene, etc.); 5. organic substances (oil products, resins, synthetic surfactants, phenols, fats, etc.); 6. organochlorine compounds (DDT, DDD, DDE) (Burlibaeva, 2012). The water complex contamination index (WCCI HM) is applied to assess the surface water quality for heavy metals, taking into account the hazard class (Burlibaeva, 2012). Table 3 shows the classification of water objects depending on the contamination degree - the WCCI HM indicator. Using formula (1), the WCCI HM values were calculated for the average values of the seasonal water samples of the Shagan River. The obtained WCCI HM values are provided in Table 2 for the each hazard class. The calculations were made only for points where average values exceed MAC. In the WCCI HM columns, the green, yellow, and red highlighted columns indicate that these values correspond to the standard-clean level, the moderate level, and the high level of water contamination with heavy metals in the classification given in Table 3, respectively. In Table 2, only one element (uranium) corresponds to the first class of hazard. Fig. 3 shows the distribution along the Shagan River of the average seasonal uranium contents normalized by MAC. The highest uranium contents are present at points 5–54. At all these points, the average uranium contents exceed the MAC value more than 2 times and, as a result, water corresponds to the moderate level of contamination. At points 1, 2 and 55–80, the uranium contamination level is lowered and the water is referred to the category of standard-clean. Finally, at points 83–106, i.e. near the confluence of the Shagan River into the Irtysh River, the average uranium contents become lower than MAC value, although in spring and sometime in summer the uranium contents reach the MAC value. From the point of view of seasonal variations, the “cleanest” season of the year is autumn since the average uranium content along the river is 21 μg/l, and the most “contaminated” is spring since the average uranium content along the river is 28 μg/l. The highest uranium contents are observed at points 6, 13 and 14 of spring sampling with values of 44, 48 and 47 μg/l, respectively. The increased uranium content in the spring is apparently due to the influx of this chemical element from the catchment areas together with melt water (Yaki­ menko, 2013). Lithium and strontium represent the second hazard class in Table 2. Distribution of the average seasonal contents of the second hazard class elements normalized by MAC along the Shagan River is shown in Fig. 4. For this class, the WCCI HM values at all sampling points are greater than 1 and the lithium contents exceed the MAC value. The points near the “Atomic” lake are classified as standard-clean. From point 50 to the

4. Results and discussion 4.1. Physical-chemical parameters of Shagan water Some physicochemical parameters of water samples of the Shagan кiver were analyzed (Table 1). As follows from Table 1, the water of the Shagan River is mostly alkalescent in terms of pH alkaline (pH ¼ 7.1–8.6). Such waters are typical for the seas and oceans, steppes and deserts and underground waters in limestone. Carbonic and organic acids appear during decomposition of organic substances, but they are completely neutralized by calcium, magnesium, sodium, and potassium. At the points 50 and 51 the water becomes alkaline (pH ¼ 8.5–8.6). The availability of sodium carbonate explains the reaction for these waters. The anionic elements (As, V, U, Mo) migrate easily in sodium carbonate waters. In accordance with the data of Table 1, the water samples from the Shagan River are characterized by high salt content. The values of total mineralization along the Shagan River vary from 4 g/l to 9 g/l, which classifies the water as brackish. Under the conditions of arid climate, the salinity of water is caused by the processes of salts evaporation con­ centration, i.e. capillary rise of more mineralized soil water and groundwater to the surface on the one hand, and concentration of salts in the river water on the other hand. The total mineralization is slightly reduced when approaching the place of the confluence of the Shagan River into the Irtysh River. (points 104 and 106). The hardness of the Shagan River varies along the river from 32 to 56 mmol/L. The main salts forming the high level of mineralization and 4

I. Gorlachev et al.

Table 1 Physical-chemical parameters of the Shagan water samples. Sampling point

Т-1 Т-2 Т-5 Т-6 Т-13 Т-14 Т-50 Т-51

5

Т-54 Т-55 Т-65 Т-66 Т-79 Т-80 Т-83

Т-95 Т-96 Т-104 Т-106

pH

xþSD

Range

xþSD

Range

xþSD

Range

xþSD

Range

xþSD

Range

xþSD

Range

xþSD

Range

xþSD

Range

xþSD

Range

32.7 � 1.2 36.7 � 2.9 49.7 � 0.6 60.0 � 0 57.3 � 2.3 58.7 � 1.2 51.3 � 1.2 60.3 � 0.6 53.0 � 2.6 50.0 � 0 51.3 � 1.2 50.7 � 1.2 45.0 � 5.0 49.0 � 3.6 46.7 � 1.2 52.0 � 0 55.0 � 0 50.7 � 1.2 51.0 � 1.0 55.3 � 0.6

32–34

7.7 � 0.2 7.2 � 0.1 7.1 � 0.1 8.3 � 0.1 7.3 � 0.2 7.4 � 0.1 8.5 � 0.1 8.5 � 0.2 8.2 � 0.3 7.3 � 0.1 8.1 � 0.1 7.3 � 0.2 8.1 � 0.2 7.4 � 0.2 7.5 � 0.2 7.7 � 0.1 7.5 � 0.2 7.6 � 0.2 7.6 � 0.1 7.7 � 0.1

7.5–7.8

1252 � 90 1532 � 16 1889 � 69 1487 � 8 1721 � 210 1843 � 243 1891 � 146 1442 � 72 1430 � 90 1408 � 172 1730 � 147 1385 � 209 1087 � 483 1176 � 222 1443 � 133 1144 � 2 902 � 195 983 � 178 669 � 155 718 � 373

1200–1356

243 � 6 267 � 29 273 � 23 413 � 12 413 � 12 373 � 23 433 � 29 438 � 42 413 � 12 400 � 20 433 � 29 353 � 6 323 � 25 363 � 32 390 � 9 340 � 17 500 � 0 460 � 17 430 � 17 457 � 40

240–250

249 � 11 284 � 17 434 � 7 478 � 7 446 � 35 486 � 0 361 � 3 472 � 18 393 � 25 365 � 12 361 � 3 401 � 16 351 � 46 375 � 63 330 � 9 239 � 172 365 � 0 205 � 113 290 � 130 396 � 27

243–262

2367 � 115 2367 � 115 2700 � 346 2253 � 40 2475 � 152 3073 � 237 2833 � 29 2333 � 153 2477 � 68 2420 � 106 2604 � 94 1580 � 69 1633 � 569 1340 � 151 1700 � 87 1502 � 3 1607 � 168 1640 � 314 1457 � 23 1450 � 229

2300–2500

100 � 0 283 � 58 413 � 12 523 � 64 537 � 75 454 � 3 503 � 46 651 � 200 417 � 15 413 � 15 513 � 55 573 � 108 423 � 75 463 � 51 517 � 29 450 � 0 507 � 98 421 � 61 276 � 21 500 � 304

–

900 � 87 1533 � 29 2333 � 289 2523 � 20 2573 � 64 2153 � 133 2181 � 294 2253 � 234 1850 � 87 1740 � 218 2154 � 365 2735 � 204 1887 � 487 2630 � 82 2547 � 127 2500 � 0 1951 � 217 1933 � 57 1672 � 367 1800 � 300

850–1000

4914 � 103 6030 � 449 7252 � 71 7598 � 361 7847 � 794 8080 � 325 7451 � 516 7572 � 946 6496 � 252 6282 � 295 7505 � 1010 7262 � 861 5548 � 1408 6187 � 395 6490 � 281 6236 � 247 5701 � 348 5519 � 461 4612 � 369 5085 � 1518

4845–5032

35–40 49–50 – 56–60 58–60 50–52 60–61 50–55 – 50–52 50–52 40–50 45–52 46–48 – – 50–52 50–52 55–56

Cation content, mg/l

7.1–7.3 7.0–7.2 8.2–8.3 7.2–7.5 7.3–7.5 8.4–8.5 8.3–8.6 8.0–8.5 7.2–7.3 8.0–8.2 7.2–7.6 8.0–8.3 7.2–7.5 7.3–7.6 7.7–7.8 7.2–7.6 7.4–7.7 7.5–7.7 7.6–7.7

Anion content, mg/l Ca2þ

NaþþKþ

1523–1551 1849–1969 1478–1491 1478–1842 1563–1987 1804–2059 1369–1512 1327–1495 1210–1519 1633–1900 1143–1512 533–1421 957–1400 1290–1520 1143–1147 763–1125 836–1181 579–848 364–1108

Mg2þ

250–300 260–300 400–420 400–420 360–400 400–450 389–462 400–420 380–420 400–450 350–360 300–350 340–400 385–400 320–350 – 450–480 420–450 420–500

Cl

274–304 426–438 474–486 426–486 – 359–365 461–493 365–414 353–377 359–365 389–420 304–395 304–426 325–341 140–438 – 140–335 140–365 365–414

2300–2500 2500–3100 2230–2300 2300–2563 2800–3210 2800–2850 2200–2500 2400–2530 2300–2500 2512–2700 1500–1620 1000–2100 1200–1500 1600–1750 1500–1505 1500–1800 1420–2000 1430–1470 1200–1650

Total mineralization, mg/l

SO24

HCO3

250–350 400–420 450–560 450–580 450–456 450–530 450–850 400–430 400–430 450–550 450–650 350–500 420–520 500–550 – 450–620 350–462 264–300 300–850

1500–1550 2000–2500 2534–2500 2500–2610 2000–2230 2000–2520 2000–2460 1800–1950 1500–1920 1800–2530 2500–2855 1350–2300 2540–2700 2400–2620 – 1802–2200 1870–1980 1460–2096 1500–2100

5560–6455 7170–7300 7183–7777 7000–8575 7800–8437 7000–8013 6500–8293 6243–6746 5946–6500 6500–8520 6500–7680 3923–6420 5920–6640 6200–6762 6010–6500 5319–6000 4987–5800 4306–5050 3797–6758

Journal of Environmental Radioactivity xxx (xxxx) xxx

Т-84

Hardness, mmol/ l

I. Gorlachev et al.

Journal of Environmental Radioactivity xxx (xxxx) xxx

Table 2 The Shagan water contaminants (element contents above the MAC value), the water contamination complex indexes and the degree of water contamination with heavy metals.

Table 3 Classification of water objects according to the degree of contamination with heavy metals. Contamination degree

Estimated indicators of water objects contamination by WCCI HM taking into account the hazard class

Standard-clean Moderate level of contamination High level of contamination Extremely-high level of contamination

�2.0 2.1–6.0 6.1–10.0 �10.1

confluence of the Shagan River into the Irtysh River, the collected water samples are referred as the moderate level of contamination. The most “contaminated”, in terms of the average seasonal content of elements, are points 80 and 83. The WCCI HM values at these points are 4.0 and 4.2, respectively. From the point of view of seasonal variations, the most “clean” season is autumn since the average lithium and strontium con­ centrations along the river are 87 μg/l and 6025 μg/l, respectively. The difference between spring and summer is insignificant in terms of the average contents of lithium and strontium along the river. The highest lithium content of 250 μg/l is observed at the point 66 for summer sampling. The highest strontium content of 11 000 μg/l is observed at points 50, 51 and 66 for summer sampling. Iron and manganese represent the third hazard class in Table 2. Distribution of the average seasonal contents of the third hazard class elements normalized by MAC along the Shagan River is shown in Fig. 5.

Fig. 3. Distribution along the Shagan River of the average seasonal uranium contents, normalized by MAC.

For this class, the WCCI HM values at all sampling points are greater than 1 and the average seasonal contents of iron exceed the MAC value everywhere except points 1–5. Almost all points except the points 1, 2, 66 and 84 are classified as standard-clean. The points 2, 66 and 84 are referred as the moderate level of contamination. And only point 1 is classified as high level of contamination due to the high content of manganese. From the point of view of the seasonal variations, the most “clean” season of the year for the third hazard class elements, as well as 6

I. Gorlachev et al.

Journal of Environmental Radioactivity xxx (xxxx) xxx

these radionuclides, 137Cs and 90Sr are the fission products of uranium and plutonium during the nuclear explosions. Europium isotopes were generated as a result of induced activity in the capture of neutrons by various elements that are part of the nuclear device, soil, water and other elements surrounding the explosion site. The induced activity is of particular importance in the explosion of thermonuclear charges, which are accompanied by powerful neutron fluxes. Finally, plutonium iso­ topes are the remains of fissile material. Plutonium isotopes are always accompanied by 241Am. 241Am is a decay product of 241Pu, which con­ tent in the weapons-grade plutonium is an order of magnitude greater than 239Pu. With a relatively short half-life (14 years), 241Pu quickly decays into 241Am (Т1/2 ¼ 432 years). The requirements for the population protection from exposure due to the presence of natural and man-made radionuclides in drinking water were introduced in Russia in 1996 for the first time and also established in Kazakhstan. According to the Radiation Safety Standards (RSS) established in 1996, the total radiation dose of an adult by drinking water should not exceeds 0.2 mSv/year. Three years later, this dose limit was transformed into the intervention limit (IL) - the level of the radi­ ation factor (Ionizing radiation and radia, 1999), the excess of which is the basis for considering the need for measures to reduce the content of individual radionuclides in drinking water. When the content of natural and artificial radionuclides in drinking water, contribute an effective dose of less than 0.1 mSv per year, no measures are required to reduce its radioactivity (ICRP, 1991). When water consumption is 2 l per day, this average dose corresponds to the average annual specific activity of in­ dividual radionuclides (Bq/l) - intervention levels (IL). With the joint P presence of several radionuclides in water, the condition must be met: (Ai/ILi) � 1, where Ai - specific activity of the i-th radionuclide in water, ILi - intervention level of the corresponding radionuclide. If this condi­ tion is not fulfilled, the protective actions should be carried out taking into account the principle of optimization. Twenty water samples collected from the Shagan River were analyzed by us for seasonal variations in the content of artificial radio­ nuclides. The EDR values in the collected samples ranged from 0.10 to 0.12 μSv/h, which is at the level of background values typical in this area. The flux of alpha particles in the samples was not detected, the flux of beta particles was below the detection limit of the method (10 par­ ticles/(min⋅сm2)). Table 4 presents the obtained results for 90Sr, 3H and 239þ240 Pu and the established IL in Kazakhstan (Ionizing radiation and radia, 1999). Table 4 shows the average values of radionuclides specific activities for three seasonal sampling (x), the standard deviation for three seasonal data sets (SD) and the range of variations in the activities (Range). The measured activities of radionuclides 241Am, 137Cs, 152Eu, 154 Eu and 155Eu do not exceed the minimum detection limits of the method, which are 0.2 Bq/l for 241Am (intervention limit is 0.69 Bq/l), 0.30 Bq/l for 137Cs (intervention limit is 11 Bq/l), 0.24 Bq/l for 152Eu (intervention limit is 98 Bq/l), 1.1 Bq/l for 154Eu (intervention limit is 69 Bq/l) and 0.29 Bq/l for 155Eu (intervention limit is 430 Bq/l). As follows from Table 4, the contents of almost all studied radionu­ clides in the water samples of the Shagan River, regardless of the season, are much less than IL. The exception is tritium, the contents of which at the points 5, 6, 13 and 14, located near the “Atomic” Lake, are 1.2–1.3 times higher than the intervention limit (7600 Bq/l). Fig. 6 shows the distribution of the average seasonal activities of tritium in water, normalized by the intervention limit, along the Shagan River for the points where the activity values are above the minimum detection limit of the method. From the point of view of seasonal variations, there were no signif­ icant differences in the specific activities of tritium in the water samples of the Shagan River in different seasons of the year. The presence of large concentrations of tritium in the water and relatively high contents of 90Sr radionuclide at a distance up to 6 km from the “Atomic” lake indicates that their source of origin is not related to the inflow of contaminated surface waters. In this case, apparently, there is input of radionuclides with contaminated groundwater.

Fig. 4. Distribution along the Shagan River of the average seasonal contents of the second hazard class elements normalized by MAC.

Fig. 5. Distribution along the Shagan River of the average seasonal contents of the third hazard class elements normalized by MAC.

for other elements, is autumn since the average iron and manganese contents along the river are 241 μg/l and 115 μg/l, respectively. The most “contaminated” season is spring since the average iron and man­ ganese contents along the river are 604 μg/l and 247 μg/l, respectively. The highest iron contents are observed at the points 84 and 95 of the summer sampling with values of 990 μg/l and 820 μg/l, respectively. The highest manganese content 1200 μg/l is observed at the point 84 for the summer sampling. One of the reasons for high concentration of certain chemical ele­ ments in the water samples of the Shagan River may be the increased water salinity (mineralization). In this situation, the elements such as lithium and strontium may occur in significant concentration. The revealed areas with a sharp increase in the concentration of chemical elements (on average in 3 times) apparently indicate the inflow of elements from groundwater along the tectonic faults. In addition, the sharp rises and drops in manganese concentration probably have the natural origin, which is associated with the mechanisms of oxidative transformations, depending on various factors such as the pH and Eh of the environment, availability of the microorganisms capable to oxidize manganese, the values of dissolved oxygen, etc. Thus, the chemical composition of the water of the Shagan River can be explained by the local hydro-geochemical factors and the climatic conditions. 4.3. Radionuclide activity concentrations in Shagan water samples Earlier studies (Aidarkhanov et al., 2010) showed that the main radionuclide contaminants of the Shagan River are the artificial isotopes 137 Cs, 90Sr, 241Am, 152Eu, 154Eu, 155Eu, 3H, 239Pu and 240Pu. Among 7

I. Gorlachev et al.

Journal of Environmental Radioactivity xxx (xxxx) xxx

Table 4 Content of some artificial radionuclides in the water samples from the Shagan River. Sampling point

Pu-239 þ 240, mBq/l x�SD

Т-1 Т-2 Т-5 Т-6 Т-13 Т-14 Т-50 Т-51 Т-54 Т-55 Т-65 Т-66 Т-79 Т-80 Т-83 Т-84 Т-95 Т-96 Т-104 Т-106 Intervention level

0.31 � <0.22 0.38 � <0.22 0.37 � <0.22 <0.22 <0.22 <0.22 1.55 � <0.22 <0.22 0.56 � 0.43 � <0.22 0.57 � 0.47 � <0.22 0.46 � 0.35 � 550

Sr-90, mBq/l

H-3, Bq/l

Range

x�SD

Range

x�SD

Range

0.01

0.30–0.31

0.01

0.37–0.38

0.13

0.27–0.46

1.8

0.28–2.8

0.47 0.27

0.22–0.89 0.24–0.62 0.24–0.89 0.31–0.62

0.18 0.04

0.33–0.58 0.32–0.38

400–430 630–760 870–880 950–980 770–950 890–920 50–75 54–69 44–45 60–85 91–130 43–85 68–93 39–77 24–70 47–81 32–92 25–78 30–82 25–50

440 � 50 1900 � 800 10000 � 2000 11000 � 2000 9900 � 1600 9800 � 110 170 � 30 150 � 30 73 � 15 68 � 23 50 � 28 52 � 25 <13 <13 <13 <13 <13 <13 <13 <13 7600

400–500 1300–3000 8800–11000 8800–11000 8700–11000 9000–11000 140–200 130–180 60–90 45–90 <11-70 35–80

0.46 0.22

410 � 30 700 � 100 880 � 10 970 � 20 860 � 130 900 � 20 63 � 18 62 � 11 45 � 1 73 � 18 110 � 30 64 � 30 81 � 18 58 � 27 47 � 33 64 � 24 62 � 42 52 � 37 56 � 37 38 � 18 4900

Fig. 6. Distribution of the average seasonal activities of tritium in water, normalized to the intervention limit, along the Shagan River.

4.4. The possibility of using the water of the Shagan River for drinking purposes

where Сi is the average seasonal concentration of the i-th element, mg/l, MACi is the maximum acceptable concentration of the i-th element, mg/ l, n ¼ 10 is the number of analyzed elements of hazard classes 1 and 2 for which the seasonal average concentrations in the water samples exceed the minimum detection limits of the method.

In the regulatory literature (Sanitary and Epidemiological Re­ quirements for the Water Sources, 2012) it is recommended to use the following hygienic criteria for the quality of drinking water:

3. The presence of several radionuclides in drinking water is regulated by Equation (3) (Ionizing radiation and radia, 1999), as follows:

1. For heavy metals of 3 and 4 hazard classes, their content should not exceed MAC. 2. If several heavy metals of hazard classes 1 and 2 are found in drinking water, normalized by the sanitary-toxicological criterion of hazard, the heavy metal index (HMI) should not exceed 1. The index is calculated according to Equation (2) (Sanitary and Epidemiolog­ ical Requirements for the Water Sources, 2012), as follows: HMI ¼

n X Ci ; MACi i¼1

RI ¼

m X Aj ; IL j j¼1

(3)

where RI - radionuclide index, Aj – is the average seasonal activity of the j-th radionuclide, ILj is the intervention limit of the j-th radionuclide, m is the number of radionuclides (Table 4) which seasonal average activ­ ities in the water samples exceed the minimum detection limits of the method. As follows from Table 2, almost all points of sampling, there are

(2)

8

I. Gorlachev et al.

Journal of Environmental Radioactivity xxx (xxxx) xxx

elements of hazard class 3 with contents exceeding MAC. The exception is only point 5. Thus, at all sampling points except point 5, the first hygiene criterion for drinking water is not met. Figs. 7 and 8 show the distribution of heavy metal index and radionuclide index along the Shagan River. At all sampling points, the heavy metal index exceeds 1 and varies from 3.8 (point 1) to 9.1 (point 66). Thus, there are no sampling points for which the second hygienic criterion for drinking water quality is met. Finally, at points 5, 6, 13 and 14, the radionuclide index exceeds 1. At these points, the third hygienic criterion for the quality of drinking water is not met. Thus, in order for the water of the Shagan River to be used as drinking, it is necessary to carry out the following activities: 1. Purify water from chemical elements of hazard class 3 (Fe and Mn) at all points of sampling except point 5. 2. Purification water from chemical elements of hazard classes 1 and 2 (U, Li and Sr) at all points of sampling. 3. At sampling points 5, 6, 13 and 14, take measures to purify water from tritium, which is the main radionuclide contaminant in the collected samples.

Fig. 7. Distribution of the heavy metal index along the Shagan River.

5. Conclusion The performed studies established that the excess of the intervention limit for tritium in the water is observed in 4 points of the Shagan River only near the “Atomic” lake: the points T-5, T-6, T-13 and T-14. This excess is 20%–30%. In this case, apparently, there is input of radionu­ clides with the contaminated groundwater. At the same time, the excesses of the MAC values in water for heavy metals are observed for all sampling points with varying degrees. The high contents of uranium and lithium are especially alarming. Uranium as a chemical toxicant belongs to the first hazard class. Its maximum contents were revealed at points near the Atomic Lake and in the middle part of the Shagan River between points T-1 and T-55. When approaching the place of the Shagan River inflow into the Irtysh River, the uranium content decreases, but is close to the MAC value. The lithium contents exceed from 1.3 to 8.3 times the MAC value in water at all points of seasonal sampling. The situation is similar for iron, which average seasonal contents exceed the MAC value in water from 1.1 to 3.3 times except the points 1, 2 and 5. Exceedences of the MAC for strontium and manganese are observed only at some points. The data obtained confirm the initial assumption that at STS the water of the surface wa­ tercourses and the water supply objects are being more contaminated with heavy metals than with artificial radionuclides. One of the reasons for the high concentrations of lithium and strontium may be that the arid climate promoted the increase of salinity (mineralization) in the river water and eventually concentrated the el­ ements such as lithium and strontium significantly. Also the areas are revealed with a sharp increase in concentration of chemical elements on average 3 times, which may indicate the input of the elements with groundwater along the tectonic faults. The revealed sharp increases and decreases in the concentration of manganese in water, apparently, are of natural origin, which is associated with the mechanisms of oxidative transformations, depending on various factors - pH and Eh environment, the presence of microorganisms capable of oxidizing manganese, the values of dissolved oxygen, etc. Thus, the water chemical composition of the Shagan River is most likely explained by local hydro-geochemical factors and climatic conditions. The water of the Shagan River is not used by the local population as drinking water. However, livestock feed water from the river every­ where. This can lead to accumulation of heavy metals in the human body through the chain: water → animals → humans. Therefore, as a recommendation, it would be advisable for the local population to avoid watering animals in the most “contaminated” points, especially on ele­ ments of the first danger class (points T-5, T-6, T-13, T-14, T 50, T-54 and T-55). In addition, there are increased specific activities of tritium in

Fig. 8. Distribution of the radionuclide index along the Shagan River.

the points T-5, T-6, T-13 and T-14. Based on the data obtained, it can be concluded that in order to use the water of the Shagan River for drinking purposes, it is necessary to carry out the special measures to purify water from chemical elements of 1, 2 and 3 hazard classes and tritium. Funding The works were performed in the framework of the project K-2161 of the International Science and Technology Center. Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References Aidarkhanov, S., Lukashenko, S., Subbotin, S., Edomin, V., Genova, S., Toporova, A., Larionova, N., Pestov, E., 2010. Ecosystem of Shagan River and major mechanisms for its formation. In: Sergey, N., Lukashenko (Eds.), Proceedings of the Institute of Radiation Safety and Ecology for 2007e2009. Dom Pechati LLP" printing house, vol. 2, p. 9. Pavlodar. Issue. Aidarkhanov, A.O., Lukashenko, S.N., Lyakhova, O.N., Subbotin, S.B., Yakovenko, Yu Yu, Genova, S.V., Aidarkhanova, A.K., 2013. Mechanisms for surface contamination of soils and bottom sediments in the Shagan River zone within former Semipalatinsk Nuclear Test Site. J. Environ. Radioact. 124, 163–170. Burlibaeva, M. Zh (Ed.), 2012. Methodological Recommendations on the Complex Assessment of Surface Water Quality According to Hydro-Chemical Indicators, p. 80. Astana. Hygienic Standards, 03.02.2012. Sanitary-Epidemiological Requirements for Provision of Radiation Safety. the Government of the Republic of Kazakhstan. Approved by the Resolution No. 201 Issued on.

9

I. Gorlachev et al.

Journal of Environmental Radioactivity xxx (xxxx) xxx M., Tonevitskaya, O.V., Toporova, A.V., 2012. Materials of the Comprehensive Ecological Survey of “Western” Part of the Semipalatinsk Nuclear Test Site. Panin, M., September, 2003. Heavy metals and their forms in the soils of former Semipalatinsk nuclear test site. NNC RK Bull. Issue 3, 107. Panitskiy, A.V., Lukashenko, S.N., 2015. Nature of radioactive contamination of components of ecosystems of streamflows from tunnels of Degelen massif. J. Environ. Radioact. 144, 32–40. Sanitary and Epidemiological Requirements for the Water Sources, the Sites of Water Supply for Household and Drinking Purposes and the Places of Cultural and Community Water Use and Safety of Water Objects, January 18, 2012. Government of the Republic of Kazakhstan. Approved by the Resolution No. 104 Dated. SanPiN 3.02.002.04 Sanitary and Epidemiological Requirements for the Quality of Water in the Centralized System of Drinking Water Supply, June 28, 2004. Acting Minister of Health of the Republic of Kazakhstan. Approved by the Order No. 506 Dated. Seither, A., Eide, P., Berg, T., Frengstad, B., 2012. The inorganic drinking water quality of some ground water works and wells in Norway. Report N� 2012.073 Geol. Surv. Norway. NGU Report 2012, ISSN 0800-3416. Tashekova, A., Lukashenko, S., Koigeldinova, M., Mukhamediyarov, N., 2016. Characteristics of Shagan river element composition. Bulletin of the Krasnoyarsk State Agrarian University, Krasnoyarsk, p. 141. Yakimenko, A.N., 2013. Estimation of water quality of the Kiev reservoir by indices of radiation safety. J. Water Chem. Technol. 35 (No. 4), 189–193. Yamamoto, M., Tomita, J., Sakaguchi, A., Ohtsuka, Y., Hoshi, M., Apsalikov, K.N., 2010. Uranium isotopes in well water samples as drinking sources in some settlements around the Semipalatinsk Nuclear Test Site, Kazakhstan. J. Radioanal. Nucl. Chem. 284, 309–314. https://doi.org/10.1007/s10967-010-0463-2.

IAEA, 1998. Radiological conditions at the Semipalatinsk Test Site, Kazakhstan: preliminary assessment and recommendations for further study (STI/PUB/1063). Retrieved. http://www-pub.iaea.org/MTCD/Publications/PDF/Pub1063_web.pdf. (Accessed 20 October 2013). ICRP, 1991. 1990 recommendations of the international commission on radiological protection. Publication 60. Ann. ICRP 21, 1–3. Ionizing Radiation, Radiation Safety. Radiation Safety Standards (NRB-99), 1999. Ministry of Health of the Russian Federation. SP 2.6.1.758-99. M. Kadyrzhanov, K.K., Khazhekber, S., Solodukhin, V.P., Lukashenko, S.N., Kazachevskiy, V., Rofer, Ch, Poznyak, V.L., Knyazev, B.B., et al., 2005. Plutonium at the Semipalatinsk nuclear test site (SNTS). J. Radioanal. Nucl. Chem. 263 (1), 229–234. https://doi.org/10.1007/s10967-005-0041-1. Lukashenko, S.N., Artemyev, O.I., Kashirskiy, V.V., Strilchuk, Yu G., Subbotin, S.B., Ossintsev, A. Yu, Panitskiy, A.V., Larionova, N.V., Magasheva, R. Yu, Yakovenko, Yu Yu, Korovina, O. Yu, Bakirov, R.M., Tonevitskaya, O.V., Toporova, A.V., Cheredov, O.I., 2010. Topical Issues in Radioecology of Kazakhstan (1), 234. Semipalatinsk Test Site: Radioecological Situation in the “Northern” Lands. Lukashenko, S.N., Strilchuk, YuG., Ossintsev, A. Yu, Subbotin, S.B., Kashirsky, V.V., Panitskiy, A.V., Larionova, N.V., Magasheva, R. Yu, Yakovenko, Yu Yu, Korovina, O. Yu, Bakirov, R.M., Tonevitskaya, O.V., Toporova, A.V., Kunduzbaeva, A.E., Lyakhova, O.N., Aidarkhanov, A.O., Sultanova, B.M., Bakhtin, L.V., Gluschenko, V. N., 2012. Materials of the Comprehensive Ecological Survey of “South-Eastern” Part of the Semipalatinsk Nuclear Test Site. Lukashenko, S.N., Subbotin, S.B., Ossintsev, A. Yu, Kashirsky, V.V., Panitskiy, A.V., Larionova, N.V., Magasheva, R. Yu, Yakovenko, Yu Yu, Korovina, O. Yu, Bakirov, R.

10