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Uranium and Fluoride geochemical pathways in Ulaanbaatar and rural Mongolia

Robin Grayson, Baatar Tumenbayar, Daramsenge Luvsanvandan and Amarsaikhan Lkhamsuren

blue sky of Mongolia

combustion of uraniferous coal

photochemical smog blanketing the city

uraniferous ash settling over the city

uraniferous ash settling in lagoons

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Uranium and Fluoride geochemical pathways in Ulaanbaatar and rural Mongolia

Robin Graysona1, Baatar Tumenbayarb, Daramsenge Luvsanvandanc and Amarsaikhan Lkhamsurend

a Independent consultant, Manchester, United Kingdom b Sans Frontiere Progres NGO, Sukhbaatar district, Ulaanbaatar, Mongolia c Academician of National Academy of Science of Mongolia d Environmental consultant, Mongolia Abstract Explanation is sought for the high uranium levels in Ulaanbaatar’s ash dumps, groundwater, construction materials and vegetation, and the high radon level in the city’s drinking water. Combustion of uranium-bearing coals is a cause, but natural sources of uranium may also be factors. Mongolian coals are important sinks for elemental enrichment by uranium and other heavy metals, and 24 Mesozoic, Permian and Carboniferous coals have U-content above 1 g/tonne. Coal ash wastes are U-enriched due to depletion of volatiles and are candidates for economic extraction of uranium and other valuable metals. Uranium in water often exceeds WHO drinking water guidelines and chronic poisoning or fatality of aquatic crustaceans is probable. The uranium concentration in some ash dumps is sufficient to envisage economic recovery through in-situ leaching. While coals and ash are ‘U-sinks’, over 2,000 soda lakes and sodic soils are ‘U-drivers’ causing thousands of square kilometres of Mongolia to have elevated uranium levels, and the cause of elevated levels of fluoride, arsenic, selenium and other elements. Soda lakes and their remarkable ecosystems merit scientific study. The uranium concentration in some soda lakes is sufficient to envisage economic recovery by mining. Sulphate-reducing alkali extremophile bacteria are capable of reducing uranium (VI) to precipitate uranium (IV) oxide (UO2) as uraninite, while nitrate-reducing alkali extremophile bacteria can dissolve the uraninite into U (VI) solution. The soda lakes’ integrity depends on large-scale removal of calcium ions, sequestrated as hundreds of millions of tonnes of Ca- carbonates locked on the undersides of gravel clasts. Calcium depletion permits leaching of fluorspar veins across vast regions, and the elevated fluoride levels of well waters causes thousands of rural children to suffer from endemic dental fluorosis. Blanket surveys for dental fluorosis are warranted in all fluorspar districts. Leaching of arsenic and mobilisation in sodic waters causes thousands of people to suffer from endemic arsenic poisoning. Environmental regulations should require coal projects to publish analyses of U, F, As, Se of coals, ash and leachates, and for all uranium projects to publish water analyses of wells in their watersheds.

1Corresponding author. Manchester, United Kingdom. E-mail address: [email protected] 3

1 Introduction

Until recently Mongolia had the world’s fastest growing economy with a 17.3% rise in GDP in 2011 driven by a mining boom (World Bank, 2012). Uranium mining may commence soon, exploiting conventional uranium resources amenable to low-cost open pit mining and in situ leaching. This review focuses on unconventional uranium resources, such as surface water, groundwater, soil, coal, ash and vegetation. None are current exploration targets but this may change suddenly if new technology cuts extraction costs. Uranium is more widespread in Mongolia than hitherto realised, and this study organises fragmentary data in to predictive geochemical models able to give insight into exploration, mining, environment and health. In doing so, the study sheds light on dental fluorosis being endemic in Gobi communities, and on radon emanation in the capital city. Priorities are to explain elevated uranium levels in Ulaanbaatar’s groundwater, coal supplies, construction materials and vegetation; the high levels of radon in Ulaanbaatar’s tap- water, and the high uranium levels in some springs and soda lakes. 2 Mongolia’s uranium industry 2.1 Soviet investment In Soviet times, Mongolia enjoyed a boom in mineral exploration and mining. The boom collapsed with the fall of the Soviet system and many mines closed half-finished. Mongolia de- industrialised more completely than any other nation (Reinhert, 2003). Total economic collapse was averted by exports from two mines of strategic interest to Russia: copper/molybdenum concentrates from and fluorspar concentrates from Bor Undor. Sufficient coal mines remained open to maintain the electricity grid and district heating essential to Ulaanbaatar – the world’s coldest capital city, the average annual mean temperature being-0.9°C and winter temperatures being often as low as 25-38°C (Batima, 2003). 2.2 Subsequent revival Deprived of Russian roubles and markets, the Mongolian uranium industry closed. To avert national collapse, the gold industry was liberalised by the Government’s Gold Program. Gold output soared when the vast archive of Soviet placer gold drilling became open-file and licences became available and cheap. Over 130 placer gold companies produced 11 tonnes of gold a year and spun out over 1,000 enterprises across all sectors (Grayson and Tumenbayar, 2005). Meanwhile the uranium industry disintegrated and largely disappeared. Its archives of once- secret reports were now public but aroused scant interest due to the low uranium price. Meanwhile Soviet reports on coal, oil, copper, molybdenum, iron ore, titanium sands, tin, zinc, fluorspar and phosphates triggered boom after boom across commodity after commodity. Inward investment soared and mineral exports climbed to record levels. Informal mining boomed, notably artisanal gold mining employing over 100,000 people (Grayson, 2007). In spite of 40 years’ effort, uranium contributes nothing to the Mongolian export trade having become a strategic asset mired in state intervention, leading to disputes and uncertainty eroding investor confidence and delaying investment. 4

2.3 Vision of nuclear power

Mongolian GDP will rise further, fuelled by the world-class Oyu Tolgoi copper mine; followed by the huge Tavan Tolgoi coal mine. These will boost Government finances enabling the State policy for nuclear power to be part of Mongolia’s mix of energy self-sufficiency. Already a 300-500 kW TRIGA nuclear research reactor with 1012−13 n/cm2 s neutron flux has been selected for use “in various studies and for educational and training purposes” (Sambuu et al., 2011). The second reactor is planned to be a modular nuclear reactor to supply district heating in Ulaanbaatar. A joint design study has been completed by the Nuclear Research Centre of the National University of Mongolia and the Research Laboratory for Nuclear Reactors of the Tokyo Institute of Technology (Sambuu and Obaraa, 2012). The chosen design is a high temperature gas-cooled reactor (HTGR) with passive safety features for long core life. The reactor core is 8 metres wide and 8 metres tall, and will generate 330 MWth of power. Ulaanbaatar’s district heating is supplied by superheated steam from city-based combined heat and power plants CHP #2, 3 and 4, with CHP #5 being planned (HJI and MonEnergy Consult, 2011). All burn unwashed low quality brown coal, contributing to very poor air quality in winter (World Bank, 2012).But two-thirds of the city residents lack district heating, living in ‘ger districts’ and burn coal, wood, paper, card, plastic, tyres and waste oil. This, plus emissions from CHP #2, 3 and 4, make Ulaanbaatar the world’s most polluted capital city in winter (World Bank, 2011).The outdoor air pollution was estimated by Allen et al. (2011) to cause early deaths of 623 residents a year; a figure higher than the deaths due to suicides, murders and transport accidents. Accordingly a strong case can be made for nuclear power to replace coal for district heating. Released from its district heating role, coal can be burned at distant mine sites to generate electricity for the ‘clean air’ Ulaanbaatar. Other benefits include cutting coal trains so freeing rail slots for mineral exports; cutting industrial consumption of groundwater that is Ulaanbaatar’s only source of water; and eliminating ash that is a serious health risk contributing not only to city air pollution but also to indoor radon pollution from ash used in construction materials. However, a wider role for nuclear energy is difficult to justify, albeit offering clean energy with minimal greenhouse gas emissions. Mongolia has enormous resources of coal, oil, solar and wind energy. Wind energy alone is sufficient to meet 40% of China's energy demand by 2030 (Borgford-Parnel, 2011) and is already a world leader in wind energy, so expanding the ‘wind grid’ into Mongolia would allow Mongolia to become net carbon neutral while exporting electricity to China.

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3 Conventional uranium resources 3.1 Distribution of conventional uranium resources

Mongolia has significant conventional uranium resources, mostly in the south, south-east and east. None are reported from the western regions (Fig.1).

Figure1 Regional interpretation of conventional uranium resources, adapted from a recent summary by Tserenpurev and Manlaijav (2011).

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3.2 Conventional uranium deposits and occurrences documented by Soviets

Soviet geologists discovered 77 uranium localities and ranked 70 as ‘occurrences’ and 7 as ‘deposits’, of which 52 were subject to intense scrutiny and awarded ‘passports’. The Soviet archives are public (Dejidmaa et al., 2001) and are the culmination of uranium exploration efforts that at 2012 prices would cost several billion US dollars (Tables 1 and 2). Table 1 Sedimentary and stratiform uranium deposits and occurrences in State Geofund.

Reference Passport CONVENTIONAL URANIUM DEPOSITS AND OCCURENCES Map Sedimentary and Stratiform Dejidmaa major minor name et al. (2001) status

commodity commodity latitude longitude Sandstone-hosted Uranium 11 P Elgen 43 50 00 108 58 00 U - 13 P Khad 43 46 00 108 58 00 U - K49 14 P Ail 43 44 00 108 55 00 U - 23 P Gulon 43 47 00 109 02 00 U - 27 P Taj 43 31 00 109 28 00 U - Noyon U - 32 P 43 08 00 108 30 00 occurrence 312 P Naidal 703 47 09 25 107 56 50 U - 479 - Osh Nuur 44 50 40 102 00 38 U-Th P 559 - Oin Gol 44 22 21 102 01 33 U-Th P 200 - Ikh Bulag 46 57 00 112 56 00 U - 219 P Shivee Ovoo 46 13 00 108 32 00 U - 267 P Shand Bulag 46 37 00 111 55 00 U - 275 P Olziit 46 24 00 111 36 00 U Deposit V, Mo, Ce 275 P Olziit 46 24 00 111 36 00 U V, Mo, Ce 299 P Ereen-1 45 50 00 108 29 00 U occurrence - L49 310 - Anomaly 12 45 44 10 108 31 30 U - 317 P Kharaat 45 38 10 108 21 30 U deposit - Khavtsal U - 353 P 45 32 42 109 07 80 occurrence 405 P Yant 44 48 00 109 26 00 U - 408 P Narst 44 55 00 110 33 00 U deposit V, La, Ge 409 - Narst 44 53 00 110 19 00 U - 420 P Dorvoljin 44 59 20 111 07 20 U - 446 P Tolgoi 513 44 15 00 109 36 00 U - 447 P Baruun 44 14 00 109 51 00 U occurrence - 448 P Dulaan Khar 44 04 00 109 45 00 U - M46 360 P occurrence 777 48 36 00 92 17 00 U P Sediment-hosted Uranium M50 98 P Shinebulag 48 44 00 114 10 00 U occurrence - Sedimentary Stratiform Uranium-Vanadium 82 P Mongosh 50 37 00 99 24 00 V - 83 - Tsohyn 50 36 00 99 19 00 V Cu, As M47 195 P Khitagiin Gol 18 49 49 00 99 50 00 V occurrence U, Mo 196 P Thahiruul 21 49 46 20 99 53 25 V U, P 198 P Buyant 83 49 44 00 99 47 00 V U

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Table 2 Igneous-hosted uranium deposits and occurrences in State Geofund.

Reference Passport CONVENTIONAL URANIUM DEPOSITS AND OCCURENCES

Map Igneous Hosted Dejidmaa name et al. (2001) major status minor

commodity commodity latitude longitude Volcanic-hosted Uranium 480 P Olziit 44 45 38 102 00 05 U-Th Sr, Mo, P L48 523 P 45 06 00 106 54 00 U - 582 - Teeg Uul 44 16 00 104 08 30 U - 88 - Tanai 201-203 47 57 00 111 34 00 U occurrence - 144 P Narangiin Bulag 47 04 20 108 00 00 U - 151 P Moron 47 09 00 109 50 00 U Pb 222 - Khar Tolgoi 46 04 00 108 45 00 U - L49 233 - Borondor 46 18 00 109 24 00 U - 239 - Ikh Khet Deposit 46 13 00 109 50 00 U deposit - 239 - Ikh Khet Occur. 46 13 00 109 50 00 U - 342 P Khongor-2 45 48 00 109 02 00 U - 354 - Ulaan Nuur 45 32 00 109 30 00 U occurrence - L50 33 P unnamed 38 46 52 00 115 12 00 U - 185 - Gurvanbulag 49 02 00 113 56 00 U deposit Mo M49 298 P Mizornoe 48 16 00 111 53 00 U - occurrence 304 P Ikh Bulag 48 04 00 111 32 00 U - 72 - Dornod-1 (Mardai) 49 10 00 114 25 30 U - deposit 73 - Dornod-2 (Mardai) 49 08 00 114 29 00 U 81 P Ilreh 49 08 00 114 19 00 U - 82 P Tsever 49 07 00 114 15 00 U - M50 84 P Davaa 49 04 00 114 03 22 U - 88 - unnamed 49 05 00 114 13 00 U occurrence - 89 P Khar 49 04 00 114 22 00 U - 92 - unnamed 49 00 00 114 02 00 U - 97 P Delger Nuur 48 51 00 114 23 00 U Pb, Zn Granitoid-related Uranium 165 P Elst 1308 47 42 00 107 37 00 U - 166 P Arshaan 1309 47 40 00 107 36 00 U - L48 167 P Tamga 376 47 39 00 107 41 00 U - 168 P Urt 376 47 39 00 107 37 00 U - 459 - Khavirga Khudag-I 45 58 00 107 44 00 U-Th - 460 - Khavirga Khudag-II 45 56 00 107 45 00 U-Th occurrence - L49 177 - Baruuntsogt 46 44 00 111 44 00 U - L50 74 P Tsagaanuul 46 02 35 115 56 12 U, Mo - M46 76 P Goojuur 244 49 26 30 91 16 02 U - M48 134 P Tsushiin Gol 49 46 00 104 39 00 U - Th(U)-Nb-Zr(REE) alkaline metasomatites 99 P Khashaatyn Khar 49 31 02 92 35 36 Zr Nb, Th M46 250 P Occurrence A-681 48 53 00 94 57 00 Nb Zr, Th 251 P Occurrence A-683 48 52 00 94 48 00 Nb Ta, Th 85 - Ar Gol 50 28 20 99 53 55 Th, Nb, Zr T R, U 96 - Ujig Gol 50 15 40 99 46 43 Th, Nb, occurrence Zr TR, U M47 98 - Khagiin Nuur 50 16 00 99 37 00 Th, Nb, Zr TR, U 104 P Alag Ergene 50 05 00 99 54 10 U 133 P Yarhis Gol 50 16 50 100 23 30 U, Th, Zr Nb, Mo M48 125 - Bayangol 2201/2/3 49 30 36 103 39 36 U-Th - Ta-Nb-(REE) pegmatite M48 124 - Bayangol 415 49 31 00 103 35 25 Ta, Nb REE occurrence Zr, U, Th Post-Soviet uranium exploration and development efforts have focussed on confirming and expanding Soviet-discovered localities and redefining Soviet-estimated resources into western categories. Stock markets now ensure release of drilling results and NI-43-10 reports, but reports submitted by unlisted private companies and state-controlled uranium companies, such as AREVA of France, have not been released by the Government. 8

3.3 Conventional uranium deposits ready to mine

Conventional uranium deposits are monographed by Dahlkamp (2009). Mongolia ranks 15th in the world with 37,500 tonnes of uranium in Reasonably Assured Resources plus 11,800 tonnes of Inferred Resources (OECD/IAEA, 2010). All of these resources are in volcanic and sandstone-hosted uranium deposits that are amenable to low-cost open pit mining and in situ leaching (Table 3).

Table 3 Conventional resources of uranium in Mongolia ready for mining. Adapted from WISE (2011) and WNA (2012). Reserves NI-43-10 Resources area deposit Host rock proven probable compliant measured indicated inferred Gurvan- 7,612 t U 2,236 t U Hairhan sandstone yes Saihan 0.062% U 0.040% U Gurvan- 2,461 t U Haarat sandstone yes Saihan 0.023% U Gurvanbulag Gurvanbulag 1,538 t U 5,346 t U 1,577 t U 5,308 t U 846 t U Saddle Hills volcanic yes Project Central 0.17% U 0.13% U 0.21% U 0.15% U 0.11% U 24,731 t U 923 t U Mardai Dornod-Uran volcanic yes 0.10% U 0.042% U Dornogobi 9,888 t U Dulaan Uul sandstone ? aimag 0.017% U TOTALS: 1,538 t U 5,346 t U 1,557 t U 25,651 t U 16,354 t U

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4 Unconventional uranium resources – coal and coal ash

Unconventional uranium resources, such as uraniferous coal, uraniferous ash, construction materials, soils, soda lakes, groundwater, surface waters, vegetation, and air, are widespread in Mongolia. These resources are sub-economic but this could change if the world uranium price rises sufficient to warrant attention by mining companies and justify research in extraction technology. 4.1 Uraniferous coals

Trace amounts of uranium are found in coals worldwide. However there is no global consensus about what level of uranium justifies labelling a particular coal as “uraniferous”. To put the issue in context, it has been suggested by the International Atomic Energy Authority that: "It is evident that even at 1 part per million (ppm) U in coal, there is more energy in the contained uranium (if it were to be used in a fast neutron reactor) than in the coal itself. If coal had 25 ppm uranium and that uranium was used simply in a conventional reactor, it would yield half as much thermal energy as the coal.”(IAEA, 2003). For consistency within Mongolia we arbitrarily define “uraniferous coals” as coals having a minimum uranium content of 1 ppm (1 gram U per tonne), and “uraniferous ash” as ash having a minimum uranium content of 5 ppm (5 gram U per tonne). Mongolia’s U-bearing coals are considered by Arbuzov et al. (2011) to be part of a vast tract of U-bearing coals extending across northern Asia. They attribute the presence of uranium and thorium to active volcanism contemporaneous with peat accumulation, and report that the U content of more than 5,000 coal samples range from 0.6 to 32.8 ppm. However the uranium content of some Mongolian uraniferous coals locally exceeds 1,000 ppm (Gow and Pool, 2007). Many coals of north-central Mongolia are exceptionally radioactive, and Dejidmaa et al. (2001) listed 15 uraniferous coals in Soviet archives in the Mongolian State Geofund. Dugarjav (2005) and Luvsanvandan (2012 MS) listed a further 9 uraniferous coals. It is likely that the total number will be much higher (Table 4).

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Table 4 Unconventional uranium resources Mongolian coals and coal ash. UNCONVENTIONAL URANIUM DEPOSITS AND OCCURENCES

Reference

Passport

Dugarav (2005) Uraniferous Coal Luvsanvandan

(2012 MS) Map Dejidmaa et al. (2001) Coal name major status minor Ash

commodity commodity

latitude longitude

Uraniferous Jurassic-Cretaceous Coals 702 P 47 44 50 107 17 0 Brown Coal U 1 g/t U 7 g/t U  L48 825 P Tevshiin Govi 45 59 59 105 59 59 Brown Coal - 1 g/t U 5 g/t U  937 - Talyn Bulag 45 43 00 106 6 00 Brown Coal - 4 g/t U 20 g/t U  131 P Sharyn Gol 46 10 10 108 27 34 Brown Coal deposit - 3 g/t U 22 g/t U  7 g/t U 29 g/t U  459 P 47 44 00 108 23 00 Brown Coal U 4.1 g/t U 22 g/t U  482 P Chandgana 47 23 15 110 01 00 Brown Coal - <1 g/t U <5 g/t U  584 P Shivee Ovoo 46 10 10 108 27 34 Brown Coal U 5.1 g/t U 7.9 g/y U  L49 586 P Nogoon Toirom 46 06 00 108 38 00 Brown Coal occurrence U - - 601 P Alag Togoo 46 10 30 109 02 20 Brown Coal - 4.5 g/t U 18 g/t U  deposit 627 P Uelziit 46 24 00 111 36 00 Brown Coal U - 630 P Khalzan Ovoo 46 15 00 111 24 00 Brown Coal U - 653 P Ereen Soum-1 45 51 00 108 29 00 Brown Coal U - 654 P Ereen Soum-2 45 51 00 108 31 00 Brown Coal U - occurrence 120 P Bayan Us 47 50 30 115 35 30 Brown Coal U - 122 P Us Nuur 47 47 00 115 33 00 Brown Coal U - 147 P Arjar Oelziit 47 13 00 114 46 00 Brown Coal U - L50 151 P Hoeot 46 58 00 114 30 00 Brown Coal U - deposit 164 P Zuen Bulag 46 57 00 115 17 30 Brown Coal U - Nuur Hooronduin 166 P 46 52 00 115 32 00 Brown Coal occurrence U - Heseg M46 447 P Khar tarvagatai 49 32 48 91 40 45 Black Coal deposit - 2 g/t U 15 g/t U  M50 207 P Aduunchuluun 48 08 06 114 31 30 Brown Coal deposit U, Ge 66 g/t U 300 g/t U  Uraniferous Permian Coals 2 g/t U 10 g/t U  K48 116 P Tavan Tolgoi 43 37 00 105 28 30 Black Coal deposit - 1.1 g/t U 6.4 g/t U  Uraniferous Carboniferous Coals L46 430 P Olonbulag 45 10 00 91 18 00 Black Coal - 1 g/t U 5 g/t U  deposit L47 429 P Bayanteeg 45 42 00 101 34 00 Black Coal - 4 g/t U 20 g/t U  Plotting the locations of uraniferous coals on Google Earth shows that several are now large open pit coal mines, including the main suppliers to combined heat and power (CHP) plants of the cities of Ulaanbaatar, , Erdenet and , which several have begun exporting coal to China and Russia. 4.1.1 Uraniferous coals in Ulaanbaatar, the capital city Ulaanbaatar depends on coal for heating and electricity. Coals entering the city are unwashed Cretaceous brown coals (lignites) of low calorific value, and all were termed ‘uraniferous coals’ in Soviet reports. The city power plants were supplied by rail with unwashed U-bearing coals from the Nalaikh underground mine (47°45'2"N 107°16'40"E) in Nailakh, a satellite town on the eastern side of the city. Since mine closure in the 1990s, two dozen licensed small coal mines and over 100 informal unlicensed mines supply unwashed U-bearing coal by truck to the ger areas and small heating plants in the capital city (Grayson, 2003). The Baganuur Mine (47°44'30"N 108°18'50"E) became the main rail supplier of U-bearing coals to the capital’s combined heat and power (CHP) plants (Fig. 2) and continues to be so, joined by trainloads of U-bearing coal from the Shivee Ovoo Mine (46°13'30"N 108°18.50"E). 11

Figure 2 Panorama of Ulaanbaatar in winter, showing discharge of vapour and ash from the stacks of CHP No.3 that burns only uraniferous coal. In the background is the thick layer of photochemical smog that blankets much of the city throughout the winter. Photo: Nick Grayson. Baganuur and Shivee Ovoo coals were studied by Dill et al. (2004), Altangerel et al. (2009) and Maslov et al. (2010). The uraniferous character was clarified by HJI and MonConsult (2009) assessing radionuclide activity, as presented in Table5. Table 5 Radionuclide activity of the Baganuur and Shivee-Ovoo Coals. Isotope Activity (Bq/kg) Radium 228 232 40 Equivalent Ra Th K (Bq/kg Baganuur Coal 27 3 <29.4 28.3 Shivee-Ovoo Coal 19 6 - 23.8 Altangerel, Norov and Altangerel (2009) investigated Baganuur coal and soil samples and measured226 Ra, 232 Th and 40K activity by gamma-ray spectrometry, and confirmed the high content of natural radionuclide elements (U, Th and K).Dill et al. (2004) made a geological and geochemical assessment of Baganuur and concluded “migration of calcium, uranium and strontium into the siliclastic interseam sediments had been facilitated by post-depositional alteration of these sediments being “favoured by a distinctive facies association of transmissive and sealing horizons”. The orthodox view would be that the uranium originated from penecontemporaneous vitrioclastic debris in tephra falls. We prefer a simpler explanation that from the Neogene to the present day alkaline sodic groundwater has leached volcanic-hosted uranium in the horst bounding the north margin of the Baganuur Basin. 4.1.2 Uraniferous coals associated with sandstone-hosted uranium Exploration for sandstone-hosted uranium often discovers U-bearing coals in association. This relationship is evident with “accessory” uranium resources (see Table 4) and more definitively by recent drilling of sandstone-hosted uranium targets (Fig. 3) that encounters U- bearing coals in the same package of sediments (Gow and Pool, 2007).As in-situ leach mining is only considered for U-bearing sandstone, the U-bearing coal and U-bearing claystones are excluded from the estimated uranium resource.

Figure3 Hairhan Uranium Deposit, Mongolia. Conventional uranium resources in sandstone associated with unconventional resources in coal and claystones. Adapted from: NI 43-101 Report prepared for Denison Mines Corp. by Scott Wilson Roscoe Postle Associates Inc. (redrawn from Gow and Pool, 2007)

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4.2 Uraniferous ash from coal wildfires 4.2.1 Ancient coal wildfires – paleofires Many coals in the geological record contain evidence such as fossil charcoal and fusain of peat wildfires during peat accumulation (Pausas and Keeley, 2009). In addition, the geological record shows many wildfires in coal itself (e.g. Zhang et al. 2004). If the parent coal was uranium-bearing then residual ash, clinker and coke would be expected to have a uranium content elevated two to five times due to loss of combustibles. Evidence for such a paleofire exists in the Tavan Tolgoi Coalfield as the combusted remains of a Late Permian coal. Reddish “anthracite” reported by Gankhuyag and Eviikhuu (1999) at Tavan Tolgoi (43°36'N 105°28'E) is probably residual coke from a long-extinguished paleofire. It is tempting to attribute the coke to wildfires during Late Permian times as described in eastern Yunnan by Shao et al. (2012), and reported globally as a contributory factor to the mass extinction associated with the Permian-Triassic boundary. But a Neogene-Quaternary age is preferred as the coke has the form of a residual deposit related to the modern ground surface, is fault- bounded on one side and drilling proved intact coal in all directions. The coke may be a product of repeated wildfires, as were Jurassic coals in during Pliocene to Early Quaternary, Middle Pleistocene, Late Pleistocene and Holocene times (Zhang et al., 2004). 4.2.2 Wildfires in virgin uraniferous coal Mongolia has few instances of active wildfires in virgin coal. Unconfirmed reports exist for small areas near Tavan Tolgoi, Nariin Sukhait and Ukhaa Khudag in the (Grayson and Baatar, 2009), sometimes with U-bearing coals. In contrast, active wildfires in virgin coals are common in Inner Mongolia and Xinjiang (Kuenzer et al., 2007). 4.2.3 Wildfires associated with coal mining Evidence of active, dormant or recently extinguished wildfires are common in Mongolia’s Jurassic and Cretaceous coals and occasionally in Permian and Triassic coals. Evidence for coal wildfires is apparent in the open pits and dumps of Sharin Gol Mine, Baganuur Mine, Shivee Ovoo Mine and Chandaltal Mine, and reports of active coal wildfires at Aduunchuluun Mine and elsewhere. Thermal metamorphism by wildfires produces ash, clinker and tough hornfels known as ‘burnt red shale’ that is equivalent to fired brick. All these coals are uraniferous and therefore ash and ‘burnt red shale’ is expected to have elevated uranium levels.

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4.3 Uraniferous ash from coal burning 4.3.1 Coal ash from domestic heating In Ulaanbaatar half the population live in 175,000 households in ger districts, dominated by the traditional felt tent. Coal is the main fuel for cooking and heating, but competes with wood faggots, rubber, plastic, paper and old engine oil. The coal is uraniferous and trucked from small mines in Nalaikh and distant mines such as , Baganuur and Shivee Ovoo. At Nalaikh, about 20 licensed small mines and over a hundred informal mines operate seasonally to meet the winter peak demand for heating (Grayson, 2003, Grayson and Baatar, 2009). Loss of combustibles and volatiles from coal during burning render the ashes more uraniferous. In winter, ‘cinders’ and fine ash are shovelled out of the ger several times a day, and spread over the ground. Fine ashes and hot gases vent from the fire via the central metal pipe stack. In winter, more than half the urban households handle bags and buckets of U- bearing coal, shovelfuls of U-bearing ash, and breathe U-bearing ash dust, suggesting a daily risk of uranium chemotoxicity to the human body, via food, water, lungs, skin and clothes. Indoors the airborne mix of fine ash, soot and sticky hydrocarbons may facilitate settling in the lungs of carcinogenic daughter isotopes of radon. 4.3.2 Coal ash from combined heat and power plants Radionuclides in coal ash from combustion of Baganuur coal at CHP #3 were determined by Altangerel et al. (2009). Levels are sufficient to suggest the ash is unsuitable for most construction uses. Nevertheless ashes from CHP #2, #3 and #4 are used extensively as construction materials in Ulaanbaatar. Maslov et al. (2010a,b) tested bottom ash waste (BAW) from Baganuur type B3 brown coal, with an ash content, of 12% burnt in CHP #4 (Table 6). Table 6 238U, 226Ra, and 232Th nuclides in bottom ash waste from Baganuur coal. Data adapted from Maslov et al. (2010a, b). nuclide Samples min ppm max ppm average ppm 238U 10.6 154.0 54.3 232Th 144 1.8 21.9 12.4 226Ra 3.5×10–6 5.1×10–5 1.8×10–5 Ashes from Baganuur and Shivee Ovoo coals are uraniferous (Altangerel et al., 2009, Batmunkh et al., 2007 and Maslov et al., 2010a,b).Data assembled by HJI and MonConsult (2009) allows the increase in radionuclide activity between the parent coals and ashes to be calculated (Table7).

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Table 7 Ratio of 228Ra:232Th:40K activity of Baganuur and Shivee Ovoo ash, and the increase in activity from that of the parent coals. Data adapted from HJI and MonConsult (2009). Radium Rank coal ash 228Ra increase 232Th increase 40K increase Equivalent increase Bq/kg 1 CHP4 Shivee Ovoo ash 267 x 14.05 142 x 23.67 268 468 x 19.66 2 CHP4 Baganuur ash 168 x 6.22 61 x 20.33 268 x 9.12 268 x 9.47 3 CHP4 Baganuur slag 145 x 5.37 39 x 13.00 229 x 7.79 214 x 7.56

4 CHP3 ash and slag 135 38 228 Regarding the radon health risk, HJI and MonConsult (2009) conclude Baganuur ash “can be used as construction materials for any purposes without restrictions”, and Shivee-Ovoo ash “can be mixed with other construction materials, such as local soil, and then can be used as construction material”. On the contrary, the wide variations in radionuclide activity in each ash were not assessed. This and the difficulty of policing, testing and blending on an hourly basis preclude Baganuur and Shivee-Ovoo ash for use in construction materials. Otherwise it cannot be certain the construction materials will conform to the Mongolian regulatory limit of 370 Bq/kg when used for “living house, all kinds of public buildings”. This limit should be lowered, being based on 33-year old guidelines of the NEA-OECD (1979) since when WHO guidelines for radon health risk have been tightened considerably. 4.3.3 Coal ash from heat-only boilers Ulaanbaatar has about 800 heat-only coal-fired boilers (Guttikunda, 2007) that stay active throughout winter to prevent damage to buildings and contents. The main fuel is U-bearing coal from Nalaikh, Bagakhangai, Baganuur and Shivee Ovoo. Fine U-bearing ash is vented with smoke to the atmosphere while coarse ash (clinker and cinders) is spread out on the ground. Uranium levels in soils are therefore predicted to rise significantly each winter. 4.3.4 Coal ash from brick production Ulaanbaatar has at least 27 brick kilns and all use U-bearing coals as fuel. The kilns are diverse including Bull trench kilns (BTK), fixed trench kilns (FCK) and a range of Chinese kilns. BTK kilns have mobile metal stacks preventing insertion of dust collectors thus forcing fine U- bearing ash into discharge to the atmosphere. FCK kilns have fixed taller stacks fitted with ash collectors so less ash is vented. Some Chinese kilns vent fine ash. The fate of coarse ash (clinker) and recovered fine ash is unclear. Some of the ash appears to be added to unfired bricks, so radon hotspots are anticipated to be present in brick buildings. Of concern is the Nalaikh cluster (47°50'N 107°18'E) of 15 brick kilns that burn U-bearing coal and often fire inter-seam clays and therefore U-bearing bricks are likely.

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4.4 Uranium extraction from coal ash

Extraction of uranium from coal ash waste at CHP #4 has been achieved by Maslov et al. (2010a,b) using five chemical treatments: water, sodium carbonate, sulphuric acid, nitric acid plus hydrogen peroxide, and nitric acid plus hydrofluoric acid (Table8). Table 8 results of leaching U from coal ash waste (Maslov et al. (2010a, b). solvent treatment chemical Rank treatment chemical temperature duration yield 1 8M HNO3 + HF (10%) mixture 20C 24 hours >99.0% 2 8M НNO3 + H2O2 (10%) mixture 90C 2 hours 53.5% 3 H2SO4 90C 2 hours 45.4% 4 Na2CO3 90C 2 hours 9.2% 5 H2O 20C 24 hours 1.1%

Leaching with an 8M HNO3 + 10% HF mixture was remarkably successful. Extraction of uranium from solution and its purification was via an anion exchanger. After leaching no detectable238U or232Th or their decay products remained in the ash. Although only bench-scale, the test opens an avenue of research in Mongolia to extract uranium and other valuable metals from U-bearing coal ash to leave a clean ash suitable for all constructional and agricultural uses, and cut heavy metal contamination of groundwater and surface waters. In China, Sparton Resources (SRI: TSX-Venture) conducted large-scale tests on extracting uranium from a slurry of coal ash waste, sulphuric acid and hydrochloric acid (The Economist, 2010). For some types of ash, nitric acid was also used. The uranium content of the ash averaged 65 g/tonne and recovery was approximately the same as for in-situ leaching of conventional uranium deposits. According to The Economist (2010), Sparton Resources claimed it can “extract a kilogram of uranium for $77 or less”. This suggests that Mongolian coal ash may be economic sources of uranium, notably the Adunchuluun Mine whose ash contains 300 g/tonne of uranium plus germanium and rare earths (Luvsanvandan, 2012 manuscript). Sparton extract the uranium from the leachate via a coconut charcoal filter and an ion-exchange resin, using ammonium carbonate solution to precipitate yellow cake (a mixture of uranium oxides). 4.5 Uranium in construction materials

Construction materials are a health concern in Ulaanbaatar due to U-bearing ash waste being a key ingredient. Tests on these materials for uranium content are warranted, particularly for high-rise apartments built largely of cement, cement blocks and concrete. Brodhead (2008) found concrete to often be the cause of indoor radon in USA high-rise condominiums. Gerbish et al. (2000a, 200b, 2001) investigated the 238U, 232Th and 40K activities of construction materials in Ulaanbaatar and Darkhan, and gave results for materials produced in Darkhan (Table 9). Table 9 Dose rate using dosimeters on the surface of building materials produced in Darkhan. Data from Gerbish, Ganchimeg, Bayarmaa et al. (2001).

Rank material mean activity/concentration Bq/kg Radium-equivalent 238U 232Th 40K activity CRa.eq 1 Granite 120-350 200-250 340 702.0 2 Aggregate 66.0 81 660 232.6 3 concrete products 44.6 54 395 152.2 4 roof tile 40.0 56 430 153.2 5 concrete block 38.0 64 412 161.2 6 Soil 24-40 42-56 210 123.2 7 Cement 15-22 40 391 105.8 8 Sand 18-20 20 400 78.4 The ‘granite’ has elevated uranium activity. Low uranium activity for concrete blocks and concrete products suggests U-bearing ash was not an additive to these products in Darkhan. 16

4.6 Uranium in soil

Uranium occurs in the soils of dried-out soda lakes and associated playas; and in soils derived from granites, volcanic rocks, ash, coals, sandstones and hotspots of U-enriched phosphates. Monitoring of 238U (226Ra), 232Th, 137Cs, and 40K radionuclides in soils of the main centres of population is undertaken by the Nuclear Research Centre of the National University of Mongolia. The radionuclide contents of 1-2 kg samples are measured by low-background gamma spectrometry based on high-purity Ge detector of about 15% efficiency and 1.85 keV resolution for the1332.5 keV 60Co line. Measuring time is usually 4,000 seconds or more. Results released by Shagjjamba and Zuzaan (2006) are presented in Table 10. Table 10 Activity concentration of uranium, thorium and potassium in soil samples. (Data from Shagjjamba and Zuzaan, 2006) natural radioactive nuclides in soil – Bq/kg

238U 232Th 40K 49.0 ± 5.4 42.2 ± 5.6 1,181.0 ± 82.0 Darkhan 45.1 ± 4.4 32.7 ± 4.3 736.0 ± 53.1 Baruun-Urt 41.4 ± 4.3 50.7 ± 5.6 725.9 ± 52.0 Sukhbaatar 38.6 ± 4.2 36.3 ± 4.9 850.6 ± 57.8 Erdenet 36.6 ± 4.0 30.7 ± 5.0 677.8 ± 54.0 Muren 35.6 ± 3.8 27.3 ± 3.5 897.9 ± 57.0 35.0 ± 4.5 39.0 ± 4.9 826.0 ± 67.7 Ulaanbaatar 33.2 ± 9.4 39.0 ± 7.3 881.9 ± 94.3 29.0 ± 4.1 28.0 ± 3.1 778.0 ± 60.7 Mongolia mean 28.2 31.8 840.7 Undurkhaan 25.4 ± 3.1 28.5 ± 3.7 1,031 ± 60.8 World mean 25 25 370 23.8 ± 2.9 21.5 ± 3.1 939.0 ± 56.3 23.4 ± 3.7 38.1 ± 5.6 1,330.0 ± 88.3 22.5 ± 3.0 36.4 ± 4.5 780.4 ± 57.3 21.2 ± 3.5 26.3 ± 4.3 895.4 ± 104.3 20.0 ± 2.9 54.6 ± 5.5 741.5 ± 54.2 Bayanhongor 19.3 ± 2.5 22.2 ± 3.0 781.5 ± 48.1 Altai 18.1 ± 2.4 11.3 ± 2.2 322.4 ± 27.3 Choibalsan 15.5 ± 2.4 13.9 ± 2.6 965.7 ± 60.5 Ulgii 14.2 ± 1.9 25.8 ± 3.3 530.1 ± 36.6 The most striking result is the high activity of238U in Tsetserleg, Darkhan and Baruun Uurt, attributed by Shagjjamba and Zuzaan (2006) to thin soils being derived from U-bearing granites. Indoor radon tests are necessary on buildings made from aggregates of U-bearing granites with cement containing U-bearing ash. 17

4.7 Uranium in soda lakes 4.7.1 Recent discoveries Unconventional uranium resources exist in tracts of tens of thousands of soda lakes across Asia, notably Siberia, Chita, North-East China, Inner Mongolia, Mongolia, Western China, Tibet, Kazakhstan and southern Russia. Mongolia has about 3,500 lakes larger than 0.1 km2, of which more than 2,800 have salinities greater than 1 gram/litre (Egorov, 1993). While the vast majority of saline lakes are very small and only twelve exceed 50 km2, ten exceed 100 km2and two exceed 1,000 km2. Most saline lakes are in the Gobi and steppe zones, but some occur in the forest-steppe transition zone. Egorov (1993) estimated Mongolia’s total volume of saline water approaches 30km3. About 2,200 of these saline lakes are soda lakes, in which carbonate/bicarbonate ion concentrations exceed chloride ion concentrations. Although the chemistry of several hundred lakes has been investigated, uranium contents were not determined until recently. The first report containing uranium data was by Markwitz et al. (2008) for a dry soda lake in central Mongolia, followed by Linhoff et al. (2011) for soda lakes in eastern Mongolia and Isupov et al. (2011a) for soda lakes in north-west Mongolia. Although most soda lakes sampled are in known prospective uranium districts, it is remarkable that all contain significant levels of uranium. (Table 11). Table 11 Unconventional uranium deposits and occurrences in Mongolian Soda Lakes. Data from Linhoff et al. (2011), Markwitz et al. (2008) and Isupov et al. (2011).

Reference UNCONVENTIONAL URANIUM DEPOSITS AND OCCURENCES Map Soda Lakes province name latitude longitude major U status source

commodity concentration Uraniferous Soda Lakes SB-L Shar Burdiin Lake 48°19'6.96"N 114°31'18.66"E U 14,877 μg/L M50 DORNOD Linhoff et al. (2011) GY2-L Gurvany-2 Lake 48°19'42.24"N 114°30'44.22"E U 10,164 μg/L M46 - - NW Mongolia - - U 1,000 μg/L Isupov et al. (2011a) SB-L Gurvany-1 Lake 48°11'8.34"N 114°25'40.02"E U 271 μg/L occurrence GY2-L Tsaidam-2 Lake 48° 7'3.18"N 114°24'7.14"E U 140 μg/L M50 DORNOD Linhoff et al. (2011) SB-L Tsaidam-1 Lake 48°27'31.86"N 114°49'42.18"E U 57 μg/L GY2-L Gurvany-1 Stream 48°11'38.22"N 114°25'30.54"E U 50 μg/L World Health Organisation guidelines for drinking water U 15 μg/L WHO (2011a)

Uraniferous Dry Soda Lakes Markwitz et al. (2008) mg/kg occurrence L48 UL-3 TOV Jirmin Tsagaan Lake 47°55'52.20"N 106° 5'21.00"E U 350 determined by PIXE Canadian Soil Quality Guidelines – industrial U 300 mg/kg CCME (2007) UL-3 47°55'52.20"N 106° 5'21.00"E U 176 mg/kg Markwitz et al. (2008) L48 TOV Jirmin Tsagaan Lake occurrence UL-2 47°55'51.78"N 106° 5'19.32"E U 70 mg/kg determined by PIXE Canadian Soil Quality Guidelines – commercial U 33 mg/kg CCME (2007) Canadian Soil Quality Guidelines – residential and agricultural U 23 mg/kg CCME (2007)

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4.7.2 U content of soda lakes of Dornod Aimag The geochemistry and extremophile communities of the Dornod uraniferous soda lakes are described by Linhoff et al. (2011) and Sorokin et al. (2004). The Dornod soda lakes have possibly the highest natural uranium levels of any water body on Earth (Linhoff et al., 2011). Uranium concentrations in Shar Burdiin Lake (14,877 μg/L) is nearly 1,000 times higher than WHO guidelines for drinking water (15 μg/L). Dornod uraniferous soda lakes are candidates for commercial recovery by methods such as those described by Rapantova et al. (2007) for mine- water in the Czech Republic. Landsat TM imagery shows that the Dornod soda lakes freeze over in winter, due to extreme cold (-40C) and wind chill in the open steppe landscape. Being shallow, the soda lakes freeze solid as confirmed by the local population (Linhoff et al., 2011), and are close to the southern limit of discontinuous permafrost. In winter the carbonate salts at the surface are harvested as a laundry cleaning aid (Linhoff et al., 2011). This raises concern about exposure of local herders to high uranium content in their laundry as well as to uraniferous drinking water from nearby wells. Elevated uranium levels may be common among the 1,500 soda lakes enumerated by Egorov (1993) in Dornod Aimag, and some may prove economic for low-cost uranium mining. This view is supported by the multitude of uranium sources in Dornod including volcanic-hosted uranium deposits (e.g. Mardai), sandstone-hosted uranium occurrences and uraniferous coals (e.g. Aduunchuluun). A systematic study of the commercial potential of Dornod soda lakes and contiguous parts of Russia is underway for uranium, lithium and rare earth elements (Sklyarova et al., 2012). 4.7.3 U content of soda lakes of Central Mongolia The soda lakes of Central Mongolia are little known, even though the capital is in their midst. Only one uraniferous soda lake has been reported. Markwitz et al. (2008) detected a uranium concentration of 350 mg/kg by particle induced X-ray emission (PIXE) measurement on a sediment sample from the dry bed of Jirmin Tsagaan Lake in Soum. The lake is in rolling steppe in discontinuous permafrost. Gamma spectrometry confirmed uranium but revealed238U decay products were at a level corresponding to only about 3 mg/kg uranium for a system in radioactive equilibrium. Markwitz et al. (2008) point out such a high degree of separation at high concentration would be unique, if confirmed. However, this disequilibrium of the uranium decay series (the paucity of decay products) may be explained by recent precipitation of uranium during drying out of the lake margins. The uranium content of dry sediment of Jirmin Tsagaan Lake (350mg/kilo) is more than 15 times greater than Canadian soil quality guidelines for residential and agricultural land use (CCME, 2007). It is unclear if this is an isolated uranium-rich hotspot or if it is of wider relevance to arable farming and traditional pastoral livelihoods in Argalant Soum.

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4.7.4 U content of soda lakes of Western Mongolia A Russian team recently published a baseline study of uranium and lithium of closed lakes in Western Mongolia, with uranium levels reaching as high as 1 mg/L. Hyargas Nuur contains an estimated 6,000 tonnes of uranium (Isupov et al., 2011a) in 75.2 km3 of water in an area of 1,480 km2. Uranium is concentrated in soda lakes, whereas lithium is concentrated in chloride lakes (Shvartsev et al., 2012). High maximum levels of lithium (50 mg/L), boron (100 mg/L) and bromide (460 mg/L) were reported by Isupov et al. (2011b). 4.7.5 Geochemical model for soda lakes Soda lakes are a distinctive worldwide class of salt lakes typified by very high carbonate/bicarbonate alkalinity of pH 9 to 11, and moderate to very high salinity. Major ions + - 2- - 2- 2+ 2+ are Na , CO3 , HCO3 , Cl and SO4 . In contrast Ca is virtually absent, and Mg scarce. The scarcity of calcium ions permits phosphate ions to be abundant, contributing to high primary productivity (Foti, 2007). The twin extremes of high pH and high salinity render soda lakes a unique ecosystem. Soda lakes have sodium carbonate/bicarbonate as the major salt in solution, with different physical and chemical properties than sodium chloride, notably being a much weaker electrolyte. The distinctive chemistry of soda lakes ensures a high buffering capacity that maintains stable the high pH (Foti, 2007). Soda lakes are in the deserts, arid steppe, and forest-steppe of Mongolia, associated with soda/saline playa flats in regions with calcium/magnesium caliche soils. In general the climate is sharply continental, with hot summers and very cold winters.

The origin of soda lakes is unclear. One theory suggests Na2CO3 is contributed by volcanism; another attributes the high pH to sulphate reduction in anaerobic basins (Grant, 1992). Others suggest the alkalinity is due to climatic and geological conditions such as low concentrations of 2+ 2+ - Mg and Ca and high CO2/HCO3 levels in ground waters (Foti, 2007). Such theories have merit and help explain the geochemistry, but none are particularly robust. A general model is proposed here based on fieldwork in Mongolia. Crusts of calcite/dolomite on clasts in gravels occur only on the undersides of clasts, never on the upper sides unless inverted by burrowing mammals or mining. The crusts serve as helpful geopetal indicators when assessing more than 150 placer gold deposits by discriminating between in situ gravels and technogenic gravels, such as bulldozed overburden (Fig. 4).

Figure4 Typical carbonate geopetal crust on the underside of a magnetite nugget, Shariin Gol goldfield, Mongolia. 20

The carbonate crusts are attributed to evaporation of thin films of water pulled upwards by capillary action. Wide diurnal temperature fluctuations ensure the last water to evaporate is always on the underside of clasts. Here a carbonate geopetal forms, grows and survives. A conservative estimate is half a million square kilometres has carbonate crusts averaging 3mm thick, suggesting at least1.5 km3 of precipitated carbonates. Precipitation is assumed to removeCa2+ and Mg2+ ions at a rate sufficient to leave sodium carbonate/bicarbonate as the major salt in solution. When groundwater is strongly depleted in calcium and has less than half as muchCa2+as bicarbonate then calcium carbonate precipitates preferentially from solution whenever evaporation occurs. A geochemical divide is crossed and a soda lake inevitable, as pointed by Hardie and Eugster (1970). The geochemical divide is reinforced not only by evaporation but also by two more processes: freezing and sublimation. Field observations suggest that all Mongolian soda lakes freeze over in winter, and as reported by Linhoff et al. (2011) shallow soda lakes freeze solid. Fractionation by freezing is expected to leave pockets of supersaturated brine from which precipitation of CaCO3 is inevitable. Uranium salts may also crystallise, accounting for the very high uranium content of the dry bed of a soda lake reported by Markwitz et al. (2008) in Central Mongolia. Normal freezing over of a soda lake creates an ice cover averaging one metre thick. The ice insulates the trapped water preventing more freezing. But soils also freeze and the trapped water becomes tightly sealed. A modest increase in hydrostatic pressure is sufficient to heave the ice cover up into an ‘ice mound’ prone to split, releasing a sheet of cold water over the surface of the very cold ice. Flow stops when viscosity increases and the leading edge of super- cooled water entangles in a slush of obstructive ice crystals. Freezing reseals the splits causing hydrostatic pressure to increase and the ice cover bursts again. This repetitive process stacks thin layers to produce a super-thick ice shield known as khalia toshin (Mongolian), taryn (Yakutian), aufeis (German) and naled (Russian). Every winter in Mongolia several thousand ice shields grow 2 to 5 metres thick, and exceptionally 10 metres thick (Grayson, 2010). By late winter, ice shields dominate most springs and flowing streams. Ice shields are less evident over soda lakes, perhaps due to less hydrostatic pressure, but when they occur residual brines are expected to supersaturate and trigger large-scale precipitation of CaCO3. Freezing over, ice shield growth, sublimation, frost growth and snow falls interact and result in complex waxing and waning of lake ice cover and ice shields throughout the winter. Sublimation of ice directly to vapour is the prime cause of ice loss in winter, particularly from soda lakes on arid lowlands. Sublimation occurs on still dry days, sometimes alternating with localised melting and normal evaporation. Sublimed vapour often condenses into visible vapour (‘mist’) that nucleates on ice shields to form ice crystals including frost flowers (Fig. 5). 21

Figure 5 A naled ice shield in the Uliastai valley in Ulaanbaatar, December 2010. A fresh layer of water on top of old ice (dark) has halted due to a slush dam and frozen solid on top (white). In the last few hours a sprinkling of frost flowers has grown on top of all ice surfaces.

2+ - 2- Removal of water by freezing results in supersaturation of Ca , HCO3 and CO3 , and consequent removal of calcium ions by precipitation of CaCO3. The fate of uranium ions is not clear. Uranium ions are conservative during freezing of seawater and become locked in sea ice which is salt-depleted because sea salt is mostly excluded. Uranium ions are re-released to the seawater once the sea ice melts. A similar conservative process may prevail in uraniferous soda lakes. Abundant frost flowers on the ice surface (Fig. 5) create an aerial escape route for ions. Frost flowers serve as wicks pulling saline water upwards by capillarity from brine films on the ice surface. The frost flowers are delicate and vulnerable to destruction not only by sublimation but by becoming shattered and airborne in wind. This aerial escape route is used by minor constituents such as lithium, bromide and boron from sea ice and presumably also from soda lakes. It raises the possibility that uranium may be released from frozen soda lakes to the atmosphere as sublimed vapour and airborne ice particles. 22

Large dust carpets are visible on Landsat TM and Google Earth downwind of many soda lakes indicating large volumes of uraniferous materials are wind-blown from exposed lake margins, dried out lake floors and ice covers. The existence and persistence of thousands of small soda lakes is problematic but best attributed to wind deflation creating broad shallow blow-outs down to the water table or permafrost. Groundwater floods the depressions, resulting in soda lakes. Drying out by evaporation, sublimation of ice and oscillating water tables creates opportunities for wind deflation to maintain the basins. U-bearing soils may be extensive downwind resulting in larger uranium resources, and increasing the risk to human health among local people. 4.7.6 Geochemical health issues of soda lakes – Arsenic and selenium Arsenic has a bipolar distribution in Mongolian groundwaters, approximating to the distribution of not only arsenopyrite- associated gold but also the extent of Mesozoic coal basins (Tumenbayar et al. 2010). Elevated levels of arsenic are reported in Mesozoic coals burnt in Ulaanbaatar, particularly coals from Nalaikh (121 ppm As) and Baganuur (183 ppm As) (WHO, 1995). These levels are higher than in 97-99% of >7,000 analyses of USA coals (Kolker et al. 2005) and imply several thousand tonnes of arsenic contaminate the capital city in ash waste. While leaching of arsenic from coals is facilitated by weathering, oxidation and hydrolysis, once released then sodic groundwater and soda lakes may play an important role. This is suggested by the highest arsenic levels being reported from wells in regions with soda lakes and sodic soils over coal basins. The WHO guidelines for arsenic in drinking water (0.01 mg/L) are exceeded in wells in Govi-Sumber (x 3), Dornogovi (x 2.4) Dornod and Govi-Altai (x 1.8) and Sukhbaatar (x 1.7), with the peak values reported for Khatanbulag soum in Dornogovi (x 7.5). These districts are characterised by Mesozoic coal basins, sodic soils and soda lakes. The National Arsenic Survey (WHO, 2005) confirmed arsenic poisoning being endemic in areas with elevated As levels in well water, with symptoms displayed by 82.4% of the people surveyed. It is evident that the arsenic poisoning affects several thousand people in the Gobi regions. Tukh Lake in the Darhad valley of Huvsgol Aimag has the highest known arsenic levels for a Mongolian soda lake. Arsenic levels of 0.5 to 2.4 mg/L, 50 to 240 times the WHO drinking water guidelines, were revealed in analyses by Hamamura et al. (2012) of 1:1 evaporate:water extracts, together with selenium levels of 2 mg/L that are 50 times above the WHO guidelines. Herders visit Tukh Lake to harvest the “hujir” (salt evaporates) to make tea, consumed daily. Barber et al. (2009) investigated the chemical constituents of hujir consumed by families near Tukh Lake and found soluble arsenic concentrations ranging from <0.05 to 1.0 mg/L. In the area, Hamamura et al. (2012) discovered arsenite is produced by alkaliphile bacteria in arsenate- reducing anoxic cultures; and discovered elemental selenium is produced by selenate-reducing cultures. Alkali extremophile bacteria associated with Mongolian soda lakes are therefore significant geochemical players for arsenic and selenium mobility.

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4.7.7 Geochemical health issues of soda lakes – Fluoride The association of soda lake regions and endemic fluorosis is recognised by the World Health Organisation (Edmunds and Smedley, 2005; WHO, 2006). Mongolia is the world’s third largest fluorspar producer and has large fluorspar resources in widespread districts including 58 Soviet deposits and 288 occurrences (Dejidmaa et al., 2001, Grayson and Baatar, 2009). Fluorspar and uranium districts overlap, and often include soda lakes and highly alkaline groundwater. Examination of 110 hydrothermal fluorspar-quartz veins in Tov, Dundgovi, Donogovi and Khentii aimags revealed fluorspar grades dropped to sub-economic levels in the uppermost 1 to 3 metres and often show signs of leaching. This implies systematic regional leaching of fluorite (CaF2) from soils across thousands of square kilometres, in spite of fluorite -11 having a low solubility product (kSP) at 20°C of 3.9 x 10 . This low solubility implies extensive leaching of fluorite to fluoride ions is impossible in waters high in Ca2+ (Hurtado et al., 2000). We propose bulk removal of Ca2+ as carbonate crusts as the single geochemical factor that triggers regional leaching of fluorspar veins in Mongolia. Where fluorspar is rare, dental caries are expected due to lack of sufficient fluoride in the drinking water, as in the extreme case of Ulaanbaatar (Table 12). Conversely, where fluorspar is abundant, dental fluorosis is expected to be endemic due to excessive fluoride in the drinking water (Table 12).

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Table 12 Fluoride levels in groundwater in Mongolia and elsewhere in the world, compared with WHO guidelines and Mongolian standards. fluoride Country Details micrograms per source % children with dental fluorosis litre Lake Nakuru 2,800 mg/L KENYA Lake Elmentaita 1,640 mg/L WHO (2006) TANZANIA Momella soda lakes 690 mg/L MONGOLIA Tsenker Hot Spring 25 mg/L Gendenjamts(2005 WHO Guidelines – risk of crippling skeletal fluorosis WORLDWIDE if fluoride in drinking-water above this level 10 mg/L WHO (2006) Sukhbaatar Soum, Sukhbaatar Aimag 2.0-3.5 mg/L Dorj (2007) Sukhbaatar Aimag 1.63-2.17 mg/L Zolboo et al. (2001) Ulaan-Uul railway station – 50% 2.05 mg/L MONGOLIA Sainshand railway station – 40% 1.97 mg/L Bayarmaa, Norjmaa and Zuunbayan railway station – 75% 1.96 mg/L Bolormaa (2006) Àirag railway station – 36.3% 1.95 mg/L Dornogobi Aimag 1.41-1.94 mg/L Zolboo et al. (2001) WHO Guidelines – risk of dental fluorosis WORLDWIDE if fluoride in drinking-water above this level 1.5 mg/L WHO (2006) MNS drinking water standards – HIGHEST permitted 1.5 mg/L MNS 3900:1986 Ar Janchivlan bottled water 1.1 mg/L Dornod Aimag 1.1 mg/L Zolboo et al. (2001) MONGOLIA Khirjirt bottled water 1.0 mg/L Terelj bottled water 0.8-1.0 mg/L MNS drinking water standards – LOWEST permitted 0.7 mg/L MNS 3900:1986 South Gobi Aimag 0.57-0.91 mg/L Gobisumber Aimag 0.52 mg/L Gobi-Altai Aimag 0.26 mg/L MONGOLIA Arkhangai Aimag 0.24 mg/L Zolboo et al. (2001) Bayan Olgii Aimag 0.16 mg/L Bulgan Aimag 0.14 mg/L Ulaanbaatar 0.06 mg/L Dental fluorosis is endemic in Mongolia’s fluorspar districts. Bayarmaa, Norjmaa and Bolormaa (2006) found dental fluorosis in 50% of a sample population of 1,012 children aged 3-7 years in Airag, Sainshand, Zuunbayan and Ulaan Uul, with 75% affected in some villages. Dorj (2007) reported efforts to combat endemic dental fluorosis in the centre of Sukhbaatar Aimag.

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4.8 Uranium in extremophile ecosystems 4.8.1 U and extremophile microorganisms Soda lakes are remarkable ecosystems. They are, “the most productive aquatic lakes in the world, with productivity rates an order of magnitude greater than the mean rate of all aquatic environments on Earth." – Grant (2006). Soda lakes are highly alkaline saline environments too extreme for higher life-forms. This means a scarcity of herbivores, allowing alkaliphilic extremophile organisms to thrive. Soda lakes are near-supersaturation with CO2 (bicarbonate ions) and this removes the CO2 limitation on plant growth. Thirdly, soda lakes have a wide range of micronutrients, removing most chemical limitations on growth. Finally, extremophile organisms can exploit these favourable conditions to the full, by multiplying rapidly, spreading easily and rapidly responsive to seasonal and diurnal variations in temperature, salinity and water level. Soda lake extremophile organisms are diverse and interact in elaborate ecosystems. The main drivers are blue-green bacteria (Cyanobacteria)that produce fixed carbon which is then used by a vast range of aerobic and anaerobic chemo-autotrophs, notably halomonads, bacilli and clostridia methanogens (Grant, 2006). Other extremophiles drive nitrogen and sulphur cycles. Some alkali extremophiles can bioaccumulate uranium (e.g. Spirulina) making them candidates for bioremediation of uranium-contaminated sites by leaching uranium (VI) as uranyl ions, and for recovering uranium from low-grade ores (Cecal et al., 2004). This suggests uranium in soda lakes and associated sediments may be being redistributed and concentrated by bioaccumulationin certain extremophile organisms. Uraniferous soda lakes of north-east Mongolia are a research focus of Russian-led microbiologists (Sorokin et al., 2004) who may gain the knowledge-base to attempt commercial uranium extraction by exploiting extremophile organisms’ rapid kinetics of U (VI) reduction leading to uraninite precipitation due to the low solubility of uranium (IV) oxide (UO2). Yi et al. (2006) used mixed cultures of sulphate-reducing extremophile bacteria to achieve a uraninite yield of 99.4%, mostly within 48 hours, and discovered that if nitrates are present then uraninite re-dissolves. This suggests high nitrates from livestock rearing near soda lakes may mobilise uranium as U (VI) in solution which might be problematic for shallow wells. Inner Mongolia has factory-based production of Spirulina foodstuffs (Habib et al., 2008). Some factories switched from industrial CO2 to CO2-rich waters from nearby soda lakes. Vigilance is required to ensure such waters have very low levels of uranium, arsenic, selenium and other elements to prevent bioaccumulation to toxic levels.

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4.8.2 U and extremophile higher plants Mongolian soda lakes often have submerged, emergent and marginal extremophile higher plants, and soda soils colonised by extremophile forbs, shrubs and trees. The remarkable Toghraq tree (Populus euphratica Olivier =Populus diversifolia Schrenk) occurs in Mongolia, China and elsewhere. It is the largest alkali extremophile organism and its roots absorb sodium carbonate/bicarbonate salts and essential water from alkaline soils (Ottow et al., 2005).Sap is harvested by herders as baking soda for cooking, soap and medicine. If uranium is conservative, then bioaccumulation of U (VI) may be significant. In China, Yabuki et al. (1997) report trona (NaHCO3·Na2CO3.2H2O) is the dominant carbonate/bicarbonate salt, forming well-developed euhedral crystals that suggest trona crystallized first. Baylissite (K2CO3·MgCO3.4H2O) occurs as colourless fine-grained aggregates, usually adjacent to trona and sometimes enclosed by sylvite (KCl). Other minerals include K carbonates, Na,Ca carbonates and Ca,Mg carbonates. 4.8.3 U and extremophile higher animals Mongolian soda lakes may support extremophile invertebrates, amphibians, fish and birds. The biomass of crustaceans may be considerable, notably of the brine shrimp (Artemia) and a further 25 species of branchiopods (Alonso, 2010). Many are living fossils from Cretaceous and pre-Cretaceous times and merit conservation measures (Naganawaet al., 2001). Artemia undergoes population explosions in Mongolian soda lakes and is an ideal laboratory animal that bioaccumulates uranium and other heavy metals. Artemia has methallothionein proteins (MTLP) built of 48 amino acids – fewer than the 60-68 usual in the Animal Kingdom. MTLP from Artemia has a potential for sequestering heavy metals in mining and remediation (Acey, 2007). This suggests Artemia and other branchiopods may have sequestered uranium in Mongolian soda lakes assisted by MTLP. However some research suggests MTLP might not sequester uranium (Massarin et al., 2010). Uranium radiotoxicity is negligible for crustaceans such as Daphnia magna (Massarin et al., 2010) due to the low penetrating power of alpha particles attenuated by water; and due to very low internal exposure levels. In contrast, Sarapultseva and Bychkovskaya (2010) suggest at a dose as low as 0.1 Gy, a thousand times lower than predicted as lethal (100 Gy), the probability of death of Daphnia magma increases. Uranium chemotoxicity is acute for Daphnia magna (Zeman et al., 2008, Massarin et al., 2010) at uranium concentrations of 75 μg/L in water. Even at concentrations as low as 10 μg/L, there is loss in carbon assimilation and fecundity.

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4.9 Uranium in groundwaters 4.9.1 U in bottled water of Ulaanbaatar Casual inspection of 25 brands of bottled water on sale in Ulaanbaatar revealed 0.5 L bottles of Ar Janchivlan water labels claiming “Uran 1.8 mg/L” (Fig. 6). The U, Ra, F and Se levels are high compared with WHO guidelines for drinking water. Ar Janchivlan (=North Janchivlan) is a spa in Erdene soum (47°36'N 107°37'E) in Tov Aimag, 8km south-east of the Ulaanbaatar boundary but 55 km from the edge of the Ulaanbaatar conurbation (UB).

Figure 6 Ar Janchivlan bottled water on sale in Ulaanbaatar, October 2nd 2012. This is a gassy Na/Ca/Mg bicarbonate soda water. According to the label, uranium (“Uran”) is 0.05 mg/L, radium (“Radi”) is 10-18.5 mg/L, fluoride (“Ftorid”) is 1.5 mg/L and selenium (“Selen”) is 0.05 mg/L. 28

If the label is correct, this water has almost twice the U content of the maximum reported by Irwin (1997) for 55,000 groundwater samples in the USA (Table 13). Table 13 Uranium levels in groundwater in Mongolia and elsewhere in the world, compared with guideline limits of the World Health Organisation (WHO) and national agencies. Country details Micrograms source per litre MONGOLIA Ulaanbaatar: labels on Ar Janchivlan bottled water 1,800 μg/L this paper USA maximum in 55,000 groundwater samples 946 μg/L Irwin (1997) MONGOLIA Dornod : TS-1-1 well near Tsaidam-1 soda lake 102 μg/L Linhoff et al. (2011) MONGOLIA Dornod : SB-1 Shar Burdiin Well 86 μg/L MONGOLIA Ulaanbaatar: maximum in 129 wells in 7 Districts 57.2.μg/L Nriagu et al. (2012) USA maximum contaminant level for naturally occurring uranium 30 μg/L EPA rule WORLDWIDE Recommended revised WHO guideline for U in drinking water 30 μg/L Hirose & Fawell (2012) USA 979 water supplies ≥20 μg/L MONGOLIA Ulaanbaatar: average 4 wells in Bayangol District 18.6 μg/L Nriagu et al. (2012) WORLDWIDE WHO guideline limit for U in drinking water 15 μg/L WHO (2011a) USA 2,228 water supplies ≥14 μg/L MONGOLIA Dornod: TS2-1 well near Tsaidam-2 soda lake 12 μg/L Linhoff et al. (2011) MONGOLIA Ulaanbaatar: average 4 wells in Bagakhangai 11.3 μg/L GERMANY maximum permitted for natural mineral waters 10 μg/L Nriagu et al. (2012) GERMANY maximum permitted for spring waters 10 μg/L GERMANY maximum permitted for table waters 10 μg/L MONGOLIA Dornod: BW Background Well 7 μg/L Linhoff et al. (2011) MONGOLIA Ulaanbaatar: average 7 Districts 7 μg/L Nriagu et al. (2012) MONGOLIA Ulaanbaatar: average 11 wells in District 6.7 μg/L MONGOLIA Dornod: TS2-2 well near Tsaidam-2 soda lake 5.0 μg/L Linhoff et al. (2011) USA average in 55,000 groundwater samples 4.8.μg/L Irwin (1997) MONGOLIA Ulaanbaatar: average 55 wells in Soningo District 4.6 μg/L MONGOLIA Ulaanbaatar: average 129 wells in 7 Districts 4.6 μg/L Nriagu et al. (2012) MONGOLIA Ulaanbaatar: average 19 wells in Bayanzurkh District 3.7 μg/L USA average in over 28,000 domestic water samples 2.5 μg/L MONGOLIA Ulaanbaatar: average 27 wells in UB Sukhbaatar District 2.4 μg/L Nriagu et al. (2012) EUROPE average in 5,474 tap water samples 2.2 μg/L GERMANY guideline for waters used in preparing infant food 2.0 μg/L MONGOLIA Ulaanbaatar: average 9 wells in District 1.6 μg/L Nriagu et al. (2012) MONGOLIA Ulaanbaatar: minimum detected in 129 wells in 7 Districts <0.01μg/L Ar Janchivlan spa is one of several spas associated with the Janchivlan mineral complex dominated by a 500-600km2 uraniferous granitic pluton emplaced in late Triassic to early Jurassic times. Soviet drilling reported uranium grades of 0.002% to 0.28% at Janchivlan (U308, 2007).The main host rocks are coarse-grained biotitic granites substantially transformed by argillic, chloritic and phyllic alteration plus silicification, permissive to mineralization by near- surface secondary uranium mineralisation including uraninite and torbernite. At depth, the primary ore of fluorite-sulphide-uraninite plus coffinite was proved by Soviet drilling and later confirmed by the junior company Uranium 308 (OTCPK:URCO, URCO-OTCBB). 29

4.9.2 Uranium in groundwater of Ulaanbaatar Ulaanbaatar is totally dependent on groundwater aquifers for water supply. Public water supply is from municipal wells tapping unconfined Quaternary gravel aquifers under the floodplain and terraces of the Tuul River on which the city stands. Some wells produce water from deeper partially-confined Neogene aquifers. Private supply is from a few permanent springs, numerous shallow wells, and some industrial wells for producing bottled water, soft drinks, vodka and food processing. The aquifer recharged from the Tuul River, its tributaries and their gravels, and to a lesser extent from surface runoff and fissure flow from surrounding mountains notably the granitic massif of Bogd Khan Uul. The UB aquifer is over-pumped, and the drop in the water table is a matter of public concern (Emerton et al., 2009) even though a grid of additional municipal wells has been constructed upriver. The level of the Tuul River is falling due to a combination of over-pumping the aquifer, decrease in snow cover and snowmelt, and decrease in summer flows. Increasing aridity is attributed to climate change with loss of tree cover and retreat of permafrost (MNET, 2010). Prior to 2009, little was known about uranium in the Ulaanbaatar groundwater. Then, Nriagu et al. (2012) analysed water from 129 wells in seven of the nine sub-divisions of Ulaanbaatar by inductively coupled plasma mass spectrometry (ICP–MS) in Clean Lab methods. They reported “surprisingly elevated” levels of uranium (mean, 4.6 μg/L; range <0.01–57 μg/L). Values for many samples exceeded the World Health Organization’s current guideline of 15 μg/L for uranium in drinking water (WHO, 2010). Nriagu et al. (2012) conclude that “The levels of uranium in Ulaanbaatar’s groundwater are in the range that has been associated with nephrotoxicity, high blood pressure, bone dysfunction and likely reproductive impairment in human populations. We consider the risk associated with drinking the groundwater with elevated levels of uranium in Ulaanbaatar to be a matter for some public health concern and conclude that the paucity of data on chronic effects of low level exposure is a risk factor for continuing the injury to many people in this city.” Reassessment is required. The Ulaanbaatar Administrative Area includes districts far from the Ulaanbaatar conurbation (UB). One of the seven districts tested is Bagakhangai (47°21'N 107°29'E) located 73 km south-south-east of UB across open countryside and with different geology, geomorphology and groundwater. The uranium content of the four Bagakhangai wells tested average 11.3 µg/L. This is a matter of serious concern, but only in Bagakhangai. Of interest, between Bagakhangai and UB is the Janchivlan mineral district (Tumenbayar et al., 2000) which includes uranium mineralisation (see Section 4.9.1 above), heavily mineralised spa waters and two bottled water factories, Janchivlan and Ar Janchivlan. The label of Ar Janchivlan bottled water proclaims a very high level of uranium (Fig. 6). Excluding Bagakhangai, the wells tested in the UB conurbation have an average level of uranium of 4.4 μg/L which is far below the WHO guidelines of 15µg/L.

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However, within UB, the Bayangol District is of most concern, with the four wells tested having high uranium levels averaging 18.6μg/L. These wells appear to be a hotspot and should be quarantined and shut down. A possible cause is leaching of uranium by water percolating through U-bearing ash waste dumps from combustion of U-bearing coal in CHP#2, 3 and 4. As it is worldwide, in Mongolia it is assumed that uranium is so tightly locked in coal ash that natural leaching of uranium ions from the ash dumps into the groundwater will not occur, however, this assumption is questionable. Maslov et al. (2010) reported leaching from Baganuur ash of 1.1% of uranium content over a period of 24 hours by water at 20C. This suggests contamination by uranium may pose a long term threat to the groundwater resources on which Ulaanbaatar is totally dependent for water supply. The threat of the scale and extent of power plants and ash settling lagoons in the capital city is illustrated in Figs. 7 and 8.

Figure 7 Unlined slurry lagoon receiving U-bearing ash from CHP plant #3 in Ulaanbaatar. The remaining 121 wells tested in UB have average U concentration of 3.9 µg/L, which is still a matter of concern, being significantly above the average U concentration of 2.2 µg/L for 5,474 tap water samples in Europe (EFSA, 2009), and 2.5 μg/L for 28,000 domestic water samples in the United States (USGS, 2006; ATSDR, 2011). Local rocks and soils were considered by Nriagu et al. (2012) to be the source of the uranium and they cite Markwitz et al. (2008): “detected uranium in sand and soil samples from Ulaanbaatar with the concentration reaching 350 μg/g in one sample from a dry lake bed”. However the lake-bed is not in Ulaanbaatar but at 47°55'51.78"N 106°5'19.32" in Argalant Soum in open countryside 30 km west of the Ulaanbaatar Administration boundary and 61 km west of UB city centre. The lake-bed is remote from the Tuul watershed and is not connected to the Ulaanbaatar aquifer.

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Figure 8 Three slurry lagoons settling uraniferous ash from Ulaanbaatar CHP Plant No. 4. Remarkable changes in appearance are visible in this time series of Google Earth images from 2005 to 2010. The large volume of ash sediment fills the lagoons putting them out of service until the ash has been excavated and removed to be either dumped elsewhere or sold as construction materials.

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4.10 Uranium in surface waters 4.10.1 U in flowing water Uranium occurs in trace amounts in rivers of north-central Mongolia (Ganbold et al., 2001). The Tuul river through Ulaanbaatar has a peak U concentration of 985 ppb at Sonsgolon bridge(47°52'27"N 106°47'3"E) downstream of CHP #2, 3 and 4 and the industrial zone of the city (Gerbish et al., 2001) (Table 14). The bridge is 10 km downstream of Zaisan where peak uranium levels in lichens are reported. Peak values may be due to proximity to the stack of CHP#2 which vents U-bearing ash from combustion of U-bearing coal. The stack plume sometimes collides with Bogd Khaan Uul and snowmelt and hillwash would contaminate the river. Table 14 Uranium in water of the Tuul river, flowing past Ulaanbaatar. Information from Gerbish et al. (2001).

Sampling point city U ppb Flow

Soldier's town 143 Tuul river flow river Tuul Ubulan, Tuul river 104 Gachuurt 328 Bayanzukh bridge 231 Ikh Tenger bridge 81 Zaisan City 338 Sonsgolon bridge Centre 985 upstream of effluent discharge 235 downstream of effluent discharge 86 Yarmag 61 biofactory 127 Songinokhairkhan 123 Cliff 92 Poultry Farm 76 Dalai and Ishiga (2012) report peak values of As, Pb, Zn, Cu, Ni, Cr, and V in the city section of the Tuul River, and their assessment using Sediment Quality Guidelines (SQG) shows levels of arsenic (6–23 ppm) and chromium (91.3 ppm) at levels likely to cause adverse aquatic biological effects.

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4.11 Uranium in stream sediments

Uranium minerals are found as accessory grains in placer deposits, particularly in cassiterite placers and columbite-tantalite placers associated with uraniferous tin granites, as exemplified by the Janchivlan mineral district (Tumenbayar et al., 2000). Analysis by instrumental neutron activation analysis using epithermal neutrons (ENAA) for a suite of 41 elements on sediment samples from rivers of central and northern Mongolia was done by Gerbish et al. (2008). Uranium was detected in all 14 sediment samples in trace amounts (maximum 12.4 ppm; Table 15). Table 15 Uranium in sediment of rivers in north-central Mongolia. Information from Gerbish et al. (2008). U mg/kg rank stream District Sampling point (ppm) 1 Selbe Ulaanbaatar city (central) Lion bridge 12.40 2 Tuul Ulaanbaatar city (south) Ulaanbaatar 10.50 3 Tuul Ulaanbaatar city (east) Gachuurt bridge 9.98 4 Dundgol Ulaanbaatar city Peace bridge 8.13 5 Shariin Gol Selenge Aimag bridge 7.71 6 Tuul Central Aimag bridge 7.41 7 Khangal Erdenet city Ulaantolgoi 5.63 8 Kharaa Gol Darkhan city Darkhan bridge 5.16 9 Tuul Central Aimag Ovoot bridge 5.01 10 Govil Erdenet city Erdenet town 4.82 11 Tuul Central Aimag Altan Dornod, Zaamar 4.60 12 Soil Erdenet city (central) central part 4.52 13 Uliastai Ulaanbaatar city (east) Uliastai bridge 4.19 14 Khangal Erdenet city (central) Erdenet bridge 3.64

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4.12 Uranium in vegetation 4.12.1 Uranium in lichens The ability of lichens and mosses to bioaccumulate heavy metals is well-known. Lichen biomonitoring was applied to air pollution in Ulaanbaatar by Gerbish et al. (2005) and Ganbold et al. (2005) using Cladonia stellaris and Parmelia separata. The lichens were subjected to Instrumental Neutron Activation Analysis (INAA) with epithermal neutrons to determine 35 elements. The average uranium content of lichens on Bogd Khaan Uul in Ulaanbaatar (3.45 ppm) is 15.9 times greater than for lichens in distant rural areas (Table 16). Table 16 Uranium content of lichens in Ulaanbaatar compared to distant rural areas. (adapted from WISE, 2011 and WNA, 2012). U content rank setting region location lat N/long E mg/kg 1 Ulaanbaatar Bogd Khan Uul Zaisan Am 4751’ 10653’ 3.45 2 Ulaanbaatar Bogd Khan Uul Bogini Am 4751’ 10656’ 0.68 3 rural Khentii Burkhan Khaldun Uul 4844’ 10902’ 0.25 4 rural Hovsgol Ulaan Uul 4551’ 9798’ 0.13 The uranium may originate from airborne fine U-bearing ash from combustion of U-bearing coals. Stack emissions from the three combined heat and power stations – CHP #2, 3, 4 – are important, but large emissions arise from drying of the U-bearing ash settling lagoons, plus major cumulative emissions from 175,000 domestic fires in the ger areas and 800coal-fired heating plants. This may account for the five-fold increase westwards in the uranium content of lichens in a distance of less than 5 km westwards from Bogini Am (0.68 mg/kg) to Zaisan Am (3.45 mg/kg),as the main stack of CHP#2 is only 4 km WNW of Zaisan. Uranium alone need not be the cause of air pollution damage to epiphytic lichens on Bogd Khaan Uul described by Hauck (2008), which may be more likely due to a combination of high sulphur, soot and toxic metals. The city centre is now a lichen desert, with the only epiphytic lichens being dead, stunted and infertile. 4.12.2 U in mosses Moss biomonitoring was applied to air pollution in Ulaanbaatar by Gerbish et al. (2005) and Ganbold et al. (2005) using Rhytidium rugosum, Thuidium abietinum and Entodonconcinnus on Bogd Khan Uul. Uranium levels are high on Bogd Khaan Uul but with no clear distinction between Bogini Am (2.34 and 4.29 mg/kg) and Zaisan Am (3.99 mg/kg). The median uranium value of 3.53 mg/kg is much higher than for mosses in Serbia (0.32mg/kg), Romania (0.28mg/kg Bosnia (0.21mg/kg), Bulgaria (0.20mg/kg), South Urals (0.19 mg/kg),), Poland (0.08mg/kg) or Norway (0.017mg/kg)(Ganbold et al., 2005). In world terms, the mosses of Bogd Khaan Uul have very high uranium median value (3.53 mg/kg) and maximum value (4.27 mg/kg) rivalling mosses near to uranium processing facilities in the South Urals of Russia (4.60 mg/kg) and uranium mines in Bulgaria (4.27 mg/kg) reported by Marinova et al. (2009).

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4.13 Uranium in air

Uranium is liable to become airborne as part of uraniferous dust particles. Pale dust blows from playa flats and dry beds of soda lakes. Remote sensing and ground truthing suggest that smaller soda lakes are deflation hollows where wind has removed topsoil down to the local water table or top of permafrost. After blow-out, return of a protective mantle of normal vegetation is unlikely due to the extreme alkalinity of the water and subsoil. Devoid of protection, the hollow remains vulnerable to further erosion by wind. Large volumes of U- bearing dust might be dispersed. Analyses for uranium in dust are needed, expanding the research of Davy et al. (2011) into elements in airborne dust in Ulaanbaatar, to enable benchmarking against the 0.15 to 0.40 ng/m3of uranium in air in 51 urban and rural areas across the USA (EFSA 2009). Coal dust blows from waste dumps, coal stockpiles, coal loading areas and coal trucks at many coal mines in Mongolia, including mines producing U-bearing coals such as Baganuur, Shivee Ovoo and the small mines at Nailakh. While some coal dust may remain airborne as part of the regional atmospheric flux, aprons of settled coal dust are visible by remote sensing for 10-15 kilometres downwind of some mining operations (Grayson and Baatar, 2009). Many coal mines are new and, over a 20 to 50-year mine lifespan, the downwind accumulation of U- bearing coal dust warrants investigation. Coal dust from mines and uncovered trucks is affecting traditional herder lifestyles by carpeting livestock grazing areas. The short-term effect is that coal dust in sheep and goat intestines makes sale of coal-blackened sausage casings nearly impossible. The longer-term health effect of consuming meat with U-bearing coal residues requires investigation. Ash from coal combustion is readily airborne, particularly from household ger fires, brick- kilns and heat-only combustion plants. Even with ash-trapping measures, such as electrostatic dust precipitators, some U-bearing ash derived from uraniferous coals becomes airborne from stacks of CHP plants in Ulaanbaatar (Fig.9).

Figure 9 Emissions from the tall stack of CHP Plant No.4 in Ulaanbaatar during January 2011. The stack towers above the photochemical smog that blankets most of the city. In mid-distance is the plume from the main stack of CHP Plant No.3 that failed to rise and is gently descending to the left (west). Having cooled and lost its white vapour cloud is now shedding U-ash to the ground. Photo: Nick Grayson

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Outdoor radiation is monitored by portable scintillation spectrometry at meteorological stations in the provincial centres. Every three months dosimeters are sent by mail to the stations, where they are exposed in instrument shelters at precisely-defined locations. The outdoor absorbed dose rate for 1987-1991 published by Shagjjamba and Zuzaan (2006) are presented in Table 17. Table 17 Outdoor terrestrial gamma dose rate for urban environments in Mongolia, measured by thermoluminescence technique. rank city/town dose rate nGy/h 1 Tsetserleg 119.4 ± 34.5 2 Arvaiheer 110.1 ± 33.0 3 Baruun-Urt 103.5 ± 32.0 4 Bayanhongor 102.0 ± 31.9 5 Uliastai 100.2 ± 31.6 6 Muren 97.2 ± 31.2 7 Undurhaan 96.2 ± 31.0 8 Bulgan 95.3 ± 30.9 9 Sainshand 88.6 ± 29.8 Mongolia mean value 86.9 ± 15.0 10 Ulgii 86.7 ± 29.4 11 Ulaanbaatar 85.3 ± 29.3 12 Mandalgobi 83.4 ± 28.9 13 Hovd 82.7 ± 28.8 14 Darkhan 79.4 ± 28.2 15 Sukhbaatar 77.1 ± 27.8 16 Dalanzadgad 76.8 ± 27.7 17 Altai 73.5 ± 27.0 18 Erdenet 72.6 ± 26.9 19 Zuunmod 68.9 ± 26.2 World mean value 55 The average dose rate of 86.9nGy/hour for Mongolia’s urban areas is higher than the 55 nGy/hour average for the Earth. Tsetserleg, Arvaiheer, Baruun-Urt, and Uliastai exceed 100 nGy/hour, higher than the dose rates mapped across North America by Duval et al. (2005).

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5 Radon 5.1 Radon in water

A method for measuring radon activity in water by liquid scintillator was devised by Norov et al. (1998). Later, Oyunchimeg et al. (2006) presented three simple methods of calculating radon dose from water: HP-Ge gamma spectrometer, Packard liquid scintillator and solid state nuclear track detector with Tastrak film. Norov (2006) authored the Mongolian National Standard MNS 5632:2006 for radon measurement in water by gamma spectral analytical method. The research team concluded that radon levels in tap water of apartments from the Ulaanbaatar municipal groundwater supply is typically 75 Bq/litre (Oyunchimeg, 2006). As shown by Table 18, this is 3 times the maximum recorded for 28,000 domestic water supplies of the USA (Irwin, 1997), 150 times greater than the WHO screening level 0.5 Bq/litre for drinking water “below which no further action is required” (WHO 2011a). Indeed, Ulaanbaatar domestic supply (75 Bq/L) falls just within the definition of “radon mineral waters” (74 Bq/L). Table 18 Radon levels in groundwater in Mongolia and elsewhere in the world, compared with guideline limits of the World Health Organisation (WHO) and national agencies. Radon Radon Location spring longitude latitude Source min max Bayanzurkh 97 20 00 49 07 00 - 518 Bq/L Tsagaan gol 88 00 00 48 53 00 7.4Bq/L 518 Bq/L Urtgad 99 50 00 51 39 00 3.6 Bq/L 222 Bq/L Bulgan 91 23 00 46 35 00 3.6 Bq/L 222 Bq/L GIC (2003) Mongolia Tsetsuukh 99 02 00 48 21 00 3.6 Bq/L 222 Bq/L 11.1 Zaart 98 46 00 48 21 00 177 Bq/L Bq/L Khukh nuden 114 49 00 49 40 00 44 Bq/L 159 Bq/L Oyunchimeg et al. mineral spring water 110 Bq/L (2006) Japan provisional (emergency) standard for infants – applicable to 100 Bq/L drinking-water used to prepare baby food WHO FAQ (2011) World guideline of Codex Alimentarius for infant food 100 Bq/L WHO (2011a) Table World guidelines for radon limit before treatment of water 100 Bq/L A6.1 Oyunchimeg et al. Ulaanbaatar apartment tapwater from public supply pump houses 75 Bq/L (2006) World above this limit, classified as radon mineral water 74 Bq/L Zdrojewicz et al. (2006) Oyunchimeg et al. Mongolia drinking water in some province and soum centres 53 Bq/L (2006) USA maximum of over 28,000 domestic water supplies 24 Bq/L Irwin (1997) “Screening levels for drinking-water WHO (2011a) World below which no further action is required” 0.50 Bq/L USA average of 55,000 ground waters 0.12 Bq/L Irwin (1997) USA average of 35,000 surface waters 0.04 Bq/L Ulaanbaatar groundwater locally exceeds WHO guidelines for uranium in drinking water (Nriagu et al., 2012), suggesting radon levels in tap water will locally exceed the 100 Bq/litre guidelines and so require treatment (Table A6.1 in WHO, 2011a). 38

5.2 Radon in air – outdoors

Outdoor radon emanates from the ground as a decay product of radium-226, a decay product of uranium-238. We suggest that outdoor levels of 222Rn involve interplay of six factors: i) distribution and concentration of geological 238U and 222Rn; ii) gas transmissivity and storage capacity of rocks, subsoil and topsoil; iii) sealing of gas migration paths by water, ice cover, naled ice and permafrost; iv) seasonal and diurnal variations in air temperature; v) fluctuations in air pressure due to meteorological changes; and vi) the half-life of 222Rn being only 3.82 days. The border of north-west Mongolia has an unusually high 222Rn flux (Svegvary et al., 2006), whereas the outdoor levels of radon in Ulaanbaatar detected by Erdev and Munkhtsetseg (2007) are modest. Skin cancers are known to be predominantly due to ultraviolet radiation in bright sunlight (Lucas et al., 2006), such as all-year-round in Mongolia. But radon may also be involved. Henshaw et al. (2001) reported Tastrak film placed horizontally outdoors in England suffered damage from alpha tracks from radon222and its polonium daughters (218Po and 214Po).Peak counts of218Po and 214Po occurred during rainfall and wet deposition of polonium on skin may increase the radiation dose to the skin’s vulnerable basal layer. Henshaw et al. (2001) speculated if 10% of time is spent outdoors, then 2% (range 1-10%) of non-melanoma (common) skin cancers may be linked to settling of polonium aerosols on skin, rising to 30% if time outdoors is continuous. Later workers reported alpha peaks during heavy rain due to washing out of radon daughters 214Bi and 214Pb both with very short half-lives, 19.7 and 26.9 minutes respectively (Greenfield et al., 2008). In Japan, high deposition of radon decay products is associated with convective rainfall from air masses travelling long-distance from the Asian landmass (Yamazawa et al., 2007). 5.3 Radon in air – indoors 5.3.1 Radon in gers It is believed the structure of the ger, the Mongolian national felt tent dwelling, cannot accumulate significant levels of radon (Gerbish et al., 2001), a view supported by 8.2-12.9 Bq/m3measurements reported by Erdev and Munkhtsetseg (2007).Further studies are warranted for four reasons: i) the preferred heating fuel are U-bearing coals from Nalaikh, Baganuur and Shive Ovoo; ii) recent studies show gers accumulate high levels of carbon monoxide and other harmful gases; iii) air enters through the felt walls and door, and exits by warm updraft through the hole in the roof around the hot stove pipe, but radon is the densest gas and may not vent skywards; iii) an urban ger is in its own fenced hashaa where U-bearing ash is spread daily but the ger is shifted from time-to-time in the hashaa and may rest on decades-worth of accumulated U-bearing ash; and iv) an extra layer of felt insulation is added to the ger for winter, and soil is heaped around the rim of the ger to exclude draughts.

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5.3.2 Radon in apartments Radon was monitored in a hundred Soviet apartment flats in Erdenet and Ulaanbaatar in 1994-1996 by passive differential solid state nuclear tracks detectors (SSNTD). Gerbish et al. (2001) reported a marked seasonal difference was apparent, with 12-37 Bq/m3 in summer and up to 40-100 Bq/m3 in winter. Two hundred control points in dwellings in Ulaanbaatar were monitored for radon in 2000- 2002 by SAC-4 scintillation counter. Erdev and Munkhtsetseg (2007) reported wooden homes had the lowest levels (18.7-19.3 Bq/m3, brick homes had intermediate levels (35.6-36.4 Bq/m3) and concrete apartments had the highest levels (41.9-42.6 Bq/m3). However Ulaanbaatar is a large sprawling city on uranium-bearing groundwater, so radon hotspots might be expected. For instance, in autumn 2012 we recorded 70-245 Bq/m3 in a Soviet concrete-frame brick- walled apartment above a shop on Peace Avenue using a Corentium ‘Canary’ alpha monitor. In general, readings are well below the World Health Organisation guidelines of for indoor radon exposure to radon that were recently halved to 100 Bq/m3 (WHO, 2009). Accordingly the Mongolian National Standard MNS 5627:2006 ‘Permissive Radon concentrations' level in homes’ (Norov,2006) merits review. Further surveys are needed as Ulaanbaatar is experiencing a construction boom that over the last decade has consumed several million tonnes of U-bearing ash and clinker in cement, concrete beams and concrete slabs, and in cement blocks for internal walls. Concern is warranted regarding the unknown levels of radionuclides in the large amounts of fired clay bricks, gypsum, plaster, plasterboard, aggregate and slabs of polished ‘granite’ in the on-going construction boom.

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6 Discussion

The data reported in this review enables geochemical pathways for uranium and fluoride to be postulated, so guiding exploration, mining and mine closure activities and identifying threats to the environment. To explain why Mongolia has so many soda lakes, and why some are uraniferous, we propose ‘The Soda-U Model’presented in Fig.10.

Figure 10 Generalised pathways in Mongolian soda lake environments, according to the proposed ‘Soda-U Model’. The Soda-U Model proceeds from left to right, commencing with the generation of calcium- dominant bicarbonate waters. Migrating by gravity towards the basin interior, these waters become gradually depleted of Ca2+ ions that are sequestrated as geopetal crusts (see Fig. 4). In time this tendency to lose Ca2+ ions is sufficient for Na+ to dominate sufficient for sodic soils, sodic groundwater and soda lakes to be inevitable. As a consequence, the pH become strongly alkaline and the fluids leach uranium from U-source rocks across the basin.

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To explain why Mongolian rural communities dependent on shallow wells for drinking water in fluorspar districts are vulnerable to dental fluorosis, we propose ‘The Soda-F Model’ presented in Fig. 11.

Figure 11 Generalised fluoride pathways in fluorspar districts of rural Mongolia, according to the proposed ‘Soda-F Model’. The Soda-F Model proceeds from left to right, and differs from the Soda-U model by the depletion of Ca2+ ions continuing to virtual elimination. This extreme situation appears possible in shallow soils. Stripped of Ca2+ ions as buffer, fluorite in the uppermost couple of metres of fluorspar veins becomes vulnerable to slow leaching by the strongly alkaline waters, resulting in fluoride waters that result in endemic dental fluorosis. To explain why Mongolians in urban areas burning U-bearing coals for heating and electricity are vulnerable to poisoning by uranium and other heavy metals, and lung cancer from radon decay products, we propose ‘The Coal-U Model’ presented in Fig. 12.

Figure 12 Generalised uranium pathways in coal combustion systems in Mongolian urban areas, according to the proposed ‘Coal-U Model’. The Coal-U Model proceeds from left to right, from U-bearing coal to U-bearing ash. Depleted of volatiles by combustion, the resultant ash has elevated U-levels from 4 to 8 times (median x5) greater than the parent coal (see Table 4). The uranium may be leached from the dumped ash and become a risk to drinking water supplies, or remain in the ash that is mined for construction materials and become a risk to indoor air quality by radon emission. 42

To illustrate the complexity of uranium pathways in Ulaanbaatar, we propose ‘The Ulaanbaatar-U Model’ presented in Fig. 13.

Figure 13 Generalised uranium pathways in Ulaanbaatar associated with groundwater, according to the proposed ‘Ulaanbaatar-U Model’. Uranium pathways in Ulaanbaatar are of particular importance for human health as 50% of the Mongolian population live in the capital city and depend on groundwater for drinking water. The Ulaanbaatar-U Model highlights five possible sources for the uranium and radon (Fig.13). Recent mapping (Imaev et al., 2012) shows Ulaanbaatar to occupy an active fault zone that reactivates Neogene and Cretaceous transtensional graben basins. Such settings are likely to contain soda paleo-lakes and coals at depth, favourable to sediment-hosted uranium.

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7 Conclusions

The geological significance of this study is the presentation of new regional geochemical models for uranium and fluoride that will have wide applications in the exploration and delineation of uranium and fluorspar deposits and occurrences. In addition, the prediction of the large unconventional uranium resources in Mongolia’s soda lakes and coals is of major economic geology significance. The geomorphologic significance of this study lies is in drawing attention to the widespread geopetal carbonate crusts that sequestrate Ca2 from groundwater to leave Na+ carbonate/bicarbonate as the dominant ions in the groundwater, so ensuring thousands of soda lakes will form and endure. The ecological significance of this study lies in highlighting the exceptionally high productivity of Mongolia’s soda lakes and their remarkable alkaline extremophile ecosystems. The health significance of the study is in raising awareness of policy makers and developers – and not least citizens – of elevated uranium and radon levels in Ulaanbaatar, and in raising awareness of uranium, arsenic, selenium and fluoride levels and contamination issues in rural areas. a. There is a wide regulatory significance of the study through justifying: b. A review of Environmental Impact Assessments (EIAs) of all coal mines both planned and operational, and likewise for all coal-fired power stations. This is needed so that Government regulators can insist the EIAs are amended to include assessments for each coal, and its ash, of the contents, of uranium, arsenic, selenium and other heavy metals (chromium, cadmium, lead, zinc etc.), as well as fluoride. c. A review of all EIAs for cement, concrete, brick and tile manufacturing plants regarding uranium contents of ash, clinker, clay and aggregate, and testing of products for radon. d. The need for urgent updating of Mongolian National Standards (MNS) to meet the revised WHO guidelines for indoor radon levels. e. An initiative to subject all bottled and canned water and beverages to independent resampling and testing for uranium, arsenic, selenium and fluoride by independent laboratories and for the relevant ministry to publish the results and, where necessary, to shut down hazardous wells. Acknowledgements

We greatly appreciate the improvements to the manuscript by Dr. Peter McNeil, independent UK consultant. Nick Grayson gave invaluable support in the fieldwork and photography. Minjin Batbayar conducted much of the fluorspar fieldwork. Ms. Jambaldorj Uramgaa of Sans Frontiere Progres NGO scoured the State Geofund archives for data. This study was made possible by the financial support of Eco-Minex International Ltd (EMI) of Mongolia.

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