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Extremely high concentrations of uranium (U) were discovered in shallow, groundwater-fed hyperalkaline soda lakes in Eastern
Mongolia. A representative groundwater sample in this area is dilute and alkaline, pH=7.9, with 10mM TIC and 5mM Cl−. In contrast, a representative lake water sample is pH~10 with TIC and Cl− each more than 1,000mM. Groundwat...
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... locations and field parameters are summarized in Table 2. Water temperatures in well samples ranged from 4.4 to 13.9°C (measured at the well bottom by electrode method), while the stream was 26.6°C. ...
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... groundwater and the stream were dilute (SC 1,430-3,192 lS). DO varied widely ranging from below detection to 0.22 mM L -1 (approximate atmospheric saturation) ( Table 2). Concentrations of DO measured by gas chromatography are consistent with but somewhat lower than values measured in the field by elec- trode and colorimetric methods. ...
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... a more reactive ferrihydrite as the ferric oxide solid phase the calculated pe would range from 2.5 to 1.0, and U is spe- ciated entirely as the mobile uranyl ion. Using the U ?4 /U ?6 couple with uraninite and coffinite as the equilibrium solid phases yields an intermediate pe value ranging from -0.3 to -0.6 (Table 2). Using this pe, U is speciated as U ?6 , arsenic is speciated *80% as the reduced As(OH) 3 , and iron and manganese are both speciated overwhelmingly as the reduced ?2 ...
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... Recent discoveries based on the analysis of chemical compositions of fluid inclusions using inductively coupled plasma-mass spectrometry (ICP-MS; Byrne and Kim, 1990;Ho et al., 2010;Wang et al., 2014a) have confirmed that metal-rich fluids (containing U, Y, REEs, and Cu; Wilkinson et al., 2009;Richard et al., 2010Richard et al., , 2012Richard et al., , 2016Richter et al., 2018;Chi et al., 2019) existed in sedimentary basins during the period of related mineralization. Numerous studies have reported that saline lakes have unusually high concentrations of trace metals (e.g., Carpenter et al., 1974;Kharaka et al., 1987;Zheng et al., 1989;Kasedde et al., 2014), such as the ephemeral Lake Merouane Chott in North Africa (U, Cr, Cu, Co, Pb, and Zn; e.g., Hacini and Oelkers, 2010) and various soda saline lakes in Mongolia (U, Co, and Ni; e.g., Volkova, 1998;Linhoff et al., 2011;Shvartsev et al., 2014). However, investigations of the relationship of these brines with ore-forming fluids of basin-related mineralization are limited (e.g., Kharaka and Thordsen, 1992;Breit et al., 2001;Richard et al., 2013Richard et al., , 2016. ...
... Across Inner Mongolia, annual rainfall increases from 100 to 400 mm from northwest to southeast (Tao and Chen, 1987;Domrös and Peng, 1988;Jiang et al., 2006). >100 saline lakes sourced from carbonate-rich groundwater discharge are developed in eastern Mongolian Plateau (Linhoff et al., 2011) and undergo yearround intense evaporation. Several lakes have been reported as having high pH and high concentrations of dissolved trace metals (U, Co, Ni, and Cu;Linhoff et al., 2011). ...
... >100 saline lakes sourced from carbonate-rich groundwater discharge are developed in eastern Mongolian Plateau (Linhoff et al., 2011) and undergo yearround intense evaporation. Several lakes have been reported as having high pH and high concentrations of dissolved trace metals (U, Co, Ni, and Cu;Linhoff et al., 2011). Our samplings of saline lakes are distributed in the Hailar Basin in the northern part of Inner Mongolia, the Eren Basin in the central part, and the Ordos Basin in the southern part (Uyeda and Kanamori, 1979;Tian et al., 1992;Ren, 1995;Northrup et al., 1995). ...
Research into mineralization using a deposit-centric approach has identified three principal factors (evolution of the hydrosphere–atmosphere, secular decrease in global heat production, and long-term global tectonic trends) that have influenced the global pattern of metallogenesis. However, these factors do not explain the peak occurrences of basin-related mineralization during particular periods of Earth’s evolution. Here we shift the research perspective from an ore-deposit-centric approach to one focusing on the formation processes of ore-forming fluids by using mass spectrometry to analyze the concentrations of metallic elements (U, Cr, Fe, Mn, Co, Ni, Cu, Mo, Cd, Sn, Pb, Zn, and V) of naturally occurring saline water bodies (brines) in currently developing basins in China. Our aim is to determine the presence of metal-bearing fluids and establish the formation processes of ore-forming fluids that can subsequently generate mineral deposits. The concentrations of trace metals in evaporated seawater and surficial saline waters (brines) in continental basins can reach up to mg/L level, with the increase in salinity resulting from the significant evaporation that occurs in semi-arid to arid environments. The high salinities increase the density of metal-bearing brines, which in turn causes these brines to circulate and mix with groundwater, resulting in enriched metal element concentrations in the groundwater. Groundwater containing dissolved evaporites also shows relatively high concentrations of metal elements (up to mg/L level) that compare with fresh groundwater. These metal-bearing brines can be regarded as the initial ore-forming fluids of basin-related mineral deposits, such as unconformity-type U deposits, red-bed Cu deposits, and some stratiform Pb–Zn deposits. The metal-bearing brines are the result of substantial evaporation under arid to semi-arid climates. Therefore, we conclude that climate is an important control on the formation of basin-related mineralization and that the tectonoclimatic setting plays an essential role in the formation of metal-bearing brines in closed inland basins. The major climatic events, such as the snowball and greenhouse event can affect the basin-related mineralization globally. The super mantle plume event could affect the global basin-related mineralization by changing the global climate significantly.
... The uranium concentrations ranged from 25.5 µg/L in August 2018-611 µg/L in September 2020 (Fig. 3g-l). These high U concentrations are consistent with the U concentrations reported in other Mongolian saline lakes (Isupov et al., , 2011Linhoff et al., 2011;Shvartsev et al., 2014). Relatively high concentrations of uranium have also been found in saline lake waters in the Ol`khon region of Siberia (~60.6 µg/L) and northwestern China (~35 µg/L) (Chabaux et al., 2011;Zhang et al., 2019;Zhao et al., 2020), although these concentrations were lower than those in this study. ...
The shrinkage of inland, alkaline, and saline lakes has caused the elevation of arsenic and uranium concentrations in lake water. However, the chemical reactions associated with these enrichments remain unclear. We conducted a five-year study of the water chemistry of Orog Lake (Mongolia) and the chemical and spectroscopic characteristics of the sediment to determine the geochemical behavior of arsenic and uranium during evaporation. The arsenic and uranium concentrations increased as evaporation caused the lake to shrink. The maximum concentrations of arsenic and uranium exceeded 200 µg/L and 600 µg/L, respectively, when the lake area was the smallest. Comparisons of the monitoring results with predictions of geochemical modeling suggested that some arsenic was removed from the lake water under highly desiccated conditions. Sequential extraction and X-ray absorption near-edge structure analyses showed that ferrihydrite can take up As(V). The accumulation of uranium could be reproduced by considering only evaporation. The conservative behavior of uranium can be explained by the low affinity of U(VI) for carbonate and ferrihydrite at pH > 9 and high dissolved inorganic carbon concentrations. The ubiquitous formation of extremely soluble U-bearing salts after the complete desiccation of inland lakes may thus become a serious threat to limnetic ecosystems.
... Moreover, uranium is a major structural constituent and accounts for almost five percent of all known minerals in the Earth's crust [3]. Uranium occurs in all water sources, and significantly high concentrations have been reported in various locations globally [4], with natural deposits being the main source. In addition, uranium mining and ore processes, as well as the nuclear fuel cycle, increase its concentration in water sources [5]. ...
... Approximately 6000 t of uranium reserves are located in Western Mongolia, which is among the largest in Central Asia [19]. Benjamin, Isupov, and Kolpakova [4,19,20] reported that high levels of uranium in the saline lakes of Western Mongolia were due to the uranium rich groundwater that feeds the lake. Recently, Niragu [21] revealed the high concentration of uranium in the drinking water of Ulaanbaatar city. ...
Traditional methods for determining uranium in groundwater are spectroscopic methods that require time, money, and experienced chemists. A prediction method for predicting uranium concentration using a few hydrochemical parameters that are related to uranium was developed within this study. In this study, uranium, hydrochemical parameters, and trace elements of groundwater around Ulaanbaatar in Mongolia were measured. Inductively coupled plasma mass spectrometry was used to determine the uranium concentration in 135 samples. The relationship between uranium concentration and hydrochemical parameters was studied to determine whether the concentration in groundwater could be predicted using chemometric methods based on some hydrochemical parameters. Chemometric methods were performed using a Python programming language. A pattern recognition method for classifying groundwater samples by specific threshold uranium concentration uses a principal component analysis (PCA) and support vector machine (SVM). The average accuracy of the classification models was 88.21%. PCA is used to visualize the classification by uranium concentration and show which hydrochemical parameters are crucial to predicting uranium concentration. In this study, a regression model was developed to predict uranium concentration in groundwater using hydrochemical parameters selected by the PCA-SVM combination method. The regression method uses a combination of polynomial regression and multiple linear regression. This combined regression method has shown good results for predicting uranium concentrations based on selected hydrochemical parameters.
... The uranium concentrations ranged from 25.5 µg/L in August 2018-611 µg/L in September 2020 (Fig. 3g-l). These high U concentrations are consistent with the U concentrations reported in other Mongolian saline lakes (Isupov et al., , 2011Linhoff et al., 2011;Shvartsev et al., 2014). Relatively high concentrations of uranium have also been found in saline lake waters in the Ol`khon region of Siberia (~60.6 µg/L) and northwestern China (~35 µg/L) (Chabaux et al., 2011;Zhang et al., 2019;Zhao et al., 2020), although these concentrations were lower than those in this study. ...
... The relationship with pH is likely related to the acidity of the water or other chemicals for which pH is a proxy, resulting in a set of limiting factors potentially leading to the death of individuals in case of relatively weak variations in values (Clark and Lazerte 1985;Horne and Dunson 1995). Sensitivity to pH and other variations in water parameters, such as TDS (here correlated with all other variables) and salinity (here correlated with pH), may be linked to the mineral salts present in large concentration in the region and leaching into the environment, as well as pollutants of human origins (Linhoff et al. 2011;Afonina and Tashlykova 2018). In addition, greater changes are expected in the near future as global changes, locally resulting in an increase in the rate of desertification and thus linked environmental variables, are becoming increasingly prominent threats (Shnitnikov 1975;Zolotokrylin et al. 2016). ...
The presence of amphibian larvae is restricted by both biotic and abiotic variables of the environment. Some of these variables are still undetermined in the septentrional eastern palearctic where Rana amurensis, Strauchbufo raddei and Dryophytes japonicus are found in large numbers. In this study we sampled 92 sites across Mongolia, Russia and the Democratic People’s Republic of Korea and measured biotic and abiotic water variables as well as the height of flooded terrestrial and emergent aquatic vegetation at the breeding site. We determined that the presence of anuran larvae is generally but not always linked to pH and temperature. Rana amurensis was not significantly affected by any of the variables measured, while S. raddei was impacted by water conductivity and D. japonicus by pH, temperature and vegetation. Our results highlight a potential risk for these species due to the changes in aquatic variables in response to desertification.
... μmol/L in groundwater; from wells Li concentration is 1.8-6.93 μmol/L (Linhoff et al. 2010). In Southern Mongolia, Cretaceous oil basins could be other areas for research and exploration. ...
Rare metal ore deposits and occurrences of Sn-W and W-Mo-Be greisen/stockwork and vein-type, Sn-polymetallic skarn, Sn placers, sedimentary Li, Li-bearing Li-F granites, pegmatites, and ongonites are mainly associated with late Triassic-early Jurassic and Middle Jurassic-early Cretaceous highly differentiated granites and are well-known in Eastern Mongolia, Mongolian Altai, and South Mongolia. Commercial tin deposits occur as small- and medium-sized eluvial and alluvial placers sourced from Sn-W greisen and vein deposits. Many of the Sn-W greisen/stockwork and quartz vein and placer deposits were mined in the last century. Beryllium-bearing pegmatites are common, but Be is mainly a by-product of W-Mo deposits. Other Be resources could be Be-bearing tuffs in Cretaceous volcanic rocks. Lithium is known to occur in pegmatites; however a recent discovery was made of a new type of sedimentary lithium deposit. Other future sources of Li could be Li-F granites and Li-ongonite. The Li-F-bearing granites also contain Ta and Nb; the latter is known from Nb-Zr-REE deposits associated with alkaline rocks in Lake zone of Western Mongolia.
... Zhang [22] found that, in the mining of lithium, boron, potassium, and magnesium from the Qaidam Basin, both uranium and thorium could be enriched, meaning that uranium enrichment is one of the basic characteristics of the saline lakes of northwestern China. The concentration of uranium of soda lakes in Mongolia is 57~15,000 µg/L [23], 320 µg/L in Gasikule salt lake in Qaidam Basin [24], and 13.4 µg/L in Qinghai Lake [25]. The potential mechanism of high uranium content in a saline lake has also been explored. ...
... The potential mechanism of high uranium content in a saline lake has also been explored. For example, Benjamin et al. [23] and Isupova et al. [26] found that there exist high concentrations of uranium(U) in soda lake basins with groundwater-fed hyperalkaline. Hence, uranium-rich groundwaters are concentrated by evaporation and the U(VI) is chelated by CO 2− 3 to form the highly soluble UO 2 (CO 3 ) 4− 3 in water, which is the main cause of the enrichment of uranium content in lakes in northwestern Mongolia. ...
Four saline lakes in the northeast of Qaidam Basin were selected to explore the distribution characteristics and influencing factors of uranium isotopes in lake waters with high evaporation background. The 238U concentration and the activity ratios of 234U/238U ([234U/238U]AR) showed that there was no significant change in the same lake, but there was a certain degree of difference in the distribution between different lakes. We found that aqueous 238U concentration within a certain range increased with an increase in TDS (total dissolved solid) and salinity, as was also the case with pH. As in natural waters, the pH affects the speciation of 238U, but TDS and salinity affect the adsorption process of aqueous 238U. Further, the replenishment of water will also affect the uranium isotope concentration for lakes, but it is not the main influencing factor for saline lakes. Therefore, we suggest that pH is the dominant factor affecting changes in aqueous 238U concentration of the sampled saline lakes. The [234U/238U]AR in these saline lakes are closely related to the input water and the associated water–rock interactions involving sediments, atmosphere dust, and organic material, etc. during the evolution stage, metamorphous degree, and hydrochemistry of the saline lakes. Lake water samples collected in the maximum and minimum discharge water period, were used to evaluate the seasonal distribution characteristics of aqueous 238U, and we found that 238U concentration did not show an evident change with the seasons in these saline lakes. If the 238U concentration and [234U/238U]AR can remain consistent during a period of time, then the sediment ages and/or sedimentation rates could be determined by lake sediment and/or biogenic carbonate in future, thus allowing for the accurate reconstruction of the paleoclimate and paleoenvironment.
... Broecker's hypothesis is grounded in studies of the [U] of highly alkaline Mono Lake, which has both [CO 3 2À ] and [U] $100 times greater than seawater (Thurber, 1965;Anderson et al., 1982;Simpson, 1982). Similarly high U concentra-tions have been observed in alkaline surface waters of Eastern and Western Mongolia (Linhoff et al., 2011;Shvartsev et al., 2012). According to Broecker (1971) and Broecker (2013), observations of the correlation between [U] and [CO 3 2À ] in alkaline lakes suggest that an increase in seawater [CO 3 2À ] could be accompanied by a proportional increase in seawater [U]. ...
We measured U/Ca ratios, ^4He concentrations, ^(234)U/^(238)U, and ^(238)U/^(235)U in a subset of well-preserved aragonitic scleractinian fossil corals previously described by Gothmann et al. (2015). Comparisons of measured fossil coral He/U ages with the stratigraphic age demonstrate that well-preserved coral aragonite retains most or all of its radiogenic He for 10’s of millions of years. Such samples must be largely or entirely free of alteration, including neomorphism. Measurements of ^(234)U/^(238)U and ^(238)U/^(235)U further help to characterize the fidelity with which the original U concentration has been preserved. Analyses of fossil coral U/Ca show that the seawater U/Ca ratio rose by a factor of 4-5 between the Early Cenozoic and today. Possible explanations for the observed increase include (1) the stabilization of U in seawater due to an increase in seawater [CO_3^(2-)], and a resulting increase in UO_2-CO_3 complexation as originally suggested by Broecker (1971); (2) a decrease in the rate of low-temperature hydrothermal alteration from Early Cenozoic to present, leading to a diminished U sink and higher seawater [U]; or (3) a decrease in uranium removal in reducing sediments, again leading to higher seawater [U].
... The relationship with pH is likely related to the acidity of the water or other chemicals for which pH is a proxy, resulting in a set of limiting factors potentially leading to the death of individuals in case of relatively weak variations in values (Clark and Lazerte 1985;Horne and Dunson 1995). Sensitivity to pH and other variations in water parameters, such as TDS (here correlated with all other variables) and salinity (here correlated with pH), may be linked to the mineral salts present in large concentration in the region and leaching into the environment, as well as pollutants of human origins (Linhoff et al. 2011;Afonina and Tashlykova 2018). In addition, greater changes are expected in the near future as global changes, locally resulting in an increase in the rate of desertification and thus linked environmental variables, are becoming increasingly prominent threats (Shnitnikov 1975;Zolotokrylin et al. 2016). ...
... Концентрации мышьяка до 115-234 мг/л были обнаружены в вулканическом высокоминерализованном озере Диамант (Аргентина) при минерализации 270 г/л [5]. В содово-соленых озерах Централь- ной Азии были определены повышенные кон- центрации мышьяка (0.5-2.4 мг/л), селена (2- 2.3 мг/л) и урана (до 14 мг/л) [1,2,4]. ...
