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Lead (Pb) pollution in and around Ulaanbaatar is of national concern, given that the Mongolian capital is home to nearly half of the country's entire population. By comparison, Mongolian countryside is a pristine environment because of its sparse population and low industrial activity. The concentration of Pb in urban soils (average of 39.1 mg kg) was twice the values found (average 18.6 mg kg) in background territories (i.e., Mongolian rural sites). Furthermore, Pb contamination was examined by using Pb stable isotopic composition, and covariance of Pb isotopic ratios showed two groups between rural and urban soils as pristine and disturbed sites. The Pb/Pb ratio, the most prominent fingerprint for Pb pollution, was 1.163-1.185 for the urban whereas values for rural soils (1.186-1.207) were analogue to the regional Pb isotopic signatures. Local coal sources and their combustion products, one of the potential Pb pollution sources in Ulaanbaatar, have significant radiogenic properties in terms of Pb isotopic composition and revealed an average of 1.25 for Pb/Pb and 19.551 for Pb/Pb ratios. Thus, contributions from coal firing activity to Pb pollution lower than it was assumed, and smaller range of these values measured in urban soils may be attributed to the mixing of less radiogenic Pb as a constituent of the leaded gasolines. [ABSTRACT FROM AUTHOR]

Abstract: Distribution of uranium (VI) between soil solids and solutions is a key parameter in assessing the risk to the biosphere of disposing uranium-rich waste products from nuclear plants as well as uranium (U) ore mining. Both of these topics have recently been brought to public attention in Mongolia. Regional background levels of soil elements are an important dataset for accessing the actual environmental situation and monitoring pollution levels. Little information, however, is available on background concentrations of various elements in Mongolian soils. Thirteen rural soils were sampled from six provinces in Mongolia, and the concentrations of macro-, micro- and trace elements were measured. The values obtained served as a reference (baseline) for uncontaminated soils. The soils were characterized with slightly acidic to strongly alkaline pH values. With the exception of the sample from a western province, all the soils investigated contained little organic matter. The content of soil elements did not vary widely among geographical regions. The concentration of most micro elements was within the range of worldwide soil values but the value for Zn tended to be moderately higher. The U (VI) sorption into the soils was investigated using the batch technique and the 237U radionuclide tracer, produced by the photo fission reaction 238U(γ, n) 237U at an electron accelerator. The 237U distribution coefficient (K d), derived from the sorption isotherms, was related to solution pH and varying from 9 to 2547 mL g-1 when the pH ranged between 3 and 7.7. The sorption process was interpreted in terms of the formation of different U (VI) species at given concentrations, calculated using the Speciation program with and without carbonate in the system. The U sorption isotherm displayed two general patterns: one where sorption decreased as solution pH increased, showing a maximum at pH 3, and another pattern revealed an adsorption maximum at pH 5 and then decreased up to pH 7.7 (the final solution pH). The observed decrease in K d when solution pH increased from 6 to 8 was consistent with the increased formation of soluble UO2(OH)2 species. A linear negative correlation between lgK d and the solution pH was observed similarly to that reported for the soils with a pH ≥ 6. [Copyright &y& Elsevier]

Abstract: The physicochemical properties and characterization of some organic matters of peloids from 12 lakes in Mongolia were examined. These peloids belong to the continental hydrosulfide sticky peloid except Gurvan nuur peloid, which was classified as a sapropel with high ash content. The peloid organic matters were investigated using chemical analysis and several analytical techniques, such as IR, and 13C NMR spectroscopy, GC/MS, and gas chromatography. The concentration of total organic carbon in all continental hydrosulfide sticky peloids is ranged from 0.4 to 3.1 mass %, but 15.3 mass % in the sapropel. Thus, the majority of the peloids in Mongolia are hydrosulfide sticky peloids with lower organic content than the sapropel and peat. In this study, no significant differences in the chemical composition were observed between dissoluble and insoluble organic matters from peloids. Some classes of biomolecules, including lipids and carbohydrates, were identified. The biogenic stimulator humic acid was the major part of the peloid organic matter. HA concentration varied between 11% and 56% of total organic matter. The macromolecule of the sapropel HA exhibited a lower aromatization degree and more functional groups than other HAs, as revealed by the 13C NMR data and the C/H ratio. Our results suggested that the presence of known bioactive organic compounds, such as humic acids, lipids, and carbohydrates, as well as hydrogen sulfide, increase the balneological value of peloids in Mongolia. [Copyright &y& Elsevier]