Western Siberia is a unique territory where more than 12000 water reservoirs are located. The region is characterized by high bogginess up to 90% in the north. Bog and lake systems are able to accumulate natural and technogenic resources, including trace elements and organic matter. The article presents the results of a surface water chemical composition along a 5-year monitoring. The obtained data allow concluding that dynamics of water chemistry is predetermined by their location in various landscape zones and subordinated to zonal distribution of such major landscape elements as moistening, evaporation, rate of groundwater flow, etc.
The investigated Mongolian lakes are marked by a large range of trace element concentrations even in very small geographical areas. This work includes the data on major and trace element concentrations along of a series of samples collected in 2009 and 2012. Three geochemical types of lakes have been distinguished within the study area: (1) alkaline soda lakes, (2) chloride lakes with pH < 9.0 and Na-Cl-dominated composition, and (3) sulfate ones with pH < 8. The soda lakes show high concentrations of As, U, F and relatively low salinity. The chloride lakes have higher salinities and one of them was the most saline of all the lakes (Davsan Nuur). These lakes have higher concentrations of Li (up to 82.1 mg/L), Rb (up to 1350 mg/L), Br and Sr. Sulfate rich lakes are far less common in the area. Characteristic trace elements are Mo, Al and Sr. Thermodynamic modeling at 25°C and 1 bar total pressure was performed with the “HCh” code. We considered mineral and solution equilibria in soda lake waters and calculated the main uranium and arsenic species in solutions and bottom sediments of Shaazgay-Nuur lake to offer a possible way of As removal as an undesirable impurity in commercial products.
Major ion and trace elements chemistry of fifty-eight water samples of southern part of Western Siberia (Russia) were analysed with a suite of statistical techniques (using R programming language), in an effort to explain the key processes affecting chemical composition of saline lakes. The database included data about well, river, and lake waters and groundwater. According to performed cluster analysis of chemical data, all lakes in the area can be divided in to 5 main groups and their chemical composition very similar to rivers and deep groundwater. Shallow groundwaters are more enriched in Ca 2+ and Mg 2+ . Principal component analysis (PCA) identified four main principal components, with the first principal component (PC1) accounting for 44.3% and representing the process of salinization, and PC2 and PC3 (17.9 and 8.6% of total variance) controlled by water-rock interaction process of carbonates/sulphates precipitation and aluminosilicates formation.
The aim of this study is to evaluate the definition of water chemical type, with particular attention to soda brine characteristics by assessing ionic composition and pH values on a large geographic scale and broad salinity (TDS) range of Eurasian inland saline surface waters, in order to rectify the considerable confusion about the exact chemical classification of soda lakes and pans. Data on pH and on the concentration of eight major ions were compiled into a database drawn from Austria, China, Hungary, Kazakhstan, Mongolia, Russia, Serbia, and Turkey. The classification was primarily based on dominant ions exceeding an equivalent percentage of 25 (> 25e%) of the total cations or anions, and the e% rank of dominant ions was also identified. We identified four major types: waters dominated by (1) Na-HCO3 (10.0%), (2) Na-HCO3 + CO3 (31.4%), (3) Na-Cl (45.9%), and (4) Na-SO4 (12.7%), considering only the first ion by e% rank. These major types can be divided into 30 subtypes in the dataset, taking into account the e% rank of all dominant ions. The major and subtypes of soda brine can be divided into "Soda" and "Soda-Saline" types. "Soda type" when Na+ and HCO3- + CO3(2-) are the first in the rank of dominant ions (> 25e%), and "Soda-Saline type" when Na+ is the first in the rank of dominant cations and the sum of HCO3- + CO3(2-) concentration exceeds 25e%, but it is not the first in the rank of dominant anions. Soda-saline type can be considered as a separate evolutionary stage between Soda and Saline types respect to the geochemical interpretation by saturation indexes of brines. The obtained overlapping ranges in distribution demonstrate that a pH measurement alone is not a reliable indicator to classify the permanent alkaline "soda type" and various other types of temporary alkaline waters.
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