Hydrochemical evolution of Na-SO^sub 4^-Cl groundwaters in a cold, semi-arid region of southern Siberia

The Shira region of Khakassia in southern Siberia exhibits many features governing the evolution of groundwater and surface-water chemistry that are common to other cold, semi-arid areas of the world: (1) a continental climate, (2) location in a rain shadow, (3) low density of surface-water drainage...

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Bibliographic Details
Published in:Hydrogeology journal 1999-12, Vol.7 (6), p.546
Main Authors: Parnachev, V P, Banks, D, Berezovsky, A Y, Garbe-schönberg, D
Format: Article
Language:English
Subjects:
Arid zones
Gypsum
Mineralization
Salt lakes
Semiarid lands
Sewage
Sodium sulfate
Soil profiles
Sulfates
Surface water
Water chemistry
Water table
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Summary:The Shira region of Khakassia in southern Siberia exhibits many features governing the evolution of groundwater and surface-water chemistry that are common to other cold, semi-arid areas of the world: (1) a continental climate, (2) location in a rain shadow, (3) low density of surface-water drainage, (4) occurrence of saline lakes, and (5) occurrence of palaeo- and modern evaporite mineralisation. In lowland areas of Shira, the more saline groundwaters and lake waters have a sodium-sulphate (-chloride) composition. Results of thermodynamic modelling suggest that these evolve by a combination of silicate weathering and gypsum and halite dissolution, coupled with carbonate precipitation to remove calcium and bicarbonate ions. An approximately 1:1 sodium:sulphate ratio occurs even in groundwaters from non-evaporite-bearing aquifers. This may indicate the formation of secondary sodium sulphate evaporites (in or near saline lakes or in soil profiles where the water table is shallow), which are subsequently distributed throughout the study area by atmospheric transport. Several urban groundwaters are characterised by very high nitrate concentrations, conceivably derived from sewage/latrine leakage.[PUBLICATION ABSTRACT]
ISSN:1431-2174
1435-0157
DOI:10.1007/s100400050228