The hydrochemical features of salt lakes in Qaidam Basin |
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| Authors: | Yu Shengsong |
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| Institution: | (1) Institute of Salt Lakes, Academia Sinica, Xining |
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| Abstract: | There are 37 lakes in the Qaidam Basin: 1 freshwater lake, 6 brackish-water lakes, 2 saline-water lakes and 28 salt lakes.
The pH value of salt lake brines is 7.014 on the average, and the average total mineralization is 340.75 g/1. Their water
bodies belong mainly to the five-component equilibrium system,: Na, K, Mg//SO4, Cl-H2O, which can be further grouped into sodium-magnesium sulfate subtype, magnesium sulfate subtype, chloride transition subtype
and chloride type water by their hydrochemical property. The salt lake brines of the first salt forming epoch (N2−Q3) were of the sulfate type. In the second salt forming epoch (Q3−Q4), some of them were of the chloride type.
The pH value of brines decreases with the increase of total mineralization. The pH value is lower when the total mineralization
is from 50–310 g/l and higher when the total mineralization is from 310–355 g/l, however, when the total mineralization is
higher than 355 g/l, the pH value decreases slowly again.
The total mineralization of the chloride type and the chloride transition subtype brine is higher than the sulfate type, being
310–530 g/l, 310–470 g/l, and less than 355 g/l in that order.
Of the 40 chemical compositions in the saline lake brines in Qaidam Basin, potassium is mainly concentrated in the chloride
type and chloride transition subtype brine, boron and lithium mainly in the sulfate type. Evaporation experiments show that
boron and lithium are accumulated in concentrated brine until crystallization of bischofite takes place. Potassium is also
accumulated in concentrated brine during the salt forming stage, but its concentration decreases with the increase of total
mineralization during the potassium forming stage.
This paper was published in Chinese inOcean. et Limn. Sinica;15 (4):341–359, 1984. |
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