Hydrochemistry of Salt Lakes of the Qinghai-Tibet Plateau, China

Abstract

The authors have carried out scientific investigations of salt lakes on the Qinghai-Tibet Plateau since 1956 and collected 550 hydrochemical data from various types of salt lakes. On that basis, combined with the tectonic characteristics of the plateau, the hydrochemical characteristics of the salt lakes of the plateau are discussed. The salinity of the lakes of the plateau is closely related to the natural environment of lake evolution, especially the climatic conditions. According to the available data and interpretation of satellite images, the salinity of the lakes of the plateau has a general trend of decreasing from north and northwest to south and southeast, broadly showing synchronous variations with the annual precipitation and aridity (annual evaporation/annual precipitation) of the modern plateau. The pH values of the plateau salt lakes are related to both hydrochemical types and salinities of the lake waters, i.e., the pH values tend to decrease from the carbonate type ? sodium sulfate subtype ? magnesium sulfate subtype ? chloride type; on the other hand, a negative correlation is observed between the pH and salinities of the lakes. Geoscientists and biological limnologists generally use main ions in salt lakes as the basis for the hydrochemical classification of salt lakes. The common ions in salt lakes are Ca 2? , Mg 2? , Na ? , K ? , Cl -SO 4 2-, CO 3 2-, and HCO 3 -. In this paper, the KurnakovValyashko classification is used to divide the salt lakes into the chloride type, magnesium sulfate subtype, sodium sulfate subtype and carbonate type, and then according to different total alkalinities (K C = Na 2 CO 3 ? NaHCO 3 /total salt 9 100%) and different saline mineral assemblages, the carbonate type is further divided into three subtypes, namely, strong carbonate subtype, moderate carbonate subtype and weak carbonate subtypes. According to the aforesaid hydrochemical classifications, a complete and meticulous hydrochemical classification of the salt lakes of the plateau has been made and then a clear understanding of the characteristics of N-S hydrochemical zoning and E-W hydrochemical differentiation has been obtained. The plateau is divided into four zones and one area. There is a genetic association between certain saline minerals and specific salt lake hydrochemical types: the representative mineral assemblages of the carbonate type of salt lake is borax (tincalconite) and borax-zabuyelite (L 2 CO 3 ) and alkali carbonate-mirabilite; the representative mineral assemblages of the sodium sulfate subtype are mirabilite (thenardite)-halite and magnesium borate (kurnakovite, inderite etc.)-ulexite-mirabilite; the representative mineral assemblages of the magnesium sulfate subtype are magnesium sulfate (epsomite, bloedite)-halite, magnesium borate-mirabilite, and mirabilite-schoenitehalite, as well as large amount of gypsum; The representative mineral assemblages of the chloride type are carnallite-bischofite-halite and carnallite-halite, with antarcticite in a few individual salt lakes. The above-m...

Spatiotemporal variations of Chinese lakes and their driving mechanisms since the Last Glacial Maximum: A review and synthesis of lacustrine sediment archives

“…From 12.0 to 7.5 cal ka BP, the humidity of the lake area was remarkably improved, as evidenced by the increased pollen concentrations, TOC and TN contents and decreased ostracod δ 18 O. Specifically, two peaks (11.0 and 8.5 cal ka BP) are notable for the pollen concentrations, TOC and TN contents, while the ostracod δ 18 O was generally low from 11.5-7.5 cal ka BP. Multiproxy results based on data synthesized after considering the proxies' different responses to the humidity and temper-ature of the lake area show that the best thermal-humid combination of Lake Qinghai should be at around 8.5 cal ka BP, reflecting the maximal intensification of the East Asian monsoon.…”

“…However, climate for the northern Tibetan Plateau appears to have led to dry conditions, as evidenced by the semiclosed hydrological conditions, lowered water stands and increased water salinities for some lakes in this region, with no discharges of glacial-melting waters. For instance, the diatom assemblages of Lake Sipanguer are characterized by relative increases of benthic and epilithic diatoms, while those of and Zhacang Chaka are characterized by deposited mirabilite and gypsum [18]. For the late Holocene, the climate became drier, as indicated by intense shrinking of Tibetan lakes, as well as vegetation degradation (decreased pollen concentrations and increased relative percentages of dry species/genera) of the lake watersheds.…”

“…Lakes such as Lake Zhacang Chaka had entered the last phase of the salt lake development during this period, and their sediment is mainly composed of mirabilite and halite. Overall, the late Holocene was an important period of salification for Tibetan lakes [18].…”

Assessment of an Increase in Boron and Arsenic Concentrations at the Discharge Area of Na-Borate Mine (Kirka-Eskisehir, Turkey)

“…GW41 that are higher than the allowable limit for drinking purposes. The previous studies have also revealed that As and Sr concentrations in water resources around boron deposit areas are generally higher (Helvaci and Alonso 2000;Helvaci et al 2004;Gemici et al 2008;Zheng and Liu 2009).…”

Origin of boron in the Damxung Co Salt Lake (central Tibet): Evidence from boron geochemistry and isotopes

“…drothermal origin for the boron present in lake deposits (Zheng et al, 1983;Wu et al, 1984;Zhang et al, 1999) based on the dense distribution of geothermal activities and springs in the lakes along activated graben systems (Zheng et al, 1989;Lü et al, 2013). Others interpretations have considered that the high boron concentration of geothermal water could contribute significantly to boron deposits in the nearby internally drained lakes, as suggested by the constant supply of boron from this source into the lakes and the consequent evaporation (Zheng et al, 1983;Wu et al, 1984;Zhang et al, 1999).…”