Check out our New Publishers' Select for Free Articles

Aquatic Geochemistry (v.15, #1-2)

Saline Lakes’ Response to Global Change by Abraham Lerman (pp. 1-5).

Thermodynamic and Kinetic Properties of Natural Brines by Frank J. Millero (pp. 7-41).

The physical chemistry of natural brines made up of mostly NaCl has been studied over the years. In this article, the work on the thermodynamics and kinetics of processes in NaCl brines will be examined. The importance of ionic interactions of the processes will be stressed. This will include the pressure–volume–temperature and physical–chemical properties of NaCl and other brine salts from 0 to 6 m, 0 to 200°C, and 0 to 1,000 bar applied pressures. Acid–base, gas–liquid, solid–liquid, and ion–complex formation processes in NaCl are examined. Equations that can be used to estimate the equilibria in NaCl are given. Pitzer models are discussed that can be used to estimate ionic equilibria in brines. The oxidation of Fe(II) and Cu(I) with O₂ and H₂O₂ and the reduction of Cu(II) with H₂O₂ in NaCl are examined in terms of ionic complexes of metals with OH⁻ and CO₃ ²⁻. The oxidation of H₂S with O₂ and H₂O₂ is also examined in NaCl media. Equations are given that can be used to estimate the effect of ionic interactions on kinetic processes in NaCl.

Keywords: Brines; Thermodynamics; Kinetics; Sodium chloride; Redox; PVT properties

Isotopic Evolution of Saline Lakes in the Low-Latitude and Polar Regions by Juske Horita (pp. 43-69).

Isotopic fractionations associated with two primary processes (evaporation and freezing of water) are discussed, which are responsible for the formation and evolution of saline lakes in deserts from both low-latitude and the Polar regions. In an evaporative system, atmospheric parameters (humidity and isotopic composition of water vapor) have strong influence on the isotopic behavior of saline lakes, and in a freezing system, salinity build-up largely controls the extent of freezing and associated isotope fractionation. In both systems, salinity has a direct impact on the isotopic evolution of saline lakes. It is proposed that a steady-state “terminal lake” model with short-term hydrologic and environmental perturbations can serve as a useful framework for investigating both evaporative and freezing processes of perennial saline lakes. Through re-assessment of own work and literature data for saline lakes, it was demonstrated that effective uses of the isotope activity compositions of brines and salinity-chemistry data could reveal dynamic changes and evolution in the isotopic compositions of saline lakes in response to hydrologic and environmental changes. The residence time of isotopic water molecules in lakes determines the nature of responses in the isotopic compositions following perturbations in the water and isotope balances (e.g., dilution by inflow, water deficit by increased evaporation, and/or reduction in inflow). The isotopic profiles of some saline lakes from the Polar regions show that they switched the two contrasting modes of operation between evaporative and freezing systems, in response to climate and hydrological changes in the past.

Keywords: Saline lakes; Isotopic compositions; Evaporation; Freezing; Low-latitude; Arctic; Antarctica; Steady-state; Perturbations

Closed Basin Brine Evolution and the Influence of Ca–Cl Inflow Waters: Death Valley and Bristol Dry Lake California, Qaidam Basin, China, and Salar de Atacama, Chile by Tim K. Lowenstein; François Risacher (pp. 71-94).

Diagenetic-hydrothermal brines, here called “hydrothermal Ca–Cl brines,” have compositions that reflect interactions between groundwaters and rocks or sediments at elevated temperatures. Hydrothermal Ca–Cl brines reach the surface by convection-driven or topographically driven circulation, and discharge as springs or seeps along fault zones to become important inflow waters in many tectonically active closed basins. Case studies from (1) Qaidam Basin, China, (2) Death Valley, California, (3) Salar de Atacama, Chile, and (4) Bristol Dry Lake, California illustrate that hydrothermal Ca–Cl inflow waters have influenced brine evolution in terms of major ion chemistries and mineral precipitation sequences. All four basins are tectonically active; three (Death Valley, Salar de Atacama, and Qaidam Basin) have well-documented Ca–Cl spring inflow and Holocene faulting. Bristol Dry Lake has young volcanic deposits and Salar de Atacama has an active stratovolcano on its eastern margin, indicating subsurface magma bodies. A midcrustal magma chamber has been identified in southern Death Valley. Volcanism and faulting in these closed basins provides the heat source for hydrothermal-diagenetic processes and the energy and pathways to deliver these waters to the surface.

Keywords: Closed basins; Brine evolution; Chemical divide; Qaidam Basin; Death Valley; Salar de Atacama; Bristol Dry Lake; Ca–Cl inflow waters

Geochemical Evolution of Great Salt Lake, Utah, USA by Blair F. Jones; David L. Naftz; Ronald J. Spencer; Charles G. Oviatt (pp. 95-121).

The Great Salt Lake (GSL) of Utah, USA, is the largest saline lake in North America, and its brines are some of the most concentrated anywhere in the world. The lake occupies a closed basin system whose chemistry reflects solute inputs from the weathering of a diverse suite of rocks in its drainage basin. GSL is the remnant of a much larger lacustrine body, Lake Bonneville, and it has a long history of carbonate deposition. Inflow to the lake is from three major rivers that drain mountain ranges to the east and empty into the southern arm of the lake, from precipitation directly on the lake, and from minor groundwater inflow. Outflow is by evaporation. The greatest solute inputs are from calcium bicarbonate river waters mixed with sodium chloride-type springs and groundwaters. Prior to 1930 the lake concentration inversely tracked lake volume, which reflected climatic variation in the drainage, but since then salt precipitation and re-solution, primarily halite and mirabilite, have periodically modified lake-brine chemistry through density stratification and compositional differentiation. In addition, construction of a railway causeway has restricted circulation, nearly isolating the northern from the southern part of the lake, leading to halite precipitation in the north. These and other conditions have created brine differentiation, mixing, and fractional precipitation of salts as major factors in solute evolution. Pore fluids and diagenetic reactions have been identified as important sources and especially sinks for CaCO₃, Mg, and K in the lake, depending on the concentration gradient and clays.

Keywords: Lakes; Saline; Evaporation; Mixing; Calcium bicarbonate; Sodium chloride; Precipitation; Re-solution; Halite; Mirabilite; Calcite; Dolomite; Mg-silicate; Diffusion; Pore-fluids; Diagenesis; Climate

Origin of Salts and Brine Evolution of Bolivian and Chilean Salars by François Risacher; Bertrand Fritz (pp. 123-157).

Central Andes in Bolivia and northern Chile contain numerous internal drainage basins occupied by saline lakes and salt crusts (salars). Salts in inflow waters stem from two origins: alteration of volcanic rocks, which produces dilute waters, and brine recycling, which leads to brackish waters. Chilean alteration waters are three times more concentrated in average than Bolivian waters, which is related to a higher sulfur content in Chilean volcanoes. Brackish inflows stem from brines which leak out from present salars and mix with dilute groundwater. Most of the incoming salts are recycled salts. The cycling process is likely to have begun when ancient salars were buried by volcanic eruptions. Three major brine groups are found in Andean salars: alkaline, sulfate-rich, and calcium-rich brines. Evaporation modeling of inflows shows good agreement between predicted and observed brines in Chile. Alkaline salars are completely lacking in Chile, which is accounted for by higher sulfate and lower alkalinity of inflow waters, in turn related to the suspected higher sulfur content in Chilean volcanic rocks. Six Bolivian salars are alkaline, a lower number than that predicted by evaporative modeling. Deposition on the drainage basin of eolian sulfur eroded from native deposits shifts the initial alkaline evolution to sulfate brines. The occurrence of calcium-rich brines in Andean salars is not compatible with volcanic drainage basins, which can only produce alkaline or sulfate-rich weathering waters. The discrepancy is likely due to recycled calcic brines from ancient salars in sedimentary basins, now buried below volcanic formations. Calcic salars are not in equilibrium with their volcanic environment and may slowly change with time to sulfate-rich salars.

Keywords: Central Andes; Closed basin; Hydrochemistry; Salar; Brine; Salt recycling; Brine evolution

Geochemical History of the Dead Sea by Amitai Katz; Abraham Starinsky (pp. 159-194).

A Southward view of the Dead Sea western coast. The steep western escarpment of the Dead Sea basin, composed mainly of Upper Cretaceous limestone and dolomite, can be seen on the right. Beach terraces left by the shrinking lake run parallel to the shore. The larger part of the area between the present water line and the mountains was still under Dead Sea water just 50–60 years ago. The current fall of the lake’s stand is around 1 m year⁻¹.Three on-shore sinkholes can be seen in the front of the photo, as well as two submerged ones near its lower left corner. These were caused by dissolution of a Holocene salt layer located tens of meters below the surface, resulting in the collapse of the overlying sediments. The retreat of the Dead Sea in recent years was followed by eastward migration of the freshwater–brine interface. This in turn brought diluted groundwater in contact with the subsurface salt layer, triggering its dissolution, and is considered as the culprit of the spreading phenomenon.Many sinkholes contain brine that was left over by the receding Dead Sea and was trapped within the surrounding sediments. Once inside a sinkhole, these brines evolve chemically by evaporation to various degrees. The difference in color between the brine in the onshore sinkholes reflects salinity-related differences in their biology.The evolution of the Dead Sea basin (DSB) brines from their birth in a Pliocene lagoon to their accommodation in the Dead Sea is described and discussed. The history of the brines is divided into two periods, corresponding to the successive depositional environments that prevailed in the DSB, namely a marine lagoon and an inland saline lake. Ancient Mediterranean seawater, supplied into the DSB lagoon through an inland channel from the north, was concentrated by evaporation into the halite field. The resulting Mg-enriched solution dolomitized surrounding, upper Cretaceous limestone, losing most of its Mg²⁺ to the limestone in exchange for Ca²⁺. Cretaceous marine Sr²⁺, concurrently released from the limestone into the brine, lowered its (Pliocene time) ⁸⁷Sr/⁸⁶Sr ratios. Consequently, a Ca-chloridic solution with lowered ⁸⁷Sr/⁸⁶Sr ratios was formed. Frequently changing conditions along the active Dead Sea rift enabled back-flow of the Ca-chloridic brines to the DSB, where they mixed with fresh seawater, unloading into the mixture their limestone-Sr. This process is reflected by the ⁸⁷Sr/⁸⁶Sr ratios (0.7082–0.7087) in the lagoon’s gypsum, dolomite, aragonite, and halite, which is intermediate between that of Pliocene seawater (0.709) and that in the upper Cretaceous limestone (0.7074–0.7077). Disconnection of the lagoon from the ancient Mediterranean brought about its end, and opened the (ongoing) lacustrine chapter of the DSB, without interrupting the reflux of Ca-chloride brine back into the basin. By that time, the chloridic brines processed by the lagoon became locked in a large, almost closed system reservoir in the DSB and vicinity. We propose that a Ca-chloridic lake, the DSB Lake, which was recharged by fresh runoff and by the returning brine, was born and existed in the DSB as of that time. Based on oxygen isotope data, the origin of the freshwater H₂O was in Mediterranean rain. Geological evidence and theoretical calculations constrain the frequent fluctuations of the DSB Lake stand within a minimum of 430–450 and a maximum of 165 mbsl, and its corresponding salinity shifts to within 90 and 340 g l⁻¹, relating these extremes to specific points in time and in the rock sequence. Stratification of the water column, brought about by increase in the inflow/evaporation ratio of the DSB Lake, was a frequent and normal situation, and accounts for the abundant, fine aragonite–detritus lamination in large parts of the DSB section. It is shown that aragonite laminae thicker than 0.1–0.2 mm are not annual deposits but accumulated during several years. Dissolved bicarbonate accumulated in the upper part of the rising lake water column, and was used up for aragonite crystallization upon the subsequent lake decline. Detritus laminae were formed during the respective winter seasons. While remaining Ca-chloridic throughout, the DSB Lake’s composition changed in time as a result of: (a) mixing with fresh waters; (b) removal of the SO₄ ²⁻ and HCO₃ ⁻ imported into the lake in CaCO₃ and CaSO₄ minerals. A mass-balance model, explaining the change in the Mg/Ca ratio in the DSB Lake from its initial value (~0.16) is proposed, and its results are compatible with the composition of the saline springs. It demonstrates that the change in the Mg/Ca ratio in the DSB Lake is mainly caused by removal of Ca from the lake, required to compensate for the Ca < (SO₄ + HCO₃) relationship in the inflow freshwaters. The Mg/Ca ratio in the Dead Sea fluctuated between 4.2 and 4.6 during the last 50 years or so. Insufficient resolution makes it impossible to determine whether the observed changes vary systematically in time. Saline spring waters flow into and mix with the lake, evaporating together, thereby contributing their salts and changing the Dead Sea’s composition. The change is expressed in depletion of Ca, and in the enrichment of the lake in Mg, K, and Br, which do not form independent minerals therein. An attempt to predict the future of the Dead Sea is presented based on the chemical composition of brine in recent sinkholes developing along the Dead Sea coast, as well as on thermodynamic modeling of the Dead Sea brine evolution. The sinkhole brines are compatible with evaporative evolution of Dead Sea water and display salinities up to ~550 g l⁻¹, within the bischofite range. Thermodynamic simulation predicts as well, that under current conditions Dead Sea water may evaporate to a level of not much below 550 mbsl. Simulated evaporation of Dead Sea water to a concentration factor of 50 yielded a 90 m thick column of chloride minerals containing halite, carnallite, bischofite, tachyhydrite, and CaCl₂·4H₂O (by that order).

Keywords: Dead Sea; Ca-chloride brine; Dead Sea basin; Stratification; Lisan; Amora; Zeelim; Samra; Sinkholes; Mount Sedom; Dolomitization; Water–rock interaction; Sr isotopes

Lake Van, Eastern Anatolia, Hydrochemistry and History by Andreas Reimer; Günter Landmann; Stephan Kempe (pp. 195-222).

Saline, 450-m-deep Lake Van (Eastern Anatolia, Turkey) is, with 576 km³, the third largest closed lake on Earth and its largest soda lake. In 1989 and 1990, we investigated the hydrochemistry of the lake’s water column and of the tributary rivers. We also cored the Postglacial sediment column at various water depths. The sediment is varved throughout, allowing precise dating back to ca. 15 ka BP. Furthermore, lake terrace sediments provided a 606-year-long floating chronology of the Glacial high-stand of the lake dating to 21 cal. ka BP. The sediments were investigated for their general mineralogical composition, important geochemical parameters, and pore water chemistry as well. These data allow reconstructing the history of the lake level that has seen several regressions and transgressions since the high-stand at the end of the Last Glacial Maximum. Today, the lake is very alkaline, highly supersaturated with Ca-carbonate and has a salt content of about 22 g kg⁻¹. In summer, the warmer epilimnion is diluted with river water and forms a stable surface layer. Depth of winter mixing differs from year to year but during time of investigation the lake was oxygenated down to its bottom. In general, the lake is characterized by an Na–CO₃–Cl–(SO₄)-chemistry that evolved from the continuous loss of calcium as carbonate and magnesium in the form of Mg-silica-rich mineral phases. The Mg cycle is closely related to that of silica which in turn is governed by the production and dissolution of diatoms as the dominant phytoplankton species in Lake Van. In addition to Ca and Mg, a mass balance approach based on the recent lake chemistry and river influx suggests a fractional loss of potassium, sodium, sulfur, and carbon in comparison to chloride in the compositional history of Lake Van. Within the last 3 ka, minor lake level changes seem to control the frequency of deep water renewal, the depth of stratification, and the redox state of the hypolimnion. Former major regressions are marked by Mg-carbonate occurrences in the otherwise Ca-carbonate dominated sediment record. Pore water data suggest that, subsequent to the major regression culminating at 10.7 ka BP, a brine layer formed in the deep basin that existed for about 7 ka. Final overturn of the lake, triggered by the last major regression starting at about 3.5 ka BP, may partly account for the relative depletion in sulfur and carbon due to rapid loss of accumulated gases. An even stronger desiccation phase is proposed for the time span between about 20 and 15 ka BP following the LGM, during which major salts could have been lost by precipitation of Na-carbonates and Na-sulfates.

Keywords: Lake Van; Soda lake; Holocene; Hydrogeochemistry; Pore water; Lake level history; Paleolimnology

Kara-Bogaz-Gol Bay: Physical and Chemical Evolution by Aleksey N. Kosarev; Andrey G. Kostianoy; Igor S. Zonn (pp. 223-236).

Kara-Bogaz-Gol Bay is a large (around 18,000 km²) and shallow (few meters deep) lagoon located east of the Caspian Sea. Its water surface was several meters to several dozens cm lower than in the Caspian Sea, so water flows from the Caspian Sea through a narrow strait into the bay, where it evaporates. Kara-Bogaz-Gol Bay is one of the saltiest bodies of water in the world; its water salinity amounts to 270–300 g/l. Different kinds of salts available in this natural evaporative basin has been used commercially since at least the 1920s. In March 1980, in order to decelerate a continuous fall of the Caspian Sea level, which in 1977 was the lowest over the last 400 years (−29 m), the Kara-Bogaz-Gol Strait was dammed. In response to this human intervention, the bay had already dried up completely by November 1983. In 1992, the dam was destroyed, and Kara-Bogaz-Gol Bay had been filling up with the Caspian Sea water at a rate of about 1.7 m/year up to 1996 as observed by the TOPEX/Poseidon satellite altimetry mission. Since then, Kara-Bogaz-Gol Bay level evolution with characteristic seasonal and interannual oscillations has been similar to that of the Caspian Sea. Physical and chemical evolution of the bay in the twentieth and twenty-first centuries is traced in detail in the paper.

Keywords: Kara-Bogaz-Gol Bay; Caspian Sea; Mineral salts; Sea level; Salinity

Role of Subsurface Brines in Salt Balance: The Case Study of the Caspian Sea and Kara Bogaz Bay by Norbert Clauer; Marie-Claire Pierret; Sam Chaudhuri (pp. 237-261).

The water level of the Caspian Sea fluctuated significantly during recent history, without consensus for the cause. The varied chemistry of the Caspian, Kara Bogaz and sediment a interstitial waters provides a further insight. Element concentrations and ⁸⁷Sr/⁸⁶Sr ratios of the interstitial waters were compared to those of Caspian and Kara Bogaz open waters, and of acid-leached extractable components. The ⁸⁷Sr/⁸⁶Sr ratios of the interstitial waters are explained by addition of subterranean waters similar to nearby spring waters. These subterranean waters yield chemical characteristics such as a Cl/SO₄, ⁸⁷Sr/⁸⁶Sr, Ca/Sr and K/Rb ratios of respectively 80, 0.7086, 250 and 1,800. However, their addition does not explain the large difference in the K/Rb ratio of the Caspian and Kara Bogaz waters, respectively at 7,630 and 17,550, which implies also a leaching of salt deposits by the upward migrating subterranean waters. The sediments of the southern Caspian basin, with low Na, Cl and SO₄ in their interstitial waters, deposited apparently in an anoxic environment. The related chemical changes in the waters are also indicative of a recent change in the hydrologic regime, possibly induced by a changing morphology of the drainage basin.

Keywords: Caspian Sea; Kara Bogaz; Interstitial and subterranean waters; Water chemistry; ⁸⁷Sr/⁸⁶Sr ratios; Salt balance

Ongoing Changes of Ionic Composition and Dissolved Gases in the Aral Sea by Peter O. Zavialov; Anatoliy A. Ni; Timofei V. Kudyshkin; Durdibay P. Ishniyazov; Irina G. Tomashevskaya; Dilia Mukhamedzhanova (pp. 263-275).

Starting from 1961, the Aral Sea, a major saline lake in Central Asia, has been continuously shrinking because of deficiency in its water budget. Accordingly, the salinity of the once brackish lake increased by a factor of magnitude. During the desiccation, the salt composition of the Aral Sea has been subject to continuous changes because of chemical precipitation accompanying the salinity buildup. This paper provides a summary of these changes based on water samples collected from the so-called Large Aral Sea during the field surveys of 2002–2007. Once fully ventilated, the lake developed anoxic conditions and H₂S contamination is frequently observed in the bottom layers. However, hydrogen sulfide is a variable rather than a permanent feature of the present Aral Sea. Because of the precipitation of calcium carbonate, gypsum, and, possibly, mirabilite, which successively occurred as the salinity increased, the relative content of SO₄ ⁻ and Ca²⁺ ions decreased. Accordingly, compared with the pre-desiccation period before 1960, the sulfate-to-chloride mass ratio decreased by 10–30%, while the relative content of calcium decreased almost 7-fold. The depletion in calcium is more pronounced in the shallow eastern part of the lake, where salinity is much higher. However, the reduction of the sulfate-to-chloride ratio in the eastern basin is smaller than that for the western basin of the Aral Sea. Hypothetically, this could be explained through precipitation of halite already taking place in the eastern basin, but not yet in the western basin. Vertical profiles of the ionic content in the relatively deep western part of the lake reveal a decrease of calcium content and relative increase of sulfate ion content toward the bottom, which is consistent with the previously published concept that the bottom layers of the western trench contain a significant admixture of the water advected from the eastern basin.

Keywords: Aral Sea; Dissolved gases; Ionic composition

Investigations on Aral Sea Regressions from Mirabilite Deposits and Remote Sensing by Jean-François Crétaux; Rene Létolle; Stephane Calmant (pp. 277-291).

Remote sensing techniques including radar (Topex/Poseidon, Jason-1 and Envisat) and laser altimetry (Icesat), and moderate resolution spectro-radiometer (MODIS) images, are used to estimated current level and surface extent time variations of the Aral Sea. During the Holocene several phases of regression occurred, leading to desiccation of the Aral Sea. During the last 50 years, Aral Sea has drastically shrunk due to intense use of river’s water for irrigation purposes. It is currently separated into four distinct water bodies, namely, the Small Aral in the North, the Tchebas Bay in the North West, and the South West and the South East basins. The Kulandy strait connected the SW and SE basins until very recent times. These basins are now almost separated and salinity becomes very high (140–180 g/l) in the Eastern part. Rubanov discovered past deposits of mirabilite in the years 1970–1980. We investigate the significance of these deposits in the light of current evolution of the four water bodies that constitute the heritage of Aral Sea contemporary desiccation. Using remote sensing techniques, we have attempted to calculate the water balance of south Aral Sea during the last 3 years. We conclude in strong probability that the Kulandy strait carries water most of the time from the Eastern Basin to the Western Basin. We have demonstrated that it should have been the same process in the past to explain the Mirabilite deposit, but unfortunately, due to recent artificial water monitoring of the Aral Sea (dam in the Berg’s strait, new reservoirs in the Amu Darya’s delta), it is impossible to make definitive conclusion from actual Aral Sea water balance.

Keywords: Mirabilite; Aral Sea; Altimetry; Regressions

Hydrochemistry of Salt Lakes of the Qinghai-Tibet Plateau, China by Mianping Zheng; Xifang Liu (pp. 293-320).

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 Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻ SO₄ ²⁻, CO₃ ²⁻, and HCO₃ ⁻. In this paper, the Kurnakov-Valyashko 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 = Na₂CO₃ + NaHCO₃/total salt × 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 (L₂CO₃) 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-schoenite-halite, 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-mentioned salt lake mineral assemblages of various types on the plateau have features of cold-phase assemblages. Mirabilite and its associated cold-phase saline minerals are important indicators for the study of paleoclimate changes of the plateau. A total of 59 elements have been detected in lake waters of the plateau now, of which the concentrations of Na, K, Mg, Ca, and Cl, and SO₄ ²⁻, CO₃ ²⁻, and HCO₃ ⁻ ions are highest, but, compared with the hydrochemical compositions of other salt lake regions, the plateau salt lakes, especially those in the southern Qiangtang carbonate type subzone (I₂), contain high concentrations of Li, B, K, Cs, and Rb, and there are also As, U, Th, Br, Sr, and Nd positive anomalies in some lakes. In the plateau lake waters, B is intimately associated with Li, Cs, K and Rb and its concentration shows a general positive correlation with increasing salinity of the lake waters. The highest positive anomalies of B, Li, Cs, and K center on the Ngangla Ringco Lake area in the western segment of the southern Qiangtang carbonate type subzone (I₂) and coincide with Miocene volcanic-sedimentary rocks and high-value areas of B, Li, and Cs of the plateau. This strongly demonstrates that special elements such as B, Li, and Cs on the plateau were related to deep sources. Based on recent voluminous geophysical study and geochemical study of volcanic rocks, their origin had close genetic relation to anatectic magmatism resulting from India–Eurasia continent–continent collision, and B–Li (-Ce) salt lakes in the Cordillera Plateau of South America just originated on active continental margins, both of which indicate that global specific tectonically active belts are the main cause for the high abundances of B, Li, and Cs (K and Rb) in natural water and mineralization of these elements.

Keywords: Qinghai-Tibet Plateau; Salt lake; Zoning of hydrochemical types; Salt lake mineral assemblage; Boron, lithium, potassium, cesium, rubidium; Material source

The Saline Lakes of the McMurdo Dry Valleys, Antarctica by William J. Green; W. Berry Lyons (pp. 321-348).

The McMurdo Dry Valleys of Antarctica are among a rare group of ice-free regions lying along the coast of an otherwise ice-burdened continent. For Antarctica, these are highly atypical regions of exposed rock and barren soils. Within their 4,000 km² expanse, the valleys contain a number of permanently ice-covered, closed-basin lakes, which range from freshwater to highly saline environments. This paper examines the physical structure, geochemistry, nutrient and trace metal dynamics, biology, and hydrologic history of saline Lake Bonney (both east and west lobes), Fryxell, Vanda, and Joyce and provides an update to recently published volumes on these pristine systems.

Keywords: Saline lakes; McMurdo Dry Valleys; Chemical evolution; Metals; Biogeochemistry

Sections

Personal tools

Aquatic Geochemistry (v.15, #1-2)

Sections

Personal tools

Local resources

Aquatic Geochemistry (v.15, #1-2)