Shallow Saline Lake Research Articles

Lateral and temporal constraints on the depositional history of the Bonneville Salt Flats, Utah, USA

AbstractThe depositional history of the Bonneville Salt Flats, a perennial saline pan in Utah's Bonneville basin, has poor temporal constraints, and the climatic and geomorphic conditions that led to saline pan formation there are poorly understood. We explore the late Pleistocene to Holocene depositional record of Bonneville Salt Flats cores. Our data challenge the assumption that the saline pan formed from the desiccation of Lake Bonneville, the largest late Pleistocene lake in the Great Basin, which covered this area from 30 to 13 cal ka BP. We test two hypotheses: whether climatic transitions from (1) wet to arid or (2) arid to wet led to saline pan deposition. We describe the depositional record with radiocarbon dating, sedimentological structures, mineralogy, diatom, ostracode, and portable X-ray fluorescence spectrometer measurements. Gypsum and carbonate strontium isotope ratio measurements reflect changes in water sources. Three shallow saline lake to desiccation cycles occurred from >45 and >28 cal ka BP. Deflation removed Lake Bonneville sediments between 13 and 8.3 cal ka BP. Gypsum deposition spanned 8.3 to 5.4 cal ka BP, while the oldest halite interval formed from 5.4 to 3.5 cal ka BP during a wetter period. These findings offer valuable insights for sedimentologists, archaeologists, geomorphologists, and land managers.

Gypsum lakes, sandflats and soils revealed from the Triassic Red Peak Formation of the Chugwater Group, north‐central Wyoming

AbstractBedded gypsum is relatively common in bedded evaporites associated with red bed siliciclastics of Permo‐Triassic Pangea. However, little attention has been paid to the textures of ancient gypsum, which can be used to refine interpretations of depositional environment and diagenetic history. This project describes the textures of bedded gypsum from an outcrop of the Triassic Red Peak Formation (Chugwater Group) near Greybull, Wyoming. Fieldwork, petrography and X‐ray diffraction reveal three distinct lithologies of bedded gypsum: bottom‐growth gypsum, laminated gypsum and clastic gypsum. Bottom‐growth gypsum precipitated at the bottom of shallow saline surface water bodies. Laminated gypsum probably formed in shallow saline lakes and mudflats. Clastic gypsum units are composed of aeolian‐reworked bottom‐growth gypsum crystals deposited in sandflats. Red siliciclastic mudstones are characterised by their massive nature and abundant blocky peds. Detailed study of this outcrop of the Red Peak Formation shows that it formed in shallow saline lakes and associated mudflats, sandflats and desert soils.

Roman water management impacted the hydrological functioning of wetlands during drought periods

During the Roman domain of the Iberian Peninsula (from 201 BCE to 460 CE) water management infrastructures were built to satisfy high water demand. However, whether the Roman activities affected the hydrological balance of Iberian wetlands remains unclear. Here, we investigate the paleo-hydrology of Lake Zóñar (southern Iberia) by using the stable isotopes (16O, 17O, 18O, 1H and 2H) of its gypsum (CaSO4·2H2O) sediments and reconstruct the isotopic composition of the lake water during Roman times. A period of recurrent lake low stand occurred between 2120 and 1890 cal. yr BP (ca. 170 BCE to 60 CE), coinciding with a relatively dry climate stage recorded by most regional paleoclimate archives. The stable isotopes and hydrochemistry of the lake water during gypsum precipitation are consistent with a shallow saline lake that evaporated under relative humidity ~ 10% lower than the present annual mean and at least 20% less rainfall amount. Our analytical and archeological findings support lake level lowering during the Roman period was probably caused by combined arid climate conditions and diversion of the inlets feeding the lake. Spring capturing was likely necessary to satisfy the high water demand of nearby Roman settlements, in the framework of a period of persistent droughts.

Colonization-persistence trade-offs in natural bacterial communities.

Fitness equalizing mechanisms, such as trade-offs, are recognized as one of the main factors promoting species coexistence in community ecology. However, they have rarely been explored in microbial communities. Although microbial communities are highly diverse, the coexistence of their multiple taxa is largely attributed to niche differences and high dispersal rates, following the principle 'everything is everywhere, but the environment selects'. We use a dynamical stochastic model based on the theory of island biogeography to study highly diverse bacterial communities over time across three different systems (soils, alpine lakes and shallow saline lakes). Assuming fitness equalization mechanisms, here we newly analytically derive colonization-persistence trade-offs, and report a signal of such trade-offs in natural bacterial communities. Moreover, we show that different subsets of species in the community drive this trade-off. Rare taxa, which are occasional and more likely to follow independent colonization/extinction dynamics, drive this trade-off in the aquatic communities, while the core sub-community did it in the soils. We conclude that equalizing mechanisms may be more important than previously recognized in bacterial communities. Our work also emphasizes the fundamental value of dynamical models for understanding temporal patterns and processes in highly diverse communities.

Fine-grained carbonate formation and organic matter enrichment in an Eocene saline rift lake (Qianjiang Depression): Constraints from depositional environment and material source

Carbonate-rich fine-grained rocks in saline lakes have become potential targets for shale oil and gas exploration. However, few studies have investigated the processes of carbonate formation and organic matter enrichment in hypersaline environments. The Qianjiang Depression is a hypersaline rift lake basin that contains carbonate-rich fine-grained rocks in the inter-salt strata of the Qianjiang Formation. In this study, sedimentological observations and multiple geochemical analyses were conducted on the inter-salt strata in the sixth and eighteenth rhythmites of the Qianjiang 4 Member. The results showed that the middle inter-salt stratum in the sixth rhythmite is rich in dolomite, calcite, and organic matter, whereas the inter-salt stratum in the eighteenth rhythmite is rich in dolomite and sulfate minerals and low in organic matter. Comparisons among multiple redox parameters revealed that the middle inter-salt stratum in the sixth rhythmite was formed in a deep saline lake, while the inter-salt stratum in the eighteenth rhythmite was formed in a shallow saline lake. Further, sedimentary observations and analyses of δ34S and trace and rare-earth elements revealed that the inter-salt stratum in the sixth rhythmite contained a significant amount of volcanic ash, whereas that in the eighteenth rhythmite was influenced by hot brine derived from older strata. Therefore, the differing environments and material inputs notably affected the carbonate crystallization and organic matter enrichment in these strata. This study suggests that the input of volcanic materials is conducive to improving biological productivity in saline lakes, and anoxic conditions with moderate salinity are conducive to the preservation of organic matter. These findings provide theoretical guidance for future self-sourced inter-salt shale oil reservoir explorations.

Sediments of Lake Malye Chany as a Late Holocene paleoecological archive in the south of West Siberia (Russia)

Abstract. The paper presents the first results of multiproxy study of the sediment core from Lake Malye Chany. This lake is a part of the biggest drainless lake in Russian Lake Chany. The Kargat and Chulym Rivers flow into Malye Chany. The lake locates in the forest-steppe near the southern border of taiga zone which makes it a promising object for reconstructions of the vegetation shifts and other ecological changes of the past periods. The sediment core was investigated by sedimentological, pollen, chironomid, diatom, ostracod analyses. Based on pollen and chironomid data were maid quantitative reconstructins of climate, vegetation cover and biodiversity. According to radiocarbon dates the upper 200 cm of the core covers the last ca. 3900 years. It was established that reconstructed time boundaries of climate, vegetation and ecological changes coincide according to various reconstruction approaches. At the beginning of its existence, Lake Malye Chany was a shallow saline lake with warm water; only after 2.4 thousand years BP the water level rose and the lake became fresh and the water colder. Then the water level and salinity changed, and only 1 thousand years BP the lake became deep again. The last 200 years recorded a slight warming of the water. Landscapes developed from very dry steppe to modern forest-steppe, about 2 thousand years ago there was a short-term cooling and spread of taiga elements. Last 200-300 years, there has been a steppification.

Geochemical indication of the Holocene climatic changes in sediments of Bolshoi Bagan Lake, Southern West Siberia

Abstract. Our study of the Holocene sediments of shallow saline Lake Bolshoy Bagan located revealed the following stages of the lake evolution: (I) Appearance and maturing of the lake 9.1 5.8 ka BP; (II) rise in water level 5.8 2.3 ka BP; and (III) shallowed lake 2.3 0 ka BP.

Climate signals in the Holocene bottom sediments of shallow saline lakes of the Southwestern Siberia

Abstract. We present the results of the study of the Holocene sediments from two shal low lakes of different salinity located in the East Baraba lowland (Southwestern Siberia). The research methods: X-ray diffractometry (XRD), IR spectroscopy, laser particle size analysis, AMS dating, etc. By the mathematical modeling of complex XRD patterns Mg-calcites with different Mg contents, excess-Ca dolomite and aragonite have been established in the assemblages of carbonate minerals. Based on studies of mineralogical-crystallochemical features and quantitative ratios of Ca-Mg carbonates the evolution stages of lakes corresponding to the regional cycles of aridization/humidization were identified and the correlations with global climatic events were carried out. The obtained results is an important source of new information about the Holocene climate in the Southwestern Siberia.

Revisiting bathymetry dynamics in Lake Urmia using extensive field data and high-resolution satellite imagery

Bathymetric mapping for an accurate estimation of stored water volume in drying lakes is a key information for an effective monitoring of their recession or restoration status. Extraction of bathymetry in shallow saline lakes using remote sensing techniques has always been challenging due to the complex influences imposed by the physical properties of substrate and the spatial variability of salinity. In this study, we developed a machine learning-based model to quantify the implicit, non-linear relationship between water depth and surface reflectance by leveraging extensive in-situ data and high-resolution satellite imagery. We trained and tested the learning model in the hyper-saline Lake Urmia (LU), which faced catastrophic drying over the past two decades. To this end, we used Landsat-8 imagery and 32,984 hydrography data points surveyed by the Urmia Lake Restoration Program (ULRP) from 2017 to 2020 during six stages. To enhance the model accuracy, we tuned the model inputs by optimizing the spectral information and clustering in-situ data from stages with similar meteorological conditions into three classes. The results demonstrated the high accuracy of the developed intelligent model as evidenced by R2 = 0.8 ∼ 0.9 and RMSE = 7.8 ∼ 17.9 cm for the three models. We found that the average water depth in the LU was increased from 0.43 m in September 2018 to 2.00 m in May 2020. In particular, the lake water volume in May 2020 was 3.6 times greater than that in February 2019, which marks a remarkable shift in the LU restoration. Dynamic bathymetric maps also witnessed considerable salt dissolution taking place across the lake during this period. Finally, we extracted the LU level-area relationship by processing 172 Landsat images between 1984 and 2020, which was validated against the field data surveyed along the lake water boundary in 2019. The results indicated that the level-area relationship follows a dual linear relationship separated at the water level of 1271.31 m.

Paleolimnological record of the Pampean plains (Argentina) as a natural archive of South American hydroclimatic variability since the LGM to the Current Warm Period

Laguna Mar Chiquita (LMC, 30°54′S – 62°51′W) is a highly variable and shallow saline lake, located in the Pampean Plains of Argentina. The paleolimnological record of LMC contains information on the environmental variability that occurred in a large area of Southern South America since the Last Glacial Maximum (LGM) until the present. As inferred from the diatom assemblages, sedimentary features and geochemical proxies, prolonged intervals of high and lowstands have caused variations in water salinity, trophic state and sedimentary processes. This is the first paleolimnological reconstruction covering the hydroclimatic variability that occurred over the last 25,000 cal yr BP in the Argentinean Pampean region. Results are in accordance with well-known global climatic phases. The Late Pleistocene record is characterized by a scenario dominated by lowstands, hypersaline, and oligotrophic lake conditions. Radiocarbon ages (25,000–19,000 cal yr BP) indicate that the onset of the record is coeval with the LGM. Later, a progressive lake water level increase was registered at ⁓17,000 cal yr BP, which can be assigned to the Heinrich Stadial 1. A shift toward comparatively drier conditions identified in the record between ⁓14,700 and 13,000 cal yr BP can be chronologically related to the Antarctic Cold Reversal. The transition from the Late Pleistocene to the Holocene (13,500–10,500 cal yr BP) is recorded by highstand phases while the Early Holocene record is characterized by high to intermediate water levels. The hydrological reconstruction corresponding to the Mid-Holocene is characterized by alternating phases of high/lowstands. The onset of the Late Holocene record is marked by the development of dry conditions and thus lowstand phases, while around 1300 cal yr BP a distinct water lake level increase is recognized. This humid phase, ascribed to the Medieval Climatic Anomaly, is followed by the record of lowstands between 500 and 1000 cal yr BP, being coeval with the Little Ice Age. The uppermost part of the record of LMC encompasses the Current Warm Period, showing a marked shift towards high lake water level conditions. The hydrological variability registered in the paleolimnological record, highlights the importance of Laguna Mar Chiquita as an outstanding paleoclimate sensor of hydroclimatic variations for a large area of South Eastern South America.

Geomorphological control of habitat distribution in an intermittent shallow saline lake, Gallocanta Lake, NE Spain

The aim of the present study consists on the establishment of any relationship or interaction between geomorphological processes and vegetation/habitat distribution in an area with strong environmental gradients: an active saline lake in NE Spain. The resulting maps of the major geoforms and CORINE habitats within the lacustrine area were overlain to determine any significant relationships, taking into account the elevation derived from Lidar data. Whereas the geoforms resulted to have a roughly concentric distribution, the habitats appeared to be spread across different areas, and flooding frequency seemed not to be a determining factor in their altitudinal distribution. The correspondence matrix for geoforms and habitats underlined the coincidence between presently active morphodynamic units, flooding/salinity, and habitats typical of saline environments. Geomorphological units associated with the presently active shoreline dynamics host the habitats more typically related to frequent flooding and high salinity levels. The delay between geomorphological dynamics and vegetation changes, together with the opportunistic character of vegetation, promote the coexistence of different geomorphological processes and a great variety of plant communities and habitats. As a major conclusion, the present study provides a method through which a standard procedure may be set up to further determine the interaction between geomorphological processes and vegetation distribution, very useful for understanding vegetation patterns and conservation biodiversity, and the planning and managing of Natura 2000 sites.

Long-term data on plankton communities in Torey lakes, a shallow saline lakes, Transbaikalia, Russia

This study aims to investigate dynamics of environmental and plankton parameters during the drying and initial filling phases of Torey lakes. These lakes located in the South-East Transbaikalia are shallow saline fluctuating lakes. We conducted our studies during different water level phases of the hydrological cycle, including three periods for Zun-Torey Lake: high (1999 and 2003), intermediate (2007, 2011) and low (2014 and 2016) lake levels and two periods for Barun-Torey: high water level (1999 and 2003) and the initial filling phase (2014, 2016, 2018). Fluctuations in water level and environmental conditions (TDS, pH, dissolved oxygen content, water temperature) changes due to dilution and concentration have influence on phyto- and zooplankton structure. Fluctuations of plankton communities are different for each lake and conform the phases of the hydrological cycle. We have identified four stages in changes of plankton community for Zun-Torey Lake as the deeper and slowly drying, and three stages for Barun-Torey Lake as a shallower and rapidly drying.

Depositional environments in an arid, closed basin and their implications for oil and gas exploration: The lower Permian Fengcheng Formation in the Junggar Basin, China

The Fengcheng Formation is a nonmarine, carbonate-dominated succession that formed under arid climatic conditions in a hydrologically closed basin. Two transects and two seismic profiles were examined, the characteristics and environmental significance of different lithofacies were studied, and a model of depositional environment divisions was proposed. The sedimentary model involved an alkaline lake in which the depositional environments consisted of a shallow saline lake margin, slope, saline lake center, and steep lake margin from northeast to southwest. The perennial central salty lake was located in the southwestern part of the study area, whereas there were widespread, low-gradient lake margins in the northeast, east, southeast, and southern parts of the study area. Lake-level fluctuations had a major influence on the shallow saline lake system and complicated the depositional environments in these areas. The deposits are derived from bedrock reworking, volcanic eruptions, and authigenic minerals that precipitated from brine during the hypersaline phase. Fine-grained terrigenous clastic sediments, volcanic ashes and dusts, and authigenic minerals mixed in the depocenter (concentration center of the brine pool), which was covered by high-salinity brines, and the depositional environment was anoxic as a result of salinity-based brine stratification. A thick sodium carbonate succession occurred in the depocenter of the ancient Mahu lake, where bedded sodium carbonate alternated with fine-grained, organic-rich tuff or tuffaceous hydrocarbon source rocks. Microorganisms bloomed in the alkaline, high-salinity brine, and the organic matter was well preserved, which is similar to those modern alkaline saline lakes in eastern Africa and western North America. Thus, the Permian Fengcheng Formation contains source rocks that formed in an alkaline saline lake.

Groundwater recharge and hydrodynamics of complex volcanic aquifers with a shallow saline lake: Laguna Tuyajto, Andean Cordillera of northern Chile

Estimating groundwater recharge in arid regions with seasonal snow cover, as in the Andean Altiplano of northern Chile, is important for sustainable development policies and the effective management of scarce resources in a high water demanding zone, as fragile ecosystems depends on a stable water contribution. This research aims to evaluate and quantify rainfall and snowfall contribution to aquifer recharge while assessing the factors that control the hydrodynamics in such areas, based in the knowledge of the better documented Tuyajto Lake in the Tuyajto catchment/basin. The modeling framework involves an energy balance of the snow cover, a soil water balance and a groundwater flow and chloride transport model. The basin average annual recharge is about 23% of average precipitation. Snowmelt contribution to recharge is important at altitudes above 4700 m a.s.l. during September, while rainfall is more important in February and March, during short intense precipitation events. The hydraulic conductivity of ignimbrites and other volcanic formations are the most important hydrogeological parameters controlling lake level and spring flow rates, while albedo and snowpack surface roughness length on the energy balance causes the greatest variation of lake level. Evaporation is the process controlling the variability of the lake level, as aquifer contribution remains relatively constant and springs flow variability is not enough to cause the observed variations, except during November. Possible buried salts deposits on the eastern edges of Pampa Colorada and Tuyajto Lake, together with volcanic HCl contribution, justify the high measured groundwater chloride concentrations. A recharge 2–3 higher than the current one is necessary to justify a lake level 40 m above its modern value during the Last Glacial period, giving insight into past hydrological changes in the basin due to climate variability. The knowledge gained can be applied to other high altitude volcanic basins with seasonal snow cover.

Late Quaternary aeolian and fluvial-aeolian deposits from southwestern Pampas of Argentina, southern South America

The central region of Argentina, southern South America, is characterized by an extensive Quaternary aeolian record. In this context, three locations from the southwestern Pampas, an Andean foreland region bearing a rich fossil mammal record that contributed to the South America biostratigraphic scheme, were selected to carry out a comprehensive sedimentological analysis of the late Quaternary deposits. The case studies are located at the Transverse Valleys of La Pampa province (Chapalcó, Quehué and Utracán-Argentino valleys), and exhibit a high resolution of the late Quaternary in comparison with others areas of the southwestern Pampas. The Toay locality (~36° 41′S, 64° 24′W) records aeolian-dominant activity since the end of the Late Pleistocene (~30 ka) onwards, soil formation at some point during the Holocene and early–mid 20th century reactivation of aeolian process. The Arroyo Quehué locality (~37°04′S, 64°42′W) presents a Late Pleistocene-Holocene succession mostly related to an ephemeral endorheic fluvial system, with an interval of relative surface stabilization and aeolian aggradation during the Late Holocene. The Utracán locality (~37°17′S, 64°35′W) exhibits a prevailing aeolian and fluvial-aeolian interaction succession developed in the mid-to Late Holocene in a sand-mud flat environment of a shallow saline lake. The three studied cases are representative of aeolian aggradation in association with ephemeral fluvial, shallow lake and pedogenic processes in a currently subhumid-dry region. Numerical ages indicate sedimentation during the last ~30 kyr. They allow constraining and evaluating the paleoenvironmental conditions in this inland region of southern South America, and provide age constraints for the regional databases of paleoclimatic proxies. The results are in agreement with other late Quaternary paleoclimatic-paleoenvironmental archives of central Argentina and show a fragile aeolian landscape that is susceptible to deterioration under extreme conditions, including both aeolian reactivation during dry phases and erosion of sandy-silty sediments during wet phases.

Acid-saline-lake Systems of the Triassic Mercia Mudstone Group, County Antrim, Northern Ireland

Abstract The Triassic Mercia Mudstone Group of County Antrim, Northern Ireland, is dominated by red beds and evaporites. After only limited study, both marine and continental environments have been proposed previously. Here, we describe these rocks for the first time from core and petrographic observations to interpret depositional environments and conditions, such as water depth, salinity, and aridity. Bedded halite, bedded gypsum, displacive halite, and red siliciclastic mudstone lithologies comprise most (∼ 80%) of the 591.6-m-thick Mercia Mudstone Group in the Gaelectric Carnduff-2 core. Bedded halite consists of chevron and cornet crystals, indicating bottom-growth from shallow surface brines. Bedded-gypsum lithology is composed of halite-replaced pseudomorphs after swallowtail, bottom-growth gypsum crystals. Both bedded halite and bedded gypsum contain dissolution features and are commonly overlain by mud drapes. Bedded-halite and bedded-gypsum lithologies are interpreted to have formed in shallow saline lakes influenced by flooding and evapoconcentration. The displacive-halite lithology is composed of sub-cubic halite crystals, randomly oriented in mudstone, and represents deposition in a saline mudflat. Some mudstones contain ripple cross-lamination, dewatering structures, mudcracks, and rip-up clasts, suggesting shallow surface water and desiccation. Other mudstones are massive (structureless) and may have been deposited by wind. Both of these mudstone units were likely deposited in dry mudflats. Other red mudstones contain soil slickensides, blocky peds, and circumgranular cracks and are interpreted as paleosols. Our observations indicate that the Triassic Mercia Mudstone Group was formed by shallow perennial saline lakes and associated continental environments in an arid climate. Furthermore, lack of carbonates, lack of fossils, and paucity of organic matter suggest acid saline lakes and groundwaters. The Triassic Mercia Mudstone Group is similar to some other Pangean red beds and evaporites. Therefore, we hypothesize that the supercontinent was an arid barren landscape hosting acid-saline lakes.

Late Paleogene saline lake evolution of the Ningnan Basin and its response to the regional paleoclimate and uplift of the Tibetan Plateau: Evidence from sedimentary strata, and S and Sr isotopes

A saline lake developed in the Ningnan Basin during the sedimentation of the Qingshuiying Formation in the Late Paleogene. In order to research the evolutionary characteristics of the saline lake and its response effect to the regional paleoclimate and uplift of the Tibetan Plateau in the Late Paleogene, the Hejiakouzi section of Qingshuiying Formation in the north of the Ningnan Basin was selected. The features of the strata, gypsum petrology, and S and Sr isotopes of synsedimentary gypsum were studied. Furthermore, the relationship of the evolution of the saline lake to the regional paleoclimate and the uplift of the Tibetan Plateau are discussed. The results showed that the lithology of Qingshuiying Formation was mainly celadon‐aubergine mudstone and gypsum. S and Sr isotopic values of synsedimentary gypsum were 8.2–12.3‰ and 0.7105–0.7113, respectively. The sedimentary environment of Qingshuiying Formation was generally a weak continental saline lake, which can be further divided into 4 kinds of sedimentary environment, namely deep saline lake, semi‐deep saline lake, shallow saline lake, and brackish lake. At 45–40 Ma, the first uplift of the Tibetan Plateau occurred with a humid climate, and a brackish lake was mainly germinated. At 40–30 Ma, the climate was dry and hot, and deep and semi‐deep saline lakes mainly developed. At 30–27 Ma, the climate became dry and cold, and a shallow saline lake mainly developed. At 27–23 Ma, the second uplift of the Tibetan Plateau occurred, the climate became humid and cold due to the East Asian summer monsoon, and a brackish lake mainly developed, and the evolution of saline lake was completed by this time.

Chemical composition and trophic state of shallow saline steppe lakes in central Asia (North Kazakhstan).

The purpose of this study was to identify the prevailing chemical composition and trophic state of the shallow saline steppe lakes of North Kazakhstan along a wide size range (<1-454km2) and salinity gradient (2-322gL-1) on a large spatial scale (1000km), taking into account the potential effects of human disturbances. Water depth, Secchi disk transparency, temperature, pH, electric conductivity, major ions, total dissolved solids, total organic carbon, total nitrogen and phosphorus, nitrate, soluble reactive phosphorus, and chlorophyll a were measured. The equivalent percentage of major ions, Spearman rank correlation, multivariate analyses, equilibrium state of lakes, and spatial GIS autocorrelation were calculated. The impact of human disturbances (settlements, farms, and mines) on total organic carbon, nitrogen, phosphorus, and chlorophyll a were tested by Kruskal-Wallis ANOVA. The most common combinations of dominant ions were Na-Cl>SO4 and Na-Cl (n=16; 64%); the Ca, Mg, HCO3, and SO4 ions precipitate with increasing salinity (2-322gL-1); and ion composition shifts from Na>Mg-Cl>SO4 to Na-Cl. The most of the chemical variables positively, but chlorophyll a negatively, correlated with total dissolved solids, and the total phosphorus had no significant correlation with any variables. The trophic state of these lakes in most cases exceeded the hypertrophic level. The increase in salinity causes change in chemical composition and effects on the phytoplankton development independently from the size of water surface, and the human disturbances had negligible effect on the trophic state of shallow saline lakes in this region of Kazakhstan.

Carbonate sedimentation in shallow saline lakes of Western Transbaikalia: The response to Holocene climate changes

New research results are presented on the processes of carbonate sedimentation in shallow saline lakes of Western Transbaikalia by the example of the Holocene bottom sediments of Sul’fatnoe Lake (the Selenga Dauria). The techniques of X-ray diffractometry (XRD), IR spectroscopy, laser granulometry, and isotope and elemental analyses were used. By means of decomposition the XRD profiles using the Pearson VII function, the carbonate phases were identified and their quantitative ratios were determined. The evolution of the lake basin caused by climate changes in the Holocene was reconstructed by comparing the carbonate record to the concentrations determined for the 18O and 13C stable isotopes and to lithological, geochemical, and palynological data in the dated sedimentary section.

Impact of water input on plankton temporal dynamics from a managed shallow saline lake

La Salada is a shallow saline lake located in the SW of the Pampas subject to significant water management, so the primary objective was to assess whether the water input and physicochemical parameters have an impact on the plankton assemblages over a two year period (2013–dry and 2014–wet). The plankton community structure and physicochemical variables showed substantial changes over the study period. La Salada hosted a plankton community characterized by low diversity and small sized organisms. The nanoplanktonic fraction organisms (2–20 μm) dominate the phytoplankton community. Ochromonas sp. showed the maximum abundance throughout the whole study period. The zooplankton community was dominated by rotifers, with a lack of cladocerans. Halotolerant species, e.g. the rotifer Brachionus plicatilis and the cyclopod Apocyclops sp. were the main species. The seasonal temperature and conductivity dynamics influence the plankton abundance dynamics in La Salada. The increment of nutrients and decrease of conductivity caused by the water input led to an increase in plankton biomass and shaped its composition. These findings emphasize that interactions between plankton, salinity, and nutrients are sensitive to the water input and they improve the understanding of the impact of adequate management decisions.