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A 25 m long sediment core from hypersaline Urmia Lake (north‐west Iran) was studied for the Late Quaternary depositional history and palaeoclimate variations using the abundance and compositional characteristics of Artemia faecal pellets. Sediment analysis is supported by scanning electron microscopy – energy dispersive X‐ray spectroscopy, organic and inorganic carbon content measurements, and stable isotopes (δ13C and δ18O) from faecal pellet carbonates. The imprecise chronology of the core back to 50 kyr bp is supported by ten radiocarbon ages from faecal pellets and bulk sediments. The palaeoenvironmental record is subdivided into four periods: (i) During much of Marine Isotope Stage 3, a period of lake level lowering is characterized by a decreasing amount of faecal pellets, and an increasing amount of coated grains, sulphate minerals and reworked shell fragments. (ii) During late Marine Isotope Stage 3 and early Marine Isotope Stage 2 a lake level lowstand and a lake floor exposure is interpreted based on the relatively low abundance of pellets, which are multicoloured and appear together with volcanic lithics and rounded sulphate minerals. (iii) During late Marine Isotope Stage 2 the record is devoid of pellets but dominated by large sulphate crystals suggesting a prolonged low lake level. (iv) During Marine Isotope Stage 1 a relative lake level highstand is rapidly established with sediments that are highly abundant in fresh pellets. The modern lake level lowstand is represented by a salt crust. The δ13C and δ18O records measured from faecal pellet carbonates suggest a link with the precipitation versus evaporation balance in the lake over time. From bottom to top the linear trend towards more negative delta values illustrates the increasing amount of precipitation arriving at the lake from the Late Pleistocene to the Holocene. Two prominent isotope minima during the Late Pleistocene and one prominent minimum in the early Holocene mark relative high lake levels, which can also be linked to Lake Van in Turkey. [ABSTRACT FROM AUTHOR]

Variations in lake-levels and hydrology are connected to climatic dynamics over the Trans-Himalaya and Tibetan Plateau (TP). Pangong Tso, a ~140 km long hypersaline lake, is sensitive to changes in air temperature, precipitation and snow-glacier melt over the southwestern TP. The incised tributaries entering the lake expose deltaic sequences constituting topset, foreset and bottomset. Sedimentology, chronology and diatom analysis of delta sediments; and stable isotopic and sclerochronological analysis of gastropods helped delineate the Late-Holocene variation in lake levels, surface temperature and salinity. The elevation of the topsets is considered as representing past lake high-stands from where molluscs were also recovered. Three phased lake level changes are observed during the past 3 ka. The first high-stand (+1.4–3.0 m) was at ~2.8–2.0 ka when lake surface salinity and temperature were 4.67–6.01 ppt (parts per thousand) and 5°C–7°C, respectively, against the modern average values of 7.7 ± 0.09 ppt and 16.1°C ± 2.0°C. Followed by a brief decline, another high-stand (+3.0–3.6 m) is observed at 1.1 ka when the salinity is reduced to 4.03–5.72 ppt and lake surface temperature to 5°C–8°C. A corresponding increase in freshwater diatom concentration is also observed here. The third phase over the past 1 ka witnessed a fall of ~3.6–6 m in lake level that is attributed to an abrupt rise in aridity over the TP. We demonstrate that lake level variation in the region is a function of the variability of the Indian Summer Monsoon (ISM) and the westerlies, however during the high-stand, the hydrology of the lake was dominated by ISM precipitation. [ABSTRACT FROM AUTHOR]

The Qaidam Basin (QB) is a concentrated distribution area and chemical industrial bases of salt lakes in China. Lakes in the QB have been expanding during the past 20 years. Rapid lake expansion resulted in some considerable scientific issues on the protection of salt lake resources and infrastructure, and monitoring of hydrological processes at the lake-basin scale. Although the spatial-temporal trends of lake changes on the Qinghai-Tibet Plateau (QTP) have been well documented, the underlying influencing mechanism and hydrogeological implications of rapid lake changes in the QB are not well understood. Three lakes in the northern QB were selected to investigate lake water level fluctuations on different time scales based on extensive in-situ monitoring and satellite observations. The influencing mechanism and hydrogeological implications of rapid changes of terminal lakes were discussed in combination with the reported increasing precipitation rate and mass balance of glaciers in the northern QTP. Results reveal the following: (1) the fluctuation pattern of Sugan Lake was asynchronous and out of phase with that of Xiao Qaidam and Toson Lakes during the monitoring period; (2) Sugan Lake water rose gradually, and the rise interval was from late April to early July. In contrast, Xiao Qaidam and Toson Lakes took on a rapid and steep rise, and the rise intervalwas from late July to September; (3) the influencing mechanisms for rapid lake fluctuations are controlled by different factors: glacier and snow melting with increasing temperature for Sugan Lake and increasing precipitation for Xiao Qaidam and Toson Lakes; (4) in accordance with different intervals and influencing mechanisms of rapid lake expansions in the QB, hydrological risk precaution of lakes and corresponding river catchments was conducted in different parts of the basin. This study provided an important scientific basis for assessing the hydrological process and hydrological risk precaution, and protection of salt lake resources along with rapid lake expansions in the arid area. [ABSTRACT FROM AUTHOR]

During the last deglaciation and middle Holocene, rapid climatic changes occurred repeatedly. Previous research has primarily focused on investigating these periods in East Asia's coastal and inland regions of the Eurasian continent. In contrast, a limited number of studies have reported on climate change and its environmental impacts in island areas near the Pacific Ocean. This study aims to reconstruct paleosol drainage conditions and lake water level fluctuations in the Suwa Basin, an inland basin in central Japan, after the last deglaciation. We utilize the identification of paleosols and the geochemistry of lacustrine sediments to discuss climate change and its impacts on terrestrial environments in the East Asian coastal region. During the Last Glacial Maximum, the basin experienced a lowstand period; meandering fluvial systems led to the development of dry and well-drained paleosols. The lacustrine environment expanded between ca. 16 cal kyr BP and 5 cal kyr BP during a transgressive period. Short-term lake-level fluctuations were reconstructed by examining repeated paleosol development and changes in the bulk SiO 2 content originating from biogenic silica in lacustrine sediments. Our data suggest that the lake's water level fell at ca. 12 cal kyr BP, 8 cal kyr BP, and 7 cal kyr BP. After 5 cal kyr BP, thin paleosols repeatedly formed during short exposure times due to the rapid sedimentation rate in the delta system, which corresponds to the highstand period. Short-term fluctuations between 16 kyr BP and 5 kyr BP, in the lake water level in the inland basin of the Japanese Islands was influenced by drying and cooling trends in the East Asian coastal region, as well as declines in sea surface temperatures in the western tropical Pacific Ocean. These fluctuations roughly synchronize with the Younger Dryas stadial and an 8.2 ka cooling event. Changes in precipitation, which responded to fluctuations in the East Asian summer monsoon intensity and tropical depressions, likely regulated the lake water level. These findings imply the predominant influence of paleoclimate fluctuations over thousands of years on the hydrological regime of lake systems across the island area of the East Asia. • Changes in lake water levels in central Japan in last 16 kyr were clarified. • 1000-yrs scale lake level changes occurred after the last deglaciation. • The lake level declines coincided with the Younger Dryas and an 8.2 ka event. • It shows effect of high latitude climate changes on lake systems in coastal East Asia. [ABSTRACT FROM AUTHOR]

The wetland ecosystem and its driving mechanism are significance impact on the ecological environment and the sustainable development of semi-arid regional economy. Agricultural and industrial land use/land cover change (LUCC) is also important for wetland system. The Daihai wetland (DW) in Inner Mongolia has been suffering from severe environmental problems such as water resource shortages and wetland areas decrease. We analyzed spatiotemporal LUCC at the catchment scale of Daihai Lake, which has recently exhibited a dramatic loss of water area, and investigated the potential role of climatic changes and human activities in the wetland loss. From 1976 to 2015, the arable land and construction land increased by 71.72 and 15.81 km2, with ranges of 18.72% and 39.61%, respectively. Meanwhile, the wetland area decreased by 84.47 km2, accounting for 29.07% of the area in 1976. From 1960 to 2015, the area of Daihai Lake decreased by 100.73 km2, diminishing to 37.09% of the area in 1960, and the lake storage accordingly shrank from 12.9 × 108 to approximately 3.9 × 108 m3. The lake level also rapidly declined. From 1962 to 2014, the lake water mineralization, total nitrogen (TN), and total phosphorus (TP) increased by 2410, 7.86, and 0.182 mg L−1, respectively. The pollution sources included not only mineral fertilizers and pesticides, but also livestock, poultry breeding, aquaculture, and rural household waste. The lake area decreased with increasing agricultural development, Daihai power plant (DHPP) water consumption, and catchment climatic dryness. Thus, the urgent implementation of effective restoration and mitigation measures are needed. [ABSTRACT FROM AUTHOR]

Inter-regional correlation and comparison of paleogeographic events on the basis of a common methodological approach in the interpretation of geological, geochemical and palaeobotanical data on the example of the Baltic Lake District was carried out. The data obtained from the study of lake sediments are important in paleogeographic reconstructions of past events. Their analysis allowed us to restore the integrity and consistent picture of the dynamics of lake levels as an indicator of the evolutionary history of the natural environment of the region in the last 14 000 years. General patterns of sedimentation and lake level fluctuations are primarily concerned with the global trend of warming in the early post-glacial period, the disappearance of permafrost. Further changes in the character of sedimentation is determined by climatic cycles of the Holocene and the stage of change continental.

Abstract. Sediment cores from six lakes in northern, central, and southern Belarus were eõamined to establish correlationsbetween changes in lake conditions and catchment evolution since the Older Dryas. Detailed studies were conducted in three areaswith highly different landscape development history. Common patterns and synchronism in lake sedimentation and fluctuations aremore diverse during the Late Glacial and early Holocene, mainly due to the general tendency of climate warming at the beginning ofthe postglacial epoch and disappearance of permafrost, which led to the increase in infiltrating processes. During the latter half of theHolocene lake level changes were asynchronous in different regions of Belarus. At that time most of the existing differences werecaused by local factors.

The Qehan Lake Basin (QLB) and its system of lakes are located in a marginal monsoon zone and are extremely sensitive to global climate change. In this paper, using aerial photographs from different periods, in addition to MSS, TM, and ETM images, and combining these with regional topographic maps, we analyze lake area changes from 1958 to 2010 and the relation between Qehan Lake (QL) and climate variability. Our results indicate that there was a relatively high lake level in 1959, when the area and volume of the lake were 118.9 km and 151.9 × 10 m, respectively, but this level was subject to a shrinking trend until 2010, when the lake area was only 28.1 km, and the water volume was 41.1 × 10 m. West Qehan Lake (WQL) has experienced severe water shrinkage and lake level fluctuation. In 1958, WQL was 80.2 km in area and 124.1 × 10 m in volume. However, due to a rapid decrease in precipitation and increases in both temperature and evaporation, it began to dry up in 2002. The WQL Water area decreased by 1.82 km/a, and the lake level declined by 7 m during 1958-2002, so it became an ephemeral lake. [ABSTRACT FROM AUTHOR]

Hannaea baicalensisis a benthic pennate diatom that predominantly grows at depths of less than a metre attached to rocks and filamentous algae in Lake Baikal, Russia. This narrow zone at the edge of the lake is subject to frequent wave action and lake level fluctuations, which combine with other factors to affect seasonal abundance. During ice cover from January to May in 2008, when lake levels decreased from 42 to 14 cm above datum,H. baicalensiscell abundance remained low (0.39 × 106cells cm–2). The main period of net cell increase occurred in autumn, when there was a period of stable lake level (±10 cm changes in water depth) that coincided with the return of nutrients during autumn overturn. Cell abundance reached 1.52 × 106cells cm–2on 31 October. Alongside the changes in abundance, cyclic size changes in cell apical lengths were found (40 to 144 µm), which were associated with timing of the length of the life cycle. Size decline occurred in both spring and autumn, with an average decrease in apical length of 36 µm per year. It took two years for the mean apical length of a single cohort to decrease from 128 µm to 56 µm, which was then below the threshold (< 65 µm) for initiation of size regeneration. [ABSTRACT FROM PUBLISHER]

Lake overgrowing is a natural phenomenon, however, the controlling factors of this process are not completely understood. Geological drillings are an important source to help clarify the issue. In the paper, geological cross-sections through biogenic sediments that fill the lake basins in the Uściwierskie Lowering and Brzeziczno Lake were presented and discussed. In the Lake Brzeziczno basin, lake sediments fill-in most of the basin volume and are often interlayered with moss remains. Fine-detrituous gyttja is overlain with coarse-detrituous gyttja, covered by peat sediments, mainly sedge-moss peat. A floating mat is encroaching on the lakes. In lake basins of Uściwierskie Lowering, calcareous-detrituous gyttja dominates the lakes sediments, filling-in most of the volume of the basins. On the western shores of lake basins, sedge-moss peat covers lake sediments but eastern shores remain deprived of sediments due to long-term lake level fluctuation and wind activity. Lake overgrowing models are discussed. We suggest that dynamic models, which include lake level fluctuations, better explain lake overgrowing then the classic, static hydroseral model. [ABSTRACT FROM AUTHOR]

Late Pleistocene and/or Holocene high-resolution palynological studies are available for the south basin of the Caspian Sea (CS), the world's largest lake. However, the north and middle basins have not been the object of high-resolution palynological reconstructions. This new study presents the pollen, spores and dinoflagellate cysts records obtained from a 10 m-long sediment core recovered in the middle basin, which currently has brackish waters and is surrounded by arid and semi-arid vegetation. An age–depth model built based on six radiocarbon dates on ostracod shells indicates that the sequence spans the period from 14.47 to 2.43 cal. ka BP. The present palaeoenvironmental study focuses on the top 666 cm, or from 12.44 to 2.43 cal. ka BP. At the vegetation level, the Younger Dryas is characterised by an open landscape dominated by desert vegetation composed by Amaranthaceae with shrubs and salt-tolerant plants. However, although the Early Holocene is also characterised by desert vegetation, it is enriched in various shrubs such as Ephedra and Calligonum , but tree expansion is not important at the Holocene onset. After a major shift at 8.19 cal. ka BP, the Middle Holocene displays now both the character of desert and of steppe, although some trees such as Quercus and Corylus slightly spread. The Late Holocene records steppe vegetation as dominant, with more tree diversity. Regarding the lacustrine signal, the dinocyst assemblage record fluctuates between slightly brackish conditions highlighted by Pyxidinopsis psilata and Spiniferites cruciformis , and more brackish ones – similar to the present day – with the dominance of Impagidinium caspienense . The Late Pleistocene is characterised by low salinities, related to the Khvalynian highstand. From 11.56 cal. ka BP, slightly more saline waters are reconstructed with an increase of I. caspienense for a period of 1000 years, which could be attributed to the Mangyshlak lowstand. From 10.55 cal. ka BP, low salinity conditions return with remains such as Anabaena and Botryococcus abundant until 8.83 cal. ka BP, followed by a slow, progressive decrease of P. psilata and S. cruciformis until 4.11 cal. ka BP, which is the main assemblage change at lacustrine scale. Since then, higher salinities, similar to the present one, are reconstructed. Finally, Lingulodinium machaerophorum starts its development only at 2.75 cal. ka BP, in the Late Holocene. The present research revealed fundamental differences from previously published sea-level curves, in that a 6000 yr-long highstand suggested by low salinities is shown between 10.55 and 4.11 cal. ka BP. Amongst other arguments, using a comparison to a similar palynological regard but in the south basin, a N–S salinity gradient that is the reverse of the present one across the CS, suggests that the Amu Darya was flowing in the CS. Hence the CS levels during the Late Pleistocene and Holocene were influenced by a combination of precipitation over the high European latitudes and the indirect influence of the Indian summer monsoon over the Pamirs. [ABSTRACT FROM AUTHOR]

Today, the settlement site of Luokesa 1 (L1) lies under water at the northern edge of Lake Luokesa in the Baltic Uplands, south-eastern Lithuania. Its 60 cm-thick Late Bronze-Early Iron Age cultural layer lies on top of lake marl. During excavations in 2008 and 2009, core samples at L1 were taken for the purpose of multidisciplinary investigations. From this material, five on-site pollen diagrams were created in parallel with geo-archaeological investigations and the examination of the botanical macro-remains. Two of these cores mainly comprised the cultural layer, another two consisted largely of the underlying lake marl and the fifth contained primarily the transition from the lake marl to the cultural layer. The chronological sequence was established through 11 AMS dates. The woodland history, starting from the Late Atlantic period, was recorded. The Quercetum mixtum values are quite low in the Subboreal, with the coniferous forest consisting mainly of Pinus and, though significantly less, Picea. At the transition to the cultural layer (Subatlantic) the pollen curves are highly variable, showing peaks in the curves for Betula and Alnus. Pollen from aquatic plants is also present. Changes in riparian vegetation and turbulent sedimentation conditions are to be expected and can be explained by a drop in the water level. As L1 was located on damp ground at that time, water influxes alternating with dry episodes were observed. In the area around L1 the sedge belt was less pronounced, and riparian woodland extended all the way to the shores of the lake. Pollen analyses of four sheep/goat dung samples provide information on the grazing season and pasture location of these domestic animals. The paper also discusses layer formation processes such as water level fluctuations and hiatuses. [ABSTRACT FROM AUTHOR]

The geomorphological map of the Lake Tana basin (15,077 km2, Nile basin, Ethiopia) presented in this paper was prepared from fieldwork data, maps and satellite data that were processed with a geographic information system (GIS). It contains four major components: (i) hydrography, (ii) morphology and morphometry, (iii) materials and (iv) processes at a scale of 1:500,000. The geomorphological setting of the basin consists of lavas that erupted from fissures or (shield) volcanoes during the Tertiary and Quaternary eras, were uplifted and eroded primarily by water. Lake Tana emerged through a combination of a lava barrier blocking the Blue Nile to the south and by epirogenetic subsidence. When the lake reached its maximum extent, extensive lacustrine plain (e.g. Fogera and Dembia plains) were created, river valleys and basins were filled with sediment and higher lying topography was eroded. Today, the lake plays a lesser role in landscape formation because of a decreased extent (3041 km2) compared to the ancient maximum (6514 km2). Dominant processes today are fluvial and subaerial. Recent (1886–2010) changes in the lake coastline are small with the exception of the delta formed by Gilgel Abay, which has increased disproportionally over the last 15 years. This indicates a large input of sediment which is mainly due to rivers flowing through Quaternary lavas. The recent sediment input increase is most probably related to human induced land-use changes. [ABSTRACT FROM AUTHOR]

Abstract: Episodic discharges from the Laurentide Ice Sheet are considered to be one of the major causes of climate oscillations during the glacial to interglacial transition. These outburst floods disrupted thermohaline circulation and might have caused cooling events in the North Atlantic region and beyond, including the Younger Dryas, Preboreal Oscillation, and 8.2-ka events. However, few terrestrial sedimentary records show regional climate changes directly linked to outburst floods during the early Holocene. Here we present lithologic and isotopic data from Silver Lake in northern New Jersey to document temperature and moisture changes during the early Holocene and to discuss possible linkage with outburst flooding events. The lithologic record shows multiple intervals with coupled decreases in carbonate and increases in organic matter during the early Holocene, suggesting lower lake levels and drier climate conditions. Simultaneous with these changes were decreases in carbonate δ18O values, likely reflecting a decrease in air temperature during these dry periods. The apparent correlation of these sedimentary events at Silver Lake with documented outburst floods from the melting ice sheet suggests a possible causal connection, implying that the climate in the Mid‐Atlantic region was extremely sensitive to perturbations of ocean circulation. [Copyright &y& Elsevier]

Abstract: Dendrogeomorphological research was conducted along a volcanic caldera lake of Bolsena in central Italy, Latium region, in order to investigate the erosion process that affects its coastline. Most of the trees sampled were black poplars (Populus nigra L.) with root systems differently exposed. The cores taken from trunks show growth stress (suppression) at different times according to the distance of the tree from the shoreline. Results of the morphological analysis of the root systems were used as a qualitative estimate of the erosion process developing an erosion map of the lake''s shoreline. The dating of suppressions was used to calculate the main horizontal erosion rate at different shoreline sectors. The most intense erosion was recorded on the southern and northern shore, affected by the strongest and long-lasting winds (mean erosion rate at southern coast=0.092m/year, northern coast=0.064m/year, eastern coast=0.049m/year, western coast=0.028m/year). The age of the living trees along the shore points out that the erosion started at least in the 1970s (one of the highest lake level episode) and it is still in progress. [Copyright &y& Elsevier]

1. A study was conducted on the northern shore of Lake Victoria (Uganda) to determine the factors controlling the occurrence of floating root mats and the influence of the floating mats on the distribution of emergent vegetation. 2. Environmental conditions within 78 bays in the study area were characterised using bay size, wave exposure, water depth, littoral slope, sediment characteristics and water level fluctuations. Emergent plants that form floating root mats occur along the shores of these bays. The way in which commonly occurring shoreline vegetation was distributed across a wave-exposure gradient was compared with their distribution across a water level fluctuation gradient. 3. Results suggested that wind–wave action and water level fluctuations are important factors determining the occurrence of floating mats. Mat-forming plants occur in the most sheltered locations along the shore and in waterbodies with modest water level fluctuations. 4. The ability to form mats facilitated the lakeward expansion of emergent plants. Plants forming floating root mats had a larger depth range than non-mat forming plants. 5. The initiation mechanisms for the floating mats of emergent vegetation in Lake Victoria appear to be: (i) invasion of mats of free-floating plants by emergent vegetation; and (ii) detachment of emergent plants from the lake bed following flooding. 6. The formation of floating mats comes with a cost and benefit to emergent plants. The cost is increased vulnerability to damage by water level fluctuations or wind–wave action, leading to reduced horizontal distribution. The benefit is that deep flooding is avoided, thus increasing vertical distribution. The net effect may be to lead to dominance of mat-forming plants in low-energy environments and non-mat-forming plants in high-energy environments. [ABSTRACT FROM AUTHOR]

Abstract: The increasing use of magnetic parameters as a proxy for environmental change necessitates the understanding of processes that link magnetic properties of sediments, especially organic-rich lake sediments, and environmental change. To explore the magnetic mineral-paleoenvironment link, we have recovered a 14,000 yr mineral-magnetic record from White Lake, a hardwater lake containing organic-rich sediments in northwestern New Jersey, USA. Pre-14 ka (1 ka=1000 cal yr BP) sediments are dominated by clays, and the magnetic variations of the clays recorded the deglaciation process, the initial development of the lake, and the stabilization of the watershed. The rapid increase in organic matter and carbonate around 14 ka likely marks the Bølling warming event. The marl sediments were deposited from 14 to 11 ka and displayed a continued decline in magnetic mineral concentration, which indicates increasing marl precipitation in the lake and stabilization of the watershed by vegetation growth. The Holocene gyttja-dominated sediments generally have weak magnetizations. However, yellowish marl layers in the Holocene sediments display strong magnetizations. The strong magnetization of marl layers at ∼1.3, 3.0, 4.4, and 6.1 ka probably resulted from oxidation of the precipitated marl sediments near to shore, which were then eroded, transported, and redeposited during periods of low lake levels. This study demonstrates that multiple magnetic parameters can provide a more detailed and robust interpretation of environmental change than lithologic data alone. [Copyright &y& Elsevier]