Eco-toxicity and health risk assessment of polycyclic aromatic hydrocarbons in surface sediments of Burullus Lake in Egypt

Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous environmental contaminants of growing concern due to their potential ecological and human health risks.This study presents a comprehensive assessment of PAHs contamination in the surface sediments of Burullus Lake,a vital and second largest delta lake in Egypt.The aim was to evaluate the eco-toxicity and potential health risks associated with the presence of these compounds.Surface seven sediment samples were collected from various drains in the southern part of Burullus Lake.Soxhlet extraction method was employed to extract PAHs(16PAHs)from the sediment sample.Analytically,target compounds were located using HPLC.The results showed that samples contained PAHs levels ranging from 0.038×10^(-6)to 0.459×10^(-6),which is considered heavily polluted by the European standard for PAHs pollution.Additionally,there was no apparent source of PAHs in the ElKhashah drain or the Brinbal Canal,as HPLC found none of the compounds.The most prevalent compound in sediment samples along the study area was fluoranthene.The diagnostic indices in the present study indicated that the hydrocarbons in the region originated from pyrolytic and man-made sources along the drains of Burullus Lake.The principal component analysis(PCA)and diagnostic ratios revealed that coal combustion and pyrolytic sources were responsible for the PAHs contamination in the surface sediments.The non-carcinogenic risk(HI),which is the product of the HQs for the adult and child populations,respectively,was calculated.HI values under 1,therefore,demonstrated that they had no carcinogenic effects on human health.TEQs and MEQs in the sediments of Burullus Lake do not have a cancer-causing impact on people.For the safety of nearby wildlife,aquatic life,and people,all activities that raise petroleum hydrocarbon levels in Burullus Lake must be adequately regulated and controlled.According to the ecological risk assessment,there is little chance that PAHs will be found in the sediments of Burullus Lake.This study underscores the urgent need for effective pollution control measures and regular monitoring of PAHs levels in Burullus Lake sediments to protect the aquatic ecosystem and public health.It also highlights the importance of considering eco-toxicity and human health risks in integrated risk assessments of PAHs-contaminated environments.

Flooding(or breaching)of inter-connected proglacial lakes by cascading overflow in the arid region of Western Mongolia(Mt.Tsambagarav,Mongolian Altai)

This study investigates the glacial lake outburst flood(GLOF)hazards in the Tsambagarav mountain range in Western Mongolia,focusing on the Khukhnuruu Valley and its interconnected proglacial lakes.Over the last 30 years,significant glacier retreats,driven by rising temperatures and changing precipitation patterns,have led to the formation and expansion of several proglacial lakes.Fieldwork combined with satellite data and meteorological analysis was used to assess the dynamics of glacier and lake area changes,with particular focus on the flood events of July 2021.The research reveals a substantial reduction in glacier area,particularly in the Khukhnuruu E complex,where glacier area decreased by 19.3%.The study highlights the influence of increasing temperatures and summer precipitation,which have accelerated ice melt,contributing to the expansion and eventual breaching of lakes.Additionally,lake area changes were influenced by the steepness of the terrain,with steeper slopes exacerbating peak discharge during floods.Of the studied seven lakes(Lake 1 to Lake 7),Lake 1 experienced the most dramatic reduction,with a decrease in area by 73.51%and volume by 84.84%,followed by Lake 7.This study underscores the region's vulnerability to climate-induced hazards and stresses the need for a comprehensive early warning system and disaster preparedness measures to mitigate future risks.

Morphology of crater and caldera lakes in the Far Eastern region of Russia and the features of their development

Volcanic lakes in the Kuril-Kamchatka region are difficult to access,and for this reason,they remain poorly studied,with only scattered and brief data available.The authors have conducted a study of 10 lake basins using modern digital echolocation survey techniques and have also compiled and summarized published data for 15 lakes in the region,calculating their main morphometric characteristics.It has been established that many caldera lake basins are modified by young explosive funnels,extrusive or effusive domes,and exhibit traces of hydrothermal activity.While lakes of the same genetic type in the Kuril-Kamchatka region are similar in depth and depression forms,the group of caldera lakes shows less homogeneity across all morphometric indicators.It was found that the absolute heights of the reservoirs on Kamchatka Peninsula are generally greater than those on the Kuril Islands,as is often the case with the size of their basins.The volcanic lakes under study can rapidly change their volume and shape under the influence of endogenous processes.For the first time for this region,on the base of repeated observations,underwater extrusive dome rate growth and the approximate rates of 2 lake level changes were calculated.Repeated observations of lakes in the Ksudach calderas(Kamchatka)and on Simushir Island indicate approximate rates of level changes:a decrease ranging within 0.5-0.6 m per year(over a 27-year observation interval)and an increase reaching up to 0.26 m per year(over a 48-year interval).The growth rate of the underwater extrusive dome in Lake Shtyubel has averaged 1-1.6 m per year over the past 25 years.This analysis has facilitated the first generalization regarding the morphology and developmental features of crater and caldera lakes in the Kuril-Kamchatka region of Russia,representing an important step in their study.The results obtained will provide a solid foundation for subsequent research in this region and may be of interest to researchers studying other volcanic lakes.

The source of lithium in Lakkor Co Salt Lake on Qinghai-Tibet Plateau,China:evidence from hydrochemical characteristics and boron isotope

The availability of lithium resources is of great significance for the development of modern technologies,as well as for civil and military industries.The Qinghai-Tibet Plateau is a region known for its abundance of lithium-rich salt lakes.However,the specific origin of lithium in these lakes is still unknown,which hinders the advancement of the lithium resource business in this region.To research this issue,this study involved the collection of 20 samples from Lakkor Co Salt Lake on Qinghai-Tibet Plateau,encompassing samples of surface brine,cold springs,fresh lakes,and recharge rivers.The composition of anions and cations in these samples was determined.Furthermore,the analysis extensivelyutilizedthePiperthree-linediagram,Gibbs model,and ion proportion coefficient.The findings of this study indicate that as the moves from the recharge water system to salt lake,there is a transition in water type from strong carbonate to moderate carbonate and weak carbonate,as well as Na sulfate.This research based on a similar source of both lithium and boron,utilized ion correlation analysis and boron isotope study in the Lakkor Co area,and analyzed the source and transporting process of lithium.The main origin of lithium in Lakkor Co is the dissolution of lithiumrich rocks,recharge water systems,and deep hydrothermal fluids.These findings are highly significant in enhancing the foundational data of lithium-rich brine resources in the Qinghai-Tibet Plateau and are beneficial for assessing the future development of such deposits.

Glacier area change (1993-2019) and its relationship to debris cover, proglacial lakes, and morphological parameters in the Chandra-Bhaga Basin, Western Himalaya, India

Glacier inventories serve as critical baseline data for understanding the impacts of climate change on glaciers.The present study maps the outlines of glaciers in the Chandra-Bhaga Basin(western Himalaya)for the years 1993,2000,2010,and 2019 using Landsat Thematic Mapper(TM),Enhanced Thematic Mapper(ETM),and Operational Land Imager(OLI)datasets.A total of 251 glaciers,each having an area above 0.5 km^(2),were identified,which include 216 clean-ice and 35 debris-covered glaciers.Area changes are estimated for three periods:1993-2000,2000-2010,and 2010-2019.The total glacierized area was 996±62 km^(2) in 1993,which decreased to 973±70 km^(2) in 2019.The mean rate of glacier area loss was higher in the recent decade(2010-2019),at 0.036 km^(2),compared to previous decades(0.029 km^(2) in 2000-2010 and 0.025 km^(2) in 1993-2000).Supraglacial debris cover changes are also mapped over the period of 1993 and 2019.It is found that the supraglacial debris cover increased by 14.12±2.54 km^(2)(15.2%)during 1993-2019.Extensive field surveys on Chhota Shigri,Panchi II,Patsio,Hamtah,Mulkila,and Yoche Lungpa glaciers were carried out to validate the glacier outlines and supraglacial debris cover estimated using satellite datasets.Controls of various morphological parameters on retreat were also analyzed.It is observed that small,clean ice,south oriented glaciers,and glaciers with proglacial lakes are losing area at faster rates than other glaciers in the basin.

Significant lake expansion has accelerated permafrost degradation on the Qinghai-Tibet Plateau

In recent years, lakes on the Qinghai-Tibet Plateau have become more responsive to climate change. In September 2011, Zonag Lake in Hoh Xil experienced sudden drainage, the water eventually flowed into Yanhu Lake, which caused Yanhu Lake to continue to expand. The potential collapse of Yanhu Lake could directly threaten the operational safety of the adjacent Qinghai-Tibet Highway, Qinghai-Tibet Railway. To explore the implications of expanding lakes on the surrounding permafrost, we selected Hoh Xil Yanhu Lake on the Qinghai-Tibet Plateau to study the effect of lake expansion on permafrost degradation. The permafrost degradation in the Yanhu Lake basin from October 2017 to December 2022 was inverted using Sentinel-1 satellite image data and small baseline subset interferometry synthetic aperture radar(SBAS-In SAR) technology. Additionally, permafrost degradation from February 2007 and February 2010 was analyzed using advanced land observing satellite phased array-type L-band synthetic aperture radar(ALOS PALSAR) satellite images and differential interferometric synthetic aperture radar(D-In SAR) technique. The results showed that the permafrost around Yanhu Lake experienced accelerated degradation. Prior to the expansion of Yanhu Lake, the average annual deformation rate along the line of sight(LOS) direction was 6.7 mm/yr. After the expansion, the rate increased to 20.9 mm/yr. The integration of spatial-temporal distribution maps of surface subsidence, Wudaoliang borehole geothermal data, meteorological data, Yanhu Lake surface area changes, and water level changes supports the assertion that the intensified permafrost degradation could be attributed to lake expansion rather than the rising air temperature. Furthermore, permafrost degradation around Yanhu Lake could impact vital infrastructure such as the adjacent Qinghai-Tibet Highway and Qinghai-Tibet Railway.

Quantifying freeze-melt dynamics of lakes on the Tibetan Plateau using Sentinel-1 synthetic aperture radar imagery

The ice phenology of alpine lakes on the Tibetan Plateau(TP)is a rapid and direct responder to climate changes,and the variations in lake ice exhibit high temporal frequency characteristics.MODIS and passive microwave data are widely used to monitor lake ice changes with high temporal resolution.However,the low spatial resolutions make it difficult to effectively quantify the freeze-melt dynamics of lakes.This work used Sentinel-1 synthetic aperture radar(SAR)data to derive high-resolution ice maps(about 6 days),then with the aid of Sentinel-2 optical images to quantify freeze-melt processes in three typical lakes on the TP(e.g.Selin Co,Ayakekumu Lake,and Nam Co).The results showed that three lakes had an average annual ice period of 125-157 days and a complete ice cover period of 72-115 days,from 2018 to 2022.They exhibit different ice phenology patterns.Nam Co is characterized by repeated episodes of freezing,melting,and refreezing,resulting in a prolonged freeze-up period.Meanwhile,the break-up period of Nam Co lasts for a longer duration(about 19 days),and the break-up exhibits a smooth process.Similarly,Ayakekumu Lake showed more significant inter-annual fluctuations in the freeze-up period,with deviations of up to 28 days observed among different years.Compared to the other two lakes,Selin Co experienced a relatively short freeze-up and break-up period.In short,Sentinel-1 SAR data can effectively monitor the weekly and seasonal variations in lake ice on the TP.Particularly,this data facilitates quantification of the freeze-melt dynamics.

Quantifying the 2022 drought and spatiotemporal evolution of TWSA in the Dongting Lake Basin over the past two decades

Extreme hydrological events such as droughts and floods have been increasingly influenced by abnormal atmospheric disturbances caused by human activity and global warming.The Dongting Lake Basin(DLB)has experienced challenging circumstances over the past 20 years due to complex climatic variations,leading to extreme flooding and drought.This study aims to investigate the spatiotemporal variation in terrestrial water storage anomalies(TWSA)over the DLB using data from the GRACE/GRACE-FO and GLDAS spanning the latest two decades.A significant decline trend in TWSA is unveiled from July 2019 to May 2023,with the rate of change determined as-1.94 cm/year and-1.99 cm/year based on the GRACE/GRACE-FO and GLDAS,respectively.The GRACE-Drought Severity Index(DSI)is employed to identify and evaluate the severity and spatiotemporal evolution of the 2022 drought event in the DLB.The results accurately capture the drought event,which began in July 2022 and continued until March 2023,with the most severe conditions occurring in October 2022,when the GRACE-DSI value stood at-2.06 and the TWSA decreased by 15.24 cm and 33.51 cm relative to the same month in 2021 and 2020,respectively.Additionally,the daily water level variation at the Chenglingji hydrological gauging station in 2022 broke previous records,reaching a minimum of only 19 m.Comparing the 2022 drought event with the drought events in 2006 and 2011,the impact of drought on vegetation growth conditions was relatively small,but there was still significant vegetation degradation across the DLB.

Distributional and behavioral responses of the wintering Oriental Storks to drought in China’s largest freshwater lake

Extreme droughts are increasing in frequency and severity globally as a result of climate change.Developing understanding of species’responses to drought is crucial for their conservation,especially in regions experi-encing increased aridity.Although numerous studies have investigated birds’responses to drought,the emphasis has primarily been on landbirds.Drought can significantly alter the wetland environments that waterbirds inhabit,but the response of waterbirds to drought remains understudied.In this study,we surveyed the distri-bution and behavior of Oriental Storks(Ciconia boyciana)in Poyang Lake,which is the largest freshwater lake in China.Results indicate that drought-induced catchment areas at the lowest water level limited the total popu-lation size of Oriental Storks in the sub-lakes.Sub-lakes with large catchment areas at the lowest water level demonstrated a capacity to support a larger population of wintering Oriental Storks.Over time,Oriental Storks exhibited a gradual concentration in Changhu Lake,characterized by larger catchments,after resource depletion in sub-lakes with smaller catchments.Additionally,the duration of Oriental Storks’vigilance and moving be-haviors decreased significantly compared with that observed before the drought.After the drought,Oriental Storks increased their foraging efforts,as evidenced by increased presence in deeper water and reaching their heads and necks into deeper water to forage,higher search rates,but lower foraging rates.In accordance with area-restricted search theory,reductions in habitat quality resulting from drought,including extensive fish die-offs,forced Oriental Storks to increase their foraging efforts.Sustaining a specific water area in sub-lakes during droughts can preserve resource availability,which is crucial for the conservation of Oriental Storks.Imple-menting measures such as water level control and micro-modification of lake bottoms in sub-lakes might mitigate the impact of drought on the piscivorous Oriental Storks.

Shallow sub-lakes are essential for sustaining the successful wintering of waterbirds in Poyang Lake,China

For migratory waterbirds,the quality of wintering habitat is related to spring migration and successful breeding in the next year.The availability of food resources in the habitat is critical and varies within water levels.Although the water-level fluctuations in Poyang Lake have been extremely variable interannually in recent years,the wintering waterbird populations have remained relatively stable.Hence,the mechanism of maintaining the stability is worth exploring.This study aimed to compare the distribution of vegetation and herbivorous wa-terbirds in 2015-2016 and 2016-2017,focusing on three shallow sub-lakes and one main lake are.The results showed that the emergence of tubers and the growth of Carex spp.provided a continuous food supply and habitat for wintering waterbirds with a gradual decline in the water level.Shallow sub-lakes supported almost all of the tuber-eating waterbirds(1.42-1.62×10^(5))and most geese(1.34-1.53×10^(6)).However,the main lake area,covered with Persicaria hydropiper,did not provide adequate and accessible food.This resulted in almost no distribution of tuber-eating waterbirds,with only a few geese congregating in early winter.Our results demonstrated that the shallow sub-lakes under human control provided a different environment from the main lake and are key to sustaining the successful wintering of hundreds of thousands of migratory waterbirds in Poyang Lake.Therefore,we recommend refining the anthropogenic management of the shallow sub-lakes to regulate the water level to ensure the carrying capacity of Poyang Lake.

Comparison of fish communities using environmental DNA metabarcoding and capture methods in a plateau Erhai Lake,China

Environmental DNA(eDNA)has been used as an important tool for fish diversity analysis,which can greatly solve the problems in traditional survey methodology.However,little work has been done on the actual monitoring accuracy of eDNA.In this study,we analyzed the current status of fish resources in Erhai Lake in Yunnan,SW China,by dividing the lake into three sectors according to habitat differences,and compared the results of eDNA and traditional capture methods to investigate the shortcomings of the current analysis of eDNA results.A total of 27 fish species were detected by eDNA and traditional capture methods,including 20 and 19 fish species,respectively,and additional differences in fish composition between the two methods.The alpha diversity showed higher fish abundance and lower fish diversity by eDNA method compared to the traditional capture method,demonstrating that eDNA was not superior for use in fish diversity analysis.Fish community similarity analysis showed that community differences were generally significant for eDNA(P<0.05).RDA analysis indicated that environmental factors did not significantly affect fish communities monitored by the eDNA method.However,water temperature,aquatic plants,and water depth had significant(P<0.05)effects on fish communities in the traditional capture method,suggesting that eDNA results are insensitive to the effects of environmental factors.Our results illustrate the effectiveness of eDNA in fish identification and the issues in quantification compared to traditional capture methods.Therefore,combining eDNA with traditional methods is a more effective method for analyzing eDNA metabarcoding,following which the protocols of both quantitative methods can be designed to explore the regularity of eDNA quantification.

Assessment of rehabilitation strategies for lakes affected by anthropogenic and climatic changes: A case study of the Urmia Lake, Iran

Over the last three decades,more than half of the world's large lakes and wetlands have experienced significant shrinkage,primarily due to climate change and extensive water consumption for agriculture and other human needs.The desiccation of lakes leads to severe environmental,economic,and social repercussions.Urmia Lake,located in northwestern Iran and representing a vital natural ecosystem,has experienced a volume reduction of over 90.0%.Our research evaluated diverse water management strategies within the Urmia Lake basin and prospects of inter-basin water transfers.This study focused on strategies to safeguard the environmental water rights of the Urmia Lake by utilizing the modeling and simulating(MODSIM)model.The model simulated changes in the lake's water volume under various scenarios.These included diverting water from incoming rivers,cutting agricultural water use by 40.0%,releasing dam water in non-agricultural seasons,treated wastewater utilization,and inter-basin transfers.Analytical hierarchy process(AHP)was utilized to analyze the simulation results.Expert opinions with AHP analysis,acted as a multi-criteria decision-making tool to evaluate the simulation and determine the optimal water supply source priority for the Urmia Lake.Our findings underscore the critical importance of reducing agricultural water consumption as the foremost step in preserving the lake.Following this,inter-basin water transfers are suggested,with a detailed consideration of the inherent challenges and limitations faced by the source watersheds.It is imperative to conduct assessments on the impacts of these transfers on the downstream users and the potential environmental risks,advocating for a diplomatic and cooperative approach with adjacent country.This study also aims to forecast the volumes of water that can be transferred under different climatic conditions—drought,normal,and wet years—to inform strategic water management planning for the Urmia Lake.According to our projection,implementing the strategic scenarios outlined could significantly augment the lake's level and volume,potentially by 3.57×109–9.38×109 m3 over the coming 10 a and 3.57×109–10.70×109 m3 in the subsequent 15 a.

Temporal and spatial variation and prediction of water yield and water conservation in the Bosten Lake Basin based on the PLUS-InVEST model

To comprehensively evaluate the alterations in water ecosystem service functions within arid watersheds,this study focused on the Bosten Lake Basin,which is situated in the arid region of Northwest China.The research was based on land use/land cover(LULC),natural,socioeconomic,and accessibility data,utilizing the Patch-level Land Use Simulation(PLUS)and Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)models to dynamically assess LULC change and associated variations in water yield and water conservation.The analyses included the evaluation of contribution indices of various land use types and the investigation of driving factors that influence water yield and water conservation.The results showed that the change of LULC in the Bosten Lake Basin from 2000 to 2020 showed a trend of increasing in cultivated land and construction land,and decreasing in grassland,forest,and unused land.The unused land of all the three predicted scenarios of 2030(S1,a natural development scenario;S2,an ecological protection scenario;and S3,a cultivated land protection scenario)showed a decreasing trend.The scenarios S1 and S3 showed a trend of decreasing in grassland and increasing in cultivated land;while the scenario S2 showed a trend of decreasing in cultivated land and increasing in grassland.The water yield of the Bosten Lake Basin exhibited an initial decline followed by a slight increase from 2000 to 2020.The areas with higher water yield values were primarily located in the northern section of the basin,which is characterized by higher altitude.Water conservation demonstrated a pattern of initial decrease followed by stabilization,with the northeastern region demonstrating higher water conservation values.In the projected LULC scenarios of 2030,the estimated water yield under scenarios S1 and S3 was marginally greater than that under scenario S2;while the level of water conservation across all three scenarios remained rather consistent.The results showed that Hejing County is an important water conservation function zone,and the eastern part of the Xiaoyouledusi Basin is particularly important and should be protected.The findings of this study offer a scientific foundation for advancing sustainable development in arid watersheds and facilitating efficient water resource management.

Iteration and evaluation of shale oil development technology for continental rift lake basins

By benchmarking with the iteration of drilling technology,fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin,East China,the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development,drilling and fracturing technologies.The technology system supports the rapid growth of shale oil production and reduces the development investment cost.By comparing it with the shale oil development technology in the United States,the prospect of the shale oil development technology iteration in continental rift lake basins is proposed.It is suggested to continuously strengthen the overall three-dimensional development,improve the precision level of engineering technology,upgrade the engineering technical indicator system,accelerate the intelligent optimization of engineering equipment,explore the application of complex structure wells,form a whole-process integrated quality management system from design to implementation,and constantly innovate the concept and technology of shale oil development,so as to promote the realization of extensive,beneficial and high-quality development of shale oil in continental rift lake basins.

Effects of conductive agent type on lithium extraction from salt lake brine with LiFePO_(4) electrodes

Electrochemical lithium extraction from salt lakes is an effective strategy for obtaining lithium at a low cost.Nevertheless,the elevated Mg:Li ratio and the presence of numerous coexisting ions in salt lake brines give rise to challenges,such as prolonged lithium extraction periods,diminished lithium extraction efficiency,and considerable environmental pollution.In this work,Li FePO4(LFP)served as the electrode material for electrochemical lithium extraction.The conductive network in the LFP electrode was optimized by adjusting the type of conductive agent.This approach resulted in high lithium extraction efficiency and extended cycle life.When the single conductive agent of acetylene black(AB)or multiwalled carbon nanotubes(MWCNTs)was replaced with the mixed conductive agent of AB/MWCNTs,the average diffusion coefficient of Li+in the electrode increased from 2.35×10^(-9)or 1.77×10^(-9)to 4.21×10^(-9)cm^(2)·s^(-1).At the current density of 20 mA·g^(-1),the average lithium extraction capacity per gram of LFP electrode increased from 30.36 mg with the single conductive agent(AB)to 35.62 mg with the mixed conductive agent(AB/MWCNTs).When the mixed conductive agent was used,the capacity retention of the electrode after 30 cycles reached 82.9%,which was considerably higher than the capacity retention of 65.8%obtained when the single AB was utilized.Meanwhile,the electrode with mixed conductive agent of AB/MWCNTs provided good cycling performance.When the conductive agent content decreased or the loading capacity increased,the electrode containing the mixed conductive agent continued to show excellent electrochemical performance.Furthermore,a self-designed,highly efficient,continuous lithium extraction device was constructed.The electrode utilizing the AB/MWCNT mixed conductive agent maintained excellent adsorption capacity and cycling performance in this device.This work provides a new perspective for the electrochemical extraction of lithium using LFP electrodes.

Hydrochemistry of the lakes in the southern Badain Jaran Desert and its paleosalinity reconstruction

The reconstruction of paleohydrology,especially paleosalinity,is an important component of paleoenvironmental research.Researches on the modern characteristics of lake water chemistry and the relationship between lake salinity and hydrochemistry are the basis of paleoenvironment reconstruction.The modern hydrochemical characteristics and the relationship between ion composition and salinity of modern lakes are the basis of paleosalinity reconstruction.In this study,hydrochemical analysis of 21 lakes in the Badain Jaran Desert(BJD)was carried out.The relationships between the Sr/Ca and Mg/Ca ratios and total dissolved solids(TDS)were analyzed.The results show that Na^(+),K^(+),Cl-and SO_(4)^(2-)have high positive correlations with TDS,and Mg^(2+),Sr^(2+),CO_(3)_(2-)and HCO_(3)^(-)have lower correlations with TDS.The Sr/Ca and Mg/Ca ratios do not increase linearly with TDS.Hydrochemical analysis indicates that the studied lakes are in the carbonate precipitation stage and that evaporation is the main factor controlling lake evolution in the BJD.The relationships between the Mg/Ca and Sr/Ca ratios and TDS are mainly influenced by lake evolution stage and the hydrochemical types of the lakes.On the basis of comprehensive previous studies,the factors affecting lake evolution,the Mg and Sr partition coefficients and other hydrochemical parameters that change with lake evolution all affect the relationship between chemical composition and salinity.To reconstruct paleosalinity more accurately,more detailed research on the modern hydrochemical characteristics of lakes and the relationship between the element ratios of carbonates and water salinity should be carried out.

Microscopic analysis on eukaryotic algae and cyanobacteria in nine seasonal lakes and ponds in Vestfjella,Dronning Maud Land,Antarctica

Antarctic continental lakes and ponds are among the most impoverished aquatic environments on earth but many of them support flourishing populations of cyanobacteria,eukaryotic algae,protozoans,and some multicellular animals.In this study,we present results of a microscopic analysis of cyanobacteria and eukaryotic algae from nine diverse types of Antarctic continental water bodies during one austral summer.The results supplement and enlarge our previous studies on the limnological characteristics of the epiglacial and supraglacial lakes and ponds in Dronning Maud Land,an area that has received little attention from limnologists.The taxon with highest frequency among the samples(n=79)was Mesotaenium cf.berggrenii,a eukaryotic Zygnematophyceae,which occurred in 82%of the samples with a maximum cell density of 68 cells·mL^(-1).The taxa with second and third highest frequency were the prokaryotes Gloeocapsopsis(60%)and Leptolyngbya(41%),followed by Chlamydomonas(34%)and Cyanothece(29%).The number of taxa varied between 7-21 among the lakes and ponds,being highest in a supraglacial lake,and lowest in an epiglacial lake.The results did not reveal any obvious correlation between the abundance of any taxa and the water chemistry,but water bodies with inorganic sediments had higher cell densities and biomasses than those without sediment.This suggests the importance of sediment in supporting biological diversity in these ultraoligotrophic lakes and ponds.

Characterization and Assessment of the Quality of the Water and Sediments of the Islands (Moudou and Birguime) of Lake Fitri in Chad and Confirmation of the Strains Isolated by the PCR Method

The problem of access to quality water is a major challenge, as it has a major impact on the socio-economic conditions of people in developing countries. The water from the islands of Lake Fitri is one of the main sources of drinking water for the population. The aim of this study is to characterise and assess the quality of the water and sediment from the islands (Moudou and Birguime) of Lake Fitri, and to confirm the strains isolated using the PCR method. A total of fifty (50) samples of water and fifty (50) sediments from the islands of Lake Fitri were analyzed. Standard methods of microbiological and biochemical analysis of water and sediments were used. Isolated Enterobacteriaceae strains were characterized by API 20 E and API Staph galleries and Salmonella was confirmed by PCR method. Antibiotic resistance was determined using a technique recommended by the antibiogram committee of the French microbiology society (CA-SFM, 2019). The microbiological results for the water showed an abundance of total aerobic mesophilic flora (TAMF) (4.31 × 106 ± 8.05 × 105 and 5.29 × 106 ± 2.55 × 105) on the Birguime and Moudou islands successively. The microbiological results for the sediment from Birguime and Moudou islands showed an abundance of thermotolerant coliforms (E. coli) (2.05 × 105 ± 5.43 × 104 and 2.27 × 105 ± 3.49 × 104) alternately. The results obtained after incubation of the biochemical tests by the API 20E, API Staph gallery and their numerical profile proposed by the Api software confirmed the contamination. The antibiogram results showed the emergence of certain resistances to the antibiotics Tobramycin, Flucytosine, Amikacin and Teicoplani. The PCR results for Salmonella spp strains were confirmed. As a result, strict monitoring of the water on the various islands of Lake Fitri must be carried out throughout the annual cycle, by specialized personnel, to ensure proper bio-monitoring of these ecosystems.

Glacial lakes under climate change: the imperative for comparative studies of microbial carbon metabolism in the Qinghai-Xizang Plateau and the Arctic

Glacial lakes,intimately linked to glacier termini,are crucial landscape features of the Qinghai-Xizang Plateau(QXP,Qinghai-Tibet Plateau)and the Arctic.Climate warming has accelerated glacier retreat and the rapid expansion of glacial lakes in both regions.Despite being typically considered harsh environments,these lakes serve as vital reservoirs for microbial biodiversity and carbon metabolism.In the face of climate change,glacial lake ecosystems over the QXP and the Arctic are undergoing unprecedentedtransformations.Thisopinioneditorial highlights the significance of conducting research and establishing long-term monitoring programs focused on microbial carbon metabolism in these glacial lakes.

Brightness temperature simulation of subarctic lake-ice evolution by HIGHTSI and SMRT model

Microwave brightness temperature(TB)can be used to retrieve lake ice thickness in the Arctic and subarctic regions.However,the accuracy of the retrieval is affected by the physical properties of lake ice.To improve the understanding of how lake ice affects TB,numerical modeling was applied.This study combined a physical thermodynamic ice model HIGHTSI with a microwave radiation transfer model SMRT to simulate the TB and lake ice evolution in 2002-2011 in Hulun Lake,China.The reanalyzed meteorological data were used as atmospheric forcing.The ice season was divided into the growth period,the slow growth period,and the ablation period.The simulations revealed that TB was highly sensitive to ice thickness during the ice season,especially vertical polarization measurement at 18.7 GHz.The quadratic polynomial fit for ice thickness to TB outperformed the linear fit,regardless of whether lake ice contained bubbles or not.A comparison of the simulated TB with space-borne TB showed that the simulated TB had the best accuracy during the slow growth period,with a minimum RMSE of 4.6 K.The results were influenced by the bubble radius and salinity.These findings enhance comprehension of the interaction between lake ice properties(including ice thickness,bubbles,and salinity)and TB during ice seasons,offering insights to sea ice in the Arctic and subarctic freshwater observations.