Lake Surface Water Research Articles

Lake surface water temperature in China from 2001 to 2021 based on GEE and HANTS

Lake surface water temperature in China from 2001 to 2021 based on GEE and HANTS

How can scorching weathers alter lake surface water temperature? Explore the long-term effects

How can scorching weathers alter lake surface water temperature? Explore the long-term effects

Characterizing Chromophoric Dissolved Organic Matter Spatio-Temporal Variability in North Andean Patagonian Lakes Using Remote Sensing Information and Environmental Analysis

Chromophoric dissolved organic matter (CDOM) is crucial in aquatic ecosystems, influencing light penetration and biogeochemical processes. This study investigates the CDOM variability in seven oligotrophic lakes of North Andean Patagonia using Landsat 8 imagery. An empirical band ratio model was calibrated and validated for the estimation of CDOM concentrations in surface lake water as the absorption coefficient at 440 nm (acdom440, m−1). Of the five atmospheric corrections evaluated, the QUAC (Quick Atmospheric Correction) method demonstrated the highest accuracy for the remote estimation of CDOM. The application of separate models for deep and shallow lakes yielded superior results compared to a combined model, with R2 values of 0.76 and 0.82 and mean absolute percentage errors (MAPEs) of 14% and 22% for deep and shallow lakes, respectively. The spatio-temporal variability of CDOM was characterized over a five-year period using satellite-derived acdom440 values. CDOM concentrations varied widely, with very low values in deep lakes and moderate values in shallow lakes. Additionally, significant seasonal fluctuations were evident. Lower CDOM concentrations were observed during the summer to early autumn period, while higher concentrations were observed in the winter to spring period. A gradient boosting regression tree analysis revealed that inter-lake differences were primarily influenced by the lake perimeter to lake area ratio, mean lake depth, and watershed area to lake volume ratio. However, seasonal CDOM variation was largely influenced by Lake Nahuel Huapi water storage (a proxy for water level variability at a regional scale), followed by precipitation, air temperature, and wind. This research presents a robust method for estimating low to moderate CDOM concentrations, improving environmental monitoring of North Andean Patagonian Lake ecosystems. The results deepen the understanding of CDOM dynamics in low-impact lakes and its main environmental drivers, enhance the ability to estimate lacustrine carbon stocks on a regional scale, and help to predict the effects of climate change on this important variable.

Nymphaea lotus Distribution in Oguta Lake: Implications for Heavy Metal Pollution in Surface Water and Sediments

Water quality is increasingly deteriorating and has affected lakes, which are important sources of freshwater. Heavy metals are of great concern because they are mostly toxic and resistant to decomposition. Aquatic macrophytes serve as stable biological filters that purify water bodies by accumulating dissolved metals and toxins in their tissues. Given their ability to trap various toxic heavy metals, the macrophyte Nymphaea lotus, which is observed on the surface waters of Oguta Lake, was studied to estimate the concentrations of six heavy metals in the water, sediment, and macrophytes. This was achieved by studying the spatial and temporal distribution of Nymphaea lotus in the lake and analysing the concentrations of heavy metals in the surface water, macrophytes, and sediment samples. Descriptive statistics, exploratory data analysis, and correlation analysis were used to analyse data obtained. Results revealed that the population of Nymphaea lotus declines over time from June to November in all regions. Upstream had the highest concentration of macrophytes (64%), while the downstream area has the lowest (2%). The heavy metal concentrations in the three samples ranges from 0.16 mg/kg to 2.96 mg/kg in sediments and Nymphaea lotus, and from 0.16 mg/L to 2.16 mg/L in water, with lead showing the highest concentration across all sample type. This highlights heavy metal contamination in the lake. The sparsely populated Nymphaea lotus exhibits selective bioaccumulation of lead, mercury, and zinc, while it seems to exclude or inefficiently absorb arsenic and chromium. Correlation analysis suggests a close interdependence between the concentrations of metals in sediments, water, and macrophytes, with sediments playing a key role in both water contamination and macrophyte metal absorption. Corrective and preventive measures should be taken to restore the lake.

A new approach to three-dimensional monitoring of surface changes in lakes: application of three-way data analysis model in Lake Burdur, Turkey.

Lakes are areas of ecological significance that host a wide range of living species. Therefore, monitoring changes in lake surfaces is critical for ecosystem preservation. Since conventional methods based on one-dimensional data analysis have limited capacity to analyze complex systems, they may not always produce the desired results in examining surface change. In this regard, a novel approach based on a three-way analysis model of a multi-temporal dataset was improved for the first time to monitor surface changes in Lake Burdur between 2014 and 2023 in terms of latitude, longitude, and year modes. The newly proposed approach, based on the deconvolution of a multi-temporal data series, provided a new way and an alternative approach with a three-dimensional perspective for the simultaneous prediction of changes in latitude, longitude, and relative quantity profiles of Lake Burdur between 2014 and 2023. The proposed approach is based on the parallel factor analysis (PARAFAC) modeling of the multi-temporal datasets. The change in the lake surface as water levels were monitored from latitudinal and longitudinal profiles was obtained by applying the PARAFAC model to the multi-temporal data array. In the same model, the change in lake water surface over the years was determined from the relative quantity profile. The results obtained from the three-way analysis model were compared with the results provided by the conventional method. It was concluded that the findings of this study could provide valuable information to researchers and policymakers in developing effective strategies to analyze changes in lake surfaces in future studies.

Periodically asymmetric responses of deep chlorophyll maximum to light and thermocline in a clear monomictic lake: Insights from monthly and diel scale observations

Deep chlorophyll maximum (DCM), a chlorophyll peak in the water column, has important implications for biogeochemical cycles, energy flow and water surface algal blooms in deep lakes. However, how an observed periodically asymmetric DCM response to environmental variables remains unclear, limiting our in-depth understanding and effective eco-environmental management of deep lakes. Based on both monthly field investigations in 2021 and diel continuous observations in 2021–2023 in clear, monomictic Lake Fuxian, Southwest China, the temporal dynamics and drivers of DCM were examined and periodic features of DCM were found, with a formation period (FP, February–July) and a weakening period (WP, August–December). On the monthly scale, although DCM dynamics were partly attributed to thermocline structures, the role of light penetration depths varied with period. In the FP, the influence of light on DCM was direct, i.e., increased depth and thickness but decreased magnitude. Differently, the influence of light mainly occurred by affecting thermocline structures in the WP, where water quality was another important driver. On the diel scale, light was a major reason for a thicker and lower (magnitude) DCM during day than at night, and the response of DCM to environmental factors between the FP and WP differed also more during day. This periodically asymmetric response of daytime DCM not only being caused by light but possibly also related to other physical factors such as lake surface water temperature, wind speed and precipitation. Bayesian network modelling suggested that water darkening and stratification intensification may promote a shallower, thinner and larger (magnitude) DCM in both FP and WP, but achieving such changes in DCM requires different light and thermocline thresholds. Our findings provide new information valuable for modelling DCM and for predicting the related surface algal blooms in deep lakes under climate change and eutrophication.

Global patterns of lake microplastic pollution: Insights from regional human development levels

Microplastics have emerged as a pervasive pollutant across various environmental media. Nevertheless, our understanding of their occurrence, sources, and drivers in global lakes still needs to be completed due to limited data. This study compiled data from 117 studies (2016–May 2024) on microplastic contamination in lake surface water and sediment, encompassing surface water samples in 351 lakes and lake sediment samples in 200 lakes across 43 countries. Using meta-analysis and statistical methods, the study reveals significant regional variability in microplastic pollution, with concentrations ranging from 0.09 to 130,000 items/m3 in surface water and from 5.41 to 18,100 items/kg in sediment. Most microplastics were under 1 mm in particle size, accounting for approximately 79 % of lake surface water and 76 % of sediment. Transparent and blue microplastics were the most common, constituting 34 % and 21 % of lake surface water and 28 % and 18 % of sediment, respectively. Fibers were the dominant shape, representing 47 % of lake surface water and 48 % of sediment. The primary identified polymer types were polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). Countries like India, Pakistan, and China had higher contamination levels. Positive correlations were found between microplastic abundance in surface water and factors like human footprint index (r = 0.29, p < 0.01), precipitation (r = 0.21, p < 0.05), and net surface solar radiation (r = 0.43, p < 0.001). In contrast, negative correlations were observed with the human development index (r = −0.61, p < 0.01) and wind speed (r = −0.42, p < 0.001). In sediment, microplastics abundance correlated positively with the human footprint index (r = 0.45, p < 0.001). This study underscores the variability in microplastic pollution in global lakes and the role of human activities and environmental factors, offering a valuable reference for future research.

Landsat data reveal lake deoxygenation worldwide

Dissolved oxygen (DO) is a fundamental requirement for the survival of aquatic organisms, which plays a crucial role in shaping the structure and functioning of aquatic ecosystems. However, the long-term DO change in global lakes remains unknown due to limited available data. To address this gap, we integrate Landsat data and geographic features to develop DO estimation models for global lakes using machine learning approaches. The results demonstrated that the trained random forest (RF) model has better performance (R2 = 0.72, and RMSE = 1.24 mg/L) than artificial neural network (ANN) (R2 = 0.66, and RMSE = 1.39 mg/L), support vector machine regression (SVR) (R2 = 0.62, and RMSE = 1.45 mg/L) and extreme gradient boosting (XGBoost) (R2 = 0.72, and RMSE = 1.29 mg/L). Then, we used the trained RF model to reveal the DO long-term (1984–2021) change in surface water (epilimnetic) of 351,236 global lakes with water area ≥ 0.1 km2. The results show that the average epilimnetic DO concentration of global lake was 9.72 ± 1.07 mg/L, with higher DO in the polar regions (latitude > 66.56 °) (10.87 ± 0.54 mg/L) and lower in the equatorial regions (−5 ° < latitude < 5 °) (6.29 ± 0.63 mg/L). We also find widespread deoxygenation in surface water of global lakes, with a rate of − 0.036 mg/L per decade. Meanwhile, the number of lakes and surface area that experiencing DO stress are continuously increasing, with rate of 39 and 212.85 km2, respectively. Our results offer a comprehensive dataset of DO variation spanning nearly 40 years, furnishing valuable insights for formulating effective management strategies, and enhancing the maintenance of the health of aquatic ecosystems.

Occurrence, distribution, and ecological risks of antibiotics and antibiotic resistance genes in the surface waters of Gaoyou Lake, China.

This work examined the occurrence characteristics and ecological risks of 31 antibiotics across five classes and seven ARGs in the surface waters of Gaoyou Lake. A total of 27 antibiotics, spanning four classes, were detected in the surface waters of Gaoyou Lake, with an overall concentration ranging from 57.5 to 114ng/L and an average of 78.8ng/L. Sulfonamide antibiotics exhibited the highest average concentration at 32.7ng/L. Spatial analysis revealed that antibiotic concentration levels in the western region of the lake were higher than those in other areas. Similarly, ARGs were most abundant in this area, with sulfonamide ARGs demonstrating a notably higher mean abundance than other ARGs. Correlation analysis revealed strong positive associations between sul1 and several antibiotics, including sulfadimidine, sulfamethoxazole, ciprofloxacin, lincomycin, clindamycin, erythromycin, and intl1 (P < 0.05), with intra-group correlations among sulfonamide ARGs exceeding those between different ARG groups. Ecological risk assessment indicated that erythromycin and sulfamethoxazole presented medium risks, whereas roxithromycin, azithromycin, and lincomycin were associated with low risks to aquatic organisms. The ecological risk proportions across monitoring sites were primarily low (10.6%) and moderate (16.7%), with no high-risk areas identified and 72.7% presenting no risk. The cumulative ecological risk quotient (RQcum) suggested a medium-risk level at all surveyed sites.

Disproportionate impact of atmospheric heat events on lake surface water temperature increases

Disproportionate impact of atmospheric heat events on lake surface water temperature increases

Dynamics of the risk of algal blooms induced by surface water temperature in an alpine eutrophic lake under climate warming: Insights from Lake Dianchi

Climate change-induced higher water temperature is increasing the risk of algal blooms (ABs) in eutrophic water bodies. However, it is not well known how and to what extent warming affects ABs risk. In this work, with simple data input (satellite product, lake surface observation, and climate) and method structure (ensemble learning, statistical downscaling, and hierarchical clustering), a systematic lake surface water temperature (LSWT) and ABs risk evaluation system are constructed and applied in a typical eutrophic freshwater lake. The main results are as follows: 1. The warming rate of LSWT and air temperature from 2000 to 2023 reached 0.21 °C/10a and 0.30 °C/10a respectively, resulting in an extended ABs risk in the historical period. 2. The Nash–Sutcliffe efficiency between climate and LSWT reached 0.89, and LSWT showed a significant (p < 0.05) positive correlation with algal density. 3. The escalation of ABs risks mainly spread to spring and autumn in the forthcoming future, the adverse effect of high emission scenarios will evidently emerge in the mid-21st century. Policymakers and catchment managers should be cautious of lake warming and develop countermeasures in advance.

50-year seasonal variability in East African droughts and floods recorded in central Afar lake sediments (Ethiopia) and their connections with the El Niño–Southern Oscillation

Abstract. Understanding past and present hydrosystem feedbacks to global ocean–atmospheric interactions represents one of the main challenges to preventing droughts, extreme events, and related human catastrophes in the face of global warming, especially in arid and semiarid environments. In eastern Africa, the El Niño–Southern Oscillation (ENSO) was identified as one of the primary drivers of precipitation variability affecting water availability. However, the northern East African Rift System (EARS) still suffers from the underrepresentation of predictive and ENSO teleconnection models because of the scarcity of local to regional historical or palaeo-data. In this paper, we provide a 50-year seasonal flood and drought chronicle of the Awash River catchment from the study of laminated sediment from Gemeri and Afambo lakes (central Afar region, Ethiopia) with the aim of reconstructing the magnitude of regional hydroclimatic events. Pluricentimetric micro-laminated lithogenic facies alternating with plurimillimetric carbonate-enriched facies are investigated in both lakes. We couple dating methods including radiocarbon, short-lived radionuclides, palaeomagnetic field variations, and varve counting on both lake deposits to build a high-resolution age model and to discuss the regional hydrosedimentary dynamics of the Awash River over the last ∼ 700 years with a focus on the last 50 years. Using a multiproxy approach, we observe that following a multicentennial enhanced hydrological period, the two lakes have experienced a gradual decrease in river load inflow since 1979 CE, attaining extreme drought and high evaporative conditions between 1991 and 1997 CE. In 2014, the construction of a dam and increased agricultural water management in the lower Awash River plain impacted the erodibility of local soils and the hydrosedimentary balance of the lake basins, as evidenced by a disproportionate sediment accumulation rate. Comparison of our quantitative reconstruction with (i) lake water surface evolution, (ii) the interannual Awash River flow rates, and (iii) the El Niño 3.4 model highlights the intermittent connections between ENSO sea surface temperature anomalies, regional droughts, and hydrological conditions in the northern EARS.

Habitat changes in response to pressures in the Verlorenvlei Estuarine Lake, South Africa

Verlorenvlei is a globally important RAMSAR wetland on the arid west coast of South Africa. A prolonged drought between 2016 and 2021 and increasing competition for water from the agricultural sector resulted in extremely low water levels. We used historical aerial and satellite imagery from 1942 and rainfall and water level data for the past 50 years, to assess habitat changes within the estuarine functional zone of the Verlorenvlei Estuarine Lake. Prior to the drought, lake water levels and water surface area remained stable (1113 ± 27 ha (SE)). Since then, there has been a 64% decrease in open water area, exposing 193 ha of sandbanks, of which 190.9 ha were hyper-sulfidic pyrite-rich. The water in the lower lake was hypersaline ( &gt;100), and in the middle, it was acidic (pH&lt;3). The low water level plus sediment and nutrient input from surrounding agriculture resulted in a localised increase in reeds. Additional pressures, such as fires, have reduced the above-ground biomass of reeds and sedges, potentially altering surface morphology and reducing stored carbon. Despite flooding and filling up in June 2023, the lake remained in an acidic state (3.9–4.3). Similar low-lake level, hypersaline and acidic conditions are predicted to become more common under future climate change scenarios where aridity and extreme weather events are anticipated. Inflow of fresh water into the estuary and control of farming practices are required to keep the Verlorenvlei in a functional state, with long-term monitoring necessary to assess the ecological condition in response to restoration actions.

Lithium capacity of Kazakhstan mineral resource base

Relevance. Weak knowledge of the territory of the Republic of Kazakhstan on lithium raw materials previously mined in the East Kazakhstan region. Aim. To study lithium raw material base in the Republic of Kazakhstan and prospects for the extraction of lithium raw materials. Methods. Content analysis of all information on the subject of the mineral resource base of lithium in the Republic of Kazakhstan. Results. Within the Republic of Kazakhstan, ore deposits of scapolite pegmatites and lithium-bearing greisens-hydrothermal growths are known along alkaline granites. Residual lithium reserves from previously developed rare metal deposits that are equivalent to 36.3 thousand tons of Li2O, predicted resources of known lithium occurrences are estimated at 140 thousand tons of Li2O. It is possible to develop known rare metal deposits with the extraction of tantalum, niobium, beryllium and associated extraction of spodumene concentrate. GRK «Ognevsky Mining and Processing Plant» is already planning to put back to mining of tantalum and beryl (with the associated extraction of spodumene concentrate – up to 2.5 thousand tons/year) at the Bakennoe deposit and processing the resulting ore concentrates at the operating Ulba metallurgical plant of Kazatomprom. With regard to lithium-bearing hydro-mineral resources of the Republic of Kazakhstan, the situation is more complicated, due to the data limitations on the completeness of formation water testing and the reliability of data on surface waters of stagnant lakes. Such oil and gas fields as Karachaganak (up to 196 mg/l Li2O), Kolkuduk (up to 130 mg/l Li2O), Teplovskoe (up to 82.5 mg/l), Urikhtau (up to 52 mg/l) and Western Opak (up to 45 mg/l) are known for high concentration of lithium in formation waters. First two deposits are ready for oil and gas development and production with an annual extraction of up to 1 thousand tons of lithium carbonate. With regard to the lithium content of stagnant lakes of the Republic of Kazakhstan, it should be noted almost total lack of reliable information on sampling their surface waters. Given the fact of finding industrially significant lithium-bearing hydro-mineral lake deposits in adjacent regions of China and Mongolia, it is necessary to intensify the thematic works to assess the lithium content of endorheic lakes throughout the Republic of Kazakhstan, with sampling not only of surface waters, but also of natural brine, lake mud, saline clayey rocks of solonchaks and takyrs.

Co-occurrence of microplastics and heavy metals in a freshwater lake system in Indian Himalaya: Distribution and influencing factors

Microplastic (MP) contamination in freshwater systems is a prevalent and persistent environmental issue, yet their occurrence and distribution remain poorly constrained. The present study examines the MPs abundance in sediment and water samples and factors controlling their distribution in the Manasbal Lake, north-western (NW) Himalaya. Additionally, the study investigates the relationship between heavy metals and the distribution of MPs in sediment, as well as their potential interactions. The MPs counts in lake surface sediment and water samples varied from 840 nkg−1 to 4020 nkg−1 and 13 nL−1 to 89 nL−1, respectively. The MPs distribution in Manasbal Lake exhibited spatial heterogeneity, with the greatest abundance observed in the eastern and northeastern areas near lake inlets. Grain size and land use appear to collectively modulate the variability of MPs in Manasbal Lake sediments. Five main MPs types were identified: beads/pellets, fragments, fibres, foams, and films, with beads being the predominant type. Polypropylene, polyethylene, and polystyrene are the dominant constituents of the observed MPs, with domestic sewage suggested as the predominant source for their abundance in the lake. Furthermore, the contamination factor for heavy metals indicated a high level of lead contamination in surface sediments, while copper and cobalt showed moderate contamination near the lake inlet. The SEM-EDS analysis illustrated the presence of toxic elements such as Hg, Zn, Pb, Cr, Cd, Ni, and Cu to the surface of MPs. This study expands the baseline characterization of MPs in freshwater systems and enhances our understanding of the potential sources and factors influencing MP distribution.

The impact of lake discontinuities on nitrogen biogeochemistry in river networks

River networks connect terrestrial and marine ecosystems through transport of pollutants and nutrients. Lakes represent discontinuities within these river networks, which can be important biogeochemical hotspots, introducing substantial changes to the aquatic environment. Nitrogen is a key macronutrient that can potentially limit or co-limit primary production, but the processes that determine the fate of nitrogen during transport through river-lake networks are poorly understood. We studied three river systems and their lake discontinuities, spanning a range of trophic states and average water residence times, to understand the changes introduced to riverine nitrogen biogeochemistry by lake discontinuities. In-lake processes noticeably altered the concentration and speciation of nitrogen. Annually, lakes reduced up to 44% of nitrate compared to main inflow concentrations, while there was large variability in nitrate dynamics seasonally. The drawdown in surface nitrate concentrations resulted at times in phytoplankton co-limitation by nitrogen in-lake, as well as in the downstream river, where altered nitrogen patterns could persist for several kilometers. However, lakes occasionally subsidized N to downstream rivers as ammonium or dissolved organic nitrogen. Assimilation of nitrate in lake surface waters was one of the dominant processes impacting nitrogen availability; however, stable isotope data revealed an unexpected contribution of nitrification on nitrogen cycling in the epilimnion throughout the year and across trophic gradients. These changes in nitrogen concentration, as well as speciation introduced by lake discontinuities have potentially important consequences for the composition and metabolism of communities in downstream rivers and contribute to our fundamental understanding of freshwater processes.

A database of nutritional strategies of nanoplankton genera present in North American lake surface waters

Abstract A database of nutritional strategies of nanoplankton genera present in North American lake surface waters is presented. This work represents an integrated and updated database of nutritional strategies for nanoplankton genera commonly found in surface waters of North American lakes. We tabulate the nutritional strategies (autotroph, phago-mixotroph and phago-heterotroph) for nanoplankton genera identified during several pan-continental lake surveys: the EPA-NLA surveys conducted in 2012 and 2017 across the continental USA and the NSERC Canadian Lake Pulse survey campaign conducted from 2017 to 2019. We expect that this work will serve others in the plankton community interested in assessing nanoplankton feeding strategies.

Spatiotemporal variability of lake surface water temperature and water quality parameters and its interrelationship with water hyacinth biomass in Lake Tana, Ethiopia.

Urbanization, agriculture, and climate change affect water quality and water hyacinth growth in lakes. This study examines the spatiotemporal variability of lake surface water temperature, turbidity, and chlorophyll-a (Chl-a) and their association with water hyacinth biomass in Lake Tana. MODIS Land/ Lake surface water temperature (LSWT), Sentinel 2 MSI Imagery, and in-situ water quality data were used. Validation results revealed strong positive correlations between MODIS LSWT and on-site measured water temperature (R = 0.90), in-situ turbidity and normalized difference turbidity index (NDTI) (R = 0.92), and in-situ Chl-a and normalized difference chlorophyll index (NDCI) (R = 0.84). LSWT trends varied across the lake, with increasing trends in the northeastern, northwestern, and southwestern regions and decreasing trends in the western, southern, and central areas (2001-2022). The spatial average LSWT trend decreased significantly in pre-rainy (0.01 ℃/year), rainy (0.02 ℃/year), and post-rainy seasons (0.01℃/year) but increased non-significantly in the dry season (0.00 ℃/year) (2001-2022, P < 0.05). Spatial average turbidity decreased significantly in all seasons, except in the pre-rainy season (2016-2022). Likewise, spatial average Chl-a decreased significantly in pre-rainy and rainy seasons, whereas it showed a non-significant increasing trend in the dry and post-rainy seasons (2016-2022). Water hyacinth biomass was positively correlated with LSWT (R = 0.18) but negatively with turbidity (R = -0.33) and Chl-a (R = -0.35). High spatiotemporal variability was observed in LSWT, turbidity, and Chl-a, along with overall decreasing trends. The findings suggest integrated management strategies to balance water hyacinth eradication and its role in water purification. The results will be vital in decision support systems and preparing strategic plans for sustainable water resource management, environmental protection, and pollution prevention.

A dataset of vector and coverage of river and lake surface water in Guangxi, Yunnan, Guizhou (China), and the ASEAN member states

Runoff plays an important role in the water cycle, and information on the distribution of rivers in a watershed is essential for water resources, ecology, environment as well as socio-economic activities in a certain region. The region involving Guangxi, Yunnan and Guizhou in China, and the ASEAN member states is known for cloudy rainfall and distinct mountainous terrain. A comparative analysis of existing river datasets highlights the insufficient characterization of river information in this unique region. To obtain more accurate river distribution data for assessing water resources and the ecological environments, we integrated in this paper the Eurasian continental river vector data (2010) and the ESA land classification data (2020). Following this, we employed an expansion and contraction buffer analysis method to address the issue of river discontinuity. And in this way, we produced a dataset of river surface water in Guangxi, Yunnan and Guizhou in China and the ASEAN member states. After further processing the ESA land classification data, we derived a vector dataset of lake surface water encompassing Guangxi, Yunnan, and Guizhou in China, along with the ASEAN member states. Finally, we calculated the coverage of river and lake surface water and compiled a coverage dataset with a resolution of 1km grid across Guangxi, Yunnan, Guizhou in China, and the ASEAN member states. Comparing with the HydroRIVERS dataset and our water remote sensing datasets (Global Surface water, Esri Land Cover, Dynamic World V1, GRWL), this dataset excels in characterizing the river system in the study area, and provides richer details than the input datasets, as evidenced by the following. This dataset can fill in gaps in the mountainous tributary sections of the Eurasian continent's river vector data from 2010, and effectively address the issue of discontinuous and missing rivers. The dataset can be used to provide basic prior data for water extraction in Guangxi, Guizhou, Yunnan and the ASEAN state members, and it holds great value in flood forecasting and water resources management. Moreover, it can also serve social and economic activities such as ecological preservation, transportation planning, agricultural irrigation and energy use.

Bioprospecting for moderately halophilic eubacteria for potential biotechnological applications from Sambhar Lake, Rajasthan, India

Sambhar Lake an athalassohaline habitat located at 27°58′N 75°55′E, Rajasthan, India is a major source of salt production in the country. From surface lake water, soil, and shore sediments, fifty-nine moderate halophiles were isolated which were subsequently grouped according to shape, colony characteristics, and staining into twenty-two isolates. Fourier transform infrared spectroscopy profiling identifiedthese isolates as eubacterial with characteristic C=O stretching of ester functional groups. Observations further indicatedsimilarity within some Halomonasisolates indicating potential phylogenetic lineages. The FASTA sequences obtained after sequencing with universal bacterial primers were processed for phylogenetic analysis. Predominantly Gram-positive genera like Alkalibacillus, Amphibacillus, Marinococcus, Piscibacillus, Planococcus, Salinicoccus, Staphylococcusand Virgibacilluswith only two Gram-negative strains of Halomonaswere identified. The genus Amphibacilluswas recognizedfor the first time in the study of Sambhar Lake. Despite being moderately halophilic, several isolates exhibited high salt tolerance with growth in 25% salt. All isolates were mesophilic with growth observed between 18-42°C which matches the temperature profile of the region. Analysis of hydrolytic potential identified eighteen isolates as protease producers, thirteen as lipase producers, and ten as cellulase-producing strains. Further evaluation showed the dominance of C10:0, C12:0, C13:0, C14:0, C15:0, C16:0, C17:0, C18:0, C18:1 FAMEs, among which presence of C16:0 and C18:1 fatty acid indicated probable antimicrobial potentials of these strains.