Lake Water Research Articles

Long-Term Stable Reference Electrodes with High-Pressure Tolerance and Salinity-Independence.

The reference electrode's performance is essential for ensuring the accuracy of electrochemical sensors in marine environments. Yet, the many existing reference electrodes can exhibit sensitivity to salinity variations, potentially leading to inaccuracies in the measurement process. Herein, we have designed a reliable solid-state reference electrode by introducing SiOx-stabilized 1-methyl-3-octylimidazolium bis(trifluoromethyl sulfonyl)imide ([C8mim+] [Ntf2-]) into a P(VdF-co-HFP) matrix with a SPEEK/[C8mim+] [Ntf2-] coated Ag/AgCl as substrate. The SPEEK/[C8mim+] [Ntf2-] coating protects the AgCl substrate, and the incorporation of SiOx improves the compatibility of the IL with the polymer matrix, thereby increasing the electrode's resistance to interference and extending its long-term stability and lifespan. The developed reference electrode showed a stable and rapid response, with potential variations of less than 0.7 mV across various salinity solutions, including practical seawater, lake water, and their mixture samples. During extended periods of 18 days in deionized water and artificial seawater, the electrode demonstrated negligible potential drifts of 0.36 and 0.14 mV/d, respectively. Notably, the electrode could maintain a stable potential even after being stored in a preservative solution for 67 days. Furthermore, the electrode showed a stable response to withstand pressures of up to 100 MPa, covering the vast majority of the seafloor. This innovative reference electrode is capable of maintaining a stable reference potential across various salinities, ionic strength, and full ocean depth, making it versatile for use in diverse aquatic environments, underscoring its significant potential for advancing oceanographic research and enabling new insights into the unexplored depths of oceans.

IDENTIFYING PRINCE VASILY OF KOSTROMA IN «THE TALE OF ICON OF THE MOTHER OF GOD DEDICATED TO SAINT THEODORE STRATELATES, ITS APPEARANCE AND MIRACLES»

The article is devoted to a question that has for a long time confused researchers of «The tale of Icon of the Mother of God dedicated to Saint Theodore Stratelates, its appearance and miracles», a literary monument of the 17th - 18th centuries: which Kostroma prince was named Vasily, as it was him who, according to the Tale, discovered the image of the Mother of God on the branches of a tree near Kostroma city and then supervised the bringing of the icon to Kostroma. In the most famous and widespread edition of the Tale, called the extended one, this prince is called the Grand Prince Vasily Georgieyvich Kvashnya, the grandson of Alexander Nevsky; however, the only Kostroma prince named Vasily known to us is Vasily Yaroslavich, the younger brother of Alexander Nevsky (1241-1276). The article examines the opinions of researchers of the 1st half of the 18th century on this matter: the unknown author of the “Notice of the Grand Prince Vasily of Kostromaˮ of 1719, as well as Leontiy (secular name Luka Pavlov), the hegumen of the Monastery dedicated to Macarius of the Yellow Water Lake and the Unzha, who is now considered to be the author of Kostroma hagiography of Saint Prince George II of Vladimir and the “News of the years in which the icon of the Most Holy Theotokos dedicated to St Theodor appeared in Kostromaˮ. An explanation is offered for the appearance of the patronymic “Georgiyevichˮ in the extended edition of the Tale: its author, Theodor, the archpriest of the Assumption Cathedral of Kostroma Kremlin, actually mixed up the personalities of two brothers, princes, the glorified saint Georgiy Vsevolodovich and Yaroslav Vsevolodovich, and he considered the names Yaroslav and Georgiy to be the family and baptismal names of the same Grand Prince, the parent of Vasily Yaroslavich.

Research on the evaluation index system for happy rivers and lakes: a case study of Xinchang County in Zhejiang Province, China

The “Happy Rivers and Lakes” initiative is an important measure to systematically address the complex water issues in China. It further highlights the effectiveness of constructing happy rivers and lakes based on river health assessments. This approach aims to identify typical practices and the effectiveness of river and lake management and protection at the local level, guiding for river and lake management and conservation work in the new era. This study focuses on county-level administrative units and develops a research framework for the evaluation index system of happy rivers and lakes. A total of 11 primary indicators and 22 secondary indicators are selected from aspects such as river and lake safety, water resources, water environment, biodiversity, and social services. The evaluation and analysis are conducted around the Chengtan River, Huangze River, and Xinchang River, as well as two large reservoirs in Xinchang County. The results show that the comprehensive evaluation score of happy rivers and lakes in Xinchang County is 92.66, categorizing it as a model of happy rivers and lakes. The evaluation results aim to provide references and guidance for similar regions inside and outside Zhejiang Province in their research and practical applications related to happy rivers and lakes.

A novel remote sensing method to estimate pixel-wise lake water depth using dynamic water-land boundary and lakebed topography

ABSTRACT Water depth, a fundamental characteristic of a lake, is important for understanding climatic, ecological, and hydrological processes. However, lake water depth data are still scarce due to the high cost of in-situ measurements and the limitations of remote sensing observations. In this study, a novel method was developed to estimate time series of pixel-wise water depths of lakes that have ever exposed their bottom by remote sensing observations. Lake water depths were calculated as the difference between the elevations of the dynamic water surface and the historical lakebed elevations using optical images and DEM data. The method was applied in the Sahel-Sudano-Guinean region of Africa where complex climatic conditions and rare in-situ measurements. Experiments showed that the proposed method could get consistent water depths compared with the HydroLAKES data, i.e. with a MAE of 0.86 m and a RMSE of 1.69 m, and water surface elevations similar to the estimates derived from ICESat/ICESat-2 measurements with a MAE of 3.79 m and a RMSE of 5.92 m. The method can provide pixel-wise information on lake water depth at high temporal frequency, and is expected to provide an efficient solution to gather essential information on lakes.

Spatial Trends of Cadmium and Zinc Concentrations in Water and Enrichments in Surficial Sediments within Nyanza (Winam) Gulf of Lake Victoria (East Africa)

Metal pollution contributes significantly to the environmental degradation of lake ecosystems. The study evaluated the spatial trends in cadmium and zinc concentrations in surface water, un-fractioned and the <63µm grain size fraction (silt and clay) of surficial sediments within Nyanza Gulf, from lake monitoring stations in 2010 and 2012 surveys. Significantly higher Zn total concentrations were found in surface lake water compared to earlier surveys, but cadmium levels were low and not detectable as in previous studies. Variable contents of Zn and Cd were found in un-fractioned and finer sediment fractions. “Much higher sediment Cd contents were found in 2010 compared to other surveys. Major areas under river and urban influences recorded much higher sediment Cd contents than offshore sediments. However, there were no significant differences between Cd and Zn contents between the gulf and main lake zones. Cd sediment enrichment factors were highly variable compared to Zn, which showed a more uniform trend in most of the gulf areas, but Cd sediment enrichment factors appear to increase when compared to previous data. The spatial distribution of Cd and Zn in the surficial sediments show unpolluted to moderate pollution levels, according to geo-accumulation index. Only 4% of Zn samples exceeded the sediment quality threshold effect concentration (TEC) values, but all were below the mid-range effect values. Cadmium is a recognized toxicant and there are potential ecological concerns regarding the variable sediment Cd contents since it has been found previously in bioavailable forms in surficial sediments and 2% of the samples contained Cd (un-fractioned sediment) above the threshold effect concentration during the 2012 survey compared to 51 % in 2010, but none exceeded the severe effect levels”. Continuous monitoring of priority heavy metals is of relevance on the understanding of potential long-term ecological impacts to the lake ecosystem.

Limited Microbial Contribution in Salt Lake Sediment and Water to Each Other’s Microbial Communities

Climate change and human activities have led to frequent exchanges of sedimentary and aquatic microorganisms in lakes. However, the ability of these microorganisms to survive in their respective habitats between saline lake sediment and water remains unclear. In this study, we investigated microbial sources and community composition and metabolic functions in sediments and water in Yuncheng Salt Lake using a combination of source tracking and Illumina MiSeq sequencing. The results showed that 0.10–8.47% of the microbial communities in the sediment came from the corresponding water bodies, while 0.12–10.78% of the sedimentary microorganisms contributed to the aquatic microbial populations, and the microbial contributions depended on the salinity difference between sediment and water. Habitat heterogeneity and salinity variations led to the differences in microbial diversity, community composition, and assembly between sediment and water communities. The assembly of sedimentary communities was mainly controlled by stochastic processes (>59%), whereas the assembly of aquatic communities was mainly controlled by deterministic processes (>88%). Furthermore, sediments had a higher potential for metabolic pathways related to specific biogeochemical functions than lake water. These results provide insights into the survival ability of microorganisms and the mechanisms of microbial community assembly under frequent exchange conditions in saline lakes.

Spatiotemporal Assessment of Water Quality and Quantity of the Kaptai Lake at Rangamati, Bangladesh - An Approach of Remote Sensing, Field Investigation and Laboratory Analysis

Monitoring water quality and quantity is essential for sustainable water resource management. This study investigates changes in the extent and water quality of Kaptai Lake using remote sensing, field measurements, and laboratory analysis. Analysis of Landsat TM/OLI images from 1989, 2000, 2010, and 2021 shows that the lake's water extent ranges from 380 km² (in 2010) to 435 km² (in 2021), with an average of 407.5 km². The extent of water decreased by approximately 3% from 1989 to 2010 and increased by about 5% from 2010 to 2021 due to changing rainfall patterns, dam operations, sedimentation, and land use changes. Seasonal variations in chlorophyll-a concentration and turbidity, analyzed using Sentinel 2B images from 2022 and 2023, indicate mesotrophic to eutrophic conditions and higher turbidity in post-monsoon. The study found that nutrient enrichment from untreated sewage, agricultural runoff, and algal growth affect chlorophyll-a levels, while development activities, excessive rainfall, and sedimentation influence turbidity. Linear regression analyses show strong positive correlation between field obtained and image derived values both for chlorophyll-a (R2 0.621) and turbidity (R2 0.698). Physico-chemical parameters such as pH, EC and temperature have been measured in the field and hydrochemical parameters including, cations and anions have been measured by laboratory analysis to assess the contemporary water quality status. The average values for pH, EC and temperature are 7.55, 119.85 µS/cm and 22.17 °C respectively. The cationic dominance in the studied segment of the Lake is in the order of Ca2+ > Na2+ > Mg2+>K+ > Fe2+ >Mn2+. On the other hand, the anions are in the order of HCO3- > SO42- > Cl- > NO3-. All the physico-chemical parameters of the lake water fall within the Bangladesh Drinking Water Limit (BDWL) and are not linked to chlorophyll-a and turbidity variations. The findings of this study can help mitigate the deterioration of Kaptai Lake by addressing water quality and extent issues, promoting effective and sustainable lake management strategies. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 13(1), 2024, P 121-139

The subarctic ancient Lake El'gygytgyn harbours the world's northernmost 'limnostygon community' and reshuffles crangonyctoid systematics (Crustacea, Amphipoda).

The northward distribution limit of groundwater fauna is generally dictated by the extent of glacial ice sheets during the Pleistocene. However, some taxa can be found far above this limit, sometimes on isolated oceanic islands, implying long-term survival in subglacial subterranean refugia. Here we report a peculiar assemblage comprising two new depigmented and blind (stygomorphic) amphipods from the subarctic ancient lake El'gygytgyn (northern Far East): Palearcticarellus hyperboreus sp. nov. and Pseudocrangonyx elgygytgynicus sp. nov. Molecular phylogenetic analyses based on five markers confirm their affinity to Crangonyctidae and Pseudocrangonyctidae, respectively. Fossil-calibrated molecular dating indicates that the ages of both species predate the onset of Pleistocene glaciations by at least an order of magnitude. Although both species are clearly adapted for subterranean life and are related to groundwater taxa, they are only known from the lake waters (5-170-m depth). Despite being nested within Pseudocrangonyctidae, P. elgygytgynicus has an atypical third uropod that preserves a vestigial inner ramus, a trait characteristic to the monotypic sister family Crymostygidae. Given that this character was the main distinguishing feature between the two families, we propose merging Crymostygidae with Pseudocrangonyctidae. Our findings represent the world's northernmost record of stygomorphic amphipods, emphasising their relictual biogeography and the importance of Lake El'gygytgyn as a long-term, high latitude refugium for ancient pre-glacial fauna. ZooBank: urn:lsid:zoobank.org:pub:3A51D1F8-E65D-4A3A-B663-D5C40272E68B.

Regulating the surface chemistry of covalent organic frameworks for enhancement cationic dye removal and identification.

Simultaneous removal and identification of trace-level cationic dye pollutants from water is both important and challenging owing to their highly polar and complex sample matrices. In this study, three covalent organic frameworks (COFs) were synthesized using 2, 4, 6-triformylphloroglucinol with ethidium bromide (EB) containing positively charged groups, 3, 5-diaminobenzoic acid (DABA) containing negatively charged groups, and p-phenylenediamine (Pa) lacking charged groups. These were named EB-COFs, TpPa-1, and DP-COFs, respectively, and were employed as adsorbents for the extraction and identification of cationic dyes. The adsorption performance of the three COFs toward methylene blue (MB) and crystal violet (CV) was investigated. By incorporating carboxyl groups into DP-COFs, the surface chemistry of the adsorbent was effectively tailored, enabling complete exploitation of selective cationic sites. This facilitated dynamic interactions with cationic dyes through multiple adsorption mechanisms, including electrostatic, π-π, and H-bonding interactions. DP-COFs exhibited high adsorption capacities for MB and CV, achieving 383 and 326mgg-1, respectively. The adsorption behavior was further analyzed using adsorption isothermals, kinetics, and thermodynamics. Moreover, DP-COFs were employed as a matrix in laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) to adsorb and directly identify both cationic dyes without the need for an elution process. This approach demonstrated high sensitivity, high reproducibility, low background interference, and excellent salt tolerance. The limits of detection for MB and CV were 0.12 and 0.04ngmL-1, respectively, representing improvements of 166-fold and 225-fold compared with using DP-COFs solely as a matrix. Recovery rates of both dyes in spiked industrial wastewater and lake water samples ranged from 81.4 to111.1% with RSDs of 1.9-6.3%. These results highlight the high reliability of the proposed method.

Enrichment Characteristics, Risk Evaluation, and Source Apportionment of Heavy Metals in Wabu Lake of Yangtze River to Huaihe River Water Diversion Project

Wabu Lake serves as a crucial junction within the Yangtze River to Huai River Water Diversion Project （Yangtze-Chao Lake-Wabu Lake-Huai River）, where clarifying the status and risk levels of heavy metal contamination in the lake is crucial for the aquatic ecological safety along the route of the project. Surface water and sediment samples from 24 locations in Wabu Lake were collected and analyzed for the contents of heavy metals （As, Zn, Pb, Ni, Cu, Cr, Fe, and Cd）. Risk evaluation and source apportionment of heavy metals in the lake were conducted using the human risk assessment （HRA） model, sediment quality guidelines （SQGs）, and positive matrix factorization （PMF） method. The results showed that the average concentrations of heavy metals （except for Cd and Pb） in the surface water were lower than the class III limits of the surface water quality standard （GB 3838-2002）. The average concentration of heavy metals （As, Zn, Pb, Ni, Cu, Cr, Fe, and Cd） in interstitial water were lower than the Criteria Continuous Concentration （CCC） of the National Recommended Water Quality Criteria. The average contents of As, Zn, Pb, Ni, Cu, Cr, and Cd in the sediment exceeded the background values by factors of 1.78, 1.85, 1.42, 1.77, 1.41, 1.38, and 3.46, respectively. In addition, the heavy metals Pb, Cd, and Cr in the Wabu Lake water posed severe risks to human health, with the cancer risk （CR） value for Cr reaching 6.14×10-5. The sediment quality guidelines （SQGs） indicated that the probability of adverse effects on lakes by As, Ni, and Cr was relatively high. The spatial distribution of risk areas showed that the risk control zones for As, Cr, and Ni in Wabu Lake covered almost the entire lake area. The PMF analysis indicated that the primary sources of heavy metals in Wabu Lake were exogenous inputs from industrial, agricultural, and residential activities in surrounding areas, followed by endogenous pollution caused by enclosed aquaculture. The subsequent focus should be on the pollution of heavy metals Cr, Cd, and Pb in the overlying water of Wabu Lake as well as the sediment ecological safety of As, Cr, and Ni in the sediment.

Using Two Water Quality Indices for Evaluating the Health and Management of a Tropical Lake

With increasing pressure on freshwater resources in developing countries due to population growth, further research and potential interventions are crucial. Lake Tana, located in the headwaters of the Blue Nile, serves as a critical example of these precious freshwater resources. This study evaluated the water quality of Lake Tana for both ecological health and drinking purposes using the Arithmetic Weighted Water Quality Index (AW WQI) and the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI). Samples were collected from 20 lake sampling stations four times between July 2018 and June 2019 to calculate the two water quality indices using ten measured parameters. The average annual AW WQI ranged from good to very poor for ecological health and very poor to unsuitable for drinking water. The CCME WQI categorized Lake Tana’s water quality as poor to fair for both uses. According to the water quality indices, the water quality was most impacted by turbidity, dissolved oxygen, ammonium, and phosphorus. However, except for ammonium, these factors were immaterial for lake management because the lake was nitrogen-limited, and the turbidity resulted from sediment stirred up by waves from the lake bottom, which cannot be managed easily. Dissolved oxygen is related to turbidity. Moreover, the WQIs did not identify two pesticides in the lake that negatively affected the fish. Thus, WQI indices may document water quality changes over time. Therefore, in addition to a favorable economic and political climate, improving lake water management requires insights from experts, the scientific literature, and possibly additional monitoring in addition to what is provided by the WQIS.

The Burden of Bacteria Pathogens Associated with Cage-cultured Nile Tilapia, (Oreochromis niloticus) along the Mwanza Gulf of Lake Victoria, Tanzania

The recently intensified aquaculture projects in Mwanza Gulf of Lake Victoria, Tanzania, have brought about incidences of increased pathogenic bacteria in the lake waters. In some instances, there have been reports of disease outbreaks in cage-farmed fish. This study aimed to identify the prevalence of selected pathogenic bacteria in Nile tilapia, (Oreochromis niloticus) cage-cultured along the gulf. A total of 250 fish from the cage farms and control site were sampled. Bacteria were isolated and identified from the samples through standard bacterial techniques. A total of 10 bacteria genera were identified, where, staphylococcus spp. had the highest prevalence with 34.5%, pseudomonas spp. at 25.9%, Streptococcus spp. at 10.5%, then Lactococuss spp. 15.5%. These results suggest intensive cage farming is likely the main risk factor for increased bacterial prevalence in the gulf. Henceforth, biosecurity measures must be intensified for sustainable healthy fish farming in cages along the Mwanza Gulf.

A Potential Technology for Improving the Quality of Lake Water Environments in Cold Zones: A Case Study from Lake Hulun, China

Lakes in cold zones have common characteristics of long frozen periods and fragile water ecosystems. More and more lakes in cold zones have been experiencing water quality deterioration due to eutrophication with climate change and human activities. Lake Hulun is located in the cold zone of northern China, in which Cyanobacterial blooms frequently occur. The excessive nutrient input with inflowing river water and the change in lake hydrodynamic condition might be the main factors affecting this. To obtain a better understanding of the effects, the input loads of nutrients from the inflowing rivers were analyzed. A field test of freezing concentration combined with microbial activity regulation was carried out at a river–lake confluence. The results showed the following: (1) Lake Hulun receives a large amount of nitrogen and phosphorus pollutants from river runoff every year, and the water quality of these river is inferior Grade V, which greatly increases the difficulty in ecological purification of cold zone lakes. (2) The microbial activity control technology has a high purification rate for water during the unfrozen period. The order of purification rates for each hydrochemical index was TP > TN > COD > NH4+-N, and the purification rates of TN and COD were between 35% and 36%. Compared with the water before purification, the water quality grade improved from Grade V to Grade III. (3) The composite technology of freezing concentration–microbial activity regulation has a general water purification rate during the frozen period. Under the low-temperature condition, the TN and COD nutrient fluxes in the water were reduced by 9.38% and 9.36%, respectively. After purification, the water quality grade of the ice body was above Grade II, and the water under the ice layer was above Grade IV, which was one grade higher than the water quality grade of the original lake water. This water treatment and purification process is a green, low-energy consumption, and low-cost technology. This study can provide reference for the integration and demonstration of lake water ecological governance and water resources security technology in cold and arid regions. It is beneficial to the sustainable development of the lake.

Groundwater-Driven Evolution of Prebiotic Alkaline Lake Environments

Alkaline lakes are thought to have facilitated prebiotic synthesis reactions on the early Earth because their modern analogs accumulate vital chemical feedstocks such as phosphate through the evaporation of dilute groundwaters. Yet, the conditions required for some building block synthesis reactions are distinct from others, and these conditions are generally incompatible with those permissible for nascent cellular function. However, because current scenarios for prebiotic synthesis have not taken account of the physical processes that drive the chemical evolution of alkaline lakes, the potential for the co-occurrence of both prebiotic synthesis and the origins and early evolution of life in prebiotic alkaline lake environments remains poorly constrained. Here, we investigate the dynamics of active, prebiotically relevant alkaline lakes using near-surface geophysics, aqueous geochemistry, and hydrogeologic modeling. Due to their small size, representative range of chemistry, and contrasting evaporation behavior, the investigated, neighboring Last Chance and Goodenough Lakes in British Columbia, Canada offer a uniquely tractable environment for investigating the dynamics of alkaline lake behavior. The results show that the required, extreme phosphate enrichments in alkaline lake waters demand geomorphologically-driven vulnerability to evaporation, while the resultant contrast between evaporated brines and inflowing groundwaters yields Rayleigh–Taylor instabilities and vigorous surface–subsurface cycling and mixing of lake and groundwaters. These results provide a quantitative basis to reconcile conflicting prebiotic requirements of UV light, salinity, metal concentration, and pH in alkaline lake environments. The complex physical and chemical processing inherent to prebiotic alkaline lake environments thus may have not only facilitated prebiotic reaction networks, but also provided habitable environments for the earliest evolution of life.

Hydrochemical characteristics and salinity formation mechanism of different water bodies in the southern Tibet, China.

Understanding the hydrochemical evolution of surface water and groundwater is crucial for protecting regional ecological environments. Currently, there are few quantitative studies on the relative contributions of different processes to salinity enrichment of water bodies. In this study, sixty-seven water samples were collected for chemical, and isotopic analysis, along with simulation calculations. The results reveal distinct hydrochemical types of river water, phreatic water, lake water and hot spring water in the investigated area are Ca-Mg-HCO3, Na-Ca-HCO3, Na-SO4-HCO3 and Na-HCO3, respectively. Average temperature and depth of geothermal water storage are 196℃ and 1338m, respectively. Average arsenic (As) content in hot spring water (298μg/L) higher than that in lake water (39.2μg/L), river water (9.59μg/L) and phreatic water (4.02μg/L). The ∑REEs content of river water in the study area is much higher than that of phreatic water and lake water. Result of δD and δ18O indicate that atmospheric precipitation is the source of recharge for all water bodies in the study area. Quantitative calculations indicate that evapo-concentration significantly enriches lake water salinity, contributing on average 90% of its salt content. In contrast, mineral dissolution contributes predominantly to the salinity of hot spring water (90.7%), phreatic water (65.8%), and river water (45.2%). Evapo-concentration emerges as the dominant mechanism for lake water salinity, while carbonate mineral dissolution primarily affects river water. Phreatic water and hot spring water are mainly controlled by the weathering and dissolution of silicate. The results can provide a theoretical basis for the study of the formation mechanism of water salinity in other regions with similar geological environment in the world.

PH‐Directed Capture‐SELEX for Nanomolar Affinity Aptamers for Kanamycin Detection

Kanamycin A is a widely used antibiotic, although it has a narrow therapeutic window demanding highly accurate monitoring. The sensing of kanamycin A using aptamers is of great interest since aptamers can be used for continuous monitoring with a rapid response. While kanamycin has been the target for at least four previous aptamer selections, the binding affinities of the reported DNA aptamers are still sub‐optimal. All the previous aptamer selections were performed at pH 7.5 or higher. Given that kanamycin A has four amino groups with pKa values close to 7, we herein selected DNA aptamers for kanamycin A at both pH 6 and pH 8. The selection at pH 6 enriched aptamers although the pH 8 selection library remained highly diverse in the end. The best aptamer named KAN6‐1 showed a dissociation constant of around 320 nM measured using isothermal titration calorimetry in the selection buffer. In buffers without salt, binding can happen from pH 6 to 8. Specific binding was confirmed using mutation studies. A strand displacement assay was developed with a limit of detection (LOD) of 100 nM in buffer. Similar LOD values were also obtained in lake water and in 10% human serum. Comparisons were also made with some previously reported DNA aptamers. This study shows the importance of pH value on the selection of aptamers and provides a new aptamer for kanamycin A detection.

The perennially ice-covered Lake Enigma, Antarctica supports unique microbial communities

Northern Foothills of Victoria Land, Antarctica contains numerous hydrological formations, ranging from small surface streams and ponds fed by glacial or snow meltwater to permafrost lakes containing briny pockets. Here we describe the discovery of a massive body of unfrozen stratified oligotrophic water in Lake Enigma, a permanently ice-covered lake previously thought to be frozen from top to bottom. A remarkable feature of the Lake Enigma microbial ecosystem is the presence, and sometimes even dominance, of ultrasmall bacteria belonging to the superphylum Patescibacteria, a group apparently absent from Antarctic lakes in the well-studied McMurdo Dry Valleys. Cyanobacteria are virtually absent from Lake Enigma ice and water column although they are well represented in its extensive and diverse benthic microbial mats. Collectively, these features reveal a new complexity in Antarctic lake food webs and demonstrate that in addition to phototrophic and simple chemotrophic metabolisms, both symbiotic and predatory lifestyles may exist.

Drivers of Willingness to Pay in a National Water Conservancy Scenic Spot from a Perceived Value Perspective: A Case Study of Nanjing

This study considers Jinniu Lake (JNL), the biggest artificial lake and National Water Conservancy Scenic Spot (WCSS) in Nanjing, as an example to analyze the determinants of tourists’ willingness to pay (WTP) and satisfaction, as well as their pro-environmental behavior from a ‘tourist perceived value’ perspective (i.e., function, emotional, social, and epistemic), and then estimate the non-use value of JNL using the contingent valuation method (CVM). A total of 321 valid responses to questionnaires were analyzed using structural equation modeling (SEM) with the obtained results indicating the following: (1) JNL possesses a relatively high non-use value, influenced by emotional value, function value, social value, and epistemic value. (2) Satisfaction mediates the relationships between perceived value and WTP. (3) Education level, monthly travel frequency, and past visit frequency are all significantly positively correlated with WTP. In conclusion, strengthening tourists’ emotional and functional identification within destinations is conducive to improving visitor satisfaction and inspiring their pro-environmental behavior, ultimately feeding back into the development of the scenic area through WTP, achieving imitable ecological–economic circular development.

Environmental Exposure to Per- and Polyfluorylalkyl Substances (PFASs) and Reproductive Outcomes in the General Population: A Systematic Review of Epidemiological Studies

This Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) systematic review synthesized effects of background levels of per- and polyfluorylalkyl substance (PFAS) levels on reproductive health outcomes in the general public: fertility, preterm birth, miscarriage, ovarian health, menstruation, menopause, sperm health, and in utero fetal growth. The inclusion criteria included original research (or primary) studies, human subjects, and investigation of outcomes of interest following non-occupational exposures. It drew from four databases (Web of Science, PubMed, Embase and Health and Environmental Research Online (HERO)) using a standardized search string for all studies published between 1 January 2017 and 13 April 2022. Risk of bias was assessed by two independent reviewers. Data were extracted and reviewed by multiple reviewers. Each study was summarized under its outcome in terms of methodology and results and placed in context, with recommendations for future research. Of 1712 records identified, 30 were eligible, with a total of 27,901 participants (33 datasets, as three studies included multiple outcomes). There was no effect of background levels of PFAS on fertility. There were weakly to moderately increased odds of preterm birth with higher perfluorooctane sulfonic acid (PFOS) levels; the same for miscarriage with perfluorooctanoic acid (PFOA) levels. There was limited yet suggestive evidence for a link between PFAS and early menopause and primary ovarian insufficiency; menstrual cycle characteristics were inconsistent. PFAS moderately increased odds of PCOS- and endometriosis-related infertility, respectively. Sperm motility and DNA health were moderately impaired by multiple PFAS. Fetal growth findings were inconsistent. This review may be used to inform forthcoming drinking water standards and policy initiatives regarding PFAS compounds and drinking water. Future reviews would benefit from more recent studies. Larger studies in these areas are warranted. Future studies should plan large cohorts and open access data availability to capture small effects and serve the public. Funding: Great Lakes Water Authority (Detroit, MI), the Erb Family Foundation through Healthy Urban Waters at Wayne State University (Detroit, MI), and Wayne State University CLEAR Superfund Research (NIH P42ES030991).

Current source and migration of polychlorinated biphenyls (PCBs) since the ban: Bridging field data gap of 209 congeners in China’s 23 large lakes

Polychlorinated biphenyls (PCBs) were continuously receiving attention after their ban for use and production, owing to significant persistence, transport, and toxicity at trace level. Due to the field data gap of all 209 PCB congeners in previous studies, the source and environmental migration of lacustrine PCBs were not comprehensively understood. In this study, 209 PCB congeners in 277 water and 155 sediment samples collected from China’s 23 large lakes across a longitudinal transect (18–45 °N) were analyzed. Results showed that the concentrations of Σ209PCBs were 0.03–41.04 ng/L and 0.26–163.82 ng/g dry weight in lake water and sediment, respectively. In lake water, the dominant PCB congeners, detected in over 50% of all samples, were PCB 11, PCB 28+31, PCB 41+64+68, PCB 47+48+75, and PCB 51, with contributions to Σ209PCBs as 39.8%, 6.6%, 3.5%, 18.4%, and 6.4%, respectively. Source apportionment revealed that major contributions of PCB 11, 41+64+68, 47+48+75, 51, and 209, were mainly from unintentionally produced PCBs (UP-PCBs) while PCB 28+31 and the other congeners from historical PCB commercials. Therefore, the selective congener analysis (excluding UP-PCBs) common in previous lake studies was an omission. Simultaneously, the longitudinal fractionation of PCBs was also found in lake waters, likely caused by the East Asian monsoon. Moreover, fugacity fractions of PCBs between water and sediment indicated their overall equilibrium or net sorption. Overall, PCB 28+31 can be well indicative of PCB migration. This study provides basic information for the migration and transformation of trace toxic persistent organic pollutants.