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The Tibetan Plateau works as an important environmental and ecological barrier for the Asian continent. The researches on Tibetan environment and ecology are becoming extensive, but there is no systematic summary of research hotspots and trends in this field. Here, we analyzed 9180 publications retrieved from the WOS and CNKI during 2000 ~ 2020. The characteristics of publication, keywords with a 5-year interval and co-occurrence analysis were carried out so as to reveal the evolution and development trends of topics. The results show that articles increase dramatically since 2012. Except for common concerns like evolution, climate change, and precipitation, diversity was been studied more by Chinese scholars, while the USA, Germany, UK, and Australia researchers focused more on adaptability, basin western Tibet, lake, barley, and ore-related themes, respectively. Besides, China closely collaborated with the USA, Australia, and Germany in topics of evolution, climate change and degradation, precipitation, and diversity. The institutions located in Chinese different economic regions focused on different research keywords, such as vegetation, growth, trace elements, and geochemistry. The CAS contributed the most articles with 4254, showed advantages both in quantity and quality. Few articles were published by researchers affiliated to Free University of Berlin but with higher citations. It is the only one institute outside of China in the top 20. Main research hotspots include climate change, geology, and diversity. In future researches, ecological management and rehabilitation of mining area and tailings ponds, waste disposal, and changes of soil and water quality are worthy of attention and funding., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In Chinese freshwater lakes, eutrophication often coincides with heavy metal/metalloids (HM/Ms) pollution, yet the coevolution of critical nutrients (P, S, Se) and HM/Ms (Cd, Hg, etc.) remains understudied. To address this gap, we conducted a sedimentary chemistry analysis on a 30 cm-deep core, dating back approximately 200 years, retrieved from Chaohu Lake, China. The age-depth model revealed a gradual increase in deposition rates over time. Notably, the concentrations and enrichment factors (EFs) of most target elements surged in the uppermost ~ 15 cm layer, covering the period from 1953 to 2013, while both the concentrations and EFs in deeper layers remained relatively stable, except for Hg. This trend indicates a significant co-enrichment and near-synchronous increase in the levels and EFs of both nutrients and HM/Ms in the upper sediment layers since the mid-twentieth century. Anthropogenic factors were identified as the primary drivers of the enrichment of P, Se, Cd, Hg, Zn, and Te in the upper core, with their contributions also showing a coupled evolutionary trend over time. Conversely, geological activities governed the enrichment of elements in the lower half of the core. The gradual accumulation of anthropogenic Hg between the - 30 to - 15 cm layers might be attributed to global Hg deposition resulting from the industrial revolution. The ecological risk index (RI) associated with HM/Ms loading has escalated rapidly over the past 50 years, with Cd and Hg posing the greatest threats. Furthermore, the PMF model was applied to specifically quantify source contributions of these elements in the core, with anthropogenic and geogenic factors accounting for ~ 60 and ~ 40%, respectively. A good correlation (r 2  = 0.87, p < 0.01) between the PMF and Ti-normalized method was observed, indicating their feasibility and cross-validation in source apportionment. Finally, we highlighted environment impact and health implications of the co-enrichment of nutrients and HM/Ms. This knowledge is crucial for developing strategies to protect freshwater ecosystems from the combined impacts of eutrophication and HM/Ms pollution, thereby promoting water environment and human health., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Antioxidants are ubiquitous in various environmental samples, leading to increasing concern regarding their potential risk to environments or humans. However, there is dearth of information regarding the environmental fate of antioxidants and unknown/unexpected antioxidants in the environment. Here, we established a compound database (CDB) containing 320 current-used antioxidants by collecting the chemicals from EPA's functional use database and published documents. Physical-chemical characteristics of these antioxidants were estimated, and 19 ones were considered as persistent and bioaccumulative (P&B) substances. This CDB was further coupled with high resolution mass spectrometry (HRMS) technique, which was employed for suspect screening of antioxidants in extracts of sediments (n = 88) collected from Taihu Lake basin. We screened 119 HRMS features that can match 135 chemical formulas in the CDB, and 20 out of them exhibited the detection frequencies ≥ 90%. The total concentrations of suspect antioxidants in sediments ranged from 6.41 to 830 ng/g dw. Statistical analysis demonstrated that concentrations of suspect antioxidants in Taihu Lake were statistically significantly lower than those in Shihu and Jiulihu Lake, but greater than those from other small lakes. Collectively, this study provided a CDB that could be helpful for further monitoring studies of antioxidant in the environments, and also provided the first evidence regarding the ubiquity of antioxidants in aquatic environment of Taihu Lake basin., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

As the second deepest lake in Africa, Lake Tanganyika plays an important role in supplying fish protein for the catchment's residents and is irreplaceable in global biodiversity. However, the lake's water environment is threatened by socioeconomic development and rapid population growth along the lake. This study analyzed the spatial scale effects and seasonal dependence of land use types and landscape metrics on water quality in 16 sub-basins along northeastern Lake Tanganyika at different levels of urbanization. The results revealed that land use types had a higher influence on water quality in urban areas than that in rural areas; the explanatory variance in the urban area was 0.78-0.96, while it was 0.21-0.70 in the rural area. The explanatory ability of land use types on water quality was better at the buffer scale than at the sub-watershed scale, and the 500 m buffer scale had the highest explanatory ability in the urban area and rural area both in the rainy season and dry season, and artificial surface and arable land were the main contributing factors. And this phenomenon was more obvious in dry season than in rainy season. We identified that CONTAG was the key landscape metric in urban area and was positively correlated with nutrient variables, indicating that water quality degraded in less fragmented landscapes. The sub-watershed scale had the highest explained ability, while in rural area, the 1500 m buffer scale had the highest explained ability and IJI had the highest explanatory variance, which had a negative effect on water quality. Research on the relationship between land use and water quality would help assess the water quality in the unmonitored watershed as monitoring is expensive and time-consuming in low-income area. This knowledge would provide guideline to watershed managers and policymakers to prioritize the future land use development within Lake Tanganyika basin., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Organic matter (OM) and nutrient inputs generated by human activities promote the development of eutrophication. Amino acids (AAs) are an integral part of OM, and studying their patterns will provide new insights into organic matter dynamics in lakes. Four seasonal field campaigns in eutrophic Lake Taihu and a 14-day phytoplankton degradation experiment were carried out to determine the variability and bioavailability of amino acids. The quality and quantity of AAs varied among different seasons and lake types. The concentrations of particulate (PAA) and dissolved (DAA) AA were 14.67 ± 13.25 μM (carbon- and nitrogen-normalized PAA yields: PAA-C%, 23.8 ± 13.5%; PAA-N%, 22.8 ± 2.1%) and 2.95 ± 1.05 μM (carbon- and nitrogen-normalized DAA yields: DAA-C%, 3.7 ± 1.1%; DAA-N%, 12.6 ± 11.2%) in Lake Taihu, respectively. PAA and DAA showed high mean values in the algal-dominated northern area in summer. Glutamic acid (Glu), alanine (Ala), aspartic acid (Asp) and glycine (Gly) contributed to nearly 50% of PAA, while Gly, accounting for 17-24%, was the main component of DAA. During a 14-day phytoplankton degradation period, 98% of Chl a, 63% of POC and 92% of PAA were removed in the dark treatment, and a more obvious downward trend was recorded than in the light treatment. Principal component analysis of the indices of PAA indicated that Glu, arginine (Arg) and histidine (His) were dominant on day 0, while Gly and lysine (Lys) were dominant on day 14. There were notable serine + threonine (Ser + Thr [mol%]) and aspartic acid/glycine ratio (Asp/Gly [mol%]) end-member divisions among different organic matter sources. DAA had higher Ser + Thr [mol%] and lower Asp/Gly [mol%] values than PAA. The amino acid degradation index (DI) of PAA and DAA was 0.97 ± 0.28 and - 1.04 ± 0.43, respectively. The fresh DAA from the algae degradation incubation also had DI values similar to those of field DAA in the northern algae-dominated lake region. Amino acid parameters (AA-C%, DI values, Ser + Thr [mol%] and Asp/Gly [mol%]) were calculated to indicate the source, freshness and bioavailability of organic matter in eutrophic shallow Lake Taihu., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Understanding the historical variations in organic matter (OM) input to lake sediments and the possible mechanisms regulating this phenomenon is important for studying carbon cycling and burial in lake systems; however, this topic remains poorly addressed for macrophyte-dominated lakes. To bridge these gaps, we analyzed bulk OM and molecular geochemical proxies in a dated sediment core from Lake Liangzi, a typical submerged macrophyte-dominated lake in East China, to infer changes in OM input to sediments over the past 169 years due to the intensification of human activities in the catchment. A relatively primitive OM input pattern was observed in ca. 1841-1965, during which the lowest hydrogen index (HI), short-chain n-alkane abundance, and n-C 17 /n-C 16 alkane indicated minimal input from phytoplankton, whereas the high Paq (proxy of aquatic macrophyte input) and long-chain n-alkane abundance suggested dominant and subordinate inputs from submerged and emergent macrophytes, respectively. OM input transitioned during ca. 1965-1993, with the highest Paq and lowest long-chain n-alkane abundance, indicating an increase of submerged macrophyte input and concurrent decline of emergent macrophyte input, probably caused by hydrological regulation practices and land reclamation in the 1960s, respectively. A further shift in OM input was observed since ca. 1993, characterized by the beginning of an increase in phytoplankton input, as indicated by the greater HI, short-chain n-alkane abundance, and n-C 17 /n-C 16 alkane in sediments. Moreover, a lower Paq and higher abundance of long-chain n-alkanes indicated a decline in input from submerged macrophytes and an elevated input from terrestrial plants. The increase in αβ-hopane abundance and homohopane index value indicated that petroleum-sourced OM was first introduced into the sediments. The causes of these OM input changes included nutrient influx associated with domestic and industrial discharge, aquaculture within the lake, and widespread deforestation and land clearance in the catchment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Selenium (Se) deficiency is a major global health issue. Given that the Dongting Lake region is a significant agricultural production area in China, its soil and geographical properties have a marked influence on Se accumulation in rice. Investigating these factors and their importance can provide technical guidance for the production of Se-rich rice locally and in other similar regions worldwide. Such studies can foster Se-enriched agricultural practices on a global scale, contributing to improved human health and environmental quality. Therefore, in this study, we investigated 15,403 paddy soil samples and their corresponding rice grains from the Dongting Lake area, by analyzing their Se content, spatial distribution, and bioaccumulation factor (BCF). The effects of parent materials, soil characteristics (physicochemical), and geographical factors on Se content in soil, rice grains, and BCF were also assessed. We found that the average Se content in the paddy soil of the Dongting Lake area was 0.43 mg/kg, which was 1.48 folds higher than the background Se content (0.29 mg/kg) in Chinese soil. The average Se content in rice grains was 0.059 mg/kg, surpassing the Chinese standard for Se-rich rice (0.04 mg/kg). Se distribution in the paddy soil and rice were the highest in the western and central regions and lowest in the eastern region. Se-enriched rice and Se-enriched rice fields are widely distributed in Dongting Lake area. Seven parent materials significantly influenced soil Se and BCF. Correlation analysis revealed positive correlations between soil Se and soil organic matter (SOM), zinc, altitude, and mean annual precipitation. BCF was positively correlated with pH and mean annual temperature. The Random Forest model highlighted that SOM played a pivotal role in soil Se enrichment, being the most influential factor for both soil and rice enrichment (RR type), whereas pH exerted the most significant influence on soil enrichment without rice enrichment (RN type)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Viruses play a crucial role in aquatic ecosystems by regulating microbial composition and impacting biogeochemical cycling. While the response of viral diversity to the trophic status has been preliminarily explored in lake ecosystems, there is limited integrated exploration of the biogeography of viruses, host associations, and the auxiliary metabolic genes (AMGs), particularly for plateau lakes. Therefore, this research investigated the viral biogeography, virus-host association, and AMGs in the surface waters of 11 lakes varying in trophic levels (eutrophic and oligo-mesotrophic) in the Yunnan-Guizhou plateau region of China. A total of 73,105 viral operational taxonomic units were obtained from 11 samples, with 84.8 % remaining unannotated at the family level, indicating a predominance of novel viruses within these lakes. The most abundant viral family was Kyanoviridae (24.4 %), recognized as a common cyanophage. The vast majority of cyanobacteria and several eukaryotic algae were predicted as hosts for the viruses, with a lytic lifestyle predominating the life strategy of these cyanophages, implying the potential influence of the virus on algae. The viral community structure significantly correlated with both trophic status and the bacterial community. The structure equation model analysis revealed chlorophyll a was the primary factor affecting viral communities. Moreover, numerous AMGs linked to carbon metabolism, phosphorus metabolism, sulfur metabolism, and photosynthesis were found in these lakes, some of which showed virus preference for the trophic statuses, suggesting a vital role of the virus in driving biogeochemical cycling in the lake crossing different nutrient levels. In addition, a restricted presence of viruses was found to infect humans or harbor antibiotic resistance genes in the lakes, suggesting a subtle yet potential link to human health. Overall, these findings offer insights into the response of viral communities to eutrophication and their potential role in biogeochemical cycling and controlling algal propagation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Emergence and spread of antibiotic resistance genes (ARGs) in lakes have been considered as a global health threat. However, a thorough understanding of the distribution patterns and ecological processes that shape the ARGs profile in interconnected river-lake systems remains largely unexplored. In this study, we collected paired water and sediment samples from a typical interconnected river-lake system, Dongting Lake in China, during both wet and dry seasons. Using high-throughput quantitative PCR, we investigated the spatial and temporal distribution of ARGs and the factors that influence them. A total of 8 major antibiotic classes and 10 mobile genetic elements were detected across the Dongting Lake basin. The unique hydrological characteristics of this interconnected river-lake system result in a relatively stable abundance of ARGs across different seasons and interfaces. During the wet season, deterministic processes dominated the assembly of ARGs, allowing environmental factors, such as heavy metals, to serve as main driving forces of ARGs distribution. When the dry season arrived, variations in hydrological conditions and changes in ARGs sources caused stochastic processes to dominate the assembly of ARGs. Our findings provide valuable insights for understanding the ecological processes of ARGs in interconnected river-lake systems, emphasizing the necessity of upstream restoration and clarifying river-lake relationships to mitigate ARGs dissemination., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Climate and human activity are two important factors in regulating organic matter (OM) accumulation in the lake environment. However, when and how anthropogenic impacts have affected lacustrine OM accumulation in southwest China during the late Holocene have not yet been well defined. Here, a 16.3-kyr n-alkane record derived from Erhai Lake was used to trace OM sources and explore their connections to climate and human activity. The n-alkane distributions indicated that the dominant sediment sources shifted from terrestrial and aquatic plants to algae in the late Holocene. OM accumulation was closely related to catchment soil erosion, sediment transport, and deposition processes regulated by climate conditions before 5.0 cal. kyr B.P., following the patterns that stronger monsoon precipitation favoured more terrestrial and less aquatic OM input, and vice versa. From 5.0 to 2.0 cal. kyr B.P., the synchronous downwards trends in terrestrial OM input and precipitation intensity indicated that climate remained a major driving force for OM accumulation. However, sediment sources experienced large-magnitude and centennial-scale oscillations between allochthonous and autochthonous inputs, reflecting early human impacts appeared and lake ecosystems retained the self-regulated ability to recover from the basin-wide early moderate human disturbances. Afterwards, the increased (decreased) OM contributions from terrestrial (aquatic) plants contradicted the weakening monsoon precipitation since 2.0 cal. kyr B.P., indicating a dominant effect of human activities on OM accumulation. This change was accompanied by highly improved algae productivity and gradually elevated lacustrine trophic status, and the lake ecosystem eventually shifted into another state largely deviating from its climate-driven background due to intensified deforestation and agricultural cultivation. Regional comparison indicated that anthropogenic disturbances have temporal differences in southwest China. This study will further improve our understanding of past climate-human-environment interactions in southwest China., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The impact of the Coronavirus Disease 2019 (COVID-19) pandemic on microplastic (MP) occurrence in aquatic environments deserves an in-depth study. In this study, the occurrence of MPs and environmental flux of plastics before (2019) and during (2020 and 2021) the pandemic were comparatively investigated in various aquatic compartments in the Taihu Lake Basin in China. The field-based investigations from 2019 to 2021 for Taihu Lake have shown that, at the onset of the outbreak, the MP abundance declined at a rate of 62.3 %, but gradually recovered to the pre-pandemic level. However, the amount of plastics being released into aquatic environments showed a declining trend in 2020 and 2021 compared to those in 2019, with decrease rates of 13.7 % and 15.8 %, respectively. Characterization analysis of MP particles and source apportionment framework implied that while the contributions of tire abrasion and domestic waste to MP occurrence were depleted owing to the reduction in human activity during the pandemic, weathering and fragmentation of retained plastics contributed to the recovery of stored MPs. This study provides insights into the anthropogenic influences on MP occurrence, and supports policymakers in managing and controlling plastic contamination in large freshwater systems in the "new normal" phase., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In order to clarify the nitrogen (N) and phosphorus (P) regeneration patterns and internal mechanism for initiating and maintaining algal blooms in Lake Taihu, samples (including surface water and sediment) from 8 sites in Lake Taihu were collected for nine times from May 2010 to April 2011, and analyzed for total and labile organic matter, P fractionation and sorption behaviors, extracellular enzymatic activities (EEA), dehydrogenase activity, the respiratory electron transport system activity, and iron in sediment, EEA, N and P species and chlorophyll a (Chl. a) in surface water, as well as N and P species in interstitial water. In Lake Taihu, although severe blooms occurred in both Meiliang Bay and Zhushan Bay, the nutrient regeneration patterns stimulating the initiation and maintenance of algae blooms in these two bays were different. In Zhushan Bay with low EEA in surface water, abundant N and P flux from sediments, due to the degradation of organic matter and enzymatic hydrolysis in sediment, further stimulated the initiation and maintenance of algae blooms. In Meiliang Bay, in spite of lower nutrient supply from sediment, high EEA in surface water occurred later than the serious blooms, showing that the nutrient regeneration from sediment, not water body, was still the trigger for the start of the bloom, and sediment nutrient release and predominant surface water nutrient regeneration by abundant exoenzymes sustained the algal blooms. In the Western region, algal bloom started in the northern area and further spread in the remaining part of the lake; nutrient regeneration in the surface water sustained the slight bloom. In the East Bays, the decay and decomposition of macrophytes led to anaerobic conditions in sediments and high ammonia in interstitial water, but low iron bound phosphorus resulted in anaerobic release of very few P, thus showed extremely low Chl. a concentration., Competing Interests: Declaration of competing interest We declare that we have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Land Use/ Cover Change (LUCC) plays a crucial role in influencing hydrological processes, nutrient cycling, and sediment transport in watersheds, ultimately impacting water quality on both spatial and temporal scales. Accurately predicting changes in watershed water quality is beneficial for the sustainable management of water resources. Current models often lack the ability to effectively predict water quality changes in a dynamic spatio-temporal context, particularly in complex watershed environments. The overall purpose of the study is to establish a comprehensive and dynamic modeling framework that links LUCC with water quality, allowing for accurate predictions of future water quality under varying land use scenarios. The model, which uses water quality as the dependent variable and LUCC as the independent variable, was developed to quantitatively predict changes in watershed water quality. To achieve this, annual multi-period remote sensing images from Landsat-5, Landsat-8 or Sentinel-2 satellites spanning from 1992 to 2022 were analyzed. Random Forest (achieving a Kappa coefficient of 0.9468) were employed to classify land use within the watershed. Based on classification results, a Cellular Automata-Markov chain model (CA-Markov) was constructed to simulate and predict the spatio-temporal patterns of land use, incorporating driving factors such as proximity to water systems, roads, elevation, and slope. Validation of the model using LUCC data from 2020 yielded a high prediction accuracy with a Kappa coefficient of 0.9505. The CA-Markov model was further utilized to project LUCC under three different scenarios-natural development, ecological protection, and arable land protection-between 2023 and 2033. Based on these projections, the coupled water quality and LUCC model was employed to predict water quality changes in the watershed over the same period. Key findings indicate that water quality is likely to improve under ecological protection scenario, while deterioration is expected under natural development scenario and cropland protection scenario due to urban expansion, agricultural practices, and water diversion for irrigation. This study provides a robust framework for watershed management, offering scientific guidance for source management and water purification efforts, thereby contributing significantly to the sustainable development of water resources., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Xiaoming Li reports financial support was provided by China Hunan Provincial Science and Technology Department. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Anthropogenic activities have significantly enriched P in sediments of many water bodies, with redox potential (Eh) being a key factor in controlling P adsorption or release.This study evaluates the impact of Eh on P release from sediments in the Weiyuan River, Honghu Lake, and Bao'enqiao Reservoir using reactor experiments. P speciation was further analyzed through SEDEX method. Results show that within an Eh range of -300 mV to +230 mV, more P is released from sediments into the water column. The P fractions CDB-P and Fe(II)-P exhibit the most significant changes, especially in reservoir sediments where ΔCDB-P (85.5 mg/kg) and ΔFe(II)-P (80.6 mg/kg) are the highest among the three water bodies, followed by lake sediments. Additionally, after redox oscillation, the EPC 0 of lake and reservoir sediments increased to 16.2 and 18.8 times their initial values, respectively, significantly raising the risk of eutrophication., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Ice, water, and sediment represent three interconnected habitats in lake ecosystems, and bacteria are crucial for maintaining ecosystem equilibrium and elemental cycling across these habitats. However, the differential characteristics and driving mechanisms of bacterial community structures in the ice, water, and sediments of seasonally frozen lakes remain unclear. In this study, high-throughput sequencing technology was used to analyze and compare the structure, function, network characteristics, and assembly mechanisms of bacterial communities in the ice, water, and sediment of Wuliangsuhai, a typical cold region in Inner Mongolia. The results showed that the bacterial communities in the ice and water phases had similar diversity and composition, with Proteobacteria, Bacteroidota, Actinobacteria, Campilobacterota, and Cyanobacteria as dominant phyla. The bacterial communities in sediments displayed significant differences from ice and water, with Chloroflexi, Proteobacteria, Firmicutes, Desulfobacterota, and Acidobacteriota being the dominant phyla. Notably, the bacterial communities in water exhibited higher spatial variability in their distribution than those in ice and sediment. This study also revealed that during the frozen period, the bacterial community species in the ice, water, and sediment media were dominated by cooperative relationships. Community assembly was primarily influenced by stochastic processes, with dispersal limitation and drift identified as the two most significant factors within this process. However, heterogeneous selection also played a significant role in the community composition. Furthermore, functions related to nitrogen, phosphorus, sulfur, carbon, and hydrogen cycling vary among bacterial communities in ice, water, and sediment. These findings elucidate the intrinsic mechanisms driving variability in bacterial community structure and changes in water quality across different media phases (ice, water, and sediment) in cold-zone lakes during the freezing period, offering new insights for water environmental protection and ecological restoration efforts in such environments., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

To carry out the diagnosis and evaluation of the ecosystem health in Yuxi three-lake watershed, this paper presents the changing trend of its health state, and predicts the future development. This also provides ideas for maintaining the regional ecosystem health, and then gradually improves the ecological environment quality. Taking Fuxian Lake, Qilu Lake and Xingyun Lake (the three-lake watershed) in Yuxi City, Yunnan Province, Southwest China as the research object, a model combining pressure-state-response and kernel density estimation (PSR-KDE) adopts to diagnose and evaluate the ecosystem health of the "three lake" watershed from 2010 to 2020, and the distribution map of ecosystem health index has obtained by the evaluation indexes integration based on GIS spatial analysis. Hence, the evaluation results have visualized on the map. The results show that: The distribution of ecosystem health index in the study area was 0.1530-0.7045 in 2010, 0.2056-0.7512 in 2015, and 0.2248-0.7662 in 2020. 0.12% was in the pathological area in 2010. After 2015, the pathological condition of ecosystem health has completely solved, and the proportion of unhealthy ecosystems was 11.95% in 2010, 7.38% in 2015, and 5.97% in 2020. The ecosystem health index of the study region was 0.5523 in 2010, 0.5807 in 2015, and 0.5815 in 2020, it indicates that the ecosystem was in a sub-health state. From 2010 to 2020, the ecosystem health around Qilu Lake was the most worrying, followed by the northwest of Fuxian Lake and the northern and southern regions of Xingyun Lake. The ecosystem health of the three-lake watershed showed significant improvement from 2010 to 2020. The study ecosystem health assessment and early warning in the three-lake watershed is significant to the ecological environment protection and management of the plateau lake basin, the restoration of the territorial space ecology and the economic development of the surrounding area., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Understanding the relationship between suspended particulate matter (SPM), sediment organic C, N stable isotopes, and lake trophic state index (TSI) is essential for managing lake pollution and eutrophication. According to the δ 13 C, δ 15 N, and C/N we found that the organic C in SPM and sediment of Caohai Lake primarily originated from macrophytes, while N was sourced from chemical fertilizers, phytoplankton, and aquatic plants. Total nitrogen, total phosphorus, NO3 - -N, oxidation reduction potential, and Chl.a were identified as key factors influencing the sources and variations of SPM and sediment organic C and N stable isotopes in Caohai Lake, with a significant linear correlation observed between C, N stable isotopes, and TSI in sediments. To mitigate eutrophication in Caohai Lake, it is recommended that farmers apply fertilizers judiciously to minimize nutrient loss and that aquatic plants be regularly harvested to reduce N release from plant residues., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

As one of the nine primary non-ferrous metal smelting bases in China, Daye Lake basin was polluted due to diverse human activities. But so far the pollution status and related ecological risks of this region have not been detailly investigated. In current study, pollutants including heavy metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in eight sediment samples from Daye Lake were quantified. 18S rRNA gene sequencing was employed to profile the nematode community structure within these sediments. Model organism Caenorhabditis elegans (C. elegans) were further applied for a comprehensive ecological risk assessment of Daye Lake. Notably, Cadmium (Cd) was identified as a key driver of ecological risk, reaching an index of 1287.35. At sample point S4, OCPs particularly p,p'-DDT, displayed an extreme ecological risk with a value of 23.19. Cephalobidae and Mononchida showed strong sensitivity to pollutant levels, reinforcing their suitability as robust bioindicators. The composite pollutants in sampled sediments caused oxidative stress in C. elegans, with gene Vit-2 and Mtl-1 as sensitive biomarkers. By employing the multiple analysis methods, our data can offer valuable contributions to environmental monitoring and health risk assessment for composite polluted areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper and confirm the content of this manuscript has not been published in a refereed journal., (Copyright © 2024. Published by Elsevier B.V.)

Sediments are important heavy metal sinks in lakes, crucial for ensuring water environment safety. Existing studies mainly focused on well-studied lakes, leaving gaps in understanding pollution patterns in specific basins and influencing factors.We compiled comprehensive sediment contamination data from literature and public datasets, including hydro-geomorphological, climatic, soil, landscape, and anthropogenic factors. Using advanced machine learning, we analyzed typical pollution factors to infer potential sources and migration pathways of pollutants and predicted pollution levels in basins with limited data availability. Our analysis of pollutant distribution data revealed that Cd had the most extensive pollution range, with the most severe pollution occurring in the Huaihe and Yangtze River basins. Furthermore, we identified distinct groups of driving factors influencing various heavy metals. Cd, Cr, and Pb were primarily influenced by human activities, while Cu and Ni were affected by both anthropogenic and natural factors, and Zn tended more towards natural sources. Our predictions indicated that, in addition to the typical highly polluted areas, the potential risk of Cd, Cu and Ni is higher in Xinjiang, and in Tibet and Qinghai, the potential risk of Cd, Cr, Cu and Ni is higher. Pb and Zn presented lower risks, except in the Huaihe and Yangtze River Basins. Temperature, wind, precipitation, precipitation rate, and the cation exchange capacity of soil significantly impacted the predictions of heavy metal pollution in sediments, suggesting that particulate migration, rainfall runoff, and soil erosion are likely the main pathways for pollutant migration into sediments. Considering the migration, pathways, and sources of pollutants, we propose strategies such as low-impact development and promoting sustainable transportation to mitigate pollution. This study provides the latest insights into heavy metal pollution in Chinese lake sediments, offering references for policy-making and water resource management., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The Eastern Route of the South-to-North Water Diversion Project (ER-SNWDP) represents a crucial initiative aimed at alleviating water scarcity in China's northern region. Understanding the dynamics governing the composition and assembly processes of micro-eukaryotic communities within the canal during different water diversion periods holds paramount significance for the effective management of the ER-SNWDP. Our study systematically tracks the dynamics of the micro-eukaryotic community and its assembly processes along the 1045.4 km of canals and four impounded lakes, totaling 3455 km 2 , constituting the ER-SNWDP during a complete water diversion cycle, utilizing high-throughput sequencing, bioinformatics tools, and null modeling algorithms. The primary objectives of this study are to elucidate the spatial-temporal succession of micro-eukaryotic communities as the water diversion progresses, to delineate the relative importance of deterministic and stochastic processes in community assembly, and to identify the pivotal factors driving changes in micro-eukaryotic communities. Our findings indicate notable variations in the composition and diversity of micro-eukaryotic communities within the ER-SNWDP across different water diversion periods and geographic locations (P < 0.05). This variation is influenced by a confluence of temporal and environmental factors, with limited impacts from water diversion. In essence, the assembly of micro-eukaryotic communities within the ER-SNWDP primarily stemmed from heterogeneous selection driven by deterministic processes. Water diversion exhibited a tendency to decrease community beta diversity while augmenting the influence of stochastic processes in community assembly, albeit this effect attenuated over time. Furthermore, our analysis identified several pivotal environmental parameters, notably including nitrite-nitrogen, nitrate-nitrogen, orthophosphate, and water temperature, as exerting significant effects on micro-eukaryotic communities across different water diversion periods. Collectively, our study furnishes the inaugural comprehensive exploration of the dynamics, assembly processes, and influencing factors governing micro-eukaryotic communities within the ER-SNWDP, thus furnishing indispensable insights to inform the water quality management of this important project., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Microorganisms are crucial components of freshwater ecosystems. Understanding the microbial community assembly processes and niche characteristics in freshwater ecosystems, which are poorly understood, is crucial for evaluating microbial ecological roles. The Yunnan Plateau lakes in China represent a freshwater ecosystem that is experiencing eutrophication due to anthropogenic activities. Here, variation in the assembly and niche characteristics of both prokaryotic and microeukaryotic communities was explored in Yunnan Plateau lakes across two seasons (dry season and rainy season) to determine the impacts of rainfall and environmental conditions on the microbial community and niche. The results showed that the environmental heterogeneity of the lakes decreased in the rainy season compared to the dry season. The microbial (bacterial and microeukaryotic) α-diversity significantly decreased during the rainy season. Deterministic processes were found to dominate microbial community assembly in both seasons. β-Diversity decomposition analysis revealed that microbial community compositional dissimilarities were dominated by species replacement processes. The co-occurrence networks indicated reduced species complexity for microbes and a destabilized network for prokaryotes prior to rainfall, while the opposite was found for microeukaryotes following rainfall. Microbial niche breadth decreased significantly in the rainy season. In addition, lower prokaryotic niche overlap, but greater microeukaryotic niche overlap, was observed after rainfall. Rainfall and environmental conditions significantly affected the microbial community assembly and niche characteristics. It can be concluded that rainfall and external pollutant input during the seasonal transition alter the lake environment, thereby regulating the microbial community and niche in these lakes. Our findings offer new insight into microbiota assembly and niche patterns in plateau lakes, further deepening the understanding of freshwater ecosystem functioning., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Diazinon is an organophosphorus pesticide widely used in agriculture and household pest control, and its use also poses several environmental and health hazards. In this study, we investigated the spatial and temporal distribution of diazinon in Baiyangdian, evaluated its potential ecological risk and toxicity to aquatic organisms based on RQ (Risk quotient) and TU (Toxic unit) analysis, and assessed the potential effects of diazinon accumulation on probiotics and pathogens based on statistical analysis of high-throughput sequencing data. The results showed that diazinon in Baiyangdian posed a low to moderate chronic risk to sediment-dwelling organisms and a low toxicity effect on aquatic invertebrates, which was mainly concentrated in October and human-intensive areas. Meanwhile, increases in sediment electrical conductivity (EC), amorphous iron oxides content and phenol oxidase activity favored diazinon accumulation in sediments, whereas the opposite was the case for sediment organic carbon, β-1,4-glucosidase, phosphatase, catalase and pH, suggesting that environmental indicators play a key role in the behavior and distribution of diazinon. In addition, diazinon in heavily contaminated areas seem to inhibit the rare probiotics (Bifidobacterium adolescentis and Serratia sp.), while promoted dominant pathogens (e.g., Burkholderia cenocepacia), which can lead to increased disease risk to humans and ecosystems, disruption of ecological balance and potential health problems. However, probiotic Streptomyces xiamenensis resist to diazinon would be a potential degrader for diazinon remove. In conclusion, this study unveiled the effects of diazinon pollution on wetland ecosystems, emphasizing ecological impacts and potential health concerns. In addition, the discovery of diazinon resistant probiotics provided new insights into wetland ecological restoration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Lake Taihu, an inland lake, frequently experiences Cyanobacterial blooms that have historically posed severe threats to its aquatic ecosystem. Combining field observations and satellite remote-sensed data, factors that influence algal bloom intensity in Lake Taihu over an eight-year period, from 2016 to 2023, are examined, and changes in phytoplankton community composition, climate, water quality, economic activities, and food web dynamics are reported. Sentinel-2 MSI data analysis reveals a dramatic decrease in Cyanobacterial blooms in 2023, with a reduction in the annual maximum bloom area of 76.90 % from 2016 values. From 2016 to 2022, the ratio of Cyanobacteria to other phytoplankton ranged 82.09 %-98.29 %, but in 2023, this dropped to 60.98 %. Concurrently, Cyanobacteria density dropped to an historic low of 2.29 × 10 7 cells/L (16.4 % of 2021 peak values). Redundancy and random forest analyses indicated that nitrogen has a greater influence on phytoplankton than phosphorus, with temperature and permanganate index being the important parameters to affect phytoplankton community structure. We attribute the decrease in Cyanobacterial blooms in Lake Taihu in 2023 to be largely caused by shifts in phytoplankton community structure, particularly the sharp decline in Microcystis sp. density, a genus often linked to bloom formation. Meteorological conditions such as reduced rainfall and wind speed during the winter and spring of 2023 also contributed to diminishing Cyanobacterial blooms. Ongoing improvements in water quality, reduced economic activities because of pandemic restrictions, and implementation of a fishing ban since 2020 have likely further contributed to reductions in bloom frequency. These results improve our understanding of the processes that affect algal blooms in Lake Taihu, and potentially other eutrophic inland lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Currently, more and more lakes around the world are experiencing outbreaks of cyanobacterial blooms, and high-precision and rapid monitoring of the spatial distribution of algae in water bodies is an important task. Remote sensing technology is one of the effective means for monitoring algae in water bodies. Studies have shown that the Floating Algae Index (FAI) is superior to methods such as the Standardized Differential Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) in monitoring cyanobacterial blooms. However, compared to the NDVI method, the FAI method has difficulty in determining the threshold, and how to choose the threshold with the highest classification accuracy is challenging. In this study, FAI linear fitting model (FAI-L) is selected to solve the problem that FAI threshold is difficult to determine. Innovatively combine FAI index and NDVI index, and use NDVI index to find the threshold of FAI index. In order to analyze the applicability of FAI-L to extract cyanobacterial blooms, this paper selected multi-temporal Landsat8, HJ-1B, and Sentinel-2 remote sensing images as data sources, and took Chaohu Lake and Taihu Lake in China as research areas to extract cyanobacterial blooms. The results show that (1) the accuracy of extracting cyanobacterial bloom by FAI-L method is generally higher than that by NDVI and FAI. Under different data sources and different research areas, the average accuracy of extracting cyanobacterial blooms by FAI-L method is 95.13%, which is 6.98% and 18.43% higher than that by NDVI and FAI respectively. (2) The average accuracy of FAI-L method for extracting cyanobacterial blooms varies from 84.09 to 99.03%, with a standard deviation of 4.04, which is highly stable and applicable. (3) For simultaneous multi-source image data, the FAI-L method has the highest average accuracy in extracting cyanobacterial blooms, at 95.93%, which is 6.77% and 13.26% higher than NDVI and FAI methods, respectively. In this paper, it is found that FAI-L method shows high accuracy and stability in extracting cyanobacterial blooms, and it can extract the spatial distribution of cyanobacterial blooms well, which can provide a new method for monitoring cyanobacterial blooms., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Microplastics (MPs) are emerging as anthropogenic vectors to form plastisphere, facilitating microbiome colonization and pathogenic dissemination, thus contributing to environmental and health crises across various ecosystems. However, a knowledge gap persists regarding MPs risks and their driving factors in certain unique and vulnerable ecosystems, such as Karst travertine lakes, some of which are renowned World Natural Heritage Sites under ever-increasing tourism pressure. We hypothesized that tourism activities serve as the most important factor of MPs pollution, whereas intrinsic features, including travertine deposition can exacerbate potential environmental risks. Thus, metagenomic approaches were employed to investigate the geographical distribution of the microbiome, antibiotic resistance genes (ARGs), virulence factor genes (VFGs), and their combined environmental risks in Jiuzhaigou and Huanglong, two famous tourism destinations in Southwest China. The plastisphere risks were higher in Huanglong, contradicting our hypothesis that Jiuzhaigou would face more crucial antibiotic risks due to its higher tourist activities. Specifically, the levels of Lipopolysaccharide Lewis and fosD increased by sevenfold and 20-fold, respectively, from upstream to downstream in Huanglong, whereas in Jiuzhaigou, no significant accrual was observed. Structural equation modeling results showed that travertine deposition was the primary contributor to MPs risks in alpine karstic lakes. Our findings suggest that tourism has low impact on MPs risks, possibly because of proper management, and that travertine deposition might act as an MPs hotspot, emphasizing the importance of considering the unique aspects of travertine lakes in mitigating MPs pollution and promoting the sustainable development of World Natural Heritage Sites., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) have long been globally distributed, and almost worldwide people are exposed to varying degrees of PAHs. Aqueous medium is an important transmission route of PAHs, but the detection of PAHs in aqueous environment has been a challenge. Herein, a magnetic hypercrosslinked polymer microsphere (Fe 3 O 4 @SiO 2 -PS@HCP) was developed for the effective detection of PAHs. Under the effect of multiple factors (hydrophilicity, intermolecular force and molecular volume), Fe 3 O 4 @SiO 2 -PS@HCP shows excellent performance on the enrichment of five PAHs in aqueous environment. Fe 3 O 4 @SiO 2 -PS@HCP was used to capture PAHs in city river of plateau lake. In-depth data analysis showed that factory activities and traffic emissions are the main pollution sources of PAHs. Ecological, carcinogenic and non-carcinogenic risks are almost within the safe range. The carcinogenic and non-carcinogenic risks of PAHs in children are higher than adults, which needs to be taken seriously. This method breaks the dilemma that it is difficult to enrich weakly hydrophilic pollutants in aqueous media, and complements important pathways for tracing sources of pollutants and assessing associated risks. It brings methodological enlightenment into the development of environmental pollution and human health risk assessment methodology., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The proliferation of filamentous cyanobacteria in lakes can result in the generation of odor-causing compounds, predominantly 2-methylisoborneol (2-MIB), which pose odor-related challenges. In an effort to elucidate the spatiotemporal dynamics of 2-MIB and related influencing factors in East Lake Taihu, monthly investigations were undertaken from April 2022 to March 2023. In addition to the monthly survey, a whole-lake survey was conducted during the high-temperature period from July to September. The monthly survey revealed a distinct unimodal fluctuation in the concentration of 2-MIB in East Lake Taihu, with an average concentration at 297.0 ng/L during the high-temperature period. During the high-temperature period, the filamentous cyanobacterial communities detected in East Lake Taihu consisted primarily of species belonging to genera Leptolyngbya, Oscillatoria, Planktothricoides, and Pseudanabaena. However, no significant correlations were found between their densities and 2-MIB concentration. In addition, the mic gene was predominantly detected in genera Pseudanabaena and Planktothricoides, with the latter being the primary contributor to 2-MIB production. Furthermore, a succession of cyanobacteria capable of producing 2-MIB was detected, with water temperature and radiation intensity being identified as the primary driving factors. The temporal variation of 2-MIB concentration within East Lake Taihu during the whole year was primarily modulated by factors such as water temperature, water transparency, dissolved oxygen, and chlorophyll-a. During the high-temperature period, the 2-MIB concentration in the alga-dominated zone of East Lake Taihu was approximately 1.7 times greater than that in the macrophyte-dominated zone, with nutrient and transparency being identified as the main influencing factors. Consequently, our findings are of great significance for monitoring the sources and variation of 2-MIB in shallow lakes, providing a scientific foundation and theoretical guidance for odor management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

In recent years, the global carbon cycle has garnered significant research attention. However, details of the intricate relationship between planktonic bacteria, hydrochemistry, and dissolved organic matter (DOM) in inland waters remain unclear, especially their effects on lake carbon sequestration. In this study, we analyzed 16S rRNA, chromophoric dissolved organic matter (CDOM), and inorganic nutrients in Erhai Lake, Yunnan Province, China. The results revealed that allochthonous DOM (C3) significantly regulated the microbial community, and that autochthonous DOM, generated via microbial mineralization (C2), was not preferred as a food source by lake bacteria, and neither was allochthonous DOM after microbial mineralization (C4). Specifically, the correlation between the fluorescence index and functional genes (FAPRPTAX) showed that the degree of utilization of DOM was a critical factor in regulating planktonic bacteria associated with the carbon cycle. Further examination of the correlation between environmental factors and planktonic bacteria revealed that Ca 2+ had a regulatory influence on the community structure of planktonic bacteria, particularly those linked to the carbon cycle. Consequently, the utilization strategy of DOM by planktonic bacteria was also determined by elevated Ca 2+ levels. This in turn influenced the development of specific recalcitrant autochthonous DOM within the high Ca 2+ environment of Erhai Lake. These findings are significant for the exploration of the stability of DOM within karst aquatic ecosystems, offering a new perspective for the investigation of terrestrial carbon sinks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The river-connected Dongting Lake (DT) and Poyang Lake (PY), and the gate-controlled Taihu Lake (TH) and Chaohu Lake (CH) are the four important lakes in the Yangtze River Basin. The comprehensive Water Quality Index (WQI), the Eutrophication Integrated Index (TLI(Σ)), and the Positive Matrix Factorization (PMF) model were employed to evaluate water quality and the contribution of pollution sources for these lakes. The results show that WQI for all lakes indicated generally good water quality, with DT scoring 73.52-86.18, the highest among them. During the wet season, the eutrophication degree of river-connected lake was medium, and that of gate-controlled lakes was high. The surface runoff and agricultural non-point sources are the main pollution sources for both types of lakes, but their impact is more pronounced in gate-controlled lakes during the wet season. The study provides evidence support for scientific understanding of water quality problems and management strategies in these areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Phytoplankton communities are crucial components of aquatic ecosystems, and since they are highly interactive, they always form complex networks. Yet, our understanding of how interactive phytoplankton networks vary through time under changing environmental conditions is limited. Using a 29-year (339 months) long-term dataset on Lake Taihu, China, we constructed a temporal network comprising monthly sub-networks using "extended Local Similarity Analysis" and assessed how eutrophication, climate change, and restoration efforts influenced the temporal dynamics of network complexity and stability. The network architecture of phytoplankton showed strong dynamic changes with varying environments. Our results revealed cascading effects of eutrophication and climate change on phytoplankton network stability via changes in network complexity. The network stability of phytoplankton increased with average degree, modularity, and nestedness and decreased with connectance. Eutrophication (increasing nitrogen) stabilized the phytoplankton network, mainly by increasing its average degree, while climate change, i.e., warming and decreasing wind speed enhanced its stability by increasing the cohesion of phytoplankton communities directly and by decreasing the connectance of network indirectly. A remarkable shift and a major decrease in the temporal dynamics of phytoplankton network complexity (average degree, nestedness) and stability (robustness, persistence) were detected after 2007 when numerous eutrophication mitigation efforts (not all successful) were implemented, leading to simplified phytoplankton networks and reduced stability. Our findings provide new insights into the organization of phytoplankton networks under eutrophication (or re-oligotrophication) and climate change in subtropical shallow lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

To clarify the wind-driven post-bloom dispersion range of Microcystis, which originally clustered on the water surface, an Individual-Based Model (IBM) of Microcystis movement considering the combined effects of wind and light was developed based on actual hydrodynamic data and Microcystis biomass. After calibrating the effects of hydrodynamics and light, 66 cases of short-term (within a week) post-bloom with satellite images from 2011 to 2017 were simulated. The results showed that there were three short-term post-bloom types: vertical reduction (VR), horizontal reduction (HR) and mixed reduction (MR). For VR type, the cyanobacterial bloom reduction rate was rapid (>160 km 2 /day), but the dispersion range of Microcystis was limited (<2 km/day), and a larger bloom area was likely to form in the original location when wind speed decreased. For HR type, the cyanobacterial bloom reduction rate was slow (<10 km 2 /day), but Microcystis exhibited a broad dispersion range (>4 km/day), often leading to smaller, thicker, and longer-lasting cyanobacterial blooms downwind, albeit with a lower probability of occurrence. The characteristics of MR lay between the two aforementioned types., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Depletion of dissolved oxygen (DO) is a significant incentive for biological catastrophic events in freshwater lakes. Although predicting the DO concentrations in lakes with high-frequency real-time data to prevent hypoxic events is effective, few related experimental studies were made. In this study, a short-term predicting model was developed for DO concentrations in three problematic areas in China's Chaohu Lake. To predict the DO concentrations at these representative sites, which coincide with biological abnormal death areas, water quality indicators at the three sampling sites and hydrometeorological features were adopted as input variables. The monitoring data were collected every 4 h between 2020 and 2023 and applied separately to train and test the model at a ratio of 8:2. A new AC-BiLSTM coupling model of the convolution neural network (CNN) and the bidirectional long short-term memory (BiLSTM) with the attention mechanism (AM) was proposed to tackle characteristics of discontinuous dynamic change of DO concentrations in long time series. Compared with the BiLSTM and CNN-BiLSTM models, the AC-BiLSTM showed better performance in the evaluation criteria of MSE, MAE, and R 2 and a stronger ability to capture global dependency relationships. Although the prediction accuracy of hypoxic events was slightly worse, the general time series characteristics of abrupt DO depletion were captured. Water temperature regularly affects DO concentrations due to its periodic variations. The high correlation and the universal importance of total nitrogen (TN) and total phosphorus (TP) with DO reveals that point source pollution are critical cause of DO depletion in the freshwater lake. The importance of NTU at the Zhong Miao Station indicates the self-purification capacity of the lake is affected by the flow rate changes brought by the tributaries. Calculating linear correlations of variables in conjunction with a permutation variable importance analysis enhanced the interpretability of the proposed model results. This study demonstrates that the AC-BiLSTM model can complete the task of short-term prediction of DO concentration of lakes and reveal its response features of timing and magnitude of abrupt DO depletion., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Impounded lakes are often interconnected in large-scale water diversion projects to form a coordinated system for water allocation and regulation. The alternating runoff and transferred water can significantly impact local ecosystems, which are initially reflected in the sensitive phytoplankton. Nonetheless, limited information is available on the temporal dynamics and assembly patterns of phytoplankton community in impounded lakes responding to continuous and periodic water diversion. Herein, a long-term monitoring from 2013 to 2020 were conducted to systematically investigate the response of phytoplankton community, including its characteristics, stability, and the ecological processes governing community assembly, in representative impounded lakes to the South-to-North Water Diversion Project (SNWDP) in China. In the initial stage of the SNWDP, the phytoplankton diversity indices experienced a decrease during both non-water diversion periods (8.5 %∼21.2 %) and water diversion periods (5.6 %∼12.2 %), implying a disruption in the aquatic ecosystem. But the regular delivery of high-quality water from the Yangtze River gradually increased phytoplankton diversity and mediated ecological assembly processes shifting from stochastic to deterministic. Meanwhile, reduced nutrients restricted the growth of phytoplankton, pushing species to interact more closely to maintain the functionality and stability of the co-occurrence network. The partial least squares path model revealed that ecological process (path coefficient = 0.525, p < 0.01) and interspecies interactions in networks (path coefficient = -0.806, p < 0.01) jointly influenced the keystone and dominant species, ultimately resulting in an improvement in stability (path coefficient = 0.878, p < 0.01). Overall, the phytoplankton communities experienced an evolutionary process from short-term disruption to long-term adaptation, demonstrating resilience and adaptability in response to the challenges posed by the SNWDP. This study revealed the response and adaptation mechanism of phytoplankton communities in impounded lakes to water diversion projects, which is helpful for maintaining the lake ecological health and formulating rational water management strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The continuous increase in sulfate (SO 4 2- budgets in freshwater lakes. Here we conducted a field investigation in the lakes along the highly developed Yangtze River basin, China, additionally, we analyzed long-term data (1950-2020) from Lake Taihu, a typical eutrophic lake worldwide. We observed a gradual increase in SO 4 concentrations up to 100 mg/L, which showed a positive correlation with the trophic state of the lakes. The annual variations indicated that eutrophication intensified the fluctuation of SO 4 2- concentrations up to 100 mg/L, which showed a positive correlation with the trophic state of the lakes. The annual variations indicated that eutrophication intensified the fluctuation of SO 4 2- concentrations. A random forest model was applied to assess the impact of SO 4 2- concentrations on CH 4 emissions, revealing a significant negative effect. Synchronously, a series of microcosms with added SO 4 2- were established to simulate cyanobacteria decomposition processes and explore the coupling mechanism between sulfate reduction and CH 4 production. The results showed a strong negative correlation between CH 4 concentrations in eutrophic lakes when estimating global CH 4 2- levels (R 2 = 0.83), indicating that higher initial SO 4 2- concentrations led to lower final CH 4 concentrations. This was attributed to the competition for cyanobacteria-supplied substrates between sulfate reduction bacteria (SRB) and methane production archaea (MPA). Our study highlights the importance of considering the unexpectedly increasing SO 4 2- concentrations in eutrophic lakes when estimating global CH 4 emission budgets., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Climate change and human activities have crucial effects on the variations in phytoplankton blooms in lakes worldwide. A record-breaking heatwave and drought event was reported in the middle and lower reaches of the Yangtze River during the summer of 2022, but only little is known about how cyanobacterial blooms in lakes respond to such climate extremes. Here, we utilized MODIS images to generate the area, occurrence, and initial blooming date (IBD) of cyanobacterial blooms in Lake Chaohu from 2000 to 2022. We found that the area and occurrence of cyanobacterial blooms were largely reduced. At the same time, the IBD was delayed in 2022 compared with the previous 20 years. The annual occurrence and mean area of cyanobacterial blooms in 2022 were 17 % and 23.1 km 2 , respectively, which were the lowest reported levels since the 21st century. The IBD in 2022 was four months late compared with the IBD in 2020. The high wind speed in spring delayed the spring blooms in 2022. The record-breaking heatwaves and drought from June to August reduced the blooms by influencing the growth of cyanobacteria and reducing the flow of nutrients from the watershed into the lake. This study highlights the compound impact of heatwave and drought climate events on reducing cyanobacterial blooms in a long-term period, enhancing additional understanding of the changes in phytoplankton blooms in lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

During the process of cleaning aquaculture ponds, the drainage contributes significantly to antibiotic pollution in the surrounding water environment. Therefore, we conducted a study on the distribution of 26 antibiotics in 57 ponds within the Taihu Lake basin. The results revealed that the detection frequency of antibiotics ranged from 1.75 % to 80.7 %, with the overall detection concentrations ranging from 3.27 to 708.72 ng/L. Among them, the detection rate of 8 antibiotics exceeded 50 %. Regarding the spatial distribution, the concentration of antibiotics was relatively high in aquaculture ponds located in the Changzhou area, with the highest concentration reaching 708.72 ng/L. This observation is likely due to the large size and intensive breeding practices in Changzhou. Fish ponds exhibited a significantly higher total antibiotic concentration of 3.27 to 445.57 ng/L compared to crab ponds (13.01 to 206.30 ng/L) and shrimp ponds (23.17 to 107.40 ng/L). Quinolones and sulfonamides were the predominant antibiotic classes found in fish ponds, accounting for 51.49 % of the total antibiotic concentration. Notably, sulfamethoxazole (SMX) and enrofloxacin (ENR) exhibited the highest antibiotic concentrations. Risk assessments demonstrated that SMX, ENR, and ofloxacin (OFX) contributed significantly to ecological risks. Furthermore, the study found that the tertiary constructed wetland treatment process achieved a remarkable removal rate of 92.44 % for antibiotics in aquaculture wastewater, while other treatment processes displayed limited effectiveness in removing antibiotics. This study addresses the knowledge gap concerning antibiotic pollution during the cleaning process of aquaculture ponds within the Taihu Lake basin., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Organic phosphorus (Po) mineralization hydrolyzed by alkaline phosphatase (APase) can replenish bioavailable P load in the sediment water ecosystem of lakes. However, the understanding about the interaction between P load and bacteria community encoding APase generation in the sediment are still limited. Different P pools in the sediments from Taihu Lake, China were measured using sequential extraction procedure. The APAase activity (APA) were obtained accompanying with enzymatic dynamical parameters Vmax and Km. The abundances and diversity of gene phoD-harboring bacterial communities were assessed using high throughput sequencing. The analysis results showed the decrease of potentially bioavailable P fractions including MgCl 2 -P and Fe-P along sampling gradient southwards together with active P concentrations in the water. Conversely, increasing APA and absolute abundance of phoD gene were found with the decreasing of P loads southwards. Positive correlation (p < 0.05) between absolute abundance and APA indicated that phoD-encoding bacteria manipulated the APA and Po mineralization. Negative correlation (p < 0.01) suggested that the APA was restrained by high P load and was promoted under low P condition. However, higher Vmax and Km values suggested that high mineralization potential of Po maintained the high concentrations of potentially bioavailable P even the APA was restricted. The abundance increase of predominant genus Cobetia (from 15.51 to 24.34 %) mirrored by the reduced Calothrix abundance (from 24.65 to 1036 %) was speculated to be responsible for the APA promotion under low P condition. Higher diversity indices in the high P scenario suggested that high P load stimulated the ecological diversity of gene phoD-encoding bacteria community. Generally, rare taxa such as Burkholderia having high connected degrees in bacterial communities together with abundant genera synergistically manipulated the phoD gene abundance and APase generation. Interaction between P fractions and bacteria encoding phoD gene determined the eutrophication status in the lacustrine ecosystem., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Lake Erhai is a potentially phosphorus (P)-limited lake and its water quality may have been affected by atmospheric P deposition. However, there have been few studies on atmospheric P deposition in this lake. In this study, we established five wet deposition monitoring sites and two dry deposition monitoring sites around Lake Erhai to quantify the wet and dry deposition of total phosphorus (TP), including dissolved inorganic phosphorus (DIP), dissolved organic phosphorus (DOP) and particulate phosphorus (PP) from July 2022 to June 2023. Wet deposition fluxes of P species were collected by automatic rainfall collection instrument, and dry deposition fluxes were estimated using airborne concentration measurements and inferential models. The results reveal that among the different P components, DOP had the highest contribution (50%) to wet TP deposition (average all sites 12.7 ± 0.7 mg P m 2 /yr), followed by PP (40%) and DIP (10%). Similarly, DOP (51%) was the major contributor to dry TP deposition (average two sites 2.4 ± 0.9 mg P m 2 /yr), followed by DIP (35%) and PP (14%). Wet deposition dominated the annual total TP deposition (wet plus dry), accounting for approximately 83%. The key seasons for dry deposition were spring and autumn, which accounted for 64% of the annual total dry TP deposition. In comparison, wet deposition was significantly higher in the summer, accounting for 73% of the annual total wet TP deposition. The results of the potential source contribution function and concentration-weighted trajectories analysis indicate that local source emission and long-range transport from surrounding cities jointly exerted a substantial influence on aerosol P concentrations, particularly in the eastern and northwestern regions of the lake. These findings provide a comprehensive understanding of the different P components in atmospheric deposition, which is beneficial for developing effective strategies to manage the P cycle in Lake Erhai., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Tungsten (W) can be toxic to aquatic organisms. However, the spatiotemporal characteristics and controlling factors of W mobility during harmful algal blooms (HABs) have rarely been investigated. In this study, simultaneous changes in soluble W, iron (Fe), manganese (Mn), and ultraviolet absorbance (UV 254 ) in the sediment-water interface (SWI) were measured monthly using high-resolution peeper (HR-Peeper) devices. Laboratory experiments were conducted to verify the effects of environmental factors on W release. From May 2021 to October 2021, the concentration and flux of soluble W were higher than in other months. In addition, from May to October, D MAX (the depth at which the maximum concentration occurs on each profile) was 30-50 mm below the SWI, rather than the maximum depth. Principal component analysis (PCA) also divided the year into two periods, designated W-stable (December 2020, January, March, April and November 2021 with low soluble W concentration) and W-active periods (from May 2021 to October 2021 with high soluble W concentration). Laboratory experiments showed that both warming and anoxic conditions caused simultaneous release of soluble W, Fe(II), Mn, and dissolved organic matter (DOM), with strong correlations among soluble W, Fe(II), Mn. Partial least squares path modeling (PLS-PM) and random forest model showed that DOM directly affected W release or indirectly affected W release through promoting ferromanganese (oxyhydr)oxides reduction under warming and anaerobic conditions. The results of the field investigation showed that, in the W-stable period with low T, high DO, and an oxic SWI, the concentrations of soluble W, Fe, Mn, and DOM were low. The redundancy analysis (RDA) showed that these months were mainly affected by water DO. The significant and strong positive correlation among soluble W, Fe and Mn indicated that soluble W was probably scavenged by Fe/Mn (oxyhydr)oxides in the oxic water during the W-stable period. The W-active period corresponded to the cyanobacterial HABs (cyanoHABs) outbreak, with higher T, lower DO, and a more anoxic SWI. During this period, the concentrations of soluble W, Fe, Mn, and DOM were high and their correlations were stronger. RDA showed that these months were mainly affected by T, UV 254 , soluble Fe and Mn. These results indicated that reductive dissolution of Fe/Mn (oxyhydr)oxides driven by DOM generated in W-active period, especially cyanoHAB-derived DOM, mainly caused soluble W release. These results reveal the coupling relationship between cyanoHABs and W release and emphasize the need for prevention and control of heavy metal release in eutrophic lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Exploring the impact factors associated with biodiversity and the relationship between them has always been a concerned issue in recent years. However, the previous research mostly focus on theoretical layer. Accordingly, the relationship between landscape pattern and biodiversity is to be analyzed in this research. The landscape pattern determines the function and ecological process of the landscape, and affects the species flow, information flow and energy flow in the landscape. Land use patterns has inevitably left an impact on the landscape pattern. Landscape pattern determines the function and ecological process of landscape and thus plays a significant role in biodiversity. East Dongting Lake National Nature Reserve is taken as the research object of the paper, and the remote sensing image data of three different time periods are collected, including 2000, 2010 and 2020. With an interpretation of the vegetation landscape pattern changes inside the protected area to collect and analyze the vegetation coverage. By comparing landscape patterns and the dynamic changes of land use in different periods of time, the correlation between landscape pattern characteristics and regional biodiversity is to be analyzed. Research shows: (1) From 2000 to 2020, the vegetation coverage of East Dongting Lake increased, but the landscape shape, scale, diversity and uniformity index decreased to varying degrees. (2) At the class level of landscape type, the relationship between landscape index and biodiversity is different. A complex relationship between farmland landscape and biodiversity. There is a significant positive correlation between the index of grassland landscape type and the index of regional biodiversity. (3) The correlation analysis results at the landscape level show that the landscape characteristic index is positively correlated with the regional biodiversity index. The grassland landscape in the area is the main habitat of biological species. At the same time, as the main grain producing area, the impact of farmland landscape cannot be ignored. This study has certain theoretical guiding significance for the protection and management of biodiversity in the region in terms of maintaining landscape pattern in particular the grassland landscape area and increasing vegetation coverage in the process of land use., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Water diversion can effectively alleviate water resource shortages and improve water environmental conditions, while also causing unknown ecological consequences, in particular, the assembly mechanism of zooplankton communities in the affected areas will become more complex after long-term water transfer. Taking Nansi Lake, the second largest impounded lake along the eastern route of China's South to North Water Diversion Project (SNWDP), as an example, the composition and diversity of zooplankton communities in the lake area and estuaries during the water diversion period (WDP) and non-water diversion period (NWDP) were studied. The potential assembly process of zooplankton communities was further explored, and the stability of communities in different regions during different periods was compared. The related results indicated that the changes in water quality conditions induced by water diversion had a relatively weak impact on the zooplankton communities. In the assembly mechanism of zooplankton communities, stochastic process played a more important role during both WDP or NWDP, and the proportion of deterministic process was relatively higher during NWDP, which may be related to the greater role of total nitrogen (TN) in the assembly of the zooplankton communities. The network analysis and cohesion calculation results showed that the stability of the zooplankton communities in the lake area sites was higher than that in the estuary sites, and the stability during NWDP was higher than that during WDP. In sum, the stability of zooplankton communities displayed a degree of change affected by water diversion activities, but the community assembly was not significantly influenced by the water quality fluctuations after about relatively long-term water diversion. This study provides an in-depth understanding of the ecological effects of water diversion on the biological communities in the affected lake, which is beneficial to the management and regulation of long-term water diversion projects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The study of the fractions and distribution characteristics of organic phosphorus in the sediment of the water level fluctuating zone of Nansi Lake is conducive to revealing the transformation of phosphorus in the lake, and has important scientific significance for controlling the eutrophication of Nansi Lake. Based on the sediment of the water level fluctuation zone of Nansi Lake. The improved Hedley continuous grading extraction, ultraviolet-visible spectroscopy and three-dimensional fluorescence spectroscope were used to characterize the structural characteristics and stability of organic molecules in the sediment, and to reflect the differences in the structure and stability of organophosphate in the water level fluctuating zone. Principal component analysis (PCA), Redundancy analysis (RDA) and correlation heat map analysis were used to analyze the correlation between phosphorus and physicochemical index. The results showed that the alternation between wet-dry conditions was more favorable for the release of phosphorus from sediment, compared to continuous inundation conditions. Moreover, the higher the frequency of wet-dry alternations, the greater the release of phosphorus in different forms from the sediment. Wet-dry alternation resulted in a reduction of substituent on the aromatic rings of sediment DOM (dissolved organic matter), and the continuous drying would increase the molecular weight and humidification degree of DOM in the sediment. Correlation analysis showed that NaOH-P o content in sediment was significantly negatively correlated with TP, IP, OP and various organophosphorus forms, indicating a close transformation relationship between phosphorus forms in sediment. The results can provide a scientific basis for controlling the release of endogenous phosphorus and the risk of eutrophication in Nansi Lake., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Nutrient loads in lakes are spatially heterogeneous, but current spatial analysis method are mainly zonal, making them subjective and uncertain. This study proposes a high-resolution model for assessing spatial differences in nutrient loads based on the lattice Boltzmann method. The model was applied to Dongping Lake in China. Firstly, the contribution rates of four influencing factors, including water transfer, inflow, wind, and internal load, were calculated at different locations in the lake. Then, their proportionate contributions during different intervals to the whole lake area were calculated. Finally, the cumulative load could be calculated for any location within the lake. The validation showed that the model simulated hydrodynamics and water quality well, with relative errors between the simulated and measured water quality data smaller than 0.45. Wind increased the nutrient loads in most parts of the lake. The loads tended to accumulate in the east central area where high-frequency circulation patterns were present. Overall, the proposed water quality model based on the lattice Boltzmann method was able to simulate seven indexes. Therefore, this model represents a useful tool for thoroughly assessing nutrient load distributions in large shallow lakes and could help refine lake restoration management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Situated in the north of the Qinghai-Tibet Plateau, the Qaidam Basin experiences limited precipitation and significant evaporation. Despite these conditions, it stands out as one of the most densely distributed lakes in China. The formation of these lakes is controversial: whether the lake water primarily originates from local precipitation or external water sources. To address this issue, this paper explores the recharge sources of lakes in the Qaidam Basin and the circulation patterns of groundwater from a remote sensing perspective. Based on deep learning networks, we optimized the soft object regions of the Object-Contextual Representations Network (OCRNet) and proposed the Remote·Sensing Adaptive-Improved OCRNet (RSA-IOCRNet). Compared with seven other networks, RSA-IOCRNet obtained better experimental results and was used to construct an area sequence of 16 major lakes in the Qaidam Basin. Combined with multi-source data, the comprehensive analysis indicates no significant correlation between climatic factors and lake changes, while an obvious correlation between lakes and groundwater changes in the eastern Qaidam, consisting with the results of the field survey. Deep-circulating groundwater recharges numerous Qaidam lakes through upwelling from fault zones, such as Gasikule Lake and Xiaochaidan Lake. Groundwater in the Qaidam Basin is more depleted in hydrogen-oxygen isotope characteristics than surface water in the basin, but similar to some river water in the endorheic Tibetan Plateau. This indicates that Tibetan seepage water, estimated at approximately 540 billion m 3 /a, is transported through the Qaidam Basin via deep circulation. Moreover, it rises to recharge the groundwater and lakes within this basin through fracture zones, extending to various arid and semi-arid regions such as Taitema Lake. This work provides a new perspective on the impact of deep groundwater on lakes and water circulation in these areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Water replenishment is an important measure for maintaining and improving the aquatic environmental quality of lakes. The problems of water quality deterioration and water shortage can be alleviated by introducing water of higher quality. However, the mechanism of water replenishment in the improvement of the water quality and trophic status of lakes remains unclear. This study investigated water replenishment in Wuliangsuhai Lake (WLSHL) from 2011 to 2021 by collecting seasonal water samples and conducting laboratory analyses. Water replenishment was found to be capable of significantly improving lake water quality and alleviating eutrophication. It is worth noting that single long-term water replenishment measures have limitations in improving the water quality and trophic status. The whole process was divided into three stages according to the water quality and trophic status, namely the buffer period, decline period, and stable period. During the buffer period, the water quality and trophic status showed only slight improvement because of the small amount of water replenishment and the low proportion of higher-quality water from the Yellow River. In the decline period, with increasing water replenishment, the proportion of higher-quality water from the Yellow River gradually increased, leading to the most significant and stable degree of improvement. In the stable period, increases in the amount of water replenishment had little effect on improving the water quality and trophic status, which is attributable to the balance between internal pollutants (lake water-sediment), and the balance between internal-external pollutants (lake water-irrigation return flow + Yellow River water). On the premise of stable water quality, with eutrophication control as the management goal, the optimal water replenishment would be approximately 10.58 ×10 8 m 3 . Further necessary measures for solving aquatic environmental problems include the combination of sediment dredging, optimization of the water replenishment route, and implementation of quality management in water replenishment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Transboundary lakes are shared by multiple administrative regions. The key to balance the development and protection of transboundary lakes is to properly measure the value of water resources. Most of previous studies on the measurement of lake water resources value have not fully considered the ecosystem service function. This paper proposes a new concept "composite water value" to measure the value of transboundary lakes by integrating the external runoff value and the internal runoff value of water resources. The study constructs a composite water value measurement system for transboundary lakes, further analyzes its influencing factors,and applies the system to the case of Nansi Lake, a representative transboundary lake in eastern China. The results show that: (1) The composite water value of lakes is influenced by various factors, including industrial structure, water withdrawal, and water use methods, which impact the external runoff water value; meanwhile, the composite water quality and fluctuations in lake level are closely associated with the internal runoff water value. From 2008 to 2021, the average annual composite water value of Nansi Lake was 39.628 billion yuan, exhibiting a "rising-falling-fluctuating rising" trend due to pollution control policies, reduced precipitation, and enhanced water-saving technologies successively. (2) From a long-term perspective, it is necessary to focus on the internal runoff water use value of lakes. The internal runoff water value of Nansi Lake has been over 75% of the composite water value, and flood storage and water conservation are important manifestations of its ecosystem service value. (3) The external runoff water value of lake is closely related to the internal runoff water value, and relevant departments need to consider the balance between the water withdrawal of multiple cities along the lake and the retained water volume of the lake to achieve the maximum benefit of composite water value., Competing Interests: Declaration of competing interest All authors have no conflicts of interest. On behalf of all authors, the corresponding author declares that there is no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The continuous excessive application of phosphorus (P) fertilizers in intensive agricultural production leads to a large accumulation of P in surface soils, increasing the risk of soil P loss by runoff and leaching. However, there are few studies on the accumulation and loss of P from surface soil to deep soil profiles driven by shallow groundwater table (SGT) fluctuations. This study used the intensive cropland around 7 plateau lakes in Yunnan Province as an example and conducted in situ monitoring of P storage in the soil profile and SGT during the rainy season (RS) and dry season (DS) as well as simulation experiments on soil P loss. The aim was to study the spatiotemporal variation in P accumulation in the soil profile of cropland driven by SGT fluctuations in the RS and DS and estimate the P loss in the soil profile driven by SGT fluctuations. The results showed that fluctuations in the SGT promoted P accumulation from the surface soil to deeper soil. The proportions of P stored in various forms in the 30-60 cm and 60-100 cm soil layers in the RS were greater than those in the DS, while the average proportion in the 0-30 cm soil layer in the DS was as high as 48%. Compared with those in the DS, the maximum decreases in the proportion of P stored as TP and Olsen-P in the 0-100 cm soil layer in the RS were 16% and 58%, respectively, due to the rise in the SGT (SGT <30 cm), while the soil TP storage decreased by only 1% when the SGT was maintained at 60-100 cm. The critical thresholds for soil Olsen-P and TP gradually decreased with increasing soil depth, and the risk of P loss in deeper soil increased. The loss of soil P was increased by fluctuations in the SGT. Based on the cropland area around the 7 plateau lakes, P storage, and SGT fluctuations, the average loss intensity and loss amount of TP in the 0-100 cm soil layer around the 7 plateau lakes were estimated to be 25 kg/ha and 56 t, respectively. Therefore, reducing exogenous P inputs, improving soil endogenous P utilization efficiency and maintaining deep soil P retention are the basic strategies for preventing and controlling P accumulation and loss in deep soil caused by SGT fluctuations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Dissolved organic carbon (DOC) components can be highly variable in aquatic ecosystems, and play a pivotal role in the global carbon cycles. To comprehend potential effects of nutrient enrichment on portion of DOC biodegradability (%BDOC), we conducted an extensive investigation on 26 urban lakes in a major metropolitan area in subtropical China in a small gradient of trophic levels from mesotrophic to light and middle eutrophic. In addition to field measurements on lake ambient conditions and laboratory analysis of DOC characteristics, we conducted a 28-day temperature-controlled incubation experiment, in which %BDOC of lake waters was determined. In the mesotrophic waters, %BDOC ranged from 0.6 to 41.4 % (11.2 ± 8.9 %). The %BDOC levels spanned from 5.2 to 20.2 % (10.7 ± 4.0 %) in the light eutrophic waters, and the %BDOC ranged from 2.7 to 35.0 % (13.7 ± 8.4 %) in the middle eutrophic waters. We found a significant change in DOC chemical composition across the study lakes characterized by shifting of trophic levels. Although the experiment found significant changes in the factors that can influence %BDOC, a significant difference was not observed in %BDOC among the three trophic levels. The %BDOC was primarily influenced by the inherent DOC concentration and aromaticity, with eutrophication leading to the varied driving factors of %BDOC in lake systems. We show that most of the lake water DOC was stable. The findings indicate the intricate interplay between biological metabolism and nutrient availability governing %BDOC dynamics in urban lake ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The dramatical increase of sulfur concentration in eutrophic lakes, especially sulfate (SO 4 2- ), has brought attention to the impact on the lake ecosystem; however, the mechanisms driving the intensification of eutrophication and the role of SO₄ 2- dynamics in lakes, this study monitored SO 4 concentrations in water and sediments across seven lakes with varying trophic statuses on a spatial scale, and in the eutrophic Lake Taihu over one year on a temporal scale, as well as a series of microcosms with different initial SO 2- dynamics in lakes, this study monitored SO 4 concentrations in lakes, the highest SO 2- concentrations in water and sediments across seven lakes with varying trophic statuses on a spatial scale, and in the eutrophic Lake Taihu over one year on a temporal scale, as well as a series of microcosms with different initial SO 4 2- concentrations. Exogenous sulfur input is the primary driver of increased SO 4 2- concentrations in lakes, the highest SO 4 2- concentration in overlying water was 100 mg/L, as well as which reached 310.9 mg/L in sediment. The concurrent input of nutrients such as nitrogen and phosphorus exacerbated eutrophication, resulting in the destabilization of the sulfur cycle. Eutrophication promoted the SO 4 2- concentration on the spatio-temporal scale, especially in sediment, and trophic lake index (TLI) showed a positive correlation with the SO 4 concentrations in lakes.2- in sediments (R 2  = 0.99; 0.88). The SO 4 2- concentration in water and TLI showed a nonlinear correlation on the temporal scale (R 2  = 0.44), and showed a positive correlation on the spatial scale (R 2  = 0.49). Microscopic experiments demonstrate that the anaerobic environment created by cyanobacteria decomposition induced sulfate reduction and significantly reduces SO 4 2- concentrations. Concurrently, the anaerobic environment facilitates the coupling of iron reduction with sulfate reduction, leading to a substantial increase in Acid Volatile Sulfides (AVS) in the sediment. These findings reveal that eutrophication has a dual effect on the dynamic change of SO 4 2- concentrations in overlying water, which is helpful to accurately evaluate and predict the change of SO 4 2- concentrations in lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

China has made enormous strides to achieve high-quality development and biodiversity conservation, and the establishment of nature-protected areas is one of the essential initiatives. Caizi Lake involves a natural reserve and two national wetland parks, accommodating winter migratory waterfowl over the middle and lower Yangtze River basin in China. However, the water transfer from the Yangtze River to the Huai River (YR-HR water transfer) has modified the winter hydrological conditions of Caizi Lake, negatively affecting wintertime waterfowl habitats. Hence, conserving wintertime waterfowl habitats necessitates knowledge of the dynamical mechanisms behind the impacts of YR-HR water transfer on wintertime waterfowl habitats and adaptive measures. Here we developed a machine learning model, the normalized difference vegetation index, and on-spot observatory datasets such as the spatial distribution of waterfowl species and underwater topography of Caizi Lake. We found that the rising winter water level of Caizi Lake encroaches on winter waterfowl habitat with extremely high suitability. Meanwhile, rising water levels reduced waterfowl food sources. Thus, rising water levels due to YR-HR water transfer deteriorated waterfowl living conditions over Caizi Lake. Therefore, we proposed adaptive measures to alleviate these negative effects, such as water level regulation, artificial feeding of waterfowls, restoration and reconstruction of contiguous mudflats, grass flats. This study highlights human interferences with waterfowl habitats, necessitating biodiversity conservation at regional scales., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)