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The generation of acid mine drainage (AMD) characterized by high acidity and elevated levels of toxic metals primarily results from the oxidation and dissolution of sulfide minerals facilitated by microbial catalysis. Although there has been significant research on microbial diversity and community composition in AMD, as well as the relationship between microbes and heavy metals, there remains a gap in understanding the microbial community structure in uranium-enriched AMD sites. In this paper, water samples with varying levels of uranium pollution were collected from an abandoned stone coal mine in Jiangxi Province, China during summer and winter, respectively. Geochemical and high-throughput sequencing analyses were conducted to characterize spatiotemporal variations in bacterial diversity and community composition along pollution groups. The results indicated that uranium was predominantly concentrated in the AMD of new pits with strong acid production capacity, reaching a peak concentration of 9,370 µg/L. This was accompanied by elevated acidity and concentrations of iron and total phosphorus, which were identified as significant drivers shaping the composition of bacterial communities, rather than fluctuations in seasonal conditions. In an extremely polluted environment (pH < 3), bacterial diversity was lowest, with a predominant presence of acidophilic iron-oxidizing bacteria (such as Ferrovum), and a portion of acidophilic heterotrophic bacteria synergistically coexisting. As pollution levels decreased, the microbial community gradually evolved to cohabitation of various pH-neutral heterotrophic species, ultimately reverting back to background level. The pH was the dominant factor determining biogeochemical release of uranium in AMD. Acidophilic and uranium-tolerant bacteria, including Ferrovum, Leptospirillum, Acidiphilium, and Metallibacterium, were identified as playing key roles in this process through mechanisms such as enhancing acid production rate and facilitating organic matter biodegradation. [ABSTRACT FROM AUTHOR]

Marine bacterioplankton play a crucial role in the cycling of carbon, nitrogen, and phosphorus in coastal waters. And the impact of environmental factors on bacterial community structure and ecological functions is a dynamic ongoing process. To systematically assess the relationship between environmental changes and bacterioplankton communities, this study delved into the spatiotemporal distribution and predicted metabolic characteristics of bacterioplankton communities at two estuarine beaches in Northern China. Coastal water samples were collected regularly in spring, summer, and autumn, and were analyzed in combination with environmental parameters and bacterioplankton community. Results indicated significant seasonal variations in bacterioplankton communities as Bacteroidetes and Actinobacteria were enriched in spring, Cyanobacteria proliferated in summer. While Pseudomonadota and microorganisms associated with organic matter decomposition prevailed in autumn, closely linked to seasonal variation of temperature, light and nutrients such as nitrogen and phosphorus. Particularly in summer, increased tourism activities and riverine inputs significantly raised nutrient levels, promoting the proliferation of specific photosynthetic microorganisms, potentially linked to the occurrence of phytoplankton blooms. Spearman correlation analysis further revealed significant correlations between bacterioplankton communities and environmental factors such as salinity, chlorophyll a, and total dissolved phosphorus (TDP). Additionally, the metabolic features of the spring bacterioplankton community were primarily characterized by enhanced activities in the prokaryotic carbon fixation pathways, reflecting rapid adaptation to increased light and temperature, as well as significant contributions to primary productivity. In summer, the bacterial communities were involved in enhanced glycolysis and biosynthetic pathways, reflecting high energy metabolism and responses to increased light and biomass. In autumn, microorganisms adapted to the accelerated decomposition of organic matter and the seasonal changes in environmental conditions through enhanced amino acid metabolism and material cycling pathways. These findings demonstrate that seasonal changes and human activities significantly influence the structure and function of bacterioplankton communities by altering nutrient dynamics and physical environmental conditions. This study provides important scientific insights into the marine biological responses under global change. [ABSTRACT FROM AUTHOR]

Monopterus albus is one of China's renowned and superior aquaculture species, with its seedlings mainly sourced from wild capture. One of the bottlenecks in M. albus aquaculture is the high mortality rate and low feeding initiation rate from stocking wild fry to the initiation of feeding. In production, trash fish is commonly used to wean M. albus juveniles onto feeding. In this study, we introduced three other natural feeds, earthworms (EW), yellow mealworms (YMW), and fly maggots (FM), with frozen trash fish (TF) serving as the control group, to evaluate the effects of these four natural feeds on the survival rate, feeding initiation, antioxidant enzymes activity, and body composition of M. albus juveniles under recirculating water aquaculture conditions. The experiment comprised four treatments, each with three replicates. Each replicate consisted of stocking 150 M. albus juveniles weighing 10.02 ± 0.89 g in size, raised for 5 weeks. The survival rate of the YMW group was 73.33%-85.33%, which was significantly higher than that of the other three bait groups (p < 0.05). The four bait groups showed no significant differences in final body weight and specific growth rate (SGR) (p > 0.05). The EW group showed the highest final body weight, with an average SGR of 2.73, whereas the YMW group had an average SGR of 1.87. The average daily feeding amount was significantly higher in EW and YMW groups than in the other two groups (p < 0.05). The percentage of feeding amount to fish weight in the EW group reached 7.3% in the fifth week. After 5 weeks of cultivation, NO2--N content was significantly higher in the waters of the TF and EW groups than in the waters of the FM and YMW groups (p < 0.05), there was no significant difference in TAN content among the treatment groups (p > 0.05). Liver malondialdehyde content was significantly higher in the TF group than in the other bait groups (p < 0.05). GSH-Px activity was significantly higher in the EW group than in the FM group and YMW group. No significant differences in SOD and CAT activity and T-AOC were observed among the bait groups (p > 0.05). The increase in crude protein content was significantly higher in the TF group than in the FM group, but the increase in crude ash content was significantly lower in the TFgroup. In conclusion, Tenebrio molitor could potentially serve as one of the alternative feeds during the initial stages of M. albus juveniles stocking. [ABSTRACT FROM AUTHOR]

Beibu Gulf is an important semi-enclosed bay located in the northwestern South China Sea, and is famous for its high bio-productivity and rich bio-diversity. The fast development along the Beibu Gulf Economical Rim has brought pressure to the environment, and algal blooms occurred frequently in the gulf. In this study, surface water samples and micro-plankton samples (20-200 µm) were collected in the northern Beibu Gulf coast. Diversity and distribution of eukaryotic planktonic microalgae were analyzed by both metabarcoding and microscopic analyses. Metabarcoding revealed much higher diversity and species richness of microalgae than morphological observation, especially for dinoflagellates. Metabarcoding detected 144 microalgal genera in 8 phyla, while microscopy only detected 40 genera in 2 phyla. The two methods revealed different microalgal community structures. Dinoflagellates dominated in microalgal community based on metabarcoding due to their high copies of 18 s rRNA gene, and diatoms dominated under microscopy. Altogether 48 algal bloom and/or toxic species were detected in this study, 34 species by metabarcoding and 19 species by microscopy. Our result suggested a high potential risk of HABs in the Beibu Gulf. Microalgal community in the surface water samples demonstrated significantly higher OTU/species richness, alpha diversity, and abundance than those in the micro-plankton samples, although more HAB taxa were detected by microscopic observations in the micro-plankton samples. Furthermore, nano-sized taxa, such as those in chlorophytes, haptophytes, and chrysophyceans, occurred more abundantly in the surface water samples. This study provided a comprehensive morphological and molecular description of microalgal community in the northern Beibu Gulf. [ABSTRACT FROM AUTHOR]

Estuarine wetlands are characterized by high biodiversity and active fluctuations in redox-sensitive metals (RSMs). In this study, sediment samples were collected from two sites, one with and one without vegetation, in the Yellow River Estuary Wetland (YREW). Active forms of Fe, Mn, and U were extracted using Tessier's sequential extraction method, the bacterial community was analyzed through high-throughput sequencing, and the impact of the community on the RSMs was evaluated. The results indicated that the high nutrient content generated by vegetation withering had a positive effect on bacterial biodiversity, which led to high biomass and a wide variety of species in the sediments. Redox conditions and nutrient levels were the main factors influencing bacterial community structure. Under reducing conditions, genera such as Desulfococcus and Desulfosarcina were the main bacteria mediating the reduction of active Fe and Mn. Bacteria in genera such as Desulfatiglans and Desulfotomaculum were the main bacteria mediating the reduction of active U. These bacteria may result in obvious changes in the release of Fe, Mn, and U from salt marshes to nearshore regions. Our results can help to elucidate the interactions of bacteria and RSMs. [ABSTRACT FROM AUTHOR]

Cylindrospermopsis raciborskii- dominated harmful algae blooms have been reported globally in recent years. However, our understanding of the ecology of C. raciborskii in natural conditions is still poor. In this study, we collected the water samples from a C. raciborskii -blooming lake, Yilong Lake, in Yunnan province, China, and used both culture-dependent and culture-independent approaches to investigate their microbial communities and the interactions between C. raciborskii and the other bacteria. The composition and diversity of microbial communities were revealed with 16S rRNA gene high-throughput sequencing data analysis. Microbial co-occurrences analysis suggests C. raciborskii may have complex associations with other bacteria. Based on co-inoculation tests, we obtained 14 strains of bacterial strains from the water samples that exhibited either algicidal or promoting effects on a strain of C. raciborskii. Two bacterial isolates exhibited a consistent performance between co-occurrence analysis and experimental results. Effects of these bacteria-algae interspecies interactions on the bloom event are discussed. All these results may provide new insights into the C. raciborskii -dominated blooms and how its interspecies relationships with other bacteria may influence the bloom events in eutrophic waters throughout the world. [ABSTRACT FROM AUTHOR]

Dimethyl sulfides are ubiquitous odorous substances in eutrophic freshwater bodies. In this study, a simple headspace solid-phase microextraction-gas chromatography-flame photometric detection method was developed to detect three representative algal-derived dimethyl sulfides in freshwater lake water samples: dimethyl monosulfide (DMS), dimethyl disulfide (DMDS), and dimethyl trisulfide (DMTS). The effects of extraction fiber, temperature, pH, ionic strength, and sample volume were investigated orthogonally, and the optimized method was applied to analyze surface water samples from Lake Ulansuhai in Inner Mongolia, China. Optimal extraction was obtained with a 50/30 µm DVB/CAR/PDMS extraction fiber, 20% ion concentration, 87 min extraction time, and 50 °C extraction temperature. The correlation coefficients of the standardized working curves for DMS, DMDS, and DMTS were 0.9967, 0.9907, and 0.9994, respectively, indicating good linear relationships. Limits of detection were in the nanogram range, and the recoveries of the spiked standards for DMS, DMDS, and DMTS were 97.22~99.07%, 93.39~99.34%, and 91.17~99.25%, with relative standard deviations of 5.18~5.94%, 3.08~6.25%, and 2.56~5.47%, respectively. This method is stable and reliable, and can be used for the determination of volatile sulfides in freshwater lake water. [ABSTRACT FROM AUTHOR]

As an emerging contaminant, microplastics (MPs) have caused global environmental pollution and become the focus of current research. This research presents a comprehensive literature review on the occurrence and distribution characteristics of MPs in surface water within China. The findings demonstrate that stainless steel barrels currently serve as the predominant tool for water sampling, whereas Fourier Transform Infrared spectrometer and Raman spectrometer are extensively employed for the detection of MPs. The mean abundance of MPs in rivers ranges from 0.57 to 930.00 n/L, while in lakes and reservoirs, it varies between 1.30 and 27.50 n/L. The size of MPs in surface waters is mainly less than 1 mm, with the transparent or white fibrous forms being the most frequently observed morphology, and polypropylene and polyethylene emerge as the primary polymer types. Additionally, the investigation of MPs in lakes and reservoirs in Northeast China and South China remains unexplored. Currently, an increasing number of Chinese cities are opting for surface water as their water source, so more studies should focus on enhancing the accumulation of research data on MPs in surface water to provide substantial support for the development of pollution control measures in the future. [ABSTRACT FROM AUTHOR]

The Diannong River, a valuable river and lake resource of the northern Ningxia Yellow River Irrigation Area, plays an instrumental role in regional flood control, drought resistance, climate regulation, and biodiversity conservation. Phytoplankton and zooplankton, as crucial elements of the aquatic ecosystem, have their distribution patterns evaluated and potential influencing factors identified, thereby enhancing the understanding of community distribution patterns. Nested structures and interspecies interaction relationships bear significant implications for community distribution patterns, functions, and stability. The upstream section of the Diannong River in Yinchuan City was chosen as the study object. Water samples were collected in January, April, July, and October 2021, and the community composition of phytoplankton and zooplankton was analyzed using relative abundance, density, and biomass. The distribution matrix temperature and bipartite network methodologies were deployed to investigate their nested pattern and interaction network seasonal characteristics. The findings indicate that the water environment of the Diannong River's upstream section displays pronounced spatiotemporal heterogeneity, characterized by weak alkalinity and high fluoride content. The plankton community composition and relative abundance showed marked differences among the distinct sampling periods. The temperature of the random distribution matrix shows a significant difference compared to the zero-sum model, revealing a notable nested pattern in plankton in the Diannong River's upstream section. The bipartite network suggests that the plankton composition was the simplest in January and the most complex in July, with the fiercest species competition observed in January and the lowest levels of species specificity, vulnerability, and generality. Water temperature (WT), dissolved oxygen (DO), total phosphorus (TP), available phosphorus (AP), CODCr, F−, and Cl− constitute the environmental parameters influencing the overall structure of the phytoplankton community in the Diannong River's upstream section, whereas zooplankton did not present a significant correlation with water environmental factors. [ABSTRACT FROM AUTHOR]

South China Mountain Region has a well-developed water system with the most abundant water in China. Untreated natural water is the main source of drinking water for the local people. This study aimed to investigate the hydrochemical characteristics and trace element concentrations of natural water in the mountainous regions of South China. In this study, 116 water samples were collected. Traditional hydrochemical methods, water quality index (WQI), hazard index (HI), and nutrient speciation of trace elements (NSTE) were used for analysis. In general, the hydrochemical type was mainly Ca-HCO3− type. The hydrochemical characteristics were mainly influenced by the weathering of calcite and silicate rocks. Overall total dissolved solids (TDS) were low, indicating mainly soft and very soft water. The water that met the standards for mineral water had an average concentration of 59.69 mg/L for Sr (strontium) and an average concentration of 0.46 mg/L for H2SiO3 (silicic acid). Although the water quality index (WQI) indicated that 91.3% of the water samples in the study area were of good quality (WQI < 25), 2.58% of the water samples had significant non-carcinogenic risk (HI > 1) due to the high As and Pb concentrations. The water in the study area contributed significantly to human intake of Sr, Cr, and V, accounting for 8.4, 8.3, and 7.7% of the required daily intake for adults, respectively. It is recommended that a comprehensive water quality evaluation system be constructed to ensure that mountain water is managed for development and safe to drink. [ABSTRACT FROM AUTHOR]

The compression release of pore water in clayey aquitards has a significant impact on groundwater quality. Iron is an active variable element that mediates biochemical reactions in groundwater systems, but its transformation mechanisms in clayey aquitards remain unclear. The sediment and pore water samples from the shallow clayey aquitard (thickness = ~20 m) in the Chen Lake area of China were collected in three boreholes. The spatial distribution and influencing factors of Fe occurrence in the aquitard were revealed using hierarchical extraction, statistical analysis, and simulation calculations. The results indicate that the background value of alluvial–lacustrine sediments primarily affects the Fe concentration of clayey sediments. The dissimilatory reduction in free Fe oxide was the main source of Fe ions in pore water, resulting in a major percentage of Fe2+ in the total Fe concentration (0.07−5.91 mg/L). The abundant organic matter in organic-rich clay promoted a dissimilatory reduction in Fe (III) oxides, while the Fe concentrations of sediment and pore water were lower in the sand-rich stratum because of its weak adsorption capacity. The impact of human reclamation activities on the aquitard was mainly concentrated in the shallow layer ( > − 3   m ), resulting in water drainage and O2 and CO2 input, which induced the crystallization of poorly crystalline Fe oxides. The input of reactive organic matter from reclaimed crops promoted the dissimilatory reduction in Fe oxides and the enrichment of Fe in deep pore water. The copious Fe2+ in deep stratum pore water tended to interact with CO32− and S2− to form coprecipitation with Fe (II). The concentrations of As, Cr, Sr, Zn, and Mn in pore water followed a similar variation trend to the Fe ion concentration, and their release could be attributed to the reduction dissolution of sediment Fe (III) oxides. [ABSTRACT FROM AUTHOR]

A combined temporal and spatial research approach helps us to evaluate the ecological status of a river scientifically and comprehensively. To understand the response mechanisms of bacteria in the Li River to different environments, we conducted a 1-year study (2020–2021) and collected water samples from 18 sections of the river in October, January, April, and August. 16S sequencing was used to study the composition and structure of bacterial communities in Li River at different temporal and spatial scales. The results showed that NO3−-N, TP, T, pH, and DO were significantly different on spatial and temporal scales. Alpha diversity of planktonic bacteria in Li River fluctuated significantly with the season, reaching its highest in summer. Proteobacteria remained the most dominant phylum in all seasons, but the differential microorganisms varied between seasons. Although the abundance of metabolic functions of planktonic bacteria did not show significant differences between seasons, we found that DO, TP, T, and COD were the key environmental factors affecting bacterial metabolism. In addition, the co-occurrence network analysis showed that the autumn network had a higher number of nodes and edges and exhibited a high degree of complexity, while the summer network had the highest degree of modularity and exhibited greater stability. These results deepen our knowledge of the response mechanisms of river microorganisms to temporal and spatial changes and provide a scientific reference for the study of river ecosystems. [ABSTRACT FROM AUTHOR]

Context. The environmental occurrence of metformin has been frequently world-widely reported. Despite the diabetes susceptibility in the Chinese population, the studies on occurrence of metformin as environment disruptor in China are insufficient. Objective. To determine the occurrence trends and possible environmental pollution sources of metformin as an emerging micropollutant. Methods. High-performance liquid chromatographyelectrospray ionization-tandem mass spectrometry system was used to detect the metformin levels in water samples collected from the Xi'an city Moat, China once a year from 2017 to 2021. Correlations among the metformin levels in moat water, in surrounding hospital wastewater, and hospital metformin consumption data were assessed using Pearson, Spearman and Kendall's tau-b correlation coefficients. Results. Occurrence of metformin was found in Xi'an city Moat water with levels in the range of 304-793 ng/L. Significant correlations were found between the metformin levels in city moat water and the total (or outpatient) metformin utilization data of the hospital. Conclusion. Data suggested the potential environmental issues posed by metformin in Xi'an city in China. The metformin consumption volume in the surrounding hospitals, especially at the outpatient services, could be used to predict the metformin concentrations in the moat water. [ABSTRACT FROM AUTHOR]

The lithium concentrations in the geothermal waters of the Wumishan Formation carbonate reservoir in China Xiong'an New Area are over 1 mg/L and are even higher than those in the geothermal waters of granite reservoirs in some areas of China. It is still unknown which are the most important factors controlling the lithium concentrations in the geothermal waters in the study area. This article selected the analysis and test data of 32 geothermal water samples obtained in recent years from the study area and combined them with hydrochemical analysis and test data from granite reservoirs in other regions of China to study the enrichment mechanism of lithium in the geothermal waters in the study area. The results of the hydrochemical data analysis indicate that the lithology, pH, and water–rock interaction between geothermal water and carbonate rocks are not the main factors affecting the lithium concentrations in the study area. The mixing of paleo-seawater and the leaching of the evaporated rocks formed by it are the most important factors controlling the lithium concentrations in the study area, and temperature is also an important factor affecting the lithium concentrations. The research results are of great significance to the study of the enrichment mechanism of lithium in geothermal waters and the formation mechanism of geothermal waters in similar areas around the world. [ABSTRACT FROM AUTHOR]

Viruses existed in wastewaters might pose a biosecurity risk to human and animal health. However, it is generally difficult to detect viruses in wastewater directly as they usually occur in low numbers in water. Therefore, processing large volumes of water to concentrate viruses in a much smaller final volume for detection is necessary. Glass wool has been recognized as an effective material to concentrate multiple in water, and in this study, we assessed the use of glass wools on concentrating pseudorabies virus (PRV), African swine fever virus (ASFV), and porcine epidemic diarrhea virus (PEDV) in water samples. The influence of pH values, water matrix, water volume, filtration rate, temperature on the effect of the method concentrating these viruses for detection was evaluated in laboratory. Our results revealed that glass wool was suitable for the concentration of above-mentioned viruses from different water samples, and demonstrated a good application effect for water with pH between 6.0-9.0. Furthermore, glass wool also showed a good recovery effect on concentrating viral nucleic acids and viral particles, as well as living viruses. In addition, combining use of glass wool with skim milk, polyethylene glycol (PEG)-NaCl, or ultracentrifuge had good effects on concentrating ASFV, PRV, and PEDV. Detection of wastewater samples (n = 70) collected from 70 pig farms in 13 regions across Hubei Province in Central China after glass-wool-concentration determined one sample positive for ASFV, eighteen samples positive for PRV, but no sample positive for PEDV. However, these positive samples were detected to be negative before glass wool enrichment was implemented. Our results suggest that glass wool-based water concentration method developed in this study represents an effective tool for detecting viruses in wastewater. [ABSTRACT FROM AUTHOR]

A protocol of distributed sampling on water and sediment of two rivers of Chaohu Basin was carried out in different seasons and under different hydrological conditions. Water samples were analyzed for total phosphorus (TP) and dissolved phosphorus (DP), and sediments for TP, organic phosphorus (OP), inorganic phosphorus (IP), NaOH extracting phosphorus (NaOH-P), and HCL extracting phosphorus (HCL-P). The results showed that median concentrations of TP and DP in water were 0.09 and 0.05 mg/L, and 0.11 and 0.05 mg/L, and those of TP in sediment were 458.4 and 989.6 mg/kg, respectively, for Fengle and Zhegao during the non-flood period. IP concentrations in sediment were significantly higher than that of OP. The average percentages of OP, NaOH-P, and HCL-P were 35%, 29%, and 36% and 24%, 35%, and 41%, respectively, for Fengle River and Zhegao during the non-flood period. A high spatial difference was observed for most phosphorus fractions of water and sediment of both rivers due to the local influence. Average levels of all forms of phosphorus in the water and sediment were higher in the spring than in other seasons for both rivers, except for OP in the sediment of Zhegao River, probably indicating the influence of fertilization on phosphorus export. TP and DP in water were much higher in the rising stage of the flood than that during non-flood, while it was not the case in the recession stage, demonstrating the flushing effect during the rising stage of the flood. No significant difference was found in the levels of phosphorus fractions in sediment between flood and non-flood, nor between rising and recessing stages. The sources of phosphorus were mixed and both natural and anthropogenic sources contributed to phosphorus in the water and the sediments of both rivers. With higher levels of phosphorus fractions in water and sediment, Zhegao imposed a greater phosphorus exportation risk to Chaohu Lake than Fengle. [ABSTRACT FROM AUTHOR]

Low- and medium-resolution satellites have been a relatively mature platform for inland eutrophic water classification and chlorophyll a concentration (Chl-a) retrieval algorithms. However, for oligotrophic and mesotrophic waters in small- and medium-sized reservoirs, problems of low satellite resolution, insufficient water sampling, and higher uncertainty in retrieval accuracy exist. In this paper, a hybrid Chl-a estimation method based on spectral characteristics (i.e., remote sensing reflectance (Rrs)) classification was developed for oligotrophic and mesotrophic waters using high-resolution satellite Sentinel-2 (A and B) data. First, 99 samples and quasi-synchronous Sentinel-2 satellite data were collected from four small- and medium-sized reservoirs in central China, and the usability of the Sentinel-2 Rrs data in inland oligotrophic and mesotrophic waters was verified by accurate atmospheric correction. Second, a new optical classification method was constructed based on different water characteristics to classify waters into clear water, phytoplankton-dominated water, and water dominated by phytoplankton and suspended matter together using the thresholds of Rrs490/Rrs560 and Rrs665/Rrs560. The proposed method has a higher classification accuracy compared to other classification methods, and the band-ratio algorithm is simpler and more effective for satellite sensors without NIR bands. Third, given the sensitivity of the empirical method to water variability and the ease of development and implementation, a nonlinear least squares fitted one-dimensional nonlinear function was established based on the selection of the best-fitting spectral indices for different optical water types (OWTs) and compared with other Chl-a estimation algorithms. The validation results showed that the hybrid two-band method had the highest accuracy with squared correlation coefficient, root mean squared difference, mean absolute percentage error, and bias of 0.85, 2.93, 32.42%, and −0.75 mg/m3, respectively, and the results of the residual values further validated the applicability and reliability of the model. Finally, the performance of the classification and estimation algorithms on the four reservoirs was evaluated to obtain images mapping the Chl-a in the reservoirs. In conclusion, this study improves the accuracy of Chl-a estimation for oligotrophic and mesotrophic waters by combining a new classification algorithm with a two-band hybrid model, which is an important contribution to solving the problem of low resolution and high uncertainty in the retrieval of Chl-a in oligotrophic and mesotrophic waters in small- and medium-sized reservoirs and has the potential to be applied to other optically similar oligotrophic and mesotrophic lakes and reservoirs using similar spectrally satellite sensors. [ABSTRACT FROM AUTHOR]

【Objective】 Hybrid snakehead is an important special aquatic fish in China. In order to find out the infection status of hybrid snakehead rhabdovirus (HSHRV), the rhabdovirus disease of hybrid snakehead cultured in the Pearl River Delta was investigated from March 2021 to February 2022.【Method】The parents, fry and water samples of hybrid snakehead were randomly sampled in breeding stage, and these were randomly sampled at fixed time in culture stage and sampled when the outbreak of the virus. A total of 333 samples were collected during the whole monitoring period. Mixed samples of mung bean-sized liver, spleen and kidney were stored in liquid nitrogen for RNA extraction. And reverse-transcribed cDNA was used as template to detect rhabdovirus by real-time fluorescence quantitative PCR (qPCR).【Result】 The main clinical symptoms of rhabdovirus-infected fish were that the fish swam irregularly and spin. Although there was no obvious symptom on the body surface, the liver, spleen, kidney, intestine and swim bladder became red or swollen. The qPCR results revealed that the average positive rate of HSHRV was 13.21%, which was mainly detected from April to November. Among them, the positive rate of samples detected in August was as high as 23.91%. The average positive rate of HSHRV in the culture stage (17.01%) was significantly higher than that in the breeding stage (3.26%). In terms of fish body size, 32.20% of the fry were most susceptible to HSHRV infection within 10 cm, mainly detected from March to September, while 9.52% of the fish of more than 20 cm were least susceptible to HSHRV infection. 【Conclusion】 The positive rates of HSHRV in hybrid snakehead in breeding stage and cultivating stage as well as in different size are determined, which provide references for further understanding the epidemic regularity of hybrid snakehead rhabdovirus disease, with a view to providing data support for the prevention and control of hybrid snakehead rhabdovirus disease. [ABSTRACT FROM AUTHOR]

[Objective] Bisphenol compounds of different origins have been found in many terrestrial ecosystems in across China. Their accurate detection is a key to mitigating their impact on the environment. In this paper, we present an improved method to reliably detect BPs in water and sediment in irrigation districts. [Method] A high-performance liquid chromatography-fluorescence (HPLC-FLD) method was established for simultaneously measuring three types of bisphenol compounds. Suitable pre-treatment method for detecting these compounds was selected from the filtration method and centrifugation method by comparing their efficiency. The tested method was then used to analyze main bisphenol compounds in water and sediment samples taken from vegetable and paddy fields. [Result] The HPLC-FLD can detect BPS when its concentration is not lower than 0.2 µg/L, while for BPF and BPA, the method can detect them when their concentrations are as low as 0.2 µg/L. The centrifugation method can recover 76.69% to 99.03% of the water from the samples, and the detection rate for BPF in ditch water and sediment is 100% and 88.89%, respectively. The greatest BPs concentration the method can detect is 1.45 µg/L for water samples and 587.4 µg/kg for sediment samples. The contents of BPF, BPA and BPS in the sediment samples are 962.95 times, 871.82 times and 72.81 times those in the water samples, respectively. [Conclusion] The centrifugation method works better for pretreating the samples. BPF is the main BPs detected in water and sediment samples taken from the vegetable and paddy fields. BPs in sediments are substantially higher than in water. [ABSTRACT FROM AUTHOR]

The Yangtze River Delta is one of the most economically developed regions on the eastern coast of China. However, a local imbalance currently exists between its water resource environment and economic and social development due to its rapid urbanization. Thus, the reasonable evaluation and protection of local water resources are necessary. This study explores the northern Yangtze Delta, which is a more developed water system, as a pilot area. The temporal and spatial variation characteristics of rainfall and evaporation and their influencing factors were analyzed on the basis of 29 surface water sampling points, 16 rainfall stations, and three evaporation stations in the field from 1956 to 2019. Accordingly, the overall water supply quality of the river basin, the availability of different water resources, and the application of evaluation methods were assessed. Results show that local precipitation and evaporation are characterized by uneven spatial and temporal distributions in local areas, which, in turn, leads to the uneven temporal distribution of runoff, increasing the imbalance between the availability and demand of the limited local water resources. Nevertheless, the overall performance of local water quality is good. Surface water quality is mostly Ⅱ to Ⅲ, and locally Ⅳ. Most noncompliant months are during the non-flood season, and all values exceed the standard permanganate index. Groundwater is Class III or better, and the hydrochemistry type is predominantly calcium bicarbonate, sodium bicarbonate, and magnesium bicarbonate. By exploring the evaluation model of the Yangtze River Delta watershed characteristics, this study aims to provide a helpful reference for extending water resource evaluation in the Yangtze River Delta. Accordingly, this study can promote the sustainable development of the economic and social sectors of the Yangtze River Delta and the construction of its ecological environment. [ABSTRACT FROM AUTHOR]

Understanding the spatiotemporal nitrate retention in streambed is essential for developing management practices in reducing nitrate enrichment. However，the process of nitrate change in the profile of streambed at an elevated nitrate across a watershed scale is still not sufficiently investigated. In this study, we used a combination of hydraulic and hydro‐geochemistry methods to quantify total nitrate retention in streambeds of an agriculture‐intensive watershed in Central China. To conduct surface and groundwater measurements, we collected 1440 water samples for nitrate analysis from 40 shallow drilled wells during the dry and wet seasons from 2018 to 2020. The results showed a clear spatiotemporal variation of nitrate retention in streambed in the watershed. Spatially, nitrate retention in the midstream and downstream reaches was higher than that of the upstream reach. The lowest point of nitrate retention in downstream both in dry and wet seasons was at the depth of 0.75 m. While the lowest nitrate retention was found in midstream and upstream reaches, both in the dry and wet seasons at the depth between 1.5 and 2.5 m. Temporally, nitrate retention was higher in the wet season (1.56 μg N m−2d−1) than in dry season (1.41 μg N m−2d−1). DO min at 3 mg/L was found to the nitrate retention zero threshold in up and midstream. Water change fluxes and nitrate retention both have positive and negative relationship at watershed scale. Nitrate retention at the watershed scale was strongly affected by streambed lithology, precipitation, surface water ‐ groundwater exchange, and human activities. Those findings can provide reference for nitrate removal in international important agricultural areas. [ABSTRACT FROM AUTHOR]

Anthropogenic acidification has become a concerned problem in the Taihu region; however, how it affected the regional weathering rate, especially at the different sub-watershed levels has hardly been studied. To reveal the impact of human activities on watershed weathering and water chemistry in Taihu sub-watersheds, historical water chemistry data (1950s–1970s) and recent water samples (2018–2021) of the local river systems, as well as sediment samples of Taihu lake were collected and analyzed, and a linear addition mass balance method was used to determine the weathering rate at the sub-watershed level. The results indicated that, compared with 60 years ago, the current weathering rate of carbonates and silicates in the Taoge water system (TG) was the highest, reaching 67.2 and 11.4 t·km−2·a−1, increasing by 4.1 and 2.7-folds, respectively; and meanwhile the carbonate and silicate weathering rates increased by 3.1 and 4.9-folds in the Nanhe water system (NH), and 5.2 and 3.4-folds in the Tiaoxi water system (TX), respectively. The increasing rate was significantly correlated to the atmospheric SO2 concentration in different sub-watersheds and was affected by the sub-watershed lithology, e.g., TX had a higher increase rate of silicate weathering due to the wider distribution of silicates in this sub-watershed than the other two. The sediment evidence of Na/K and Ca/Al on the profile in different lake parts, which was influenced by different influx river systems, confirmed that the overall intensity of watershed weathering was higher in TG than in the TX sub-watershed and was higher in the recent decade than 50–60 years ago. The accelerated weathering rate was found to present a definite consistency with the social and economic development in the watershed. Combined analyses of the accelerated weathering rate in the watershed and sedimentation evidence indicated that the major driving force for the watershed weathering has shifted from carbonic acid under the natural condition to human-induced sulfuric acid since 1980s. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Imidacloprid is widely detected in surface water from sub-tropical or tropical agricultural regions of China. However, there is scanty information on the ecological risk assessment of imidacloprid in surface water near tropical crop systems due to the lack of toxicity data on local aquatic organisms. In this study, the acute toxicity risk threshold-hazardous concentration at the 5th percentile of the species (HC5 ) -of imidacloprid to local aquatic organisms in surface water was obtained based on web-interspecific correlation estimation (Web-ICE) and species sensitivity distribution (SSD) models, then its ecological risk assessment in surface water near rice-vegetable practice in Chengmai (Hainan) was temporally and spatially assessed by risk quotient (RQ). The results showed that the risk threshold HC5 of imidacloprid in the aquatic environment around the rice-vegetable rotation in Chengmai is 4.30 μg/L, 41.7% of water samples with the RQ of higher than 1. Also, the RQ values corresponding to the median and maximum concentrations of imidacloprid in surface water from our study were significantly higher than the RQ values in surface water from other regions of China, indicating that imidacloprid residues had higher potential ecological risks to aquatic organisms in surface water from tropical ricevegetable rotation field. In addition, there was the highest potential ecological risk occurring in April, the sowing time (RQ>1 in 92.3% surface water), vegetable planting period (mean RQ=2.53 with RQ>1 with 68% water surface water), and the central regions of Chengmai during the practice of ricevegetable rotation, indicating that there were significant spatiotemporal and crop-related characteristics of the ecological risk of imidacloprid in surface water. It thus contrives to limit and reasonably use imidacloprid by planting period and region in the practice of rice-vegetable rotation in Chengmai, Hainan. [ABSTRACT FROM AUTHOR]

The occurrence, spatial distribution, and source analysis of antibiotics in global coastal waters and estuaries are not well documented or understood. Therefore, the distribution of 14 antibiotics in inflowing river and bay water of Taizhou Bay, East China Sea, was studied. Thirteen antibiotics, excluding roxithromycin (ROM), were all detected in inflowing river and bay water. The total antibiotic concentrations in bay water ranged from 3126.62 to 26,531.48 ng/L, which were significantly higher than those in the inflowing river (17.20–25,090.25 ng/L). Macrolides (MAs) and sulfonamides (SAs) were dominant in inflowing river (accounting for 24.40% and 74.9% of the total antibiotic concentrations, respectively), while SAs in bay water (93.6% of the total concentrations). Among them, clindamycin (CLI) (concentration range: ND–8414 ng/L, mean 1437.59 ng/L) and sulfadimidine (SMX) (ND–25,184.00 ng/L, mean concentrations: 9107.88 ng/L) were the highest in those surface water samples. Source analysis showed that MAs and SAs in the inflowing river mainly came from the wastewater discharge of the surrounding residents and pharmaceutical companies, while SAs in the bay water mainly came from surrounding industrial activities and mariculture. However, the contribution of the inflowing river to the bay water cannot be ignored. The risk assessment showed that SMX and ofloxacin (OFX) have potential ecological risks. These data will support the various sectors of the environment in developing management strategies and to prevent antibiotic pollution. [ABSTRACT FROM AUTHOR]

The photoreduction of mercury (Hg) in clouds is crucial for determining global Hg cycling. The recently-developed isotope approach provides new insight into the fate of atmospheric Hg, however, limited data have been reported on the dynamics of Hg isotopes in clouds. This study presented the isotopic compositions of dissolved mercury (DHg) and particulate mercury (PHg) in cloud water collected at Mt. Tai (1545 m a.s.l.) in eastern China during summer 2021. Both DHg and PHg exhibited positive mass-independent fractionation of odd isotopes (odd-MIF, denoted as Δ199Hg), with averaged Δ199Hg values of 0.83 ± 0.34‰ and 0.20 ± 0.11‰, respectively. This high odd-MIF likely resulted from aqueous photoreduction in clouds, with DHg being more susceptible to photolysis than PHg. Our findings indicated that the photoreduction was promoted by sunlight and influenced by the chemical compositions of cloud water that controlled the Hg(II) speciation. The isotope mixing model estimation revealed that particulate-bound Hg and reactive gaseous Hg constituted the principal sources of Hg in cloud water, accounting for 55% to 99% of the total, while gaseous element Hg also made a notable contribution. Additionally, cloud water samples with faster reduction rates of Hg(II) were located outside of the isotope mixing models, which indicated an enhanced photoreduction process in cloud water. [Display omitted] • Dissolved and particulate Hg (DHg & PHg) isotopes were determined in cloud water. • The odd-MIF value was influenced by the chemical composition of cloud water. • DHg in cloud water showed higher odd-MIF and more pronounced reduction than PHg. • Isotope mixing model showed that Hg(II) dominantly contributed to Hg in cloud water. [ABSTRACT FROM AUTHOR]

This study focused on investigating the concentrations, compositional profiles, partitioning behaviors and spatial variations of organophosphate esters (OPEs) in the Pearl River (PR), South China Sea (SCS) region, to evaluate their environmental risks. ∑OPEs concentrations in the surface water of the PR ranged from 117.5 to 854.8 ng/L in the dissolved phase and from 0.5 to 13.3 ng/L in the suspended particulate matter. In the surface seawaters of the northern and western parts of the SCS, ∑OPEs concentrations were 1.3–17.6 ng/L (mean: 6.7 ± 5.2) and 2.3–24.4 ng/L (mean: 7.6 ± 5.5), respectively. The percentage of chlorinated OPEs in surface water samples from the PR to the SCS was 79 ± 15%. Tripentyl phosphate (TPeP) (average: 28.3%) and triphenylphosphate (TPhP) (average: 9.6%) exhibited significant particulate fraction. A significant negative correlation (p < 0.05) between salt concentration and OPE congeners in seawater suggested that river runoff predominantly introduced OPEs into the coastal waters of the SCS. The findings also showed higher levels of OPEs in the PR and estuary than in offshore waters. The OPE loading from the PR into the SCS was estimated to be ∼119 t y−1. The presence of TCEP (RQ max = 2.1), TnBP (RQ max = 0.48) and TPhP (RQ max = 0.3) in PR water samples pose a high risk to aquatic organisms, whereas OPEs (RQ < 0.1) in SCS water samples do not pose a threat to aquatic organisms. This research emphasizes the environmental fate and impact of OPEs on surface waters of the PR and SCS. [ABSTRACT FROM AUTHOR]

The migration path of formation water plays an indispensable role in hydrocarbon accumulation and preservation. The hydrodynamic field controls the content of various ions in formation water and is an important participant in hydrocarbon evolution. Formation water can basically be used to judge the preservation status of oil/gas reservoirs, especially for carbonate reservoirs; the carbonate reservoirs are a typical example in the Gaoqiao area of the Ordos Basin, China. However, it is not easy to evaluate the sealing and integrity of the gas reservoir because hydrocarbon has experienced a multistage charging process and complicated later reconstruction. The geochemical characteristics of Ordovician formation water (100 brine samples from 67 wells in the Ma5 Member) are studied, and their chemical composition is analyzed in the Ordos Basin. The results show that formation water has high overall salinity and is the original sedimentary water of the carbonate reservoir, which is the sealing reservoir and can promote the accumulation of hydrocarbons. This is also associated with stronger water-rock reactions and diagenetic transformations, such as dolomitization. The main (TDS) range is from 40 to 150 g·L−1, with an average of 66.16 g·L−1; the Cl− content in the formation water samples is the highest, followed by Ca2+, Na+, Mg2+, HCO3−, and SO42−. In addition, the (Cl−-Na+)/Mg2+ ratio, Na+/Cl− ratio, Mg2+/Ca2+ ratio, and S O 4 2 − × 100 / C l − ratio are closely related to gas preservation. The indication function between chemical parameters of formation water and hydrocarbon dynamics can be better understood in carbonate reservoirs by analogy study, so as to improve the accuracy of discriminating favorable hydrocarbon accumulation areas. [ABSTRACT FROM AUTHOR]

In this study, we analyzed the concentration distributions of 20 polycyclic aromatic hydrocarbons (PAHs) in 41 water samples which were collected from the northern part of Taihu Lake during 4 field campaigns (201511, 201606, 201702 and 201709). The concentrations were determined with GC–MS, and their spatial and seasonal distribution characteristics were interpreted. The results show that 2-ring PAHs present considerably higher concentrations in warm seasons than cold seasons, but the concentrations of the other higher-ring PAHs are rather stable in warm and cold seasons. The distribution patterns of these PAHs might be mainly attributed to ambient temperature effects on the PAH solubility in the water body. Meanwhile, the spatial distributions of the PAH concentrations in cold seasons were rather various in the sampling area, while the distributions in the warm seasons were homogeneous. The different distributions could result from the water recharge from the Yangtze River during cold seasons, which diluted PAH concentrations in the northeastern part of the lake. Furthermore, via literature review on PAH concentrations in water body, PAHs are in a wide range of levels and their patterns are different among the studies, which should be more effected by local factors instead of general PAH properties. The results from this study also present special characteristics of PAHs in Taihu Lake, which exhibit more insight on PAHs existence in water bodies. [ABSTRACT FROM AUTHOR]

To understand the characteristics of Vibrio isolates in aquatic environments in China and their public health significance, this study investigated water samples in six cities in China in 2020. A total of 88 sampling locations were included and Vibrio isolates were identified in 81 of them. A total of 143 Vibrio isolates belonging to 16 species were selected for characterization. The population structure of Vibrio species showed great differences among the six cities, indicating regional specificity. The presence of virulence genes was examined for the isolates (n = 78) of five pathogenic Vibrio species. All isolates except one (n = 77) contained at least one virulence gene and isolates belonging to the same species showed very similar virulence gene profiles. Then, 26 isolates from 12 species were examined by multilocus sequence typing and were assigned to 25 STs, of which 24 STs were new. Also, the presence of antibiotic-resistant genes was investigated for all 143 isolates and only three isolates were found to contain genes from aminoglycosides, phenicols, beta-lactams or the tetracycline family. Our results provide valuable insights into the Vibrio community in Chinese aquatic environments and can be applied as guidance for the environmental surveillance of the risk of Vibrio isolates. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Revealing the composition of free-living (FL) and particle-attached (PA) bacterial communities could provide insights into their distinct roles in biogeochemical processes and algal bloom dynamics. While there is still a lack of research about the difference and interactions between FL and PA communities, especially on the Yungui plateau with underestimated diversity. This study unveiled the structure of both FL and PA bacterial communities in a canyon reservoir (Wujiangdu) on the Yungui Plateau, southern China. Water samples were collected from surface water at nine sites in the reservoir. FL and PA bacterial community structures were identified by high-throughput 16S rRNA gene sequencing. We compared the structure and diversity of FL and PA bacteria and investigated their relationship with environmental factors. Results showed that there were different structures between FL and PA bacterial communities, and the dominant FL and PA phyla were affected by different environmental variables. Moreover, diversity of PA bacteria was greater than that of FL bacteria. Both groups exhibited distance decay patterns in this reservoir with varying correlations with geographic distances. FL fraction, however, exhibited a stronger correlation with environmental factors than the PA counterpart. Both FL and PA communities were phylogenetic clustering than expected according to the mean nearest taxon distance. This study provides fundamental information on FL and PA bacteria distribution and demonstrates how specific environmental factors affected these two bacterial fractions in canyon river reservoirs. [ABSTRACT FROM AUTHOR]

In the last decade, the 232Th–230Th system has gained popularity as a tracer to quantify lithogenic sources of trace elements to the marine environment. Thorium (Th) isotopes were utilized to quantify the supply of lithogenic inputs to Keluke Lake and Tuosu Lake in Qaidam Basin, China. A total of 33 water samples were collected from Keluke Lake, Tuosu Lake, and Bayin River to measure the concentrations of dissolved 232Th and 230Th. The relationship of 232Th concentration in the water was in the order Bayin River > Keluke Lake > KLK–TS River > Tuosu Lake, confirming the input of variable lithogenic material sources. Three sources dominate the flux of lithofacies into the lakes: the river input, the deposition of dust and the local input from the sediments surrounding the lakes. On an interannual timescale, the lithogenic flux of Keluke Lake was mainly derived from river input. In summer, the dust flux in the study area could be estimated as 0.133 g/m2/year, while the flux of lithologic material from Bayin River to Keluke Lake was 12.367 g/m2/year. In contrast, the fluvial input to the Tuosu lake was small in comparison to the dust contribution of lithogenic flux. The high Th232-concentration and the vertical sediment flux in this lake may have been caused by resuspension of bottom sediments. [ABSTRACT FROM AUTHOR]

Radon is a naturally emitted gas that is observed in soils, subsoils, air, and all types of water. Because there is a statistically significant association observed between seismic activity and active concentration levels of radon readings, a dissolved form of radon in water near-fault locations such as wells or springs, has significant observational value. Furthermore, as the temperature of the water rises, the dissolved radon in the water might transfer to the air, a process known as degassing. Thus, radon measurements in all types of water such as groundwater, tap waters, and bottled drinking waters have been investigated by covering several aspects of the degassing process, namely, health issues, monitoring volcanic activities, and predicting seismic activities by employing various methods. In this paper, radon measurements of sampled waters removed from the well located at Yishui Seismic Station in China are utilized to monitor the degassing temperature and predict earthquakes. For this purpose, an experiment is devised to collect water samples manually. Then, the amount of radon dissolved in the water samples is examined to find a stable degassing temperature range at Yishui Seismic Station. An experimental setup is constructed to collect data for 20 days. The most important findings found regarding this research can be expressed as follows. (1) When the degassing temperature is observed to be higher than 5°C, the influence on radon value changes greatly. (2) The observations of the radon degassing temperatures in the Yishui well are found to be stable between 18°C and 23°C. [ABSTRACT FROM AUTHOR]

Nonhuman primates (NHPs) are considered an important source of parasitic zoonoses. A study in 2010 revealed high prevalence of Cryptosporidium spp. in free-ranging rhesus monkeys (Macaca mulatta) in a public park in Guiyang, southwestern China, which called for the control of disease in animals and long-term epidemiological tracking of Cryptosporidium spp. After the initiation of a series of public health interventions, we collected 2,402 fecal samples from monkeys and 123 water samples from lakes in the park on six occasions during 2013-2019. They were analyzed and genotyped for Cryptosporidium spp. using PCR and sequence analyses of the small subunit rRNA gene. The C. hominis and C. parvum identified were further subtyped by sequence analysis of the 60 kDa glycoprotein gene. Compared with the high prevalence of Cryptosporidium spp. in fecal samples (10.9% or 45/411) and water samples (47.8% or 11/23) in 2010, only 18 (0.7%) fecal samples and 3 (2.4%) water samples collected in the present study were positive for Cryptosporidium spp., including C. hominis (n = 9) and C. parvum (n = 12). The former belonged to the NHP-adapted IfA17G2R3 subtype, while the latter mostly belonged to rodent-adapted IIpA9. Therefore, the detection rate and genetic diversity of Cryptosporidium spp. during this study period were much lower than those before the public health interventions, and there was a switch from common occurrence of anthroponotic C. hominis subtypes to sporadic occurrence of NHPadapted C. hominis and rodent-adapted C. parvum subtypes. [ABSTRACT FROM AUTHOR]

To analyze the structural characteristics of zooplankton functional groups (ZFGs) and their correlation with environmental physicochemical factors in the Chaohu Lake Basin, water samples were collected from October 2019 to July 2020, and the zooplankton species and ZFGs were investigated. A total of 250 species, including 88 protozoa, 115 rotifers, 28 cladocerans, and 19 copepod species, were detected and divided into 16 ZFGs. The ZFGs exhibited obvious spatiotemporal heterogeneity. ZFGs in the Chaohu Lake were notably different from those in rivers and were different between the rivers. In the ecosystem, network analysis showed that protozoan algae/protozoan bacteria (PA/PB), rotifer particle filter (RF), and rotifer small predator (RSG) were important in the spring, summer, and autumn that and small zooplankton filter (SCF) was important in spring, autumn, and winter, while the importance of other ZFGs changed with seasons. Redundancy analysis showed that the environmental factors with a strong correlation between the ZFG compositions differed in each season. Different ZFGs exhibited different correlations with environmental factors. This study showed that ZFGs were closely related to environmental factors and that functional traits can reflect responses to changes in the water environment. [ABSTRACT FROM AUTHOR]

Diffusion flux is an essential tool to estimate the contribution of internal nitrogen and phosphorus in eutrophic lakes. There are mainly two methods, i.e., model calculation based on in-situ porewater sampling and water quality monitoring in laboratory incubation. The results obtained by the two methods are rarely compared, decreasing the validity of internal contribution and following management strategies. In this study, sediment samples were collected from a lake in China, then the fluxes were estimated by model calculation and laboratory incubation. The results show that there is an order of magnitude difference in the fluxes measured by these two methods. The mean values of ammonia (NH4+-N) and soluble reactive phosphate (SRP) obtained from the model calculations were 24.4 and 1.30, respectively. The mean values of NH4+-N and SRP obtained in the undisturbed group of sediment incubation were 7.84 and 5.47, respectively, and in the disturbed group of sediment incubation were 16.2 and 4.06, respectively. Sediment incubation is a combination of multiple influencing factors to obtain fluxes, while porewater model is based on molecular diffusion as the theoretical basis for obtaining fluxes. According to the different approaches of the two methods, sediment incubation is recommended as a research tool in lake autochthonous release management when the main objective is to remove pollution, while the porewater model is recommended as a research tool when the main objective is to control pollution. When assessing the diffusive flux of nitrogen, it is recommended to choose the stable form of total dissolved nitrogen to discuss the flux results. [ABSTRACT FROM AUTHOR]

Total suspended matter (TSM) has a crucial impact on light propagation in the water column, and often co-varies with nutrients, heavy metal and micropollutant fluxes. The objective of this study was to explore the feasibility of mapping TSM in lakes (area > 1 ha) across China using Landsat surface reflectance product embedded in Google Earth Engine. We conducted 44 sampling campaigns at 423 natural and manmade lakes across China, and determined TSM from 2036 water samples collected during 2011–2020. Landsat surface reflectance was matched with water sampling events within ±7 days of satellite overpasses, yielding 1908 matched pairs. We divided the TSM dataset into nine subsets, with eight subsets dedicated to building of simple regression and Random Forest (RF) models, and the remaining subset used to validate model performance. Regression analysis indicated strong associations between TSM concentration and both the Red band (Band 4; R2 = 0.76, RMSE = 21.4 mg/L) and the suspended matter index [(Nir + Red)/2); R2 = 0.71, RMSE = 17.1 mg/L]. The RF model outperformed the Red band model as indicated by higher coefficient of determination for model calibration (R2 = 0.95) and validation (R2 = 0.81). We also assembled samples (N = 1703) from lakes in different continents, and both the RF (RMSE = 16.04 mg/L) and Red band (RMSE = 18.9 mg/L) models exhibited acceptable performance. The models were further evaluated using a time series of TSM records from six large lakes in the USA and Japan (in situ TSM collected during 1988–2018). Finally, we used 460 scenes of Landsat/OLI images mainly acquired in 2019 to map TSM in lakes across China. Results showed considerable regional variability (TSM range: 0.12–860 mg/L), with lakes in Northeast China (44.6 mg/L), East China (38.8 mg/L) and Xinjiang-Inner Mongolia (39.7 mg/L) exhibiting much higher TSM concentration than lakes in the Yungui Plateau (17.62 mg/L) and the Tibetan Plateau (5.31 mg/L). Results confirmed the stability and spatial transferability of both models. Given the relationships among TSM and various indicators (e.g. nutrients, water clarity, chlorophyll-a) of the trophic state of aquatic ecosystems, these models would greatly facilitate TSM monitoring in lakes, and provide water resources managers with additional tools to assess the impact of water protection measures. [ABSTRACT FROM AUTHOR]

• UV-327 was the major traditional BZT-UVs in surface water from TL and QR. • A characteristic fragment ion-based strategy was developed to screen unknown BZT-UVs. • Seven novel BZT-UVs were discovered in surface water from TL and QR. • Four novel BZT-UVs were further confirmed with their native standards. The comprehensive understanding of the occurrence of benzotriazole UV stabilizers (BZT-UVs) in environmental surface water is imperative due to their widespread application and potential aquatic toxicity. We conducted an analysis of 13 traditional BZT-UVs in surface water samples collected from Taihu Lake (TL, n = 23) and Qiantang River (QR, n = 22) in China. The results revealed that 5‑chloro-2-(3,5-di-tertbutyl-2-hydroxyphenyl)-benzotriazole (UV-327) was consistently the predominant BZT-UV in water samples from TL (mean 16 ng/L; detection frequency 96 %) and QR (14 ng/L; 91 %). Furthermore, we developed a characteristic fragment ion-based strategy to screen and identify unknown BZT-UVs in collected surface water, utilizing a high-resolution mass spectrometer. A total of seven novel BZT-UVs were discovered in water samples, and their chemical structures were proposed. Four of these novel BZT-UVs were further confirmed with standards provided by industrial manufacturers. Semi-quantitative analysis revealed that among discovered novel BZT-UVs, 2-(2‑hydroxy-3‑tert‑butyl‑5-methylphenyl)-benzotriazole was consistently the predominant novel BZT-UV in TL (mean 4.1 ng/L, detection frequency 70 %) and QR (2.8 ng/L, 77 %) water. In TL water, the second predominant novel BZT-UV was 2-(3-allyl-2‑hydroxy-5-methylphenyl)-2H-benzotriazole (mean 3.9 ng/L,

• Revealed the distribution characteristics of hydrochemical processes in the central depression of the Songliao Basin. • Elucidated the enrichment patterns of Type B typical moderate-to-low temperature sedimentary basins in Northeast China. • Unveiled the inhibitory effects of feldspar dissolution and desulfurization on B concentration. • Summarized the origins and influencing factors of boron (B) concentration in different geothermal systems. • Provided new insights into the factors affecting B concentration. The presence of boron (B) in geothermal water is prevalent and detrimental to the growth and utilization of geothermal resources. The Songliao Basin is a typical sedimentary basin-type geothermal system characterized by elevated B concentrations and an abundance of geothermal resources. However, the precise origins, pathways, and mechanisms of B enrichment in the basin are still unknown, which limits the development and utilization of geothermal energy effectively. This study collected 468 geothermal water samples from the Quantou Formation in the central depression of the southern Songliao Basin. The origins and drivers of B in the catchment were examined by integrating the results of the hydrochemical analysis and neural network classification with those of prior research. This study examined the variables that impact the concentration of boron (B) in groundwater through the implementation of an innovative approach. Firstly, the distribution characteristics of hydrochemical processes were analyzed in the study area. After that, through the manipulation of variables, the effects of various hydrochemical processes on the concentration of B were investigated, resulting in the identification of the underlying mechanism accountable for the enrichment of B. The results showed that B primarily originates from geothermal water, and its passage into aquifers is facilitated by prolific fractures. B experiences mixing and dilution events as it ascends from the groundwater. High concentrations of B are primarily found in areas with elevated total dissolved solids levels. Furthermore, the presence of kaolinite resulting from feldspar dissolution in geothermal water diminishes B concentration, while the desulfurization process indirectly inhibits the enrichment of B in the study area. This work can contribute to a better comprehension of the sources of B in sedimentary basin-type geothermal systems and its patterns of enrichment. Additionally, it can guide the development and application of geothermal resources in these environments. [ABSTRACT FROM AUTHOR]

Terrestrial silicon (Si) from biogeochemically weathered rocks and soils into oceans must pass through several water bodies, resulting in some Si immobilized. Hence, the knowledge on Si distribution characteristics in different water bodies at a basin scale is helpful to understand Si immobilization. A total of 65 surface sediments and corresponding overlying water samples were sampled from six water bodies (Dianchi Lake, DL; Dadu River, DR; Tuojiang River, TR; Honghu Lake, HL; Donghu Lake, DhL; Taihu Lake, TL) in the Yangtze River Basin of China, total dissolved Si (TDSi) in overlying water and exchangeable Si (Ex-Si), active non-biogenic Si (NBSi), and total acid dissolved Si (TADSi) in sediments were analyzed. Water chemical parameters (pH, EC, and TDP) and sediment components (LOI, TN, TP, and TADFe) showed that the water environment characteristics of six water bodies differed. TDSi differed among regions and between lakes and rivers, significantly higher in water bodies in the upper reaches and rivers than the middle or lower reaches and lakes (p < 0.05), respectively. Ex-Si in sediments in the upper reaches was significantly higher than in the middle or lower reaches (p < 0.05), except for DhL, whose Ex-Si was the highest. Mean TADSi and active NBSi were significantly higher in lakes than rivers (p < 0.05). Oxidation of sediments significantly increased TDSi in overlying water and active NBSi in sediments (p < 0.01). Si forms in six water bodies significantly depended on components of the sediments (e.g. active Ca2+, Mg2+, Fe, and Al3+) and water chemical parameters (p < 0.05). Our results suggest that immobilization of Si in water bodies in the Yangtze River Basin depends on the types of water bodies and sediments, lakes and Fe–Al dominated sediments have a high potential to immobilize Si, but anthropogenic interference should not be ignored. • TDSi in overlying water in upper reaches was higher than middle or lower reaches. • Exchangeable Si in upper reaches sediments was higher than middle or lower reaches. • TADSi and active non-biogenic Si in sediments in lake were higher than river. • Ca–Mg-dominated sediments had lower capacity to immobilize Si than Fe–Al-dominated. [ABSTRACT FROM AUTHOR]

Microorganisms are integral to freshwater ecological functions and, reciprocally, their activity and diversity are shaped by the ecosystem state. Yet, the diversity of bacterial community and its driving factors at a large scale remain elusive. To bridge this knowledge gap, we delved into an analysis of 16S RNA gene sequences extracted from 929 water samples across China. Our analyses revealed that inland water bacterial communities showed a weak latitudinal diversity gradient. We found 530 bacterial genera with high relative abundance of hgcI clade. Among them, 29 core bacterial genera were identified, that is strongly linked to mean annual temperature and nutrient loadings. We also detected a non-linear response of bacterial network complexity to the increasing of human pressure. Mantel analysis suggested that MAT, HPI and P loading were the major factors driving bacterial communities in inland waters. The map of taxa abundance showed that the abundant CL500-29 marine group in eastern and southern China indicated high eutrophication risk. Our findings enhance our understanding of the diversity and large-scale biogeographic pattern of bacterial communities of inland waters and have important implications for microbial ecology. [Display omitted] • Inland water bacterial communities showed a weak latitudinal diversity gradient. • Bacterial network complexity exhibited humped patterns as HPI increasing. • Bacterial community composition depended on temperature, nutrient loading, and HPI. • HgcI clade is highly abundant and widely distributed in inland waters. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is a protozoan parasite, causing one of the most prevalent parasitic infections in the world. In the present study water sources of the Qinghai-Tibet Plateau (QTP), China, where the hygienic infrastructure is still developing, were investigated. A total of 214 water samples of 10 L volume, were collected from wastewater treatment plants (WWTPs), a slaughterhouse and rivers. The samples were filtered and then analysed using real-time PCR and multilocus genotyping. T. gondii DNA was found in four (1.9%) samples representing T. gondii type I; in one of them T. gondii-like oocysts were also confirmed microscopically. The approximate level of contamination of positive samples ranged between 30 and 2300 T. gondii sporozoites. The results of this study confirmed that T. gondii is present in wastewater in the greater metropolitan area of Xining and a neighbouring county. Contamination of wastewater at this level constitutes rather a moderate source of Toxoplasma infections in humans and animals. It suggests, however, a link between environmental exposure of animals, meat processing facilities and WWTPs. To our knowledge, this is the first investigation describing T. gondii detection in wastewater and environmental water samples collected from the territory of P.R. China using sensitive molecular tools. [ABSTRACT FROM AUTHOR]

The hydrogeological conditions in the North China type coal mine area are complex and diverse, and water gushing accidents are frequent. Quickly and accurately identifying the source of water in these incidents is necessary to reduce the harmful effects of mine floods. Taking the Pingdingshan mining area as an example, what chemical composition data from each of the main aquifers was collected and a mine gushing water source model, based on Hierarchical Cluster Analysis—Principle Component Analysis—Entropy Weighted Membership (HCA‐PCA‐EWM), was established. First, typical water sample data from an aquifer were selected by systematic cluster analysis. Then, the remaining water samples were randomly divided into training and prediction samples. Principal component analysis was used to reduce the dimension of water chemical components in training samples. Finally, the discriminant model of the water gushing source was established on the basis of the entropy weight‐membership degree principle. The accuracy of the HCA‐PCA‐EWM discriminant model approached 100%, while those of traditional PCA‐Fisher and PCA‐EWM discriminant models were 62.5 and 87.5%, respectively. From the above, the HCA‐PCA‐EWM discriminant model can effectively select typical aquifer water samples, significantly improve the accuracy of the model, and provide a theoretical basis for the effective identification of mine water gushing sources. [ABSTRACT FROM AUTHOR]

To clarify the enrichment characteristics of uranium and radon in deep-buried geothermal water, 39 geothermal water samples with a buried depth of more than 800 m in the Kaifeng geothermal system in China were collected. According to the test results of uranium concentration, radon activity and other conventional chemical indicators of the water samples, the source of uranium and radon in geothermal water was obtained. Also, the influence of the redox environment, temperature and hydrochemical parameters on the occurrence characteristics of uranium and radon was analyzed. This study has indicative significance to the migration of geothermal water. [ABSTRACT FROM AUTHOR]

Bentazone is a widely used post-emergence herbicide, while no data was available on its concentrations in tap water from China and in urine among the general population. It was determined in the source (Wuhan section of the Yangtze River watershed), treated, and tap water (n = 20, 20, and 170, respectively) in different seasons (2019) in Wuhan, central China. Also, urine samples (n = 38) collected from healthy adults in Wuhan (September 2020) were analyzed to characterize its urinary concentration. Bentazone was detected in all the source and treated water samples. Its concentrations in the source water in July were higher than those in February (median: 17.9 ng/L vs. 2.86 ng/L) (p < 0.05). It cannot be removed efficiently (27.8–27.9%) by conventional drinking water treatment using NaClO, but it can be efficiently removed by using chlorine dioxide or ozone combined with activated carbon. Bentazone was frequently detected (detection frequency: 96.3%) in 160 tap water samples (underwent conventional treatment) (median: 1.95 ng/L, range: <0.02–47.0 ng/L), while it was not detectable in tap water samples that underwent ozone combined with activated carbon. Seasonal variations were found, with the lowest median concentration (ng/L) in April (0.46) and the highest in July (17.6). In addition, bentazone was frequently (92.1%) detected in human urine samples (median: 0.02 ng/mL; range: < 0.01–0.11 ng/mL). The estimated daily intake of bentazone based on its median concentration in tap water (0.04 ng/kg-body weight [bw]/day) accounted for approximately 8% of that based on the median urinary concentration (0.48 ng/kg-bw/day). This is the first time to characterize its occurrence in drinking water from China and its occurrence in the urine of the general population. [ABSTRACT FROM AUTHOR]

In the petroleum industry, Sulin classification has been adopted for the classification of formation water, i.e. four types of formation water, including Na2SO4, NaHCO3, MgCl2 and CaCI2. In production practice, Sulin classification not only does not cover NaCl, Ca(HCO3) 2 and other common water types, but also ignores the directional role of some dominant ions in water type evaluation, resulting in the confusion of water type classification of surface water and formation water. According to the affinity of 8 common ions in water, formation sequence of salt compounds, millimolar concentration ratio of ions unit charge, comprehensive genetic coefficient of natural water and comprehensive judgment coefficient of natural water, the natural water is divided into five categories and twenty ions combination types. Combined with NaCl unit charge millimolar fraction, dominant ions and dominant salt, and based on the basic principle for naming the natural water type, the salt formed by the equivalent unit charge ion with weaker affinity is dominant. T he natural water type is divided into nine water types by classification method with nine types and six steps, including NaCl, Na2SO4, MgCl2, NaHCO3, CaCl2, MgSO4, CaSO4, Mg( HCO3) 2 and Ca(HCO3)2 • According to the analysis and verification of 146 water samples in China and abroad, the results show that the distinction methods of five common formation water types and four common surface water types are universal; fresh water is mainly the most unstable Ca( HCO3) 2 type divided by classification method with nine types and six steps, rather than Na2 SO 4 type classified by Sulin classification; various water types are closely related to geological environment and its evolution history. [ABSTRACT FROM AUTHOR]

Mo5N6 nanosheets were synthesized by a nickel-induced growth method and were found to possess peroxidase-like activity in acidic condition and catalase-like activity in weak basic condition. In acidic condition, Mo5N6 nanosheets can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2 to form a blue color product (TMBOX). At the co-existence of 4-aminophenol (4-AP), 4-AP can react with H2O2 and TMBOX, resulting in the decrease of TMBOX and the fading of blue color. Therefore, a facile, sensitive colorimetric method for the quantitative detection of 4-AP was developed. The linear range for 4-AP was 1.0 to 80.0 μmol⋅L‒1 (R2 = 0.999), and the detection limit was 0.56 μmol⋅L‒1 based on 3σ/k. Resorcinol, aniline, humic acid, and common ions and anions in surface water did not interfere the determination of 4-AP. This colorimetric method was applied to measure the 4-AP in real water sample from Wulong River in Fujian Province of China. The relative standard deviation for the determination of 4-AP was ranged from 0.03 to 1.88%, and the recoveries from spiked samples were ranged between 99.2 and 107.6%. The determination results were consistent with those obtained by HPLC. [ABSTRACT FROM AUTHOR]

Much more attention has been poured into microplastic pollution in freshwater systems recently. In the present study, the pollution of microplastics (MPs) in surface water and freshwater fish (crucian carp, etc.) were investigated from Gehu Lake, which is the second largest lake in southern Jiangsu after Taihu Lake. The result manifested that the average abundance of MPs was respectively 6.33±2.67 n/L for surface water and 10.7 items per individual for freshwater fish. The distribution of MPs in Gehu Lake varied from place to place, with the highest abundance of MPs was observed in the two estuaries of the eastern part of the lake. It was speculated that topographical factors and human factors were the main factors affecting the abundance and distribution of MPs. Transparent fibers were the main type of MPs in water samples, accounting for 69.70% of all detected particles. Meanwhile, most of the MPs ingested by freshwater fish were fibers, and the main colors were transparent and blue. In addition, the dominant size of the MPs was between 0.1 to 0.5 mm in water and fish samples. Moreover, PES, man-made fiber, and PP were the dominant polymer types in the surface water and fish samples. The results of this investigation can provide basic data for the research and management of MPs in freshwater systems. [ABSTRACT FROM AUTHOR]