Multi-Emission Carbon Dots Combining Turn-On Sensing and Fluorescence Quenching Exhibit Ultrahigh Selectivity for Mercury in Real Water Samples.

Mercury is a ubiquitous heavy-metal pollutant and poses serious ecological and human-health risks. There is an ever-growing demand for rapid, sensitive, and selective detection of mercury in natural waters, particularly for regions lacking infrastructure specialized for mercury analysis. Here, we show that a sensor based on multi-emission carbon dots (M-CDs) exhibits ultrahigh sensing selectivity toward Hg(II) in complex environmental matrices, tested in the presence of a range of environmentally relevant metal/metalloid ions as well as natural and artificial ligands, using various real water samples. By incorporating structural features of calcein and folic acid that enable tunable emissions, the M-CDs couple an emission enhancement at 432 nm and a simultaneous reduction at 521 nm, with the intensity ratio linearly related to the Hg(II) concentration up to 1200 µg/L, independent of matrix compositions. The M-CDs have a detection limit of 5.6 µg/L, a response time of 1 min, and a spike recovery of 94 ± 3.7%. The intensified emission is attributed to proton transfer and aggregation-induced emission enhancement, whereas the quenching is due to proton and electron transfer. These findings also have important implications for mercury identification in other complex matrices for routine, screening-level food safety and health management practices.

[Hydrochemical Characteristics and Pollution Source Identification of Groundwater in Plain Area of Barkol-Yiwu Basin].

Groundwater is an important water supply source for production and life in arid and semi-arid areas. This study revealed the hydrochemical characteristics of groundwater in the Barkol-Yiwu Basin of Xinjiang and analyzed the pollution sources, which is of great significance in the sustainable utilization of local groundwater. Four spring water samples, 20 unconfined groundwater samples, and 11 confined groundwater samples collected in August 2022 were analyzed using mathematical statistics, a graphic method, and the PCA-APCS-MLR model. The results showed that the chemical types of groundwater in the study area were complex and diverse. The spring water was mainly HCO3·SO4-Na·Ca type groundwater, the chemical types of unconfined groundwater were mainly HCO3·SO4-Na·Ca and HCO3·SO4-Ca, and the chemical types of confined groundwater were HCO3·SO4-Na·Ca and HCO3·Cl·SO4-Na·Ca. The hydrochemical type of confined water in unused land was single(Cl·SO4-Na·Ca), and the hydrochemical types of confined groundwater in cultivated land and urban and rural residential land were complex, indicating that groundwater was affected by human activities. The evolution process of groundwater was mainly affected by water-rock interactions and cationic exchange. The cation exchange from spring water to unconfined groundwater to confined groundwater was gradually enhanced, the weathering and dissolution of gypsum and anhydrite was gradually weakened, and the weathering and dissolution of rock salt was gradually strengthened. Leaching-enrichment(mainly the dissolution of evaporite), human activities(industrial, agricultural, and domestic pollution), and the primary geological environment were the main factors affecting groundwater in the study area.

Hydrogeochemical evidence for fluoride sources and enrichment in desert groundwater: A case study of Cherchen River Basin, northwestern China.

The identification of fluoride (F-) sources and enrichment mechanisms is imperative to understand the multiple fluorine (F) pathways, and further, to control regional diffuse F- contamination in groundwater. However, the factors that control high-F- groundwater are not fully understood in desert climate regions. Hence, a sampling campaign was conducted from 71 desert groundwater sites and six river water sites in the Cherchen River Basin (CRB), northwestern China. This study combined hydrochemical compositions with an optimized forward model, with the aim of determining the potential sources and enrichment mechanisms in F--contaminated desert groundwater. Approximately 58.46% of the samples had F- concentrations over the national standard of 1.0 mg/L. More severe F- contamination was found in the multi-layered structured confined aquifer (MCA) of the alluvial plain (1.42 ± 1.11 mg/L). The primary contributors of desert groundwater F- were the dissolution of F-bearing minerals containing evaporite (∼58.80%), silicate (∼15.89%), and carbonate (∼12.94%), followed by the river water input (∼12.08%). In contrast, anthropogenic activities (∼0.16%) and precipitation contributed less to desert groundwater F-. The dissolution equilibrium of CaF2 was important for F- enrichment in desert groundwater. Compared with the piedmont plain, intensive evaporation and salinization were more conducive to F- enrichment in the alluvial plain. Under alkaline condition, the dissolutions of evaporite and fluorite allowed extra F- to release into desert groundwater when Ca2+ and Mg2+ were up to oversaturation. Moreover, the desorption of F- was promoted by competitive adsorption of OH- and HCO3-, and the adsorption capacity of F- was weakened by cation exchange of K++Na+ with Ca2++Mg2+. As a result, desert groundwater had a higher concentration of F- in the alluvial plain. Our study provided a comprehensive understanding of multiple F pathways in desert groundwater. This study also highlights the effect of hydrogeochemical background on high-F- desert groundwater.

[Assessment of Groundwater Contamination Risk in the Plain Area of Southern Turpan Basin].

Groundwater contamination risk assessment is an effective tool for groundwater pollution prevention and control. The evaluation system mainly includes three parts:groundwater contamination source load assessment, groundwater vulnerability assessment, and groundwater function value evaluation. Taking the plain area of southern Turpan Basin as an example, based on the survey data and land use data, point source pollution and non-point source pollution were divided to evaluate the load of groundwater pollution sources, the classical DRASTIC model was selected to evaluate the vulnerability of groundwater, and the functional value of groundwater was evaluated from the point of view of water quality and quantity. The three factors were weighted and superimposed via GIS platform to generate the risk zoning map of groundwater contamination. The results showed that the overall risk of groundwater contamination in the study area was low. The area of high-risk and relatively high-risk areas accounted for 15.5% of the total study area, which were mainly distributed in L1, L2, and L3 of the study area. L1 was mainly affected by high pollution source load and high groundwater vulnerability. L2 was mainly the result of the joint action of high groundwater function value and domestic non-point source pollution. Non-point source pollution dominated by agricultural activities and high functional value of groundwater were the main reasons for the high risk of groundwater pollution in the L3 area. The results of the groundwater contamination risk assessment serve as an important reference for decision-makers to delineate the prevention and control area of groundwater pollution.

Identification and Risk Assessment of Priority Control Organic Pollutants in Groundwater in the Junggar Basin in Xinjiang, P.R. China.

The Junggar Basin in Xinjiang is located in the hinterland of Eurasia, where the groundwater is a significant resource and has important ecological functions. The introduction of harmful organic pollutants into groundwater from increasing human activities and rapid socioeconomic development may lead to groundwater pollution at various levels. Therefore, to develop an effective regulatory framework, establishing a list of priority control organic pollutants (PCOPs) is in urgent need. In this study, a method of ranking the priority of pollutants based on their prevalence (Pv), occurrence (O) and persistent bioaccumulative toxicity (PBT) has been developed. PvOPBT in the environment was applied in the screening of PCOPs among 34 organic pollutants and the risk assessment of screened PCOPs in groundwater in the Junggar Basin. The results show that the PCOPs in groundwater were benzo[a]pyrene, 1,2-dichloroethane, trichloromethane and DDT. Among the pollutants, benzo[a]pyrene, 1,2-dichloroethane and DDT showed high potential ecological risk, whilst trichloromethane represented low potential ecological risk. With the exception of benzo[a]pyrene, which had high potential health risks, the other screened PCOPs had low potential health risks. Unlike the scatter distribution of groundwater benzo[a]pyrene, the 1,2-dichloroethane and trichloromethane in groundwater were mainly concentrated in the central part of the southern margin and the northern margin of the Junggar Basin, while the DDT in groundwater was only distributed in Jinghe County (in the southwest) and Beitun City (in the north). Industrial and agricultural activities were the main controlling factors that affected the distribution of PCOPs.

Human infection of avian influenza A H3N8 virus and the viral origins: a descriptive study.

BACKGROUND: The H3N8 avian influenza virus (AIV) has been circulating in wild birds, with occasional interspecies transmission to mammals. The first human infection of H3N8 subtype occurred in Henan Province, China, in April, 2022. We aimed to investigate clinical, epidemiological, and virological data related to a second case identified soon afterwards in Hunan Province, China. METHODS: We analysed clinical, epidemiological, and virological data for a 5-year-old boy diagnosed with H3N8 AIV infection in May, 2022, during influenza-like illness surveillance in Changsha City, Hunan Province, China. H3N8 virus strains from chicken flocks from January, 2021, to April, 2022, were retrospectively investigated in China. The genomes of the viruses were sequenced for phylogenetic analysis of all the eight gene segments. We evaluated the receptor-binding properties of the H3N8 viruses by using a solid-phase binding assay. We used sequence alignment and homology-modelling methods to study the effect of specific mutations on the human receptor-binding properties. We also conducted serological surveillance to detect the H3N8 infections among poultry workers in the two provinces with H3N8 cases. FINDINGS: The clinical symptoms of the patient were mild, including fever, sore throat, chills, and a runny nose. The patient's fever subsided on the same day of hospitalisation, and these symptoms disappeared 7 days later, presenting mild influenza symptoms, with no pneumonia. An H3N8 virus was isolated from the patient's throat swab specimen. The novel H3N8 virus causing human infection was first detected in a chicken farm in Guangdong Province in December, 2021, and subsequently emerged in several provinces. Sequence analyses revealed the novel H3N8 AIVs originated from multiple reassortment events. The haemagglutinin gene could have originated from H3Ny AIVs of duck origin. The neuraminidase gene belongs to North American lineage, and might have originated in Alaska (USA) and been transferred by migratory birds along the east Asian flyway. The six internal genes had originated from G57 genotype H9N2 AIVs that were endemic in chicken flocks. Reassortment events might have occurred in domestic ducks or chickens in the Pearl River Delta area in southern China. The novel H3N8 viruses possess the ability to bind to both avian-type and human-type sialic acid receptors, which pose a threat to human health. No poultry worker in our study was positive for antibodies against the H3N8 virus. INTERPRETATION: The novel H3N8 virus that caused human infection had originated from chickens, a typical spillover. The virus is a triple reassortment strain with the Eurasian avian H3 gene, North American avian N8 gene, and dynamic internal genes of the H9N2 viruses. The virus already possesses binding ability to human-type receptors, though the risk of the H3N8 virus infection in humans was low, and the cases are rare and sporadic at present. Considering the pandemic potential, comprehensive surveillance of the H3N8 virus in poultry flocks and the environment is imperative, and poultry-to-human transmission should be closely monitored. FUNDING: National Natural Science Foundation of China, National Key Research and Development Program of China, Strategic Priority Research Program of the Chinese Academy of Sciences, Hunan Provincial Innovative Construction Special Fund: Emergency response to COVID-19 outbreak, Scientific Research Fund of Hunan Provincial Health Department, and the Hunan Provincial Health Commission Foundation.

Spatial distribution, source apportionment and health risk assessment of inorganic pollutants of surface water and groundwater in the southern margin of Junggar Basin, Xinjiang, China.

Surface water (SW) and groundwater (GW) are crucial water supply sources in the southern margin of Junggar Basin in Xinjiang. The sources of toxic components in SW and GW and their negative effects on human health are of great concern. A total of 40 SW and 596 GW samples were collected at the oasis belt to analyze distribution, sources and potential health risks of inorganic pollutants in SW and GW. Results revealed that SW quality was severely affected by Hg, 30.0% of which had Hg concentration greater than the national drinking water standard. High Hg SW was mainly distributed near Manas County and Urumqi City. GW quality was mostly affected by SO42-, 24.7% of which had SO42- concentration greater than the national drinking water standard. High SO42- GW primarily occurred in the northwest and middle of the study area. Source apportionment of inorganic pollutants identified geological background, municipal wastewater disposal, water-rock interaction, geological environment, geological structure and industrial emission were the prominent potential sources of inorganic pollution in SW, with contribution rates of 1.2%, 10.0%, 43.6%, 35.1%, 6.3% and 3.8%, respectively. Five potential pollution sources in GW (including geological background, municipal wastewater disposal, water-rock interaction, geological environment and aquifer burial depth) were identified, with contribution rates of 0.7%, 9.6%, 77.6%, 11.1% and 1.0%, respectively. Probabilistic health risk assessment showed that Cl- and As in SW and GW were the main inorganic pollutants threatening human health. Non-carcinogenic risks for adults and children were negligible, while carcinogenic risks cannot be negligible. Furthermore, the contribution of potential pollution sources to health risks was quantified using positive matrix factorization coupling with health risk assessment model. Based on which, we offered the suggestion that water quality improvement in contaminated areas should be implemented in combination with pollution monitoring systems.

Hydrogeochemical characteristics and groundwater quality assessment in the plain area of Yarkant River Basin in Xinjiang, P.R. China.

The deteriorating groundwater quality due to natural genesis and anthropogenic activities has prevented the sustainable use of groundwater. The characteristics and factors affecting groundwater quality for drinking in shallow aquifers (depth ≤ 100 m) in the plain area of Yarkant River Basin in Xinjiang were analyzed using water quality index (WQI), geostatistics, and geochemical methods. Results showed that the groundwater was weak-alkaline with neutral pH, with dominant water types being SO4•HCO3-Ca•Mg, SO4•Cl•HCO3-Na•Ca, SO4•HCO3•Cl-Ca•Na, Cl•SO4-Na•Ca, and HCO3•SO4-Mg•Ca. WQI ranged between 31.79 and 549.37, and about 14.43%, 31.96%, 18.56%, 22.68%, and 12.37% of the all samples were excellent, good, medium, poor, and extremely poor quality, respectively. The proportion of excellent quality was the highest in single structure phreatic aquifer (SSPA, 50.00%) and good quality were the highest in multilayered structure phreatic aquifer (MSPA, 34.21%) and multilayered structure confined aquifer (MSCA, 28.89%). With the extension of the river, the groundwater quality gradually degenerated from south to north in phreatic aquifer (PA, including SSPA and MSPA). The further away from the Yarkant river, the worse the groundwater quality of PA. Furthermore, the WQI showed excellent, good, and an alternation of medium and poor quality (including extremely poor quality) from south to north in the MSCA. The groundwater quality deterioration might have been affected by the dissolution of evaporite minerals, such as halite, gypsum, and anhydrite and ion exchange process. In addition, local effects of anthropogenic activities and land usage patterns on the groundwater quality should be reckoned as well.

Heavy metal pollution and health risk assessment of agricultural land in the Southern Margin of Tarim Basin in Xinjiang, China.

The study aimed to analyze the level of heavy metal pollution in the agricultural lands in the southern margin of Tarim Basin, Xinjiang, and its risks to human health. A total of 1765 soil samples were collected from the Cele-Ruoqiang area. The contents of soil As, Cd, Cr, Cu, Hg, Ni, Pb and Zn were analyzed using the pollution load index method. The results showed that soil was slightly contaminated with Hg and Cd; the multivariate statistical analysis indicated that Cr, Ni, As, Cu, Zn, and Cd were formed mostly by geochemical genesis, whereas Hg and Pb contents by the geological origin and human activities. The health risk assessment showed that there is no unacceptable non-carcinogenic health risk. As levels posed carcinogenic risk, however, they were within human tolerance. Thus, this study provides a scientific basis for local agricultural production safety and prevention and control of soil heavy metal pollution.

Hand, foot, and mouth disease in Changsha City, China, 2009-2017: a new method to analyse the epidemiological characteristics of the disease.

Objectives: By adopting a new method, this study aimed to analyse the epidemiological characteristics of hand, foot, and mouth disease (HFMD) in nine districts and counties (cities) of Changsha City, China, from 2009 to 2017.Methods: The reported HFMD cases were collected in Changsha from 2009 to 2017. The traditional descriptive method and a new method (index system) including six indices (richness index N, Simpson diversity index D, Shannon diversity index H, Berger-Parker dominance index d, Shannon evenness index E, and Morisita-Horn similarity index C) were used to describe the epidemiological characteristics of HFMD in Changsha.Results: There were 214155 HFMD reported in Changsha during the study period. The incidence of the disease was higher in even-numbered years (2010, 2012, 2014, and 2016) than in uneven-numbered years (2009, 2011, 2013, 2015, and 2017), with two peaks in May to June and October to November every year. The age of onset was mainly from 0 to 5 years old, and the death was mainly from 0 to 2 years old. According to occupational classification, districts and counties (cities) had a high degree of similarity of the composition of HFMD, and there was no regional difference.Conclusions: Changsha had a yearly increasing trend of HFMD from 2009 to 2017, and the key population for prevention and control was children aged in 0-5 years old. Seasonal distribution of high incidence and peak incidence were occurred in even-numbered years. The sub-regions of the city shared moderate diversity and high similarity of occupational distribution of HFMD.

Characteristics and compound-specific carbon isotope compositions of sedimentary lipids in high arsenic aquifers in the Hetao basin, Inner Mongolia.

Organic matter, as an electron donor, plays a vital role in As mobilization mediated by microorganisms during reductive dissolution of Fe/Mn oxides in shallow aquifers. However, the specific types and sources of organic matter involved in biogeochemical processes accelerating As mobilization are still controversial. Both sediment and groundwater samples were collected at different depths from aquifers of the Hetao Basin, a typical inland basin hosting high As groundwater. Sedimentary lipids and their compound-specific carbon isotope ratios were analyzed to evaluate characteristics and sources of organic matter. Results show that sedimentary As were well correlated with Fe and Mn oxides, suggesting that As exist as Fe/Mn oxide bound forms. Groundwater As far exceeded the drinking water guide value of 10 µg/L. Moreover, As concentrations in shallow groundwater were relatively higher. Lipids in clay were mainly originated from terrestrial higher plants, while that in fine sand samples were derived from terrestrial higher plants, microorganism and petroleum. Shallow fine sand samples were also characterized by evident in-situ biodegradation. Compound-specific carbon isotope compositions of sedimentary lipids showed that short-chain n-alkanes and n-alkanoic acids had more positive δ13C values compared to long-chain compounds, especially in shallow fine sand samples. δ13CTOC were also low in shallow fine sand samples. These results jointly indicate that these lipids in shallow fine sand samples acted as carbon source for indigenous microorganism and the short-chain components were particularly more vulnerable to biodegradation, which may contribute to high As concentrations in shallow groundwater. The new findings provide the first evidence that short chain length n-alkyl compounds afforded a source of potential electron donors for microbially mediated As mobilization process in the shallow aquifers.

Sulfur Cycling-Related Biogeochemical Processes of Arsenic Mobilization in the Western Hetao Basin, China: Evidence from Multiple Isotope Approaches.

The role of sulfur cycling in arsenic behavior under reducing conditions is not well-understood in previous investigations. This study provides observations of sulfur and oxygen isotope fractionation in sulfate and evaluation of sulfur cycling-related biogeochemical processes controlling dissolved arsenic groundwater concentrations using multiple isotope approaches. As a typical basin hosting high arsenic groundwater, the western Hetao basin was selected as the study area. Results showed that, along the groundwater flow paths, groundwater δ34SSO4, δ18OSO4, and δ13CDOC increased with increases in arsenic, dissolved iron, hydrogen sulfide and ammonium concentrations, while δ13CDIC decreased with decreasing Eh and sulfate/chloride. Bacterial sulfate reduction (BSR) was responsible for many of these observed changes. The δ34SSO4 indicated that dissolved sulfate was mainly sourced from oxidative weathering of sulfides in upgradient alluvial fans. The high oxygen-sulfur isotope fractionation ratio (0.60) may result from both slow sulfate reduction rates and bacterial disproportionation of sulfur intermediates (BDSI). Data indicate that both the sulfide produced by BSR and the overall BDSI reduce arsenic-bearing iron(III) oxyhydroxides, leading to the release of arsenic into groundwater. These results suggest that sulfur-related biogeochemical processes are important in mobilizing arsenic in aquifer systems.

Analytical methods and application of stable isotopes in dissolved organic carbon and inorganic carbon in groundwater.

RATIONALE: The stable isotopes of dissolved organic carbon (DOC) and inorganic carbon (DIC) provide insights into the carbon cycle, biogeochemical processes, and the fate of redox-sensitive elements in groundwater systems. The simultaneous determination of the stable isotope ratios (δ(13)C(DIC) and δ(13)C(DOC) values) in DIC and DOC in water samples would provide better understanding of those processes. METHODS: The conditions for pretreating water samples prior to determining their DIC and DOC stable isotope ratios were optimized with a series of experiments on pre-purging (GasBench needle versus blowing concentrator) and reaction conditions. The carbon stable isotope ratios were determined by isotope ratio mass spectrometry. Sequential determination of the δ(13)C(DIC) and δ(13)C(DOC) values was also carried out using the optimized conditions. National Institute of Standards and Technology (NIST) δ(13)C standards were utilized to verify the precision of the proposed method. RESULTS: The optimized pretreatment conditions for DIC isotope analysis involved pre-purging the empty sample bottle for 60 min using a pressurized helium gas-blowing concentrator and then reacting the sample with 85% H3PO4 for 60 min in a water bath at 60°C. The optimized pretreatment conditions for DOC isotope determination involved pre-purging the sample for 60 min with the pressurized helium gas-blowing concentrator after adding 0.1 mol L(-1) AgNO3 and 85% H3PO4 and then reacting with Na2S2O8 as an oxidant and AgNO3 as a catalyst, in a 100°C water bath for 60 min. CONCLUSIONS: With the optimized methods, the analytical precision of the δ(13)C(DIC) and δ(13)C(DOC) values of the reference samples was 0.02‰. The precision of δ(13)C(DIC) and δ(13)C(DOC) values in groundwater samples was 0.03‰ and 0.17‰, respectively. For the sequential determination of the DIC and DOC carbon isotope ratios, the precision of the δ(13)C(DIC) and δ(13)C(DOC) values in reference samples was better than 0.2‰.

Arsenic mobilization in aquifers of the southwest Songnen basin, P.R. China: evidences from chemical and isotopic characteristics.

High As groundwater has widely been found in the inland basins of China. Little is known about distribution and mobilization mechanisms of high As groundwater in the Songnen basin, where groundwater is the major source for drinking and irrigation. Eighty-seven groundwater samples, three surface water samples and sixty-three sediment samples were taken from the southwest of the Songnen basin, in order to investigate spatial distribution and constrains of groundwater As. Results showed that high As groundwater was generally of Na-Mg/Ca-HCO3 type, which had relatively low Eh values and neutral-weakly alkaline pH. High As groundwater was characterized by low concentrations of NO3(-) and SO4(2-), and high concentrations of Fe, Mn, and H2S. Around 65.5% of sampled shallow groundwater and 96% of sampled deep groundwater had As concentrations greater than 10 µg/L. Sediments had higher total As contents and higher Fe/Mn oxide-bound As contents in high As groundwater area than in the low As groundwater area. Distribution of groundwater As was dependent upon hydrogeologic settings, redox potential, microbial degradation of organic carbon, and precipitation of pyrite, siderite, and calcite. Along the groundwater flow path, As concentration showed an increasing trend. High As groundwater was mainly distributed in the low-lying areas. Reducing conditions were the major causes for As mobilization in the aquifers, which led to more As released from the sediments with higher contents of Fe/Mn oxide-bound As in higher As groundwater area. Results of (13)CDOC and (13)CDIC showed that dissimilatory Fe(III) reduction coupled with microbial degradation of dissolved organic carbon would be related to As mobilization in the aquifers. Although both Fe and As were released during these redox processes, pyrite, siderite and calcite precipitation would be the sink of dissolved As, which resulted in weak correlation between dissolved Fe and As.

Antagonistic effects of Lycium barbarum polysaccharides on the impaired reproductive system of male rats induced by local subchronic exposure to 60Co-γ irradiation.

Lycium barbarum, a famous Chinese medicinal herb, has a long history of use in traditional medicine as an antioxidant and to promote sexual fertility. Polysaccharides are the most important functional constituents in L. barbarum fruits. In this study, male rats were exposed to subchronic (60)Co-γ irradiation to investigate the effects of LBP on sperm quantity and motility, sexual ability, serum hormone levels, oxidative status and testicular tissue DNA damage on days 1, 7 and 14 of treatment. It was found that LBP significantly increased the sperm quantity and motility, shortened the erection, capture and ejaculation latencies, increased the number of captures and ejaculations, and improved the sexual ability of male rats. LBP also played a significant role in the recovery of serum testosterone levels, increased superoxide dismutase activity, decreased malondialdehyde levels, promoted oxidative balance and rescued testicular DNA damage. In conclusion, LBP has significant protective effects against damage induced by local subchronic exposure to (60)Co-γ irradiation, allowing rats to achieve near-complete recovery with LBP treatment.