Spring Area Research Articles

Analysis of the spatial and temporal evolution of drought in Henan based on a nonlinear composite drought index

It is of practical significance to provide a reference for drought mitigation and water resource enhancement planning in the Henan Province region and to analyze the spatial and temporal evolution characteristics of meteorological agricultural drought in the region. In this study, a multivariate (precipitation, potential evapotranspiration, soil moisture and normalized vegetation index) composite drought index CCDI was constructed based on the D Vine copula model, and the correlations between the CCDI and the standardized precipitation evapotranspiration index (SPEI) and between the CCDI and the standardized soil moisture index (SSI) were analyzed. The ability of the CCDI to evaluate meteorological agricultural drought was assessed, and typical drought events were selected for validation. The spatial and temporal evolution of drought in the Henan region from 1982 to 2022 was characterized using linear trends, M–K mutability tests, and drought centers of gravity, and future trends were analyzed using the Hurst index. The results show that (1) the CCDI correlates well with the SPEI and SSI (P < 0.01) and is able to characterize both meteorological and agricultural drought conditions in a better integrated way. (2) The fluctuation frequencies of the CCDI were obviously different at different time scales, indicating the different sensitivities of drought time scales to precipitation, potential evapotranspiration, soil moisture and the NDVI. All four seasons showed increasing trends at different rates. (3) During the study period of 1982–2022, the frequency of drought in Henan Province was mainly in the range of 21.95%-41.46%, and the intensity of drought occurrence was mainly dominated by light to moderate drought. (4) Based on the migration characteristics of the center of gravity of drought determined by ArcGIS, the center of gravity of drought during the study period is mostly concentrated in several cities in the central part of Henan, and the migration trajectory is mostly in the north‒south north–south direction, which is in line with the characteristics of the distribution of the data expressed by the standard deviation ellipse. (5) To analyze future drought trends in Henan, the mean values of the Hurst index in spring, summer, autumn and winter were 0.578, 0.766, 0.62 and 0.596, respectively, all of which showed persistent trends, while spring and winter Most areas may still have a dry trend in the future, the future dry trend in summer is mainly concentrated in the area around Henan, and the wet trend is distributed in the central-eastern part of the country and individual areas in the north and south. In the fall, most of the areas are wet trend, and individual areas have arid trend.The comprehensive drought index constructed in this paper can provide a new reference for drought prevention and drought relief in Henan Province.

Molecular Insights into the Reproductive Patterns and Genetic Structure of Wheat Stripe Rust in Ili, Xinjiang.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a globally significant fungal disease that seriously threatens wheat yield, particularly in China. This study investigates the genetic structure and reproductive patterns of Pst populations in Ili, Xinjiang, using 12 pairs of Simple Sequence Repeat (SSR) molecular markers. Analyses of 79 Pst isolates from either spring or winter wheat areas in Ili revealed three primary genetic clusters, indicating notable differences between populations associated with spring and winter wheat. The STRUCTURE results, complemented by UPGMA and PCoA analyses, highlight significant genetic diversity within these populations, with evidence of genetic recombination and sexual reproduction in certain areas. Pst populations in Ili exhibit a mixed mode of reproduction, predominantly sexual in Qapqal and Xinyuan D and primarily asexual within the spring wheat populations. The gene flow analysis underscores extensive inter-population communication, which facilitates the spread and adaptation of the pathogen across diverse wheat-growing environments. This study marks the first documentation of sexual reproduction in Pst within Xinjiang, providing new insights into its spread and genetic variation. These findings suggest that sexual reproduction may play a role in the regional adaptation and evolution of Pst, impacting future management strategies for wheat stripe rust in Xinjiang and potentially in broader Central Asian contexts.

УСЛОВИЯ ПЕРЕХОДА ОТ ДВУХСЛОЙНОЙ К ТРЕХСЛОЙНОЙ СТРАТИФИКАЦИИ ВОД В ЮГО-ЗАПАДНОЙ ЧАСТИ БАЛТИЙСКОГО МОРЯ НА ПРИМЕРЕ 2005 ГОДА

A study was conducted based on data from the MARNET automatic buoy station Arkona Becken, meteorological observations for 2005 and satellite data, with the aim of analysing the conditions of the transition from two-layer to three-layer stratification in the southwestern part of the Baltic Sea. As the southwestern part of the sea is the source region of the Cold Intermediate Layer (CIL) core waters, the thermohaline structure of the waters in this area in early spring is of particular importance for determining the properties of the CIL core waters throughout the year. The analysis of the thermohaline structure of the waters in this area in the early spring of 2005 revealed that during the period of maximum cooling of the surface waters, their characteristics exhibited a range of values for salinity (S) between 7.5 and 8.0 and for temperature (T) between 1.4 and 2.0 degrees Celsius. The transition from two-layer to three-layer water stratification lasted for 16 days (from 15 to 30 March) and was accompanied by prolonged easterly winds.

Ecohydrological role of groundwater outflows in the functioning of the ecotone zone in Lake Jaczno, Poland

The research determined the influence of natural groundwater outflows from the spring peat bog on the water supply and its quality in Lake Jaczno. Lake Jaczno is located in the Suwalski Landscape Park (SLP) in the Podlaskie Voivodeship, north-east Poland. The research was conducted from April 2009 to October 2010 and from September 2022 to September 2023. Water samples were collected from spring areas, shallow groundwater, and from Lake Jaczno. Fieldwork involved measuring flow, temperature, water electrolytic conductivity (EC), dissolved oxygen (DO) concentration, water oxygen saturation (WS), and water reaction (pH). Chemical analyses of water samples were carried out in the laboratory. Findings indicate that groundwater, spring water, and lake water in the SLP maintain high quality, with no significant changes in chemical composition over the past decades. Additionally, the physical water parameters display low temporal variability. The EC in the tested waters oscillates around 500 μS∙cm–1. Both spring and lake waters are well oxygenated (97–100%). Biogenic element concentrations exhibit higher variability, influenced by flora development in areas with natural groundwater outflows. High oxygenation of water contributes to increased concentrations of nitrates. The analysed waters exhibited similarity in the concentration and structure of phosphorus forms. Additionally, sediment chemical parameters at Lake Jaczno suggests a buffering capacity in the transitional zones between water and land. Despite similarities in chemical composition, sediment granulometry suggests low permeability, potentially restricting exchange between groundwater and surface waters. Monitoring springs in these environments is important due to their impact on quantity and quality of water in the analysed areas.

Woody flowering plants support early-spring pollinators in urban greenspaces

One threat pollinators face in a rapidly changing climate is the decoupling of their activity period from the blooming period of their host plants. Pollinators active in the earliest part of spring may be especially susceptible, as there are few alternative food resources available if they become active before their host plants begin blooming. Thus, urban landscapes, although often associated with decreased insect biodiversity, may buffer pollinators from such food shortages by offering a diversity of both native and exotic plant species that bloom in the late winter and early spring. However, more data are needed to ascertain the degree to which pollinators utilize flowers of spring-blooming exotic species. Here, we surveyed flower-visiting Hymenoptera and Diptera on 26 flowering plant taxa in three urban botanical gardens in the Oklahoma City metropolitan area in the early spring (March and April). We found that flowers of both native and exotic plants were attractive to Hymenoptera and Diptera, although pollinator visitation rates varied by more than an order of magnitude across plant taxa. Overall, woody plants were more attractive to pollinators compared to herbaceous plants, regardless of whether the plant was native or exotic. Implications for insect conservation: Our results suggest that regardless of native status, urban plants that bloom in the early spring—especially woody species—may be coopted to support pollinators that are especially susceptible to climate change. However, care needs to be taken to select plant species and varieties that pollinators will actually use.

Quantifying the influence of dominant factors on the long-term sandstorm weather - A case study in the Yellow River Basin during 2000–2021

Sandstorm is a disastrous weather phenomenon that often occurs in arid and semi-arid areas, endangering the ecological environment and affecting people's lives and property safety seriously. Since the 21st century, the sandstorm weather in the Yellow River Basin has ameliorated obviously. However, the causes of the long-term trends in sandstorms during 21st century were still unknown. In this study, fifteen influencing factors from five aspects: ecology, meteorology, hydrology, geography and man-made were selected to comprehensively analyze the driving mechanism of sandstorm activities in the Yellow River Basin since the 21st century, and the effect of each influencing factor on sandstorm weather was quantified. The results indicated that ecological, meteorological and geographical factors had dominant impacts on the spatio-temporal variation of sandstorms during 2000–2021, while hydrological and human factors played little role in the long-term variation of sandstorms. Sandstorms frequently occurred in semi-desert or grassland or non-high vegetation covered areas in spring. Vegetation coverage, precipitation, surface pressure, surface roughness, and soil moisture content were negatively correlated with sandstorms, while wind speed, friction velocity, evaporation, and soil temperature were positively correlated with sandstorms. Precipitation, runoff, evaporation, soil moisture content, soil temperature, and surface temperature indirectly acted on normalized brightness temperature dust index (NBTDI) and sandstorms by changing soil texture. Normalized Vegetation Index (NDVI) had direct negative effects on NBTDI, while wind speed 10 m (WS10m), slope of sub-gridscale orography (SOSGO), and forecast surface roughness (FSR) had direct positive effects on NBTDI. This study comprehensively revealed the dominant factors and their driving mechanism of sandstorm weather in the Yellow River Basin since the 21st century, which had practical application value for the prevention of sandstorms.

Method of experimental determination of the effective area of a pneumatic spring of high-speed rolling stock

Method of experimental determination of the effective area of a pneumatic spring of high-speed rolling stock

Prediction of Forest-Fire Occurrence in Eastern China Utilizing Deep Learning and Spatial Analysis

Forest fires are a major natural calamity that inflict substantial harm on forest resources and the socio-economic landscape. The eastern region of China is particularly susceptible to frequent forest fires, characterized by high population density and vibrant economic activities. Precise forecasting in this area is essential for devising effective prevention strategies. This research utilizes a blend of kernel density analysis, autocorrelation analysis, and the standard deviation ellipse method, augmented by geographic information systems (GISs) and deep-learning techniques, to develop an accurate prediction system for forest-fire occurrences. The deep-learning model incorporates data on meteorological conditions, topography, vegetation, infrastructure, and socio-cultural factors to produce monthly forecasts and assessments. This approach enables the identification of spatial patterns and temporal trends in fire occurrences, enhancing both the precision and breadth of the predictions. The results show that global and local autocorrelation analyses reveal high-incidence areas mainly concentrated in Guangdong, Fujian, and Zhejiang provinces, with cities like Jiangmen exhibiting distinct concentration characteristics and a varied spatial distribution of fire occurrences. Kernel density analysis further pinpoints high-density fire zones primarily in Meizhou, Qingyuan, and Jiangmen in Guangdong Province, and Dongfang City in Hainan Province. Standard deviation ellipse and centroid shift analysis indicate a significant northward shift in the fire-occurrence centroid over the past 20 years, with an expanding spatial distribution range, decreasing flattening, and relatively stable fire-occurrence direction. The model performs effectively on the validation set, achieving an accuracy of 80.6%, an F1 score of 81.6%, and an AUC of 88.2%, demonstrating its practical applicability. Moreover, monthly fire zoning analysis reveals that high-incidence areas in spring and winter are mainly concentrated in Guangdong, Fujian, Zhejiang, and Hainan, while autumn shows widespread medium-incidence areas, and summer presents lower fire occurrences in most regions. These findings illustrate the influence of seasonal climate variations on fire occurrences and highlight the necessity for enhanced fire monitoring and prevention measures tailored to different seasons.

Hydrochemical Characteristics and Variation in Karst Groundwater in the Baiquan Spring Area of Xingtai Over the Last 30 Years

To elucidate the variation patterns in the hydrochemical characteristics of karst groundwater in the Baiquan Spring area of Xingtai over the past 30 years, an integrated approach utilizing mathematical statistics, Piper trilinear diagrams, Gibbs diagrams, and ion ratio analyses was employed. Comparative analysis was conducted on 62 sets of karst water samples collected during the dry seasons of 1991 and 2020. The findings indicated that the groundwater in the spring area was generally weakly alkaline with a low salinization degree, predominantly characterized by Ca2+ and HCO3- as the dominant ions. Compared to that in 1991, the alkalinity of groundwater in 2020 had intensified, with a general increase in the concentration of various indicators. The hydrochemical types had shifted from the relatively concentrated HCO3-Ca and HCO3-Ca·Mg types to a broader spectrum of types, gradually exhibiting a salinization trend. The distribution characteristics of exceeding components such as TDS, Na++K+, SO42-, and F- showed significant spatial differences. Rock weathering played a pivotal role in the changes observed in the hydrochemical components of groundwater, with enhanced cation exchange and evaporation processes further influencing the hydrochemical characteristics and their spatial distribution.

Applicability of Na/K geothermometer to the metapelitic non-volcanic geothermal fields in the Taiwan orogenic belt

Taiwan is situated at one of the world's most active orogenic belts with arc-continent collision. This event resulted in the burial and uplift of mudstones along the continental margin, transforming them into metapelitic mountains. These mountains intercept rainfall and serve as the driving force for deep water circulation, enabling meteoric fluids to carry residual heat to the surface, thus giving rise to hot springs. The Taiwan orogenic belt is home to over 100 hot springs, and some of the hot spring reservoir temperatures such as Chingshui, Tuchang-Jentse, Lushan, Chihpon, and Chinlun exceeds 160 °C. Geothermal development in Taiwan has been carried out in such hot spring areas without any volcanic activities.In order to assess reservoir temperatures and confirm the applicability of the Na/K geothermometer to such high temperature hot spring system, the concentrations of Na+, K+, and SiO2 were analyzed from geothermal wells. Considering the mineral composition of metapelitic host rock, a new Na/K geothermometer is proposed based on equilibrium between albite and illite:T>180∘C,T(∘C)=2474log(NaK)+3.73−273.15This formula is only applicable in a reducing fluid and does not involve the formation of clay minerals except illite. It also requires several years to reach equilibrium. When using this formula to estimate reservoir temperatures, careful consideration of various conditions is necessary. It is advisable to incorporate both quartz geothermometer and down-hole temperature measurements for a more accurate assessment. Combining the Na/K geothermometer with the quartz geothermometer, along with other geochemical data such as Cl−concentrations and δD and δ18O of fluid, helps to understand whether hydrothermal fluids have undergone evaporation, dilution, and/or mixing processes.

Analysis on Spatial Variability of Hydrochemical Characteristics and Control Factors of Jinan Baotu Spring Area

To understand the karst groundwater hydrochemical characteristics and ion sources of the Jinan Baotu Spring area, this study focused on the three functional zones as an indirect recharge area, direct recharge area, and discharge area. Through water sample collection and testing, the spatial variability of groundwater chemical characteristics in different functional zones and the formation mechanism were analyzed using hydrochemistry parameter statistics, multivariate statistics, self-organizing map, hydrochemistry graphical analysis, ion ratios, and other methods, guided by the theory of groundwater flow system and combined with regional physical geography and hydrogeological conditions. The results showed that： the groundwater of each functional zone was alkaline as is typical in the dissolution of carbonate minerals. Owing to the different groundwater runoff pathways, the variability of water chemistry parameters in different functional areas was obvious. The groundwater of the discharge area was recharged by both the direct recharge area and the indirect recharge area. The hydrochemistry type changed from HCO3-Ca type to HCO3·SO4-Ca type through the indirect recharge area to the discharge area. The presence of a small amount of gypsum dissolution within the aquifer generated Ca2+ and SO42-. The ions in groundwater mainly came from the dissolution and filtration of aquifer rock minerals, and at the same time, they were affected by cation exchange, mineral dissolution equilibrium, and the combined effects of human activities. The groundwater in the Baotu Spring area was greatly influenced by human activities, which to some extent affected the evolution of groundwater hydrochemistry in the spring area.

Seismic Performance of Precast Concrete Exterior Beam-Column Joint with Disc Spring Devices

ABSTRACT To improve the seismic performance of precast concrete reinforced frame structures which are widely used worldwide, and enable a certain repairable function for the precast structure after an earthquake, this paper proposes a new type of precast concrete frame joint using a full grouting sleeve connection with a disc spring device. The disc spring device was connected in series to the longitudinal reinforcement located in the plastic hinge zone at the beam end to provide a restoring force and protect the concrete. Six exterior beam-column joints consisting of one cast-in-situ beam-column joint and five precast concrete frame joints, using a fully grouted sleeve connection equipped with or without a disc spring device, were designed and fabricated. The failure process, hysteretic characteristics, and energy dissipation capacity of the joint specimens were analyzed based on reversed cyclic loading test. The results showed that the energy dissipation and seismic performance of the newly precast concrete joints equipped with the disc spring device were better than those of the precast concrete frame joints connected by ordinary grouting sleeves without a disc spring device. The disc spring device proposed in this study plays a similar role as a damper in the precast joint during loading and has the characteristics of concentrated damage as it transfers part of the damage in the joint core area to the built-in disc spring area at the beam end. Additionally, the deformation of the precast joints under a lateral seismic load was theoretically calculated, the calculated results were in good agreement with the experimental results.

Aeromagnetic Data Analysis of Geothermal Energy Potential of a Hot Spring Area in Western Saudi Arabia

Aeromagnetic Data Analysis of Geothermal Energy Potential of a Hot Spring Area in Western Saudi Arabia

Thermal profiles of Cicindelidia haemorrhagica (Coleoptera: Cicindelidae) activity in hot springs in Yellowstone National Park.

The wetsalts tiger beetle, Cicindelidia haemorrhagica (LeConte) (Coleoptera: Cicindelidae), is found in several active thermal hot spring areas in Yellowstone National Park (YNP) where substrate surface temperatures can exceed 50 °C. However, relationships between surface temperatures and the time adults spend on them remain poorly understood. Therefore, we characterized thermal profiles of Dragon Spring and Rabbit Creek, 2 thermally active research sites containing C. haemorrhagica in YNP, to quantify the time adults spend at different surface temperatures. We took 58 thermal video recordings of adults over 6 total days of observation ranging from 10 to 15 min for each adult. Thermal video analysis results indicated a positive relationship between the total time adult beetles spent on surface temperatures from Dragon Spring and Rabbit Creek as temperatures increased from 20 °C. Once surface temperatures exceeded 40 °C, the total time spent at those surface temperatures declined. Adults were recorded on substrates exceeding 50 °C at one of the 2 research locations. Rabbit Creek had substantially more instances of adults present with surface temperatures exceeding 40 °C, including one individual on a surface temperature of 61.5 °C. There were 3 instances of beetles spending more than 4 min at a particular surface temperature, all within the preferred range of 30-40 °C. Our thermal profile results and previous behavioral observations suggest that adults may be resistant to the heat produced from the thermal waters that influence the substrate temperatures but may not be subject to high surface temperatures as previously reported.

Prescribed fire increases forage mineral content in grazed rangeland

Background Sustainable rangeland management balances production and conservation. While a broad literature describesthe conservation benefits of prescribed fire, benefits for livestock production have emerged more slowly. Mineral nutrition is important for livestock health and performance, but the impact of prescribed fire on mineral concentration of forages, especially in the northern US Great Plains, remains unknown. Aims We investigated how burning affects the mineral concentration of forage early and late in the growing season. Methods Data were collected on mixed-grass prairie in south-central North Dakota, USA. Vegetation was clipped from recently burned, 1 year post-fire, 2 years post-fire, and not-yet-burned patches at the same sampling points in spring and late summer. Samples were analysed for calcium, phosphorus, magnesium, potassium, copper, iron, manganese, and zinc concentration. Key results Burning increased forage mineral concentration across most minerals. Phosphorous, potassium, copper and zinc were higher in burned areas in late spring and summer; calcium, magnesium and manganese were only higher during the late summer; Late-season iron levels increased with time since fire. Conclusions Prescribed fire has a positive effect on forage mineral content. Implications Prescribed fire has the potential to reduce mineral supplementation costs and improve cow performance.

Environmental quality of the Paraim River springs, far south of Piauí

The small flows of runoff give rise to water bodies which, through their multiple uses, contribute to satisfying the basic vital needs of animals, plants and ecosystems. Spring areas play an important role in maintaining the environmental quality of the basin. To this end, it is essential that these areas have an effective conservation policy. The aim of this study was to determine the environmental quality of the Paraim River's spring areas, emphasizing the physical-chemical and biological quality of the water and characterizing local environmental conditions through macroscopic assessment. Visits were made to seven of the Paraim River's perennial springs and the macroscopic assessment made it possible to identify the impacts observed in the springs and permanent preservation areas, access conditions, proximity to rural centers and types of use of the springs. The physical-chemical and microbiological parameters of the water were assessed and compared with Resolution 357/2005 of the National Environment Council (CONAMA) and the Water Quality Index (IQA). The macroscopic assessment of the springs showed that 57.1% of the springs were rated as "excellent" or "good" and only one spring was rated as "very bad". Determining the WQI of the springs resulted in values varying between 59 and 86 in the dry season and between 56 and 89 in the rainy season. This shows that all the springs evaluated had satisfactory WQIs ("good" or "excellent"). The assessment of water quality made it possible to observe the relationship between the quality parameters, as well as their influence on the macroscopic characteristics of the springs. In this way, the information obtained indicates that, despite the good quality of the water, the assessment of the environmental situation of the springs warns of the need for future strategies aimed at planning for land use and environmental management of micro-watersheds.

Tracing Hydrological Processes: Insights from Hydrochemical and Isotopic Investigations in the Northern Part of Croatian Dinaric Karst

This study presents the findings derived from a three-year monitoring programme focusing on the hydrochemical composition and stable isotope signatures (δ18O, δ2H) within the vulnerable karst groundwater system in Croatia's northern Dinaric karst region. Covering an area of 1980 km2 across Kapela Mountain and its foothills, this groundwater system falls within the Kupa River basin and encompasses the catchment areas of the main springs across two spring levels of the Dobra, Mrežnica, and Slunjčica Rivers (namely the Vitunj, Zagorska Mrežnica, Dretulja, Veliko Vrelo, Gojak, Tounjčica, Mrežnica, and Slunjčica springs). Given the complex hydrogeological framework, prior studies have not extensively addressed the hydrochemical characteristics of this region, thereby necessitating a comprehensive investigation to elucidate system dynamics. This paper outlines the first investigation employing stable isotopic analyses within the karst groundwater system of Kapela Mt. The main results and conclusions of the research include: (i) the aquifers across Kapela Mt. drain mainly limestones, (ii) water–rock interaction and carbonate weathering are significant contributors to water geochemistry, (iii) there is a slight human impact on the Gojak and Tounjčica spring waters, (iv) the mean residence time of water in the observed aquifer is up to 1.5 years, (v) the new LMWL was calculated for Kapela Mt. based on a three-year dataset (June 2018 – May 2021), (vi) in the north Dinaric karst, the predominant origin of precipitation is from the Mediterranean air mass, (vii) Velebit Mt. has a strong influence on the precipitation isotopic composition of the study area.

Spatio-temporal dynamics of the carbonate system during macroalgae farming season in a semi-closed bay in southeast China

Ocean Negative Carbon Emission (ONCE) involves utilizing natural marine chemistry and biology, along with mariculture, to achieve carbon sink goals. Growing awareness of the interplay between aquaculture and the coastal carbonate system has drawn researchers’ attention amid ring CO2 concentrations and the negative impacts of aquaculture on the environment. In this study, twelve sites representing different maricultural types were selected, including macroalgae, shellfish, fish, and non-farming areas. The environmental factors, dissolved inorganic carbon (DIC), total alkalinity (TA), and pCO2, were measured monthly during kelp farming periods. Nitrate is a major component of total nitrogen, and the NO3-N concentration in the macroalgal culture zone was lower than others, indicating effective nitrogen removal by macroalgae aquaculture. TA and DIC in non-farmed areas demonstrated larger variation ranges than in farming areas, probably due to the effects of precipitation on salinity. Aquaculture activities effectively maintained TA and DIC, with macroalgae cultivation playing an important role in TA stability, potentially resisting acidification. The pCO2sea-air of macroalgae culture areas in spring was slightly negative, suggesting carbon sink potential. However, further research is needed to assess the full extent of this “fourth type” of blue carbon, including accurate carbon footprint calculation and the contributions of particulate organic carbon and recalcitrant dissolved organic carbon. This study provided insight into the comprehensive contribution of different aquaculture types to the fishery environment and carbonate system, which can help guide aquaculture management and facilitate the carbon-neutral transition of aquaculture.

Hydrochemical evolution of groundwater in a river corridor: the compounded impacts of various environmental factors

Various environmental factors could induce groundwater hydrochemical evolution, which should be considered when addressing groundwater environmental issues. However, the complex interactions among the environmental controls remain unknown for a groundwater flow system spanning multiple geological units. To fill this gap, we conducted a study on the groundwater hydrochemical evolution in the fluvial corridor of the Fen River, Northern China, utilizing a combination of hydrogeochemical and multiple isotope methods. Results reveal that the groundwater in the corridor has significantly degraded due to high concentrations of SO42-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{SO}}_{4}^{2 - }$$\\end{document}, NO3-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NO}}_{3}^{ - }$$\\end{document}, Cl−, or F−. We find an unordered evolution of the hydrochemical composition of groundwater along this corridor. These evolutions are driven by mineral dissolution/precipitation, dedolomitization, and cation exchange processes. Human activities play a significant role, with notable contributions including NO3-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NO}}_{3}^{ - }$$\\end{document} fluxes from agricultural fertilizers, manure, and sewage, as well as SO42-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{SO}}_{4}^{2 - }$$\\end{document} fluxes arising from coal mining activities. The combination between karst spring areas and faults/uplifts, between coal-bearing strata and mining activities fosters the mixing of karst water/mine water with shallow groundwater, promoting dramatic hydrochemical evolution of groundwater. The flat terrain and the natural blockage formed by mountains significantly enhance water–rock interactions and groundwater evaporation by slowing groundwater flow. The contribution of evaporation on groundwater salinity ranges from ~ 0.2% to 4.8%, highlighting its importance in the groundwater hydrochemical evolution. This study unravels the multifaceted nature of groundwater hydrochemical evolution. It emphasizes the four types of environmental controls, including hydrogeochemical processes, climate factors, human activities, and variations in geological settings, can be equally important, which is usually ignored. The findings enrich our understanding of groundwater evolution and highlight the challenges encountered in regions composed of diverse geological units.

Impact of drought on Oncomelania hupensis snails breeding in the Poyang Lake area

To examine the impact of arid climates on distribution of Oncomelania hupensis snails in the Poyang Lake area, so as to provide insights into precision control of O. hupensis snails in the Poyang Lake area. O. hupensis snails-infested grass islands in Hukou County, Lianxi District and Lushan City in the northern Poyang Lake area, and Jinxian County, Nanchang County and Poyang County in the southern Poyang Lake area were selected as the study areas, and the occurrence of frames with living snails and the mean density of living snails were captured from snail surveys in the study areas in spring and autumn each year from 2006 to 2023. Five years 2007, 2011, 2013, 2019 and 2022 were selected as drought years, and the mean daily water levels were collected at the Xingzi hydrological station in the drought years, normal flow year (2012) and flood year (2020). The numbers of days with water levels ranging from the lower elevation (11 m) to the upper elevation (16 m) for snail survival and the numbers of days with water levels of 11 m and below were collected in the Poyang Lake area, and the changes of snail indicators were compared in different grass islands in the Poyang Lake area before and after drought. The numbers of days with water levels ranging from 11 to 16 m were 110, 88, 136 d and 125 d at the Xingzi hydrological station in four drought years 2007, 2011, 2013 and 2019, which were less than in the flow year and flood year, and the days with water levels of 11 m and below were 242, 277, 220 d and 198 d in four drought years 2007, 2011, 2013 and 2019, which were longer than in the flow year and flood year. A total of 416 snails-infested marshlands were surveyed in the Poyang Lake area from 2006 to 2021, and the survey marshlands accounted for 43.12% (307/712) and 46.98% (109/232) of total marshlands in the southern and northern Poyang Lake areas, respectively. The median occurrence of frames with living snails and mean density of living snails were 0.60% (interquartile range, 4.04%) and 0.010 1 snail/0.1 m2 (interquartile range, 0.076 1 snail/0.1 m2) in drought years, which were both lower than those [1.33% (5.19%) and 0.022 8 (0.098 9) snail/0.1 m2] in non-drought years (χ2= 42.170 and 44.911, both P values < 0.01). The proportion of grass islands with a continuous decline in snail indicators was higher in the southern Poyang Lake area than in the northern Poyang Lake area after the next year of drought (24.24% vs. 2.33%; χ2 = 10.633, P < 0.01), and the proportion of grass islands with rebounding snail indicators was higher in the northern Poyang Lake area than in the southern Poyang Lake area (53.49% vs. 15.76%; χ2 = 26.966, P < 0.01). A longitudinal analysis of snail indicators in marshlands with rebounding snail indicators after drought showed 1 to 5 years for return to pre-drought snail status, with a median of 2 (interquartile range, 1) years, and snail status was more likely to rebound if the occurrence of frames with living snails and the mean density of living snails were 2.11% and 0.025 5 snail/0.1 m2 and greater in snails-infested grass islands. Drought causes a remarkable decline in O. hupensis snail indicators in the Poyang Lake area, with a more remarkable impact in the southern Poyang Lake area, and 1 to 5 years are required for return to pre-drought snail status.