Major Concentrations Research Articles

Hydrochemical and isotopic composition of periglacial watersheds in Northern Patagonian Andes

Mountain periglacial environments are important sites of water storage and distribution to downstream areas. The present study was conducted in the “La Hoya” subwatershed, in the Northern Patagonian Andes. La Hoya is the main water recharge area of the “Los Bandidos” watershed, from which fresh water is used for human consumption. The aim of this work was to study the hydrogeochemical and isotopic composition of this watershed and evaluate the hydrological and ionic contributions from periglacial landforms, accounting for annual water flow hydrodynamics and climatic trends. Meteorological data, spring and stream flows, electrical conductivity, isotopic content, and major ion concentrations of snow, spring, and stream samples were analyzed from December 2020 to November 2021. Snow melting is the main water contribution to the mountain watershed. Part of the snowmelt drains superficially during the melting season and part of it infiltrates into periglacial landforms, where it is provisionally stored as groundwater. Chemical weathering during groundwater-rock interaction is the main process that regulates water chemical composition, dominating the dissolution of CO2(g) and carbonates, which controls the waters to be of the Ca–HCO3 to Ca–Mg–HCO3 facies type of groundwater. The climate tendency for the last sixty years in this area reflects a decrease in precipitation and an increase in temperatures. This climate trend could affect periglacial environments, modifying the chemical and physical processes that take place in them, which could affect the chemical water quality and the hydrological behavior of the watershed. The chemical and hydrological behavior in watersheds for human consumption should be specially monitored for better use of this resource.

Origin and evolution of intercrystalline brine in the northern Qaidam Basin based on hydrochemistry and stable isotopes

The Kunteyi Basin, located in northern Qaidam, is known as a significant potash ore deposit in China. It is of great significance to study the origin of the potassium-rich intercrystalline brine to support the exploitation of potassium salts. In this study, the major ion concentrations and isotopic ratios (δ2H, δ18O, and δ11B) of intercrystalline brine were used to analyze the evolution of the brine. The results show that the intercrystalline brine has a much higher concentration of total dissolved solids compared with the oil-field brine. Most of the ions are enriched except Ca2+ and Br−. The value of δ2H and δ18O are much negative while the δ11B values are positive. The analysis of CNa/CCl, CBr/CCl, Cl/(Na + K + Mg) and isotopes ratios, indicate that (1) Atmospheric precipitation is the primary source of water in brine; (2) The salinity of the brine is mainly influenced by halite dissolution; (3) The study area was influenced by the deep hydrothermal fluids. The thermal water recharged the Pleistocene layer, reacted with polyhalite, and formed Mg- and K-rich brine. The solution rose along the channel formed by the Shuangqiquan Fault and was supplied to the shallow intercrystalline brine.

Hydrogeochemical characteristics and genesis of Hongshuilantang Hot Spring and its water temperature anomalies during the Rushan earthquake swarm in Eastern China

Water temperatures of hot springs close to tectonic fault zones often show some variations before earthquakes, and analyses of earthquake precursors in hot springs have significant referential meaning for earthquake monitoring and forecasting. This study measured the concentration of major ions in water from the Hongshuilantang Hot Spring in 2017 and 2020. The ion composition was classified by hydrochemistry into the HCO3·SO4-Na chemical type. The composition of hydrogen and oxygen isotopes in the Hongshuilantang Hot Spring were located near the global meteoric water line (GMWL), indicating that the recharge source of the hot spring was meteoric water. The δD and δ18O values were not plotted on the Glogal Meteroric Water Line (GMWL), and there were some deviations, which suggested that hot spring water underwent water–rock interactions. Deep circulation water played an important role during the evolution process of thermal water. Water temperature showed a decreasing trend from October 2013 to June 2015 during the Rushan earthquake swarm in eastern China. Because of the occurrence of the earthquake swarm, we inferred that regional stress in this area began to be released, allowing continuous rebalancing. Free surface water appeared in some aquifers, and the seepage of low-temperature underground water into the upper aquifer led to a drop in water temperature in the hot spring. The Hongshuilantang Hot Spring and the epicenter of the Rushan earthquake swarm were located on the Muping–Jimo seismological fault zone, with the same seismotectonic system and some genesis relationships.

Hydrochemical and stable isotopes (δ2H and δ18O) changes of groundwater from a spring induced by local earthquakes, Northwest China

It has been well reported that earthquakes can cause changes in groundwater chemistry and isotopes, and much of those changes were occurred in wells or hot springs; however, changes in cold spring caused by local small earthquakes have received less attention. Here, we collected continuous monitoring of the X10 spring (September 2018 to December 2019), investigated the hydrogeochemical characteristics of the spring by using water chemistry analysis and isotope methods. We compared the changes in water chemical ion concentrations and hydrogen-oxygen isotope ratios with the surrounding seismic activity, and the results show that 1) major chemical ion concentrations in X10 springs have an annual dynamic pattern of being high in winter and low in summer, and this change may be related to the seasonal effect of snowmelt; 2) the spring water originates from long-distant meteoric water, snowmelt, and bedrock fissure water and is affected by rock weathering and evaporation; 3) the hydrogen and oxygen stable isotope ratios and HCO3− concentration in groundwater are sensitive to local small seismic activity. We considered that small earthquakes can change the permeability in fault zones or aquifers, leading to mixing of groundwater with different chemical composition and isotopes. Our study demonstrates that the hydrogen and oxygen stable isotopes are more sensitive to seismic activity than the commonly used chemical constitutents, and that the sensitive constitutents vary in different observation wells or springs; therefore, combined monitoring of isotopes and water chemistry should be considered in the future to capture hydrogeochemical precursor signals caused by earthquakes.

Trend Analysis of Precipitation, Runoff and Major Ions for the Russian Part of the Selenga River Basin

At present, the problem of climate change is becoming increasingly acute. This is especially pressing for Lake Baikal, a World Natural Heritage site. The Russian part of the Selenga watershed is a suitable site for climate change research. The study of changes in precipitation, runoff, and chemical runoff is important for sustainable water resources management. This study presents a trend analysis of precipitation and runoff at hydrological stations and weather stations in the Russian part of the Selenga River basin. A comparative analysis of the concentrations of major ions in the surface water of the Selenga River depending on water levels was also carried out. Analysis of the data series on precipitation revealed a slight negative trend at the Novoselenginsk, Ulan-Ude, and Kabansk stations, and a weak positive trend—at the Kyakhta station. Runoff analysis revealed negative trends at the two used stations (Novoselenginsk and Mostovoi). The hydrochemical regime of the Selenga River is characterized by an increase in major ions and salinity during winter low-water periods, and a decrease during high-water periods. Mineralization and major ion content are lower in the high-water period (2019–2021) than in the low-water period (2015–2017).

Dynamics of surface water and groundwater quality using water quality indices and GIS in river Tamsa (Tons), Jalalpur, India

Water samples were collected along the Tamsa river and adjacent groundwater in 2019 and 2020, and analyzed for pHh, temperature, TDS, EC, TH, major ions, and trace elements. Statistical and spatial analysis and geochemical plotting were used. Results show that both river water and groundwater are hard and slightly alkaline. Groundwater has higher concentrations of major ions and silica than river water. River water is more alkaline than groundwater. The main hydrogeochemical facies is the Ca + Mg-HCO3 type. Mg + 2, HCO3, Ni, WAWQI, TH, and MH exceed the permissible limits in both river and groundwater at a few locations, and TDS, Ca + 2, Cl-, F-, Mg/Ca, RSC, KR, PS, CR also exceed in groundwater at few locations. Water is suitable for most locations for drinking, domestic, and irrigation purposes. Rock weathering dominance, cation-anion exchange, and anthropogenic activities are found to influence water chemistry in the region.

Structural supercapacitor electrolytes based on cementitious composites containing recycled steel slag and waste glass powders

Incorporating solid wastes into cement-based materials is beneficial for the waste disposal and the conservation of natural resources. In this study, cement-based electrolyte incorporated with recycled steel slag powder (SSP) and waste glass powder (GP) was proposed as a potential candidate for assembling structural supercapacitor cells (SSCs) with multi-functionality. Compared with pure cement devices, the 28-day conductivity and areal capacitance of the SSCs containing SSP and GP increased by up to 112% and 84%, respectively, at a current density of 0.1 mA cm−2. On the one hand, the addition of SSP and GP increased the pore volume in the cement-based electrolyte, which in turn resulted in more paths for ion transport. On the other hand, the presence of SSP and GP increased the concentration of major ions, such as Na+ and OH−, in pore solution. Both the increased ion transport paths and the improved ion concentration contributed substantially to the enhancement of the energy storage performances of the SSCs. At 28 days, an additional incorporation of 10% GP made up for the strength loss caused by SSP as an appropriate amount of GP with high pozzolanic activity resulted in an increased amount of C-S-H product, a reduction of porosity, and a denser microstructure. The proposed SSCs containing the cement-based electrolyte with cement partially replaced by 20% SSP and 10% GP is competitive for the development of green building energy storage devices.

Assessment of Surface Water Quality Using the Water Quality Index (IWQ), Multivariate Statistical Analysis (MSA) and Geographic Information System (GIS) in Oued Laou Mediterranean Watershed, Morocco

Surface water is used for a variety of purposes, including agriculture, drinking water, and other services. Therefore, its quality is crucial for irrigation, human welfare, and health. Thus, the main objective is to improve surface water quality assessment and geochemical analysis to evaluate anthropogenic activities’ impact on surface water quality in the Oued Laou watershed, Northern Morocco. Thirteen surface water samples were characterized for 26 physicochemical and biological parameters. In this aspect, emerging techniques such as multivariate statistical approaches (MSA), water quality indices (WQI), irrigation water quality (IWQI), and Geographic Information System (GIS) were employed to identify the sources of surface water pollution, their suitability for consumption, and the distribution of surface water quality. The results showed that the major ion concentrations were reported in the following order: Ca2+, Na+, Mg2+, and K+; and HCO3− > CO32− > Cl− > SO42− > NO3− > F− > PO43− > NO2−. It was also demonstrated that almost all parameters had concentrations lower than World Health Organization (WHO) limits, except for bicarbonate ions (HCO3−) and the biochemical oxygen demand for five days (BOD5), which exceeded the WHO limits at 120 mg/L and 3 mg/L, respectively. Furthermore, the types of Ca2+-HCO3− (Calcium-Bicarbonate) and Ca2+-Mg2+-HCO3− (Calcium-Magnesium-Bicarbonate) predominated in surface water. The Principal Component Analysis (PCA) indicates that the Oued Laou river was exposed to two forms of contamination, the first being attributed to anthropogenic activities such as agriculture, while the second reflects the water-sediment interaction. The Hierarchical Cluster Analysis (HCA), reflecting the mineralization in the study area, has classified the samples into four clusters. The Inverse Distance Weighting (IDW) of the WQI indicates that 7.69% and 38.46% of the surface water represent, respectively, excellent and good quality for drinking. At the same time, the IWQI revealed that 92.30% of the water surface is good for irrigation. As a result, the combination of WQIs, PCA, IWQI, and GIS techniques is effective in providing clear information for assessing the suitability of surface water for drinking and its controlling factors and can also support decision-making in susceptible locations such as the Oued Laou river in northern Morocco.

Integrated Assessment of Chemical and Biological Recovery After Diversion and Treatment of Acid Mine Drainage in a Rocky Mountain Stream.

Responses of stream ecosystems to gradual reductions in metal loading following remediation or restoration activities have been well documented in the literature. However, much less is known about how these systems respond to the immediate or more rapid elimination of metal inputs. Construction of a water treatment plant on the North Fork of Clear Creek (NFCC; CO, USA), a US Environmental Protection Agency Superfund site, captured, diverted, and treated the two major point-source inputs of acid mine drainage (AMD) and provided an opportunity to investigate immediate improvements in water quality. We conducted a 9-year study that included intensive within- and among-year monitoring of receiving-stream chemistry and benthic communities before and after construction of the treatment plant. Results showed a 64%-86% decrease in metal concentrations within months at the most contaminated sites. Benthic communities responded with increased abundance and diversity, but downstream stations remained impaired relative to reference conditions, with significantly lower taxonomic richness represented by a few dominant taxa (i.e., Baetis sp., Hydropsyche sp., Simulium sp., Orthocladiinae). Elevated metal concentrations from apparent residual sources, and relatively high conductivity from contributing major ions not removed during the treatment process, are likely limiting downstream recovery. Our study demonstrates that direct AMD treatment can rapidly improve water quality and benefit aquatic life, but effectiveness is limited, in part, to the extent that inputs of metals are captured and treated. Consideration should also be given to the effects of elevated major ion concentrations from the treated effluent not removed during the lime treatment process. Continued chemical and biological monitoring will be needed to quantify the NFCC recovery trajectory and to inform future remediation strategies. Environ Toxicol Chem 2023;42:512-524. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Groundwater Quality and Potential Pollution in the Southern Shimabara Peninsula, Japan

Nitrate pollution in groundwater is a severe problem in Shimabara Peninsula, Nagasaki Prefecture, Japan. Previous studies have investigated water quality characteristics in the northern part of the peninsula and shown serious effects of nitrate pollution in the groundwater. The present study aimed to investigate the groundwater quality in the southern areas of the peninsula for improved understanding of the water quality status for the entire peninsula. Groundwater samples were collected at 56 locations in Minami-Shimabara City from 28 July to 4 August 2021. The spatial distribution of water quality constituents was assessed by Piper-trilinear and Stiff diagrams for major ion concentrations. One agricultural area in the western parts exceeded Japanese recommended standards for water. According to the Piper-trilinear diagram, 44 sampling sites (78.6%) were classified as alkaline earth carbonate type, nine sites (16.1%) as alkaline earth non-carbonate type, and three sites (5.3%) as alkaline carbonate type. Stiff diagrams displayed Ca-HCO3 water type for most of the sites. Na-HCO3 and Mg-HCO3 types were found in coastal areas. Principal component analyses showed that the first component corresponded to dissolved constituents in groundwater and denitrification, the second effects of ion exchange and low nitrate pollution, and the third effects of severe nitrate pollution. Hierarchical cluster analysis was used to classify the groundwater into five groups. The first group included sites with relatively high nitrate concentration. The second group had relatively low ion concentration, distributed from center to eastern parts. The third group included intermediate ion concentration, distributed at lower altitudes along the coastal line. The fourth and fifth groups had a higher ion concentration, especially characterized by high sodium and bicarbonate concentration.

Precipitation chemistry in the westerly domain of the Tibetan Plateau

Based on the interaction of water with natural and anthropogenic airborne particles, precipitation chemistry reflects the degree of pollution in the area. Characterizing the local hydrochemical features and regional geochemical cycle requires an understanding of the chemical characteristics of precipitation and its sources. As a result, major ion concentrations were quantified and their chemical properties were identified in event-based precipitation samples. Ca2+, Mg2+, and K+ were crucial in neutralizing the acidity of precipitation. The order of the ions' concentrations was Na+ > SO42− > HCO3− > Ca2+ > Cl− > Mg2+ > K+ > NO3−. Ionic sources in the region included biomass burning, anthropogenic emissions, crustal dust, and salt. The HYSPLIT trajectory further supports biomass burning and aerosol movement from multiple sites. The National Center for Environmental Prediction Final dataset, clusters of air mass backward trajectory analysis, and source identification suggest that the higher concentration of anthropogenic ions (SO42−) in the study site may have been transported from Xinjiang and nearby locations in Central Asia and the Middle East. These datasets provided an overview for evaluating the regional atmospheric chemistry over the westerly domain of the Tibetan Plateau during the monsoon season based on the ionic characteristics.

Integrated Hydrogeochemical Groundwater Flow Path Modelling in an Arid Environment

In this study, water-rock interaction, salinity sources, evolution, and the mixing of groundwater were modelled. The objectives of this research are to understand the hydrogeochemical factors that govern groundwater composition in a shallow aquifer system, Jazan Province, Saudi Arabia. The study aquifer is called a Quaternary aquifer, which is composed of gravel, sand, sandstone, and intercalated with some shale. In this study, 80 groundwater samples have been collected and analyzed for major ions and 30 representative samples were analyzed for Oxygen-18 (δ18O) and Deuterium (δD). NETPATH and environmental isotopes were integrated and applied to study the overall geochemical processes and to identify the salinity source in the groundwater. Saturation indices calculated for carbonates minerals indicates that 49%, 74%, and 61% of groundwater samples are undersaturated in terms of calcite, aragonite, and dolomite minerals, respectively. The remaining groundwater samples (51%, 39%, and 26%) are close to saturation with calcite, dolomite, and aragonite minerals, respectively. The saturation indices of gypsum, anhydrite, silica, strontionite, and sepiolite minerals show undersaturation in all groundwater samples, which is likely due to the dilution through the groundwater recharge from the surface runoff. In this study, water-rock interaction models were employed with the concentration of major ions of all selected groundwater samples, in addition to reference waters such as rain and sea waters, to evaluate the chemistry of groundwater in the flow path. Mixing calculations suggested that there is a variable contribution of rainwater (5% to 53%) in groundwater samples. The results indicate that evaporation and infiltration have a major impact on water chemistry in the study site. The intrusion of seawater at the coastal zone is well identified in some wells. Stable isotope data (δ18O and δD) support the results and underline the impact of evaporation processes on the groundwater and infiltration of evaporated water.

Assessing the changes in river water quality across a land-use change (forest to oil palm plantation) in peninsular Malaysia using the stable isotopes of water and nitrate

Land conversion from natural forests to plantations (e.g., oil palm) in Southeast Asia is one of the most intensive land-use changes occurring worldwide. To clarify the effects of oil palm plantations on water quality, we conducted multipoint river and stream water sampling in peninsular Malaysia at the end of the rainy season over a 3-year period (2013–2015). We measured the major dissolved ions and stable isotope ratios of water (δ2H-H2O and δ18O-H2O) and nitrate (δ15N-NO3− and δ18O-NO3−) in water from the upper streams in mountainous forests to the midstream areas of two major rivers in peninsular Malaysia. The electrical conductivity increased, and the d-excess value (as an index of the degree of evaporation) decreased with increasing distance from the headwaters, suggesting the effect of evaporative enrichment and the addition of pollutants. We separated the sampling points into four groups (G1–G4) through cluster analysis of the water quality data. From the land use/land cover (LULC) classification maps developed from satellite images and local information, we found that G1 and G2 mainly consisted of sampling points in forested areas, while G3 and G4 were located in oil-palm-affected areas. The concentrations of major ions were higher in the oil palm areas, indicating the effects of fertilizer and limestone (i.e., pH adjustment) applications. The dissolved inorganic nitrogen concentration did not differ among the groups, but the dissolved organic carbon, total dissolved nitrogen, and δ15N-NO3− were higher in the oil palm area than in the forested area. Although the nitrogen concentration was low, even in the oil palm area, the significantly higher δ15N-NO3− in the oil palm area indicated substantial denitrification. This implies that denitrification contributed to the lowering of the NO3− concentration in rivers in the oil palm area, in addition to nutrient uptake by oil palm trees.

Chemical composition and trophic status of urban lakes of the Arctic zone of the Russian Federation (Murmansk)

Chemical composition and trophic status of urban lakes of the Arctic zone of the Russian Federation (Murmansk)

Enhanced sulfide oxidation by monsoon rainfall in a small typical karstic catchment of Southwest China

CO2 is released to the atmosphere via sulfuric acid weathering of carbonate rocks, affecting the flux of CO2 drawdown via silicate weathering. Precisely quantifying the proportion of oxidative weathering of sulfide minerals to riverine sulfate is critical to improving the estimation of the global carbon budge. Sulfur and oxygen isotopic compositions of sulfate and major ion concentrations in river water samples collected monthly at 12 sampling sites from a small typical karstic catchment of Southwest China were analyzed, in order to quantify the relative contribution of sulfide oxidation to riverine sulfate and elucidate the factors affecting its changes. Results show that the sulfate concentration and δ34Ssulfate and δ18Osulfate values at most sampling sites have obvious seasonal changes, with low values in the monsoon season and high values in the non-monsoon season, suggesting that the relative contributions of different sulfur sources to riverine sulfate are seasonally variable throughout of the year. Results from the Beyesian isotope mixing model show that overall, the fraction of sulfide-derived sulfate to riverine sulfate ranges from 44.3 ± 13.7% to 53.3 ± 10.5%, although it has a wide range for different sampling sites. In addition, the relative contribution of sulfide weathering displays a seasonal variation and is higher in the monsoon season, which is mainly attributed to the influence of high rainfall in wet season. This study indicates that an increase in rainfall intensity under climate change may lead to a raised sulfide oxidation rate in the karstic catchment, which is important for assessment of global carbonate and silicate weathering in future.

Salinity-induced ionoregulatory changes in the gill proteome of the mayfly, Neocloeon triangulifer

Ecologists have observed declines in the biodiversity of sensitive freshwater organisms in response to increasing concentrations of major ions (salinization). Yet, how changing salinities physiologically challenge aquatic organisms, such as mayflies, remains remarkably understudied. Moreover, it is not well understood the degree to which species respond and acclimate to salinity changes. Our lab is developing the Baetid mayfly, N. triangulifer, as a model organism for physiological research. We have previously described acclimatory changes in both ion flux rates and altered mRNA transcript levels in response to chronic exposures to elevated major ion concentrations at the whole animal level. In the present study, we use shotgun proteomics to identify the specific proteins associated with apical ion transport and how their abundance changes in response to chronic salinity exposures in gills. Gills were isolated from the penultimate nymphal stage of N. triangulifer reared under control culture conditions, elevated NaCl (157 mg L−1 Na), elevated CaCl2 (121 mg L−1 Ca), elevated Ca/MgSO4 (735 mg L−1 SO4). These conditions mirrored those from previously published physiological work. We also acutely exposed nymphs to dilute (50% dilution of culture water with deionized water) to explore proteomic changes in the gills in response to dilute conditions. We report 710 unique peptide sequences among treatment groups, including important apical ion transporters such as Ca-ATPase, Na/K ATPase, and V-ATPase. Treatment with elevated NaCl and Ca/MgSO4 appeared to cause more significant differential protein expression (452 and 345, respectively) compared to CaCl2 and dilute groups (134 and 17, respectively). Finally, we demonstrated the breadth of physiological functions in gills by exploring non-transport related pathways found in our dataset, including ATP synthesis, calcium signaling, and oxidative stress response. We discuss our results in the context of freshwater salinization and the challenges of working with non-model species without fully sequenced and annotated genomes.

Discriminant model and hydrogeochemical processes for characterizing preferential flow paths in four interconnected volcanic aquifers in Costa Rica

The volcanic Barva and Colima multiaquifer system is crucial for the drinking water supply of about 1.7 million people, about 30% of the population in Costa Rica. The complexity of this system and the simultaneous occurrence of anthropogenic and natural processes complicate the understanding of hydrochemical and hydrogeological dynamics, both essential for groundwater protection. This research aimed to develop a model for the discrimination of groundwaters according to the main withdrawn aquifer and flow path, assess interaquifer connections, and evaluate the main hydrochemical processes governing water quality. Samples (571) from 38 sampling sites, collected quarterly from 2016 to 2020, were analyzed for nitrate, major ions, and silica. Principal component analysis and discriminant analysis exhibited and validated sample grouping according to the primary aquifer system captured, i.e., Upper Barva, Lower Barva, Upper Colima, and Lower Colima, and the occurrence of two flow paths within the Lower Barva and Upper Colima aquifers. Hydrochemical and statistical analyses showed resilience to seasonal chemical variation in deeper aquifers and also three groundwater mixing processes. Lower Barva groundwater enriches in bicarbonate, magnesium, calcium, sodium, and silica, mainly due to weathering of mafic andesitic-basaltic lavas. The Upper and Lower Colima showed higher silica and major ion content, except for calcium, indicating longer residence times, dissolution from felsic andesitic minerals, and calcium adsorption by normal ion exchange. Weathering of aluminosilicates is the primary process governing groundwater quality in the four studied aquifers, whereas cation exchange, interaquifer leakage, and anthropogenic processes might modify the groundwater chemistry.

Study on water inrush pattern of Ordovician limestone in North China Coalfield based on hydrochemical characteristics and evolution processes: A case study in Binhu and Wangchao Coal Mine of Shandong Province, China

Groundwater plays a critical role in the mining areas, providing water for human activities and the growth of animals and plants, but also the main object of mine water disaster prevention. A study on hydrochemical characteristics and evolution in the process of mine water inrush has important practical significance for accurately identifying mine water inrush sources. In this study, the water samples of Ordovician limestone water, the 14th limestone water, and inrush water in Binhu and Wangchao Coal Mines of Tengxian Coalfield were collected. The water samples were compared and analyzed to reveal the variation characteristics of major ion concentration and hydrochemical evolution mechanism during floor cracking-Ordovician limestone water inrush. The results indicated that the type of Ordovician limestone water is Cl-Ca type, the 14th limestone water is Mixed type, and all inrush water is Cl-Na type. Na+(K+) is negative with Ca2+ and Mg2+, while Ca2+ is positive with Mg2+. Hydrochemical analysis showed that the degrees of cation exchange in groundwater are inrush water > the 14th limestone water > Ordovician limestone water, and the average cation exchange contents △C(K++Na+) c are 30.85 meq/L, 9.90 meq/L, and 8.10 meq/L, respectively. Cation exchange significantly changed the Ca2+(Mg2+) and Na+(K+) levels in an aqueous solution during water inrush from Ordovician limestone. The concentration of Ca2+(Mg2+) decreased, while the concentration of Na+(K+) increased significantly and finally formed inrush water with high Na+(K+) and low Ca2+(Mg2+) levels. The saturation index (SI) indicated that the minerals CaCO3, CaMg(CO3)2, and CaSO4.H2O are in oversaturation, the cation exchange results in the decreasing Ca2+(Mg2+), and the SI value is limestone water > the 14th limestone water > inrush water. The cluster analysis (CA) results also showed that considering the effect of cation exchange on the ions concentration of groundwater, the Ordovician limestone, the 14th limestone water, and inrush water samples have the same source in the study area. Overall, The cation exchange significantly affects groundwater ion concentration in the process of Ordovician limestone water inrush. These findings provide a new insight into the hydrochemical evolution mechanism of groundwater and reveal the evolution pattern of Ordovician limestone water inrush in the North China Coalfield.

Impaired cell growth under ammonium stress explained by modeling the energy cost of vacuole expansion in tomato leaves.

Ammonium (NH4 + )-based fertilization efficiently mitigates the adverse effects of nitrogen fertilization on the environment. However, high concentrations of soil NH4 + provoke growth inhibition, partly caused by the reduction of cell enlargement and associated with modifications of cell composition, such as an increase of sugars and a decrease in organic acids. Cell expansion depends largely on the osmotic-driven enlargement of the vacuole. However, the involvement of subcellular compartmentation in the adaptation of plants to ammonium nutrition has received little attention, until now. To investigate this, tomato (Solanum lycopersicum) plants were cultivated under nitrate and ammonium nutrition and the fourth leaf was harvested at seven developmental stages. The vacuolar expansion was monitored and metabolites and inorganic ion contents, together with intracellular pH, were determined. A data-constrained model was constructed to estimate subcellular concentrations of major metabolites and ions. It was first validated at the three latter developmental stages by comparison with subcellular concentrations obtained experimentally using non-aqueous fractionation. Then, the model was used to estimate the subcellular concentrations at the seven developmental stages and the net vacuolar uptake of solutes along the developmental series. Our results showed ammonium nutrition provokes an acidification of the vacuole and a reduction in the flux of solutes into the vacuoles. Overall, analysis of the subcellular compartmentation reveals a mechanism behind leaf growth inhibition under ammonium stress linked to the higher energy cost of vacuole expansion, as a result of alterations in pH, the inhibition of glycolysis routes and the depletion of organic acids.

Hydrogeochemical characteristics and solute sources of groundwater in the Yuhengbei mining area, Shaanxi Province, China

In mining areas, groundwater resources are crucial for providing drinking water, as well as water needed for plant growth and mining. The Yuhengbei mining area is situated in arid and semi-arid areas in Western China. As there are a number of large-scale mining fields in the area, their exploitation may affect both the quality and quantity of groundwater. The hydraulic connection between aquifers directly determines whether deep coal mining activities affect water quality in shallow aquifers. This study investigates the hydrogeochemical characteristics and the solute sources of groundwater (including surface water, Quaternary water, water from Cretaceous and Jurassic coal strata aquifer) in the Yuhengbei mining area. The study uses conventional, multivariate statistical analysis, and dissolved organic matter (DOM) analysis. The results suggest that all water samples were slightly alkaline, while the water from the shallow aquifers (surface water, Quaternary and Cretaceous aquifers) was predominantly of the HCO3-Ca type. Furthermore, the groundwater in the deep Jurassic aquifer was mostly of the SO4-Na type. Major ion and DOM concentrations appeared to decrease with increasing aquifer depth. Moreover, the groundwater circulation is regulated by natural processes. Namely, rock weathering was the main mechanism controlling the chemical constituents of groundwater in the shallow aquifers, while groundwater quality in deep aquifers was mainly governed by the dissolution of evaporation. Water–rock interaction and cation exchange were the main mechanisms controlling the chemical constituents of groundwater. The R-mode HCA revealed that natural processes controlled the chemical composition of groundwater, as well as that the evolution of groundwater is primarily controlled by the nature of the geological structures and the local hydrogeological conditions. The TOC and UV254 results suggest that the coal strata aquifer had a weak hydraulic connection with the overlying aquifers. The DOM was mainly derived from autogenous biological sources. Based on the indicator values, the hydraulic connection between the deep aquifers and the upper shallow aquifers was weak overall. These results show that in this area, although drinking water and irrigation water come predominantly from shallow groundwater, mining activities temporarily have little impact on the quality of shallow groundwater. Better understanding hydrogeochemical characteristics and formation mechanisms will provide a technical basis for local groundwater management and support the sustainable use of water resources.