Dominant Cation Research Articles

Integrated study of hydrochemistry, quality and risk to human health of groundwater in the upper reaches of the Wulong River Basin.

Groundwater, a vital source of water supply, is currently experiencing a pollution crisis that poses a significant risk to human health. To understand the hydrochemical formation mechanisms, quality and risk to human health of groundwater in the upper reaches of the Wulong River basin, 63 sets of groundwater samples were collected and analyzed. A combination of mathematical statistics, correlation analysis, Gibbs diagram, ion ratio, and cation exchange were comprehensively employed for hydrochemical analysis, and further water quality index (WQI) and human health risk assessment were conducted. The results indicate that groundwater is generally neutral to weakly alkaline. The dominant cations in the groundwater are Ca2+ and Mg2+, while the main anions are HCO3- and SO42-. The hydrochemical types of groundwater mainly include HCO3·SO4-Ca, HCO3-Ca and HCO3-Na. The diverse hydrochemical types are mainly due to the fractured and discontinuous nature of the aquifers. The hydrochemical characteristics are influenced by the dissolution of silicate and carbonate minerals, cation exchange processes, and anthropogenic pollution. The presence of NO3- in groundwater is primarily attributed to agricultural activities. The groundwater is mainly categorized as "Good" (36.6%) and "Poor" (60.8%). "Very poor" and "Excellent" categories are rare, accounting for only 1.2% and 1.4%, respectively, and no samples are classified as "Non-drinkable". The Ewi for NO3- is the highest, indicating severe contamination by anthropogenic NO3- pollution. Human health risk assessment reveals that water samples posing exposure risks account for 82.54% for children and 79.37% for adults. This study highlighted that anthropogenic nitrate pollution has deteriorated groundwater quality, posing risks to human health. It also suggests an urgent need to enhance research and protective measures for groundwater in similar regions, such as the Shandong Peninsula.

The repeatability of reusing peat as horticultural substrate and the role of fertigation for optimal reuse

Direct reuse of horticultural substrates may facilitate the transition from linear to circular greenhouse cultivation. Characteristics of spent growing media from strawberry cultivation were compared to substrates from ornamentals, mushrooms, microgreens, and greenhouse vegetables. Direct reuse of spent peat as a stand-alone material was tested in three trials under commercial conditions. In the first trial strawberry cultivation on reused growing media with included crop residues resulted in similar yield as for virgin blends in a spring cultivation. In the second trial repeated reuse of spent growing media was tested in an autumn cultivation, either with direct reuse or with reuse after shredding and steam treatment for sanitation. Nutrient retention did not increase further during repeated reuse. Yield was similar to virgin peat for the direct reuse and steam sanitation treatments. Under reuse deterioration in terms of physical properties was not observed. Biological stability remained high for all media during reuse. Reusing peat for strawberry 3 times did not lead to any problems for yield or substrate. In the third trial the effects of fertigation regimes with reduced P and K input on nutrient retention during direct reuse in a spring cultivation were limited. In contrast, significantly lower N, P, K, Mg and Ca contents in the substrate were measured when fertigation was replaced by water in the last two weeks of the cultivation. Cation exchange capacity in the spent peat in all trials remained high during reuse. Ca was the dominant cation on the exchange complex.

A 2‐Billion‐Year History of Water‐Alteration in Terra Sirenum, Mars: Volcanism's Influence on Aluminum Clay Formation and Chemically Distinct Waters Forming Sulfates and Chlorides Into the Amazonian

AbstractTerra Sirenum, a region of Noachian highlands southwest of the Tharsis volcanic complex, is unique in the number, proximity, and diversity of orbital detections of secondary minerals, as the sole region found to date hosting large‐scale deposits of all of Mars' major salts (chlorides, sulfates, carbonates) as well as diverse hydrated silicates. We combine mineralogical information, high‐resolution imagery, and elevation models to investigate the geologic context of these secondary minerals to understand the sources of water and ions for each type of deposit and their spatial/temporal relationships. Carbonates, where present, are part of Noachian basement rocks exposed through cratering and do not appear associated with evaporative sequences. Numerous small detections of the acid sulfate minerals alunite and jarosite mirror the dominant clay cation in the localities they are found—Al phyllosilicates and Fe phyllosilicates, respectively—suggesting in situ formation. We interpret a previously discovered kaolinite‐rich unit overlying Fe/Mg clays across northeast Terra Sirenum as remnants of a widespread ash unit rather than a pedogenic weathering sequence. Sulfate and chloride detections are decoupled, with sulfates in topographic lows likely precipitated from volcanism‐associated groundwaters, while chloride detections are consistent with surface water runoff, in some instances clearly post‐dating volcanic units capping sulfate detections. Volcanic resurfacing of craters in the region is progressively younger from west to east, and crater statistics‐based ages indicate localized sulfate‐ and chloride‐forming processes continue to occur from ∼3.5 to ∼1.4 Ga. We hypothesize that their decoupling points to disconnected, episodic surface and groundwater reservoirs, perhaps separated by a permafrost layer.

Hydro-Geochemistry and Water Quality Index Assessment in the Dakhla Oasis, Egypt

Water quality is crucial to the environmental system and thus its chemistry is important, and can be directly related to the water’s source, the climate, and the geology of the region. This study focuses on analyzing the hydrochemistry of specific locations within the Dakhla Oasis in Egypt. A total of thirty-nine groundwater samples representing the Nubian Sandstone Aquifer (NSSA) and seven surface water samples from wastewater lakes and canals were collected for analysis. Key parameters such as pH, electrical conductivity (EC), and total dissolved solids (TDS) were measured on-site, while major ions and trace elements (Fe+2 and Mn+2) were analyzed in the laboratory. The water quality index (WQI) method was employed to assess the overall water quality. Hydro-chemical facies were investigated using Piper’s, Scholler’s, and Stiff diagrams, revealing sodium as the dominant cation and chloride, followed by bicarbonate as the dominant anion. The hydro-chemical composition indicates that Na–Cl constitutes the primary water type in this study. This points to the dissolution of evaporates and salt enrichment due to intense evaporation resulting from the region’s hyper-aridity. In groundwater samples, the order of hydro-chemical facies is HCO3− > Cl− > SO4−2 > Na+ > Ca+2 > K+ > Mg+2, while in wastewater samples, it is Cl− > Na+ > SO4−2 > HCO3− > Ca+2 > Mg+2 > K+. When considering iron and manganese parameters, the water quality index (WQI) values suggest that most groundwater samples exhibit excellent to good quality but become poor or very poor when these elements are included. This study could prove valuable for water resource management in the Dakhla Oasis.

Features of the formation of natural-technical systems within the injection areas of the Daldyn kimberlite field (Western Yakutia)

Relevance. Primary diamond deposits mined by PJSC ALROSA in Western Yakutia have widespread watering of varying intensity with sub-permafrost and inter-permafrost strong and very strong brines. Currently, the resulting drainage waters are pumped back into the depths of the permafrost, which leads to the formation of natural-technogenic aquifers that require constant control, monitoring and study. Aim. Identification of the features of the formation of natural-technogenic systems within the injection areas of the Daldyn kimberlite field, determination of the volume of permafrost waters involved in this process, as well as their characteristics to confirm the environmental friendliness of the method of handling drainage brines. Methods. Field work consisted of quarterly routine testing of observation and injection wells. Assessment of technogenic influence, as well as subsequent forecasting of the dynamics of changes in cryohydrogeological conditions and hydrodynamic regime, was carried out using modeling methods in Feflow software. An additional method was analytical balance calculation based on the parameter of changing mineralization. Results and conclusions. The interaction of drainage waters with permafrost waters leads to areal changes in mineralization without significant changes in the dominant anions and cations within the studied objects, forming an equilibrium natural-technogenic system in the peripheral parts relative to background temperature conditions. The volume of formed man-made aquifers will exceed 300 million m3. The process of involving cryogenic waters, despite the significant volumes, has a positive impact on the ecological state of the territory, because in the peripheral parts of the resulting aquifers, equilibrium cryohydrogeological conditions are formed, characteristic of natural cryopegs in the region of study.

Evaluation of land use and geological effect on groundwater characteristics in Bandung metropolitan using a hydrochemical and statistical approach

Abstract Groundwater is often used as clean water since it requires less water treatment. However, the quality will depend on the environmental conditions and human activities. Our research is conducted in Bandung Metropolitan, an urbanized area where groundwater is preferable, but the quality is becoming concerning. The objective of this study is to determine whether natural or human activities have a greater impact on groundwater quality. A total of 113 samples were collected from nine geological conditions spanning three primary land use types. The samples were analyzed for seven major ions (Na+, K+, Ca2+, Mg2+, HCO3 −, SO4 2 −, and Cl−), which occur naturally in natural water but may be elevated due to human activities. Based on the Piper diagram, fifty-three samples are categorized as Ca-HCO3, with the dominant cation being Ca2+ and the dominant anion being HCO3 −. Furthermore, the multivariate statistical analysis reveals that 74% of all ions are related to geological conditions and anthropogenic activities. In detail, high contents of Ca2+, as the dominant cation, are significantly correlated by all land uses and most geological formations. In addition, cation contents were significantly correlated with land uses, but the correlation varied for each type of geological formation. All land uses surely correlate with all major ions, but the geology depends on the type of formation.

Characterization and potential toxicity of asbestiform erionite from Gawler Downs, New Zealand

Abstract Erionite is the name for a zeolite mineral series originating from diagenesis or hydrothermal alteration of volcanic rocks. The particular erionite “species” is based on the dominant extra-framework cation, erionite-Ca, erionite-K, or erionite Na. Irrespective of the species, erionite can display a fibrous/asbestiform morphology and has been linked with cases of malignant mesothelioma, a disease typically associated with asbestos exposure. Characterization of new discoveries of erionite is therefore important to assess any potential exposure hazards. This study describes a new asbestiform erionite from vesicles within the Upper Cretaceous Mt. Somers Volcanics Group (MSVG), Canterbury, New Zealand. The erionite is within the Hinds River Dacite, the youngest unit within the MSVG at Gawler Downs, ~100 km west of Christchurch, in the foothills of the Southern Alps. A multi-analytical approach was taken to analyze the sample which included micro-Raman spectroscopy, thermogravimetric analysis, electron microscopy, electron microprobe analysis, and X-ray powder diffraction with the Rietveld method. Results confirmed the mineral as fibrous erionite-K. The chemical composition of the mineral is unique due to the presence of higher levels of Mg. While Fe was also identified, this was due to smectite flakes occurring on the surface of the erionite fibers. According to the World Health Organization (WHO) respirable mineral fiber definition, where length ≥5 μm, width ≤3 μm, and aspect ratio (L/w) ≥3:1, the Gawler Downs erionite fibers are respirable, while the fibers themselves exceed respirable thickness. In addition to morphology, a value for the potential toxicity model was computed to be 2.28 for the Gawler Downs erionite. This is similar to those of other carcinogenic erionites from Karain, Turkey (2.33), and Nevada, U.S.A. (2.28). Taken together, results indicate Gawler Downs erionite represents an environmental hazard. Nevertheless, further investigation is required to determine potential environmental exposure pathways by which erionite may become airborne and assess the actual environmental risk in the Gawler Downs area.

Analysis of the evolution and causes of groundwater chemistry after ecological water replenishment of the Jialu River, China

Ecological water replenishment is an important measure for conserving water sources and improving the water environment. To explore the evolution and causes of groundwater chemistry after ecological water replenishment in the Jialu River, this study utilized groundwater monitoring data from 2015 to 2019 following ecological water replenishment. Various methods, including Piper’s trilinear diagram, Gibbs diagram, principal component analysis, and ion ratio analysis, were employed for research purposes. The results indicate that (1) since the implementation of ecological water replenishment in the Jialu River, there has been a general downwards trend in total dissolved solids (TDS) in groundwater. The dominant cation in groundwater is Ca2+, whereas HCO3− is the dominant anion. The concentration of cations in groundwater has generally decreased, with noticeable reductions in SO42− and Cl− concentrations in the upper reaches of the recharge river contributing to improved groundwater quality. (2) A comparison with 2015 reveals a gradual transition at sampling points from chemical types such as HCO3-Ca·Mg and HCO3·Cl–Ca·Mg to an ecological water replenishment chemical type (HCO3-Ca).

Montmorillonite Clay-Based Electrocatalyst for Water Splitting Applications

The goal of reaching net-zero emissions by the year 2050 requires a strategic overhaul to be realistically achievable. Hydrogen energy is considered an ideal substitute for fossil fuels, which leave carbon footprints and release hazardous chemicals into the atmosphere. Thus, large-scale commercialization of hydrogen energy could meet future energy demands with zero emissions. Electrochemical water splitting (EWS) is the most sustainable and efficient method to produce hydrogen for the next century. Thus, designing an electrocatalyst with an enhanced surface structure and abundant earth materials makes it a highly adoptable and affordable green energy. Smectite clay minerals are abundant on earth, non-hazardous, and easy to fabricate due to their clay nature. Among the smectites, montmorillonite is a promising candidate for electrocatalysts due to its unique physicochemical properties like expandable layered structure (TOT layers), high cation exchange, water adsorption, and swelling properties. Due to the high cationic exchange capacity of montmorillonite clays (70-110 meq/100g), the structural and interlayer cations can be tuned according to the water adsorption and desorption properties. When we look into the mineral structure, montmorillonite smectites belong to 2:1 phyllosilicate-layered sheets, composed of two tetrahedral silicate sheets (T) and one octahedral sheet (O). In each layer, an octahedral sheet is sandwiched between the two tetrahedral sheets (TOT), which is shown in Figure a. In the tetrahedral sheets, the dominant cation is Si4+, which is often substituted by the trivalent cation Al3+. The isomorphic substitution of Si4+ by Al3+ in the tetrahedral layer raises charge deficiency in the tetrahedral sheet, which is balanced by the absorbed interlayer cations like K+, Na+, and Ca2+ between the water molecules. In octahedral sheets, the common cations are Al3+, Mg2+, Fe3+, or Fe2+, and other cations like Ni2+, Li2+, and Cr2+. When the Mg2+ ions are substituted by Al3+ ions, it gives rise to a positive charge in the octahedral sheet. Depending upon the charges within the tetrahedral and octahedral sheets, the layered structure properties are altered. By considering their cation-rich and expandable properties, we have employed montmorillonite clay materials [Na,Ca)0.3 (Al,Mg)2 Si4O10(OH)2. nH2O] in electrocatalytic water splitting reactions for the first time. In our observation, annealing the montmorillonite at high temperatures such as 300 oC (Mont300/NF), 600 oC (Mont600/NF), and 900 oC (Mont900/NF), reconstruct the surface, and induce structural defects, which enables isomorphic substitution of bivalent (M2+) or trivalent cations (M3+). The annealed samples were prepared as slurry using binder additives (PVDF and NMP solvent) and coated on nickel foam (NF). The electrochemical performance was tested in a three-electrode potentiostat system in 1M KOH electrolyte, where the prepared sample was employed as the working electrode, graphite rod as the counter electrode, and Hg/HgO as the reference electrode. Figure b and c shows the electrochemical performances of the HER and OER reactions. Initially, the Mont600/NF catalysts show lower overpotential of 178 mV and 250 mV at 10 mA/cm2 for HER and OER reactions respectively. The pristine sample (Mont/NF) show much higher overpotential (240 mV for HER and 360 mV for OER). Thus, annealing promotes the formation of dangling bonds by generating cationic and anionic vacancies, which act as active sites for the adsorption of intermediates, which in turn reduces the requirement for higher overpotential. Furthermore, the pristine montmorillonite is mixed with functionalized CNT powder and annealed at the best performing temperature of 600oC (Mont+CNT600/NF). As a result, Mont+CNT600/NF sample shows much higher performance than Mont600/NF by requiring lower overpotential of 168 mV and 220 mV at 10 mA/cm2 for HER and OER reflecting the higher intrinsic kinetics owing to increased electrical conductivity due to CNT which enhances the electron transport properties and the water splitting kinetics. Interestingly, the used clay materials can be treated with organic solutions and can be reused due to their physicochemical retaining properties even after being treated at high temperatures. This would reduce the amount of solid catalyst waste going into landfills. Therefore, montmorillonite clay materials are the new era of catalyst’s material with recyclability due to their self-retaining physicochemical properties, water hydration, and dehydration properties. In this work, we have successfully optimized the montmorillonite properties by annealing at high temperatures, which helps to reconstruct the surface by breaking the OH lattice ions and creating dangling bonds. The formation of dangling bonds increases the rate of water splitting processes by acting as a surface-active site for the adsorption and desorption of H+ and OH- ions. Thus, tuning montmorillonite clays helps in achieving different water splitting properties. Figure 1

Groot Aub groundwater quality and its suitability for domestic purposes, Namibia

The Groot Aub (GA) settlement depends entirely on groundwater for domestic purposes and other development activities. Development activities are mainly agriculture, such as animal husbandry, chicken farming and crop farming using irrigation. However, these activities have the potential to contaminate the groundwater system. A total of 87 groundwater samples were collected from the boreholes in the study area during the dry and wet season. Water quality parameters (pH, salinity, total dissolved solids (TDS), electrical conductivity (EC) and hydrochemistry (Na+ > Ca2+ > Mg2+ > K+, and HCO3− > SO42− > Cl−) of 5 boreholes and 1 reservoir tank were analysed. The dominant cations were attributed to cation exchange processes as a coupled exchange of Na+ + K+ replacing Ca2+; and Na+ replacing Mg2+ ions in the rock–water interactions. The HCO3− anion is attributed to underlying rich carbonate rocks in the study area and chemical reactions between groundwater and silicate minerals. TDS ranged from 639.01 to 1 998.96 mg/L. The microbial levels as indicated by heterotrophic plate count (HPC) values exceed the limits imposed by the local Namibian and WHO drinking water regulations. The Piper diagrams showed a mixed water type of mainly HCO3− and SO42− anions and Na+ and Ca2+ > Mg2+ cations. The study shows that the elemental composition of the groundwater is impacted significantly by primarily anthropogenic activities and secondarily geogenic processes. Based on the results of this study it is recommended that a buffer zone be created between human activities and production boreholes to avoid further groundwater contamination.

Hydrochemical Characteristics and Controlling Factors of the Mingyong River Water of the Meili Snow Mountains, China

The hydrochemical characteristics of rivers are affected by many natural factors, such as the nature of watershed bedrock, watershed environment, vegetation, and human activities. Examining the hydrochemistry of a river can provide insights into the baseline hydrological conditions, the geochemical environment, and the overall water quality of the river. In order to examine the hydrochemical characteristics and controlling factors of the water in the Mingyong River, a total of 154 water samples were gathered from the glacier meltwater, midstream, and downstream regions. Firstly, the findings revealed that the dominant cations are Ca2+ and Mg2+, while the dominant anions are HCO3− and SO42−. The mass concentration order of cations is Ca2+ > Mg2+ > Na+ > K+, and for anions, it is HCO3− > SO42− > NO3− > Cl−. The average concentration of TDS in the river water is 81.69 mg·L−1, with an average EC of 163.63 μs·cm−1 and an average pH of 8.99. Temporal variations in ion concentrations exhibit significant disparities between the glacier melting and accumulation periods. High ion concentration values are primarily observed during the glacier accumulation period, while values decrease during the glacier melting period due to increased precipitation. The river water in the study region is categorized as (HCO3− + SO42−)-(Ca2+ + Mg2+) type. Secondly, the Pearson correlation analysis indicates clear relationships between different parameters, indicating that the major ions were mostly influenced by materials from the Earth’s crust. The primary principal source of solutes in the water of the Mingyong River is rock weathering. The cations and anions present in the river water are derived from the breakdown of carbonate rocks and the dissolving of substances from silicate rocks. However, the influence of carbonate rocks is more significant compared to that of silicate rocks. Finally, the Mingyong River water is suitable for agricultural irrigation with minimal land salinization damage, making it appropriate for agricultural purposes but not suitable for people and animals to drink from directly.

Morphological and Physico-chemical Properties of Soils of Amtur-3 Micro-Watershed on Schistose Landscape in Bailhongal taluk of Belagavi District, Karnataka, India

Aims: To assess the morphological and physico-chemical properties of two soil series viz., KKT (Kabulayathkatti tanda) and SDH (Singadahalli) of Amtur-3 micro-watershed developed on schistose landscape in northern transition zone of Karnataka. Place and Duration of Study: The study was carried out in the Amtur-3 micro-watershed (4D5B8t04) located in Bailhongal taluk of Belagavi district, Karnataka during 2022-2024. Methodology: Horizon-wise soil samples were collected from the two representative pedons viz., KKT (Kabulayathkatti tanda) and SDH (Singadahalli) soil series, were identified, characterized and classified up to family level according to revisions in Soil Taxonomy using morphological, physical and chemical properties. Results: The soils of these two series were sandy clay loam to clay in texture, neutral in soil reaction and had low salt content. Calcium and magnesium were the dominant cations followed by sodium and potassium. Both the soil series belonged to the order Inceptisol.

Hydrochemical characterization and health risk assessment of different types of water bodies in Fenghuang Mountain Area, Northeast China.

Groundwater, as an essential resource, holds significant importance for human production and livelihoods. With the deterioration of the water environment, the issue of groundwater quality has become an urgent international concern. This study focused on the Fenghuang Mountain Area (FMA) and collected a total of 41 sets of samples including pore groundwater (PGW), fissure groundwater (FGW), karst groundwater(KGW), and river water(RW). Hydrochemical analysis methods were employed to identify the hydrochemical characteristics and controlling factors. The entropy-weighted water quality index (EWQI) and health risk assessment model were utilized to assess the groundwater quality and nitrate health risk, respectively. The results indicated that the dominant anion and cation in both groundwater and surface water in the FMA were HCO3- and Ca2+, respectively, with the main hydrochemical type being HCO3-Ca. Groundwater and surface water in the FMA were primarily controlled by rock weathering process, with ion concentrations influenced mainly by the dissolution of halite, sylvite, carbonates (calcite and dolomite), silicates, and gypsum, as well as by reverse anion exchange process. PGW was significantly affected by agricultural activities, with NO3- concentration closely related to human activities. The water quality of FGW was relatively good, with Class I and Class II water accounting for the highest proportion, reaching 84.62%. The high-value area of EWQI in PGW was influenced by human activities. The impact of nitrate health risk on children was significantly greater than on adults, with FGW having the lowest health risk and PGW having the highest health risk. The research results can provide important guarantees for the rational development and utilization of water resources in the FMA and the sustainable development of the economy in Northeast China.

Hydrochemical Characteristics, Controlling Factors and Water Quality Evaluation of Groundwater Quality in Kono, Sierra Leone

Groundwater is a major source of drinking water and is considered an imperative component of the accessible water assets across Sierra Leone and many parts of the world. The degradation of groundwater can jeopardize drinking water availability and human health. 29 groundwater monitoring samples with 16 water quality parameters were analyzed. Descriptive statistics, Piper plots, Arc GIS spatial interpolation, Gibbs plots, ion ratio analysis, Wilcox diagram, water quality index (WQI), and entropy-weighted water quality index (EWQI) were used to investigate the hydrochemical characteristics, controlling factors and evaluate the groundwater quality in the study area. The results revealed that the groundwater mean concentration of NO3− in the mining concession was 34.00 mg/L which was above the permissible limit, Ca2+ and HCO3− are higher in the Koidu community compared to the mining concession water, indicating weakly alkaline with dominant anions and cations of HCO3− and Na+ + K+ respectively, and the hydrochemical types were mainly HCO3−·Ca2+ and HCO3− ·Na+. The order of anion concentration in groundwater was HCO3− > NO3− > SO42− > Cl− and HCO3− > SO42− > NO3− > Cl− in the mining concession and the Koidu community respectively. Cations were Ca2+ > Na+, K+ > Mg2+ > Fe²⁺, and Ca2+ > Na+ > Mg2+ > K+ > Fe²⁺ in the mining concession and the Koidu community respectively. The interpretation of WQI and EWQI analysis exhibits 55.17% excellent, 17.24% good, 20.69% medium, 6.90% very poor, and 27.59% excellent, 24.14% good, 34.48% medium, 3.45% poor, and 10.34% very poor water respectively. Most of the sampling sites display similar trends to the WQI and EWQI. The solute source of groundwater was mainly controlled by water-rock interaction, cation exchange and the weathering of silicate and carbonate rocks were jointly the main contributors to the formation of the chemical components of groundwater in the study area, among which the main controlling factors of the groundwater were leaching, precipitate concentration and anthropogenic activities, and sulfate rock and carbonate rock dissolution. The overall water quality in the study area was suitable for human consumption but was polluted to an insignificant extent by mining activities. This study provides theoretical support and a decision-making basis for developing, utilizing, and protecting water resources in the study area.

Characterization and Mapping of Soil Salinity Status at Small-Scale Irrigation Farm: The Case of Fantale Irrigation Project Sites

Agricultural production and productivity can be adversely affected by the presence of excessive salts in soils particularly in semi-arid and arid areas. Knowledge of the salinity/sodicity of the soil and the quality of the irrigation water is essential for managing agricultural fields effectively and increasing the output and productivity of the lands. This research was initiated with the objectives of characterizing and Mapping of soil salinity status at small scale irrigated areas of Fantale district and identifying the most affected irrigation scheme so as to design appropriate soil salinity management. The study was conducted at Fentale district of Galcha, Gola and Dire Sade irrigation schemes. Soil samples were collected from the surface using augur, and from pits at different depth interval and analyzed for pH, EC, Na+, ESP, SAR, Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup>, and CEC. The result was compared with the standards set by FAO system to classify soil and water salinity. Accordingly, it was identified that Galcha irrigation scheme was characterized as sodic due to very strong sodium concentration with average ESP of 53.2% and EC 3.95 mmhoms/cm and pH about 9.25. On the other hand, Gola and Dire Sade Irrigation schemes were characterized as moderately and slightly sodic respectively. Sodium was the dominant soluble cation, followed by calcium, magnesium, and potassium in all soil depths and schemes. Beside primary Salinization of natural processes such as physical or chemical weathering parent material, and discharge Basaka Lake to the downstream, was the main source of salt build-up in the upper layers of the soil at Galcha irrigation scheme. On the other hand, irrigation water analysis indicated that water used for irrigation at all irrigation schemes were slightly sodic. Therefore, the study underscores the need for a scientific reclamation of sodic soils primarily at Galcha Irrigation scheme where sodium concentration in the soil was very strong.

Hydrogeochemical characteristics of shallow groundwater and salinization evaluation in the coastal aquifers of Cangzhou, China

To investigate the hydrogeochemical characteristics of shallow groundwater and evaluate groundwater salinization state in Cangzhou, China, two sampling campaigns have been conducted. In summer, 33 groundwater samples, 3 seawater samples and 5 river water samples were collected. In winter, 22 groundwater samples were collected. The hydrochemical type was determined by the Piper diagram. Evolution mechanisms of groundwater were analyzed by the Gibbs diagram. The trend of de-salinization or salinization of groundwater was determined by the hydrochemical facies evolution diagram. The groundwater salinization grade was evaluated by both the seawater intrusion groundwater quality index (GQISWI) and the attribute recognition model based on entropy weight (ARMEW). The Piper diagram shows that Na+ is the dominant cation and Cl- is the dominant anion in shallow groundwater, and the groundwater in this area is mainly of Cl-Na type followed by Cl-Ca·Mg type. The evaporation-crystallization process has significant influence on the evolution of saline groundwater. In summer, most brackish groundwater exhibit compositions of the freshening stage with direct cation exchange, and most saline groundwater is mainly at the seawater intrusion stage with reverse cation exchange. In winter, compared to the summer season, more groundwater samples in the middle of study area exhibit intrusion trend, and without obvious Na-HCO3 facies. In summer, values of GQISWI range from 20.47 to 75.38 with an average of 59.31. The GQISWI gradually increases from east to west, denoting the degree of groundwater salinization is alleviated from coast to inland. In winter, values of GQISWI range from 54.47 to 79.09 with an average of 66.00, slightly higher than that in summer. The proportion of no salinization (Grade I), minor salinization (Grade II) and serious salinization (Grade III) of groundwater samples in Cangzhou identified by ARMEW is 3.0%, 21.2% and 75.8% in summer, respectively. In winter, the proportion is 9.1% for Grade II and 90.9% for Grade III. The GQISWI index shows the largest area of Grade II, and ARMEW presents the largest area of Grade III in both seasons. Compared with GQISWI index, ARMEW model gives more conservative evaluation results of groundwater salinization. The results provide useful information on the groundwater salinization status for the local area, and help for the management of groundwater resources in Cangzhou.

Modeling of the particle fluxes of a helium plasma jet onto water surface

The interaction between an atmospheric pressure plasma jet (APPJ) and an aqueous solution has great application prospects in biomedicine and many other fields. Reactive species adjacent to a water surface is critical to the activation of APPJ-treated water, which is affected by both the water evaporation and the admixture of ambient air. In this paper, taking He APPJ as an example, a two-dimensional (2D) cylindrically symmetric fluid model is developed to obtain the spatial distributions of gas components before discharging, and a series of global models are developed for the discharge in the boundary gas layer adjacent to the water surface. The interfacial distributions of reactive species and their fluxes onto the water surface are quantified. It is found that the electron density is 1016–1017 m−3 and it shows an annular distribution in the boundary gas layer. The density distributions of most reactive species there reveal ring-like shapes as well. The dominant cation and anion in such a boundary layer are H3O+ and OH−, respectively. The most abundant metastable is O2(a1Δ), the most abundant reactive oxygen species are H2O2 and OH, and the most abundant reactive nitrogen species are NO and HNO2. The species of H2O2, OH, HO2, and HNO2 are reportedly to have significant biological effects, and in our simulation, their fluxes onto the water surface are remarkable, higher than 1017 m−2 s−1. In addition, the effects of radial gas velocity and water evaporation on the particle flux distributions are also revealed.

Pedological features of a sustainable halophyte wetland: El Hito saline pond (Central Spain)

AbstractIn semi‐arid Mediterranean regions, particularly in some wetland soils, salinity is thought to be an indicator of low‐quality soils. In this study, a characterization is presented of the soils surrounding El Hito saline pond (Castilla La Mancha, Central Spain), an ecological halophyte niche within a natural semi‐arid steppe land. The main aim is to classify the salt‐affected soils and their morphology, genesis, and physico‐chemical properties. Four soil profiles were opened with a backhoe machine for sampling and subsequent description on the basis of their pedogenetic morphology. Systematic surface sampling was also performed. Standard methods were followed to measure the soil properties of 27 samples. Overall electrical conductivity (EC) and pH levels of the wetland were mapped (using ArcGIS 3.1.3). Soil salinity at elevated levels was detected, inhibiting plant uptake of water and nutrients. Distinct sub‐areas of extreme elevated surface salinity providing specialized plant habitats and poor soil structure were observed, as well as a mainly whitened‐yellowish‐greenish soil colour due to salt accumulation and poor drainage. The soils also showed alkaline pH values. In most samples, the pH was over 8.5, and EC was higher than 4 (dS m−1), and in several samples higher than 20 (dS m−1). A low sodium (Na) content was detected in the saturation extract where magnesium (Mg+) was the dominant soluble cation, followed by both calcium (Ca+) and sodium (Na+), and then potassium (K+), present in lower proportions. Sulphate (SO42−) and then chloride (Cl−) anions were dominant, although carbon trioxide, (CO3−) and carbonate (CO32−) anions were also present. The percentages of organic carbon (C) were very low, while total nitrogen (TN) and available phosphorus (P) were higher in the upper horizons, suggesting a degree of eutrophication. The present work will increase the existing knowledge about the role of El Hito saline pond, that play a vital ecological role in the broader biosphere, providing new suggestions to readers on how this knowledge can be used to improve these types of ecosystems. In particular, the agricultural pesticides and fertilizers continuously damage the soil fertility as evidenced by the high content of soluble phosphorus found in some points of the Hito saline pond.

Characterization and Classifications of Soils in an Experimental Farm in the Tiruvannamalai District, Tamil Nadu, India

It is essential to characterize and classify soil resources in order to plan agricultural land use agroforestry, agri-horticulture and silvipastoral farming systems. In the present study, an attempt was made to characterize and classify the soils occurring on different topography in an experimental farm in Tiruvannamalai District of Tamil Nadu, India. A detailed soil survey was carried out using cadastral map. Physiographically, the area has been characterized into Pediplain shallow weathered and Pediplain moderately weathered which were further subdivided based on slope and erosion categories. Six typical pedons were identified based on landform and their soil morphological properties. The soils were very shallow to moderately deep, dark reddish brown to yellowish red (red soils) in colour with sub-angular blocky in structure, These soils were sandy loam to sandy clay loam in texture, slightly acidic to mildly alkaline (3.28-7.70) in reaction (non-saline soils) and had low to medium (1.2 to 6.4 g/kg) organic carbon content. Calcium and magnesium were the dominant exchangeable cations followed by sodium and potassium. Taxonomically these soils were classified as Typic Rhodustalfs, Typic Haplustalfs, Vertic Haplustepts and Typic Haplustepts at the subgroup level.

Snow chemical characteristics and meteorological controlling factors from three snowfalls of Gande in the Tibetan plateau

Water-soluble ions (Cl−, SO42−, NO3−, Ca2+, Mg2+, Na+, K+ and NH4+) and trace elements (Pb, Cd, Cr and As) in snow samples were analyzed from three different snowfall events (Ⅰ, Ⅱ, Ⅲ) in December 2019 at Gande Meteorological Station, located in the southeastern part of the Tibetan Plateau region. From event Ⅰ to Ⅲ, the total concentration of water-soluble ions presented an increasing trend of 0.92, 1.43 and 3.01 mg L−1, respectively. The dominant cation was Ca2+ for all the events, while the dominate anion was SO42−, SO42− and Cl− in the event Ⅰ, Ⅱ and Ⅲ, respectively. Meteorological field and backward trajectory cluster analysis presented three different large-scale predominant wind directions of northwest wind, southwest wind and west wind for each event, revealing different transport processes and sources for snow components. The total concentration of water-soluble ions was mainly related to PM10 as the in-situ PM10 observation showed a similar increasing trend. The dominant trace element was different Pb, Cr and Pb in each event. The mixed source of crustal and industrial inputs was the key factor in three snowfalls, and its contribution was consistent with the concentration of dominant trace element. Herein, high fractions of Pb and Ca2+ were appeared in the event Ⅰ and Ⅲ, but largest proportion to Cr was enhanced in the event Ⅱ.