Hydrochemical Zoning Research Articles

SPATIAL AND TEMPORAL FEATURES OF WATER CHEMISTRY CHANGES IN THE QUATERNARY UNCONFINED AQUIFERS OF THE DNIPRО RIVER BASIN

The article deals with the chemical composition of uppermost aquifers water in the Dnipro River basin. Its study is necessary not only in connection with the implementation the requirements of the EU Water Framework Directive methodological documents in the groundwater monitoring, but primarily because of water supply from these aquifers to rural areas. Unconfined aquifers water is characterized by a complex and heterogeneous chemical composition due to natural and anthropogenic factors. Natural hydrochemical zoning is distinctly visible on the territory of the Dnipro basin. A number of chemical elements and compounds in the water are contained in concentrations exceeding the standards for drinking water established by the State sanitary norms and rules 2.2.4-171-10 “Hygienic requirements for drinking water intended for human consumption” in the natural state. In addition, unconfined aquifers are subject to significant anthropogenic impact, as they are unprotected from pollution. Comparison of the data on total dissolved solids (TDS) and anionic composition of groundwater obtained during hydrogeological surveys in the period 1965–1975 and 2009–2013 on three sheets of the hydrogeological map (scale 1:200,000) in different sub-basins of the Dnipro River showed the widespread deep changes in groundwater chemical composition. In addition to a significant anthropogenic pressure, groundwater is significantly affected by climatic factors. Over a forty-year period, TDS in the north of the Dnipro basin increased by 50 %, in the central and southern parts – twice, due to an increase in the content of sulfates and chlorides. Within the analyzed areas in the Middle and Lower Dnipro sub-basins, nitrate pollution of unconfined aquifers is almost widespread. Thus, in a large area, waters of these aquifers are unsuitable for drinking water supply due to the excessive content of chemical elements and compounds of natural and anthropogenic origin. Therefore, one of the priorities of the post-war reconstruction of Ukraine should be the transfer of the rural population to water supply from protected confined aquifers and the improvement of sanitary conditions in rural areas.

Environmental assessment of the quality of surface waters in the upper reaches of the Pripyat basin in Ukraine using different methods


 
 
 
 The aim of the study is to assess the quality of river waters in the upper reaches of the Pripyat River in Ukraine using two methods of environmental assessment of surface water quality in the relevant categories and to identify the effectiveness of these methods. The main factors influencing the water quality of the upper reaches of the Pripyat River in the Volyn region in the absence of large industrial and municipal enterprises in the basin are: the location of quite large rural settlements on the river bank, many of which do not have centralized drainage; the impact of the water of the Turiya River, which is polluted by domestic wastewater in Kovel; development of farms during unsatisfactory condition of the reclamation network; increase of anthropogenic pressure due to construction and plowing of the river. In order to perform ecological assessment of river water quality in the upper reaches of the Pripyat River, the Methodology of Ecological Assessment of Surface Water Quality by Relevant Categories approved in 1998 in Ukraine (Methodology-1998) and the modernized version of this methodology developed in 2012 were used by Ukrainian Research Institute of Environmental Problems (methodology-2012). The second method contains improved evaluation method of water quality according to the criteria of salt composition of water, taking into account the hydrochemical zoning of Ukraine. Analysis of the results obtained by two methods showed that the average annual salt composition (I1) quality of river waters of the upper Pripyat mainly corresponded to the 1st, 4th categories of I, III classes (“excellent”, “satisfactory” by condition, and “very clean”, “slightly contaminated” by the degree of contamination). According to troph-saprobiological (I2) indicators – the 4th category of class III water quality (“satisfactory” by condition and “slightly polluted” by the degree of pollution). According to the indicators of specific substances of toxic water (I3) – the 3rd, 5th category II, III classes of water quality (“good”, “mediocre” by condition and “fairly clean”, “moderately polluted” by the degree of contamination). According to the average annual values of integrated ecological indices (IE), obtained by two methods, the water quality of the upper Pripyat was characterized by the 3rd, 4th categories of II, III classes (“good”, “satisfactory” in condition and “sufficient”, and “clean”, “slightly contaminated” by the degree of contamination). The results of the assessment of the surface water quality of the upper reaches of the Pripyat River by two methods showed that the requirements of the method-2012 are higher to the salt composition of water than in the method-1998. According to this method, water quality was characterized by a worse class (III) compared to the method of 1998, according to which the quality of river waters in the upper reaches of the Pripyat corresponded to class I. Thus, the method-2012 sets stricter requirements for environmental assessment of river water quality, which can make it a more effective mechanism in the field of water protection.
 
 
 

Взаимообусловленность гидрохимических и гидродинамических процессов в эвапоритовых нефтегазоносных бассейнах

The article examines the reasons for the formation of vertical hydrochemical inversion within particular oil and gas basins and points out the role of waters of different genesis in the development of this phenomenon. The following processes of reverse hydrochemical zoning in the sedimentary cover are analyzed: thickening of heavy clay strata and the related squeezing of loosely bound waters, dehydration of clay minerals and catagenic fluid generation accompanying the transformation of organic matter into hydrocarbons of the petroleum series. The hydrochemical inversion at great depths is noted to occur and persist in the environment of the passive hydrodynamic regime; in closed water-drive systems, the demineralization of waters with depth causes the decrease in the hydrodynamic potential gradient, determining the migration pattern not only of water but also of hydrocarbons and, consequently, the location of oil and gas accumulation zones.

Hydrochemical Zoning and Chemical Evolution of the Deep Upper Jurassic Thermal Groundwater Reservoir Using Water Chemical and Environmental Isotope Data

A comprehensive hydrogeological understanding of the deep Upper Jurassic carbonate aquifer, which represents an important geothermal reservoir in the South German Molasse Basin (SGMB), is crucial for improved and sustainable groundwater resource management. Water chemical data and environmental isotope analyses of δD, δ18O and 87Sr/86Sr were obtained from groundwater of 24 deep Upper Jurassic geothermal wells and coupled with a few analyses of noble gases (3He/4He, 40Ar/36Ar) and noble gas infiltration temperatures. Hierarchical cluster analysis revealed three major water types and allowed a hydrochemical zoning of the SGMB, while exploratory factor analyses identified the hydrogeological processes affecting the water chemical composition of the thermal water. Water types 1 and 2 are of Na-[Ca]-HCO3-Cl type, lowly mineralised and have been recharged under meteoric cold climate conditions. Both water types show 87Sr/86Sr signatures, stable water isotopes values and calculated apparent mean residence times, which suggest minor water-rock interaction within a hydraulically active flow system of the Northeastern and Southeastern Central Molasse Basin. This thermal groundwater have been most likely subglacially recharged in the south of the SGMB in close proximity to the Bavarian Alps with a delineated northwards flow direction. Highly mineralised groundwater of water type 3 (Na-Cl-HCO3 and Na-Cl) occurs in the Eastern Central Molasse Basin. In contrast to water types 1 and 2, this water type shows substantial water-rock interaction with terrestrial sediments and increasing 40Ar/36Ar ratios, which may also imply a hydraulic exchange with fossil formation waters of overlying Tertiary sediments.

The Blocking Effect of Clay in Groundwater Systems: A Case Study in an Inland Plain Area.

In order to increase understanding of the hydrogeochemical effects that influence changes in the quality of salt water, we investigated the distribution of saline and fresh water in an inland plain area and, in particular, the scarcity of fresh water resources. Taking the inland plain in Jiyang County as a specific case study, samples of undisturbed clay and underground saline water from different depths were collected to examine hydrogeological changes. A wide variety of methods was used to analyze the blocking effect of clay on the chemical characteristics of the groundwater. These include real-time monitoring for field water quality, tests for isothermal adsorption, a factor analysis model, physiochemical analysis, and correlation analysis. Our results show that the optimal adsorption isotherm of clay for Na+, Ca2+ and Mg2+ in groundwater conform to the established Henry and Langmuir equations for adsorption isotherms. The influence of clay mineral types and content on the blockage of Na+, Ca2+ and Mg2+ in groundwater samples were evident at different depths, with the clay adsorption capacity increasing in line with increases in the clay mineral content. Clay at different depths was found to have the strongest blocking effect on Na+ in groundwater, being systematically greater than its effect on Ca2+ and Mg2+. It is believed that the blocking effect of clay has an important influence on the hydrochemical zoning of groundwater in inland plains and the formation of saline water in groundwater systems. This study therefore provides concrete evidence in support of this supposed effect.

Chemical composition of different types of natural waters in Ukraine

The results of studies of the chemical composition in various types of natural waters of the territory of Ukraine – atmospheric precipitation, surface (river and lake), groundwaters and sea waters are comprehensively summarized and presented for the territory of Ukraine in this paper. The chemical composition of Ukraine's natural waters (rivers, lakes, underground aquifers, seas) is the result of the interaction of a combination of natural factors, as well as their location, mainly in the temperate climatic zone. The average long–term mineralization of atmospheric precipitation is usually in the range of 20–40 mg/l, its chemical composition is predominantly sulfate magnesium–calcium. For the chemical composition of water in the small and medium rivers of Ukraine, hydrochemical zoning is observed in the direction from the northwest to the south-east of the country. Mineralization of river waters also increases in this direction (from 200–300 mg/l to 1,500–3,000 mg/l and more). The composition of the water varies from bicarbonate calcium in the north and west to sodium chloridein the south and southeast. The value of mineralization of lake water varies within very wide limits. There are lakes with very fresh water and low salinity (30 mg/l – small lakes of glacial origin in the Ukrainian Carpathians), and lakes whose water has a mineralization of more than 100 g/l (salt lakes of the Crimea). In the chemical composition of groundwater, the territory of Ukraine mainly exhibits vertical hydrochemical zoning, which manifests itself in the separation of zones of intensive or difficult water exchange. Hydrocarbonate or sulfate waters with a small mineralization (up to 1.0 g/l) are characteristic for the zone of active water exchange. Highly mineralized (50–300 g/l and more) chloride, sodium and chloride-sodiumcalcium waters are common in a zone of hindered water exchange. The ionic composition of the Black Sea water has all the characteristic features of ocean waters but differs from them in relative poverty with ions of chlorine and sodium, the average salinity of the Black Sea waters is 18–19 ‰. In the narrow coastal zone near the mouths of large rivers (the Danube, the Dniester, the Southern Bug, the Dnieper) a decrease in the salinity of the Black Sea waters (up to 5–10 ‰) is observed. The main factors that determine the salinity regime in the Azov Sea (10–13 ‰) are the inflow of saline Black Sea and fresh river (the Don and the Kuban rivers) waters that are mixed in the Azov Sea, as well as the arrival of atmospheric precipitation.

Groundwater Hydrochemical Zoning in Inland Plains and its Genetic Mechanisms

Pore water in inland plain areas, generally having poor water quality, contain complex hydrochemical properties. In order to examine groundwater chemical composition formation characteristics, groundwater in the Jiyang area of Lubei Plain was studied using stratified monitoring of drilling, analysis of water level and water quality, isotope analysis, ion ratio coefficient and isothermal adsorption experiments, hydrochemical characteristics, and analysis of variations in different shallow depths. Results show that: (1) Numerous hydrochemistry types are present in the diving. Along with the direction of groundwater flow, total dissolved solids (TDS) of diving in the study area generally increases and the hydrochemical type changes from the HCO3 type to the HCO3·SO4 type, Cl·HCO3 type and the Cl·SO4 type. (2) Shallow brackish water and freshwater in the horizontal direction are alternately distributed, and shallow brackish water is distributed in the area between old channels, showing sporadic spots or bands, whose hydrochemistry type is predominantly Cl·SO4-Na·Mg·Ca. (3) Affected by the sedimentary environment, hydrodynamic conditions and other factors; diving, middle brackish water and deep freshwater are vertically deposited in the study area. The dynamics of middle brackish water quality are stable due to the sedimentary environment and clay deposits. The hydrochemistry types of middle brackish water are mainly Cl·SO4-Mg·Na and SO4·Cl-Na·Mg, while the deep confined water is dominated by HCO3. (4) The optimal adsorption isotherms of Na+, Ca2+ and Mg2+ in groundwater from clay, with a thickness raging from 6–112 m, conformed to the Henry equation and the Langmuir equation. The retardation of Na+, Ca2+ and Mg2+ in groundwater differed with differing depths of the clay deposit. The trend of change in retardation strength correlates strongly with the TDS of groundwater. Groundwater in the inland plain area is affected by complicated hydrogeochemical processes; in addition, leaching, cation exchange, evaporative concentration and clay retardation have an important influence on the horizontal and vertical zonation of groundwater chemical components.

The characteristics of hydrogeochemical zonation of groundwater in inland plain

To find out the hydrochemical zoning of groundwaterin the inland plain, taking Jiyang plain as an example, based on mathematical statistics, ion ratio coefficient and isotopic analysis method, the characteristics of water chemical composition and its zoning at different depths of 500m were studied. The result shows: ①The groundwater flow system in the study area can be divided into local flow system, intermediate flow system and regional flow system. ②The hydrochemical type of shallow groundwater is complex. The hydrochemical types of middle confined water are mainly Cl⋅SO4—Mg⋅Na and SO4⋅Cl—Na⋅Mg. The deep confined water is mainly HCO3. ③The TDS of shallow groundwater increases gradually along the direction of groundwater flow. ④The shallow saltwater and freshwater are alternately distributed in horizontal direction, and saltwater is distributed sporadically in the interfluve area with sporadic punctate or banded, and hydrochemical types are mainly Cl⋅SO4—Na⋅Mg⋅Ca. Conclusion: Groundwater in the study area is affected by complicated hydrogeochemical action, mainly in the form of filtration, cation exchange and evaporation. The inland plain area is characterized by hydrogeochemical zonation in horizontal and vertical.

The Hydrochemical zoning of groundwaters in the mesozoic deposits of the north-eastern part of the Karakum water drive system (the Bukhara-Khiva Oil-and-Gas-Bearing Region)

The Hydrochemical zoning of groundwaters in the mesozoic deposits of the north-eastern part of the Karakum water drive system (the Bukhara-Khiva Oil-and-Gas-Bearing Region)

Study on the hydrochemical characteristics of groundwater along the Taklimakan Desert Highway

Groundwater is the only water source of the shelterbelt along the Taklimakan Desert Highway in northwestern China. Understanding the hydrochemical zoning characteristics, material source, and hydrochemical processes of this desert groundwater is important for rational groundwater exploitation. Meanwhile, determining the location of the dividing boundary, which divides the influence ranges of the Tarim river and the Kunlun mountain river system on the desert groundwater, is meaningful for the local desert hydrogeological study. For these objectives, 105 groundwater samples were investigated to obtain analytical data of groundwater chemistry, and ionic relations methods including ratio graphs and Gibbs plots were applied in the chemical analysis for these data. Chemical analysis shows that desert groundwater is characterized by Cl·SO4–Na·Mg and Cl−·SO4–Na types with total dissolved solid (TDS) of 2.80–29.77 g/L. Spatial variation patterns of major ions, TDS, and SO42−/Cl− molar ratio reveal clear four hydrochemical zones along the groundwater flow direction on one hand; on the other hand, these variation patterns also indicate that the boundary dividing the influence ranges of the Tarim river and the Kunlun mountain river system is the approximate location of Well 030. Ratio graphs show that the average molar ratios (Na+ + K+)/Cl− (1.05) and (Ca2+ + Mg2+)/SO42− (0.93) are approximately equal to 1, and there is an approximately linear correlation between (Na+ + K+) and SO42−. These results reveal that the groundwater composition is mainly influenced by dissolution of evaporate (halite, gypsum, and mirabilite). Moreover, ionic relations demonstrate that the dominating hydrochemical processes in the groundwater evolution are evaporation and cations exchange.

Hydrochemical zoning: natural and anthropogenic origins of the major elements in the surface water of Taizi River Basin, Northeast China

Discriminating the hydrochemical origins in the polluted rivers is a challenge work due to multiple sources contributing to the river’s chemical composition. The Taizi River, as an important tributary of the Liao River, in Northeast China, is flowing through an urban-, industry-, and agriculture-intensive area, and its hydrochemistry has been disturbed by human activities especially in the lower basin. In this study, an extensive analysis has been conducted to evaluate the natural and anthropogenic origins of the hydrochemistry in the Taizi River Basin. Three hydrochemical zones are determined based on hydrological connectivity, land use types and lithology, and the hydrochemistry pattern has changed from Ca-HCO3 type to Ca-HCO3-SO4 type from the upper basin to the lower basin due to increasing areas of agriculture and residence land. Six end members including the rain inputs, sewage discharge, mine drainage, carbonate, silicate and evaporate weathering are discriminated in the study area by applying a two stage stoichiometric method. The first stage is used to separate the anthropogenic inputs (sewage discharge and mine drainage) by an inversion technique, and the second stage is evaluating the rock weathering contributions from carbonates, silicates and evaporates by a forward method. Chemical budget calculation shows that carbonate weathering and anthropogenic inputs are two important factors controlling the hydrochemistry with contributions of about 52 and 27 % of the TDS, respectively. In addition, the contribution of anthropogenic inputs increases from 20 % in the upper basin to 30 % in the lower basin.

Hydrochemical zoning of valley peatlands as a result of water supply conditions - examples from Poland.

The chemical composition of water from two peatlands was investigated. Both peatlands, which are nature reserves, are located in central Poland in the Widawka and Rawka River valleys. The study concerned groundwaters, peat waters from different depths, and waters from draining ditches. The research permitted determination of the hydrochemical zoning of the peatlands resulting from the complex character of the water supply. The hydrochemical interpretation of surface waters outflowing alongside the ditches, in terms of their similarity to particular zones, provides an insight into the water-feeding structure of the peatlands. In the evaluation, hydrochemical indicators were applied, which have been used in hydrogeological studies. They are based on equivalent concentrations of the major ions: sodium, calcium, chlorides, and sulphates, selected from other hydrochemical elements by means of principal component analysis (PCA), conducted individually for each peatland. The analyses showed a high contribution of unconfined and confined groundwaters to the water supply, with clearly distinguishable zones, in terms of their transit through the structures of the peatlands.

HYDROCHEMISTRY OF THE MOUNTAIN RIVERS WITH FOREST-GRASSLAND TYPES OF THE VERTICAL ZONING

The article analyzes the spatial-temporal characteristics of dissolved organic matter (DOM), pH, and salinity (∑m) natural river water of provinces and countries of mountains with forest-grassland types of the vertical zoning of the CIS. The work is based on the results of many years experimental studies and observations in the network of hydrometeorological service. The reaction of river water of forest-meadow mountains during the year is neutral and slightly alkaline, in a few provinces it is weak-acid and alkaline, and in the Amur-Primorye country it is slightly acidic and neutral. The salinity of the water changes dramatically from very low in the Amur-Primorye country, Pribaikalia and Transbaikalia (40–100 mg/ dm 3 ), small in the Alpine-Carpathian country and in the Altai-Sayan mountains (120–200 mg/dm 3 ) to the average values (200–400 mg/dm 3 ) on the rest of the territory. The color of river water varies from small (15–20°) in the mountains of Western and Central Asian types of zoning to average values (30–45 o ) in the mountains of Central and Far Eastern types of zoning. The magnitude of the permanganate oxidizability of water ranges from small (4–5 mg/dm 3 ) to the average (7–8 mg/dm3 ), the bichromate oxidizability has mostly average values (14–20 mg/dm 3 ); for forest-meadow mountains of the CIS they are equal to 7 and 18 mg/dm3 , PO/BO – 41%, DOM/∑m – 10%. Extreme average concentrations of humic (HA) and fulvic (FA) acids in the water of the rivers of forest-meadow mountains vary from 0.005–0.035 in winter and 0.015–0.055 in summer low-water periods up to 0.090–0.230 mg/dm 3 of carbon in high water, FA – respectively from 0.150–0.350 and 0.460–0.620 to 0.930–1.29 mg/dm 3 . Hydrochemical zoning of river water is developed very well in mountains with forest-grassland types of vertical zoning with optimally formed geomorphological and landscape storeyed structure.

The role of vertical migration of high-temperature fluids in the genesis of formation waters in oil-gas fields in the north of the Western Siberian basin

All northern areas of Western Siberia exhibit a discontinuity in the normal vertical hydrochemical zoning and formation of an inversion hydrochemcial profile characterized by total mineralization of formation waters that decrease with depth and by the discovery of waters with mineralization levels of 1–7 g/L and less, as well as a simultaneous “inconsistent” change in the chemical composition of formation waters with Cl-Na-Ca to HCO3-Cl-Na deeper than 2–3 km and simultaneous “irregular’ change in the chemical composition of formation waters with Cl-Na-Ca to HCO3-Cl-Na. Based on the use of the B/Br ratio and a Na-K geothermometer, a conclusion is made that the formation of slightly ( 150°C) fluids saturated with CO2 into water-bearing rocks. This indicates the formation of deposits of hydrocarbons that are found in the regions of inversion waters as result of the upward vertical, but not lateral formation migration of a water-oil mixture.

Morphometric Trait Variation in Thalassia testudinum (Banks ex Konig) Associated to Environmental Heterogeneity in a Subtropical Ecosystem

In order to advance on the understanding of the morphology plasticity of Thalassia testudinum at different hydrochemical conditions, the size–frequency distributions of shoot- specific and area-specific characteristics were investigated in five hydrochemical regions of Bahia de la Ascension, a non-disturbed coastal bay in the Mexican Caribbean region. At Bahia de la Ascension was observed that the size-frequency distributions of the morphometric characteristic of Thalassia testudinum were registered in the lowest modal classes, the only exception was the maximum leaf length. All the morphometric variables analyzed showed differences among hydrochemical regions, indicating the plasticity of this seagrass according to site-specific water quality conditions, suggesting its utility as ecoindicator, and confirm the hydrochemical zoning of Bahia de la Ascension. The results of the multivariate analysis used to establish the association among the hydrochemical regions and the morphometric trait variation of Thalassia testudinum indicate that the best shoot-specific and area-specific characteristics were registered in environmentally stable areas across time and with relatively high nutrient concentrations, high transparency and salinity ranging from 25 to 35, which demonstrate the sensitivity of size–frequency distributions characteristics to environmental variability, indicating that T. testudinum morphology responds strongly to local and regional hydrochemical heterogeneity.

Hydrochemical zoning studies in assessment of geoecological safety of near-surface radioactive waste repositories

Geological, hydrogeological, and climatic conditions in the region of the Sergiev Posad radioactive waste disposal site, as well as the design of repositories, are analyzed. Organization of the geomonitoring of the territory is considered.

Hydrochemistry of Salt Lakes of the Qinghai-Tibet Plateau, China

The authors have carried out scientific investigations of salt lakes on the Qinghai-Tibet Plateau since 1956 and collected 550 hydrochemical data from various types of salt lakes. On that basis, combined with the tectonic characteristics of the plateau, the hydrochemical characteristics of the salt lakes of the plateau are discussed. The salinity of the lakes of the plateau is closely related to the natural environment of lake evolution, especially the climatic conditions. According to the available data and interpretation of satellite images, the salinity of the lakes of the plateau has a general trend of decreasing from north and northwest to south and southeast, broadly showing synchronous variations with the annual precipitation and aridity (annual evaporation/annual precipitation) of the modern plateau. The pH values of the plateau salt lakes are related to both hydrochemical types and salinities of the lake waters, i.e., the pH values tend to decrease from the carbonate type → sodium sulfate subtype → magnesium sulfate subtype → chloride type; on the other hand, a negative correlation is observed between the pH and salinities of the lakes. Geoscientists and biological limnologists generally use main ions in salt lakes as the basis for the hydrochemical classification of salt lakes. The common ions in salt lakes are Ca2+, Mg2+, Na+, K+, Cl− SO42−, CO32−, and HCO3−. In this paper, the Kurnakov-Valyashko classification is used to divide the salt lakes into the chloride type, magnesium sulfate subtype, sodium sulfate subtype and carbonate type, and then according to different total alkalinities (KC = Na2CO3 + NaHCO3/total salt × 100%) and different saline mineral assemblages, the carbonate type is further divided into three subtypes, namely, strong carbonate subtype, moderate carbonate subtype and weak carbonate subtypes. According to the aforesaid hydrochemical classifications, a complete and meticulous hydrochemical classification of the salt lakes of the plateau has been made and then a clear understanding of the characteristics of N–S hydrochemical zoning and E-W hydrochemical differentiation has been obtained. The plateau is divided into four zones and one area. There is a genetic association between certain saline minerals and specific salt lake hydrochemical types: the representative mineral assemblages of the carbonate type of salt lake is borax (tincalconite) and borax-zabuyelite (L2CO3) and alkali carbonate-mirabilite; the representative mineral assemblages of the sodium sulfate subtype are mirabilite (thenardite)-halite and magnesium borate (kurnakovite, inderite etc.)-ulexite-mirabilite; the representative mineral assemblages of the magnesium sulfate subtype are magnesium sulfate (epsomite, bloedite)-halite, magnesium borate-mirabilite, and mirabilite-schoenite-halite, as well as large amount of gypsum; The representative mineral assemblages of the chloride type are carnallite-bischofite-halite and carnallite-halite, with antarcticite in a few individual salt lakes. The above-mentioned salt lake mineral assemblages of various types on the plateau have features of cold-phase assemblages. Mirabilite and its associated cold-phase saline minerals are important indicators for the study of paleoclimate changes of the plateau. A total of 59 elements have been detected in lake waters of the plateau now, of which the concentrations of Na, K, Mg, Ca, and Cl, and SO42−, CO32−, and HCO3− ions are highest, but, compared with the hydrochemical compositions of other salt lake regions, the plateau salt lakes, especially those in the southern Qiangtang carbonate type subzone (I2), contain high concentrations of Li, B, K, Cs, and Rb, and there are also As, U, Th, Br, Sr, and Nd positive anomalies in some lakes. In the plateau lake waters, B is intimately associated with Li, Cs, K and Rb and its concentration shows a general positive correlation with increasing salinity of the lake waters. The highest positive anomalies of B, Li, Cs, and K center on the Ngangla Ringco Lake area in the western segment of the southern Qiangtang carbonate type subzone (I2) and coincide with Miocene volcanic-sedimentary rocks and high-value areas of B, Li, and Cs of the plateau. This strongly demonstrates that special elements such as B, Li, and Cs on the plateau were related to deep sources. Based on recent voluminous geophysical study and geochemical study of volcanic rocks, their origin had close genetic relation to anatectic magmatism resulting from India–Eurasia continent–continent collision, and B–Li (-Ce) salt lakes in the Cordillera Plateau of South America just originated on active continental margins, both of which indicate that global specific tectonically active belts are the main cause for the high abundances of B, Li, and Cs (K and Rb) in natural water and mineralization of these elements.

Movement characteristics of Karst water in a deep mining area

In order to study the movement characteristics of groundwater in a deep mining area and solve the dispute of the distribution rule of hydro-chemical zoning which is contradicted by lixiviation water zoning in a horizontal direction, we directed our attention to the source of deep groundwater, its seepage and hydro-chemical characteristics in a typical mining area. We used a neotectonic water-control theory, chemical and isotope methods, as well as a method for analyzing dynamic groundwater conditions. The results indicate that 1) Karst water in the deep and medium parts of this mining area is recharged by vertical leakage through neotectonic fractures rather than seepage along strata from subcrop parts or surrounding flows; 2) from surface to deep leakage paths, the variation in the types of chemical groundwater agrees with the normal lixiviation water distribution rule and the age of mixed groundwater increases; 3) the water-rich zones along neotectonic fractures correspond with water-diluted zones in a horizontal direction; 4) the leakage coefficient and water capacity of aquifers increases during the flow process of Karst water along the antidip direction (from west to east) and 5) Karst water in shallow mining areas forms a strong runoff belt along strikes and quickly dilutes the water from deep and medium mining areas. Overall, chemical and dynamic water characteristics actually agree with in terms of the entire consideration for differences in vertical leakage and abnormalities in the zone of water chemical distribution, along a horizontal runoff direction.

Identification of hydrogeochemical zones in postglacial buried valley aquifer (Wielkopolska Buried Valley aquifer, Poland)

This article presents the difficulty in identifying the hydrochemical zoning of a semi-confined aquifer, characterised by a relative small spatial differentiation of groundwater chemistry. It is shown that multivariate statistical methods can be used for the recognition and interpretation of the groundwater chemistry distribution in an aquifer. The hydrochemical zonation caused by both natural and anthropogenic processes was identified using factor analyses in combination with a classical interpretation of the hydrogeological material. The interpretation of the groundwater chemistry allows both identification of the aquifer recharge mechanism and verification of the groundwater-flow system.

Hydrogeochemical effects of groundwater mining of the Sierra de Crevillente Aquifer (Alicante, Spain)

The groundwater mining of the Crevillente aquifer (southeastern Spain) has resulted in the progressive deterioration of water quality, with particularly significant increases in chloride, sulfate, and sodium. The possibility of a vertical hydrochemical zoning is deduced that would require examining the importance of the geometry and lithology (evaporitic materials) in the salinization process. The time of water-rock contact (residence time) and dilution by infiltration of rainwater also influences the hydrogeochemistry of the aquifer. The hydrochemical data are useful in defining the conceptual model of the aquifer, completely karstified with relative homogeneity.