Hydrogeochemistry of the permafrost zone in the central part of the Yakutian diamond-bearing province,Russia

The hydrogeochemical characteristics and zonation of the permafrost zone in the central part of the Yakutian diamond-bearing province formed mainly under the influence of cryogenic processes that occurred in the late Cenozoic. On the basis of field and experimental studies, conclusions were formulated that the perennial cryogenesis of the sedimentary cover in this region resulted in increasing the concentration of carbonate and sulfate compounds in groundwaters as well as increasing the concentration of easily soluble compounds (sodium, magnesium, and calcium chlorides).

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Resumen Las características hidrogeoquímicas y la zonación del permafrost existente en el centro de la provincia de Yakutia, rica en diamantes, se formaron fundamentalmente bajo la influencia de procesos criogénicos durante el tramo final del Cenozoico. Con base en estudios de campo y experimentales, se ha concluido que la criogénesis perenne de la cubierta sedimentaria de la región ha provocado un aumento de la concentración de compuestos de carbonato y sulfato en las aguas subterráneas, además de incrementar la concentración de compuestos solubles, como el sodio, magnesio y cloruros de calcio.

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Résumé Les caractéristiques hydrogéochimiques et la zonation de la région de permafrost dans la partie centrale de la province diamantifère de Yakoutie ont été acquises principalement sous l'influence des processus cryogéniques qui existent depuis la fin du Tertiaire. Sur la base d'études expérimentales et de terrain, on conclut que la cryogenèse permanente de la couverture sédimentaire de cette région a provoqué un accroissement de la concentration des composés carbonatés et sulfatés dans les eaux souterraines, en même temps que celui de composés facilement solubles, comme les chlorures de sodium, de magnésium et de calcium.

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Statistical aspects of eliminating systematic effects

Summary A procedure for processing measurements subject to systematic effects is derived such that it ensures their optimum elimination in the results of the processing. It is proved that no other method of eliminating systematic effects yields better results.

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The use of the discrete surface fourier analysis of anomalous fields for resolving them

Summary The subject of this paper is one method of numerical computing of the resolution of a summary anomalous field into its components, a method which respects the spectral approach to this problem.Dedicated to 90th Birthday of Professor Frantiek Fiala     

Prediction of land subsidence caused by groundwater exploitation in Hanoi, Vietnam, using multifactorial correlation analysis

Multifactorial correlation analysis is a new method used to predict the land subsidence caused by groundwater exploitation. This article introduces and applies the method to establish the function of t...     

Dolomite-calcite textures in early carbonatites of the Kovdor ore deposit,Kola peninsula,Russia: their genesis and application for calcite-dolomite geothermometry

In early calcite carbonatites of the Kovdor ore deposit four morphological types of dolomite are represented. In the first type, dolomite microcrystals occur as lamellae enclosed by optically continuous calcite. In the second, dolomite microcrystals occur as segmented rods, plates and xenomorphic grains, enclosed by optically discontinuous calcite, and in the third, dolomite is represented by grains of various morphologies, situated along calcite grain boundaries. The fourth type of dolomite occurs as a fine-grained aggregate, which develops along grain boundaries and cleavage cracks of calcite. From microscopic, scanning electron microscope and microprobe studies of these different types of dolomite microcrystals, as well as the calcite associated with them, it can be concluded that the first type of dolomite was exsolved from magnesian calcite during cooling. The second, and the third types of dolomite microcrystals were formed by recrystallization. The fourth type of dolomite was formed by metasomatic dolomitization. As the result of these two processes-recrystallization and metasomatic dolomitization-early dolomite microcrystals seldom occur. The composition of the early-formed primary magnesian calcite yielded temperatures of exsolution of dolomite from magnesian calcite between 665 and 700°C.     

Soil quality indicator of oxisols grown with sugarcane and native forest in northeastern São Paulo state,Brazil

The evaluation of soil quality is an important tool for degradation monitoring and sustainable management implementation. The objective of this study was to measure physical and chemical soil properties to set soil quality and validate a model of soil quality indicator in latosols (oxisols) under sugarcane cropping and native forest. The study was carried out in the cities of Araras, Santa Ernestina, and Guariba in São Paulo State, Brazil. We collected 24 samples of disturbed and undisturbed soil at 0.0–0.10 m layer from three areas grown with sugarcane and neighboring locations under native woodland. We assessed the following soil properties: (a) chemical—pH in CaCl₂, organic matter (OM), phosphorus (P), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), potential acidity (H?+?Al), aluminum (Al³⁺), and sulfur (S); (b) physical—macro- and microporosity, soil bulk density (Ds), aggregate stability, mean weight diameter (MWD), rill (K_r) and interrill (K_i) global erodibility, shear stress (τc), and magnetic susceptibility (MS). Data underwent multivariate statistics to identify the properties that denote soil quality and to set their weights within the functions of soil quality indicator (SQI). This study showed that the multivariate analysis was efficient in determining which physical and chemical properties were most sensitive, of which we can mention total sand, MS, clay, microporosity, Mg, Ca, pH, and OM. We can therefore conclude that the quality indicators of soils grown with sugarcane were lower than those under forest were, showing the need for adoption of conservation management practices.     

Microbial processes and factors controlling their activities in alkaline lakes of the Mongolian plateau

A striking feature of the Mongolian plateau is the wide range of air temperatures during a year,-30 to 30°C.High summer temperatures,atmospheric weathering and the arid climate lead to formation of numerous alkaline soda lakes that are covered by ice during 6–7 months per year.During the study period,the lakes had p H values between 8.1 to 10.4 and salinity between 1.8 and 360 g/L.According to chemical composition,the lakes belong to sodium carbonate,sodium chloride-carbonate and sodium sulfate-carbonate types.This paper presents the data on the water chemical composition,results of the determination of the rates of microbial processes in microbial mats and sediments in the lakes studied,and the results of a Principal Component Analysis of environmental variables and microbial activity data.Temperature was the most important factor that influenced both chemical composition and microbial activity.p H and salinity are also important factors for the microbial processes.Dark CO 2 fixation is impacted mostly by salinity and the chemical composition of the lake water.Total photosynthesis and sulfate-reduction are impacted mostly by p H.Photosynthesis is the dominant process of primary production,but the highest rate(386 mg C/(L?d)) determined in the lakes studied were 2–3 times lower than in microbial mats of lakes located in tropical zones.This can be explained by the relatively short warm period that lasts only 3–4 months per year.The highest measured rate of dark CO 2 assimilation(59.8 mg C/(L?d)) was much lower than photosynthesis.The highest rate of sulfate reduction was 60 mg S/(L?d),while that of methanogenesis was 75.6 μLСН 4 /(L?d) in the alkaline lakes of Mongolian plateau.The rate of organic matter consumption during sulfate reduction was 3–4 orders of magnitude higher than that associated with methanogenesis.