Vol 103

The chemistry of groundwater at the bottom of the World Ocean differs sharply from the chemistry of groundwater on the continents. It is determined by the complex interaction of ocean waters, sediments deposited on the bottom, and biogeochemical and other processes.

Data on the age and thickness of sediments that compose the sedimentary cover of artesian basins (ABs) of mountainous folded regions can determine how much of the thickness of the sedimentary cover is occupied by freshwater.

Zonality is a planetary property of groundwater that determines the shape of its spatial and temporal arrangement in the Earth's interior. This definition requires clarification of the physics of our ideas about zonality.

In the relief of the modern surface of Prionezhye three terraces with absolute marks of hypsometric levels 30-60, 60-100 and 100 m and more are traced. The maximum heights do not exceed 300 m.

New data on hydrochemical zonality of the upper hydrogeological floor of the northern part of the Onego-Dvinsky interfluve, obtained as a result of surveying and prospecting for water in recent years, allowed to carry out hydrochemical zoning, territory, identify the main features of the chemical composition of groundwater and consider the processes of their formation.

Involvement of mathematical methods is increasingly used in hydrogeochemistry. The most widespread is mathematical statistics, which is used to solve a variety of problems, in particular, to determine the strength and nature of the relationship between the features, as well as the degree of influence of individual factors in the formation of the chemical composition of waters.

Studies in recent years show that organic matter plays a significant role in the formation of the chemical composition of groundwater. Let us consider this question on the example of the known ferruginous waters of the North-Dvinsky depression, made by glacial, interglacial and marine Quaternary sediments.

The taiga region, in which the features of water migration of gold and other ore elements were studied, is characterized by flat, weakly articulated relief, deep seasonal freezing of soil-cover deposits and wide development of upper bogs.

One of the most important factors in the formation of the chemical composition of groundwater is high temperature, the influence of which affects the intensity of dissolution and hydrolysis of minerals, and cation exchange.

At present, in the special hydrogeological literature much attention is paid to the problem of studying the impact of technogenesis on the quality of groundwater. In the development of these studies, the article gives a consistent analysis of the conditions of formation of hydrogeochemical zonality in the groundwater flow within the halo distribution of technogenic solutions of potash production.

One of the main reasons for changes in the chemical composition of groundwater during drainage of developed deposits is the intensification of the overflow of pressure, more mineralized water of deep horizons, or squeezing (due to the growth of intra-class stresses) pore water from weakly permeable layers and blocks with a general decrease in head in the upper aquifers.

The artesian basins of the intermountain plains of the western Tell-Atlas (North-Tlemsen, Bel-Abbes, Telaga and Maskara) are located in the northwestern part of Algeria and are characterized by relatively favorable orohydrographic and climatic parameters and hydrogeological conditions.

Geographical and geological sketch of Northern Algeria. The Algerian folded region is bounded on the south by the Saharan Atlas and on the north by the coastal flexure; four zones are distinguished here: the Kabylian, Tall Aglas, High Plateau and Saharan Atlas.

The concentration of hydroxyl ion in natural waters is one of the main parameters governing most natural hydrogeochemical systems; therefore, there is a natural interest in ultraalkaline waters, in which the pH reaches a maximum.

Prior to the exploitation of the Leningrad oil shale deposit, the piezometric surface of the aquifers was gently declining in a north-west direction - the total groundwater flow was directed towards the Gulf of Finland, the fluctuations of the flow by seasons were determined by hydrometeorological conditions.

Sufficient clarity in understanding the general geological and geochemical picture of lateritic weathering crusts formation, at the same time, urgently requires further studies to investigate the possible mechanism of nickel accumulation in weathering mountain zones and to clarify the role played by groundwater.

An obligatory stage of hydrogeochemical sampling data processing is the systematization of observations. Systematization is carried out in order to identify homogeneous hydrochemical fields, determine the background and anomalous content of components, which allows to establish the commonality of the conditions of formation of the composition of the sampled water.