Groundwater pollution in the Mesta River terrace caused by Eleshnitsa tailings pond – current status

Even after the implementation of eco-protective measures, the Eleshnitsa tailings pond continues to contaminate the Quaternary aquifer, formed in the alluvial deposits of Mesta River. A three-dimensional model of mass transport of selected key pollutants is developed on the basis of hydrochemical studies, geophysical surveys, and processing and systematization of monitoring data. The spread and degree of contamination in the Quaternary aquifer are estimated.

Hydrogeochemical Evolution of an Aquifer Regulated by Pyrite Oxidation and Organic Sediments

Detailed full-scale groundwater monitoring was carried out over a period of nine years, sampling at selected points along the groundwater flow direction in its final stretch. This established the hydrogeochemical evolution along the flow of a natural system formed by a calcareous aquifer which discharges and then passes through a quaternary aquifer of lake origin which is rich in organic matter. This evolution is highly conditioned by the oxidation of pyrites that are abundant in both aquifers. In the first aquifer, one kilometre before the discharge location, oxidizing groundwater crosses a pyrite mineralization zone whose oxidation produces an important increase in sulphates and water denitrification over a short period of time. In the quaternary aquifer with peat sediments and pyrites, water experiences, over a small 500 m passage and residence time of between three and nine years, a complete reduction by way of pyrite oxidation, and a consequent increase in sulphates and the generation of hydrogen sulphuric acid. This is an example of an exceptional natural hydrogeological environment which provides guidance on hydrogeochemical processes such as denitrification.

HYDROGEOLOGICAL FEATURES OF THE DEVELOPMENT OF THE BOROK QUARRY (NOVOSIBIRSK)

The hydrogeological features of the development of the Borok granite quarry, the oldest in Siberia, are considered in the article. It was found that the hydrogeological conditions of the quarry are quite difficult. Two aquifers: alluvial deposits of the Quaternary age and Paleozoic granites were identified according to the geological structure of the quarry, assessing the main hydrogeochemical indicators of the drainage waters of the quarry. The volume of water inflows for the last 70 years has been analyzed. The role of fissure-vein waters of Paleozoic granites, Quaternary aquifer and atmospheric precipitation during the year is substantiated.