As explained by Galina Borodulina, hydrogeologist and Senior Researcher at NWPI KarRC RAS, iron-rich water occurs in many places, even with iron concentrations far higher than in the martial waters. However, in the vast majority of cases, high-iron water is also highly mineralized and very acidic. Such water is undrinkable.
– A distinctive feature of martial waters is that their iron concentration is extremely high for fresh water –up to 100 mg per liter! At the same time, they have a favorable acid-base index, pH 6–6.5. With doctor’s prescription, they can be used for health purposes without prior water treatment. No other deposit in our country can boast such a happy combination of high iron concentration, low total dissolved solids, and a favorable pH, – emphasized Galina Borodulina.
Galina Borodulina, Senior Researcher, Northern Water Problems Institute KarRC RAS
Due to their therapeutic properties, the martial waters are included in the classifications of mineral waters and the State Standard (GOST) "Potable Natural Mineral Waters" under their own hydrochemical type name – ‘martial’.
Martial waters in Karelia have been studied since the late 18th century, but at a modern level – since the mid-20th century, when the health resort was being organized. The most detailed observations have been conducted by researchers from the Laboratory of Hydrochemistry and Hydrogeology NWPI KarRC RAS: in 2018 specialists launched a monitoring program that includes regular, detailed chemical analytics of the water. During these eight years, water samples have been taken from the wells at least once a month. The analyses are carried out in the laboratories of the Karelian Research Centre RAS, the Science Park of St. Petersburg State University, and the Federal Research Centre for Integrated Arctic Studies of the RAS Ural Branch.
Scientists regularly take water samples for thorough chemical analytics
The collected data series provide grounds for inferring the formation process of the martial waters. This knowledge is essential for understanding the current situation and predicting the springs’ future. The results of the study were published in 2025 in the Vestnik of Saint Petersburg University journal.
– A common belief is that groundwater rises from somewhere deep underground. This is not always the case. The martial waters form inside loose glaciolacustrine sediments and in the ancient weathering crust of pyritized shungite schists at a shallow depth of 5-10 m around the boreholes. The recharge area of the aquifer lies on the watershed between the Shuya and Suna rivers, near Lake Verkhneye Lampi – on an upland about two km away from the tube wells in the Gabozero valley. Recharge occurs through precipitation percolating through the shungite-bearing rocks, – said Galina Borodulina.
Senior Research of Hydrochemistry and Hydrogeology Laboratory NWPI KarRC RAS Galina Borodulina and Chief Hydrogeologist of the same laboratory Galina Chesalina
Shungite-bearing rocks contain sulfides – mainly pyrite (FeS₂). Coming in contact with oxygen-saturated precipitation, pyrite is actively oxidized, with ferrous iron and sulfuric acid formed as a result. As the acid is neutralized through interaction with the rocks, sulfates and iron hydroxides are precipitated and pH rises.
The factor that helps ferrous iron – the main balneological component of the mineral water – remain dissolved is the anoxic environment formed under a layer of clay as the groundwater moves from the recharge area toward the valley.
When water flows spontaneously out of the boreholes, it comes into contact with oxygen, and the iron begins to oxidize rapidly, precipitating as ochre-colored sediment. This is why martial water cannot be stored to be consumed later.
Coming in contact with oxygen, iron in water is rapidly oxidized, forming ochre-colored precipitate
As the scientists note, the time most conducive to sulfide oxidation was immediately after the glacier retreated from this area, around 13,000 years ago, during a cold climate epoch. There was very little liquid water, mainly present as thin films. It was under these conditions that water-soluble sulfates began to appear and accumulate. There being no rainfall, they were not leached away but built up. When rains began and the aquifer formed, precipitation started to leach the stored sulfates out, and the martial water making ‘machine’ has been operating ever since. This mechanism was first hypothesized back in the 1930s and now scientists have confirmed it using modern methods.
– The formation of martial waters was made possible by a lucky combination of quite a few factors – the composition of the rocks, the landscape, and the geological history. We can confidently say that this deposit is unique, – notes Galina Borodulina.
However, studies have shown that the reserves of relict waters are now nearly depleted: where their isotopic composition in the late 1980s was characteristic of glacial meltwater, it has now changed to be similar to that of modern atmospheric precipitation. Yet, the chemical composition of the water has generally remained the same.
Mean daily air temperature, precipitation, and static water table depth in wells #1-4 of the Martial Waters deposit
Atmospheric recharge with a rise in the aquifer’s water table, especially during the spring high-water period, leads to increased water discharge through boreholes and higher mineralization. At the same time, the long-term trend is for a decrease in overall mineralization, i.e. the content of dissolved chemical elements in the water is declining. Whether this is due to environmental and climate changes or to anthropogenic impact scientists still need to clarify, but one thing is for sure: this unique deposit must be treated with special care.
The deposit is surrounded by a three-tier buffer zone with heavy restrictions on human activities
– Breaching an aquifer is easy, but eliminating the consequences is very difficult. The deposit is surrounded by a three-tier buffer zone with strict limitation of human activity, e.g. earthworks, the construction of water conduits, and so on. There must be no waste dumping, landfilling, or any littering and pollution in the area, because whatever percolates down the ground ends up in the water source. However, with the health resort, a village, and a road within the water protection zones, meeting these requirements is problematic. No wonder that when the health resort was only being planned in the early 1930s, the renowned balneologist Adolf Bickel recommended siting it on the eastern side of the Gabozero valley in order to preserve the deposit in its natural state, – emphasizes Galina Borodulina.
Ultimately, the deposit must be monitored and conserved relying on a scientific approach, on a continuous basis.
