Hydrogeology

Kotelnikovsky Spring - Khakussy Spring - Dawsha spring - Snake spring - Goryaschinsk Spring - Arshan - Nilowa Pustyn - Zemchug

Zemchug 1 (1954)

The first borehole was drilled in unconsolidated Caenozoic rocks in 1954. It has a depth of 1026 m. The thermal water of temperatures between 38–39 °C has a high content of silica acid and methane. The general components are hydrocarbonate and sodium. The thermal water is an artesian with an outflow of about 8 L/s. The mineralwater is formed in 780–860 m depth and has a total mineralization of about 1.2 g/L.

Table: hydrogeochemical parameters
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date 2004-08-05
time 3:45 pm
pH = 8.1
conductivity = 1450 µS/cm
temperature = 37.5 °C
E_H = -6 mV
O₂ = 0.92 mg/L = 15.10 %

Fe(tot) = 0.40 mg/L
Fe²⁺ = 0.01 mg/L
NO₃^- = 1.90 mg/L
NO₂^- = 0.011 mg/L
PO₄^3- = 2.33 mg/L

The thermal water has a basic character because of the high pH of 8.1. The oxygen saturation is very low like all other sampled thermal springs. Thus the redox potential is negative near the value 0 and describes the transition zone between partly and completely reduced conditions. The electrical conductivity is relatively high. The estimation of the mineralization on the base of the electrical conductivity multiplied with the factor 0.725 results in a total of about 1.1 g/L which supports the data above.
The content of iron, nitrate and phosphate is high in comparison to the other samples of the area of Arshan but considering the other thermal waters the measured values are similar within the same dimension.

Zemchug 2 (1987)

In 1987 a second borehole was drilled. With 1000 m depth it is not as deep as the first one but the thermal water has a higher temperature up to 51.5 °C. The exact temperature depends on the depth from which the water comes. The general components here are hydrocarbonate, chloride, magnesium and calcium. Besides, it has a high concentration of carbonate acid.
The water can have up to 10 mg/L iron and in addition to that it has also some proportions of radon. The total mineralization should be about 4.9 g/L. The thermal water is used for the treatment of skin diseases and nervous diseases.

[Borehole of Zemchug (1987)]

Table: hydrogeochemical parameters
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date 2004-08-05
time 4:00 pm
pH = 7.1
conductivity = 6090 µS/cm
temperature = 45.1 °C
E_H = 161 mV
O₂ = 2.5 mg/L = 47.7 %

Fe(tot) = 0.64 mg/L
Fe²⁺ = 0.00 mg/L
NO₃^- = 3.80 mg/L (1:1 diluted)
NO₂^- = 0.00 mg/L
PO₄^3- = 1.20 mg/L (bubble formation)

The water of the younger and shallower borehole has also a basic character but the pH is 1.0 pH units lower than the pH of the older borehole. The remaining parameters like temperature, electrical conductivity, redoxpotential and oxygen saturation are higher.

[Comparison of the water samples taken of Zemchug (1)]

The positive redox potential and therefore the oxidized conditions are due to the increased oxygen supply. The immense rise of the electrical conductivity reflects a very high total mineralization. According to the rule of thumb 6090 µS/cm [*0,725] is about 4.4 g/L mineralization which is very high.
The content of iron and nitrate is also higher but it should be noticed that the value of nitrate is the result of a 1:1 dilution. Besides, the value of phosphate can be incorrect because of the annotation “bubble formation” caused by the disturbance of other existing elements or species influencing the photometric measurements [see interferences].

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