Mineral composition is determined by the total content of the seven major ions: K +, Na +, + Ca2, Mg2 +, SO42-, HCO3-. The main sources are increasing salinity groundwater and wastewater. In terms of the impact on humans and aquatic life are unfavorable both high and excessively low levels of water mineralization.
Prolonged use of drinking water and food products containing substantial amounts of nitrate (25 to 100 mg / dm3 of nitrogen), the concentration of methemoglobin in the blood increases dramatically. It is hard to occur methemoglobinemia in infants (especially bottle-fed formula milk, prepared on the water with a higher - about 200 mg / dm3 - nitrates) and in humans suffering from cardiovascular diseases.
The effects on humans are primary toxicity of nitrate ion itself; secondary, associated with the formation of nitrite ion, and tertiary, caused by the formation of nitrites and nitrosamines amines. Lethal nitrate dose for humans is 8-15 g; Acceptable Daily Intake on recommendations FAO / WHO - 5 mg / kg body weight.
The sulphate concentration in natural water is widely. The river waters and in the waters of freshwater lakes sulfate content often varies from 5-10 to 60 mg / dm3, in the rain waters - from 1 to 10 mg / dm3. The groundwater sulphate content often reaches much higher values. Elevated sulphate degrade the organoleptic properties of water and have a physiological effect on the human body. Since sulfate has laxative properties, its maximum allowable concentration is strictly regulated by laws and regulations.
Increased amounts of fluoride in water (1.5 mg / dm3) have harmful effects on humans and animals, causing bone disease (fluorosis). The fluorine content in drinking water is limited. However, very low levels of fluoride in drinking water (less than 0.01 mg / dm3) as detrimental impact on health, causing a risk of dental caries disease.
Increased amounts of fluoride in water (1.5 mg / dm3) have harmful effects on humans and animals, causing bone disease (fluorosis). The fluorine content in drinking water is limited. However, very low levels of fluoride in drinking water (less than 0.01 mg / dm3) as detrimental impact on health, causing a risk of dental caries disease. Typically, the stiffness dominates due to calcium ions (up to 70%); however, in some cases magnesium hardness may be 50 = 60%. The rigidity of the sea water and the ocean is much higher (tens to hundreds of mg-eq / dm3). The rigidity of the surface water is subject to appreciable seasonal fluctuations, generally reaching the maximum value at the end of winter and the lowest in the period of floods.
The high hardness of the water deteriorates the organoleptic properties of water, giving it a slightly bitter taste and having effects on the digestive organs.