What changes occur in natural water under the influence of human activities?

Under the influence of human activities in natural water, the following changes occur:
• fresh water is polluted by sulfuric and nitric acids from the atmosphere, the content of sulfates and nitrates in them increases;
• in underground and river waters, the content of calcium, magnesium, silicon increases due to leaching and dissolution of these substances with acidified rainwater;
• the water contains an increase in the content of heavy metals, primarily lead, cadmium, mercury, arsenic and zinc;
• in surface and underground waters, the content of salts coming from wastewater from the atmosphere and due to the washing away of solid waste increases;
• the water increases the content of organic compounds, especially biologically resistant (pesticides, their decomposition products and other toxic, carcinogenic and mutagenic substances);
• reduction of oxygen content in water, primarily as a result of an increase in its consumption for oxidative processes;
• deterioration of the transparency of water in water bodies, which leads to the multiplication of viruses and bacteria – pathogens of infectious diseases;
• water pollution by radioactive isotopes.

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