The problem of pollution of freshwater affects humans directly, due to the great demand, ever-growing, of water for domestic, agricultural and industrial use.
Think of the difference between pastoral and industrialized societies: they are requiring about 100 liters per day pro capite, and exaggerated with considerable waste.
The first testimonies of the presence of pollution were found in the glaciers and snowy sheets: toxic substances suspended in the atmosphere falls slowly, by gravity or with rains and snows.
This is easily verifiable: in ice formed in 1900, in a Greenland glacier, traces of lead compounds are subtle. Into those formed in 1975 are present in concentration four times higher.
Traces of harmful substances, as well as the atmosphere and oceans, also found in the tissues of plants and terrestrial animals.
The sources of pollution of rivers and lakes are: urban residual waters, wastewater, water industries that derive from agriculture.
Widespread, in lakes, is eutrophication: this process, caused by excess nutrients, produces a strong growth of algae that stain the waters and deplete oxygen.
A major source of pollution in the waters is the presence of toxic metals such as selenium, lead, cadmium, mercury
Pollution of lakes is very worrying, accentuated by the massive presence of recreational boats who unload light hydrocarbons, more harmful than heavy ones.
Not to be forgotten is pollution from pesticides and insecticides, which on the one hand, have eliminated the presence of diseases such as malaria, on the other hand have downloaded in high doses substances that have caused the deaths of guests to freshwater.
River pollution due to discharges of industries, primarily to wastewater from agriculture and suburban discharges (in addition to organic products include the abundant detergents).
The overall situation is fortunately improved from 90, but the problem exists, and not just for large rivers.
The aquifers are in direct relationship with surface water and this can easily be polluted, causing a huge problem for humans: their pollution depends, as well as by men, even from the soil composition (more or less impermeable).
The potential sources of groundwater pollution are: losing wells, the methods of disposal of solid wastes (landfills), wastewater in agriculture, oil pollution, and in a speech in hand, radioactive waste produced by nuclear power plants.
Finally the industrial civilization not only benefits but also raises major problems for humanity.