Source
The source of almost all fresh water is precipitation from the atmosphere, in the form of mist, rain and snow. Fresh water falling as mist, rain or snow contains materials dissolved from the atmosphere and material from the sea and land over which the rain bearing clouds have traveled. In industrialized areas rain is typically acidic because of dissolved oxides of sulfur and nitrogen formed from burning of fossil fuels in cars, factories, trains and aircraft and from the atmospheric emissions of industry. In some cases this acid rain results in pollution of lakes and rivers.
In coastal areas fresh water may contain significant concentrations of salts derived from the sea if windy conditions have lifted drops of seawater into the rain-bearing clouds. This can give rise to elevated concentrations of sodium, chloride, magnesium and sulfate as well as many other compounds in smaller concentrations.
In desert areas, or areas with impoverished or dusty soils, rain-bearing winds can pick up sand and dust and this can be deposited elsewhere in precipitation and causing the freshwater flow to be measurably contaminated both by insoluble solids but also by the soluble components of those soils. Significant quantities of iron may be transported in this way including the well-documented transfer of iron-rich rainfall falling in Brazil derived from sand-storms in the Sahara in north Africa.
Read more about this topic: Fresh Water
Famous quotes containing the word source:
“Please don’t look at me as if you had a source of income other than your salary.”
—Joseph L. Mankiewicz, U.S. director, screenwriter. Joseph L. Mankiewicz. Countess (Danielle Darrieux)
“There often seems to be a playfulness to wise people, as if either their equanimity has as its source this playfulness or the playfulness flows from the equanimity; and they can persuade other people who are in a state of agitation to calm down and manage a smile.”
—Edward Hoagland (b. 1932)
“Being the dependents of the general government, and looking to its treasury as the source of all their emoluments, the state officers, under whatever names they might pass and by whatever forms their duties might be prescribed, would in effect be the mere stipendiaries and instruments of the central power.”
—Andrew Jackson (1767–1845)