Constituents of Freshwater: Freshwater is the non-saline (i.e. contains very little percentage of salt chemicals) part of the planet-wide water cycle. Lakes, rivers, precipitation (ice, snow or rain), ponds, reservoir, springs and groundwater (wells and boreholes) are major sources of freshwater while oceans, seas, and many inland lakes are usually saline and are not freshwater sources.
Figure 1 shows that the freshwater sources contain only 2.5 per cent of the global water resources (i.e. 32, 000 out of 1385990.8 cubic kilometers).
Causes of Fresh water Pollution
Causes of freshwater pollution are many. This course material will highlight the pollutants of water and their sources.
As water travels over the surface of the land or through the ground, it dissolves naturally occurring as minerals and, in some cases, radioactive material. It can also pick up substances resulting from the presence of animals or human activity. Pollutants that may be present in water include:
Microbial Pollutants: These include viruses and bacteria that may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.
Inorganic Pollutants: These are salts and metals that can naturally occur or result from urban storm water runoff, industrial or domestic wastewater discharges, oil and gas production, mining or farming.
Read Also : Types of Wastewater and Motivational Factors for Recycling/Reuse
Pesticides and Herbicides: These may come from a variety of sources such as agriculture, urban storm water runoff, and residential uses.
Organic Chemical Pollutants: These include synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum production, and can also come from gas stations, urban storm water runoff, and septic systems.
Radioactive Pollutants: These can naturally occur or result from oil and gas production and mining activities.