La contaminacion

Contamination is considered every damaging change produced physically, quimically and biologically speaking within life resources, that is to say, air, land and water.   Contamination is the presence of a minor and unwanted constituent in another material, metal, chemical or mixture, often at the trace level. In chemistry, the term usually describes a single chemical, but inspecialized fields the term can also mean chemical mixtures, even up to the level of cellular materials.

Water pollution is the contamination of water bodies (e.g. lakes, rivers,oceans, groundwater).
Water pollution affects plants and organisms living in these bodies of water; and, in almost all cases the effect is damaging either to individual species and populations, but alsoto the natural biological communities.
Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds.

Waterpollution categories

Surface water and groundwater have often been studied and managed as separate resources, although they are interrelated.[7] Sources of surface water pollution are generallygrouped into two categories based on their origin.
Point source pollution refers to contaminants that enter a waterway through a discrete conveyance, such as a pipe or ditch. Examples of sources in thiscategory include discharges from a sewage treatment plant, a factory, or a city storm drain. The U.S. Clean Water Act (CWA) defines point source for regulatory enforcement purposes.[8] The CWAdefinition of point source was amended in 1987 to include municipal storm sewer systems, as well as industrial stormwater, such as from construction sites.[9]

Non-point source pollution

Non-pointsource (NPS) pollution refers to diffuse contamination that does not originate from a single discrete source. NPS pollution is often the cumulative effect of small amounts of contaminants gathered from a...