If you add the valences of each atom in the molecular formula for arsenious acid, H 3 AsO 3, you can see that the molecule, which is uncharged, has a total valence state of 0 (3x(+1) for the hydrogen atoms; 1x(+3) for the arsenic(III) atom; 3x(-2) for the oxygen atoms = 3+3-6 = 0).
Eighty percent of sewage in India is untreated and flows directly into the nation's rivers, polluting the main sources of drinking water, a study by an environment watchdog showed Tuesday.
Water pollution is generally caused by human actives but may also be caused by natural resources. When water is polluted it is usually defined as either being polluted from point sources or non point sources. Point source pollution occurs from a specific location by a single source such as a large factory, oil refinery or hauling ship that contributed a massive amount of pollution within a single area.