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.
In some areas, the population only has one source of water. If this water is polluted, the population has no choice but to use that water. Sea water pollution also detroys the habitats of many species of fish and other animals. In some nations, fishing or harvesting of other animals is the main source of income.