Chemistry of water -Part 11-

Despite the fact that water covers 72 percent of the Earth's surface, the proportion of potable water does not reach 3.5 percent of the total water reserve.
The world has been experiencing an increasing scarcity of drinking water over the last few decades. Fresh water now accounts for less than 3.5 percent of the Earth's water reserves, and it does not reach everyone, as 20 percent of the world's population lacks it. On the other side, due to sewage or manufacturing waste in rivers and other sources of fresh water, the phenomena of drinking water contamination is spreading in disadvantaged communities. According to the World Health Organization, drinking water pollution is responsible for four-fifths of all diseases worldwide.

A stream in the town of Amlwch, Anglesey which is contaminated by acid mine drainage from the former copper mine at nearby Parys Mountain.

Natural waters and pollution:

Before it reaches the ground, the relatively pure liquid water that condenses at an altitude dissolved gases and bind soluble and insoluble compounds from the air. Nitrogen oxides, hydrogen sulfide, and sulfurous gases from industry can contaminate this water. Furthermore, soil dust may contain organic material and minerals. Water is deemed contaminated if it contains alien elements. Dissolved and suspended inorganic debris, organic matter, bacteria, algae, and parasites are all examples of pollutants. These pollutants are produced as a result of agricultural, industrial, and human activity. Thus, among the major contributors of water contamination are manufacturing waste, pesticide residues, fertilizers, soil conditioners, human waste, and transportation exhausts.

The movement of chemical elements from the lithosphere to the oceans is made possible by water's properties as a transport and transformation agent. And the water is ionized while it is being circulated.

Due to clays, organic waste from agriculture and plants, and generally abundant microorganisms, surface waters are frequently cloudy. And as a result of their equilibrium with air, which has a carbon dioxide content of only approximately 0.03 percent and a 21 percent oxygen content, surface waters are distinguished by having a high oxygen level and a low carbon dioxide content.

Depending on the soil in the area, phreatic waters have extremely different chemical compositions; they typically no longer have any turbidity, but surface contamination is a common occurrence.

  • The most often found dissolved particles are bicarbonates of: calcium Ca(HCO3)2, manganous Mn(HCO3)2, ferrous Fe(HCO3)2, sodium Na(HCO3)2 and magnesium Mg(HCO3)2. Also, sulfates (CaSO4; Na2SO4; MgSO4), chlorides (NaCl; MgCl2; CaCl2), and silicates (Na2SiO3; H2SiO3). In addition, there are fluorides, nitrates, and nitrites.

Sources of contamination of drinking water with organic matter:

  • Sewage waste is drained into the water source.
  • the organic decay of aquatic organisms that have died.
  • chemicals and fertilizers that seep into the water from the land.
  • manufacturing waste being discharged into the water supply.


  • [General and inorganic chemistry book- M. Shkhashirou- H. Birqdad- Y. Qodsi- University publications. Algeria]

  • [AQUAPROX- Livre: Traitement des eaux de refroidissement. Imprimé en France par EMD S.A.S- 53110 Lassay-les-Chateaux. N° d'imprimeur: 15566- Dépot légal: juin 2006. N° 842- Cyclus print 90°]

  • [GÉOCHIMIE DES EAUX CONTINENTALES- Nathalie Gassama. ISBN 9782340-047402 ©Ellipses Édition Marketing S.A., 2021. 8/10 rue la Quintinie 75015 Paris]

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