ABSTRACT
The aquatic environment has played a crucial role since the very beginning of civilization. Leonardo da Vinci compared water with blood when he said: “water is the blood of the soil.” Indeed, “water” must have been one of the rst words invented by human. Nowadays, the word water is commonly
used in two meanings. First, in a purely chemical sense, it represents the simple chemical compound with the formula H2O. Second, it stands for a wide range of different aqueous solutions, whose composition determines their usefulness or uselessness for a given purpose. The speci c names of the solutions relate to the source or usage, for example, sea water, river water, ground water, rain water, drinking water, and irrigation water.
