Cadmium is in IIb group of Periodic table of the elements and belongs to group of transition metals, silvery-white colour. In nature, cadmium occurs in zinc, copper and lead ores. In elementary condition, cadmium is not soluble in water, until chlorides, nitrates and sulphates are soluble. On high pH value will sediment, because carbonates and hydroxides are indissoluble. As zinc, cadmium is using in electro industry, in many agents for washing, batteries, TV and yellow pigments. Also it is using in industry of ceramics, photographs, plastics, steals and alloys of copper, lead, silver, aluminium and nickel.
Origin in water
Cadmium occurs more in underground water then in surface waters, because cadmium presence in small concentration in rocks, coal and naphtha. Waters with low hardness and pH value can have higher value of cadmium concentration.
Cadmium absorption depends from solubility of its compounds.
With a high concentration of cadmium, qualm and retch occur at people. Cadmium is primary accumulating in kidneys and has long biologic time of half decomposition from10 to 35 years (kidney dysfunction, hypertension and anaemia).
Maximal allowable concentrations
According to recommendations of EU (Directive 98/83/EC) and according to our rules for drinking water (Sl. list SRJ 42/98), limitary value for cadmium is 5 mg/1, i.e. 3 mg/l respectively.