Relation between colour and visible absorbance

The origin of the colour can be related to one coloured product or pollutant, or to natural constituents (humic substances, metallic ions or complexes, for instance). The colour is well defined when only one coloured solute is present but, generally, several compounds are responsible for a mixture of colours giving a broad visible spectrum (Fig. 3). 

Sample Tristimulus coordinates Dorn, l Purity Colour hue 

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