Volatile Odorous Excretion Products of Algae and Their Occurrence in the Natural Aquatic Environment

Members of many algal groups (Chrysophyceae, Cryptophyceae, Dinophyceae, Chlorophyceae and Bacillariophyceae) have been reported to impart characteristic odours to water when blooms of these organisms occur. The volatile compounds isolated from algal cultures under controlled laboratory conditions and from surface waters during algal bloom periods are listed. The substances identified as responsible for odour problems are alkenes, saturated and unsaturated aliphatic alcohols, aldehydes, ketones, esters, thioesters and sulfides. Experimental conditions and criteria enabling one to distinguish between algal excretion products and contaminants, or pollution products are put forward.