Role of algae in fate of carcinogenic polycyclic aromatic hydrocarbons in the aquatic environment.

Polycyclic aromatic hydrocarbons (PAHs) represent an ecotoxicologically relevant, combustion-related substance group. The bioconcentration and transformation of a priority PAH, benzo[a]pyrene (BaP), by brown (Fucus vesiculosus and Chorda filum), red (Furcellaria lumbricalis), green (Enteromorpha intestinalis, and Cladophora glomerata), and chara (Chara aspera) algae have been studied. A flux budget was made of the amounts of BaP that are accumulated and metabolized by different algae during an estimated time. The results indicated that of all the BaP consumed, 89-99% was found in the biomass of Fucus, an insignificant part was in the solution, and the remainder (up to 4%) was not recovered, i.e., was considered to have been metabolized. For green and chara algae the proportion of transformed PAHs was more essential, 42-49%. The transformation of BaP in marine and freshwater algae is species specific and depends on the presence and activity of enzymes localized in the plant cells. The most important enzyme systems for detoxification of BaP are o-diphenol oxidase, cytochrome P450, and peroxidase. The data obtained indicate the important role of marine and freshwater algae in the fate of carcinogenic PAHs in the environment. Copyright 1998 Academic Press.