Fate of Model Xenobiotics in Calcareous Marine Algae

Abstract

Uptake, depuration, and metabolism of p-nitroanisole (PNA) and p-nitrophenol (PNP) were investigated in Halimeda, Padina, and Porolithon species, all of which are calcareous marine algae found in tropical waters . The algae were exposed to filtered seawater solutions of either PNA or PNP in a static system for 24 hr (uptake period), then placed in clean water and allowed to release absorbed chemical and possible metabolites for 24 hr (depuration period). Concentrations of the chemicals were monitored spectrophotometrically, and the water at the end of uptake and depuration was extracted onto a column of Amberlite XAD-4 resin, eluted sequentially with methylene chloride and methanol, and analyzed for metabolites by high-pressure liquid chromatography (HPLC). Results showed that the algae absorb PNA but not PNP. There was no indication that they were capable of metabolizing PNA, except inconsistently, to PNP. However, half of the absorbed PNA remained unaccounted for, and may either have been metabolized to undetected metabolites or bound to tissue macromolecules.