Comparison of TNT removal from seawater by three marine macroalgae

Axenic plantlets derived from three species of marine macroalgae, the temperate green alga Acrosiphonia coalita, the temperate red alga Porphyra yezoensis, and the tropical red alga Portieria hornemannii, all possessed a similar metabolic route to remove the explosive compound 2,4,6-trinitrotolune (TNT) from seawater. At a biomass density of 1.2 g l−1 and initial TNT concentrations of 10 mg l−1 or less, TNT removal from seawater was 100% within 72 h for P. hornemannii and P. yezoensis. Specific rate constants for TNT uptake were 0.016–0.018 l g−1 FW h−1 for A. coalita filaments, 0.047–0.062 l g−1 FW h−1 for P. yezoensis blades, and 0.037–0.049 l g−1 FW h−1 for P. hornemannii microplantlets. Only trace amounts of TNT were found within the biomass. All species reduced TNT to 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dintrotoluene, but these products never accounted for more than 20% of the initial TNT.