Uptake and Metabolism of DDT by Six Species of Marine Algae

The uptake and metabolism of DDT by six species of marine phytoplankton was studied. Uptake of DDT by the various species increased linearly with an increasing concentration of DDT but nonlinearly with an increasing concentration of cells. The species with the higher numbers of cells per unit of mass took up greater amounts of DDT per unit weight than species with lower numbers of cells. All species concentrated DDT to levels many times higher than the original concentration in the medium. DDT was accumulated by the six species in the following order: Skeletonema costatum > Cyclotella nana > Isochrysis galbana > Olisthodiscus luteus > Amphidinium carteri > Tetraselmis chuii. All of the species converted small amounts of DDT to DDE. After 24 days of treatment, the amount of DDE produced by different species ranged from 0.03 to 12% of the total DDT in the cells. Maximum conversion of DDT to DDE was observed in cultures of Tetraselmis.