Removal of mercury ion by the moss Pohlia flexuosa

The moss Pohlia flexuosa was obtained as the protonema from its matured capsules. It was grown by shaking in modified Murashige-Skoog's medium, and the dry weight obtained was 40 mg per 20 ml medium after 15 d. The mature protonema removed Hg²⁺ from aqueous solutions. The higher the initial Hg²⁺ concentration, the higher the amount of Hg²⁺ removed, and the concentration factor, which is an indicator of the ability to remove heavy metals, was 2000 ml/g of dry moss at 50 μg/ml of HgCl₂. The optimal pH and temperature for Hg²⁺ removal were 7.0 and 25°C, respectively. Sodium azide and dinitrophenol at 0.1 mM inhibited Hg²⁺ removal up to a relative removal of 81 and 77%, respectively. The importance of two processes, bioaccumulation and adsorption, in the removal of Hg²⁺ by this moss is discussed.