UPTAKE AND RELEASE KINETICS OF COPPER BY THE AQUATIC MOSS FONTINALIS-ANTIPYRETICA

Copper uptake and release rates by Fontinalis antipyretica were invest igated. A contamination stage in which the plants were exposed to Cu c oncentrations in the range 0.09-0.75 mg l(-1) was followed by a decont amination period, exposing the plants to metal-free water. Tanks were operated in perfectly mixed conditions and the illumination at water s urface was 740 lux. Short and long duration experiments (217 and 1008 h, respectively) were carried out with plants collected in May and Aug ust, respectively. A simple mass transfer model was fitted to the expe rimental results in order to determine the uptake and release rate con stants, k(1) and k(2), the Cu concentration at the end of the uptake p hase, C-mu, and the equilibrium concentrations, C-me and C-mr, for the contamination and decontamination stages, respectively. In the short duration experiment, k(1) decreased from 846 to 628 h(-1) as Cu concen tration increased from 0.14 to 0.60 mg l(-1) In the long duration one, with plants in different physiological conditions, k(1) decreased Fro m 448 to 293 h(-1) as Cu concentration increased from 0.09 to 0.75 mg l(-1). The release rate constant, k(2), appears not to depend on the C u concentration and averaged 0.020 and 0.011 h(-1) in the first and se cond experiments, respectively. The ratio k(1)/k(2) represents a bioco ncentration factor, BCF (Cu concentration in the plant, dry wt/Cu conc entration in the water). BCF values ranged between 40,000 and 30,000. A biological elimination factor (BEF = 1-(C-mr/C-mu) was also calculat ed. BEF values slightly increased with C-mu, varying from 0.58 to 0.62 (5203 < C-mu < 15762 mg kg(-1) dry wt.) and from 0.46 to 0.66 (3127 < C-mu <23773 mg kg(-1) dry wt.) in the short and long duration experim ents, respectively. (C) 1998 Elsevier Science Ltd. All rights reserved .