Main content area

Kinetics of cadmium accumulation and occurrence of dead cells in leaves of the submerged angiosperm Ruppia maritima

Malea, Paraskevi, Kevrekidis, Theodoros, Mogias, Athanasios, Adamakis, Ioannis-Dimosthenis S.
Botanica marina 2014 v.57 no.2 pp. 111-122
Ruppia maritima, bioaccumulation factor, cadmium, cell death, coastal water, enzyme kinetics, equations, leaves, regression analysis, risk, roots, seagrasses, toxicity
Cadmium accumulation and leaf cell death in the brackish water-submerged angiosperm Ruppia maritima L. were investigated under laboratory conditions exposed to increasing metal concentrations (2.22–355.88 μm). The Michaelis-Menten equation satisfactorily described accumulation kinetics in plant compartments (leaves, rhizome-stems, roots). Equilibrium concentration and uptake rate generally tended to increase, whereas bioconcentration factor at equilibrium decreased, as exposure concentration increased. The relationship between tissue concentration and the set of exposure concentrations and times was adequately described by multiple regression equations. Leaf cell death was observed after 3 or 5 days depending on dosage, but dead cell percentage was small after 9 days, suggesting a rather slow progress of cell death. The lowest leaf cadmium concentration associated with the onset of cell death was within the range of cadmium concentrations reported for seagrasses from various locations, implying that cadmium poses a risk to submerged angiosperms in coastal waters. However, toxicity appeared to be related to the rate of metal uptake rather than to total tissue concentration; an earlier onset of cell death at the highest exposure concentration was associated with the highest uptake rate, and dead cell percentage on the ninth day tended to increase with uptake rate. The data presented provide insights into metal accumulation by, and their effects on, submerged angiosperms colonizing coastal waters.