Biokinetics of selected heavy metals and radionuclides in the common Mediterranean echinoid Paracentrotus lividus: sea water and food exposures

Abstract

Uptake and loss kinetics of Zn, Ag, Cd, '=CS, and 241Am by the echinoid Paracentrotus lividus contaminated through either water or food were determined in controlled laboratory radiotracer experiments using low contaminant concentrations. The echinoid efficiently accumulated most of the elements from water. The only exception was '"CS (concentration factor at steady state = 2.71. With respect to relative metal bioavailability, concentrations in the different body compartments of P lividus were generally ranked in the order: digestive wall > gonads 2 body wall >Aristotle's lantern > coelomlc fluid. However, for2''~rn, body wall uptake was as efficient as that of the digestive wall. The loss kinetics for Zn, Ag, and 1 3 4~s were described by a 2-component model whereas loss of Cd and '"'Am was linear during the time course of the experiment. Loss of the different elements was relatively slow, except for 134Cs, whose long-lived loss component was characterized by a biological half-life of 6 d. Loss of the different elements ingested wlth food was described by a single-component model for Cd, '34Cs, and &;'.Am and by a 2-component model for Zn and Ag. Parameters of the kinetics ~n d~c a t e that all (for Cd, I3Ts, and 'j1.4m) or most (for Zn and Ag) of the ingested amount of element is readily lost from the organism with the faeces. However, estimation of the assimilated fraction of elements ingested by the echlnoids suggests that food could contr~bute significantly to the total body burden of Ag in f? lividus.

Modeling radiocesium bioaccumulation in a marine food chain

“…Rapid turnover of radiocesium was also found in many bivalve species (Bryan 1963, Harrison 1972, Cranmore & Harrison 1975. Similarly, Warnau et al (1996) reported that the depuration rate constant of radiocesium in the echinoid Paracentrotus lividus was 0.116 d -1…”

Biokinetics of zinc and cadmium accumulation and depuration at different stages in the life cycle of the cuttlefish Sepia officinalis

“…In other invertebrates such as echinoderms or bivalves, the major fraction of the radiotracers was found in the calcified parts, i.e. the body wall of sea urchins (Warnau et al 1996) and the shell of mussels . Although the cuttlefish Sepia officinalis has a calcareous compartment (the cuttlebone) representing ca.…”

“…In contrast to most marine invertebrates, which accumulate Cd mainly from seawater (Dahlgaard 1981, Nolan & Dahlgaard 1991, Warnau et al 1996, cephalopods such as Sepia officinalis accumulate Cd principally from food. Once incorporated, the fate of this metal is mainly controlled by the digestive gland, which acts as an efficient detoxification organ whatever the source of Cd (seawater, food, or sediment).…”

“…This essential element has chemical properties similar to those of Cd that, in turn, could interfere with Zn metabolism (Nieboer & Richardson 1980). Biokinetics were determined using carrier-free radiotracers in order to measure element fluxes in real time at environmentally realistic contaminant concentrations , Warnau et al 1996.…”

Effects of increased <i>p</i>CO<sub>2</sub> and temperature on trace element (Ag, Cd and Zn) bioaccumulation in the eggs of the common cuttlefish, <i>Sepia officinalis</i>

“…counted in 150 ml of seawater) before and after each water renewal in order to determine the time-integrated radiotracer activities, i.e. the mean value of all measurements performed over the time period considered (Warnau et al, 1996). At different time intervals, the three radionuclide activities were counted in 3 dissected eggs (γ -emitters could be detected in the same sample according their γ -emissions energy) to determine the radiotracer distribution between the eggshell and vitellus or among eggshell, vitellus, embryo and peri-vitelline fluid, i.e.…”