Copper binding ability of the extracellular organic matter released by Skeletonema costatum

Abstract

The copper complexing ability of the exudates produced during the exponential growth phase by Skeletonema costatum has been investigated by a ligand-competition technique involving copper sorption onto C-18 Sep-Pak cartridges. Two ligands with different affinity for copper were required for the best fit of the copper complexation data in seawater with and without exudates: a strong ligand with a log K close to 13 and a weaker ligand with a log K close to 9. The culture increased both L 1 and L2 ligand concentrations, already present in seawater, by a factor close to 4 after the first 72 hours of growth. The presence of class 1 stronger ligands in copper binding organics produced by the diatom is discussed in relation to natural copper speciation in the sea.

Dunaliella salina as marine microalga highly tolerant to but a poor remover of cadmium

“…In this way, this microalga should have some protective system against the cadmium toxicity that prevents the metal accumulation to the interior of cell. One of those possible mechanisms is the development of a number of routes and modes for excreting metals [41]. A more common method in eukaryotes is either active or passive excretion of metals [42].…”

Heavy Metal Tolerance in Algae

“…A particular organism usually produces a specific kind of ligand, but sometimes more than one type of ligand may be produced by one organism (Morelli et al 1989). A particular organism usually produces a specific kind of ligand, but sometimes more than one type of ligand may be produced by one organism (Morelli et al 1989).…”

A comprehensive systematic compilation of complexation parameters reported for trace metals in natural waters

“…Gordon et al, 1996;Midorikawa and Tanoue, 1996)); sorption onto C 18 (hydrophobic organic material and metalorganic complexes are adsorbed, then recovered by elution with methanol, and metal content quantified (e.g. Sunda and Hanson, 1987;Hanson et al, 1988;Morelli et al, 1989)). On consideration of this range of measurement techniques which has been employed for studies on natural waters, it is evident that each particular method will access a different fraction of the total complexes present, and hence wide dispersion in the resulting complexation parameters calculated from these data can be expected (see Discussion).…”