engleski

Speciation studies of copper in the Gulf of Elefsis: the role of the macroalgae Ulva rigida

The Gulf of Elefsis, situated in the vicinity of Athens, is a high productivity area regarding the biota. One of the most abundant algae existing there is Ulva rigida. Controlled laboratory simulation experiments, as well as field investigations indicated that copper is complexed to a high extent with organic substances. A significant part of these organic ligands exhibit surface active properties, i.e. the accumulation on different phase boundaries. The complexing capacity values of samples collected from different microenvironments within the Gulf of Elefsis, determined by the electrochemical method of differential pulse anodic stripping voltammetry (DPASV), vary between 0.04 and 0.43 µM Cu2+. At the same time, the complexing capacities of samples obtained from the laboratory tanks in which U. rigida has been placed under controlled conditions, show much higher complexing capacity values (up to 13 µM Cu2+). The surface active substances (SAS) expressed in equivalents of the nonionic surfactant Triton-X-100 were determined by out of phase a.c. voltammetry. Higher amounts of SAS were detected in the tanks containing U. rigida (up to 0.70 mg/L eq. T-X-100), in comparison to samples originating from natural microenvironments in the Gulf of Elefsis which had values ranging between 0.10 and 0.17 mg/L eq.T-X-100. These results show that U. rigida, contributes considerably to the production of ligands with high metal complexing capacity and high surfactant activity.

Gulf of Elefsis; Ulva rigida; copper; speciation; organics

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