Naslov
Interaction of cadmium and copper with surface active organic matter and complexing ligands released by marine phytoplankton.

Autori
Kozarac, Zlatica ; Plavšić, Marta ; Ćosović, Božena ; Viličić, Damir

Izvornik
Marine chemistry (0304-4203) 26 (1989), 4; 313-330

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
copper; cadmium; surface active substances; ligands; phytoplankton; voltammetry

Sažetak
The organic matter released by the marine phytoplankton species Dunaliella tertiolecta and its physico-chemical interaction with cadmium and copper ions were studied by electrochemical methods (differential pulse anodic stripping voltammetry (DPASV) and a.c. polarography). The interactions with cadmium and copper were studied at the model interface (mercury electrodesolution) and in the bulk phase by measuring the complexing ability of the released organic material. The axenic cultures were grown on different growth media, without and with trace metals and chelators. Culture media were analyzed 10 days after inoculation, containing ∼5 × 105−1.2 × 106 cells cm−3 when untreated or after separation of cells by gentle centrifugation. It was found that the content and type of the released surface-active material and complexing ligands depend on the initial composition of the growth media. In all cases, strong interaction of excreted organic substances with copper in the bulk phase and with cadmium at the model interface were observed. A rather high value of the complexing capacity, 9.5 × 10−7 mol Cu2+ dm−3, was found in the culture grown on medium without trace metals and chelators (medium I) whereas the surface activity of this culture was not high (0.2 mg dm−3 equivalent to Triton-X-100). Higher contents of surface-active material (0.8 and 1.0 mg dm−3) were found in cultures grown in media with trace metals and without chelators (II and III), accompanied by a high content of complexing ligands (5.8 × 10−7 and 9.5 × 10−7 mol Cu2+ dm−3). However, if the complexing capacity is calculated per cell the values obtained for cultures grown in media II and III (0.79 × 10−15 and 0.98 × 10−15 mol Cu2+ dm−3) are lower than for cultures grown on medium I (1.8 × 10−15 mol Cu2− dm−3). The exceptional adsorption effects and the copper complexing capacity for medium 1, and the presence of cells with degenerative symptoms can be ascribed to stressed growth conditions, and, particularly, to deficiency of metals. A qualitatively similar behaviour has been observed in natural samples of estuarine waters, indicating the existence of stressed conditions during the mixing of fresh and saline waters.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA