Characterization of phytoplankton exudates and carbohydrates in relation to their complexation of copper, cadmium and iron

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 408:33-46 (2010) - DOI: https://doi.org/10.3354/meps08555 Characterization of phytoplankton exudates and carbohydrates in relation to their complexation of copper, cadmium and iron Slađana Strmečki1, Marta Plavšić1,*, Sebastian Steigenberger2,3, Uta Passow2,4 1Ruđer Bošković Institute, Center for Marine and Environ. Research, Zagreb, 10002 Zagreb, Croatia 2Alfred Wegener Institute for Polar and Marine Research, 27570 Bremerhaven, Germany 3Present address: National Oceanography Centre, Southampton, University of Southampton, Waterfront Campus, Southampton, SO14 3ZH, UK 4Present address: Marine Science Institute, University of California, Santa Barbara, California 93106, USA *Corresponding author. Email: plavsic@irb.hr ABSTRACT: The goal of this study was to investigate if transparent exopolymer particles (TEP), carbohydrates, surface-active substances (SAS), reduced sulfur species (RSS), or thio/amino groups contribute significantly to the complexing capacity of phytoplankton exudates for Cu (LTOTCu), Cd (LTOTCd), or Fe (LTOTFe). Complexing capacities and apparent stability constants (Kapp) were determined electrochemically for Cu and Cd in cultures of the marine diatoms Thalassiosira weissflogii and Skeletonema costatum, and in a culture of the coccolithophore Emiliana huxleyi. Furthermore, the complexing capacity with Fe, Cu and Cd of 4 marine polysaccharides (PS) (phytagel, carrageenan, laminarin and alginic acid) was investigated. As expected, more Cu than Cd was complexed in the 3 phytoplankton cultures and in the phytagel solution. Size fractionation of the phytagel solution suggests that the binding capacity for Cu was more significant in the particulate fraction (>0.7 µm), indicating that Cu was preferably trapped within pores and channels of large hydrogels. In contrast, Cd binding sites were predominantly found in the fraction <0.7 µm, suggesting binding to the outer surfaces of gel particles to be of greater importance for larger ions. The Kapp of the Cd complexes were higher than those of Cu, indicating stronger binding of Cd ions than of Cu ions. Solutions of carrageenan, laminarin and alginic acid did not form complexes with either Cu or Cd, and Fe-binding properties could not be detected for any of the 4 polysaccharide solutions. Thio/amino groups of sulfur-rich ‘glutathione’ type ligands were found in all phytoplankton cultures and were presumably responsible for the complexation of Cu. No consistent relationship was observed between TEP, carbohydrate concentration, SAS or sulfur content, or with the complexing capacity, emphasizing the high degree of heterogeneity of substance classes responsible for metal binding. KEY WORDS: Complexation · Copper · Cadmium · Iron · Carbohydrate · TEP · Electrochemical method Full text in pdf format PreviousNextCite this article as: Strmečki S, Plavšić M, Steigenberger S, Passow U (2010) Characterization of phytoplankton exudates and carbohydrates in relation to their complexation of copper, cadmium and iron. Mar Ecol Prog Ser 408:33-46. https://doi.org/10.3354/meps08555 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 408. Online publication date: June 03, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.