Effect of Pseudokirchneriella subcapitata (Chlorophyceae) exudates on metal toxicity and colloid aggregation

Article Article scientifique Article Effect of Pseudokirchneriella subcapitata (Chlorophyceae) exudates on metal toxicity and colloid aggregation eng 2007 author Koukal Brahim 130708 author Rosse Patrick 520412 author Reinhardt Alain 516949 author Ferrari Benoît 134598 author Wilkinson Kevin 29725 author Loizeau Jean-Luc 0000-0002-0611-0388 23020 author Dominik Janusz 22088 63-70 10.1016/j.watres.2006.09.014 0043-1354 http://linkinghub.elsevier.com/retrieve/pii/S0043135406005331 The effects of Pseudokirchneriella subcapitata exudates on the acute toxicity of metals (Cd,Cu, Pb and Zn) were studied using (1 h) algal photosynthesis inhibition tests. The metal concentrations tested were 30, 60, 120, 250 and 500 mg/L for Cd and Zn; and 500, 1000, 2000, 3000, 4000 mg/L for Cu and Pb. It was established that P. subcapitata exudates markedly decreased metal toxicity. This effect was ascribed to: (i) the presence of organic ligands that bind metals and reduce the concentration of free ionic metal, and/or (ii) interaction of exudates with the cell surface with a subsequent decrease in metal uptake. The effects of the exudates on colloid aggregation were also examined using two different types of single particle counters (SPC). Exudates facilitated the colloid removal, likely via acceleration of aggregation (bridging). The results clearly demonstrate that algal exudates play an important role in the biogeochemical cycling of metals in natural surface water: (1) by reducing free metal concentrations and toxicity to living organisms and (2) by favoring colloid aggregation leading to the removal of colloid-bound metals (colloidal pumping). Such results highlight one potential application of the algae in the remediation of metalcontaminated waters. The results also suggest that current algal toxicity testing protocols, in particular long-term and static tests, may underestimate metal toxicity because of the presence of algal exudates. Aggregation Carbohydrates Dissolved organic matter Metals Proteins Pseudokirchneriella subcapitata Toxicity Dewey 540 Dewey 550 40 Département de chimie minérale, analytique et appliquée 145 41 Département F.-A. Forel des sciences de l'environnement et de l'eau 153 false Water research 41 1 f1da86be-9655-496e-93ae-388144588ba7 Article (Published version) Restricted Koukal et al 2007 Wat Res.pdf 327432 application/pdf restrictedAccess Faculté des sciences / Section de chimie et biochimie / Département de chimie minérale, analytique et appliquée Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département F.-A. Forel des sciences de l'environnement et de l'eau

Title	Published in	Year	Views	Downloads

Effect of Pseudokirchneriella subcapitata (Chlorophyceae) exudates on metal toxicity and colloid aggregation	Water research	2007	864	1
Contrasting roles of natural organic matter on colloidal stabilization and flocculation in freshwaters		2004	1,499	1,316

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Reinhardt, Alain