Behaviour of CeO2 nanoparticles and bulk and their toxicity in freshwater and seawater microalgae

Trabajo presentado en el XVIII Seminario Ibérico de Química Marina, celebrado en Alicante (España) de 20 al 22 de julio de 2016.The production of manufactured nanomaterials has risen exponentially in recent years. Despite this growth, information regarding the fate and behavior of nanoparticles (NPs) in freshwater and marine environment is still limited. CeO2 NPs are used for polishing and decolorizing glass, opacifier in vitreous enamels and photochromic glasses, heat-resistant alloy coatings; as a cracking catalyst, as a catalyst for automobile emission control, in ceramic coatings, in phosphors, in cathodes, in capacitors, in semiconductors, in refractory oxides, gemstone polishing. The aim of the current study was to assess the toxicity of CeO2 in two species of microalgae from freshwater to marine microalgae Three aspects were studied under laboratory conditions, I) CeO2 NPs and Bulk behavior in different culture media used for bioassays, II) toxicity of different type of CeO2 NPs and bulk and III) quantification of intracellular and extracellular NPs and Bulk CeO2. The experiment was performed for two microalgae. Phaeodactylum tricornutum, and Chlamydomonas reinhardtii, seawater and freshwater species respectively. Both studies were carried out under white light illumination. CeO2 aggregation rate was increased by ionic strength. Moreover, the presence of algal cells affects the stability of CeO2 suspensions, where heteroagglomeration process were present as the first mechanism of NP-cell interaction. Both, nano and bulk CeO2 formed aggregates during incubation, but CeO2 NPs formed large aggregates trapped almost completely between algae more than bulk CeO2 did, because NPs are more bioavailable over bioassays.This work was supported by PE2011-RNM-7812 project and Spanish National Research Plan (MINECO) CTM2012-38720-C03-03. The ERF funds has been supported this project.N