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Environmental context determines the impact of titanium oxide and silver nanoparticles on the functioning of intertidal microalgal biofilms

Passarelli, Claire and Cui, Xianjin and Valsami-Jones, Eugenia and Underwood, Graham JC (2020) 'Environmental context determines the impact of titanium oxide and silver nanoparticles on the functioning of intertidal microalgal biofilms.' Environmental Science: Nano. ISSN 2051-8153

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Abstract

Coastal environments are receiving habitats for most nanoparticle (NP) waste. Coastal sediments, into which NPs accumulate, support microalgal biofilms that provide important ecosystem processes: primary production, enhanced sediment stabilisation, and nutrient recycling. We assessed the impact of realistic concentrations of titanium oxide (TiO₂) and silver (Ag) NPs on marine microalgal biofilms and associated ecosystem processes in simulated natural conditions, by exposing natural biofilms to TiO₂ and Ag-NPs for one-month periods in outdoor tidal mesocosms under three contrasted environmental contexts (seasons). Ag-NPs had no significant effects on microalgal biomass, sediment biostabilisation potential and sediment–water oxygen and nutrient fluxes, even at concentrations (25 μg l¯¹) higher than current estimated levels (25 ng l¯¹). TiO₂-NPs had no significant effect at current expected concentrations (25 μg l¯¹), but higher concentrations (25 mg l¯¹) resulted in decreased microalgal biomass; decreased ability of biofilms to biostabilise sediment, therefore limiting their coastal protection potential; reduced primary production and modified nutrient recycling. TiO₂-NPs impacts were dependent on the environmental context: most effect was seen in winter, while no toxicity on biofilms was demonstrated in early spring. Our findings demonstrate that while Ag-NPs, being liable to dissolution into Ag+ ions under the conditions tested, are not expected to have an environmental impact if current predictions of environmental loading prevail, TiO₂-NPs may have ecological consequences in coastal environments in addition to direct impacts on microbial biomass.

Item Type: Article
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Elements
Date Deposited: 15 Sep 2020 15:25
Last Modified: 15 Sep 2020 16:15
URI: http://repository.essex.ac.uk/id/eprint/28705

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