title: TiO2 nanoparticles for the remediation of eutrophic shallow freshwater systems: Efficiency and impacts on aquatic biota under a microcosm experiment.
abstract: The application of nanomaterials (NMs) in the remediation of eutrophic waters, particularly in the control of internal loading of nutrients, has been started, but limited investigations evaluated the effectiveness of these new treatment approaches and of their potential impacts on species from shallow freshwater lakes. The present work investigated, under a microcosm experiment, the application of a TiO2 nanomaterial both for reducing nutrient (mainly phosphorus and nitrogen forms) desorption and release from sediments (preventive treatment-PT) and for eliminating algal blooms (remediation treatment-RT). Furthermore, we also intended to assess the potential impacts of nano-TiO2 application on key freshwater species. The results showed the effectiveness of nano-TiO2 in controlling the release of phosphates from surface sediment and the subsequent reduction of total phosphorus in the water column. A reduction in total nitrogen was also observed. Such changes in nutrient dynamics contributed to a progressive inhibition of development of algae after the application of the NM in PT microcosms. Concerning the ability of nano-TiO2 to interact with algal cells, this interaction has likely occurred, mainly in RT, enhancing the formation of aggregates and their rapid settlement, thus reducing the algal bloom. Both treatments caused deleterious effects on freshwater species. In PT, Daphnia magna and Lemna minor showed a significant inhibition of several endpoints. Conversely, no inhibitory effect on the growth of Chironomus riparius was recorded. In opposite, C. riparius was the most affected species in RT microcosms. Such difference was probably caused by the formation of larger TiO2-algae aggregates in RT, under a high algal density, that rapidly settled in the sediment, becoming less available for pelagic species. In summary, despite the effectiveness of both treatments in controlling internal nutrient loading and in the mitigating algal bloom episodes, their negative effects on biota have to be seriously taken into account.
authors.affiliation: Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: marciabessa@ua.pt.
authors.forename: Márcia
authors.initials: M
authors.lastname: Bessa da Silva
authors.affiliation: CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; Department of Environment and Planning, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Nelson
authors.initials: N
authors.lastname: Abrantes
authors.affiliation: Department of Biology & GreenUP/CITAB-UP, Porto, Portugal, Faculty of Science, University of Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal; CIIMAR (Interdisciplinary Centre of Marine and Environmental Research), University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal.
authors.forename: Verónica
authors.initials: V
authors.lastname: Nogueira
authors.affiliation: Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; CESAM (Centre of Environmental and Marine Studies), University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Fernando
authors.initials: F
authors.lastname: Gonçalves
authors.affiliation: Department of Biology & GreenUP/CITAB-UP, Porto, Portugal, Faculty of Science, University of Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal; CIIMAR (Interdisciplinary Centre of Marine and Environmental Research), University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal.
authors.forename: Ruth
authors.initials: R
authors.lastname: Pereira
mesh_terms: D000818:Animals; D058448:Biota / Q000187:drug effects; D002683:Chironomidae / Q000187:drug effects; D003621:Daphnia / Q000187:drug effects; D052918:Environmental Restoration and Remediation; D005068:Eutrophication / Q000187:drug effects*; D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D009584:Nitrogen / Q000494:pharmacology; D010758:Phosphorus / Q000494:pharmacology; D011174:Portugal; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D010758:Phosphorus; D014025:Titanium; D009584:Nitrogen
keywords: Ecotoxicological impacts; Eutrophic systems; Microcosm experiments; Nanomaterials; Remediation