No abstract

No abstract

In the present study, the main goal was to compare the effects of ionic copper versus copper nanoparticles in Enchytraeus albidus assessing the effect at the biomarker level, testing different concentrations and exposure times. Measured parameters were lipid peroxidation (LPO), total, reduced and oxidized glutathione content (TG, GSH and GSSG), the enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione S-transferases (GSTs) and cholinesterases (ChEs). Results showed that both salt- and nano-copper caused oxidative stress and damage to E. albidus, as confirmed by LPO levels, and effects could be discriminated between the copper forms. Nevertheless and despite the visible discrimination between nano and the salt form (time and exposure dependent), there was no single or a set of biomarkers that provided the best discrimination.

The nano-form of copper (Cu-NPs) is already extensively used. In this paper the toxic effect of Cu in the worm Enchytraeus crypticus (Oligochaeta: Enchytraeidae) was assessed following exposure to (1) Cu-salt: freshly spiked soil with copper-nitrate, (2) Cu-NPs: freshly spiked soil with Cu nanoparticles (80nm), and (3) Cu-field: historically Cu contaminated soil (80years ago). Our main aims were to compare the three different exposure regimes and respective toxicity, and to determine how the oxidation state of the Cu and dissolution state of the particles differed. Characterization of in situ-exposure included identification of oxidation states with synchrotron generated X-ray absorption near-edge spectroscopy (XANES) analysis, activity of free Cu(2+) in soil-solution (Ion Selective Electrode), and the relative distribution of the labile Cu-fractions (Sequential Extraction). Freshly spiked Cu-salt was the most toxic for reproductive output of the worms, followed by Cu-NPs and then Cu-field. XANES indicated only one oxidation state (II) in Cu-salt and Cu-field soil, whereas in Cu-NPs soil it was present in all oxidation states (0, I and II). The partial oxidation of the Cu-NPs (in soil) was evident and with limited dissolution.

The effects of several copper (Cu) and silver (Ag) nanomaterials were assessed using the cellular energy allocation (CEA), a methodology used to evaluate the energetic status and which relates with organisms’ overall condition and response to toxic stress. Enchytraeus crypticus (Oligochatea), was exposed to the reproduction effect concentrations EC20/50 of several Cu and Ag materials (CuNO3, Cu-Field, Cu-Nwires and Cu-NPs; AgNO3, Ag NM300K, Ag-NPs Non-coated and Ag-NPs PVP-coated) for 7 days (0-3-7d). The parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption (Ec) integrated to obtain the CEA. Results showed that these parameters allowed a clear discrimination between Cu and Ag, but less clearly within each of the various materials. For Cu there was an increase in Ec and protein budget, while for Ag a decrease was observed. The results corroborate known mechanisms, e.g., with Cu causing an increase in metabolic rate whereas Ag induces mitochondrial damage. The various Cu forms seem to activate different mechanisms with size and shape (e.g., Cu-NPs versus Cu-Nwires), causing clearly different effects. For Ag, results are in line with a slower oxidation rate of Ag-NMs in comparison with Ag-salt and hence delayed effects.