Copper toxicity

Copper toxicity (or Copperiedus) is a type of metal poisoning caused by an excess of copper in the body. Copperiedus could occur from consuming excess copper salts, but most commonly it is the result of the genetic condition Wilson's disease and Menke's disease, which are associated with mismanaged transport and storage of copper ions. Copper is essential to human health as it is a component of many proteins. But hypercupremia (high copper level in the blood) can lead to copper toxicity if it persists and rises high enough. Chronic toxicity by copper is rare. The suggested safe level of copper in drinking water for humans varies depending on the source, but tends to be pegged at 1.3 mg/L. So low is the toxicity of copper that copper(II) sulfate is a routine reagent in undergraduate chemistry laboratories. Signs and symptoms Acute symptoms of copper poisoning by ingestion include vomiting, hematemesis (vomiting of blood), hypotension (low blood pressure), melena (blac

Species-species interactions modulate copper toxicity under different visible light conditions

Valérie Gagnaux

Combination of biotic and abiotic factors influences the effects of naturally occurring or anthropogenic chemicals on photosynthetic microorganisms in the aquatic environment. Nonetheless, the combined effects of physical stressors and species-species interaction on chemicals toxicity are still poorly understood. The present study examines the responses of the green alga Chlamydomonas reinhardtii and the cyanobacterium Synechocystis sp. alone and in mixtures to copper exposure under increasing visible light intensities. Cell growth, chlorophyll bleaching, oxidative stress and membrane permeability were determined by flow cytometry in both mono- and multi-species tests. The results revealed that species-species interactions influenced copper toxicity under different light regimes at 4 h and 48 h - exposure. For a given light condition, monocultures of Synechocystis sp. were more sensitive to copper than those of C. reinhardtii. In long-term incubation C. reinhardtii sensitivity to copper diminished in presence of Synechocystis sp. under low-intensity light, however it was enhanced under high-intensity light. The present results revealed the complex interplay between visible light intensity variations, species-species interaction and copper effects to phytoplankton in long- term exposure.

ACADEMIC PRESS INC ELSEVIER SCIENCE2019

Investigation of the Electrochemical Destruction of X-ray Contrast Media using Boron-‐Doped Diamond Electrodes (BDD)

Guillaume Tissot

Iodinated X-ray contrast media (ICM) are persistent micropollutants in wastewater, which come mainly from hospital activities. Currently, there is no efficient method of treatment for this class of compounds, which leads to their increased presence in surface water and drinking water. In this work we propose to treat directly ICM in urine, meaning at high concentration, by electrochemical oxidation process using BDD electrodes. In a first step of the project, determination of the reactivity of Iohexol towards electrochemical oxidation in inactive electrolyte was performed. In subsequent iohexol electrolysis experiment the electrolyte composition was gradually modified until electrolysis of Iohexol in fresh urine. Obtained results were compared with those predicted by adjusted kinetic model of COD elimination. Model is based on the kinetic of the electrochemical oxidation is controlled by diffusion, and it was demonstrated, in this work, that this is also the case for the electrochemical oxidation of Iohexol. This methodology permits to determine interference that urine components such as chloride and ammonia have on the electrochemical oxidation. The obtained results showed that 99% of Iohexol present in the electrolyte and at least 85% of the initial COD elimination can be achieved with an efficiency close to 100%, even in fresh urine. Investigation of the main constituents of urine showed that chloride has a positive effect on the process efficiency due to both catalytic and no‐catalytic action (oxidation of organics compounds, via electrogenereted active chlorine, close to the electrode or in the bulk). On the contrary ammonia has no effect on the efficiency if it is present alone, and negative effect if chloride is also present (certainly due to chloramine formation). Nevertheless, at high concentration of ICM, the effect of chloride and ammonia is negligible as experiment in fresh urine demonstrated. As expected, the reaction of hydroxyl radical with Iohexol is non-specific. Preliminary identifications of transformation products by UPLC-MS showed that electrochemical oxidation can lead to nucleus attack (deiodination) or side chain attack unselectively. In addition, deiodination by cathodic reduction under mass transfer control is also possible according to these UPLC‐MS results, and by the kinetic of Iohexol elimination. At an elimination of 85% COD in treated urine only a very low concentration of pollutant remain. Ecotoxicity and biodegradability analyses were performed with the treated urine at this point. Toxicity assays showed some ecological toxicity towards environment; biodegradability test didn’t show clear biodegradation. Finally, operating cost analysis for a possible installation using electrochemical oxidation process with BDD electrodes showed that even if other advanced oxidation process (AOPs), such as processes such as ozonation or UV/H2O2, demonstrate the same efficiency as electrochemical oxidation in the future, electrochemical oxydation using BDD electrode remains strongly competitive economically.

2012

Etude du cycle biogéochimique du cuivre et du cadmium dans deux écosystèmes forestiers

Catherine Keller

The biogeochemical cycle of copper and cadmium has been studied in two forested ecosystems for two years. These two sites are: a) a Norway spruce forest (Picea abies) on an acid brown soil (FAQ: Dystric cambisol) and b) a mixed coniferous forest (Picea abies, Pinus cembra, Larix decidua and Abies alba) on a podzol. Both of them are located on low heavy metal polluted sites: the Swiss Plateau (850 m a.s.l.) for the first one and the oriental edge of the Mont-Blanc Massif (1650 m a.s.l.) for the second one. The Cu and Cd stocks in the vegetation and in the soil are evaluated. Heavy metal fluxes through the ecosystems are determined by analysis of concentrations and quantities of rain, throughfalls, stemflows, lysimetric soil solution and litterfall. In addition, the forms of Cu and Cd immobilization in soils are studied by means of sequential extraction, whereas immobilization forms in solution are studied by means of ion exchange chromatography and selective electrode. The results obtained allowed us to draw conclusions concerning the general pollution level in the experimental sites and the annual and/or detailed behaviour of Cu and Cd in the ecosystems. The conclusions are the following: As expected, the sites are not polluted since concentrations and fluxes are low. The chemical composition of solutions is modified during transition through the ecosystem, especially the copper concentrations. The acid brown soil humic layer is more efficient than the podzol humic layer in modifying this composition. There is no significant seasonal variation of concentrations and fluxes. However, the metal diffusion through the ecosystem is almost immediate. The soil plays an essential role in the immobilization of the heavy metals. The organic and organo-mineral layers are particularly active in this process. Exportations out of the ecosystems are limited. They are relatively more important for the podzol than for the acid brown soil and higher for Cd than for Cu. Transfer and stocking forms, and the ways of input to the soil depend on the metal considered: Copper input to the soil is mainly due to litterfall. In the soil, the metal has a preference to be associated with organic matter. In solution, it forms complexes with dissolved organic matter (mainly fulvic acid of MW < 1000 dalton). So, it is strongly retained within the soil and it cannot be easily drained out of the soil profile. At the opposite, cadmium is mostly transported by liquid means (throughfalls). In solution, it is present as free cadmium ions. In the soil, it is less strongly fixed than Cu since Cd is mostly associated with Fe and Mn oxides. For both of the metals, the free ion concentration in solution depends on pH and the saturation rate of organic matter. The latter has a heterogenous and polyfunctional character which explains a similar complexing capacity for all the samples studied. The differences observed in copper and cadmium behaviour can explain the variable diffusion of a polluting Cu and Cd flux through a given ecosystem and to the aquifer. The soil intervenes as a discriminating factor when the two experimental sites are compared.

EPFL1991

Etude du cycle biogéochimique du cuivre et du cadmium dans deux écosystèmes forestiers

Catherine Keller

EPFL1991

Investigation of the Electrochemical Destruction of X-ray Contrast Media using Boron-‐Doped Diamond Electrodes (BDD)

Guillaume Tissot

2012

Species-species interactions modulate copper toxicity under different visible light conditions

Investigation of the Electrochemical Destruction of X-­ray Contrast Media using Boron-­‐Doped Diamond Electrodes (BDD)

Etude du cycle biogéochimique du cuivre et du cadmium dans deux écosystèmes forestiers

Species-species interactions modulate copper toxicity under different visible light conditions

Etude du cycle biogéochimique du cuivre et du cadmium dans deux écosystèmes forestiers

Investigation of the Electrochemical Destruction of X-­ray Contrast Media using Boron-­‐Doped Diamond Electrodes (BDD)

Investigation of the Electrochemical Destruction of X-ray Contrast Media using Boron-‐Doped Diamond Electrodes (BDD)

Investigation of the Electrochemical Destruction of X-ray Contrast Media using Boron-‐Doped Diamond Electrodes (BDD)