FORURENS: Development of methods for tracing nanoparticles in the environment

There is considerable uncertainty related to the potential hazards of nanoparticles (NPs) into the environment, and public concern following reports of toxic effects. One of the major challenges in studying NPs is to detect their presence and distinguish them from natural particles and amorphous materials present in environmental media. The project proposes the development and application of three methods to aid this detection and characterisation. First, we will use neutron activation (NA) to provide ra dio-labelled NPs. This will enable studies of the interaction of NPs with environmental media, bioavailabilty, metabolism and internal distribution in organisms. Our group has already carried out successful pilot studies using Co3O4, CeO2 and Ag NPs. Sec ond, we will use electron microscopy (EM) techniques to study the localisation of stable and radioactive NP in biological samples at a um scale (NPs are likely to aggregate and thus be detectable at this scale). This permits the quantification of exposure and identification of the organs at risk, factors that are crucial for dose-response assessments and ecotoxicology studies. Third, we will use synchrotron radiation to study speciation (oxidation state, binding). Nanometer resolution can be achieved usi ng the Nano facility at ERSF. Knowledge on NP speciation is vital for toxicity and mobility assessment. Our hypothesis is that change of oxidation state in vivo can cause biological damage (e.g. by the production of reactive oxygen species). Finally, the applicability of the methods will be demonstrated in studies on sorption in soil, sediment-water partitioning, speciation in water, biological uptake, metabolism and excretion (earthworms, fish). The outputs of the project will be documentation of method applicability for different NPs, flux recommendation for activation, detection limits, etc., together with data on mobility and uptake. Such data are urgently required to perform ecological risk assessment.