Impact of Silver Nanoparticles on the Aqueous Environment: Analytical Method Development and Field Experiments

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The research objective of the proposed project is the investigation of the impact of silver nanoparticles from consumer products and potential reaction products on the aqueous environment. The study will include the development of a range of adequate analytical methods and their application in laboratory and field experiments. The goals are:1. The adaption and optimization of analytical methods and sampling strategies for the examination of dissolved and nanoparticulate silver in wastewater and surface waters. 2. The employment of the developed methods in laboratory and field experiments to answer the following questions:- How much silver nanoparticles and other silver species are removed during wastewater treatment?- How does silver nanoparticles distribute in surface water after release from the sewage plant? - In which species is silver present? Do transformations take place in the aqueous environment?In part 1 of the project, diverse analytical methods such as isotope dilution analysis, isotope fractionation analysis, single particle ICP-MS, and cloud point extraction shall be developed for the identification and quantification of silver species, including silver ions Ag(I) and silver nanoparticles. The developed methods shall be robust and adequate for the analysis of environmental samples such as lake water and sediment. In part 2 of the project, the behaviour of silver nanoparticles in sewage treatment plants will be investigated by balancing of silver input and output of a respective plant. Speciation of influent and effluent samples will show if species transformation takes place during sewage treatment. The behaviour of the silver nanoparticles towards dissolution, oxidation, precipitation, as well as their interaction with organic matter (humic acids) will be assessed. Species transformation shall be monitored by a range of analytical methods developed in part 1. In order to assess the impact of silver nanoparticles on the aqueous environment, a whole lake addition study will be carried out in the Experimental Lake Area in Ontario, Canada. Nanoparticles will be added into an experimental lake as a point source. The lake will be sampled directly and after total mixing of the lake water. The lake water and the sediment samples will be analysed by means of the methods developed in part 1 of the project. The results will give information about distribution in the lake, as well as species information. A comparison with the results of the laboratory experiments regarding their behaviour during dissolution, precipitation, oxidation, etc. will allow an extensive assessment of the impact of silver nanoparticles on the aqueous environment.