TRACING OF ENGINEERED METAL AND OXIDE NANOPARTICLES IN SOIL AND EARTHWORMS USING NEUTRON ACTIVATION

摘要

One of the major uncertainties concerning the possible dangers that engineered nanoparticles (ENPs) may represent for the environment is to which extent they will be transferred from water, sediments and soil to living organisms (Wiesner et al., 2006) Research on the environmental impact of engineered nanoparticles (ENPs) is hampered by a lack of tools to trace particle movement and transfer (Gulson and Wong 2006). This is particularly true when studying behavior in dirty matrices like soils and sediments (Biswas and Wu, 2005). We have developed and implemented a method for labeling metal and oxide ENPs using neutron activation that seems very useful in this respect. Neutron activation implies irradiation of ENPs with a radioactive neutron source and the consequent formation of radioactive isotopes within the irradiated ENPs Depending on the element in question, the ENPs becomes more or less radioactive and can be traced and quantified by gamma or beta scintillation counting. Specimens of biological materials (whole or dissected organisms) may also be subjected to autoradiographical imaging as to permit localization of ENPs within tissues or organs We here describe the prerequisites for neutron activation and the facility of using the resulting ENPs in laboratory experiments. We also present results on uptake metabolism and sequestration of ENPs within the bodies of earthworms (Eisenia fetida) subjected to ENP uptake in a feeding experiment with cobalt nanoparticles. Finally results on mobility and sequestration of Ag and Co ENPs in soils and their preferential association with organic matter and clay will be presented.