Study on the Elemental Composition of Environmental Nanoparticles Separated in a Rotating Coiled Column: How Hazardous May Be Urban Dust and Volcanic Ash

Study on the elemental composition of nanoparticles is of great importance due to their high mobility in the environment and ability to penetrate into human organism. A global aspect is the transport of nutrient and toxic elements with environmental nanoparticles, which can serve as a carrier for these elements. Nanoparticles in complex polydisperse environmental samples such as dust, volcanic ash, or soil may represent only about thousandths or less of bulk sample. Therefore, their recovery followed by quantitative determination of analytes is a difficult task. A novel technique, sedimentation field-flow fractionation in a rotating coiled column, was applied to the fractionation of urban dust and volcanic ash samples with water being used as a carrier fluid. nanoand submicron particles have been separated, weighted, characterized by electronic microscopy and static laser light scattering, and then quantitatively analyzed by ICP-AES and ICP-MS (after digestion). In urban street dust samples, the elements that may be of anthropogenic origin (Zn, Cr, Ni, Cu, Cd, Sn, Pb) were found to concentrate mainly in <0.3 and 0.3-1 μm fractions. It has been shown that the concentrations of Cr, Ni, Zn, Pb, Sn in the finest fraction (<0.3 μm) of street dust can be one order of magnitude higher than the concentrations of elements in bulk sample and coarse fractions. For volcanic ash samples, it has been evaluated that nanoparticles may concentrate potentially toxic elements of volcanic gases. The concentrations of Zn, Cu, Pb, Tl, Bi, Sn, As, Sb in the size fraction <0.2 μm can be two orders of magnitude higher than the concentrations of these elements in bulk sample. Hence, measuring the total concentrations of elements in dust and ash leads to underestimation of the hazard of these samples. The proposed approach to the separation and quantitative analysis of environmental nanoparticles can be a powerful tool for risk assessment related to toxic elements in dust, ash, and other particulate matter.