Effect of metal speciation on the oxidative potential and cytotoxicity of airborne particles

Abstract

<p>Aerosol particle components can mix and interact with oxidants and organic compounds present in the atmosphere. How these chemical components interact and how the interactions affect the Earth’s climate, particle toxicity and human health is largely unknown. In the case of trace metals, the main focus so far has been the determination of the total amount while much less attention has been directed towards the metal speciation. Aqueous phase processing of aerosol can lead to substantial modifications of aerosol chemical and physical properties [1] by promoting the formation of metal-organic ligand complexes in atmospheric aqueous phases, like fog/cloud droplets and deliquescent aerosol. Such process can increase the solubility of metals, therefore their bioavailability [2], and affect their capability to generate reactive oxygen species.</p><p>We investigated the formation of metal-organic ligand complexes, especially those involving small dicarboxylic acids, in urban aerosol collected in the city centre of Padua (Italy), in the Po Valley. We assessed the effects of metal-ligand complexes formation on the solubility and solubilisation kinetic of metals from the particles to aqueous solutions simulating fog/cloud water. We found that solubilisation kinetics of many metals depended on the chemical form in which they were present in the aerosol and they were influenced by the environmental conditions during the campaign. Changes in oxidative potential (OP) and cytotoxicity of particles due to the formation of metal-ligand complexes were investigated by performing acellular and cellular in vitro tests, respectively. Preliminary results showed that metals and their complexed forms are both characterized by different OP and cellular toxicity.</p><p> </p><p>References</p><p>[1] Decesari, S., Sowlat, M. H., Hasheminassab, S., Sandrini, S., Gilardoni, S., Facchini, M. C., Fuzzi, S., and Sioutas, C. Atmos. Chem. Phys., <strong>17</strong>, 7721‑7731 (2017).</p><p>[2] Okochi, H., and Brimblecombe, P. Sci. World J., <strong>2</strong>, 767–786(2002).</p>