Changes in oxidative potential of soil and fly ash after reaction with gaseous nitric acid. (January 2018)

• Record Type: Journal Article
• Authors: Zhan, Ying; Ginder-Vogel, Matthew; Shafer, Martin M.; Rudich, Yinon; Pardo, Michal; Katra, Itzhak; Katoshevski, David; Schauer, James J.
• Is Part Of: Atmospheric environment. Volume 173(2018)
• Page Start: 306
• Page End: 315
• Publication Date: 2018-01
• Subjects: Acid aging -- Mineral dust -- ROS activity -- Metals; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2017.11.008
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: The goal of this study was to examine the impact of simulated atmospheric aging on the oxidative potential of inorganic aerosols comprised primarily of crustal materials. Four soil samples and one coal fly ash sample were artificially aged in the laboratory through exposure to the vapor from 15.8 M nitric acid solution for 24 h at room temperature. Native and acid-aged samples were analyzed with a cellular macrophage and acellular dithionthreitol assays to determine oxidative potential. Additionally, the samples were analyzed to determine the concentration of 50 elements, both total and the water-soluble fraction of these elements by Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICMS) and crystalline mineral composition using X-ray Diffraction (XRD). The results show that reactions with gaseous nitric acid increase the water-soluble fraction of many elements, including calcium, iron, magnesium, zinc, and lead. The mineral composition analysis documented that calcium-rich minerals present in the soils (e.g., calcite) are converted into different chemical forms, such as calcium nitrate (Ca(NO3 )2 ). The nitric acid aging process, which can occur in the atmosphere, leads to a 200–600% increase in oxidative potential, as measured by cellular and acellular assays. This laboratory study demonstrates that the toxic effects of aged versus freshly emitted atmospheric dust may be quite different. In addition, the results suggest that mineralogical analysis of atmospheric dust may be useful in understanding its degree of aging. Highlights: Nitric acid aging increases elements' water-soluble fraction. Calcium-rich minerals are converted into different chemical forms by nitric acid The nitric acid aging process leads to a 200-600% increase in oxidative potential