The Role of Hydrates, Competing Chemical Constituents, and Surface Composition on ClNO₂Formation

Authors

Haley M. Royer, Rosenstiel School of Marine and Atmospheric Science
Dhruv Mitroo, Rosenstiel School of Marine and Atmospheric Science
Sarah M. Hayes, United States Geological Survey
Savannah M. Haas, University of Michigan, Ann Arbor
Kerri A. Pratt, University of Michigan, Ann Arbor
Patricia L. Blackwelder, University of MiamiFollow
Thomas E. Gill, The University of Texas at El Paso
Cassandra J. Gaston, Rosenstiel School of Marine and Atmospheric Science

Document Type

Article

Publication Title

Environmental Science and Technology

ISSN

0013936X

Publication Date

1-1-2021

Keywords

aerosol, air quality, dinitrogen pentoxide, halogen, heterogeneous reaction, hygroscopicity, mineral dust, nitryl chloride

Abstract

Atomic chlorine (Cl^•) affects air quality and atmospheric oxidizing capacity. Nitryl chloride (ClNO₂)- A common Cl^• source-forms when chloride-containing aerosols react with dinitrogen pentoxide (N₂O₅). A recent study showed that saline lakebed (playa) dust is an inland source of particulate chloride (Cl-) that generates high ClNO₂. However, the underlying physiochemical factors responsible for observed yields are poorly understood. To elucidate these controlling factors, we utilized single particle and bulk techniques to determine the chemical composition and mineralogy of playa sediment and dust samples from the southwest United States. Single particle analysis shows trace highly hygroscopic magnesium and calcium Cl-containing minerals are present and likely facilitate ClNO₂ formation at low humidity. Single particle and mineralogical analysis detected playa sediment organic matter that hinders N₂O₅ uptake as well as 10 Å-clay minerals (e.g., Illite) that compete with water and chloride for N₂O₅. Finally, we show that the composition of the aerosol surface, rather than the bulk, is critical in ClNO₂ formation. These findings underscore the importance of mixing state, competing reactions, and surface chemistry on N₂O₅ uptake and ClNO₂ yield for playa dusts and, likely, other aerosol systems. Therefore, consideration of particle surface composition is necessary to improve ClNO₂ and air quality modeling.

DOI

10.1021/acs.est.0c06067

Volume

55

Issue

5

First Page

2869

Last Page

2877

NSUWorks Citation

Haley M. Royer, Dhruv Mitroo, Sarah M. Hayes, Savannah M. Haas, Kerri A. Pratt, Patricia L. Blackwelder, Thomas E. Gill, and Cassandra J. Gaston. 2021. The Role of Hydrates, Competing Chemical Constituents, and Surface Composition on ClNO₂Formation .Environmental Science and Technology , (5) : 2869 -2877. https://nsuworks.nova.edu/occ_facarticles/1154.