Dissolution of Selected Trace Elements from Simulated Atmospheric Aerosol Aging and Human Exposure of Mineral Dust and Coal Fly Ash

Abstract

Atmospheric particles from natural and anthropogenic sources contain reactive trace elements (TE) of importance to aerosol multiphase chemistry, health risk assessment of inhalation and ingestion, and ocean productivity. While the dissolution of TE from model and field-collected particles in various aqueous phase conditions of relevance to aerosol liquid water and bodily fluids have received attention, there remain knowledge gaps on (a) benchmark materials and methods for standardizing dissolution experiments and (b) the relevance of dissolution time scales in previously published reports to real-time, long range transport and human exposure. Here, we use fully characterized reference solid materials, namely, Arizona test dust (AZTD) and combustion coal fly ash samples from India, the U.S., and Europe, representative of atmospheric aerosol particles from natural and combustion sources. Using ICP-MS and optimized analytical procedures that address technical challenges with selectivity and sensitivity, we quantified the concentrations of dissolved TE Fe, Cu, Mn, As, and Pb under simulated atmospheric aging (14 days) and human exposure experiments using saliva (5 min), lung fluid (10 min), and gastric juice (1 h). We found that levels of dissolved TE normalized to the total dissolvable levels under strong acid extraction are much higher in simulated aged aerosol water than in bodily fluids of unreacted particles. The significance of these results is discussed in the context of aerosol multiphase chemistry, health impacts, and ocean biogeochemistry.