Studies of Particulate Matter in Diverse Regions with a Focus on Size and Composition

Abstract

Particulate matter can influence public health, climate, and atmospheric processes. The size and composition of aerosol particles must be characterized to assess their impact in diverse regions. To address this, studies were performed in the following regions: Marina, California; Hayden, Arizona; Tucson, Arizona; Mt. Lemmon, Arizona; Manila, Philippines; Mesa Verde, Colorado; Northeast Pacific; Northwest Atlantic. These studies used multiple data types including ground, airborne, reanalysis, airmass back-trajectory, and meteorology. Size-resolved measurements from a micro-orifice uniform deposit impactor were used in Marina, Hayden, Tucson, Mt. Lemmon, and Manila to examine mass size distributions and crustal enrichment factors (EFs) of arsenic, cadmium, and lead. Each region represented a different type of environment: coastal marine (Marina), arid mining facility, (Hayden), arid urban (Tucson), free troposphere (Mt. Lemmon), and coastal urban (Manila). Marina and Manila were influenced by biomass burning which allowed for comparisons between fire and non-fire data. Manila data was collected over a 16-month period which allowed for seasonal analysis. Mass size distribution analysis showed bimodal profile in submicrometer and supermicrometer diameter range. The exception was Manila, which did not have a peak in the submicrometer range. EF analysis showed dust at all sites particularly in the submicrometer range. For Mesa Verde, Colorado, Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring data were used to examine particulate matter (PM2.5 and PM10) extreme events between 1989 and 2018. Extreme events were assigned as any day with a PM2.5 level above 90th percentile value of PM2.5 for each month based on the full duration of the dataset. Meteorological data were used to obtain information about different environmental parameters to provide environmental context for the study region. Airmass back-trajectory data were used to provide insight into the source regions for extreme event days. The sources of the extreme events were found with the Navy Aerosol Analysis and Prediction (NAAPS) aerosol model. Four sources were used in the classification: Asian dust, non-Asian dust, smoke, and “other.” The weekly, monthly, and interannual trends in the number of extreme events was assessed. There were no notable weekly trends. Monthly trends show that winter months were dominated by “other” sources while spring months had more dust events. Interannual trends showed that dust and smoke events were more prominent than “other” events in more recent years. Airborne field data from the MONterey Aerosol Research Campaign (MONARC: Northeast Pacific - summer 2019) and Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE: Northwest Atlantic – winter and summer 2020) were used to focus on the relationship between giant cloud condensation nuclei (GCCN) and clouds. Measurements from cloud water composition data and particle number concentration from wing-mounted optical probes at different minimum dry diameters thresholds above and below boundary layer clouds were used to better understand this relationship. GCCN-cloud interactions were impacted by cloud water sea-salt concentrations (not dust), region, dry diameter threshold of GCCN, and environmental parameters such as sub-cloud turbulence and winds.