Elemental PM10 Compositions Associated with Dust Events around the Great Salt Lake

Interest in the chemical and elemental compositions of the dusts of the Great Salt Lake (GSL), and its potential impacts on local populations, has been an area of growing interest as the areal extent of the lake has shrunk and more playa has been exposed. Additionally, a bulk of the elevated exposures are expected to adversely impact populations identified as having significant Environmental Justice (EJ) concerns by the USEPA’s EJ Screening Tool. The Utah Division of Air Quality’s (UDAQ’s) routine collection of PM₁₀ samples at several locations across their network provides a convenient opportunity to assess potential impact of wind-blown GSL dust elemental speciation at sites targeted to represent exposed populations. Recently, investigators at Utah State University’s (USU’s) Utah Water Research Laboratory (UWRL) were granted access to eight filters from two different locations, Hawthorne (HW) and the Tech Center (UC), for two high dust periods (Apr. 19^th and 21^st, 2022) and two low, or suspected non-impacted, dust days (Apr. 23^rd and 24^th, 2022). At the UWRL’s Environmental Quality Laboratory (EQL), the TFE filters were digested in a nitric acid solution and quantified for target elements via inductively coupled plasma mass spectrometry (ICP-MS). The target analytes included beryllium (Be), sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), potassium (K), calcium (Ca), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), strontium (Sr), cadmium (Cd), antimony (Sb), barium (Ba), thallium (Tl), and lead (Pb). The elements of particular and historical interest in relation to the GSL dusts include As, Se, Cd, and Pb. Seven elements (Ca, Si, Mg, Al, Na, Fe, K) generally made up 1-10% each of PM₁₀ mass during and outside of dust events with most of the other target elements present in most samples. During dust events only Mg, Ca, V, and Sr consistently enriched above “background” or non-dust events. However, owing to above average increased PM₁₀ concentrations, the potentially inhaled mass for most elements greatly increased (≥10x) during the dust events. The wet winter of 2023 along the northern Wasatch Front allowed for the GSL to regain some surface elevation and reclaim some of the drying playa in the Spring of 2023. However, several dust events were once again observed and PM₁₀ samples collected as part of the regulatory network were obtained for additional compositional analysis. This latest data set include two high PM₁₀ days, two moderate, and two non-impacted “background” days. These filters are currently being analyzed via X-ray Fluorescence (XRF) and the results will be discussed and compared to the 2022 data along with relevant meteorology and spatial location relative to the GSL playa and impacted populations.