The Effect of a Receding Saline Lake (The Salton Sea) on Airborne Particulate Matter Composition

Abstract

The composition of ambient particulate matter (PM) and its sources were investigated at the Salton Sea, a shrinking saline lake in California. To investigate the influence of playa exposure on PM composition, PM samples were collected during two seasons and at two sites around the Salton Sea. To characterize source composition, soil samples were collected from local playa and desert surfaces. PM and soil samples were analyzed for 15 elements using mass spectrometry and X-ray diffraction. The contribution of sources to PM mass and composition was investigated using Al-referenced enrichment factors (EFs) and source factors resolved from positive matrix factorization (PMF). Playa soils were found to be significantly enriched in Ca, Na, and Se relative to desert soils. PMF analysis resolved the PM data with four source factors, identified as Playa-like, Desert-like, Ca-rich, and Se. Playa-like and desert-like sources were estimated to contribute to a daily average of 8.9% and 45% of PM mass, respectively. Additionally, playa sources were estimated to contribute to 38-68% of PM Na. PM Se concentrations showed strong seasonal variations, suggesting a seasonal cycle of Se volatilization and recondensation. These results support the importance of playas as a source of PM mass and a controlling factor of PM composition.

Analyses of Namibian Seasonal Salt Pan Crust Dynamics and Climatic Drivers Using Landsat 8 Time-Series and Ground Data

“…Such salt pan environments have been recognized as a significant sources of mineral dust in arid regions [5,6]. The importance of their dust emissions is illustrated in studies from the western United States [7,8], Australia [9,10], central Asia [11,12], as well as north-central and southern Africa [13][14][15][16][17]. The compositions of dust from these sources can have effects on the climate [18], the degradation of groundwater [19], soil and ocean fertilization [20], as well as human [21] and ecosystem health [22].…”

Spatial Particulate Fields during High Winds in the Imperial Valley, California

“…They found that the filters were dominated by large crustal particles up to 30 µm in diameter that matched local soils, and that windblown dust was a major source on high PM days. Windblown dust in the area has also been extensively investigated with respect to the increasing importance of dust emissions from exposed beds of the Salton Sea, which bounds the valley to the north [13][14][15][16][17][18]. Windblown dust events also lead to PM10 regulatory exceedances in the air basin [19].…”

Downslope Winds and Dust Storms in the Salton Basin

“…From this same study, and assuming no systematic changes in water input to the Salton Sea, the estimated rate of additional playa exposure over the next five years (2018-2023) will be 5,500 acres per year, and that by 2045, when the Sea level stabilizes, there will be a total increase of 105,000 acres of exposed playa, also relative to 2003. This exposure of dry lakebed surfaces to the atmosphere may alter the composition of particular matter in the region (Frie et al 2017), and increase dust emission from the playa, although the only study of this effect was inconclusive (Parajuli and Zender 2018). The floor of the Salton Basin consists of a layer of wet alluvial deposits that is thousands of feet deep (USDI/CRA 1974), and pesticide-laden runoff from agriculture has been a major source of freshwater input to the Salton Sea over the last 100 years (Schroeder et al 2002).…”

“…The floor of the Salton Basin consists of a layer of wet alluvial deposits that is thousands of feet deep (USDI/CRA 1974), and pesticide-laden runoff from agriculture has been a major source of freshwater input to the Salton Sea over the last 100 years (Schroeder et al 2002). Thus, not only is newly exposed playa erodible (Buck et al 2011;Sweeney et al 2011), but this soil could contain high levels of toxic material (Frie et al 2017).…”