Controls on the chemical composition of saline surface crusts and emitted dust from a wet playa in the Mojave Desert (USA)

Abstract

Saline-surface crusts and their compositions at ephemeral, dry, and drying lakes are important products of arid-land processes. Detailed understanding is lacking, however, about interactions among locally variable hydrogeologic conditions, compositional control of groundwater on vadose zone and surface salts, and dust composition. Chemical and physical data from groundwater, sediments, and salts reveal compositional controls on saline-surface crusts across a wet playa, Mojave Desert, with bearing on similar settings elsewhere. The compositions of chemically and isotopically distinctive shallow (<3 m) water masses are recorded in the composition of associated salts. In areas with deeper and more saline groundwater, however, not all ions are transported through the vadose zone. Retention of arsenic and other elements in the vadose zone diminishes the concentrations of potentially toxic elements in surface salts, but creates a reservoir of these elements that may be brought to the surface during wetter conditions or by human disturbance. Selective wind-erosion loss of sulfate salts was identified by the compositional contrast between surface salt crusts and underlying groundwater. At the sub-basin scale, compositional links exist among groundwater, salt crusts, and dust from wet playas. Across the study basin, however, lateral variations in groundwater and solid-salt compositions are produced by hydrogeologic heterogeneity.

Wind erosion and dust from US drylands: a review of causes, consequences, and solutions in a changing world

“…Further, dry or ephemeral lakes, common in the Great Basin and Mojave Deserts, produce very fine dust that contain elevated levels of potentially toxic inorganic constituents (Goldstein et al. ).…”

“…Increases in regional dust forecast with increasing aridity in the southwest are expected to further impact human health, including increasing rates of Coccidiomycosis and up to a 300% increase in hospital admissions for cardiovascular and respiratory illness (adults ≥65 yr old based on RCP8.5 emission scenarios; Achakulwisut et al 2018). Further, dry or ephemeral lakes, common in the Great Basin and Mojave Deserts, produce very fine dust that contain elevated levels of potentially toxic inorganic constituents (Goldstein et al 2017).…”

Macroscale salt-crust formation on indoor playa-like test plots for dust-emission research applications : methodology assessment

“…A brackish solution of water (henceforth referred to as saltwater), 5 g/L sodium chloride (NaCl), 2 g/L calcium chloride (CaCl2), 2 g/L magnesium sulfate (MgSO4), and 1 g/L sodium bicarbonate (NaHCO3) was mixed using a mortar mixing drill attachment and added to the plots through gravity feed and misting on a daily basis, Monday through Friday, over the course of 8 weeks. This particular salt mixture was chosen to maximize the likelihood of recrystallization through evaporation and was based on playa surface-soil compositions reported in published literature (e.g., Rosen 1994;Reynolds et al 2007;Goldstein et al 2011Goldstein et al , 2017). The mixing ratios described above are for dehydrated versions of CaCl2 and MgSO4.…”

Unseen Dust Emission and Global Dust Abundance: Documenting Dust Emission from the Mojave Desert (USA) by Daily Remote Camera Imagery and Wind‐Erosion Measurements

“…In its geomorphology and surficial sediment, the Soda Lake basin is similar to many other dry-lake and associated alluvial settings known to emit dust in the Mojave Desert (Gill, 1995;Goldstein et al, 2017;Redmond, 2009;Reheis, 2006;Reheis & Kihl, 1995;Reheis et al, 2002;Reheis & Urban, 2011;Reynolds et al, 2007Sweeney et al, 2011). About 287 such basin-type settings encompassing about 3,800 km 2 have been mapped (D. Bedford and D. Miller, U.S. Geological Survey, personal communication).…”