Competing droughts affect dust delivery to Sierra Nevada

Abstract

The generation and transport of mineral dust is strongly related to climate on seasonal, year-to-year, and glacialinterglacial timescales. The modern dust cycle is influenced by soil moisture, which is partly a function of drought duration and severity. The production and transport of dust can therefore be amplified by global and regional droughts, thereby moderating ecosystem vulnerability to disturbance through the influence of dust on nutrient delivery to ecosystems. In this work, we use strontium and neodymium isotopes in combination with trace element concentrations in modern dust samples collected in 2015 to quantify the role of regionally versus globally supplied dust in nutrient delivery to a montane ecosystem. The study sites lie along an elevational transect in the southern Sierra Nevada, USA, with samples spanning the dry seasons of 2014 (Aciego et al., 2017) and 2015 (this study), when the region was experiencing a historic drought. The goal of our research was to quantify the spatial and temporal variability and sensitivity of the dust cycle to short term changes at nutrientlimited sites. We find that, during the dry season of 2015, Asian sources contributed between 10 and 40% of dust to sites located along this elevational transect, and importantly increased in importance during the summer growing season compared to regional dust sources. These changes are likely related to the prolonged drought in Asia in 2015, highlighting both the sensitivity of dust production and transport to drought and the teleconnections of dust transport in terrestrial ecosystems.

Phosphorus Speciation in Atmospherically Deposited Particulate Matter and Implications for Terrestrial Ecosystem Productivity

“…At two high-elevation CA-SSCZO sites, it was estimated that about 10−20% of PM input in July was derived from Asia, whereas about 20−40% was Asian-sourced in October. 50 In the Great Basin and Colorado Plateau, regional PM sources are generally to the west-southwest, while trans-Pacific air masses often move in from the west-northwest, to episodically supply PM from a mixture of sources. 34,36,37 Prior studies estimated that, on average annually, about one-third of the PM deposited in the western U.S. is sourced from the Asian continent, although inputs are spatially and temporally variable.…”

Impacts of climate and disturbance on nutrient fluxes and stoichiometry in mixed-conifer forests

“…In a previous study at the Kings River basin, net release of total P from the regolith was estimated to be ten times higher than losses of dissolved P from stream export (Uhlig et al 2017). However, the bedrock P input can be outpaced by dust deposition of P, at least during drought (Aciego et al 2017;Aarons et al 2019). Thus, measurements of P input through bedrock weathering and dust deposition are both important for studying forest P cycle given increased drought events under rising temperatures.…”

Dust‐Drought Nexus in the Southwestern United States: A Proxy‐Model Comparison Approach

“…The inferred connection (i.e., nexus) between dust and drought is common for North America (Aarons et al, 2019;Achakulwisut et al, 2017Achakulwisut et al, , 2018Zender & Kwon, 2005), strengthened by research on the Dust Bowl (e.g., Bolles et al, 2017;Cook et al, 2008;Schubert et al, 2004) and on its cultural depiction as barren landscapes and extreme dust storms (McLeman et al, 2014). However, a review of the literature in fact reveals a continuum in the strength of the dust-drought nexus in the Southwest, ranging from non-existent or weak (Arcusa et al, 2019;Flagg et al, 2014;Pu & Ginoux, 2017, 2018bRoutson et al, 2019) to moderately strong (Achakulwisut et al, 2017(Achakulwisut et al, , 2019Pu & Ginoux, 2018a;Zender & Kwon, 2005).…”

“…In the U.S. Southwest (hereafter the Southwest), drought is often cited as an important driver of dust emissions (e.g., Aarons et al, 2017Aarons et al, , 2019Achakulwisut et al, 2017Achakulwisut et al, , 2018. Based on this modern relationship, the risk of unprecedented drought projected for the 21st century (Cook et al, 2015) would suggest higher dust emissions in the future (Achakulwisut et al, 2019;Pu & Ginoux, 2017).…”