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Upcoming Seminar

Sources and Characteristics of Particulate Matter in an Urban/Agricultural/Desert Setting

Wed, Jan 27, 2021

270 Seminar

Speaker: Roya Bahreini

Institution: UC Riverside

Abstract:

The Imperial Valley is the second largest agricultural region in California and is home to the Salton Sea, the largest endorheic lake west of the Mississippi. The Imperial County communities surrounding the Salton Sea suffer from extreme levels of air pollution, especially aerosol particles. This has led to negative health outcomes and low socioeconomic factors. Due to the high input of agricultural runoffs in the lake over the past decades, its salinity has been increasing to twice as much as ocean water. Additionally, concentrations of selenium (Se) in the water and sediments are high and increasing. Recent water management practices in the region have led to a sharp decrease in the Salton Sea water levels, worsening its water quality, and exposing the playa along its shores. Primary dust emissions from the recently exposed playa mobilize trace pollutants to the atmosphere and contribute to the region’s PM2.5 and PM10 (aerosols ≤ 2.5 mm and 10 mm in aerodynamic size, respectively) concentrations.

In this talk, I present results on mineral and ionic composition of suspended and depositing aerosols in Imperial Valley to determine sources of airborne dust particles and quantify the influence of the exposed playa vs. the local arid lands in controlling dust emissions. I will also examine the spatial and temporal patterns of aerosol components using data from passive samplers deployed at five sites, spanning from the remote/background to urban and shoreline locations in IV. Enrichment factors and positive matrix factorization (PMF) results were used to identify and to estimate the contribution of various dust sources in the region. The PMF resolved the data from these samplers with seven factors, six of which have anthropogenic influences, contributing to 55-80% of the collected aerosol mass. Additionally, we determined that playa emissions were most intense during late spring/early summer. Minerology of the collected samples during an intense dust event suggest that evaporite minerals of playa, particularly magnesium and sulfate, are important for playa emissivity. In our first study at the Salton Sea, we observed strong seasonal variations in Se concentrations with higher enrichments on fine aerosols, suggesting a seasonal cycle of Se volatilization from the playa and/or the sediments and formation of secondary aerosols through condensation. I will conclude the seminar with results from our laboratory-based experiments examining the potential for atmospheric oxidation of organoselenium compounds to contribute to Se-enrichment in ambient aerosols.

Zoom: https://ucla.zoom.us/j/98770296517

Adeyemi Adebiyi	Postdoctoral Scholar	aadebiyi [at] ucla.edu
Fiaz Ahmed	Assistant Project Scientist
Xin An	Postdoctoral Scholar	xinan [at] atmos.ucla.edu
Homayon Aryan	Associate researcher	homayonaryan [at] atmos.ucla.edu
Roy Bakan	Assistant Researcher
Benjamin Bass		benb0228 [at] g.ucla.edu
Maria Esther Capo Truyols		estheraula [at] gmail.com
Mickael D. Chekroun	Associate researcher	mchekroun [at] atmos.ucla.edu
Di Chen	dichen@atmos.ucla.edu
Seth Claudepierre	Associate researcher	sethclaudepierre [at] atmos.ucla.edu
Santo Fedele Colosimo	Assistant Researcher	fedele [at] atmos.ucla.edu
Sol Cooperdock	Project Scientist	cooperdock [at] atmos.ucla.edu
Daniel Dauhajre	Postdoctoral Scholar	ddauhajre [at] atmos.ucla.edu
Charles Dong	Research Professor	cdong [at] atmos.ucla.edu
Jerome Guiet		jguiet [at] atmos.ucla.edu
Michael Heisel		heisel [at] ucla.edu
Delphine Hypolite	Postdoctoral Scholar
Arjun Jagannathan	Postdoctoral Scholar
Heejeong Kim	Assistant Researcher	heekim [at] atmos.ucla.edu	MS 7115
Dmitri Kondrashov	Researcher	dkondras [at] atmos.ucla.edu	MS 7232
Wen Li	Associate researcher	moonli [at] atmos.ucla.edu	MS 7984
Jinxing Li	Assistant Researcher	jli [at] atmos.ucla.edu
Qianli Ma	Assistant Researcher	qianlima [at] atmos.ucla.edu
Jeroen Molemaker	Associate researcher	nmolem [at] atmos.ucla.edu
Allison Moreno		allimoreno [at] atmos.ucla.edu
Yukitoshi Nishimura	Associate researcher	toshi [at] atmos.ucla.edu	MS 7115
Jesse Norris	Project Scientist	jessenorris [at] ucla.edu	MS 7235
Olga Pikelnaya	Assistant Researcher	olga [at] atmos.ucla.edu
Lionel Renault	Assistant Researcher
Kaushik Srinivasan	Assistant Researcher	kaushiks [at] ucla.edu
Chad Thackeray	Postdoctoral Scholar
Chih-Ping Wang	Researcher	cat [at] atmos.ucla.edu	MS 7115
Peng Wang	Postdoctoral Scholar
Chao Yan	Postdoctoral Scholar	yanchao11 [at] tsinghua.org.cn
Luwei Yang		luweiy [at] atmos.ucla.edu
Simon Yang	Assistant Project Scientist	yangsi [at] ucla.edu
Xinxin Ye	Postdoctoral Scholar
Chao Yue	Assistant Researcher	yuechao [at] atmos.ucla.edu
Pengfei Zhang	Postdoctoral Scholar	zpengfei [at] atmos.ucla.edu
Siyu Zhao		siyu_zhao [at] atmos.ucla.edu
Yizhou Zhuang		zhuangyz [at] atmos.ucla.edu

46°

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