When it’s dusty, it’s dusty: Geochemical insights into the modern and paleo dust cycle
Dr. Sarah Aarons
Assistiant Professor and Isotope Geochemist
Scripps Institute of Oceanography
Host: Dr. Matt Weingarten
Wednesday, November, 13th, 2019
CSL 422 – 1 pm
The generation and transport of mineral dust is strongly related to climate on seasonal, year-to-year, and glacial-interglacial timescales. Mineral dust records climate conditions, and influences climate both directly and indirectly. The production and transport of dust is amplified by global and regional droughts, and can be an important source of critical nutrients capable of enhancing primary productivity in both terrestrial and marine environments. I will discuss dust compositional variations to a montane ecosystem in the context of catastrophic drought conditions, and the role of dust as a source of nutrients to this site. Another aspect of the dust cycle is its behavior on longer timescales; changes in the composition of dust trapped in Antarctic ice provide evidence of past atmospheric circulation and earth surface conditions. I will discuss the sources and transport pathways of dust to the Taylor Glacier, East Antarctica, during several climate periods spanning from the last interglacial period (130,000 years ago) to the present. Distinct dust compositions during separate interglacial periods suggest significant differences in conditions at the dust source areas and a large-scale shift in atmospheric dynamics to this peripheral Antarctic site, perhaps precipitated by deglacial conditions and a reduction of the West Antarctic Ice Sheet. This seminar will detail how I combine chemical compositions and physical characteristics of dust to gain insight into Earth’s atmospheric and terrestrial history, and to better understand the role of dust upon nutrient availability in modern earth systems.
Sarah Aarons is an assistant professor in the Geosciences Research Division at Scripps. Aarons is an isotope geochemist whose research is primarily focused on understanding the evolution of Earth’s surface through time as a function of a changing climate. Her research involves measurement of isotope compositions of natural materials such as mineral dust, weathering profiles, river sediment, and ancient rocks. The majority of her research is concentrated on mineral dust, fine grained sediment that is blown up into the atmosphere and transported thousands of miles before it’s deposited in glaciers, ice sheets, and terrestrial ecosystems. Her projects include tracing dust transport during large scale climate transitions, probing the ecological significance of modern dust, and quantifying changes in nutrient fluxes due to glacial retreat. Her work involves field campaigns in Antarctica, Alaska, and California, clean lab chemistry, and mass spectrometry. She completed a postdoctoral fellowship at the University of Chicago and is now at Scripps. Aarons holds an MS and PhD in Earth and environmental science from the University of Michigan and a BS in geological and environmental science from Stanford University.