讲座摘要:

Tropospheric oxidation capacity, typically defined as the abundance of tropospheric O3, OH and H2O2, determines the lifetimes of trace gases (e.g., CH4, CO, VOCs) and the production of aerosols in the troposphere. Despite the importance of tropospheric oxidation capacity, its response to anthropogenic and climate forcing is still not well-understood. The chemistry of atmospheric reactive nitrogen, mainly including NOx (NO + NO2) and nitrate (HNO3/NO3-), is highly coupled with tropospheric oxidation capacity. Thus changes in reactive nitrogen chemistry has implications on the variations in tropospheric oxidation capacity, especially given the fact that the oxygen-17 excess (Δ17O, the mass independent fractionation signal of stable oxygen isotopes) of nitrate is indicative of the relative abundance of ambient oxidants when nitrate was formed in the atmosphere.

Polar ice sheets preserve atmospheric nitrate expanding back to hundreds of thousands years. In efforts to provide information on the interactions between oxidation capacity and climate change, we investigate past atmospheric reactive nitrogen chemistry by coupling ice core records of nitrate concentration and its stable isotopic composition (δ15N, Δ17O ) with chemistry-climate modeling. We focus on the preindustrial-present day and glacial-interglacial time scales.

主讲人简介:

 Lei Geng is a post-doctoral research associate in the Department of Atmospheric Sciences at University of Washington. He received his Ph.D. in Chemistry from South Dakota State University in 2012 and his B.S. in Environmental Sciences from University of Science and Technology of China in 2006. Dr. Geng's research primarily focuses on atmospheric chemistry and climatic/environmental records from polar ice sheets. Currently, he utilizes laboratory analyses of ice core chemical impurities and stable isotope tracers coupled with modeling to study the response of atmospheric oxidation chemistry to human influence and climate change on the glacial-interglacial timescale. His work has been featured in UW Today, which is currently in revision for PNAS. Dr. Geng also has reviewed manuscripts for ACP, J. Glaciology and RCMS.