ARB Research Seminar

This page updated July 22, 2016

Source Speciation of Central Valley GHG Emissions Using In-Situ Measurement of Volatile Organic Compounds

Photo of Allen Goldstein

Allen Goldstein

Photo of Mark Fischer

Mark Fischer

Allen Goldstein, Ph.D., Professor, Department of Civil and Environmental Engineering and Department of Environmental Science, Policy and Management, University of California, Berkeley and Marc Fischer, Ph.D., Staff Scientist, Atmospheric Sciences Department, Lawrence Berkeley National Laboratory

August 25, 2016
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA


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Overview

Reducing greenhouse gas (GHG) emissions requires knowledge of the sources and activities which emit GHGs. California's Central Valley has a number of agricultural and natural sources of GHGs in addition to urban, anthropogenic sources. This work investigates the seasonal variability of CH₄ and N₂O source apportionment from year-long measurements of GHGs, CO, and a suite of VOCs in Walnut Grove, about 23 miles south of downtown Sacramento, from summer 2012 through early fall 2013. We apply the statistical technique of positive matrix factorization (PMF) on the combined GHG - VOC data set over seven separate periods that are representative of broad seasonal patterns observed in the region. We also compare our results to inverse modeling estimates at WGC for the same time-period.

Livestock are the largest regional source of CH₄, accounting for a majority of total emissions over different seasons. A second source of CH₄ is observed from microbially-mediated temperature-dependent emissions influenced by land and soil management practices and natural wetland ecosystems. A third 'urban and oil/gas source', containing CH₄ but no N₂O, is theorized to be emitted from an aggregation of upwind sources in the San Francisco Bay Area and the Rio Vista natural gas fields. Only two significant source categories of N₂O are discerned from the PMF analysis - an 'agriculture + soil management + delta' source containing microbe-driven soil emissions of N₂O resulting from fertilizer application and a dairy / livestock manure-management source. Seasonality has a strong influence on CH₄ and N₂O biological emissions and this phenomenon is clearly observed using a top-down measurement approach.

Speaker Biography

Allen H. Goldstein, Ph.D., is currently a Professor in the Department of Civil and Environmental Engineering and in the Department of Environmental Science, Policy, and Management, at the University of California, Berkeley where he served as department chair from 2007-2010. Professor Goldstein is also currently the co-Chair of the International Global Atmospheric Chemistry Program (IGAC). Dr. Goldstein's research program encompasses anthropogenic air pollution, biosphere-atmosphere exchange of radiatively and chemically active trace gases, and development and application of novel instrumentation to investigate the organic chemistry of earth's atmosphere. He engages in field measurement campaigns, controlled laboratory experiments, and modeling activities covering urban, rural, regional, intercontinental, and global scale studies of ozone, aerosols, and their gas phase precursors.

Marc L. Fischer, Ph.D., is a staff scientist with the Atmospheric Sciences Department at the Lawrence Berkeley National Laboratory and an associate scientist in the Department of Geography and Environmental Studies at California State University East Bay. Dr. Fischer's research focuses on measurements and modeling of human-ecosystem-atmosphere processes involving trace gases with an emphasis drivers, responses, and feedbacks to global change. Fischer's work includes field and laboratory trace gas and meteorological measurements, development of spatiotemporally resolved maps of trace gas emissions for the State of California and the continental US, trace gas, and regional inverse modeling of trace gas exchanges between the land surface and atmosphere. Dr. Fischer received his Ph.D. degree in Physics from the University of California, Berkeley in 1991. Dr. Fisher has co-authored over 40 papers in refereed journals. Dr. Fisher is an active member of the American Geophysical Union and other scientific societies, and has (co)-chaired workshops and government-university research meetings.


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