Environmental Engineering Reference
In-Depth Information
8.9 Source Apportionment of Wintertime Secondary
Organic Aerosol During the California Regional
Particulate Matter Study
Jianjun Chen
1
, Qi Ying
2
, and Michael J. Kleeman
1
1
Department of Civil and Environmental Engineering, University of California, Davis,
CA 95616, USA
2
Zachry Department of Civil Engineering, Texas A&M University, College Station,
TX 77843, USA
Abstract
The quantity and origin of secondary organic aerosol (SOA) formation
in the San Joaquin Valley from December 15, 2000 to January 7, 2001 were
studied using the UCD/CIT air quality model with the Caltech Atmospheric
Chemistry Mechanism (CACM). Average SOA concentration across the entire
SJV was 1.4 µg/m
3
, which accounted for approximately 20% of predicted organic
aerosol. Major SOA sources in the SJV were solvent uses (28% of SOA), catalytic
gasoline engines (25% of SOA), wood smoke (16% of SOA), non-catalyst
gasoline engines (13% of SOA), and other anthropogenic sources (11% of SOA).
This study highlighted the importance of considering SOA formation during
wintertime periods in the SJV.
Keywords
CRPAQS, Secondary organic aerosol, UCD/CIT
1. Introduction
The San Joaquin Valley (SJV) in the southern portion of California's Central
Valley is one of the largest PM
2.5
non-attainment areas in the US [1]. Organic
aerosol (OA) is one of the most important constituents of PM
2.5
in the SJV [1]. OA
consists of primary organic aerosol (POA) and secondary organic aerosol (SOA).
While the importance of SOA has been recognized and modeled extensively
during photochemical events, the formation of SOA under wintertime conditions
has only received limited attention. The purpose of this work is to study SOA
formation and source contributions in the SJV between December 15, 2000 and
January 7, 2001. This episode is part of the California Regional Particulate Air
Quality Study (CRPAQS), which was designed to improve our understanding of
the causes of excessive PM levels in central California [1].
