Work

Evidence of 1991–2013 decrease of biogenic secondary organic aerosol in response to SO 2 emission controls

Year: 2017

Type: article

Abstract: Air quality policy to decrease fine particulate matter mass concentrations (PM 2.5 ) in the US has mainly targeted sulfate aerosol through controls on sulfur dioxide (SO 2 ) emissions. Organic aerosol (OA) instead of sulfate is now the dominant component of total PM 2.5 . Long-term surface observations (1991–2013) in the Southeast US in summer show parallel decreases in sulfate (2.8%–4.0% a −1 ) and OA (1.6%–1.9% a −1 ). Decline of anthropogenic OA emissions is uncertain but is unlikely to fully explain this trend because most OA in the Southeast US in summer is biogenic. We conducted a 1991–2013 simulation with the GEOS-Chem chemical transport model including inventory decreases in anthropogenic SO 2 , NO x , and volatile organic compounds (VOCs) emissions, constant anthropogenic primary OA emissions, and a new mechanism of aqueous-phase SOA formation from isoprene. This simulation reproduces the observed long-term decreases of sulfate and OA, and attributes the OA decrease to decline in the OA yield from biogenic isoprene as sulfate decreases (driving lower aqueous aerosol volume and acidity). Interannual OA variability in the model (mainly driven by isoprene) is also well correlated with observations. This result provides support for a large air quality co-benefit of SO 2 emission controls in decreasing biogenic OA as well as sulfate.

Source: Environmental Research Letters

DOI: 10.1088/1748-9326/aa69c8

Authors: Eloise A Marais, Daniel J Jacob, Jay R Turner, Loretta J Mickley

Institutions: Harvard University, University of Birmingham, Washington University in St. Louis

Language: English

Topic: Atmospheric chemistry and aerosols

Subfield: Atmospheric Science

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDG: Climate action

Open Access status: gold

Estimated APC paid: $3,045