Impact of Anthropogenic Emissions on Isoprene Photochemical Oxidation Pathways in Central Amazonia
Abstract
The atmosphere over the Amazon rainforest is characterized by high concentrations of biogenic volatile organic compounds (BVOCs) - most notably isoprene, which is the most abundant non-methane VOC both locally and globally. These BVOCs are photochemically oxidized, forming oVOCs, especially via reaction with the hydroxyl radical (OH). This photochemical processing can result in formation of secondary pollutants such as ozone (O3) and secondary organic aerosol (SOA). During the Green Ocean Amazon campaign (GoAmazon2014/5), we obtained formaldehyde and glyoxal measurements together with OH, peroxy radicals (RO2+HO2), nitrogen oxides (NOx), CO, CO2, O3, (o)VOCs, and aerosol particle size distribution. Here we present data collected during 2014 at the T3 field site, 60 km to the west of Manaus, Brazil (3°12'47.82"S, 60°35'55.32"W). The T3 GoAmazon site varies between sampling strictly pristine (biogenic) emissions and influence from anthropogenic emissions from Manaus, depending on meteorological conditions. The day-to-day oscillation provides an ideal setting for evaluating the impact of pollution from biomass burning and urban emissions on VOC oxidation and resultant secondary pollutant production. Anthropogenic plumes contain not only additional VOC precursors, but also enhanced NOx, which drastically alters the relative importance of various isoprene oxidation pathways. We utilize a 0-D photochemical box model to examine how these factors impact reactivity and pollutant formation. Due to ongoing expansion of human influence and emissions in previously-pristine areas, understanding the sensitivity of biogenic oxidation to anthropogenic influence has significant impacts for tropospheric air quality, both in the rapidly-developing Amazon Basin and other BVOC-dominated regions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A43E0273T
- Keywords:
-
- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSESDE: 3355 Regional modeling;
- ATMOSPHERIC PROCESSESDE: 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES