Volatile Organic Compounds in the Global Atmosphere

Abstract

Volatile organic compounds (VOCs) include saturated, unsaturated, and other substituted hydrocarbons. VOCs play an important role in the chemistry of the atmosphere by influencing ozone and hydroxyl radical (OH) concentrations, and the conversion rates of nitrogen oxides (NOx). Elevated levels of VOCs and NOx have led to an approximate doubling of ozone in the lower troposphere over the past couple of centuries, making tropospheric ozone the third most important anthropogenic greenhouse gas after carbon dioxide (CO2) and methane. Because of ozone's strong oxidizing properties, increases in tropospheric ozone are a concern for living systems on Earth. Ozone stresses and damages vegetation, resulting in a reduction of terrestrial CO2 sequestration. VOCs also serve as a source of atmospheric secondary organic aerosol (SOA), which influences the solar radiation budget and cloud droplet nucleation. Through these complex interactions, VOCs play an important role in air quality and climate.

The influence of biomass burning on the global distribution of selected non-methane organic compounds

“…Plass-Duelmer et al, 2002;Read et al, 2009;Simpson et al, 2012). Recognizing the importance of addressing the limited extent of measurements relative to other atmospheric species, the World Meteorological Organization now has a specific long-term monitoring activity for volatile organic compounds (VOCs) as part of the Global Atmosphere Watch programme (WMO-GAW) (Helmig et al, 2009). NMHCs including ethane, propane, acetylene, butane and pentane form part of the target suite of compounds (WMO technical document 2007) in this network.…”

Changes to the chemical state of the Northern Hemisphere atmosphere during the second half of the twentieth century

“…Swanson et al, 2003;Helmig et al, 2009) due to changes in their chemical lifetimes (∼ 1 month in the winter and 4-5 days in the summer) driven by the seasonal cycle in OH concentration.…”

A five year record of high-frequency in situ measurements of non-methane hydrocarbons at Mace Head, Ireland

“…We would like to note that this five year record is a rather short dataset from which to estimate long-term atmospheric trends however we have included these to enable initial comparison to other available datasets. Other studies have calculated long-term trends using ten year datasets and propose this to be the minimum length dataset over which one can verify a "long-term" trend (for example von Schneidemesser et al, 2010;Dollard et al, 2007;Hakola et al, 2006;Helmig et al, 2009).…”