Changes in monoterpene mixing ratios during summer storms in rural New Hampshire (USA)

Abstract

Abstract.Monoterpenes are an important class of biogenic hydrocarbons that influence ambient air quality and are a principle source of secondary organic aerosol (SOA). Emitted from vegetation, monoterpenes are a product of photosynthesis and act as a response to a variety of environmental factors. Most parameterizations of monoterpene emissions are based on clear weather models that do not take into account episodic conditions that can drastically change production and release rates into the atmosphere. Here, the monoterpene dataset from the rural Thompson Farm measurement site in Durham, New Hampshire is examined in the context of a set of known severe storm events. While some storm systems had a negligible influence on ambient monoterpene mixing ratios, the average storm event increased mixing ratios by 0.59 ± 0.21 ppbv, a factor of 93 % above pre-storm levels. In some events, mixing ratios reached the 10's of ppbv range and persisted overnight. These mixing ratios correspond to increases in the monoterpene emission rate, ranging from 120 to 1240 g km −2 h −1 compared to an estimated clear weather rate of 116 to 193 g km −2 h −1 . Considering the regularity of storm events over most forested areas, this could be an important factor to consider when modeling global monoterpene emissions and their resulting influence on the formation of organic aerosols.

Undisturbed and disturbed above canopy ponderosa pine emissions: PTR-TOF-MS measurements and MEGAN 2.1 model results

“…3.4, Table 7). Elevated monoterpene concentrations and fluxes after mechanical wounding have been previously observed (Bouvier-Brown et al, 2009;Haase et al, 2011;Bamberger et al, 2011;Holzinger et al, 2006). New in this study is that a natural event such as a hailstorm can cause such a strong mechanical damage to enhance monoterpene emissions by a factor of 4-23 as well as the enhancement of several other compounds such as cymene, camphor, nopinone, pinonaldehyde and the sum of sesquiterpenes.…”

“…Most emission measurements have focused on VOC emissions of intact and undamaged plants; however, studies by Schade and Goldstein (2003), Räisänen et al (2008) and demonstrated enhanced monoterpene fluxes after mechanical wounding on the ecosystem scale. A few studies also reported enhanced mixing ratios of monoterpenes and sesquiterpenes after severe storms (Helmig et al, 1998;Bouvier-Braun et al, 2009;Haase et al, 2011;. Holzinger et al (2006) reported increased monoterpene emissions on days following rain events.…”

Biotic stress: a significant contributor to organic aerosol in Europe?

“…Monoterpene emissions (from storage pools) are often increased due to plant stress (especially as a consequence of mechanical wounding; Juuti et al, 1990, Schade and Goldstein, 2003, Haase et al, 2011, Kaser et al, 2013. However, in this study all MT emissions were assigned to the constitutive emissions, based on the fact that the MT emissions measured during the JPAC experiments were quite similar to those measured for unstressed plants of the same species.…”

Temperature-dependent rate coefficients for the reactions of the hydroxyl radical with the atmospheric biogenics isoprene, alpha-pinene and delta-3-carene

“…Throughout the year shorter bursts of terpene emission, associated with damage induced by e.g. animals (Heijari et al, 2011), pathogens, storms (Haase et al, 2011) and harvesting, may impact on the local OH budget (Noelscher et al, 2012). Elsewhere, monoterpenes have been detected from other vegetation, notably the forest floor (Hellen et al, 2006) and over active phytoplankton blooms in the Southern Ocean (Yassaa et al, 2008).…”