Seasonal trends of biogenic terpene emissions

Abstract

h i g h l i g h t sFull year study on biogenic volatile organic compounds emissions. Description of seasonal changes of basal emission rates. Investigation of seasonal behavior of temperature response. Sensitivity analysis for modeling of biogenic volatile organic compound emissions. a b s t r a c t Biogenic volatile organic compound (BVOC) emissions from six coniferous tree species, i.e. Pinus ponderosa (Ponderosa Pine), Picea pungens (Blue Spruce), Pseudotsuga menziesii (Rocky Mountain Douglas Fir) and Pinus longaeva (Bristlecone Pine), as well as from two deciduous species, Quercus gambelii (Gamble Oak) and Betula occidentalis (Western River Birch) were studied over a full annual growing cycle. Monoterpene (MT) and sesquiterpene (SQT) emissions rates were quantified in a total of 1236 individual branch enclosure samples. MT dominated coniferous emissions, producing greater than 95% of BVOC emissions. MT and SQT demonstrated short-term emission dependence with temperature. Two oxygenated MT, 1,8-cineol and piperitone, were both light and temperature dependent. Basal emission rates (BER, normalized to 1000 lmol m À2 s À1 and 30°C) were generally higher in spring and summer than in winter; MT seasonal BER from the coniferous trees maximized between 1.5 and 6.0 lg g À1 h À1 , while seasonal lows were near 0.1 lg g À1 h À1 . The fractional contribution of individual MT to total emissions was found to fluctuate with season. SQT BER measured from the coniferous trees ranged from <0.01 to 0.15 lg g À1 h À1 . BER of up to 1.2 lg g À1 h À1 of the SQT germacrene B were found from Q. gambelii, peaking in late summer. The b-factor, used to define temperature dependence in emissions modeling, was not found to exhibit discernible growth season trends. A seasonal correction factor proposed by others in previous work to account for a sinusoidal shaped emission pattern was applied to the data. Varying levels of agreement were found between the data and model results for the different plant species seasonal data sets using this correction. Consequently, the analyses on this extensive data set suggest that it is not feasible to apply a universal seasonal correction factor across different vegetation species. A modeling exercise comparing two case scenarios, (1) without and (2) with consideration of the seasonal changes in emission factors illustrated large deviations when emission factors are applied for other seasons than those in which they were experimentally determined. a r t i c l e i n f o

Impacts of simulated herbivory on volatile organic compound emission profiles from coniferous plants

“…The activity adjustment factors calculated here ranged from 0.15 to 0.59 K −1 , with most values ranging from 0.15 to 0.26 K −1 . Where a relationship between temperature and emission rate was observed and an activity adjustment factor could be calculated, nearly all values calculated for the terpenes were consistent with the ranges previously reported for coniferous tree species by Helmig et al (2013) and Ortega et al (2008) (0.08 to 0.28 K −1 ) (0.00 to 0.23 K −1 ). The one exception was the activity adjustment factor calculated for Pseudotsuga menziesii, which was much higher than any of the others, but which also had the highest temperature/emission rate (ER) correlation observed from any experiment (r 2 = 0.91 for monoterpenes and r 2 = 0.89 for aromatics).…”

“…Each of these profiles were consistent with previous measurements made in a field setting. The Picea pungens monoterpene profile presented by Helmig et al (2013) had higher contributions from alpha-pinene in spring, but decreased in August and September in a manner similar to what we observed in July. Furthermore, we observed an increase in the contribution of Figure 1.…”

“…The Picea pungens monoterpenoid BER in this study ranged from 0.29 to 0.81 µg-C g −1 h −1 (0.32-0.92 µg g −1 h −1 ). Previous reports ranged from < 0.10 to 1.45 µg g −1 h −1 throughout the year, and during the months of May-July (the time period when our experiments were performed) the reported BER range was 0.87-1.45 µg g −1 h −1 (Helmig et al, 2013). Thus, the Picea pungens BER in our experiments was on the lower end of what has been reported from Picea pungens in the field.…”

“…1,8-cineol in the July experiments vs. the May experiment, which Helmig et al (2013) also described. The Picea pungens monoterpenoid BER in this study ranged from 0.29 to 0.81 µg-C g −1 h −1 (0.32-0.92 µg g −1 h −1 ).…”

Carbon monoxide isotopic measurements in Indianapolis constrain urban source isotopic signatures and support mobile fossil fuel emissions as the dominant wintertime CO source

“…Compounds such as OH and O 3 readily oxidize CH 4 and many NMHCs (Sander et al, 2006;Warneke et al, 2013;Russo et al, 2011;Khan et al, 2015) making them seasonally-varying sources of CO (Duncan et al, 2007). However, the relatively low wintertime NMHC and OH mole fractions (Helmig et al, 2013;Hu et al, 2015) mean that CH 4 and NMHC oxidation may be unimportant for our study. Not all NMHC species capable of impacting CO are measured at INX; therefore some of the NMHC mole fractions are estimated using other urban studies in the literature (Warneke et al, 2013;Russo et al, 2011;Khan et al, 2015) (Table S2, supplemental material).…”