Biogenic volatile organic compound ambient mixing ratios and emission rates in the Alaskan Arctic tundra

Abstract

Abstract. Rapid Arctic warming, a lengthening growing season, and the increasing abundance of biogenic volatile-organic-compound-emitting shrubs are all anticipated to increase atmospheric biogenic volatile organic compounds (BVOCs) in the Arctic atmosphere, with implications for atmospheric oxidation processes and climate feedbacks. Quantifying these changes requires an accurate understanding of the underlying processes driving BVOC emissions in the Arctic. While boreal ecosystems have been widely studied, little attention has been paid to Arctic tundra environments. Here, we report terpenoid (isoprene, monoterpenes, and sesquiterpenes) ambient mixing ratios and emission rates from key dominant vegetation species at Toolik Field Station (TFS; 68∘38′ N, 149∘36′ W) in northern Alaska during two back-to-back field campaigns (summers of 2018 and 2019) covering the entire growing season. Isoprene ambient mixing ratios observed at TFS fell within the range of values reported in the Eurasian taiga (0–500 parts per trillion by volume – pptv), while monoterpene and sesquiterpene ambient mixing ratios were respectively close to and below the instrumental quantification limit (∼2 pptv). Isoprene surface emission rates ranged from 0.2 to 2250 µgC m−2 h−1 (mean of 85 µgC m−2 h−1) and monoterpene emission rates remained, on average, below 1 µgC m−2 h−1 over the course of the study. We further quantified the temperature dependence of isoprene emissions from local vegetation, including Salix spp. (a known isoprene emitter), and compared the results to predictions from the Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1). Our observations suggest a 180 %–215 % emission increase in response to a 3–4 ∘C warming, and the MEGAN2.1 temperature algorithm exhibits a close fit with observations for enclosure temperatures in the 0–30 ∘C range. The data presented here provide a baseline for investigating future changes in the BVOC emission potential of the under-studied Arctic tundra environment.

Synergistic effects of insect herbivory and changing climate on plant volatile emissions in the subarctic tundra

“…Our study showed that experimental warming by ~3°C doubled emissions of total VOCs, monoterpenes, and GLVs. This agrees with several recent studies showing the high sensitivity of plant VOC emissions to temperature rise in the Arctic (Angot et al, 2020;Kramshøj et al, 2016a;Rinnan et al, 2020). While a recent study by Young et al, (2019) found little increase in summer temperatures over recent decades in Northern Fennoscandia, due to increased cloud cover, the high sensitivity of plant VOC emissions to the local temperature increases in the Arctic (Ghirardo et al, 2020;Seco et al, 2020) suggests that even small temperature increases may have strong impacts on plant VOC emissions, with large implications for the atmospheric chemistry processes.…”

Optimizing the Isoprene Emission Model MEGAN With Satellite and Ground‐Based Observational Constraints

“…This demonstrates that the performance of 𝜸 T varies across ecosystems, and that any updates to the parameterization of 𝜸 T should be applied on an ecosystem-specific scale. This has been done previously for Australian eucalypt species (Emmerson et al, 2020), and other studies have demonstrated that this may also be necessary for Arctic vegetation (Angot et al, 2020;Kramshøj et al, 2016;Seco et al, 2020Seco et al, , 2022. Accurately modeling the sensitivity of isoprene emissions to temperature will depend on the development of an ecosystem-specific parameterization for 𝜸 T , which could be derived using our methodology wherever suitable observations are available.…”

“…Model performance is generally good when accurate driving variables are used (Situ et al, 2014; see also Filella et al, 2018;Sarkar et al, 2020), but significant sources of uncertainty remain. These include the empirical parameterization of the standard emission rates and the dimensionless scaling functions, particularly the temperature and drought stress responses (Angot et al, 2020;Guenther et al, 2006;X. Jiang et al, 2018;Kramshøj et al, 2016;Potosnak et al, 2014;Seco et al, 2015Seco et al, , 2020Seco et al, , 2022.…”

“…MEGAN's temperature response algorithm, which simulates the exponential increase in emissions with temperature up to an optimum value (Guenther et al, 1993(Guenther et al, , 1995, is another source of uncertainty. Recent experiments with Arctic vegetation (Angot et al, 2020;Kramshøj et al, 2016;Seco et al, 2020Seco et al, , 2022 and Australian eucalypt trees (Emmerson et al, 2020) have found that MEGAN significantly underestimates isoprene emissions from these species at high temperatures. Updating the parameterization of the temperature response with species-specific measurements in Australia has been shown to improve MEGAN isoprene emissions estimates, with significant consequences for predictions of future ozone pollution in a warming climate (Emmerson et al, 2020).…”

Volatile responses of dwarf birch to mimicked insect herbivory and experimental warming at two elevations in Greenlandic tundra

“…Furthermore, tundra ecosystems are highly heterogeneous and tundra plant responses to warming vary greatly (Bjorkman et al, 2018;Collins et al, 2021). Indeed, previous studies have indicated the unique specificity of tundra VOC emissions as a function of location and vegetation type (Angot et al, 2020;Ghimire et al, 2021;Kramshøj et al, 2016). Thus, field studies in other high-latitude regions are needed to provide a more comprehensive understanding of the sources and drivers of VOC emissions from high-latitude ecosystems.…”