Sesquiterpenes dominate monoterpenes in northern wetland emissions

Hellén, Heidi; Schallhart, Simon; Praplan, Arnaud P.; Tykkä, Toni; Aurela, Mika; Lohila, Annalea; Hakola, Hannele

doi:10.5194/acp-20-7021-2020

Cited by 31 publications

(29 citation statements)

References 35 publications

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“…5) than to surface temperature. At the same Stordalen wetland as our study, Holst et al (2010) found a steep temperature response to air temperatures above 15 • C, in agreement with our results ( Fig. 5) and previous high-latitude studies (Kramshøj et al, 2016;Lindwall et al, 2016a, b;Rinnan et al, 2014).…”

supporting

confidence: 94%

“…Regarding methanol, EC fluxes investigated at the Stordalen mire wetland by Holst et al (2010) reached a noontime average hourly maximum of 1.3 nmol m −2 s −1 in early August, which is higher than our 0.2 nmol m −2 s −1 in July (Fig. 3).…”

contrasting

confidence: 74%

“…Several biogenic VOC studies in recent years have revealed that isoprene is the major compound in VOC emissions of many arctic and subarctic ecosystems (Holst et al, 2010;Potosnak et al, 2013;Tiiva et al, 2007), including leaf-level measurements of two of the dominant sedge species of our fen: C. rostrata and E. angustifolium (Ekberg et al, 2009). Only two studies, though, measured the ecosystem-scale emissions with EC, one nearby in the Stordalen mire fen and the other in an Alaskan moist acidic tundra (Holst et al, 2010;Potosnak et al, 2013). They published maximum hourly isoprene fluxes that were in the range of 1 to 5.5 nmol m −2 s −1 at the peak of the growing season, comparable in magnitude to our July fen measurements ( Fig.…”

Section: Fen Voc Fluxesmentioning

confidence: 99%

“…Micrometeorological techniques such as eddy covariance (EC) can overcome many of those undesirable side effects and, in addition, provide a more representative ecosystem-level VOC exchange quantification by minimizing potential sampling error when upscaling from a small number of enclosures to ecosystem fluxes. However, instrumental challenges have limited the number of ecosystemlevel VOC studies using EC, and only two such datasets over short time periods are available for high-latitude ecosystems (Holst et al, 2010;Potosnak et al, 2013). Moreover, there are few or no air-water direct VOC flux measurements from northern lakes.…”

Section: Introductionmentioning

confidence: 99%

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Volatile organic compound fluxes in a subarctic peatland and lake

et al. 2020

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Abstract. Ecosystems exchange climate-relevant trace gases with the atmosphere, including volatile organic compounds (VOCs) that are a small but highly reactive part of the carbon cycle. VOCs have important ecological functions and implications for atmospheric chemistry and climate. We measured the ecosystem-level surface–atmosphere VOC fluxes using the eddy covariance technique at a shallow subarctic lake and an adjacent graminoid-dominated fen in northern Sweden during two contrasting periods: the peak growing season (mid-July) and the senescent period post-growing season (September–October). In July, the fen was a net source of methanol, acetaldehyde, acetone, dimethyl sulfide, isoprene, and monoterpenes. All of these VOCs showed a diel cycle of emission with maxima around noon and isoprene dominated the fluxes (93±22 µmol m−2 d−1, mean ± SE). Isoprene emission was strongly stimulated by temperature and presented a steeper response to temperature (Q10=14.5) than that typically assumed in biogenic emission models, supporting the high temperature sensitivity of arctic vegetation. In September, net emissions of methanol and isoprene were drastically reduced, while acetaldehyde and acetone were deposited to the fen, with rates of up to -6.7±2.8 µmol m−2 d−1 for acetaldehyde. Remarkably, the lake was a sink for acetaldehyde and acetone during both periods, with average fluxes up to -19±1.3 µmol m−2 d−1 of acetone in July and up to -8.5±2.3 µmol m−2 d−1 of acetaldehyde in September. The deposition of both carbonyl compounds correlated with their atmospheric mixing ratios, with deposition velocities of -0.23±0.01 and -0.68±0.03 cm s−1 for acetone and acetaldehyde, respectively. Even though these VOC fluxes represented less than 0.5 % and less than 5 % of the CO2 and CH4 net carbon ecosystem exchange, respectively, VOCs alter the oxidation capacity of the atmosphere. Thus, understanding the response of their emissions to climate change is important for accurate prediction of the future climatic conditions in this rapidly warming area of the planet.

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supporting

confidence: 94%

contrasting

confidence: 74%

Section: Fen Voc Fluxesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Volatile organic compound fluxes in a subarctic peatland and lake

et al. 2020

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“…Other experiments in nearby Abisko heaths, mentioned above, documented sesquiterpene flux rates similar to those of monoterpenes measured in the same study (Faubert et al, 2010a;Valolahti et al, 2015). Most recently, sesquiterpenes have been detected as the main terpenoid emissions after isoprene at a subarctic wetland in Finland (Hellén et al, 2020). One obvious reason for our lack of sesquiterpene signal is that our flux footprint did not include a significant amount of high-emitting species since, for example, most of the nearby birch patches were outside of it.…”

Section: Fen Voc Fluxessupporting

confidence: 72%

Volatile Organic Compound fluxes in a subarctic peatland and lake

Seco,

Holst,

Matzen

et al. 2020

Preprint

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Abstract. Ecosystems exchange climate-relevant trace gases with the atmosphere, including volatile organic compounds (VOCs) that are a small but highly reactive part of the carbon cycle. VOCs have important ecological functions and implications for atmospheric chemistry and climate. We measured the ecosystem-level surface-atmosphere VOC fluxes using the eddy covariance technique at a shallow subarctic lake and an adjacent graminoid-dominated fen in Northern Sweden during two contrasting periods: the peak growing season (mid July) and the senescent period post-growing season (September–October). In July, the fen was a net source of methanol, acetaldehyde, acetone, DMS, isoprene, and monoterpenes. All of these VOCs showed a diel cycle of emission with maxima around noon and isoprene dominated the fluxes (93 ± 22 µmol m−2 day−1, mean ± SE). Isoprene emission was strongly stimulated by temperature and presented a steeper response to temperature (Q10 = 14.5) than that typically assumed in biogenic emission models, supporting the high temperature sensitivity of arctic vegetation. In September, net emissions of methanol and isoprene were drastically reduced, while acetaldehyde and acetone were deposited to the fen, with rates of up to −6.7 ± 2.8 µmol m−2 day−1 for acetaldehyde. Remarkably, the lake was a sink for acetaldehyde and acetone during both periods, with average fluxes up to −19 ± 1.3 µmol m−2 day−1 of acetone in July and up to −8.5 ± 2.3 µmol m−2 day−1 of acetaldehyde in September. The deposition of both carbonyl compounds correlated with their atmospheric mixing ratios, with deposition velocities of −0.23 ± 0.01 and −0.68 ± 0.03 cm s−1 for acetone and acetaldehyde, respectively. Even though these VOC fluxes represented less than 0.5 % and less than 5 % of the CO2 and CH4 net carbon ecosystem exchange, respectively, VOCs alter the oxidation capacity of the atmosphere. Thus, understanding the response of their emissions to climate change is important for accurate prediction of the future climatic conditions in this rapidly warming area of the planet.

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