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Within-canopy sesquiterpene ozonolysis in Amazonia

Yáñez Serrano, Ana Maria (2011) In Lunds universitets Naturgeografiska institution - Seminarieuppsatser
Dept of Physical Geography and Ecosystem Science
Abstract (Swedish)
Populärvetenskaplig sammanfattning: En mycket reaktiv spårgas i Amazonas. Växter släpper ut flyktiga organiska ämnen, som är mycket viktiga eftersom de släpps
ut i stora mängder och påverkar tillverkningen av aerosoler, förändrar luftkvaliteten och
fungerar som kommunikation mellan växter och herbivorer. Det här arbetet presenterar
uppmätningar av sesquiterpener, vilka är flyktiga organiska partiklarna inom gruppen
isoprenoider, de har de största utsläpps grupperna. Sesquiterpener är mycket reaktiva
och finns därför i väldigt små koncentrationer, därför har det inte varit möjligt att mäta
dem tidigare. Här presenteras de första mätningarna av sesquiterpener i ett flux torn i en
central amazon region, detta låter oss se... (More)
Populärvetenskaplig sammanfattning: En mycket reaktiv spårgas i Amazonas. Växter släpper ut flyktiga organiska ämnen, som är mycket viktiga eftersom de släpps
ut i stora mängder och påverkar tillverkningen av aerosoler, förändrar luftkvaliteten och
fungerar som kommunikation mellan växter och herbivorer. Det här arbetet presenterar
uppmätningar av sesquiterpener, vilka är flyktiga organiska partiklarna inom gruppen
isoprenoider, de har de största utsläpps grupperna. Sesquiterpener är mycket reaktiva
och finns därför i väldigt små koncentrationer, därför har det inte varit möjligt att mäta
dem tidigare. Här presenteras de första mätningarna av sesquiterpener i ett flux torn i en
central amazon region, detta låter oss se sesquiterpenernas roll i trädkronorna. För att få
mätningarna användes en ’Proton Transfer Reaction Mass Spectrometer’ som har
insläpp på olika höjder från 2 till 40 meter. Vårt resultat tyder på att sesquiterpenerna är
invert relaterade till ozon, eftersom sesquiterpenerna visar höga koncentrationer under
natten, och ozon visar höga koncentrationer under dagen. Därför, i Amazonas, är
sesquiterpenernas koncentration bestämda av ozon, vilket är deras sink, eftersom
sesquiterpener försvinner från systemet som en följd av deras reaktion med ozonet.
Detta medför att en serie av möjlig feedback mekanismer för klimatet förklaras, men det
behövs många fler undersökningar för att man ska kunna bekräfta alla dessa processer. (Less)
Abstract
Sesquiterpenes are highly reactive terpenoids produced by vegetation and may serve
many important biological functions such as acting as antioxidants and as
semiochemicals (chemicals acting as messengers within or between species). Once
emitted to the atmosphere, by reacting with oxidants like ozone and contributing to
secondary organic aerosol formation, the emission of sesquiterpenes from vegetation
may have significant impacts on radiation balance and precipitation dynamics. Although
it is known that sesquiterpenes have short atmospheric lifetimes of a few minutes,
analytical difficulties stemming from low concentrations, high reactivities, and high
“stickiness” have so far prevented the detailed characterization of... (More)
Sesquiterpenes are highly reactive terpenoids produced by vegetation and may serve
many important biological functions such as acting as antioxidants and as
semiochemicals (chemicals acting as messengers within or between species). Once
emitted to the atmosphere, by reacting with oxidants like ozone and contributing to
secondary organic aerosol formation, the emission of sesquiterpenes from vegetation
may have significant impacts on radiation balance and precipitation dynamics. Although
it is known that sesquiterpenes have short atmospheric lifetimes of a few minutes,
analytical difficulties stemming from low concentrations, high reactivities, and high
“stickiness” have so far prevented the detailed characterization of within-canopy
sources and sinks. Therefore little is known about sesquiterpene emissions and
chemistry within canopies. This study presents the first ambient air profile observations
of rapid sesquiterpene ozonolysis reactions obtained during the BrazilianAir 2010 field
campaign in Central Amazonia, from September 2010 to February 2011. Our results
show that sesquiterpene concentrations followed a very different pattern compared to
isoprene and monoterpenes, by peaking at night instead of during the day and peaking
near the ground instead of within the canopy. Furthermore, their concentrations were
inversely related with ozone, suggesting that sesquiterpene concentrations were more
strongly determined by ozonolysis rather than by emissions, which is further
corroborated by experiments done in Biosphere 2, Arizona, where no oxidation was
taking place and sesquiterpenes followed the same diurnal pattern as isoprene and
monoterpenes. These observations suggest rapid ozonolysis reactions within the canopy
which strongly determine sesquiterpene concentrations in both time and space.
Moreover, calculated sesquiterpene ozonolysis rates peaked during midday at a height
of ca. 20m above ground, suggesting that they are mainly determined by the high ozone
concentrations during the day. We conclude that ambient concentrations of
sesquiterpenes are not necessarily low because of low plant emissions, but rather high
ozonolysis rates which were unaccounted for in previous ambient air studies. Our
findings should help to better understand the environmental and biological controls on
the dynamics of chemical emission, loss, and transport of highly reactive species like
sesquiterpenes within canopies and their potential biological and atmospheric impacts.
In particular, our observations suggest that the fraction of emitted sesquiterpenes lost
within the canopy to ozonolysis could be large and that this process reduces ozone
concentrations thereby providing plants protection against exogenous reactive oxygen
species. (Less)
Please use this url to cite or link to this publication:
author
Yáñez Serrano, Ana Maria
supervisor
organization
alternative title
En mycket reaktiv spårgas i Amazonas
year
type
H2 - Master's Degree (Two Years)
subject
keywords
sesquiterpenes, ozonolysis, ozone, Amazon, oxidation
publication/series
Lunds universitets Naturgeografiska institution - Seminarieuppsatser
report number
217
funder
National Science Foundation (NSF)
funder
Philecology Foundation of Fort Worth, Texas
language
English
additional info
Master degree thesis, 30 credits in Atmospheric Sciences & Biogeochemical Cycles. Department of Physical Geography and Ecosystems Science, Lund University.

Funding for this project was provided by the Philecology Foundation of Fort Worth, Texas and the National Science Foundation through the AMAZON-PIRE (Partnerships for International Research and Education) award (0730305) and instrumentation support (CHE 0216226).


id
2155836
date added to LUP
2011-12-28 14:51:53
date last changed
2014-06-19 08:46:13
@misc{2155836,
  abstract     = {Sesquiterpenes are highly reactive terpenoids produced by vegetation and may serve
many important biological functions such as acting as antioxidants and as
semiochemicals (chemicals acting as messengers within or between species). Once
emitted to the atmosphere, by reacting with oxidants like ozone and contributing to
secondary organic aerosol formation, the emission of sesquiterpenes from vegetation
may have significant impacts on radiation balance and precipitation dynamics. Although
it is known that sesquiterpenes have short atmospheric lifetimes of a few minutes,
analytical difficulties stemming from low concentrations, high reactivities, and high
“stickiness” have so far prevented the detailed characterization of within-canopy
sources and sinks. Therefore little is known about sesquiterpene emissions and
chemistry within canopies. This study presents the first ambient air profile observations
of rapid sesquiterpene ozonolysis reactions obtained during the BrazilianAir 2010 field
campaign in Central Amazonia, from September 2010 to February 2011. Our results
show that sesquiterpene concentrations followed a very different pattern compared to
isoprene and monoterpenes, by peaking at night instead of during the day and peaking
near the ground instead of within the canopy. Furthermore, their concentrations were
inversely related with ozone, suggesting that sesquiterpene concentrations were more
strongly determined by ozonolysis rather than by emissions, which is further
corroborated by experiments done in Biosphere 2, Arizona, where no oxidation was
taking place and sesquiterpenes followed the same diurnal pattern as isoprene and
monoterpenes. These observations suggest rapid ozonolysis reactions within the canopy
which strongly determine sesquiterpene concentrations in both time and space.
Moreover, calculated sesquiterpene ozonolysis rates peaked during midday at a height
of ca. 20m above ground, suggesting that they are mainly determined by the high ozone
concentrations during the day. We conclude that ambient concentrations of
sesquiterpenes are not necessarily low because of low plant emissions, but rather high
ozonolysis rates which were unaccounted for in previous ambient air studies. Our
findings should help to better understand the environmental and biological controls on
the dynamics of chemical emission, loss, and transport of highly reactive species like
sesquiterpenes within canopies and their potential biological and atmospheric impacts.
In particular, our observations suggest that the fraction of emitted sesquiterpenes lost
within the canopy to ozonolysis could be large and that this process reduces ozone
concentrations thereby providing plants protection against exogenous reactive oxygen
species.},
  author       = {Yáñez Serrano, Ana Maria},
  keyword      = {sesquiterpenes,ozonolysis,ozone,Amazon,oxidation},
  language     = {eng},
  note         = {Student Paper},
  series       = {Lunds universitets Naturgeografiska institution - Seminarieuppsatser},
  title        = {Within-canopy sesquiterpene ozonolysis in Amazonia},
  year         = {2011},
}