Leaf level emissions of volatile organic compounds (VOC from some Amazonian and ...

19 Pages·2013·0.67 MB·English

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Biogeosciences,10,5855–5873,2013 O O
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www.biogeosciences.net/10/5855/2013/ e Biogeosciencese
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doi:10.5194/bg-10-5855-2013 Biogeosciences A A
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Leaf level emissions of volatile organic compounds (VOC) from
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some Amazonian and Mediterranean plants p Earth System p
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A Dynamics A
Dynamicsc c
A.Bracho-Nunez1,2,N.M.Knothe,1,S.Welter1,2,M.Staudt2,W.R.Costa3,M.A.R.Liberato4,M.T.F.Pceiedade3,and ce
s Discussionss
J.Kesselmeier1 s s
1MaxPlanckInstituteforChemistry,Hahn-Meitner-Weg1,55128Mainz,Germany
Geoscientific Geoscientific
2Centred’EcologieFonctionnelleetEvolutive,UMR5175,54293Montpellier,France O O
p p
3InstitutoNacionaldePesquisasdaAmazoˆnia,Av.Andre´ Arau´jo,2936Manaus,Brazil Instrumentation en Instrumentation en
4UniversidadedoEstadodoAmazonas,Av.DjalmaBatista,Chapada,69050-010Manaus,AMM,eBtrhaozidl s and Ac Methods and Ac
c c
e e
Correspondenceto:([email protected]) Data Systemsss Data Systemsss
Discussions
Received:17August2012–PublishedinBiogeosciencesDiscuss.:1November2012 O GeoscientificO
Revised:21July2013–Accepted:26July2013–Published:6September2013 Geoscientificpe pe
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A Model Development A
Model Developmentcc cc
e e
Abstract.Emissioninventoriesdefiningregionalandglobal thermore, our screening activities cover onlyss1% of tree Discussionsss
biogenic volatile organic compounds (VOC) emission species of such tropical areas as estimated based on re-
strengthsareneededtodeterminetheimpactofVOConat- cent biodiversity reportHs.yMderthoanloolgeym iassniodns ,Oan indicator Hydrology and O
mospheric chemistry (oxidative capacity) and physics (sec- of growth, were found to be common in mospet of the trop- pe
ondary organic aerosol formation and effects). The aim ical and Mediterranean Espeacrietsh. ASyfeswtespmecin Aes from both Earth Systemn A
c c
of this work was to contribute with measurements of tree ecosystemsshowedacetoneemiSssicoines.nTcheeosbsceervedhetero- Sciencesce
s s
species from the poorly described tropical vegetation in di- geneous emissions, including reactive VOC sspecies which s
rectcomparisonwiththequitewell-investigated,highlyhet- arenoteasilydetectedbyfluxmeasurements,givereasonto Discussions
erogeneousemissionsfromMediterraneanvegetation.VOC performmorescreeningatleafleveland,whenOeverpossible, O
p p
emissionfromsixteenplantspeciesfromtheMediterranean withintheforestsunderambientconditions. e Ocean Sciencee
n n
areawerecomparedwithtwelveplantspeciesfromdifferent Ocean Science A A
cc Discussions cc
environments of the Amazon basin by an emission screen- e e
s s
ing at leaf level using branch enclosures. Analysis of the s s
volatileorganicswasperformedonlinebyaproton-transfer- 1 Introduction
reaction mass spectrometer (PTR-MS) and offline by col- O O
p p
lection on adsorbent tubes and subsequent gas chromato- Vegetation is the main producer of volatile enorganic com- Solid Earthen
gemraipthteidcafnoallloywsiesd.Isboyprmenoenowtearsptehneems,omstedthoamnionlanatncdoamcpeotounned. pthoeunadtmso(VspOhCer)ea(fAfetcktiinnsgocnheamnSdicoAallrieadyn, dE2p0ah0y3rs)ti.hcaBl AcceiporgoepneicrtiVesOoCf Discussions Acce
s s
The average loss rates of VOC carbon in relation to the regulates the oxidative capacity of the atmospshere and has s
net CO assimilation were found below 4% and indicat- anindirectimpactonthelifetimeofgreenhousegases.Fur-
2
ing normal unstressed plant behavior. Most of the Mediter- thermore, they are involved in the formation aOnd growth of O
p p
ranean species emitted a large variety of monoterpenes, secondaryorganicaerosols(SOA),whichinturennaffectcloud The Cryosphereen
whereasonlyfivetropicalspecieswereidentifiedasmonoter- developmentandpreTciphiteat iConr(yAondsrpeaheeanrdeC Acrutzen,1997; Ac
c Discussions c
pene emitters exhibiting a quite conservative emission pat- Wangetal.,1998;Collinsetal.,2002;Lelievelesdetal.,2002; es
s s
tern(α-pinene<limonene<sabinene<ß-pinene).Mediter- Claeysetal.,2004;Po¨schletal.,2010;Sjostedtetal.,2011).
raneanplantsshowedadditionalemissionsofsesquiterpenes. Emissioninventoriesandmodelcalculationshavebeende-
In the case of Amazonian plants no sesquiterpenes were velopedtodefineregionalandglobalbiogenicVOCemission
detected. However, missing of sesquiterpenes may also be strength,howevertheyrelymostlyonstudiesofVOCemis-
due to a lack of sensitivity of the measuring systems. Fur- sionsfromvegetationfromtemperateareasofNorthAmer-
ica and Europe (Guenther et al., 1995; Kinnee et al., 1997;
PublishedbyCopernicusPublicationsonbehalfoftheEuropeanGeosciencesUnion.
5856 A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds
Simpson,1999;Guentheretal.,2006),oronstudiesofonly 2 Materialandmethods
one VOC species, i.e. isoprene (Lerdau and Keller, 1997;
Lerdau and Throop, 1999, 2000; Harley et al., 2004; Pego- 2.1 Plantmaterialandenvironmentalconditions
raroetal.,2006;Okuetal.,2008;Ferreiraetal.,2010;Misz-
taletal.,2010).Becauseoftheheterogeneityofecoregions, 2.1.1 Tropicalvegetation
species diversity, inaccessibility, and logistical and method-
ological difficulties, the number of investigations made in VOC emission screening was carried out with a total of
tropical regions is limited (Geron et al., 2002; Kesselmeier twelve different tree species common for terra firme and
etal.,2002,2009;Kuhnetal.,2002a,b,2004,2007;Harley floodplain areas in the Amazonas region (Table 1). Three
etal.,2004).Yet,VOCemissionsfromtropicalforestsareof representative tree species were derived from the upland
specialinterestbecausetheircontributiontotheglobalVOC forest (terra firme) ecosystem, eight from the white wa-
budget(estimatedtobe30%)isdisproportionalascompared ter floodplain region (va´rzea) which is regularly inundated
totheirterrestrialareafractionofonly7%(Guentheretal., with nutrient-rich and sediment-loaded “white” water and
1995).Incontrasttothetropics,Mediterraneanplantspecies threefromthe(igapo´)floodplainregionregularlyinundated
havealreadybeenintensivelystudiedandareknowntoemit with nutrient-poor “black” water rich in humic matter, or
agreatvarietyofVOC(Owenetal.,1997;Kesselmeierand clear-waterwithanintermediateamountofnutrients(Prance,
Staudt, 1999; Owen et al., 2001, 2002; Llusia et al., 2002; 1979;Sioli,1954,1956).Twooftheplantspecies,Vatairea
Simonetal.,2006). guianensisandHeveaspruceana,arefoundintheigapo´ and
In general, most of these studies concentrated on the va´rzeaaswell.
emission of isoprene and monoterpenes. Less information The tropical screening experiment was a cooperative ef-
isavailableontheemissionofshort-chainoxygenatedcom- fort between the Max Planck Institute for Chemistry and
pounds(oxVOCs)suchasformaldehyde,acetaldehyde,ace- the Instituto Nacional de Pesquisas da Amazoˆnia (INPA,
tone,methanol,ethanolandformicandaceticacids(Secoet Manaus), and was performed at the INPA Campus forest in
al., 2007). Emissions of these oxygenated compounds were Manaus, Brazil. One- or two-year-old saplings of Garcinia
identified only recently as being a large source of carbon macrophylla,HeveaspruceanaandVataireaguianensisfrom
(150–500TgCyr−1)totheatmosphere(Singhetal.,2001). igapo´, Hura crepitans, Pouteria glomerata, Pseudobombax
Other compounds of high interest are sesquiterpenes (Jar- munguba, Ocotea cymbarum, Pachira insignis, Zygia ju-
dine et al., 2011), but they are not easily measured due to rana,HeveaspruceanaandVataireaguianensisfromva´rzea,
their high reactivity (Fuentes et al., 2000). Sesquiterpenes and Scleronema micranthum, Hevea brasiliensis and He-
and other highly reactive compounds may constitute a con- vea guianensis from terra firme were measured in 2006
siderable amount of the unmeasured VOC (Goldstein et al., and 2007. The terra firme species Hevea brasiliensis, He-
2004) as evidenced by indirect approaches (Di Carlo et al., vea guianensis and Scleronema micranthum were collected
2004;Kuhnetal.,2007). attheReservaDucke,whichissituated40kmfromManaus.
Thepresentstudyaimstocontributetowardsamorecom- 90%oftheReserve’sareaiscoveredbyprimaryvegetation
plete assessment of VOC released at leaf level, contrasting characteristicoftheCentralAmazonterrafirme(Gomesand
fluxstudieswhichmaymissthemorereactiveVOCspecies. Mello-Silva, 2006). The va´rzea species Hevea spruceana,
We chose the Amazonian vegetation because it is a poorly Huracrepitans,Ocoteacymbarum,Pachirainsignis,Poute-
investigatedregionandcompareditwiththemuchbetterde- ria glomerata, Pseudobombax munguba, Vatairea guianen-
scribedMediterraneanecosystemwhichexhibitsaveryhet- sisandZygiajuruanawerecollectedatthebankoftheIlha
erogeneousemissioncomposition.Thisstudywasperformed da Marchantaria (03◦150S, 59◦580W), an island located in
asadoctoralthesis(Bracho-Nunez,2010)whichcanbecon- theSolimo˜esRiver.Theigapo´speciesGarciniamacrophylla,
sulted at the given URL for more details. To enable a com- Hevea spruceana and Vatairea guianensis were collected at
parisonoftheVOCemissionsbetweentropicalandMediter- thebankoftheTaruma˜Mirim(03◦080S,60◦010W)anafflu-
raneanvegetationoverabroadrangeofVOCspecies,several entoftheRioNegro.Effectsofdifferentfloodplainenviron-
different methods for characterization and quantification of mentsontracegasemissionqualityandquantitywereinves-
VOCwereused:aproton-transfer-reactionmassspectrome- tigated comparing plant individuals growing in va´rzea and
ter(PTR-MS)forthedetectionofallVOCwithprotonaffin- igapo´ as well, such as Hevea spruceana and Vatairea guia-
ity higher than water; an online gas-chromatograph with a nensis. Collected plants were potted in soil obtained from
flameionizationdetector(GC-FID)forthedeterminationof thesitesoftheplant’soriginandallowedtoadapttothenew
isoprene emissions; and an offline GC-FID along with an conditions for at least one month before making measure-
offline gas-chromatograph coupled to a mass spectrometer ments.Plantswerekeptundersunlitconditions,protectedby
(GC-MS) for the determination of higher VOC, including mosquitonets,andwereirrigateddaily.Dailymeantempera-
sesquiterpenes. tureconditionsof29◦C±1.6◦Cand27.8◦C±1.3◦Cwere
recorded during the dry and wet season, respectively. A to-
tal of three replicates for each species were measured with
Biogeosciences,10,5855–5873,2013 www.biogeosciences.net/10/5855/2013/
A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds 5857
Table1.Plantspecies,family,functionaltype,ecosystemanddistributionofthe12investigatedtropicalplantspecies.
Plantspecies Family Functionaltype1 Distribution2
Garciniamacrophylla Clusiaceae evergreentree TropicalSouthAmerica,
(Mart.)Planch.&Triana SoutheastAsia,
UnitedStates
Heveabrasiliensis Euphorbiaceae evergreentree TropicalSouthAmerica,
(Willd.ex.A.Juss.) CentralAmerica,
Mu¨ll.Arg. WestAfrica,Central
Africa,Southand
SE Asia, south of North
America
HeveaguianensisAubl. Euphorbiaceae evergreentree TropicalSouthAmerica
Heveaspruceana(Benth.) Euphorbiaceae deciduous/ TropicalSouthAmerica,
Mu¨ll.Arg. brevi-deciduous CentralAmerica
tree
HuracrepitansL. Euphorbiaceae brevi-deciduous TropicalSouthAmerica,
tree CentralAmerica,
WestAfrica,SEAsia,
SouthofNorthAmerica
OcoteacymbarumKunth Lauraceae brevi-deciduous/ TropicalSouthAmerica
evergreentree
Pachirainsignis Malvaceae brevi-deciduous TropicalSouthAmerica,
(Sw.)Sw.exSavigny tree WestAfrica
Pouteriaglomerata Sapotaceae evergreentree TropicalSouthandCentral
(Miq.)Radlk. America
Pseudobombaxmunguba Malvaceae deciduoustree TropicalSouthAmerica
(Mart.&Zucc.)Dugand
Scleronemamicranthum Malvaceae evergreentree TropicalSouthAmerica
Ducke
VataireaguianensisAubl. Fabaceae deciduoustree TropicalSouthAmerica
Zygiajuruana(Harms) Fabaceae evergreentree TropicalSouthAmerica
L.Rico
1(Scho¨ngartetal.,2002).2GlobalBiodiversityInformationFacility:http://data.gbif.organdwww.worldagroforestrycentre.org,(v)
Va´rzea(i)Igapo´
someexceptions(Table7).Plantincubationindynamicflow- 2.2 Enclosuretechniquesandgasexchange
through-enclosures started at 8.00p.m. (local time) on the measurements
evening before measurements were performed the next day
toallowtreeindividualstoadapttotheenclosuresystem. 2.2.1 Tropicalvegetation
2.1.2 Mediterraneanvegetation For the measurement of tropical plants an enclosure sys-
tem developed at the Max Planck Institute for Chemistry
AllplantswerecollectedinMarch2008fromthesurround-
in Mainz, Germany was used. This enclosure system has
ingsofMontpellier,France,andwerepottedandmaintained
been described in detail elsewhere (Scha¨fer et al., 1992;
inagreenhouseoftheinstituteatanapproximateday/night
Kesselmeier et al., 1996; Kuhn et al., 2002a, b). Two iden-
temperature of 25/15◦C. All together a total of sixteen
tical branch cuvettes made of fully light-permeable FEP
plant species (all 2–3yr old) including deciduous and non-
Teflon foil (Norton, 50µm thickness, Saint-Gobain Perfor-
deciduous trees, shrubs, grasses and palm trees typical for
mancePlastics,Germany)wereflushedwithozone-freeam-
the Mediterranean area were studied at the CEFE-CNRS in
bientair.Onecuvettewasusedasthereference“empty”cu-
Montpellier(France)duringthemonthsofApriltoJuly2008
vetteandasecondcuvetteenclosedabranchorthecomplete
(Table2).Again,foreachspeciestherewerethreereplicates.
plantaboveground.Ambientairwasscrubbedofsmallparti-
clesusingTeflonfilters(ZefluorTeflonfilters,2µmporesize,
GelmanScience,USA)andofozonewithanozonescrubber
composed by ten copper nets coated with MnO (Ansyco,
2
Germany) placed in a Teflon tube to prevent oxidant inter-
www.biogeosciences.net/10/5855/2013/ Biogeosciences,10,5855–5873,2013
5858 A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds
Table2.Plantspecies,family,functionaltypeandoccurrenceofthe16investigatedMediterraneanplantspecies.
Plantspecies Family Functionaltype Distribution
BrachypodiumretusumPers. Poaceae evergreenherb Mediterraneanregion
BuxussempervirensL. Buxaceae evergreenshrub westernandsouthern
Europe,
northwestAfrica,
southwestAsia
CeratoniasiliquaL. Fabaceae evergreentree Mediterraneanregion
Chamaeropshumilis(L.)Cav. Arecaceae palmtree westernMediterranean
region
CistusalbidusL. Cistaceae evergreenshrub southwestEuropeto
NorthAfrica,
Mediterraneanregion
CistusmonspeliensisL. Cistaceae evergreenshrub southwestEurope
CoronillavalentinaPall.exBieb. Fabaceae evergreenshrub Mediterraneanregion
FicuscaricaL. Moraceae deciduoustree southwestAsiaandthe
easternMediterranean
region
OleaeuropaeaL. Oleaceae evergreentree Coastalareasofeastern
Mediterraneanregion
andAsiaMinor;
southernregionofthe
CaspianSea
PinushalepensisMill. Pinaceae evergreentree Mediterraneanregion
Prunuspersica(L.)Batsch. Rosaceae deciduoustree China, Iran, Mediterranean
region
QuercusafaresPomel Fagaceae deciduoustree AlgeriaandTunisia
QuercuscocciferaL. Fagaceae evergreentree westernMediterranean
region,
Morocco,Portugal,
easternGreece
QuercussuberL. Fagaceae evergreentree southwestEurope,
northwestAfrica
RosmarinusofficinalisL. Lamiaceae evergreenherb Mediterraneanregion
SpartiumjunceumL. Fabaceae evergreenshrub Mediterraneanregion
ferencesinsidetheenclosure.AcombinationofthreeTeflon ambient temperature in order to avoid condensation in the
membranepumps(Vacuubrand,Germany)wasusedtopump lines.
thefilteredambientairtobothcuvettes.Theairflowtoeach CO andH OexchangeweremeasuredwithaCO /H O
2 2 2 2
cuvette was monitored by an in-line flow meter (EL-Flow, infraredgasanalyzer(LI-CORInc.7000,Lincoln,Nebraska,
50Lmin−1,BronkhorstHi-Tec,Germany).Twodifferentcu- USA). The analyzer was operated in differential mode re-
vettesizeswithvolumesof9Land100Lwereuseddepend- ceiving an analog signal of the absolute concentration mea-
ingonthesizeoftheplanttobeenclosed.Thecuvetteflow suredbyasecondCO /H Oinfraredgasanalyzer(LI-COR
2 2
wascontrolledbyaneedlevalveandadjustedto10Lmin−1 Inc. 7000, Lincoln, Nebraska, USA) as reference. Pressur-
forthesmallcuvetteandto20–40Lmin−1 forthelargercu- izednitrogengas(N 5.0,MesserGriesheim,Germany)was
2
vette. used as the reference gas for the CO and H O zero-point
2 2
Mixing of air within the cuvette was achieved with a calibrationoftheinfraredgasanalyzers.Thegasflowtothe
Teflon-coated fan. Cuvette temperature and relative humid- instrumentwassuppliedbyacustom-madepumpunit(mem-
ity was measured in bypassed air with a commercial sen- brane pump, 12 Volt; KNF-NEUBERGER, Freiburg, Ger-
sor(ModelRotronicsYA-100F,Walz,Germany).Exchange many) and adjusted to 0.5Lmin−1 by a rotameter (Omega,
of VOC, CO and H O was monitored by direct sampling USA). Calibration of the analyzer was accomplished prior
2, 2
from the sample and reference cuvette. All sample tubing to the experiments by use of a calibration gas standard for
was made of Teflon and maintained at a constant tempera- the calibration of CO (512±2ppm CO in synthetic air,
2 2
ture of 45◦C, which was always higher than the cuvette or LI-COR, Lincoln, Nebraska, USA) and a dew point gener-
ator for the calibration of water channel (Li 610; LI-COR,
Biogeosciences,10,5855–5873,2013 www.biogeosciences.net/10/5855/2013/
A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds 5859
Table3.Leaftemperature(Tleaf)andphotosyntheticactiveradia- vette at different heights before and after the measurements
tion(PAR)oftropicalplantsmeasuredundersemi-controlledcon- andfoundtobehomogeneousfortheareaofthewholeen-
ditions.Enclosuretemperatureswerenotsignificantlydifferentas closed plant. The irradiation value determined in the center
◦
comparedtoleaftemperatureswith1 Clowermeantemperatures ofthecuvettewastakenastheincidentPAR.Inthecourseof
at most. Averages ± standard deviation of measurements with n
allothergasexchangemeasurementsthesamesensorwasin-
treeindividuals.Eachreplicaterepresentsanaverageofdatapoints
stallednexttothechambersystem.Lightintensitiesandthe
measured every minute during one day measurement by a PAR
<300µmolm−2s−1 (this PAR value was determined with light cuvetteandleaftemperaturesmeasuredwiththermocouples
oftypeE(Chrom-Constantan,OMEGA)wererecordedwith
curves (data not shown) and represents the photosynthetic satura-
a data logger CR23X (Campbell Scientific Ltd., Shepsherd,
tionpointofalltropicalplants).
UK). All other micrometeorological and physiological pa-
rametersweremonitoredandrecordedwithain-housecon-
Tleaf PAR
n [◦C] [µmolm−2s−1] trol unit (V25, Max-Planck Institute for Chemistry, Mainz,
Germany).
Garciniamacrophylla 3 36±2 1259±61
Heveabrasiliensis 3 34±2 502±4
2.2.2 Mediterraneanvegetation
Heveaguianensis 2 34±1 499±1
Heveaspruceana(v) 2 33±1 498±3
Gas exchange of Mediterranean vegetation was measured
Heveaspruceana(i) 3 35±2 1329±138
Huracrepitans 3 32±1 794±92 using a dynamic temperature- and light-controlled chamber
Ocoteacymbarum 3 32±2 607±13 system(Staudtetal.,2004;Bracho-Nunezetal.,2011).This
Pachirainsignis 3 31±1 595±11 custom-made gas exchange chamber with a volume of ap-
Pouteriaglomerata 3 32±1 573±3 proximately105mLwasconstantlyflushedwithairataflow
Pseudobombaxmunguba 3 33±2 1171±309 of650mLmin−1.Theairwaspurifiedanddriedbyaclean
Scleronemamicranthum 3 33±1 607±15 airgenerator(AIRMOPURE,Chromatotec,France)andthen
Vataireaguianensis(v) 2 31±1 497±1 re-humidifiedbypassingavariableportionoftheairstream
Vataireaguianensis(i) 2 33±1 499±2
throughawaterbubbler.AlltubingwasmadeofTeflonand
Zygiajurana 3 32±1 612±3
sample lines were maintained at a constant temperature of
(v)va´rzea,(i)igapo´ 45◦C.Chamberandplantswereilluminatedwithwhitelight
(OSRAM 1000W) filtered by a 5cm water bath. PAR was
measuredwithaquantumsensor(LiCor,PAR-SB190,Lin-
Lincoln, Nebraska, USA). At the end of each experiment coln, NE, USA) located next to the chamber system. Leaf
the calibration of the analyzer was checked and the signal andchamberairtemperaturesweremonitoredwithtwother-
response was corrected for sensitivity and zero drifts as a mocouplesoftypeE(Chrom-Constantan,OMEGA).Forall
function of time and temperature. Assimilation, transpira- measurementsofMediterraneanvegetation,temperatureand
tionandstomatalconductancewerecalculatedaccordingto light was kept constant at standard conditions (leaf temper-
Pearcyetal.(1989). ature=30±1◦CandPAR=1055±36µmolm−2s−1).Rel-
All measurements of tropical vegetation were performed ative humidity was also maintained constant at 48±13%.
undersemi-controlledconditionsfollowingambientrelative All data were stored on a 21X data logger (Campbell Sci-
humidity, temperature and CO . Relative humidity ranged entific Ltd., Shepsherd, UK). Photosynthesis and transpira-
2
between77±9%and91±7%duringthedryandwetsea- tion were measured by directing a constant portion of the
sonandambientCO concentrationswerefoundintherange inlet and outlet air through a CO /H O infrared gas ana-
2 2 2
of 340–404ppm. Leaf temperatures varied between 31 to lyzer (LI-COR Inc. 7000, Lincoln, Nebraska, USA). Am-
36◦C (Table 3). Garcinia macrophylla, Hevea spruceana bient CO concentrations varied between 318 and 380ppm
2
(igapo´),Huracrepitans,andPseudobombaxmungubawere duringtheexperiments.
measured under ambient light conditions (Table 3). For re- Forthemeasurements,oneorseveralterminalleavesofan
mainingplantspeciesadditionalphotosyntheticactiveradia- individualplantwereplacedperpendiculartothelighttoen-
tion(PAR)wasconstantlyprovidedbyanLEDsystemcon- surehomogenouslightdistributionontheadaxialsurfaceof
sisting of four double chains of a mixture of red, blue and theleaves.Formostoftheplants,itwasnecessarytoremove
white light constructed and designed by the electronics de- someleavestoenableproperplacementinthechamber;this
partmentoftheMPIforChemistryinMainz,Germany.This wasdoneatleastoneweekbeforeanymeasurementstomini-
LEDsystemwasplacedperpendiculartothecuvetteandsup- mizedisturbanceeffects.Inordertoensureadaptationofthe
portedaconstantlightregimearound500µmolm−2s−1(Ta- plants to the chamber environment, all species were placed
ble 3). Gaps between the LED groups were closed with re- inthechamberatleast1hbeforethemeasurements,oruntil
flectingfilminordertoobtainahomogenousdistributionof the VOC signals measured with PTR-MS were found con-
thelightinthecuvette.Theirradiationwasmonitoredwitha stant. Leaves of the conifer Pinus halepensis and the aro-
quantumsensor(ModelSB190,LiCor,USA)insidethecu- maticshrubRosmarinusofficinalispossessglandsandducts
www.biogeosciences.net/10/5855/2013/ Biogeosciences,10,5855–5873,2013
5860 A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds
which store VOC. It has been shown that mechanical stress plechamber,takingintoaccounttencyclesofthereference
can cause large bursts of VOC from these plants, leading and sample chamber, each. The instrument background sig-
to large overestimations of VOC emission rates normalized nals were determined with air samples after passing over a
asstandardemissions(E )at30◦Cand1000µmolm−2s−1 heated platinum catalyst maintained at 350◦C (Parker Co.,
s
(PAR) (Niinemets et al., 2011). Therefore, as based on our USA).Thebackgroundsignalwassubtractedfromtherefer-
experiencesduringpreviouswork,theleavesofthesespecies ence and sample chamber signals. This procedure was re-
wereenclosedatleast12hbeforemakingmeasurements. peated from 8.00p.m. to 6.00p.m. of the following day.
For VOC emission rate calculations the reference chamber
2.3 VOCmeasurements signals (with background subtracted) were subtracted from
the sample chamber signals (with background subtracted).
2.3.1 GCtechniques Mediterranean vegetation screening by PTR-MS measure-
ments were performed similarly as described above with a
VOCemissionsfromtropicalvegetationweremeasuredus- slightlychangedsamplingprotocol.Tencyclesofenclosure
ing two different methods, (i) by collection on cartridges measurements switching between sample and empty refer-
using an automatic sampler, and subsequent analysis with ence cuvette were followed by three cycles of instrument
anofflinegaschromatographic(GC)methodequippedwith background measurements. This process was repeated 3 to
a flame ionization detector (FID; Kesselmeier et al., 2002; 10times.
Kuhn et al., 2002b) in the MPIC laboratory in Mainz, Ger- The PTR-MS instrument was calibrated using a VOC
many; and (ii) by online PTR-MS as described below. In standard mixture in nitrogen (Deuste Steininger GmbH,
the case of Mediterranean vegetation three GC-instruments Germany) containing some target VOCs (isoprene, α-
were used: an AirmoVOC C2-C6 online GC-FID (Chroma- pinene, methanol and acetone) at concentrations of
totec, France) for the detection of isoprene and apolar light 300nmolmol−1±10%. For calibration, the gas was fur-
VOCs,aChrompackCP9003offlineGC-FIDequippedwith ther diluted with synthetic air to final concentrations of
aChrompackTCT4002thermo-desorber(allVarianInc.)for 0.5–10nmolmol−1.Forthequantificationofsesquiterpenes
the detection of higher VOCs such as monoterpenes and a calculation of simple ion-molecule reaction kinetics was
sesquiterpenes, and a Varian CP3800/Saturn2000 GC-MS used as described elsewhere (Hansel et al., 1995; Wisthaler
equippedwithaPerkin-ElmerTurbomatrixthermo-desorber et al., 2001). Since the quantification of monoterpenes
toconfirmPTR-MSsignalsbyrelatedGCpeaks.Adetailed and sesquiterpenes with the PTR-MS is usually very diffi-
descriptionoftheGCsystemsisreportedbyBracho-Nunez cult due to their tendency to fragment into different com-
etal.(2011). pounds depending on the VOC species (Tani et al., 2003;
Demarckeetal.,2009), these data were always comple-
2.3.2 PTR-MStechniques mentedbyGC-FIDorGC-MS(Bracho-Nunezetal.,2011).
The detection limit of the PTR-MS was estimated as being
For real-time VOC monitoring, the PTR-MS (Ionicon An- 1.96timesthestandarddeviationoftheemptychambercon-
alytik, Austria) was operated in selected ion-monitoring centrations (at the 95% confidence level) and was typically
mode at standard operational settings (E/N=130Td; 1.6nmolmol−1 for methanol, 579pmolmol−1 for acetone,
E electric field strength, N buffer gas number density, 493pmolmol−1 for isoprene, 201pmolmol−1 for monoter-
1Td=10−17cm2Vmol−1)atadrifttubevoltageof600V. penes,and94pmolmol−1 forsesquiterpenes,andthedetec-
A total of 27 mass signals (protonated masses, i.e. Molec- tionlimitsoftheGCsrangedbetween0.1and0.4ngL−1.
ular Weight + 1) were measured by the PTR-MS with a
dwell time of 1s: m21, m29, m31, m32, m33, m39, m42, 2.4 Leafareaanddryweightdetermination
m45, m47, m55, m59, m61, m69, m71, m73, m75, m81,
m83, m87, m93, m95, m107, m121, m137, m139, m151, Projected leaf areas were determined either with an optical
m205.Themeasurementofonecompletecycletook27sec- area meter (Delta-T Devices Ltd., Cambridge, UK) or by
onds. The main compounds detected from tropical vegeta- copying the shape of the measured leaves on a sheet that
tion were methanol (m33), acetone (m59), isoprene (m69), was subsequently scanned using the software Size (Version
andmonoterpenes(m137,fragmentonm81).Mediterranean 1.10R, Mu¨ller-Software) (Kesselmeier et al., 1996). To ob-
vegetationshowedemissionsofthesamecompoundclasses tain leaf dry weights, leaves were dried at 60◦C for at least
and additional emissions of sesquiterpenes (m205). Differ- 48hbeforeweighing.Errorswereestimatedat0.2%and2%
entisomersofmonoterpenesorsesquiterpenescannotbedis- fordryweightandleafareadetermination,respectively.
tinguishedwithaPTR-MS,thereforePTR-MSbasedE for
s
monoterpenesandsesquiterpenesalwaysreferstothesumof 2.5 Datatreatments
allmonoterpenesandsesquiterpenes,respectively.
In the case of tropical vegetation screening, the PTR- The emission rate E [µgg−1h−1] of each compound
s
MS probing switched between the reference and the sam- was calculated according to Eq. (1) based on the
Biogeosciences,10,5855–5873,2013 www.biogeosciences.net/10/5855/2013/
A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds 5861
measured concentration difference (1c=c − amountofVOCemissionsofthetenemitters,eightspecies
sample chamber
−c )in[nmolL−1],thechamberflush were identified as high emitters (<10µgg−1h−1) and two
empty or reference chamber
rate Q in [Lh−1], the leaf dry weight (dw) in [g] and the species, Scleronema micranthum and Hevea guianensis, as
molecularmassM in[gmol−1]. lowtomoderateemitters(1–10µgg−1h−1).Itisimportantto
notethatsaplingswereinvestigated.Mature,naturallygrow-
(cid:18) (cid:19)
E =1c Q ×M×10−3 (1) ing plants may exhibit other emission qualities and quan-
s
dw tities. However, their investigation in the field is difficult.
Therefore, our screening results may be regarded as a first
ForVOCemissionsmeasuredundernonstandardlightand
stepaddingtoourcurrentknowledge.
temperatureconditions(theconditionsformostofthemea-
All isoprene-emitting plant species were high emitters
surements on tropical species, Table 3), the phenomenolog- (<10µgg−1h−1) (Table 4). Four plant species were found
icalalgorithmdescribedbyGuentheretal.(1993)wasused
to emit monoterpenes (Table 4). Only slight differences
to standardize the actual VOC emission rates to standard
were found comparing one and the same species derived
emission rates, often referred to as the basal emission rate.
from va´rzea and igapo´, i.e. Hevea spruceana and Vatairea
This algorithm describes the light and temperature depen-
guianensis. The relatively conservative composition of the
dencies for VOC originating from DMAPP (Dimethylallyl
monoterpenes emitted by all monoterpene-emitting tropical
pyrophosphate),suchasisopreneandmonoterpenesanddis-
plantspeciesstudiedwassimilarwithα-pineneasthemost
tinguishes between emissions from VOC storage pools and
abundantmonoterpenefollowedbylimonene,sabineneorβ-
newly synthesized VOC. Since acetone and methanol also
pineneandothermonoterpenes,exceptforHeveaguianensis
showedlightandtemperaturedependencyduringthisstudy,
thatemittedonlyα-pineneandcamphene(Table5).Itisin-
emission rates of these compounds could also be described
teresting to see all Hevea species investigated so far being
withthisalgorithm.Methanolemissiondependsonstomatal
identified as monoterpene emitters in close agreement with
conductance and accumulation occurs in the stomatal cavi-
earlierreportsaboutHeveabrasiliensis(Klingeretal.,2002;
tiesduringnight.Thus,inthemorningamethanolpeakwas
Bakeretal.,2005).
detected on some occasions, due to the burst of the noctur-
In addition to isoprenoid emissions a release of oxy-
nallyaccumulatedmethanolafterstomatalopening.Though
genated VOCs, methanol and acetone, was found with sev-
thisburstcanreachhigheremissionratevaluesthanobserved
eral of the investigated plant species. Methanol emissions
duringtherestoftheday,itdoesnotdominatethedailyemis-
were detected in the case of seven species with emis-
sionsasitlastsonlyashorttime.Nevertheless,itcouldaffect sion rates varying between 1.5 to 20.2µgg−1h−1 (Ta-
thedeterminationofE derivedfromlinearregressionanal-
s ble 4). Low emissions of acetone could be detected in the
ysis according to the corresponding algorithm (Guenther et
case of Hevea spruceana originating from both ecosystems
al.,1993).Therefore,thismorningpeakwasexcludedforthe (<1.5µgg−1h−1).
calculationofE .OurstrategyimpliesthattheVOCemitted
s A noticeable release of mass 73 was detected from
from the tropical plants were de-novo-synthesized without
Garcina macrophylla during daytime conditions (light).
substantial storage after production. This assumption could
Mass73mayberegardedastheprotonatedmethylethylke-
be confirmed by the absence of VOC emissions in the dark
tone (MEK), an oxidation product of isoprene. This inter-
evenatelevatedtemperatures.
pretationwouldbeinaccordancewiththehighemissionsof
isoprenefoundforthisplant.Furthermore,productionwithin
2.6 Statistics
plants can no longer be excluded (Jardine et al., 2013). But
other compounds, such as methylglyoxal (Holzinger et al.,
One-way Anova tests were carried out in order to de-
2007)or2-methylpropanal(Jardineetal.,2010)couldalso
tect possible differences among two or more independent
bemaderesponsibleforthismass.
groups. Mean VOC emissions (methanol, acetone, isoprene
or monoterpenes separately) from tropical plant species
3.2 ScreeningMediterraneanvegetation
were tested against those emitted from Mediterranean plant
species and the same species from different ecosystems
As in the case of tropical plants, the Mediterranean plants
(igapo´ vs.va´rzea).Thestatisticallysignificantdifferenceef-
investigated were also saplings showing emission rates that
fectinANOVAwasprovenbytheTukey’stest.
may differ as compared to mature, naturally growing indi-
viduals.AllsixteenMediterraneanplantspeciesinvestigated
werefoundtoemitVOC,nineofwhichbeinghighemitters
3 Results
(11.0–69.1µgg−1h−1), whereas the rest of the plants were
3.1 ScreeningTropicalvegetation moderate emitters, showing VOC emissions in the range of
2.6and9.3µgg−1h−1(Table4).
In ten out of twelve plant species screened, we were able Most of the Mediterranean plants emitted isoprene.
to observe VOC emissions (Table 4). Considering the total Five of them could be classified as high emitters (E
s
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5862 A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds
Table4.VOCemitteda fromMediterraneanandtropicalplantspeciesmeasuredwithPTR-MS(Exceptforsesquiterpeneemissionsfrom
Buxus sempervirens, Ceratonia siliqua and Olea europaea that were only detected with GC-FID). All averages ± standard errors are
calculatedfrom<100samples(tropical)or18–83samples(Mediterranean)fromntreeindividuals.
Isoprene Monoterpenes Sesquiterpenes Methanol Acetone m/z73
n [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1]
Tropicalplantspecies
Garciniamacrophylla 3 16.83±3.45 – – 1.86±0.06 – 1.77±0.93
Heveabrasiliensis 3 – 21.33±14.66 – 2.20±0.15 – –
Heveaguianensis 2 – 9.45±1.63 – – – –
Heveaspruceana(v) 2 – 18.90±16.26 – – 1.4±0.1 –
Heveaspruceana(i) 3 – 52.50±13.35 – – 0.66±0.32 –
Huracrepitans 3 – – – 20.16±0.38 – –
Ocoteacymbarum 3 – – – – – –
Pachirainsignis 3 12.13±3.84 – – 4.00±0.06 – –
Pouteriaglomerata 3 – – – – – –
Pseudobombaxmunguba 3 – – – 13.53±0.2 – –
Scleronemamicranthum 3 – 0.35±0.07 – 1.53±0.03 – –
Vataireaguianensis(v) 2 63.20±42.85 – – 6.05±0.07 – –
Vataireaguianensis(i) 2 47.20±3.53 – – 2.30±0.42 – –
Zygiajurana 3 13.73±8.78 – – – – –
Mediterraneanplantspecies
Brachypodiumretusum 3 56.18±20 1.1±0.71 – 5.48±1.99 1.77±1.62 –
Buxussempervirens 3 21.46±5.21 0.13±0.06 0.07±0.05 1.04±0.63 – –
Ceratoniasiliqua 3 0.52±0.17 7.94±5.41 0.03±0.02 0.79±0.23 – –
Chamaeropshumilis 3 18.93±3.44 0.14±0.03 – – – –
Cistusalbidus 3 – 0.3±0.07 0.63±0.32 8.2±4.61 – –
Cistusmonspeliensis 3 – 1.03±0.49 0.6±0.18 7.46±5.2 – –
Coronillavalentina 3 0.43±0.08 0.75±0.45 – 13.48±7.84 0.61±0.07 –
Ficuscarica 3 60.75±4.79 – – 4.22±2.15 4.17±1.18 –
Oleaeuropea 3 0.12±0.09 1.21±0.95 0.09±0.01 1.03±0.2 0.11±0.02 –
Pinushalepensis 3 0.1±0.07 2.75±0.94 – 2.95±0.09 0.09±0.01 –
Prunuspersica 3 0.04±0.03 0.36±0.25 – 4,01±1.3 0.32±0.18 –
Quercusafares 2 0.88±0.61 16.18±10.13 – 1.27±0.4 – –
Quercuscoccifera 3 0.64±0.23 5.77±6.42 0.24±0.13 4.11±3.9 0.25±0.09 –
Quercussuber 3 0.26±0.09 35.58±5.46 – 1.83±1.1 – –
Rosmarinusofficinalis 3 – 1.97±1.36 – 2.03±0.61 – –
Spartiumjunceum 3 28.28±6.13 – – 3.74±0.72 – –
aNormalizedtostandardconditions(PAR:1000µmolm−2s−1andleaftemperature:30◦C)withRasaconstant(=8.314JK−1mol−1)andtheempiricalcoefficientsa
(=0.0027),CL1(=1.066),CT,(=95000Jmol−1),CT2(=230000Jmol−1),CT3(=0.961)andTM(=314K)accordingtoGuentheretal.(1993)andGuenther(1997),(i)
igapo´,(v)va´rzea.
<10µgg−1h−1) and the other eight as low emitters (E tively,themassesclassifiedasmonoterpene(m81andm137)
s
<1µgg−1 h−1)(Table4).Fourteenoutofthesixteeninves- byPTR-MSmightberelatedtootherVOCspecies.Forex-
tigated Mediterranean plants emitted monoterpenes in sig- ample, interferences of sesquiterpene fragments like (−)E-
nificant amounts (Table 4). Nine of them were classified caryophyllene(m81)andα-humulene(m137)havebeenre-
as moderate to high monoterpene emitters with emissions ported to potentially contribute 7.5 and 6% for each mass
rangingbetween1and36µgg−1h−1.Furthermore,PTR-MS (Demarckeetal.,2009).
measurementsalsoindicatedlowmonoterpeneemissionsfor The monoterpene composition of the emissions from
Chamaeropshumilis,Cistusalbidus,Coronillavalentinaand Mediterranean vegetation was highly species specific and
Prunus persica (<1µgg−1h−1). However this could not veryvariableamongtheplantspecies,assummarizedinTa-
be confirmed by GC analysis. This discrepancy might have ble 5. It should be noted that Mediterranean plants showed
been caused by decomposition of more labile monoterpene up to 14 different monoterpene species. Furthermore, the
species, an artifact of cartridge sampling for GC analysis, variabilityofmonoterpenespeciesamongthedifferentplant
or by the emission of many different monoterpene species specieswasveryhighascomparedtotropicalvegetation.
at rates below the detection limit for GC analysis. Alterna-
Biogeosciences,10,5855–5873,2013 www.biogeosciences.net/10/5855/2013/
A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds 5863
Table 5. Monoterpene species emitteda from Mediterranean and tropical plant species measured with GC-FID. All averages ± standard
errorsarecalculatedfrom<100samples(tropical)or18–83samples(Mediterranean)fromntreeindividuals.OthersincludeinP.halepensis
(terpinene-4-ol),inQ.afares(linaloolandallo-ocimene),inQ.coccifera(α-thujene,ß-phellandrene,eucalyptolandα-terpinene),inQ.suber
(α-thujene,menthol,terpinolene,o-cymene,terpinene-4-ol,cis-sabinenehydrate,borneolandα-terpinene),inR.officinalis(eucalyptoland
camphor)inH.spruceana(i)(3-carene),inH.spruceana(v)(3-carene).
α−pinene limonene sabinene ß-pinene camphene p-cymene myrcene γ-terpinene α-phellandrene Z-ocimene E-ocimene others
n [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1]
Tropicalplantspecies
Heveaguianensis 2 6.89±4.87 – – – 0.75±0.51 – – – – – – –
Heveabrasiliensis 3 15.03±24.5 4.34±7.52 7.94±4.9 1.38±0.78 0.54±0.8 4.49±4.0 1.05±0.8 2.40±2.24 0.81±0.60 – – 0.72±0.84
Scleronemamicranthum 3 0.27±0.03 0.20±0.13 0.07±0.04 0.12±0.04 – – 0.03±0.02 0.02±0.01 – – – –
Heveaspruceana(v) 3 22.38±3.38 5.9±1.61 2.34±0.88 0.80±0.01 0.84±0.12 1.29±0.91 0.45±0.35 0.44±0.27 – – – 0.04±0.03
Heveaspruceana(i) 3 34.00±7.70 5.81±2.20 4.59±3.80 1.83±0.80 1.58±0.50 3.94±3.19 0.65±0.3 2.06±0.90 0.34±0.26 – – 0.04±0.01
Mediterraneanplantspecies
Buxussempervirens 3 – – – – – – – – 0.12±0.04 – 0.004±0.0004 –
Ceratoniasiliqua 3 – – – – – – 0.06±0.02 – – 1.66±1.30 7.08±5.80 –
Cistusmonspeliensis 3 0.11±0.09 – – 0.06±0.05 0.01±0.009 - 0.03±0.02 – – – 0.03±0.01 –
Oleaeuropea 3 – – – – – – – – – 0.16±0.24 1.48±2.35 -
Pinushalepensis 3 – – – – – – 0.11±0.16 – – 0.05±0.03 2.23±2.17 0.01±0.009
Quercusafares 2 0.07±0.07 3.74±2.84 0.07±0.08 0.09±0.03 – – 0.36±0.17 – – 2.38±2.11 4.12±1.73 0.12±0.12
Quercuscoccifera 3 0.62±0.62 0.72±1.09 0.43±0.50 0.32±0.30 0.007±0.008 0.01±0.003 3.77±6.60 0.02±0.01 1.20±1.60 – – 0.80±1.14
Quercussuber 3 15.04±1.89 0.67±0.07 17.13±2.90 10.93±1.50 0.44±0.06 – 1.35±0.38 0.01±0.01 – – 0.007 0.76±0.10
Rosmarinusofficinalis 1b 0.02 0.20 – 0.07 0.03 – 0.07 – – – – 0.12
aNormalizedtostandardconditions(PAR:1000µmolm−2s−1andleaftemperature:30◦C;Guentheretal.,1993;Guenther,1997),bDuetotechnicalreasonsonlydata
fromoneindividualplantareavailable.
Table6.SesquiterpenespeciesemittedafromMediterraneanandtropicalplantspeciesmeasuredwithGC-FID.Averages±standarderrors
arecalculatedfromnnumberofreplicates.Allaverages±standarderrorsarecalculatedfrom<100samples(tropical)or18–83samples
(Mediterranean)fromntreeindividuals.
(−)E-caryophyllene α-humulene α-copaene ß-copaene α-cubebene ß-cubebene δ-cadinene ß-Bourboubene E-ß-farnesene germacreneD
n [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1] [µgg−1h−1]
Tropicalplantspecies
Heveaguianensis 2 – – – – – – – – – –
Heveabrasiliensis 3 – – – – – – – – – –
Scleronemamicranthum 3 – – – – – – – – – –
Heveaspruceana(v) 3 – – – – – – – – – –
Heveaspruceana(i) 3 – – – – – – – – – –
Mediterraneanplantspecies
Buxussempervirens 3 0.02±0.01 0.05±0.03 – – – – – – – –
Ceratoniasiliqua 3 0.03±0.02 – – – – – – – – –
Cistusalbidus – 0.11±0.06 – 0.02±0.02 0.01±0.01 0.04±0.004 0.06±0.02 0.02±0.02 0.02±0.02 0.04±0.03 –
Cistusmonspeliensis 3 0.20±0.14 – – – – – – – – –
Oleaeuropea 3 0.09±0.01 – – – – – – – – 0.02±0.01
Pinushalepensis 3 – – – – – – – – – –
Quercusafares 2 – – – – – – – – – –
Quercuscoccifera 3 0.10±0.09 – – – 0.01±0.01 – – 0.02±0.02 – –
Quercussuber 3 – – – – – – – – – –
Rosmarinusofficinalis 1b – – – – – – – – – –
aNormalizedtostandardconditions(PAR:1000µmolm−2s−1andleaftemperature:30◦C;Guentheretal.,1993;Guenther,1997);bDuetotechnicalreasonsonlydatafrom
oneindividualplantareavailable;(i)igapo´,(v)va´rzea.
Low emissions of sesquiterpenes (0.1–1.0µgg−1h−1) were also observed. All investigated plant species ex-
werefoundinthecaseofCistusalbidus,Cistusmonspelien- cept Chamaerops humilis emitted methanol (Table 4). The
sis and Quercus coccifera (Table 4). In the case of Buxus range of emission rates was very large (between 1 and
sempervirens,Ceratoniasiliqua andOleaeuropaeatracesof 14µgg−1h−1). For some species low acetone emissions
thoseterpenoids(<0.1µgg−1h−1)wereobserved,butonly were detected (Table 4). Most of these emission rates were
detectable by GC-FID, indicating that the GC-FID method <1µgg−1h−1,exceptforBrachypodiumretusumandFicus
may be more sensitive for these compounds than the PTR- carica.
MS.(−)E-caryophyllenewasthemostfrequentlyoccurring
sesquiterpene species except for Buxus sempervirens, and 3.3 ComparisonofVOCemissionsfromtropicaland
wasthesolecompoundemittedinthecaseofCeratoniasili- Mediterraneanplantspecies
qua and Cistus monspeliensis (Table 6). A great variety of
sesquiterpene species were found in the case of Cistus al- Most of the investigated tropical and Mediterranean plants
bidus. A total of eight different sesquiterpene species were exhibited substantial VOC emissions. Of striking differ-
detected(Table6). ence was the higher number of monoterpene emitters in
Not only isoprenoids were emitted from Mediterranean the case of the Mediterranean vegetation. Only four out
plants. Oxygenated VOC such as methanol and acetone of eight tropical plant species were emitting monoterpenes.
In contrast, monoterpenes dominated emissions in 14 out
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5864 A.Bracho-Nunezetal.: Leaflevelemissionsofvolatileorganiccompounds
Table7.Specificleafweight(SLW),netphotosyntheticrate(NPR),transpiration(E),andstomatalconductance(gs)forMediterraneanand
tropicalplantspecies.Carbonloss(VOCcarboninrelationnetCO2assimilation)isestimatedfromthemeanvaluesofNPS(thistable)and
thesumofVOCcarbonderivedfromthespecieslistedinTable4.ExceptforSLW,allaverages±standarderrorsarecalculatedfrom<100
samples(tropical)or5–125samples(Mediterranean)fromntreeindividuals.
SLW NPR E gs Carbonloss
n [gm−2] [µmolm−2s−1] [mmolm−2s−1] [mms−1] %
Tropicalplantspecies
Garciniamacrophylla 3 142 1.76±0.55 1.55±0.25 1.94±1.50 3.2
Heveabrasiliensis 3 33.4 5.53±3.03 1.53±0.32 3.97±3.35 0.3
Heveaguianensis 2 39.6 2.35±0.07 4±1.27 6.35±1.63 0.3
Heveaspruceana(v) 2 23.6 4.34±0.46 0.80±0.21 1.71±0.31 0.2
Heveaspruceana(i) 3 42.9 7.20±1.33 21.17±4.15 18.92±7.66 0.6
Huracrepitans 3 45.2 8.19±1.09 2.39±0.44 4.86±0.78 0.1
Ocoteacymbarum 3 76.0 4.57±1.10 2.23±0.51 4.87±3.16 –
Pachirainsignis 3 46.0 2.63±0.15 1.03±0.15 0.77±0.90 0.5
Pouteriaglomerata 3 67.7 4.74±0.87 8.93±2.83 17.93±4.97 –
Pseudobombaxmunguba 3 65.0 4.71±0.92 2.07±0.58 2.39±0.74 0.2
Scleronemamicranthum 3 76.9 3.03±0.38 0.87±0.21 1.37±0.23 0.1
Vataireaguianensis(v) 2 26.1 6.61±0.92 1.04±0.55 4.68±1.23 0.5
Vataireaguianensis(i) 2 36.4 3.50±0.70 1.42±0.60 3.73±1.53 1.0
Zygiajurana 3 41.9 3.70±1.40 1.40±0.65 3.47±1.89 0.3
Mediterraneanplantspecies
Brachypodiumretusum 3 85 6.16±2.26 4.81±2.91 10.69±9.15 1.7
Buxussempervirens 3 291 7.97±0.82 2.83±0.65 1.78±0.46 1.6
Ceratoniasiliqua 3 149 3.34±0.66 1.01±0.16 0.95±0.17 0.8
Chamaeropshumilis 3 240 10.21±5.35 3.12±2.35 6.90±4.96 0.9
Cistusalbidus 3 91 12.46±5.43 5.92±1.73 14.66±5.39 0.1
Cistusmonspeliensis 3 110 22.97±7.19 9.40±3.58 20.61±3.79 <0.05
Coronillavalentina 3 73 14.99±4.26 3.64±1.65 4,13±1.91 0.1
Ficuscarica 3 66 8.89±1.14 3.65±0.98 11.91±5.43 1.0
Oleaeuropea 3 352 13.76±1.76 3.69±0.57 5.09±1.28 0.1
Pinushalepensis 3 143 5.01±1.21 1.85±0.81 1.67±1.07 0.2
Prunuspersica 3 70 10.92±2.27 2,23±0.78 3,26±1.27 <0.05
Quercusafares 2 114 6,15±1.19 2,24±0.49 2.28±0.48 3.6
Quercuscoccifera 3 163 6.49±1.58 1.87±0.63 2.56±1.10 3.7
Quercussuber 3 121 6,41±1.15 1.03±0.22 0,92±0.22 1.4
Rosmarinusofficinalis 3 215 14.77±5.88 11.35±3.56 16.20±7.5 0.1
Spartiumjunceum 3 135 7.53±1.45 2,15±0.32 2.77±1.16 1.1
of 16 Mediterranean species. Furthermore, the monoter- 3.4 Plantphysiology
pene species composition emitted from the investigated
tropical plants was quite conservative, in contrast to the
ThenetexchangeofCO wasmonitoredalongallmeasure-
greatvariationofthepatternobservedamongMediterranean 2
ments to note the physiological activities of the enclosed
plants.Sesquiterpenesweredetectedonlyinemissionsfrom
plants. The data confirmed that all plants investigated were
Mediterranean vegetation. However, although our experi-
photosyntheticallyactive(Table7).Netphotosyntheticrates
mentsdidnotdetectanysesquiterpeneemissionsfromtrop-
(NPR) were found in the range of 1.8–8.2µmolm−2s−1
ical vegetation, their existence in Amazonian forest air has
and3.3–23µmolm−2s−1forAmazonianandMediterranean
beenrecentlydemonstrated(Jardineetal.,2011).Emissions
plants,respectively.Suchrateshavebeenreportedforshade
of methanol were found to be widely distributed in plants
leavesoftropicalC3-plants(DaMattaetal.,2001;Larcher,
of both ecosystems. This can be understood as a conse-
2003)andforMediterraneanplantsinspringorautumn(Llu-
quenceofgrowth(Fall,2003).Inaddition,acetoneemissions
siaandPen˜uelas,2000).Mostly,thetranspirationrateswere
were found only in one tropical plant species, whereas five
<6mmolm−2s−1exceptforCistusmonspeliensis,Rosmar-
of the investigated Mediterranean species emitted this VOC
inusofficinalis,Heveaspruceana(igapo´)andPouteriaglom-
species.
erata, showing higher values (Table 7) and consequently
Biogeosciences,10,5855–5873,2013 www.biogeosciences.net/10/5855/2013/