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TitleImpact of increasing CO2, and air pollutants (NOx, SO2, O3) on the stable isotope ratios in tree rings
 
AuthorSiegwolf, R T W; Savard, M MORCID logo; Grams, T E E; Voelker, S L
SourceStable isotopes in tree rings; 2022 p. 675-710 Open Access logo Open Access
LinksOnline - En ligne
Image
Year2022
Alt SeriesNatural Resources Canada, Contribution Series 20200471
PublisherSpringer
Documentbook
Lang.English
Mediapaper; on-line; digital
File formatpdf
Subjectsenvironmental geology; Nature and Environment; carbon dioxide; pollution; pollutants; isotopes; stable isotope studies; Trees
Illustrationsschematic diagrams
ProgramEnvironmental Geoscience Environmental Studies and Assessments
Released2022 06 07
AbstractAnthropogenic activities such as industrialization, land use change and intensification of agriculture strongly contribute to changes in the concentrations of atmospheric trace gases. Carbon dioxide (CO2), oxidized N compounds (NOx), sulfur dioxide (SO2) and ozone (O3) have particularly significant impacts on plant physiology. CO2, the substrate for plant photosynthesis, is in the focus of interest as the ambiguous effect of its increasing concentration is controversially discussed. Is its increase beneficial for plants or are plants non-responsive? NOx, a product of combustion and lightning, can have either fertilizing or toxic effects depending on the concentration and form. This is also the case for reduced forms of nitrogen (NHy), which are mostly emitted from agricultural and industrial activities. In combination CO2 and N compounds can have a fertilizing effect. SO2 and ground-level O3 are mostly phytotoxic, depending on their concentrations, daily and seasonal exposure dynamics, and tree health condition. Elevated concentrations of both substances arise from industrial combustion processes and car emissions. All of the above-mentioned gaseous compounds affect plant metabolism in their specific ways and to different degrees. This impacts the isotope fractionation leaving specific fingerprints in the C, O, (H) and N isotope ratios of organic matter. In this chapter we will show how the impact of increasing CO2 and air pollutants are reflected in the isotopic ratios of tree rings. Increasing CO2 shows a considerable variation in responses of d13C and to a minor degree in d18O. Ozone and SO2 exposure cause an overall increase of the d13C values in tree rings and a slight decrease in d18O, mimicking an increase in net photosynthesis (AN) and to a minor degree in stomatal conductance (gs). However, directly measured AN and gs values show the opposite, which does not always correspond with the isotope derived gas exchange data. NO2 concentration as it is found near highly frequented freeways or industrial plants causes an increase of d13C while d18O decreases. This indicates an increase in both AN and gs, which corresponds well with directly measured gas exchange data. Thus the air quality situation must be taken in consideration for the interpretation of isotope values in tree rings.
Summary(Plain Language Summary, not published)
Human activities such as industrialization, land use change and agriculture strongly contribute to increase atmospheric carbon dioxide (CO2), oxidized N compounds (NOx), sulfur dioxide (SO2) and ozone (O3). All of these compounds affect plant metabolism in their specific ways and to different degrees, leaving their fingerprints in the C, O (H) and N isotope ratios of organic matter. In this chapter we show how the impact of increasing CO2 and air pollutants are reflected in the isotopic ratios of tree rings that are potential indicators for environmental changes.
GEOSCAN ID327309

 
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