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| Titel |
Shoot-level monitoring of O3 and NOx fluxes of Scots pine (Pinus sylvestris L.) |
| VerfasserIn |
Johanna Joensuu, Nuria Altimir, Maarit Raivonen, Pasi Kolari, Petri Keronen, Timo Vesala, Jaana Bäck, Pertti Hari, Eero Nikinmaa |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053773
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| Zusammenfassung |
| O3 and nitrogen oxides (NOx=NO+NO2) are important atmospheric pollutants. Both are
involved in atmospheric chemistry in various significant ways. O3 is a greenhouse gas.
Both gases have potentially harmful effects on plants, but NOx can have nutritional
as well as toxic effects. One of the processes underlying the atmospheric balance
of O3 and NOx is their interaction with vegetation. Both are removed, absorbed,
and NOrmx potentially also emitted by the foliage. The mechanisms driving these
processes are not known in sufficient detail for accurate modeling of leaf-level
O3 and NOx fluxes for the needs of i.e. global atmosphere-biosphere models. For
example, the role of biogenic volatile compounds (BVOCs) in ozone scavenging and
the role of nitrate in the biological and chemical NOx emissions require further
research.
The SMEAR II (Station of Measuring Forest Ecosystem-Atmosphere Relations) station in
Hyytiälä, Finland, is well-known for its series of shoot-level O3 and NOx fluxes measured on
Scots pine (Pinus sylvestris L.) in the field. Measurements from shoot-scale gas exchange
chambers have provided valuable insights into O3 and NOx exchange (i.e. Raivonen & al.
2009, Altimir & al. 2006). The measuring system has since been upgraded with at least two
major improvements:
- A new chamber type was designed in order to remove the enclosure effect. The chamber
is built as a sliding box that encloses the shoot only for the short time needed to make a
measurement and otherwise allows the shoot to experience all occurring ambient conditions,
including wind and rain.
-In order to allow targeted flux measurement of NOx, not NOy, the molybdenum
converter of the NOx analyser was replaced with a photolytic, NO2-specific one.
We present preliminary results of O3 and NOx shoot-scale flux measurements after these
improvements and discuss their value in increasing our understanding of the shoot-scale
processes involving O3 ad NOx.
Altimir N., Kolari P., Tuovinen J.-P., Vesala T., Bäck J., Suni T., Kulmala M. & Hari P.
2006. Foliage surface ozone deposition: a role for surface moisture? Biogeosciences 3 :
209-228.
Raivonen M., Vesala T., Pirjola L., Altimir N., Keronen P., Kulmala M. & Hari P. 2009.
Compensation point of NOx exchange: Net result of NOx consumption and production. Agric
for Meteorol 149(6-7):1073-81. |
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