Field investigations of nitrogen dioxide (NO 2) exchange between plants and the atmosphere

Breuninger, C.; Meixner, F. X.; Kesselmeier, J.

The nitrogen dioxide (NO 2) exchange between the atmosphere and needles of Picea abies L. (Norway Spruce) was studied under uncontrolled field conditions using a dynamic chamber system. This system allows measurements of the flux density of the reactive NO-NO 2-O 3 triad and additionally of the non-reactive trace gases CO 2 and H 2O. For the NO 2 detection a highly NO 2 specific blue light converter was used, which was coupled to chemiluminescence detection of the photolysis product NO. This NO 2 converter excludes known interferences with other nitrogen compounds, which occur by using more unspecific NO 2 converters. Photo-chemical reactions of NO, NO 2, and O 3 inside the dynamic chamber were considered for the determination of NO 2 flux densities, NO 2 deposition velocities, as well as NO 2 compensation point concentrations. The calculations are based on a bi-variate weighted linear regression analysis (y- and x-errors considered). The NO 2 deposition velocities for spruce, based on projected needle area, ranged between 0.07 and 0.42 mm s −1. The calculated NO 2 compensation point concentrations ranged from 2.4 ± 9.63 to 29.0 ± 16.30 nmol m −3 (0.05–0.65 ppb) but the compensation point concentrations were all not significant in terms of compensation point concentration is unequal to zero. These data challenge the existence of a NO 2 compensation point concentration for spruce. Our study resulted in lower values of NO 2 gas exchange flux densities, NO 2 deposition velocities and NO 2 compensation point concentrations in comparison to most previous studies. It is essential to use a more specific NO 2 analyzer than used in previous studies and to consider photo-chemical reactions between NO, NO 2, and O 3 inside the chamber.

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Breuninger, C. / Meixner, F. X. / Kesselmeier, J.: Field investigations of nitrogen dioxide (NO2) exchange between plants and the atmosphere. 2013. Copernicus Publications.

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