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Vertical profile of concentration and flow of aerosol particles over arable land
Zapletal, Miloš ; Hovorka, J. ; Hladík, J. ; Juráň, Stanislav
At present, the immission load of the territory and population by solid / liquid or mixed particles with the size of 1 nm - 100 μm suspended in the atmosphere, or PM, is one of the biggest problems not only in the Czech Republic but practically throughout Europe. High PM concentrations are associated with a large number of health problems. These include respiratory disorders and an increased risk of lung and skin cancer (WHO, 2006). In the Czech Republic, long-term exposure to PM is an important factor responsible for reducing the quality of life of the population. Among the most serious effects in terms of overall health burden is a significant reduction in life expectancy (WHO, 2006). Transport and industrial activities are generally considered to be the main source of PM10 particles. Existing information on the chemical composition, size distribution, secondary particle fraction and deposition flux of particles on different types of surfaces is still incomplete. Aerosol concentration measurements have been performed in many cities at street level or for personal exposure assessment (Kaur et al., 2005, Longley et al., 2004). Eddy covariance measurements of particulate emission flux over large urban agglomerations were performed (Dorsey et al., 2002, Järvi et al., 2009, Martin et al., 2009, Deventer et al., 2013). Direct measurement of the emission flux of the eddy particles by the covariation method provided information on the upward air flow and vertical particle exchange over some urban agglomerations (eg Manchester, London, Helsinki). A description of the measurement of the eddy particle flow by the covariance method from an aircraft is given in Buzorius et al. (2006). Less information exists on the emission flux of particles above different types of sources at different heights, eg above arable land, opencast coal mine or local fireplaces.
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Measured and modelled fluxes of tropospheric ozone in mountainous Norway spruce forest
Juráň, Stanislav ; Zapletal, Miloš ; Večeřa, Zbyněk ; Cudlín, Pavel ; Urban, Otmar
Tropospheric ozone fluxes (O3) were measured in Norway spruce forest at Bily Kriz, Czech Republic by eddy covariance technique. Within-canopy concentration gradient was measured by APOA-370 analysers (Horiba, Japan) in 7m, 25m and 30m above ground. Fluxes of O3 were modelled from the concentration gradient by applying Inverse Lagrangian Transport Model (Raupach, 1989). Next, O3 fluxes were modelled on the basis of resistent analogy. Ozone flux measured by eddy covariance technique amounted up to 1.19 nmol m-2 s-1 on daily average and the lowest -0.75 nmol m-2 s-1. Studied forest stand was net sink for ozone in 7.14 mmol m-2 per day (=0.343 g m-2 per day). The highest ozone emission peaked during noon hours, suggesting closure of stomata due to low air temperature and ozone production due to sufficient radiation. Both models proved to be imprecise when compared to measured data in autumn-winter transition period.
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Modulation of ozone flux in a mountain spruce forest under different cloud cover
Juráň, Stanislav ; Fares, S. ; Urban, Otmar
Ozone (O3) fluxes were modelled from a concentration gradient in a Norway spruce forest at the Bílý Kříž experimental station for years 2012–2016. Daily and seasonal O3 depositions were calculated separately for days with cloudy, partly cloudy, and clear sky conditions. The hypothesis that overcast conditions modulate O3 flux in the forest ecosystem via controlled stomatal conductance is tested. Indeed, the highest stomatal conductance followed by the highest O3 deposition was found during partly cloudy and cloudy sky conditions in all seasons.
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Diurnal changes of monoterpene fluxes in Norway spruce forest
Juráň, Stanislav ; Fares, S. ; Křůmal, Kamil ; Večeřa, Zbyněk ; Urban, Otmar
Biogenic volatile organic compounds (BVOCs) are important components of biosphere–atmosphere exchange. Their emissions depend on various meteorological parameters and stresses. Diurnal fluxes of different monoterpenes were studied within a Norway spruce (Picea abies) mountain forest to investigate their dependence on temperature and global radiation. Fluxes of monoterpenes, the most abundant BVOCs in spruce, were modelled using an inverse Lagrangian transport model, and representative diurnal variation trigged by both temperature and light was observed. This research enables future parametrization and quantification of various factors driving bidirectional fluxes.
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