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Comparison of chemical composition of throughfall and deposited precipitation
Chaloupecký, Pavel ; Špičková, Jitka ; Fišák, Jaroslav ; Skřivan, Petr
Since June 2004 throughfall samples in beech and spruce vegetation have been taken at the observatory Milesovka. Ever since 1998 fog water samples have been taken there as well. In this paper are compared the concentrations of main ions and trace elements in throughfall and in deposited precipitation. The concentrations of main ions and trace elements in throughfal are primarily affected by the volume of samples. The highest concentrations of monitored sustances in throughfall were recorded in September and in October when the lowest rainfall totals were measured. The concentrations of monitored sustances were in throughfall mostly higher in spruce vegetation in comparison with beech vegetation. It is probably due to the thicker treetop in spruce vegetation on Milesovka observatory. Due to the thicker treetop a smaller volume of throughfall is let fall and the substances from ambient air are captured more effectively in comparison with beech vegetation. In the case of main ions the lowest concentrations were measured in fog water samples. For trace elements wasn´t data. From comparison with reference locality Lesni potok is obvious that concentrations of monitored sustances in throughfall on Milesovka exceed sharply concentrations in locality Lesni potok. This difference is considerably higher by spruce vegetation in comparison to beech vegetation which indicate that it is necessary take not only local air quality into account but also type of vegetation and thick of treetop which can very significantly contribute to the chemical composition of throughfall.
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Atmospheric deposition in the vicinity of the limestone-quarry Čertovy schody
Špičková, Jitka ; Dobešová, Irena ; Vach, Marek ; Burian, Miloš ; Skřivan, Petr
Atmospheric precipitation samples were collected in the Bohemian Karst, (30 km SW from Prague, Czech Republic) at six localities in the vicinity of the limestone-quarry Čertovy schody during years 1996-2003. Samples were analyzed for major components (Na+, K+, Mg2+, Ca2+, F-, Cl-, NO3-, HCO3-, SO42-) and trace metals (Cu, Mn, Fe, Zn, Pb, Be, As, Sr, Cd, Al, Cr). Deposition fluxes were calculated from more than 10 000 elemental analyses of samples collected monthly. The fluxes of monitored substances show temporal and spatial variability. The most marked attribute is the strong affection by local emission sources confirmed by the investigation of seasonal variability, temporal trend and correlation analysis.
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Impact of metabolites of the forest vegetation on the chemistry of throughfall
Skřivan, Petr ; Navrátil, Tomáš ; Vach, Marek ; Špičková, Jitka ; Fottová, D.
The chemistry of throughfall is a result of numerous processes that affect the concentrations of its individual components in the original wet precipitation above the tree crowns. The precipitation entering the tree crowns is generally enriched throughout its interactions with the above - ground part of the vegetation. The samples of open place precipitation and throughfall have been collected since 1989 in the region of Kostelec n. Č.lesy. The monitored area is situated predominantly in the Nature State Reserve Voděradské bučiny on the bedrock of the Říčany and Jevany granites. The exact evaluation of the impact of metabolites on the resultant concentration and fluxes of individual monitored elements in throughfall, based on mere comparison with the corresponding values in open place precipitation, is faced with several problems. First, the chemistry of throughfall reflects more the chemical composition of aerosol from lower parts of the atmosphere, as it is more or less effectively swept out by the above ground growth. The vegetation surface also entraps the reactive atmospheric gasses. Finally, the original precipitation solution is thickened through the evapotranspiration and it is enriched by the excluded and leached metabolites. The estimate of the extent of metabolic activity of the forest trees on the chemistry of throughfall was therefore limited on the comparison of a relative magnitude of normalised fluxes of individual elements in a given type of throughfall. The fluxes of individual elements in a beech- and spruce throughfall were normalised on the Na fluxes, with respect to the supposed zero metabolic share of Na in throughfall and to its predominantly natural sources in the atmospheric aerosol. The calculation of the enrichment factor Ef of the individual elements was then executed by means of the relation EfTFB,TFS (Me) = FBP Na / FTFB,TFS Na* FTFB,TFS Me / FBP Me, where EfTFB,TFS (Me) is the enrichment factor od the particular element in a given type of throughfall, FBP Na a FBP Me are the mean annual deposition fluxes of Na and the element Me on an open place, and FTFB,TFS Na a FTFB,TFS Me are the mean annual fluxes of Na and the element Me in throughfall. Values of the enrichment factor for the individual elements are presented in the article in the Tab. 1. Values higher than 1 should generally indicate the presence of metabolic products of the vegetation. The highest Ef values were found, after expectations, for the basic nutrients and significant essential elements, in a row of K > Mg > Mn > Ca. Together with these elements, significant impact of leached metabolites was also found for Rb, Sr and Ba. The enrichment of throughfall with rubidium is extraordinary high, probably even higher than that of its homologue potassium. Surprisngly high values of the Rb deposition fluxes in both tyes of throughfall certify the extensive input of this element through the root uptake of the forest vegetation, which is contingent on very close chemical characteristics of rubidium and potassium (ionic radii, electronegativity, ionic character of bonding of these alkaline metals in all their chemical compounds etc.). We have not found, however, similar pronounced paralell between Ca, Sr and especially Ba, which is even more abundant in the underlying rocks and soils than Sr.
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