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The accumulation and desorption of gaseous DDE in spruce needles was investigated in two chamber experiments using Picea omorika and in a third using Picea abies. The P. omorika needles were divided into two fractions for analysis: the soluble cuticular lipids and the remaining needle. The data were used to parameterize a one-compartment (complete needle) and a two-compartment (surface, reservoir) plant model. The one-compartment model performed poorly, whereas the uptake and clearance behavior of the complete needle was described very well with the two-compartment model. However, the two model compartments did not correspond to the two needle fractions that were analyzed for P. omorika. The validation of the P. abies model using environmental data was quite successful, whereas the validation of the P. omorika model gave poor results. It was concluded that chamber experiments are not sufficient for describing the air/plant exchange of contaminants for which the halflife of the exchange process with the slowest leaf compartment is longer than the length of the experiment. Furthermore, model validation is essential if the results of chamber experiments are to be extrapolated to environmental conditions.

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The overall objective of this work is to provide the first evaluation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) occurrence and deposition to Mediterranean open seawater. sigma2,3,7,8-PCDD/F air (gas+aerosol) concentrations over the Mediterranean Sea ranged from 60 to 1040 fg m(-3). The highest value (1555 fg m(-3)) was measured in a reference sample taken in the SW Black Sea. No consistent trend regarding the diel cycle of PCDD/Fs was observed. PCDD/Fs transported to the open sea waters from continental areas and across the Atlantic as well as ship emissions may be significant sources to the open Mediterranean. Seawater concentrations in the Mediterranean ranged from 42 to 64 fg L(-1). The sigma2,3,7,8-PCDD/F dry deposition fluxes in the Marmara and Black Seas (210 kg year(-1)) are from 2 to 55 times higher than dry fluxes in the Mediterranean Sea (4-156 kg year(-1)). Analysis of estimated diffusive air-water fluxes and air/water fugacity ratios show that a net volatilization of some PCDD congeners is feasible. However, evidence of a net absorption flux for the rest of PCDD/F is found. When both atmospheric deposition processes are considered together the open Mediterranean Sea is a net sink of PCDD/F, due to the importance of dry deposition fluxes of aerosol-bound PCDDFs.