ATMOSPHERIC FLUXES OF PERSISTENT SEMIVOLATILE ORGANIC POLLUTANTS TO AFOREST ECOLOGICAL-SYSTEM AT THE SWEDISH WEST-COAST AND ACCUMULATION IN SPRUCE NEEDLES

Measurements of polycyclic aromatic hydrocarbons (PAHs) and polychlori nated biphenyls (PCBs) have been carried out in a forested area at Lak e Gardsjon. The overall aim of this study was to identify the importan ce of atmospheric fluxes for the occurrence of persistent semivolatile organic compounds in a forest at the Swedish west coast and to measur e the major pathways of circulation and accumulation of these contamin ants within a terrestrial ecosystem. The sampling was undertaken in ca mpaigns chosen to represent different seasons. The measurements carrie d out in 1991-94 were concentrated on the uptake of persistent organic pollutants (POPs) in spruce needles in relation to concentrations in air and amounts in deposition, while the measurements undertaken in 19 95 also included sampling of throughfall, litterfall and run-off. The concentrations of PCBs and PAHs in the different compartments have bee n used to identify important reservoirs and to estimate the annual flu xes of these compounds. The results of measurements showed that atmosp heric fluxes are important for the occurrence of PCBs and PAHs in fore st at the Swedish west coast. A seasonal variation was found in the at mospheric concentrations, and the ambient temperature was important fo r PCBs in air. The amounts of PAHs and PCBs deposited to the Gardsjo a rea (open field) were similar to those obtained during measurements at coastal- and sea-based sites at the Swedish west coast. Soot episodes at the Swedish west coast affected the deposition fluxes of POPs in t he forest. There seemed to be both an accumulation and release of POPs in different compartments in this forest ecosystem. A greater deposit ion of POPs was found in the forest soil via throughfall compared with the open field deposition. An estimate of the fluxes of PAHs and PCBs in the catchment area in a forest showed that the soil is the main re servoir for POPs in this area. (C) 1998 Elsevier Science Ltd. All righ ts reserved.