PARTICLE DEPOSITION TO FORESTS - SUMMARY OF RESULTS AND APPLICATION

Particle deposition to forest was studied at Speulder forest using exp erimental and modelling results. In this paper a short overview of the main results is given and they are applied in generalisation of depos ition in The Netherlands. The results of the Aerosol project show that the deposition of particles to forests has been underestimated until now. Particle deposition makes a reasonable contribution to the total deposition of acidifying components and base cations to forests. Param etrisations of the deposition processes were derived from the experime nts and model developed for particle deposition to Speulder forest. Th e parametrisations were used together with concentrations, meteorologi cal observations and land-use data to determine the deposition an a 5 x 5 km basis in The Netherlands. Results of the canopy exchange experi ments at Speulder forest and of the comparison of atmospheric depositi on estimates and throughfall estimates at Speuld and other locations i n The Netherlands show that throughfall fluxes and atmospheric deposit ion estimates are reasonably in agreement for all components, except n itrate. There is still large uncertainty in canopy exchange processes of oxidised nitrogen and in deposition estimates of the different gase s contributing to the total oxidised nitrogen flux. The contribution o f aerosol deposition to the total deposition in The Netherlands is 7% for SO42-, 11% for NH4+ and 9% for NO3-; for deciduous forests these n umbers are 14, 15 and 17%, and for coniferous forests 10, 17 and 20%, respectively. Dry deposition is estimated to amount to about 21% of to tal deposition for Na+, 20% for K+, 27% for Mg2+ + and 25% for Ca2+. C opyright (C) 1996 Elsevier Science Ltd