Wet deposition of elemental carbon in Lithuania.

Elemental carbon (EC) was measured in monthly precipitation samples at 14 rural sites in Lithuania from December 1986 to June 1990. The amount of EC in the sample was determined by the light reflectance method after a procedure including the filtration through a 0.2-micron polyamide membrane filter, the chemical digestion of biogenic material and the dispersion of the mixture in an ultrasonic bath. Monthly elemental carbon concentrations in the precipitation samples during the measurement period at the Preila site varied from 8 to 530 micrograms l-1 with a volume-weighted mean of 100 micrograms l-1. The range of EC monthly deposition fluxes was from 0.5 to 25 mg m-2 month-1 for all the sites. The wet deposition of elemental carbon is doubled during the cold season of the year. The estimated mean value of EC washout ratio for Preila site is 97 (range 5-243). An even distribution of the elemental carbon deposition is characteristic for the rural sites in Lithuania and mean monthly deposition flux can be estimated as 6.2 mg m-2 month-1. It results in the deposition of approximately 4800 t of elemental carbon to the area of Lithuania annually.