MEASUREMENTS OF ATMOSPHERIC PARTICULATE CARBON IN LITHUANIA

During 1985 - 1989 particulate carbon concentrations were determined a t suburban and rural sites in Lithuania. The main part of the continuo us measurements was conducted at Preila background station (Curonian s pit). Daily samples of airborne particulate matter were collected on g lass fiber filters or by impactors and analysed for total carbon (TC), benzene extractable organic carbon (BEOC) and elemental carbon (EC) u sing combustion and optical techniques. Monthly median concentrations of total particulate carbon varied in the range 2 - 22 mu g/m(3) durin g the period of measurements. For all the forms of particulate carbon the strong seasonal dependence was observed. The very regular seasonal cycle is characteristic for the ratio EC/TC: 0.10 - 0.15 and 0.30 - 0 .35 for warm and cold periods respectively. Size distribution measurem ents shows that the main part of TC is in the sub-micron particle frac tion - about 80 - 90% in summer and even 92 - 98% in winter. The conce ntrations of TC in size fraction <1.2 mu m have sharp winter peaks and summer minima. Very low concentrations and summer maxima for TC in th e fraction >3.5 mu m have been observed. The concentrations of EC in p recipitation varied from 0.02 to 0.7 mg/l and average wet deposition f lux of EC was 5 - 7 and maximum 15 - 20 mg/m(2) per month.