Origins of 210Po in the atmosphere at lamto, ivory coast: Biomass burning and saharan dusts

Measurements of 210Po and 210Pb activities in surface air at Lamto (Ivory Coast) during 18 months are presented and discussed in relation to the regional sources of 210Po. High seasonal variation is observed with maximum in winter, reaching an activity of 210Po as high as I Bq per 103 m3. Our estimation shows that the high 210Po activity in winter is not closely related to the local biomass burning emissions but rather due to the particular atmospheric circulation patterns and geographical location of this region: in winter, surface winds having continental origin bring soil dusts, enriched in 210Po and 210Pb, from Sahara desert. However, biomass burning and the growth from 222Rn within the atmosphere appear to be the major sources of unsupported 210Po in the other seasons.