210Pb as a tracer of the deposition of sub-micrometer aerosols

210Pb deposition rates can be obtained in soils in which the organic matter is concentrated in a surface layer. If the organic matter is uniformly distributed through the soil, the correction for 210Pb produced becomes larger and the precision of the deposition rate estimate decreases. Forest soils are generally well suited for 210Pb deposition rate measurements. The rate of 210Pb deposition to New England lowlands averages 1.0 dpm cm-2 yr-1. There is no evidence for systematic spatial variability in the deposition rate. Deposition rates are uniform. The amount of dry deposition of 210Pb is too small to be measured by the methods used. Even in an area where impaction on foliage is a major removal mechanism for giant aerosols, vegetation has no apparent effect on the 210Pb deposition rate. The 210Pb deposition rate in a mountainous region is determined by the rate of water deposition by precipitation and in-cloud droplet impaction. The deposition rate of other species originating from the continental surface and residing in sub-micrometer aerosols, such as sulfate, should be estimatable at any given site using the species/210Pb deposition ratio in aerosol particles and the 210Pb deposition rate at that site. 24 references, 1 figure, 1 table