Mass Balance between Emission and Deposition of Airborne Contaminants

Quantification of (1) the total mass of airborne pollutants deposited around pollution emitters, (2) the contaminated radius around these point sources, and (3) the proportion of emissions available for long-range transport remains chal lenging for environmental scientists. Here, we present a simple method for comparing yearly airborne emission figures from any point source with observed deposition estimates from the surrounding area. First, the deposition−distance function D(x) around the smokestack must be defined. This requires the empirical determination of total (water soluble + particulate) annual deposition at several locations away from the source and of the extent of the smokestack “shadow” zone. Secondly, the loading function L(x) is obtained by integrating D(x) around the point-source. This allows estimation of the yearly mass of a contaminant deposited within an area corresponding to that of a circle of radius x around the point source. Thus, emission, deposition, and (long-range) transport of airborne contaminants can be assessed quantitatively. Preliminary results from the Kola Peninsula, Russia, suggest that deposition of trace metals overwhelmingly occurs within 200 km from the source.