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Critical survey of measurements of foliar deposition of airborne sulfates and nitrates

Conference ·
OSTI ID:6757311
This paper reviews the available data on processes affecting foliar deposition and retention of particles from the point of view of determining the effects of sulfates and nitrates on plants. The particle characteristics of size, shape, frequency distribution, and chemical speciation from typical air monitoring data are discussed in terms of dry deposition velocity and foliar collection and retention; first principles as well as empirical results are examined as methods of calculating dry deposition. Wet deposition of sulfates is examined in terms of foliar collection, foliar retention, scavenging, and the dependency upon precipitation characteristics. It is shown that the particle collection efficiency and the interception coefficient can vary over an order of magnitude due to either the effects of plant type or the misrepresentation of the roughness, Z/sub 0/, of the vegetation canopy. Particle diameter has little effect on collection efficiency in the submicron-size range but great effect at larger diameters. In wet deposition, the scavenging efficiency is very low for particles less than 4 mu m in diameter, and the scavenging coefficient is so highly dependent upon rainfall rate that it is practically case-specific. More experimental data and improvements are needed before the sulfate and nitrate effects can be accurately assessed.
Research Organization:
California Univ., Livermore (USA). Lawrence Livermore Lab.
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
6757311
Report Number(s):
UCRL-80883; CONF-780636-2
Country of Publication:
United States
Language:
English