Critique of Methods to Measure Dry Deposition; Concise Summary of Workshop

摘要

At the Workshop on Dry Deposition Methodology, held December 4 and 5, 1979, at the Argonne National Laboratory in Argonne, Illinois, dry deposition measurement techniques were assessed for routine monitoring use. A majority opinion was reached that commonly-used techniques such as surrogate surfaces and collection vessels are not sufficiently accurate for use in networks, because the highly varied properties of the natural surfaces of interest cannot be simulated adequately. Further research was recommended on dry deposition parameters in order to estimate dry deposition rates, if possible, from measurements of atmospheric concentrations at a single height, together with observations of surface properties and micrometeorological parameters. The ability to perform such investigations in the field is critically dependent upon advances in chemical and physical capabilities to provide methods with standard relative errors of less than 1 percent for a single instrument on successive measurements, or with time responses of less than 1 second. These requirements are not being achieved for many pollutant species. At present, the most promising methods for monitoring are eddy accumulation, modified Bowen ratio, and variance. Regardless of the method employed, monitoring sites should be chosen that are representative of the surrounding areas in terms of surface properties, meteorological conditions, and pollutant characteristics.