Diy deposition

Considerable work has been done on the behavior of pollutant species at air-water and air-soil interfaces. For example, wet and diy deposition measurements of various gaseous and particulate species have been made over a wide range of atmospheric and land-cover conditions. Still, the problem is of such complexity that species-dependent and particle-size-dependent rates of transfer from the atmosphere to water and soil surfaces are not completely understood. There is much to be learned about pollutant transfer at water-soil interfaces. Concern about groundwater contamination by mineral... 

Frescholtz 2002). Although ongoing and new planned field and laboratory studies are designed to further test this hypothesis, we feel that it is warranted at this time to develop a pilot-scale network of aimual ecosystem fluxes of THg in TF and LF as indicators of total atmospheric deposition. These fluxes can then be compared with measured wet plus modeled diy deposition based on both inferential and regional-scale models to develop independent estimates of total atmospheric deposition for forested catchments. We also believe that this approach could eventually be applied to a national network, such as the MDN. Although this method is best aimed at forested sites, ongoing research will address methods appropriate for other ecosystems. 

This is a very broad conclusion, and additional measurements must be made. Some of this effort (which is current) should address the problem of other pollutants and condensation nuclei that accompany the nonurban oxidant. Interpretation of these measurements will increase the specificity of separating anthropogenic sources from natural background sources. Theoretical assessments of the existing observations will shed light on the relative roles played by stratospheric injection, plant emission, background methane, and diy deposition on surfaces in the natural portion of the tropospheric ozone cycle. 

Gao, W., and M. L. Wesely, Modeling Gaseous Diy Deposition over Regional Scales with Satellite Observations. I. Model Development, Atmos. Environ., 29, 727-737 (1995). 

Quinn, T. L., and J. M. Ondov, Influence of Temporal Changes in Relative Humidity on Diy Deposition Velocities and Fluxes of Aerosol Particles Bearing Trace Elements, Atmos. Environ., 32, 3467-3479 (1998). 

Wesely, M. L., and B. B. Hicks, Recent Progress in Diy Deposition Studies, Atmos. Environ, (f999). (In press.)... 

In this chapter we will deal with some important reactions at the gas-water interface and discuss above all the partitioning of molecules between the gas phase and the water phase (Henry s law). We will also explain the processes that influence wet and diy deposition and the composition of atmospheric water droplets (clouds, fog, rain, snow, dew) and illustrate how pollutants relee.sed into the atmosphere are transferred back to the land. Attention will be paid to the disturbance of the proton balance by the oxides of C, N, and S, antliro-pogenically released into the atmosphere, and how this disturbance is transferred from the atmosphere to the terrestrial and aquatic ecosystems. 

Zobrist, J., Wersin, P., Jaques, C., Sigg, L., and Stumm, W. (1993) Diy Deposition Measurements Using Water as a Receptor, Water, Air and Soil Pollution 71, 111-130. 

Ultrajine Range (dp <0.1 fim) 366 Residence Time and Diy Deposition 366 Aerosol Dynamics in Power Plant Plumes 368 Chemical Composition of Urban Aerosols 370 /mmduction 370... 

Caibon monoKide, 85-86 atmospheric effects, 42 atmospheric chemistiy, 239-244 atmospheric concenti ations, diy deposition velocity, 969 global budget, 85-86 lifetimes, 1099 reactivity, 312... 

Atmospheric chemical constituents can precipitate by dry, wet and occult deposition. Wet and occult deposition refers to precipitation of rainwater and cloud/fog water, respectively. They are related to acid rain and acid wet deposition as sulphur oxides are transformed to sulphur acid by interaction with water in polluted atmospheres. The two processes can have a different effect, but both result in the fonnation of soluble sulphates and mostly gypsum. Although no doubt exist about acid rain damage on most building materials, the rain can also wash away accumulated pollutants. Thus, occult deposition can be more damaging, as provide moisture to activate the chemical attack of diy deposited gases and particles. Various studies have considered that wet deposition is not important compared to dry deposition [26]. 

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