Dry deposition velocity, for

At present evaluation of POP depositions to various types of the underlying surface are under investigations. The spatial distribution of PCB-153 depositions to areas covered with forests, soil and seawater in 2000 is demonstrated in Figure 13. Depositions of this pollutant to forests, soil and seawater were estimated using different parameterizations of dry deposition velocities for different types of underlying surfaces. This resulted in considerable differences in depositions to the considered areas. As seen from the maps, the highest levels of PCB-153 depositions were characteristic of forested areas (Dutchak et al., 2004). 

HCHO (0.33 cm s-1) (Brasseur et al., 1998) and it has been assumed that the dry deposition velocity for CH3CHO and other aldehydes is the same as that for HCHO. 

Equation 10 is used to calculate the dry deposition velocity for NO2. It is assumed that all of the N02 in the dew came from the dissolution of NO2. A value of 0.03 cm/s is found for the deposition velocity. To calculate the dry deposition velocity for HNO3, it is assumed that the source of dew N03 was the dry deposition of HNO3. The calculated value, 2.0 cm/s, appears high relative to the velocities of other soluble gases such as HCHO (see Tables II and IV) and likely reflects that HNO3 can be adsorbed onto a dry surface. Evidence to substantiate this point appears in the next section. It is also possible that some of the NO3 and/or NO2 arose from the deposition of small amounts of PAN however, the ionic fate of dissolved PAN is not known and therefore more information is required for an assessment of its role in atmospheric corrosion. 

Dry deposition velocities for gases to a variety of surfaces are available in the literature (see, for example, Dolske and Gatz, 1985 Colbeck and... 

Fig. 7-29. Dry deposition velocities for particles as a function of size according to field and laboratory measurements of Chamberlain (1953, 1966a), Mollerand Schumann (1970), Sehmel and Sutter (1974), Clough (1975), Little and Wiffen (1977), and Wesley et al. (1977). Filled symbols are for deposition onto grass and open symbols are for deposition onto water surface. The solid line indicates the sedimentation velocity. Wind speed A, u = 2 m/s O, u = 8 m/s O, u = 14 m/s.

Fig. 10-9. Flux diagram for sulfur in the unperturbed marine atmosphere. Fluxes are given in units of p.gS/m2day. Numbers in boxes indicate column densities in units of p.gS/m2. DMS, Dimethyl sulfide MSA, methane sulfonic acid (associated with the aerosol). The mixing ratio of S02 is 60 ng S/m3, independent of altitude. The mixing ratio of SOis 280 ng S/m3 in the boundary layer and 80 ng S/m3 in the free troposphere. Contrary to the model of Kritz (1982), the fluxes are confined to the boundary layer. There exists no significant net flux into or out of the free troposphere. The dry deposition velocity for S02 is 5mm/s.

TABLE 19.1 Typical Dry Deposition Velocities for Some Atmospheric Gases... 

Recapitulating, the dry deposition velocity for vapor species i is related to the three resistances by... 

Table 4.19 Averaged dry deposition velocities for SO2 (in cm s ) after Moller (2003).

THE ATMOSPHERE TABLE 4.8 Dry Deposition Velocities for Several Gases ... 

Brook, J.R., Sirois, A., Clarke, J.F., 19%. Comparison of dry deposition velocities for SO2, HNO3 and S04 estimated with two inferential models. Water Air Soil Pollut. 87,205-218. Brook, J.R., Di-Giovanni, F., Cakmak, S., Meyers, T.P., 1997. Estimation of dry deposition velocity using inferential models and site-specific meterology-uncertainty due to siting... 

S A1 Dry deposition velocity for gases and chemical vapors from air-to-the soil and ground surfaces SA2 Dry deposition velocity for particles and associated sorbed chemicals from air to earthen surfaces SA3 Wet deposition velocity for gases and chemical vapors from air to earthen surfaces S A4 Wet deposition velocity for particles and associated sorbed chemicals from air to earthen surfaces SA5 Air-side MTC for gases and vapor from soil and ground surfaces into the lower atmospheric boundary layer... 

S A8 Dry deposition velocities for particles and associated chemicals from air to the plant canopy surfaces... 

Calculated Dry Deposition Velocities for a Smooth, Flat Surface Based on Size Distribution Data in the Literature for Pb, Mn, and Ca... 

Yang, H.H., L.T. Hsieh, and S.K. Cheng, Determination of atmospheric nitrate particulate size distribution and dry deposition velocity for three distinct areas. Chemosphere, 2005. 60(10) 1447-1453. 

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