Impact atmospheric flux

If this excess absorption by clouds is ultimately shown to be a real phenomenon, then an increased cloud formation and extent due to anthropogenic emissions may alter the radiative balance of the atmosphere not only through increased reflectance but also through increased absorption of solar radiation. Such an effect could impact atmospheric temperatures, their vertical distribution, and circulation, as well as surface wind speeds and the surface latent heat flux (Kiehl et al., 1995). Hence establishing if this is truly excess absorption, and if so, its origins, is a critical issue that remains to be resolved. 

Two specific case studies focused on the impact of vehicle tire wear to the Zn budget of watersheds in the Washington, DC metropolitan area. For Lake Anne, a suburban watershed located 40 km southwest of Washington, DC, the wet deposition atmospheric flux of Zn was 8p,gcm yr (Davis and Galloway, 1981) and the flux of Zn... 

Estimate the atmospheric transmissivity Estimate the received thermal flux q. Determine the thermal impact. 

The atmospheric chemistry of nitrogen is quite complex and involves literally hundreds or thousands of chemical reactions. Although the fluxes are much smaller than the biological fluxes, these processes are important for a variety of reasons, including impacts on climate, stratospheric ozone, and photochemical smog. In this section we present an overview of the most important processes. 

The overall effect of the terrestrial weathering reactions has been the addition of the major ions, DSi, and alkalinity to river water and the removal of O2, and CO2 from the atmosphere. Because the major ions are present in high concentrations in crustal rocks and are relatively soluble, they have become the most abimdant solutes in seawater. Mass-wise, the annual flux of solids from river runoff (1.55 x 10 g/y) in the pre-Anthropocene was about three times greater than that of the solutes (0.42 x 10 g/y). The aeolian dust flux (0.045 X 10 g/y) to the ocean is about 30 times less than the river solids input. Although most of the riverine solids are deposited on the continental margin, their input has a significant impact on seawater chemistry because most of these particles are clay minerals that have cations adsorbed to their surfaces. Some of these cations are desorbed... 

Esser and Turekian (1988) estimated an accretion rate of extraterrestrial particles in ocean bottom and in varved glacial lake deposit on the basis of osmium isotope systematics and concluded a maximum accretion rate of between 4.9 x 104 and 5.6 x 104 tons/a. The discrepancy between this estimate and those derived from helium can easily be attributed to the difference in the size of the cosmic dust particles under consideration. Cosmic dusts of greater than a few ten micrometers may not be important in the helium inventory of sediments because the larger grains are likely to lose helium due to atmospheric impact heating (e.g., Brownlee, 1985). Stuart et al. (1999) concluded from studies on Antarctic micrometeorites that 50- to 1 OO-qm micrometeorites may contribute about 5% of the total flux of extraterrestrial 3He to terrestrial sediments. Therefore, the helium-based estimate deals only with these smaller particles. 

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