Water transport atmosphere

This explanation for the surface salinity differences between the Atlantic and Pacific does not provide the whole story because it overlooks the need to budget atmospheric water transport on a global basis. In fact, the only way to cause a net salinity change in an ocean due to evaporation is via net transport of water vapor to another region on a time scale that is short with respect to the residence time (decades to centuries) of the surface water in question. Simply removing water from an ocean to the atmosphere or to an adjacent landmass is insufficient if that same water rapidly returns to the source ocean. To create a salinity difference between oceans. 

The major function of cutin is to serve as the structural component of the outer barrier of plants. As the major component of the cuticle it plays a major role in the interaction of the plant with its environment. Development of the cuticle is thought to be responsible for the ability of plants to move onto land where the cuticle limits diffusion of moisture and thus prevents desiccation [141]. The plant cuticle controls the exchange of matter between leaf and atmosphere. The transport properties of the cuticle strongly influences the loss of water and solutes from the leaf interior as well as uptake of nonvolatile chemicals from the atmosphere to the leaf surface. In the absence of stomata the cuticle controls gas exchange. The cuticle as a transport-limiting barrier is important in its physiological and ecological functions. The diffusion across plant cuticle follows basic laws of passive diffusion across lipophylic membranes [142]. Isolated cuticular membranes have been used to study this permeability and the results obtained appear to be valid... 

The distribution of Hg within seepage lakes is a net result of the processes that control Hg transport between the atmosphere, water column, seston, sediments, and groundwater. This discussion focuses on the processes that control the exchange of Hg between the sediments and lake water. We first present data on spatial and temporal concentrations in the water column, sediments, pore water, and groundwater. These data set the context for a subsequent discussion of the chemical and physical processes responsible for the transport of mercury across the sediment-water interface and are necessary for assessing transport rates. 

The processes of transport at the atmosphere-water surface border have been well studied. The transport of moisture from the surface of a water body into the atmosphere is one of the complicated physical processes of mass and energy exchange across the water-air interface (Figure 4.12). These processes are functions of many climatic parameters and, to a large extent, are regulated by eddy motions in the surface layer of the atmosphere determined by the wind field. 

The possibility of estimating water transport from the water surface into the atmosphere consists in assessing the water content of the lower part of the surface layer of the atmosphere, which forms spray and water vapor. The eddy flux of water... 

Figure 4.15. Block diagram for formation and transport of methane in waterlogged country. Notation FlCHi is the methane flux across the atmosphere/water body interface F2CHi is the oxidation of methane in aerobic zones FCH is the intensity of the methane source M is methane concentration.

Since chromium compounds cannot volatilize from water, transport of chromium from water to the atmosphere is not likely, except by transport in windblown sea sprays. Most of the chromium released... 

Besides its low natural concentrations, Hg is mostly anthropogenically introduced into the environment. The anthropogenic sources of Hg are numerous and worldwide. The annual emissions are estimated to be between 2700 and 6000 tons. The global cycle of Hg involves the emission of the metal from land and water surfaces into the atmosphere, its transport in the atmosphere on a global scale, possible conversion to unidentified soluble species, and return to land and water by various depositional processes [4]. In the aquatic system numerous transformations take place, which are mainly microbiological processes. An overview of the most common Hg species in the environment is given in Figure 22.1. 

The availability of worldwide gridded reanalysis (NCEP, ECMWF, NASA-DAO) has allowed assessments of the water vapor transport into Amazonia, and in fact some recent works have shown contradictory results in terms of trends in input moisture into the Amazon basin. For instance, Costa and Foley (1999) identified a statistically significant decreasing trend in the atmospheric transport of water both into and out of the Amazon basin, based on 20 years (1976-96) of the NCEP reanalysis. On the other hand, Curtis and Hastenrath (1999) have identified statistically significant upward trends of lower tropospheric convergence, upward flow, convergence of atmospheric water vapor transport, and precipitable water over the Amazon basin, based on the analysis of 40 years (1958-97) of the NCEP reanalysis. 

Hoyer M., Burke J., and Keeler G. (1995) Atmospheric sources, transport and deposition of mercury in Michigan two years of event precipitation. Water Air Soil Pollut. 80, 192-208. 

---