Diffusion ocean surface

At the air-water interface, water molecules are constantly evaporating and condensing in a closed container. In an open container, water molecules at the surface will desorb and diffuse into the gas phase. It is therefore important to determine the effect of a monomolecular film of amphiphiles at the interface. The measurement of the evaporation of water through monolayer films was found to be of considerable interest in the study of methods for controlling evaporation from great lakes. Many important atmospheric reactions involve interfacial interactions of gas molecules (oxygen and different pollutants) with aqueous droplets of clouds and fog as well as ocean surfaces. The presence of monolayer films would thus have an appreciable effect on such mass transfer reactions. 

Most readers who have seen the surface of the ocean during a moderate wind have noticed that breaking waves introduce lots of small air bubbles into the water (Fig. 10.9). The hydrostatic pressure only 1 m below the ocean surface is already equal to about 10% of the entire atmospheric pressure, so the pressure inside a bubble is c.110% of that at the ocean surface. Thus, there is a strong tendency for bubbles entrained in the downwelling limb of a breaking wave to lose some or all of their gas to the surrounding fluid by diffusion across the bubble surface. This causes the surface waters to be supersaturated with respect to saturation equilibrium. We define the degree of supersaturation, A %), as... 

Iron may be supplied to the euphotic zone from advective and diffusive processes within the ocean as well as by atmospheric deposition of particulate matter to the ocean surface. In coastal areas the water composition can be affected by the contribution of rivers and in polar regions the glacier effect, in terms of ice melt and erosion during the ice flow, can be important. 

Finally, we consider the situation at the ocean surface. The exchange of gases across the gas-liquid interface is often treated in terms of the thin-film model depicted in Fig. 1-16 (Danckwerts, 1970 Liss and Slater, 1974). The resistances due to turbulent transport in both media are here considered small compared with those in the laminar layers, where the transfer must occur by molecular diffusion. Accordingly, assuming steady-state conditions, the flux through the interface is given by... 

Carbon dioxide is transferred across the air-sea interface by molecular diffusion and turbulence at the ocean surface. The flux (F) of CO2 between the atmosphere and ocean is driven by the concentration difference between the reservoirs (eqn [2]). 

Knowledge of the visible reflectance of underlying land and ocean surfaces is necessary for calculating the diffuse radiation field. The reflectance and transmittance depend upon both the angles of incidence and reflection or transmission. For an angular beam of radiation with radiance within a cone of sohd angle dco around... 

This removal may also include diffusion of soluble U(VI) from seawater into the sediment via pore water. Uranium-organic matter complexes are also prevalent in the marine environment. Organically bound uranium was found to make up to 20% of the dissolved U concentration in the open ocean." ° Uranium may also be enriched in estuarine colloids and in suspended organic matter within the surface ocean. " Scott" and Maeda and Windom" have suggested the possibility that humic acids can efficiently scavenge uranium in low salinity regions of some estuaries. Finally, sedimentary organic matter can also efficiently complex or adsorb uranium and other radionuclides. 

The inadequacy of the two-box model of the ocean led to the box-diffusion model (Oeschger et al, 1975). Instead of simulating the role of the deep sea with a well-mixed reservoir in exchange with the surface layer by first-order exchange processes, the transfer into the deep sea is maintained by vertical eddy diffusion. In... 

Sea ice is represented in the model as a two-dimensional surface covered with a snowpack. Ice advection, rheology and snow cover are calculated from the sea-ice model embedded in MPIOM [Hibler (1979)]. The only source of pollutants for the ice compartment is deposition from the atmosphere. Once pollutants enter the ice compartment they can diffuse into the snow pore space air, dissolve in the interstitial liquid water or adsorb to the ice surface. Together with the sea ice the pollutants undergo advection. Sinks considered for the ice compartment are volatilisation to the atmosphere and release into the ocean with melt water. 

Similar affinity of polonium and plutonium for marine surfaces implies that studies of the more easily measured polonium might be valuable in predicting some consequences of plutonium disposal in die oceans [8-11]. Rates at which plutonium and polonium deposit out of seawater onto surfaces of giant brown algae and inert surfaces, such as glass and cellulose, suggest that both nuclides are associated in coastal seawater with colloidal sized species having diffusivities of about 3 x 10"7 cm2/s. The parallel behaviour possibly... 

Abstract This chapter discusses disposal to surface water, the most common method of concentrate management. This includes concentrate that is directly disposed of into rivers, creeks, lakes, oceans, bays, and other bodies of water. Concentrate is piped to the site of disposal, where it is discharged to the receiving body of water via an outfall structure. The environmental impacts of surface water disposal may be lessened by diluting the concentrate prior to discharge, or by dilution of the concentrate through the design of the outfall strucmre and diffusers. Pretreatment processes that lessen the impact on the environment should also be considered. 

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