Vertical flux

Development in recent years of fast-response instruments able to measure rapid fluctuations of the wind velocity (V ) and of fhe tracer concentration (c ), has made it possible to calculate the turbulent flux directly from the correlation expression in Equation (41), without having to resort to uncertain assumptions about eddy diffusivities. For example, Grelle and Lindroth (1996) used this eddy-correlation technique to calculate the vertical flux of CO2 above a foresf canopy in Sweden. Since the mean vertical velocity w) has to vanish above such a flat surface, the only contribution to the vertical flux of CO2 comes from the eddy-correlation term c w ). In order to capture the contributions from all important eddies, both the anemometer and the CO2 instrument must be able to resolve fluctuations on time scales down to about 0.1 s. 

Smith, S. V., Kimmerer, W. J., and Walsh, T. W. (1986). Vertical flux and biogeochemical turnover regulate nutrient limitation of net organic production in the North Pacific Gyre. Limnol. Oceanogr. 31, 161-167. 

The vertical flux ratio of the radionuclides, Rv, is measured in the trap ... 

Adkins JF, Boyle EA, Keigwin LD, Cortijo E (1997) Variability of the North Atlantic thermohaline circulation during the last interglacial period. Nature 390 154-156 Anderson RF (1982) Concentration, vertical flux and remineralization of particulate uranium in seawater. Geochim Cosmochim Acta 46 1293-1299... 

Cramer J (1973) Model of the circulation of DDT on Earth. Atmospheric Environment 7 241-256 Cziudaj G (2005) Die Rolle der Ozeane bei der globalen Verteilung von organischen Schadstoffen PCB als Modellsubstanzen. PhD thesis, Christian Albrechts University Kiel Dachs J, Bayona JM, Fowler SW, Miquel J, Albaiges J (1996) Vertical fluxes of polycyclic aromatic hydrocarbons and organochlorine compounds in the western Alboran Sea (southwestern Mediterranean). Marine Chemistry 52 75-86... 

Lee, C., and C. Cronin. 1982. The vertical flux of particulate organic nitrogen in the sea decomposition of amino acids in the Peru upweUing area of the equatorial Atlantic. Journal of Marine Research 40 227-251. 

Because of the similarity of transport in biotilms and in stagnant sediments, information on the parameters that control the conductivity of the biofilm can be obtained from diagenetic models for contaminant diffusion in pore waters. Assuming that molecular diffusion is the dominant transport mechanism, and that instantaneous sorption equilibrium exists between dissolved and particle-bound solutes, the vertical flux ( ) through a stagnant sediment is given by (Berner, 1980)... 

Measurements of radionuclides are also used to determine removal mechanisms and controls for carbon and metal cycling in the ocean. For example, the removal of Th from the euphotic zone is closely coupled to the vertical flux of particulate organic carbon. The deficiency of Th with respect to its parent—near-surface waters is used to estimate the export flux of particulate organic carbon (Buesseler, 1991). Measurements of Th and in the upper water column provided the primary data relahng to particulate carbon fluxes during JGOFS. 

The mass balance equations for the epilimnion and hypolimnion look like Eq. 21-38, except for the air-water exchange fluxes which are replaced by the vertical fluxes across the thermocline, 7) EH and 7) HE. According to the general form of mass transfer models (Eq.18-4), we can express these fluxes as ... 

In Illustrative Example 19.2 we discussed the flux of trichloroethene (TCE) from a contaminated aquifer through the unsaturated zone into the atmosphere. The example was based on a real case of a polluted aquifer in New Jersey (Smith et al., 1996). These authors compared the diffusive fluxes, calculated from measured TCE vapor concentration gradients, with total fluxes measured with a vertical flux chamber. They found that the measured fluxes were often several orders of magnitude larger than the fluxes calculated from Fick s first law. In these situations the vapor profiles across the unsaturated zone were not always linear. The authors attributed this to the influence of advective transport through the unsaturated zone. In order to test this hypothesis you are asked to make the following checks ... 

Calculate the vertical steady-state profile of benzene as well as the total vertical flux of benzene, XFbenzene (expressed as mass per unit time), if the following conditions hold ... 

Gidel, L.T., and Shapiro, M.A. (1980) General circulation model estimates of the net vertical flux of ozone in the lower stratosphere and the implications for the tropospheric ozone budget, J. Geophys. Res. 85, 4049-... 

It is the aim of this contribution to contrast the effect of vertical fluxes of material in the open ocean with horizontal transport which is likely to be important in shallow-water systems. The models described below are based on a number of simplifying assumptions, therefore the results must be treated with caution. In particular the magnitude of predictions may not always be realistic, although the relative proportions and sequence of events modelled are believed to reflect the real situations. 

Boetius, A., T. Ferdelman, and K. Lochte. 2000. Bacterial activity in sediments of the deep Arabian Sea in relation to vertical flux. Deep-Sea Research II 47 2835—2875. 

In fully developed flow over an extensive uniform surface, there is a constant flux layer in which all entities depend only on z. Here the vertical flux of momentum is equal to the stress r at the surface giving... 

From (6.26) the dependence of the vertical flux of dust on u at the Nevada Test Site was the same as the dependence of horizontal advection on w in Bagnold s work. At the Texas site, where severe soil... 

The resuspension of radioactive fallout can be related to the activity originally deposited. If 4 (Bq m-2) is the activity on the ground, xi (Bq m-3) the airborne activity, and Q (Bq m-2 s-1) the vertical flux, the resuspension factor is defined. 

Dachs, J., Bayona, J.M., Fowler, S.W., Miquel, J.C., Albaiges, J., 1996. Vertical fluxes of polycyclic aromatic compounds and organochlorine compounds in the western Alboran Sea (south-western Mediterranean). Mar. Chem. 52, 75-86. 

In the absence of direct field measurements of pesticide fluxes eminating from a sprayed forest a series of suppositions may be drawn from similar observations of losses from treated agricultural crops. The volatilization of dieldrin and heptachlor from a grass pasture was characterized by rather marked diurnal variations in vertical flux intensities of both insecticides during the initial days post application (12). The authors concluded that the volatilization ceased or was greatly reduced with decreased solar radiance. Estimated relative vapour concentrations of dieldrin rapidly declined from saturation 2 hours post application to 10% by evening. This parameter reached a maximum of 30 - 40% on day 2 and 20 - 25% on day 3. Although the saturated vapour concentration of heptachlor is approximately fifty... 

Michaels, A.F., Caron, D.A., Swanberg, N.R., Howse, F.A., and Michaels, C.M., Planktonic sarcodines (Acantharia Radiolaria and Foraminifera) in surface waters near Bermuda abundance, biomass and vertical flux, J. Plankton Res., 17, 131, 1995. 

Knowledge of the relative role of vaporization in pesticide field dissipation has been markedly advanced by development of methods for measuring the vertical flux of vapors from a soil or soil-crop field plot. The basis and techniques for this method have been presented by Caro et al.(74) and Parmele et al. (7), and summarized recently by Taylor (6). The equation... 

The high vertical flux of particulates in river/estuarine plume regions commonly results in the accumulation of particles in the formation of a benthic boundary layer (BBL) and/or mobile and fluid muds (see chapter 6 for more details). The BBL is defined by Boudreau and Iprgensen (2001, p. 1) as those portions of sediment and water columns that are affected directly in the distribution of their properties and processes by the presence of... 

Axelman, J., Broman, D., and Naf, C. (2000) Vertical flux of particulate/water dynamics of polychlorinated biphenyls (PCBs) in the open Baltic Sea. Ambio 29, 210-216. 

Colombo, J.C., Silverberg, N., and Gearing, J.N. (1996a) Biogeochemistry or organic matter in the Laurentian Trough. I. Composition and vertical fluxes of rapidly settling particles. Mar. Chem. 51, 277-293. 

The property of chemotropicity testifies to the balance of the redox layer system with respect to the vertical fluxes of the oxidants and reductants supplied. This should be the well-defined sequence of changes with depth of the favorability of the potential redox reactions [ 17,75] that can be realized by the bacterial community. The development of bacteria in this case should affect the distributions of nutrients. By modern estimation [79] the chemosynthetic production is comparable with photosynthetic production, and that should in the same manner affect the consumption of inorganic nutrients and production of their organic forms. Besides this the possible abiotic chemical reactions and the sedimentation of particulate matter of different densities should also play their roles in this mechanism. 

---