Export coefficients

Keywords Export coefficients. Nutrients, Temporal trend, Water quality, Weathering... 

Export coefficients per unit area of the catchment and per unit time characterize the mass flow (load) of a river water constituent at the outlet of the catchment. For conservative constituents, that is for which no relevant biogeochemical transformation processes are occurring in the river water, the export at the outlet is equal to the sum of all inputs into the river coming from the various point and diffuse sources. This assumption can be regarded as a valuable approximation in alpine rivers for most of the chemical parameters discussed. Export coefficients allow comparing different catchments in size, land use, or other characters describing a basin. 

Table 3 Export coefficients for water, nutrients, and suspended solids...

Zobrist J, Reichert P (2006) Bayesian estimation of export coefficients from diffuse and point sources in Swiss watersheds. J Hydrol 329 207-223... 

If the DMS inventory in Salt Pond is at steady state in summer (5), production should approximately balance removal. Tidal removal of DMS to Vineyard Sound is minimal. Outflow from Salt Pond is thought to be primarily surface water, and using a maximum tidal range of 0-0.2 m/d and a mean surface water concentration of 10 nmol/L, we calculate an export rate of less than 2 /imol/m2/d. The water-air flux of DMS may be calculated using the two film model of liss and Slater (22 flux = -ki C, ). With the same surface water DMS concentration (C ) and an estimated mass transfer coefficient (ki) for DMS of 1.5 cm/h, the projected flux of DMS from the pond into the atmosphere would be 4 /unol/m2/d. This compares with the range of estimated emissions from the ocean of 5-12 /imol/m2/d (1). 

Fig. 12.4 Effects of the depth resolution in pore water concentration profiles on calculating the rates of diffusive transport. Three samples drawn from surface sediments are shown to possess different resolutions (intervals 0.5 cm - dots, 1.0 cm diamonds, 2.0 cm - squares). All values are sufficient to plot the idealized concentration profile within the hounds of analytical error, yet very different flux rates are calculated in dependence on the depth resolution values. In the demonstrated example, the smallest sample distance indicates the highest diffusion (2.98 mmol cmA f ). As soon as the vertical distance between single values increases, or, when the sediment segments under study grows in thickness, the calculated export across the sediment-water boundary diminishes (2.34-t.64mmol cm yr ). In our example, this error which is due to the coarse depth resolution can be reduced by applying a mathematical Fit-function. A truncation of 0.05 cm yields a flux rate of 2.84 mmol cm yr. (The indicated values were calculated under the assumption of the presented porosity profile according to Pick s first law of diffusion - see Chapter 3. A diffusion coefficient of 1 cmA f was assumed. Adaptation to the resolution interval of 2.0 cm was accomplished by using a simple exponential equation).

Circulation Mixing coefficients Air-sea fluxes Export production Particle fluxes... 

Total export of individual PAH compounds was calculated by the weighted export of the individual PAH compounds. As weighting factor, the probability of a specific combination of soil profiles and contamination level was chosen. The weighting factor is thus given by the probability of occurrence as obtained by the stochastic reconstruction of the soil profiles. For all selected PAH the observed export varied by more than 4 orders of magnitude (Fig. 1.7). Export decreases in the order of Phenanthrene > Benzo(k) fluoranthene > Pyrene > Benzo(a)pyrene. Due to the linear relations of the partition coefficients, the export of the individual PAH is proportional to both the... 

Where Q = Gas seepage flow Pa = the atmospheric pressure L = Length of the specimen PI = Specimen inlet gas pressure P2 = Specimen export gas pressure A = he cross-sectional area of specimen = the gas viscosity coefficient. 

The Islamic Republic of Iran submitted the results of 6187 AFL monitoring data for 1849 pistachio nut lots (ready-to-eat) consigned to be exported from July 2004 to March 2007 (Secretariat of Iran Codex Committee on Contaminants in Food, 2007). The sensitivity of the analytical method was reported with an LOD of 0.2 pg/kg for AFBi and 0.4 pg/kg for AFT, with 24% of the data reported below the LOD. A linear regression coefficient of 1.13 (similar to the number reported in the EFSA opinion) was applied to estimate the level of AFT in a low number of samples (around 4%) in which AFBi data only were submitted. 

Cf marginal fuel price Cp imported or exported power price Cy valve orifice coefficient / objective function FE fuel equivalent h enthalpy m, M mass flow... 

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