esm222_18_fate&transport

esm222_18_fate&transport - ESM 222 Fate and...

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1 © Arturo A. Kel er ESM 222 Fate and Transport: Bringing together all the pieces 2 © Arturo A. Kel er Fate and Transport ± We now have the pieces to put together a conceptual and a simple numerical model of fate and transport of a pollutant in the environment: ± what moves it through the environment ± where is it going to end up ± how fast will it get there ± how long will it last in the environment 3 © Arturo A. Kel er Fate and Transport ± We go back to our advection/dispersion equation, which considers the change in mass of a pollutant in the environment: (assuming the pollutant is dissolved in water) ) O I ( * F * F * F x C D x C v t C V react solid gas 2 2 x x + ± + = 4 © Arturo A. Kel er Fate and Transport ± F* gas = Flux from water to gas, controlled by the concentration gradient, the diffusivity, the equilibrium ratio (K H ) and the thickness of the layers = [kg/d] . (We know the contact area) ± Same idea for other fluxes ± F* react = reaction or sum of reactions, including biodegradation, in [kg/d] ± I = input of pollutant to the system, [kg/d] ± O = output of pollutant from the system, [kg/d] ± V = volume of system [m 3 ] 5 © Arturo A. Kel er Fate & Transport ± Pulse Release in Groundwater () ) t k exp( t D 4 t v x exp t D 4 M ) t , x ( C deg ' x ' 2 x ' x i i = π To account for retardation: D’ x = D x /R v’ x = v x /R k’ deg = k deg /R 6 © Arturo A. Kel er Fate and Transport ± Example: PCE into a lake (Greifensee) I O F gas F solid F react
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7 © Arturo A. Kel er Fate and Transport V = total volume = 150 x 10 6 m 3 A = surface area = 8.6 x 10 6 m 2 h = mean depth = V/A = 17.4 m Q = throughflow of water = 0.34 x 10 6 m 3 /d t w = mean water residence time = V/Q = 440 d • Example: PCE into a lake (Greifensee) 8 © Arturo A. Kel er Fate and Transport ± From direct measurements we obtain the additional information: C w = conc. of PCE in lake = 91 x 10 -6 g/m 3 I = River input = 0.149 kg/d O = Loss at outlet = 0.030 kg/d F* react = degradation of PCE ~ 0 F* solid = sorption of PCE ~ 0 9 © Arturo A. Kel er
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This note was uploaded on 08/06/2008 for the course ESM 222 taught by Professor Keller during the Spring '08 term at UCSB.

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esm222_18_fate&transport - ESM 222 Fate and...

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