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Re: phreeqc-alkalinity



That´s fine. Many thanks for the short and helpful comments focused on alklinity!!!
Is there an interface between PHREEQC and DYRESM?

René

David L Parkhurst wrote:
> 
> For Fe(3), a speciation calculation indicates that the predominant species
> is Fe(OH)2+ at pH 4.5. We chose Fe+3 to have an alkalinity of -2 so that
> Fe(OH)2+ would have an alkalinity of zero.
> 
> David
> 
> David Parkhurst (dlpark@xxxxxxxx)
> U.S. Geological Survey
> Box 25046, MS 413
> Denver Federal Center
> Denver, CO 80225
> 
> Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled
> 
> 
>                       Rene Froemmichen
>                       <Rene.Froemmichen@xxxxxxxxxx        To:       David L Parkhurst <dlpark@xxxxxxxx>
>                       gdeburg.DE>                         cc:
>                                                           Subject:  Re: phreeqc-alkalinity
>                       07/09/03 09:27 AM
> 
> 
> 
> Dear David,
> 
> I agree completely with you, including ANC and BNC definition. Furthermore
> in real systems dynamics
> and kinetics are very important to reach the so called reference point.
> However, why Fe(3) hasn´t
> got -3 as alkalinity in the phreeqc.dat?
> 
> René
> 
> David L Parkhurst wrote:
> >
> > > I have a a problem with phreeqc calculation of alkalinity in strongly
> > acidified mine pit lake water. The main constituents in well oxygenated
> > surface water are Fe(3)-1.55mM, Al-1.24 mM and S(6)-13mM. The pH is given
> > with 2.7. Phreeqc is calculating an alkalinity of -5.88e-03 eq/L. In my
> > opinion this cannot be correct. Because of the infinite low CO2
> > concentration the alkalinity (alk) is defined via
> >
> > alk=-[H+]-aci[Fe-species]-aci[Al-species]-[HSO4-],
> >
> > > isn´t it? I´m calculating -8.21e-03 eq/L.
> >
> > > What about your ideas to solve this problem?
> >
> > PHREEQC does just as you indicate, except that each aqueous species is
> > assigned an alkalinity. Not all Fe+3 species have the same alkalinity,
> nor
> > do all the Al+3 species. PHREEQC assigns an alkalinity to each of the
> > master species (SOLUTION_MASTER_SPECIES data block). Alkalinities for the
> > aqueous species are derived from the alkalinities assigned to the master
> > species by using an equation that does not contain e- (probably can not
> > have O2 or H2 either). For example:
> >
> > Fe+3 is a master species assigned an alkalinity of -2 in phreeqc.dat; H+
> is
> > -1; H2O 0. Using the eqn Fe+3 + H2O = FeOH+2 + H+, FeOH+2 has an
> alkalinity
> > of -1. After you have the alkalinity assigned to each aqueous species,
> sum
> > the alkalinity times the molality of each species to get the alkalinity
> > that PHREEQC calculates.
> >
> > There is some ambiguity because of the pK of each hydrolysis species and
> > the assignment of integral alkalinities to the master species; a species
> > may not be completely titrated in an acidity titration. You may want to
> > simulate a titration and look at the difference in the calculated
> > alkalinities, which might give a more accurate value. In any event, there
> > is some ambiguity in the definition of alkalinity, because it refers to
> an
> > acid neutralizing capacity relative to a reference state (see Stumm and
> > Morgan).
> >
> > David
> >
> > David Parkhurst (dlpark@xxxxxxxx)
> > U.S. Geological Survey
> > Box 25046, MS 413
> > Denver Federal Center
> > Denver, CO 80225
> >
> > Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled
> 
> --
> --------------------------------------------------------------
> Otto-von-Guericke-University
> Chair for Process System Engineering
> Max-Planck-Institute for Dynamics of Complex Technical Systems
> Physical and Chemical Process System Engineering
> Dr. René Frömmichen
> 
> c/o
> Institute for Chemistry
> Universitätsplatz 2
> 39106 Magdeburg
> Germany
> 
> tel +49 (0)391 67 12594
> fax +49 (0)391 67 12223
> e-mail rene.froemmichen@xxxxxxxxxxxxxxxxxxxx
>        froemmic@xxxxxxxxxxxxxxxxxxxx
> --------------------------------------------------------------

--
--------------------------------------------------------------
Otto-von-Guericke-Universität
Lehrstuhl für Systemverfahrenstechnik
Max-Planck-Institut für Dynamik Komplexer Technischer Systeme
Physikalisch-Chemische Prozesstechnik
Dr. René Frömmichen

c/o
Institut für Chemie
Universitätsplatz 2
39106 Magdeburg

Otto-von-Guericke-University
Chair for Process System Engineering
Max-Planck-Institute for Dynamics of Complex Technical Systems
Physical and Chemical Process System Engineering
Dr. René Frömmichen

c/o
Institute for Chemistry
Universitätsplatz 2
39106 Magdeburg
Germany

tel +49 (0)391 67 12594
fax +49 (0)391 67 12223
e-mail rene.froemmichen@xxxxxxxxxxxxxxxxxxxx
       froemmic@xxxxxxxxxxxxxxxxxxxx
--------------------------------------------------------------


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