PHREEQC lecture.docx
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PHREEQC lecture.docx
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PHREEQClecture
PHREEQC
GettingStarted:
Downloadprogramatthefollowingwebpage:
HTTP:
//wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc
∙Readthroughinformationonwebpage.Thereismuchusefulinformationincludingmultipleversion(PC,Mac,Linux)andhelpinformation
∙Downloadthemostcurrentversion.Asofthisdate,theversionis
oPhreeqcIversion3.0.1-7561(16M),lastupdatedFebruary1,2013
∙Note:
Phreeqcisupdatedoften.Besuretousethemostrecentversion.Therealsomaybeanissuewithaconflictwithwindows.Ifso,thereisasimpleexplanationforhowtodownloadapatchonthedownloadpage.
AfewexamplesofthingsthatPHREEQCcando.
Thesenotesprovideafewexamplesofwhattheprogramcandointermsofcalculationsofwaterchemistry,water-rockinteractions,andspeciationofwater.Theprogramhasmanymorefunctions,butitisintuitiveandeasytouseandonceyouareabletoinputdataandextractresults,youwillbeabletorunmanytypesofsimulations.Thereisalsoaverygoodmanualwithmultipleexamplesthatyoucanworkthroughtodevelopothersimulationstotry.
I.Calculatesaturationstates,complexation,andspeciespresentgivesomewatercomposition:
Givenwaterwiththefollowingcomposition:
Solution1.
Ion
Conc.(mg/L)
Ion
Conc.(mg/L)
Ca
48
Cl
8.0
Mg
3.6
NO3
0.3
Na
2.1
Fe
0.05
K
1.2
pH
7.5
HCO3
152
T
20
SO4
3.2
Questionstobeaddressedaboutthiswater:
(1)Whatcomplexesandspeciesarepresentinthewater?
(2)Whataresaturationstatesofvariousminerals?
A.Procedure:
(1)Clickon“Solution”button(apictureofasmallflask)
(2)Fillindatawhereneeded.Forthisexample,youwillfirstprovideTandpHunderthefirsttabonthesheet.Thenmoveto“individualelementinput”tab.Includeallthedata.
Note:
a)besuretoincludecorrectunits.Youmayuse“DefaultUnits”orprovideunitsindividually.AllofPhreeqccalculationsandreportsaremolarconcentrations.Theprogramwillautomaticallyconverttomolarunitsforyou.
b)Youmaycalculatethechargebalance,ormaycorrectforchargebalancewithsomeion,forexamplebicarbonateifyouaremissingthatanalysis.
(3)Placecursorinthewindowontherightwindow.Thiswindowshouldnowshowthevaluesofthedatathatyouhaveinput.Thiswillhighlighttheblue“Run…”button.Clickbutton.Youmaybepromptedtosave,orifyouhavepreviouslysavedthefile,itwillwarnyouthatyouwilloverwritethepreviousfile.
(4)ClickStart.Thecalculationswillbemade.Clickdismiss.Atthispointthetabsatthebottomoftheleftpagewillchangefromblue“input”tabtogreen“output”tab.Anddatawillbeshown.
B.Results:
Whenyoushifttotheoutputtab,youwillbeabletoopenfoldersbyclickingonthe“+”symbolnexttoanyfolder.Openingthefoldernexttothe“Beginningofinitialsolutioncalculation”givesanotherfolderthatisthe“Initialsolution1”.Thiswillopenupandallowaccesstothefoursectionsofthedataresultsincluding:
Solutioncomposition
DescriptionofSolution
DistributionofSpecies
Saturationindices
Byclickingonanyoneofthesebuttonswilltakeyoutothatpointofthedataresults.Theuppermostportionofthefilerepeatsthedatathatwasinputasadescriptionofthewater.Forexample,clickingontheSaturationindicesbuttonwilltakeyoutothebottomoftheresultswhereyouwillbethefollowingfile:
------------------------------Saturationindices-------------------------------
PhaseSIlogIAPlogKT
Anhydrite-3.36-7.72-4.36CaSO4
Aragonite-0.11-8.44-8.34CaCO3
Calcite0.04-8.44-8.48CaCO3
CO2(g)-2.24-3.70-1.47CO2
Dolomite-0.70-17.79-17.09CaMg(CO3)2
Gypsum-3.14-7.72-4.58CaSO4:
2H2O
H2(g)-23.00-26.15-3.15H2
H2O(g)-1.51-0.001.51H2O
Halite-9.33-7.751.58NaCl
Melanterite-8.74-10.95-2.21FeSO4:
7H2O
O2(g)-37.19-40.08-2.89O2
Siderite-0.78-11.67-10.89FeCO3
Thisfileshowseachpossiblemineralphase,it’sSaturationIndex,thelogoftheionactivityproduct(IAP),andthelogoftheequilibriumconstantforthetemperatureofthewater(KT).Thelastcolumnisthestoichiometryofthemineralphasethatisequilibrium.
Forexample:
onthispage,aragoniteisslightlyundersaturated(SI=-0.11),butCalciteisslightlyoversaturated(SI=0.04).
Abovethisfilewillbeatableofdata.Forexample:
LogLogLog
SpeciesMolalityActivityMolalityActivityGamma
Ca1.198e-003
Ca+21.155e-0038.748e-004-2.937-3.058-0.121
CaHCO3+3.322e-0053.099e-005-4.479-4.509-0.030
CaCO36.046e-0066.052e-006-5.219-5.2180.000
CaSO43.813e-0063.817e-006-5.419-5.4180.000
CaOH+4.929e-0094.590e-009-8.307-8.338-0.031
CaHSO4+7.592e-0137.071e-013-12.120-12.150-0.031
Thistableshowsallofthepossiblespeciesinthesolution,theirconcentrations(molality),activities,logmolalities,logactivitiesandlogactivitycoefficients.
Forexample,theCaconcentrationsisabout1.2x10-3molarandthereareseveraldissolvedspeciespresentincludingCaHCO3(3.322x10-5molar),CaCO3(6.046x10-6molar),CaSO4(3.813x10-6molar)etc.
II.ChangingDatabases
WhenyourantheprograminpartI,oneofthemenuitemsthatpoppedupwascalledRun.ThatmenugaveyoutheoptionofindicatingwhichInputfile,OutputfileandtheDatabasefiletorun.Thedatabaseincludesallthethermodynamicdatausedtomakethesaturationcalculationsandparametersforestimatingtheactivitycoefficients.Tochangethedatabaseusedinthecalculations,doubleclickontheradiobuttonwiththethreedotslocatedtotherightofthescrolldownmenu.ThisbuttonwillopenthePhreeqcInteractivefoldertothegroupof.datfiles.Thedefaultfileissettophreeqc.dat,butyoushouldhaveachoiceofseveralothers.Youwillalsohavetheoptionofresettingthedefaultfiletoany.datfileyouchoose.Thedifferentfileshavebeencompiledforotherspeciationsoftware,otherlaboratories,orgatheredfromtheliterature.
Youmaylookatthestructureofthe.datfilesandchangethemdirectlyinthefiles.GotoMyComputer,intheCdriveandlookforPhreeqcInteractivefolder.Note:
thisfoldermaybelocatedinafolderlabeledUSGS.OpenthePhreeqcInteractivefolderandthereshouldbeseveral.datfilesalongwiththephreeqci.exefile,afolderwithexamples,anddocfolderwiththehelpmanual,amongothers.Rightclickoneofthe.datfilesandopenitwiththeWordPadprogram.Inthisfileyouwillfindallthesolutionsspecies,logKvalues,coefficientsforcalculatingactivitycoefficientsusingtheDebye-Huckelformula.Althoughyoucanchange,add,ordeleteparametersinthisfile,itissafertodothisthroughtheprogramwhenaddingdatatosimulate.
Dothefollowingproceduretoobservehowmuchthedatabasechanges.
(1)Withthedatathatwasinputassimulationone,runthesimulationagain,butthistimechangethe.datfiletothellnl.dat(datafromLawrenceLivermoreNationalLaboratory).
(2)ScrolldowntotheSaturationindicestoobservecalculationsofsaturationstatesofthevariousminerals.Youwillseeseveralthingshavechanged,includinganincreaseinnumberofmineralsforwhichsaturationstateshavebeenestimated.Thisincreaseresultsfromagreateramountofelementaldatainthellnl.datfiles.Saturationstatesofthemineralshavealsochanged,forexample,SIaragoniteisnow-0.16,downfrom-0.11.Fordolomite,therearenowcalculationsofdifferenttypesincludingstoichiometricdolomite,ordereddolomiteanddisordereddolomite.
III.Whathappensiftwowaterswithdifferentcompositionsmix?
Givenanotherwaterwiththefollowingcomposition:
Table2.Solution2
Ion
Conc.(mg/L)
Ion
Conc.(mg/L)
Ca
96
Cl
16.0
Mg
7.2
NO3
0.6
Na
4.2
Fe
0.1
K
2.4
pH
8.0
HCO3
304
T
25
SO4
6.4
A.Somequestions:
(1)Whatisthecompositionofwaterderivedfrommixingspecifiedamountsoftwodifferentkindsofwater?
(2)Whataresomeofthespeciespresentinthemixedwater?
(3)Howdothesaturationstatesofvariousmineralschange?
B.Procedure:
(1)Gobacktothe“input”tabonthelowerleftwindow.
(2)Highlight“simulation”fromthefirstsimulation.Placean“end”attheendofthesimulationbyclickingontheblackdotinthemenu.
(3)Makesurethat“end”ishighlightedandclickonthesolutionbuttononcemoretoincludeasecondsolution.Inputthedataintothespreadsheetforthissolutionsimilartothefirstsolution.
(4)Highlight“end”againandclickonthemixbutton–aredvolumetricflaskwithaplus(+)connectedtoit.Amenuwillopenandshouldshowradiobuttonstohighlightbothsolutions.
(5)Clickonthefirstandsecondsolution.Itwillgiveavalueof1forthemixingproportionsforeachwater.Thismixingsolutionessentiallyrepresents1Lforeachsolution(e.g.50%ofeach).Youcanchangetheproportionstoanyproportionyouwish–itdoesnothavetoaddto100%.Inthisexample,themixingproportionis“4”ofsolution1and“1”ofsolution2.(e.g.80%solution1,20%solution2).
(6)Placecursorinthewindowontheright.Thiswillhighlighttheblue“Run…”button.Clickbutton.Youmaybepromptedtosave,orifyouhavepreviouslysavedthefile,itwillwarnyouthatyouwilloverwritethepreviousfile.
(7)ClickRun.Thecalculationswillbemade.Atthispointthetabsatthebottomoftheleftpagewillchangefromblue“input”tabtogreen“output”tabanddatawillbeshown.
C.Results:
Openthefoldercalled“ReadingInputDatafromSolution1”.Ifyouopenallthefilesitwillallowyoutolookthroughallthecalculations,whichwillshowthespeciationsofthetwosolutions,andsaturationstatesofallpo
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