geochemistry of carbon cycles on rocky exoplanetsgeochemistry of carbon cycles on rocky exoplanets...
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GeochemistryofCarbonCyclesonRockyExoplanets
KaustubhHakim1,DanJ.Bower1, MengTian1,RussellDeitrick1,PierreAuclair-Desrotour1,DanielKitzmann1, CarolineDorn2, KlausMezger3, KevinHeng1
ALithology-basedSilicateWeatheringFramework
1 UniversityofBern,CenterforSpaceandHabitability,Gesellschaftsstrasse 6,3012Bern,Switzerland2 UniversityofZurich,InstituteforComputationalScience,Winterthurerstrasse 190,8057Zurich,Switzerland
3 UniversityofBern,InstituteofGeology,Baltzerstrasse 1+3,3012Bern,Switzerland
WHY?• Thelong-termcarboncycle(carbonate-silicatecycle)providestheessentialnegativefeedbackinmaintainingtemperateclimatesonEarth[1]*
• Silicaterocksonexoplanetsarelikelytobediversethanpresent-daycontinents
• Previousstudiesmodelthesensitivityofweatheringratesonthepartialpressureofcarbondioxide!"#$ usingreactionratecoefficientsbasedonchemicalkinetics
Weatheringrate∝ !"#$% [1]
• Exampleweatheringreaction:
• Equilibriumchemistryalsoallowsdetermining& [2]
@exokaustubh
http://www.exokaustubh.com
WHAT?
KEYFEATURES• Estimatesofweatheringfromfirstprinciplesofchemistry
• Applicabletobothseafloorandcontinentalsilicateweathering
HOW?• Wetrackthetotaldissolvedinorganiccarbonatchemicalequilibrium(DIC*+)DIC*+ = CO. /+ + [CO2.3] + [HCO23]
HIGHLIGHTS• Thesensitivity(&)oftheweatheringfeedbackto!"#$ isnotconstantasassumedbypreviousstudies
• Itisastrongfunctionoflithologyand!"#$
• Ourframeworkisbasedongeochemicalreactionsandextendabletonon-silicateweatheringandatmospheresdenserormoredilutethanthatofEarth
References[1]Walker,Hays&Kasting (1981),J.Geophys.Res.,86,9776[2]Winnick&Maher(2018)EPSL485,111-120*OtherreferencesareomittedforclarityofthispresentationIllustrationcredit:JennyLeibundgut
CaSiO3(s) +2CO2(aq) +H2O↔Ca2+ +2HCO3– +SiO2(aq)
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