Geochemistry of Carbon Cycles on Rocky ExoplanetsGeochemistry of Carbon Cycles on Rocky Exoplanets...
Transcript of Geochemistry of Carbon Cycles on Rocky ExoplanetsGeochemistry of Carbon Cycles on Rocky Exoplanets...
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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