X position (m) I s o t p i c m n C , d a y Bulk fluid CO (aq)

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Presentation transcript:

X position (m) I s o t p i c m n 1 3 - C , d a y Bulk fluid CO (aq) 2 4 6 8 10 – 20 15 5 X position (m) I s o t p i c m n 1 3 - C , d a y Bulk fluid CO (aq) Calcite HCO

Specify domain’s starting fluid composition on the Initial pane Alkaline fluid in equilibrium with calcite Aquifer is 70% calcite by volume

The inlet fluid is defined on the Fluids pane Acidic inlet fluid “infilter” Equilibrium with atmospheric CO2

Specify flow rate on the Flow pane. Set specific discharge or hydraulic head/ potential drop

Simple kinetic rate law for calcite dissolution Define simple and buffered reactants and kinetic reactions on the Reactants pane Simple kinetic rate law for calcite dissolution

Specify domain size and gridding on the Domain pane. Domain is 10 m long, divided into 40 nodal blocks

Inlet fluid “infilter” enters the domain from t = 0 to 30 days Define the reaction intervals. Specify what fluids flow into the domain, and when. Inlet fluid “infilter” enters the domain from t = 0 to 30 days

Config → Isotopes… Run → Go Calcite is segregated from isotopic exchange Isotopic composition d13C of the initial fluid Initial d13C of segregated mineral calcite d13C of the inlet fluid “infilter” Run → Go traces the model

In absence of precipitation, composition of segregated calcite is unchanged Calcite dissolution makes bulk fluid heavier as it moves through domain. δ13C of fluid changes from composition of CO2(aq), the predominant species at low pH near inlet, toward that of HCO3−