Spatial and temporal patterns of ocean acidification during the end-Permian mass extinction – an Earth system model evaluation - Volcanism and Global Environmental Change - page 293

Table 19.1 Initial conditions speci ed for cGENIE in this study

Parameters Description Value Units

Ω calcite, init

Calcite surface saturation state 2.5, 5 and 10 Dimensionless

pH init Ocean surface pH 7.7 ( Ω calcite, init ¼ 10) Dimensionless

7.55 ( Ω calcite, init ¼ 5)

7.4 ( Ω calcite, init ¼ 2.5)

C

T 0 Global average ocean surface

temperature

21

Tmol yr - 1

F w, calcite Weathering flux of calcite 17

Tmol yr - 1 F w, silicate Weathering flux of silicate 10.5

13 C w 13 C of weathering calcite

δ δ 3.6 ‰

13 C outgassing 13 CofCO 2 from volcanic

outgassing

δ δ 3.6 ‰

13 C atm 13 C of atmosphere

δ δ 5 ‰

13 C DIC 13 C of DIC in surface ocean

δ δ 2.9 ‰

[Ca 2 þ ] Ca 2 þ concentrations in the

ocean

mmol kg - 1 13

p CO 2init Initial atmospheric p CO 2 2800 ppm

10 18 0.5 mol

mol kg - 1 [DIC] surf Surface ocean DIC

concentration

6035 ( Ω calcite, init ¼ 10) μ

4230 ( Ω calcite, init ¼ 5)

2970 ( Ω calcite, init ¼ 2.5)

mol kg - 1 [DIC] deep Deep ocean DIC

concentration

6304 ( Ω calcite, init ¼ 10) μ

Ω calcite, init ¼

4450 ( 5)

3160 ( Ω calcite, init ¼ 2.5)

end-Permian extinction (Cui et al ., 2013 ). With a desired global mean surface
saturation value (e.g. gured to

determine the appropriate initial ocean alkalinity (Alk) and DIC value (the initial
conditions of the model are summarized in Table 19.1 ).

Ω ¼ 10, 5 and 2.5), cGENIE can be con calcite

19.2.3 Forcing the DIC with CO 2 addition
We used the carbonate C isotope record of the GSSP (Global Boundary Stratotype
Section and Point) in Meishan, South China (Shen et al ., 2011 ) to perform a loess

fit (Matlab ® smoothing function “ loess ” ), where a span parameter of 8% was

speci ed, lower than that used in Cui et al .( 2013 ), to capture a larger magnitude

of CIE ( Figure 19.1 ). We then forced the ocean-surface DIC

13

δ C to conform to the

13 13

prescribed δ C DIC derived from the statistically treated δ C carb , using an offset of

0.6 meant to account for the difference between the DIC and sedimentary

CaCO 3

‰

13 13

C values of added CO 2 such that they represent
several proposed sources, including plume-released CO 2 (

δ C. We varied the δ

- 9 ‰ and - 12 ‰ ), CO 2

‰ - ‰

from mixed sources ( - 15 and 20 ), contact metamorphism of coal and

- ‰ - ‰

kerogen ( 25 ), CO 2 from oxidation of thermogenic methane ( 40 ) and