CHAPTER 7 . Sedimentary Geochemistry of the Carbonate and Sulphide Systems
+
Organic
~
matter
-----'L:J
+
167
r-;:I
+~
Bacteria 1
1 Bacteria 1
[:J
,
. +1 ~, I
+
+
HCOJ ,w
HP~- ,NHt
+
~
~
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101
+
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Bacteria
0
~
+
m
+
I:I~ 1 I
I c>" II c.co, I u
I res,
1 1
[
CaC03
I I Ca 2 +, HCO) I
Fig. 7.2. A schematic representation of the sedimentary sulphur-carbon system
unity (see Goldhaber and Kaplan 1974; Morse et al. 1987; Morse and Mackenzie 1990;
and Rickard et al. 1995 for literature reviews and discussions on this topic).
Gas-Liquid Equilibrium:
COZ(g) H COZ(aq)
K H,c02 = aC0 2 (aq) I fc0 2 = 3.39 x 10- Z
(7.1)
HzS(g) H HzS(aq)
KH,H 2 S = aH 2 S(aq) I fH 2 S = 10.2 X 10- Z
(7.2)
First Acid Dissociation Constant:
COZ(aq) + HzO H HCO; + H+
K]'C0 2 = (aHCOj" aH+) I aC0 2 (aq) = 4.47 x 10- 7 (7.3)
HzS H HS- + H+
K1,H 2 S = (aHS- aH+) I aH 2 S(aq) = 1.05 x 10- 7
(7.4)