Environmental Engineering Reference
In-Depth Information
Table 13.
Alkalinity and dissolved calcium content in pore waters, sulfate reduction rate
(SRR) and the carbon isotopic composition of organic carbon, HCO
3
−
and calcium carbonate in
shallow-water sediments of the north-western shelf of the Black Sea [70].
Ca
2
+
,
Station/
Sediment
SRR
Alka-
δ
13
C,
‰
HCO
3
−
water
layer, cm
µ
mol
linity,
mg
C
org
CaCO
3
dm
−
3
l
−
1
depth
mM
day
−
1
11/
0-1.0
73.1
4.5
-
-25.2
-18.6
-10.9
11m
0.5-8.0
6.3
8.5
-
-25.4
-18.0
-11.4
9.0-14.0
9.9
12.5
-
-26.9
-19.0
-10.5
21.0-25.0
-
18.0
-
-25.9
-22.0
-8.6
16/
0-1.0
12.8
4.0
14.0
-24.1
-
-11.8
16m
1.0-6.0
5.6
5.0
12.0
-24.9
-
-13.8
8.0-12.0
21.3
14.0
12.0
-25.5
-
-10.8
20.0-30.0
5.9
25.0
9.0
-25.6
-
-11.3
30.0-40.0
-
-
5.0
-26.0
-
-11.3
1/
0-3.0
-
3.5
-
-
-
-
55m
4.0-5.0
2.6
3.8
-
-23.5
-
-4.3
7.0-20.0
1.7
3.9
-
-24.2
-
-2.7
20.0-25.0
6.4
4.1
-
-24.3
-
-7.0
-11.4
∗
28/
0-13.0
5.5
2.2
-
-26.3
-2.1
129m
20.0-26.0
2.2
4.0
-
-25.5
-2.2
∗
For sediment layer 0-26.0 cm
13
C=-27‰ (Table 8) and 44% of planktonic and bacterial origin with
the average isotopic composition of organic carbon of -23‰.
Local variations of the isotopic composition of POC in the chemocline zone
due to carbon fractionation by autotrophs and insignificant enrichment of DOC
with the light isotope
12
C in the deep water column as a result of heterotrophic
microbial activity have little effect on the carbon isotope cycle of the Black
Sea.
with δ
6. FRACTIONATION OF CARBON ISOTOPES
DURING THE METHANE CYCLE IN THE BLACK
SEA
The biogeochemical methane cycle in the Black Sea is less understood in
comparison with the sulfur cycle, particularly the isotopic composition of car-
bon and hydrogen of the Black Sea methane and products of methane oxidation.
Before cold methane seeps [83] and associated with them carbonate construc-
