Environmental Engineering Reference
In-Depth Information
5. THE ISOTOPIC COMPOSITION OF CARBON IN
BOTTOM SEDIMENTS
Published data on the isotopic composition of organic carbon are listed in
Table 12, which shows that seasonal differences in the isotopic composition are
found only in the uppermost sediments on the north-western shelf: abundance of
terrigenous organic matter in April-May shifts the average isotopic composition
of organic carbon by -1.7‰ compared to the data obtained in August (Table
12, No. 1 and 3).
Table 12.
The carbon isotopic composition of organic matter in surface sediments of the Black
Sea.
13
C,
‰
Place of
Time of
δ
Reference
sampling
sampling
-25.15
∗
1
North-western
August
[70]
shelf, 0-1 cm
−
24.3
÷−
26.0 [2]
2
North-western
May
-26.8
[50]
shelf, 0-1 cm
−
24.8
÷−
27.5 [5]
3
North-western
August
-23.8
[32]
shelf, 0-1 cm
−
22.5
÷−
26.5 [15]
4
North-western
August
-25.3
[70]
shelf, 0-40 cm
−
24.2
÷−
26.9 [21]
5
Deep-sea,
October
-25.7
[67]
>
as 2000 m,
−
25.5
÷−
26.0 [11]
4 Stations, 0-10 cm
6
Deep-sea
-
-24.4
[12]
2 stations, 0-40 cm
−
24.0
÷−
25.6 [14]
7
Continental slope,
-
[59]
÷
0-60 cm
-23.4
-25.7 [15]
∗
Numerator - the average δ
13
C, ‰;
13
C; number in brackets - number of samples.
denominator - range of δ
13
C of organic carbon in sediments on the north-western
shelf (Table 12, No. 3) is close to published data ([59]; Table 12, No 7). They
are however in contradiction with the Galimov's opinion [31, 32] on certain
zonality of δ
The range of δ
13
C distribution in sediments from various geochemical zones of
the Black Sea. His results were based on a small number of samples in the
uppermost (0 - 1 cm) sediments collected in summer. In summer isotopically
heavy organic matter of the planktonic origin accumulates in shallow regions.
However, this organic matter is quickly degraded, therefore the isotopic com-
position of organic matter from the shelf sediments is slightly different from
