Environmental Engineering Reference
In-Depth Information
(CTD-064: 44
◦
14'N, 32
◦
30'E, 1658 m, Fig. 1). Water samples were taken
with a rosette system equipped with 10 l Niskin bottles. To sample the gas
plume at the seep stations, the vessel was either anchored (shallow water) or
the rosette was fired while drifting over the plume site, after careful mapping
of the plume dimensions using side scan sonar (deep stations). Oxygen profiles
were recorded using a CTD system calibrated by Winkler titration.
30°
35°
40°
46°
46°
055
038
Sevastapol
072
064
44°
44°
7617
7605
42°
42°
7623
Istanbul
Samsun
40°
40°
30°
35°
40°
Figure 1.
Map of the Black Sea showing sampling stations. Stations 7605 (central basin),
7617 (north-western slope), and 7623 (south-western slope) were sampled during the Meteor
cruise in 2001 and Stations 038 (seep site on the north-western shelf), 055 (reference site on the
north-western shelf), 064 (reference site on the lower slope southwest of Crimea), and 072 (seep
site on the lower slope south of Crimea) were sampled during the CRIMEA cruise in 2003.
2.2 Methane Concentration and Isotopic Composition
For water sampling, 120 ml serum bottles were filled from the Niskin bottle
directly after retrieval of the rosette. The water samples were poisoned with
NaOH pellets, crimped immediately with a butyl-rubber stopper, and kept in
the dark at 4 to 8 degrees. In the laboratory, a 20 ml helium headspace was
introduced and equilibration between both phases was achieved. For sediment
sampling a 5-mL cut-off plastic syringe was inserted through small holes in
the core liner and the samples were placed in 50-mL serum vials containing
6 mL of 2.5 % NaOH solution. These vials were crimp sealed with butyl-rubber
stoppers, shaken, and allowed to sit at room temperature for some hours before
the measurement. Quantification of methane was accomplished by injecting
1 to 5 mL of headspace from the serum vials into a Hewlett-Packard 5890
Series II gas chromatograph equipped with a flame ionization detector. Injector
