Environmental Engineering Reference
In-Depth Information
Figure 2.
Vertical distribution of sulfate, hydrogen sulfide, and methane in Ace Lake (Decem-
ber 1987) (data from [18]). The position of the oxic/anoxic interface (OAI) was found to be at
11.7 m during our field work in November 2000 whereas the OAI was at 12.0 m in December
1987.
face) in the water column were: oxic mixolimnion (1.7
−
2.2 m; 6.7
−
7.2 m;
10.2
10.7 m), anoxic and sulfidic chemocline with dense accumulation of
anoxygenic photosynthetic GSB (11.7
−
−
12.2 m), anoxic and sulfidic moni-
−
−
−
molimnion (14.7
22.0 m). In order to collect par-
ticulate organic matter (POM) from the water samples, a volume of 0.25
15.2 m; 18.2
18.7 m; 21.5
−
15 L,
depending on particle densities, was filtered through 0.7 µm pore-size glass fi-
bre filters (GFF) (Millipore). The particle density was highest in the chemocline
and in the monimolimnion. The filtrate was then filtered through 0.2 µm pore-
size polycarbonate (PC) filters (Millipore) in order to collect small prokaryotic
cells that were not collected during the first filtration step. The filters were
stored at -40
◦
C prior to DNA or lipid extraction. The extracts from both the
GFF and PC filters of each water depth were pooled.
Using a gravity corer, a 150-cm-long sediment core with a diameter of 5 cm
was obtained from the depocentre (25 m; 68.47209
◦
S, 78.18732
◦
E) of Ace
Lake. Immediately after sampling, the sediment core was kept in the dark and
stored in the dark at -20
◦
C at Davis Station and in the dark at -40
◦
C at the
Royal NIOZ. At the Royal NIOZ, the frozen sediment core was sliced in 2 cm
