Pivovarov et al.: Dissolved Oxyeen. Silicon Phosphorous and Suspended Matter Concentrations
3
OSS Signal
000
02
~ 2
Ice
..s. - 1.5mg/l
.r:. 6
~ 8
"0 10 _ 1.7 mg/l
:0 12
"i 14
~ 16 - 1.8 mgll
18
0 00
~ 2 I-~:<"-~
..s •
.r:. 6
"0 10 - 4.7 m!¥l
9
5
- 1.0 mgll
- 0.6 mgll
- 1.8 mgll
- 0.6 mgll
~ 8 j!.4 mg/1 1
lii '2
OJ 14 _ 3.5 mg/1
9.4 mg/1
~16
\
18 t
SPM (f~d)
I
Turbidity (optical backscatter signal)
STATIONS
10
4
6
11
02
00
02
00
02
00
02
Ice
Ice
I Ice I
Ice
1.6 m!¥l
- 3.0 mgll
- 0.9 m!¥l - 1.3 m!¥l
- 0.5mg/l
- 1.0 mg/l
- 1.0 mgll
- 2.2 mg/l
I
WINTER SITUATION (MAY 18 - 22) ]
12.6 m!¥l
_
3.9 mg/1 I
11 .6 mg/1
- 4.4 m!¥l
_ 2.2 mg/1
BREAKUP SITUATION (JUNE 10-11)
259
o
2
• 6
8
10
12
14
16
18
8
10
12
I.
16
18
Figure 7: In situ optical backscatter record and measured SPM content along the N-S transect (130°30' E).
Stations 3, 9, 5, 10,4, 6 and II show the typical low content in the water column before the spring breakup.
The stations were sampled again between June 10-11. At this time the upper water layer (between approximately
2-\ 0 m water depth) was characterised by high a concentration of SPM and strong optical backscatter signals.
The discrepancy between the summer and winter concentration of silicon is most obvious in
the shallow coastal regions . This is caused by an inflow of silicon-rich freshwater during
winter - when the major source of river water is silicon enriched ground water -, and the
absence of algae which consume dissolved inorganic silicon (Buynevich et a!. , 1980). Because
winter convective mixing is usually not able to destroy the halocline, the distribution of silicon
in the surface water off the delta reflects the input by the Lena river.
In other regions where stratification of the water column breaks down due to high turbulence
(e.g . the polynya), elevated concentrations of silicon may also be caused by the input of
remineralized silicon from bottom sediments.
Oxygen, nutrient and suspended matter distribution during winter (lean-flow)
Before the breakup the oxygen saturation in the Bykovskaya distributary was 56 %. This is in
agreement with earlier winter observations in the Lena (Buynevich et a!., 1980; Cauwet and
Sidorov, 1996) . The comparatively high oxygen saturation distinguishes the Lena river from
other large Siberian rivers. As an example the water in the estuary of the Ob river shows a
complete consumption of oxygen almost every winter (Yudanov, 1929; Rusanov et aI., 1979).
The oxygen distribution under the fast ice cover in the SE Laptev Sea is influenced by the
processes occurring in the polynya region. Intensive mixing in the ice-free polynya results in
the formation of ventilated, cold, dense water. The distribution of oxygen suggests that oxygen
enriched sea water sinks in the polynya region and flows towards the northern Lena delta.
Although, no complete consumption of oxygen was observed in 1996, the possibility of
sporadic occurrences of hydrogen sulphide near the river mouths in regions near the delta was
3
OSS Signal
000
02
~ 2
Ice
..s. - 1.5mg/l
.r:. 6
~ 8
"0 10 _ 1.7 mg/l
:0 12
"i 14
~ 16 - 1.8 mgll
18
0 00
~ 2 I-~:<"-~
..s •
.r:. 6
"0 10 - 4.7 m!¥l
9
5
- 1.0 mgll
- 0.6 mgll
- 1.8 mgll
- 0.6 mgll
~ 8 j!.4 mg/1 1
lii '2
OJ 14 _ 3.5 mg/1
9.4 mg/1
~16
\
18 t
SPM (f~d)
I
Turbidity (optical backscatter signal)
STATIONS
10
4
6
11
02
00
02
00
02
00
02
Ice
Ice
I Ice I
Ice
1.6 m!¥l
- 3.0 mgll
- 0.9 m!¥l - 1.3 m!¥l
- 0.5mg/l
- 1.0 mg/l
- 1.0 mgll
- 2.2 mg/l
I
WINTER SITUATION (MAY 18 - 22) ]
12.6 m!¥l
_
3.9 mg/1 I
11 .6 mg/1
- 4.4 m!¥l
_ 2.2 mg/1
BREAKUP SITUATION (JUNE 10-11)
259
o
2
• 6
8
10
12
14
16
18
8
10
12
I.
16
18
Figure 7: In situ optical backscatter record and measured SPM content along the N-S transect (130°30' E).
Stations 3, 9, 5, 10,4, 6 and II show the typical low content in the water column before the spring breakup.
The stations were sampled again between June 10-11. At this time the upper water layer (between approximately
2-\ 0 m water depth) was characterised by high a concentration of SPM and strong optical backscatter signals.
The discrepancy between the summer and winter concentration of silicon is most obvious in
the shallow coastal regions . This is caused by an inflow of silicon-rich freshwater during
winter - when the major source of river water is silicon enriched ground water -, and the
absence of algae which consume dissolved inorganic silicon (Buynevich et a!. , 1980). Because
winter convective mixing is usually not able to destroy the halocline, the distribution of silicon
in the surface water off the delta reflects the input by the Lena river.
In other regions where stratification of the water column breaks down due to high turbulence
(e.g . the polynya), elevated concentrations of silicon may also be caused by the input of
remineralized silicon from bottom sediments.
Oxygen, nutrient and suspended matter distribution during winter (lean-flow)
Before the breakup the oxygen saturation in the Bykovskaya distributary was 56 %. This is in
agreement with earlier winter observations in the Lena (Buynevich et a!., 1980; Cauwet and
Sidorov, 1996) . The comparatively high oxygen saturation distinguishes the Lena river from
other large Siberian rivers. As an example the water in the estuary of the Ob river shows a
complete consumption of oxygen almost every winter (Yudanov, 1929; Rusanov et aI., 1979).
The oxygen distribution under the fast ice cover in the SE Laptev Sea is influenced by the
processes occurring in the polynya region. Intensive mixing in the ice-free polynya results in
the formation of ventilated, cold, dense water. The distribution of oxygen suggests that oxygen
enriched sea water sinks in the polynya region and flows towards the northern Lena delta.
Although, no complete consumption of oxygen was observed in 1996, the possibility of
sporadic occurrences of hydrogen sulphide near the river mouths in regions near the delta was