|
Newsletter and Technical Publications
<Forum on the Caspian, Aral and Dead Seas-Perspective
of Water Environmental Management and Politics>
<Symposium on the Aral Sea and The Surrounding Region
-Irrigated Agriculture and the Environment>
Limnological Features of Lakes in Central Asia
-Aral Sea and Lake Balkash-
H. Maeda (Lake Biwa Research Institute),
H. Nakahara, Y. Katayama, K. Nishimura,Y. Kawabata (KyotoUniversity),and
T. Kakeda (Kinki University)
Cooperative limnological research between Japan and Kazakhstan has been
carried out in the Aral Sea and Lake Balkhash from 1990. The purpose of this
research is mainly to make clear the mechanisms of response of microorganisms to
the increase of salinity in the Aral Sea and Lake Balkhash following
desertification caused by irrigation..As the first step of the research program,
we obtained the information about characteristic features of water quality in
the lakes.
Introduction
A scientific approach to lake and environment management is concerned with
the study of structures and functions of aquatic ecosystems. The study of
physical, chemical and biological parameters reveals the importance of
structures for understanding the function of the ecosystem. Structures refers to
water quality e.g. the distribution of nutrients (nitrogen and phosphorus) in
the water column and the pattern of phytoplankton and zooplankton connected with
the chemical background. From the functional point of view the primary
production of phytoplankton, metabolically coupled with the supply of limiting
nutrients, is one of the most important key processes of aquatic organisms.
Metabolic activities of micro-organisms are also of eminent importance for
building up definite structures and functions in nature.
The Aral Sea and Lake Balkhash are terminal lakes in arid areas. Therefore,
the tendency is to be affected by environmental change of catchment area rather
than other lakes.
As first step of the research program, we intend to obtain information about
characteristic features of water quality in the lakes. Figures 1 and 2 show the
sampling stations of our observation in the Aral Sea and Lake Balkhash in 1993
and 1994.
.gif)
(larger image)
Figure 1: Sampling Points of Lake Balkhash
.gif)
(larger image)
Figure 2: Samping Points of the Aral Sea
Results and Discussions
Lakes in all regions may be classified based on productivity according to
oligotrophic-eutrophic series. A summary of features contrasting oligotrophic -eutrophic
lakes is displayed in table 1 (after Cole 1983).
Table 1. Features Contrasting Oligotrophic and Eutrophic Lakes-Factors
Contributing to or Resulting from the Two Types (modified from Thienemann,
1925).
|
OlLIGOTROPHY
|
EUTROPHY
|
|
Deep and steep-banked
|
Shallow, broad littoral zone
|
|
Epilimnion volume relatively small compared with hypolimnion
|
Hypolimnion volume relatively small compared with the epilimnion
|
|
High transparency
|
Limited transparency
|
|
Water poor in plant nutrients
|
Plant nutrients are abundant
|
|
Sediments low in organic matter
|
Profundal sediments an organic copropel
|
|
Oxygen always abundant at all levels
|
Oxygen depleted in hypolimnion
during summer
|
|
Littoral plants limited
|
Littoral plants abundant
|
|
Phytoplankton quantitatively poor
|
Abundant phytoplankton
|
|
Water blooms of bluegreen algae lacking
|
Water blooms common
|
|
Profundal bottom fauna diverse;
intolerant of low oxygen tensions
|
Profundal benthos poor in species
which can survive in low oxygen
|
|
Profundal benthos quantitatively poor
|
Profundal benthic biomass great
|
|
Tanytarsus-type midge larvae in profundal benthos; Chaoborus usually
lacking
|
Chironomus, the profundal midge larva; Chaoborus often present
|
Typically, oligotrophic lakes are deep and the hypolimnion is lager than the
epilimnion. Also, eutrophic lakes are often more shallow. The internal loading
of phosphorus from the sediment supplies the euphotic trophogenic zone
continuously with the limiting factor phosphate.
Table 2 shows the comparison of limnological features between Aral Sea, Lake
Balkhash and Lake Biwa. Aral Sea and Lake Balkhash are shallow. Therefore, they
do not fit morphometric oligotrophy.
Table 3 to table 12 give data for water and sediment quality of the Aral Sea
and Lake Balkhash. These data show that the Aral Sea and Lake Balkhash have an
oligotrophic level because of low nutrients of water and sediment.
Table 2. Comparison of limnological features between Aral Sea, Lake
Balkhash and Lake Biwa
| |
Aral Sea |
Lake Balkhash |
Lake Biwa |
Place / latitude |
46°10' |
45°70',46 80' |
35° 14' |
Altitude / m |
53*
|
342*
|
85*
|
| Surface area / km2 |
6646*
|
1843*
|
672.4*
|
|
Volume / km3
|
|
|
27.5*
|
|
Maximum depth / m
|
68*
|
26*
|
103.8*
|
|
Average of depth / m
|
|
|
41*
|
|
Residence time / year
|
|
|
5.5
|
|
Mean water temperature /°C
|
|
|
14.1
|
|
Transparency / m
|
1.0
|
0.5
|
4.3
|
|
pH
|
8.19-8.61
|
8.4-9.3
|
7.0-9.0
|
|
NH4-N / ppm
|
0.011-0.209
|
0.023-1.462
|
0.0562-0.03
|
|
T-P / ppm
|
0.001-0.018
|
0.011-0.072
|
0.0009-0.0197
|
|
Fish catch / ton
|
|
|
4919
|
|
Population density per lake volume / population 10-6
m-3
|
|
|
41
|
|
Occurrence of algal bloom
|
|
|
Microcystis, Uroglen
|
|
A condition of nutrient
|
|
|
middle nutrient
|
* Data of 1988
Table 3. Water Quality of Lake Balkhash
|
Station
|
Sampling depth (m)
|
Water depth (m)
|
Trans- parency (m)
|
Temp.
(°C)
|
pH
|
Cond. (mS/cm)
|
Salinity
|
DO
|
ST.1 A
|
0
|
0.3
|
0.3<
|
19.1
|
8.8
|
3.4
|
0.2
|
9.5
|
|
ST.1 B
|
0
|
___
|
___
|
19.7
|
8.7
|
3.4
|
0.2
|
8.3
|
|
ST.2
|
0
|
1.8
|
0.40
|
20.4
|
8.4
|
3.4
|
0.2
|
8.2
|
| |
1.5
|
1.8
|
0.40
|
20.4
|
8.4
|
3.4
|
0.2
|
5.7
|
|
ST.3
|
0
|
1.7
|
0.25
|
21.2
|
8.8
|
2.6
|
___
|
8.5
|
|
|
1.5
|
1.7
|
0.25
|
21.2
|
8.8
|
2.6
|
0.1
|
7.7
|
|
ST.4
|
0
|
5.5
|
0.25
|
21.9
|
8.8
|
2.1
|
0.1
|
8.6
|
| |
5
|
5.5
|
0.25
|
21.9
|
8.8
|
2.1
|
0.1
|
6.8
|
|
ST.5
|
0
|
5.8
|
0.25
|
21.7
|
8.8
|
1.9
|
0.1
|
8.5
|
| |
5.5
|
5.8
|
0.25
|
21.8
|
8.8
|
1.9
|
0.1
|
6.5
|
|
ST.6
|
0
|
3.9
|
0.30
|
22.0
|
8.8
|
1.9
|
0.1
|
8.4
|
| |
3.5
|
3.9
|
0.30
|
21.9
|
8.8
|
1.9
|
0.1
|
7.2
|
|
ST.7
|
0
|
5.8
|
0.30
|
22.6
|
8.8
|
2.0
|
0.1
|
8.8
|
| |
5.5
|
5.8
|
0.30
|
22.3
|
8.8
|
2.0
|
0.1
|
7.0
|
|
ST.8 A
|
0
|
0.4
|
0.4<
|
21.7
|
9.1
|
3.6
|
0.2
|
7.4
|
|
ST.8 B
|
0
|
___
|
___
|
22.0
|
9.3
|
3.6
|
0.2
|
7.7
|
|
ST.9
|
0
|
1.7
|
0.50
|
21.4
|
9.0
|
4.1
|
0.2
|
5.8
|
| |
1.5
|
1.7
|
0.50
|
21.5
|
9.0
|
4.1
|
0.2
|
6.4
|
|
ST.10
|
0
|
7
|
0.70
|
23.7
|
9.0
|
3.6
|
0.2
|
8.5
|
| |
6.5
|
7
|
0.70
|
21.7
|
9.0
|
3.5
|
0.2
|
7.5
|
|
ST.11
|
0
|
7
|
0.45
|
23.1
|
9.0
|
5.0
|
0.3
|
7.9
|
|
ST.12
|
0
|
13.6
|
1.50
|
22.2
|
9.0
|
5.0
|
0.3
|
8.2
|
| |
5
|
13.6
|
1.50
|
21.8
|
9.0
|
5.0
|
0.3
|
6.7
|
| |
13
|
13.6
|
1.50
|
21.9
|
9.0
|
5.0
|
0.3
|
5.9
|
|
ST.13
|
0
|
3
|
0.45
|
22.9
|
9.0
|
4.8
|
0.3
|
8.5
|
| |
2.5
|
3
|
0.45
|
22.6
|
9.0
|
4.8
|
0.3
|
7.4
|
|
ST.14
|
0
|
7.1
|
0.50
|
23.0
|
9.0
|
4.6
|
0.2
|
8.4
|
| |
6.5
|
7.1
|
0.50
|
22.8
|
9.0
|
4.7
|
0.2
|
6.8
|
|
ST.15
|
0
|
4
|
0.50
|
23.6
|
9.0
|
3.7
|
0.2
|
8.7
|
| |
3.5
|
4
|
0.50
|
2.19
|
9.0
|
4.0
|
0.2
|
7.7
|
|
The north basin of Lake Biwa
|
0
|
30
|
5-10
|
24.3
|
9.1
|
0.1
|
|
10.3
|
Table 4. Concentration of Nutrients of Lake Balkhash
Station
|
NH4- N
|
NO2-N, NO3-N
|
SiO2- Si
|
PO4-P
|
T-N
|
T-P
|
TON
|
TOP
|
ST.1 A
|
0.030
|
0.016
|
5.6
|
0.002
|
0.563
|
0.043
|
0.518
|
0.042
|
|
ST.1 B
|
0.632
|
0.018
|
5.9
|
0.002
|
0.839
|
0.044
|
0.190
|
0.042
|
|
ST.2 0m
|
0.016
|
0.014
|
7.1
|
0.001
|
0.362
|
0.040
|
0.331
|
0.039
|
ST.3 0m
|
0.025
|
0.019
|
6.6
|
0.001
|
0.346
|
0.034
|
0.303
|
0.033
|
ST.4 0m
|
0.020
|
0.010
|
6.0
|
0.000
|
0.333
|
0.042
|
0.304
|
0.042
|
ST.4 5m
|
0.049
|
0.013
|
6.0
|
0.001
|
0.300
|
0.044
|
0.237
|
0.043
|
ST.5 0m
|
0.141
|
0.022
|
5.7
|
0.006
|
0.359
|
0.072
|
0.196
|
0.066
|
ST.5 5.5m
|
0.019
|
0.017
|
5.9
|
0.005
|
0.295
|
0.054
|
0.259
|
0.050
|
ST.6 0m
|
0.023
|
0.027
|
5.9
|
0.002
|
0.271
|
0.048
|
0.220
|
0.046
|
ST.6 3.5m
|
0.060
|
0.014
|
6.0
|
0.002
|
0.274
|
0.048
|
0.200
|
0.046
|
ST.7 0m
|
0.046
|
0.040
|
6.1
|
0.001
|
0.327
|
0.044
|
0.240
|
0.043
|
ST.7 5.5m
|
0.078
|
0.021
|
6.2
|
0.001
|
0.862
|
0.011
|
0.763
|
0.010
|
ST.8 A
|
0.054
|
0.007
|
4.2
|
0.001
|
0.495
|
0.038
|
0.434
|
0.037
|
ST.8 B
|
0.815
|
0.012
|
3.8
|
0.002
|
3.915
|
0.018
|
3.088
|
0.016
|
ST.9 0m
|
1.036
|
0.018
|
7.2
|
0.002
|
0.441
|
0.017
|
___
|
0.015
|
ST.9 1.5m
|
0.038
|
0.016
|
7.2
|
0.001
|
0.819
|
0.028
|
0.765
|
0.027
|
ST.10 0m
|
0.363
|
0.010
|
7.2
|
0.002
|
0.475
|
0.031
|
0.103
|
0.029
|
ST.10 6.5m
|
0.194
|
0.017
|
7.3
|
0.002
|
3.269
|
0.044
|
3.058
|
0.045
|
ST.11 0m
|
0.201
|
0.016
|
6.5
|
0.001
|
0.478
|
0.041
|
0.261
|
0.040
|
ST.12 0m
|
0.713
|
0.009
|
7.2
|
0.002
|
0.489
|
0.017
|
___
|
0.016
|
ST.12 5m
|
1.080
|
0.015
|
7.5
|
0.002
|
0.496
|
0.036
|
___
|
0.034
|
ST.12 13m
|
0.073
|
0.014
|
7.0
|
0.002
|
0.506
|
0.044
|
0.419
|
0.042
|
ST.13 0m
|
0.060
|
0.013
|
7.1
|
0.002
|
0.637
|
0.046
|
0.564
|
0.044
|
ST.13 2.5m
|
0.028
|
0.007
|
7.1
|
0.002
|
1.357
|
0.038
|
1.340
|
0.036
|
ST.14 0m
|
0.536
|
0.023
|
6.5
|
0.002
|
1.098
|
0.042
|
0.539
|
0.041
|
ST.14 6.5m
|
0.092
|
0.010
|
6.8
|
0.002
|
1.011
|
0.040
|
0.909
|
0.038
|
ST.15 0m
|
0.761
|
0.009
|
7.1
|
0.001
|
0.094
|
0.038
|
___
|
0.037
|
ST.15 2.5m
|
1.462
|
0.008
|
7.4
|
0.001
|
0.709
|
0.023
|
___
|
0.022
|
| |
|
|
|
|
|
|
|
|
|
The north basin of Lake Biwa
|
0.022
|
0.016
|
0.6
|
0.007
|
0.153
|
0.030
|
0.137
|
0.023
|
|
The south basin of Lake Biwa
|
0.023
|
0.006
|
0.9
|
0.010
|
0.175
|
0.040
|
0.169
|
0.030
|
Table 5. Chl-a Concentration of Lake Balkhash
|
Station
|
Chl-a GF-D
|
Chl-a GF-D
|
b-Carotin GF-D
|
Station
|
Chl-a GF-D
|
Chl-a
GF-F
|
b-Carotin GF-D
|
|
ST.1 A
|
3.99
|
4.15
|
____
|
ST.10 0m
|
6.21
|
7.06
|
0.68
|
|
ST.1 B
|
5.45
|
____
|
0.43
|
ST.10 6.5m
|
3.80
|
6.25
|
____
|
|
ST.2
|
7.80
|
____
|
0.88
|
ST.11
|
5.62
|
4.85
|
0.36
|
|
ST.3
|
11.08
|
____
|
0.55
|
ST.12 0m
|
4.77
|
7.66
|
____
|
|
ST.4
|
9.83
|
13.69
|
____
|
ST.12 5m
|
2.75
|
2.42
|
____
|
|
ST.5
|
10.57
|
9.52
|
____
|
ST.12 13m
|
6.80
|
7.86
|
____
|
|
ST.6
|
7.37
|
7.19
|
____
|
ST.13
|
6.11
|
7.95
|
0.43
|
|
ST.7
|
8.04
|
11.23
|
0.34
|
ST.14
|
4.17
|
6.33
|
0.34
|
|
ST.8 A
|
4.76
|
____
|
0.46
|
ST.15
|
5.01
|
____
|
____
|
|
ST.8 B
|
7.78
|
6.12
|
____
|
|
|
|
|
|
ST.9
|
7.56
|
____
|
1.10
|
The north basin of Lake Biwa
|
8.12
|
1.20
|
|
(µg/l)
Table 6. Amount of Microorganisms of Lake Balkhash
|
Station
|
Pico
plankton
|
Bacteria
|
Station
|
Pico plankton
|
Bacteria
|
|
ST.1 A
|
1.2 x 105
|
1.5 x 106
|
ST.9
|
1.3 x 105
|
2.2 x 106
|
ST.1 B
|
1.5 x 105
|
1.3 x 106
|
ST.10
|
9.2 x 104
|
1.0 x 106
|
|
ST.2
|
9.0 x 104
|
1.1 x 106
|
ST.11
|
9.8 x 104
|
1.8 x 106
|
|
ST.3
|
1.6 x 105
|
1.1 x 106
|
ST.12 0m
|
9.7 x 104
|
1.5 x 106
|
|
ST.4
|
8.8 x 103
|
1.3 x 106
|
ST.12 13m
|
1.1 x 105
|
1.3 x 106
|
|
ST.5
|
1.7 x 105
|
1.2 x 106
|
ST.13
|
7.9 x 104
|
1.6 x 106
|
|
ST.6
|
1.3 x 105
|
1.1 x 106
|
ST.14
|
1.2 x105
|
1.9 x 106
|
|
ST.7
|
1.1 x 105
|
1.3 x 106
|
ST.15
|
7.8 x 104
|
1.7 x 106
|
|
ST.8 A
|
1.4 x 105
|
1.5 x 106
|
|
|
|
|
ST.8 B
|
1.7 x 105
|
1.6 x 106
|
The north basin of Lake Biwa
|
6.6 x 105
|
5.9 x 106
|
|
|
|
|
The north basin of Lake Biwa
|
4.0 x 105
|
6.3 x 106
|
(cells/ml)
Table 7. Carbon and Nitrogen content of sediment in Lake
Balkhash
Station
|
|
C (%)
|
N (%)
|
C : N
|
Station
|
|
C (%)
|
N (%)
|
C : N
|
ST.A
|
upper
|
0.20
|
0.03
|
6.7
|
ST.9
|
0-1 cm
|
0.07
|
0.01
|
7.0
|
|
|
lower
|
0.13
|
0.02
|
6.5
|
|
2-3 cm
|
0.13
|
0.01
|
13.0
|
ST.2
|
upper
|
0.16
|
0.03
|
5.3
|
|
5-6 cm
|
0.06
|
0.01
|
6.0
|
|
|
lower
|
0.09
|
0.01
|
9.0
|
ST.10
|
0-1 cm
|
0.78
|
0.07
|
11.1
|
ST.3
|
upper
|
0.09
|
0.02
|
4.5
|
|
2-3 cm
|
0.53
|
0.06
|
8.8
|
|
|
lower
|
0.21
|
0.04
|
5.3
|
|
5-6 cm
|
0.65
|
0.06
|
10.8
|
ST.4
|
upper
|
0.11
|
0.02
|
5.5
|
|
9-10 cm
|
0.45
|
0.06
|
7.5
|
|
|
lower
|
0.28
|
0.04
|
7.0
|
ST.12
|
0-1 cm
|
1.25
|
0.13
|
9.6
|
|
ST.5
|
0-1 cm
|
0.67
|
0.13
|
5.2
|
|
2-3 cm
|
1.11
|
0.09
|
12.3
|
|
|
2-3 cm
|
0.68
|
0.10
|
6.8
|
|
5-6 cm
|
2.90
|
0.22
|
13.2
|
|
|
5-6 cm
|
0.56
|
0.10
|
5.6
|
ST.13
|
0-1 cm
|
0.37
|
0.05
|
7.4
|
|
|
9-10 cm
|
0.57
|
0.10
|
5.7
|
|
2-3 cm
|
0.46
|
0.05
|
9.2
|
ST.6
|
0-1 cm
|
0.74
|
0.13
|
5.7
|
ST.14
|
0-1 cm
|
0.51
|
0.07
|
7.3
|
|
|
2-3 cm
|
0.69
|
0.10
|
6.9
|
|
2-3 cm
|
0.50
|
0.06
|
8.3
|
|
|
5-6 cm
|
0.61
|
0.10
|
6.1
|
|
5-6 cm
|
0.47
|
0.06
|
7.8
|
|
|
9-10 cm
|
0.66
|
0.12
|
5.5
|
|
9-10 cm
|
0.46
|
0.06
|
7.7
|
ST.8A
|
0-1 cm
|
0.09
|
0.02
|
4.5
|
ST.15
|
0-1 cm
|
0.39
|
0.05
|
7.8
|
|
|
2-3 cm
|
0.05
|
0.02
|
2.5
|
|
2-3 cm
|
0.44
|
0.06
|
7.3
|
|
|
5-6 cm
9-10 cm
|
0.12
0.17
|
0.01
0.00
|
12.0
|
The south basin of Lake Biwa
|
0-1 cm
|
1.81
|
0.19
|
9.53
|
|
|
|
|
|
|
|
2-3 cm
|
2.2
|
0.24
|
9.25
|
|
|
|
|
|
|
|
5-6 cm
|
2.53
|
0.27
|
9.37
|
|
|
|
|
|
|
|
9-10 cm
|
2.67
|
0.30
|
8.90
|
Table 8. Water Quality of Aral Sea
|
Station
|
Water depth (m)
|
Sampling depth (m)
|
Temp.
(°C)
|
pH
|
Cond.
|
Do
|
Salinity
|
Turb.
|
|
AR-8
|
0.9
|
0.0
|
17.1
|
8.61
|
44.1
|
9.61
|
28.7
|
3
|
|
AR-17
|
0.8
|
0.0
|
17.2
|
8.19
|
1.6
|
7.83
|
0.7
|
295
|
AR-18
|
1.0
|
0.0
|
14.4
|
8.46
|
29.7
|
8.89
|
18.1
|
7
|
AR-19
|
1.0
|
0.0
|
16.7
|
8.45
|
15.4
|
7.8
|
9.1
|
34
|
AR-20 surface
|
2.8
|
0.0
|
17.4
|
8.45
|
29.4
|
7.3
|
18.4
|
21
|
AR-20 bottom
|
|
2.8
|
15.8
|
___
|
___
|
8
|
___
|
___
|
AR-21
|
2.0
|
0.0
|
20.7
|
8.50
|
13.0
|
8.9
|
7.6
|
187
|
AR-22
|
2.0
|
0.0
|
21.1
|
8.35
|
2.3
|
7.8
|
1.1
|
10
|
Table 9. Concentration of Nutrients of Aral Sea
Station
|
NH4-N
|
NO2-N, NO3-N
|
SiO2-Si
|
PO4-P
|
T-N
|
T-P
|
TON
|
TOP
|
|
AR-8
|
0.209
|
0.017
|
0.02
|
0.002
|
0.8531
|
0.0033
|
0.626
|
0.001
|
|
AR-17
|
0.002
|
0.052
|
5.36
|
0.001
|
0.3264
|
0.0019
|
0.273
|
0.001
|
AR-18
|
0.056
|
0.025
|
1.32
|
0.002
|
0.711
|
0.0068
|
0.630
|
0.005
|
AR-19
|
0.058
|
0.085
|
3.28
|
0.001
|
0.6479
|
0.0063
|
0.505
|
0.005
|
AR-20 surface
|
0.095
|
0.044
|
1.55
|
0.002
|
0.8356
|
0.0087
|
0.697
|
0.007
|
AR-20 bottom
|
0.087
|
0.004
|
0.14
|
0.002
|
0.7866
|
0.0181
|
0.696
|
0.016
|
AR-21
|
0.026
|
0.062
|
3.65
|
0.001
|
0.5555
|
0.0067
|
0.467
|
0.006
|
AR-22
|
0.011
|
0.003
|
4.41
|
0.001
|
0.3874
|
0.0035
|
0.374
|
0.002
|
|
|
|
|
|
|
|
|
|
|
| The
north basin of Lake Biwa |
0.022
|
0.016
|
0.6
|
0.007
|
0.153
|
0.030
|
0.137
|
0.023
|
| The
south basin of Lake Biwa |
0.023
|
0.006
|
0.9
|
0.010
|
0.175
|
0.040
|
0.169
|
0.030
|
Table 10. Chl-a Concentration of Aral Sea
Station
|
Chl-a GF-D
|
Chl-a GF-F
|
Station
|
Chl-a GF-D
|
Chl-a GF-F
|
|
AR-8
|
0.21
|
0.09
|
AR-20 bottom
|
0.21
|
0.07
|
|
AR-17
|
0.51
|
0.15
|
AR-21
|
0.22
|
0.20
|
|
AR-18
|
0.34
|
0.09
|
AR-22
|
0.20
|
0.17
|
|
AR-19
|
0.34
|
0.19
|
|
|
|
|
AR-20 surface
|
0.30
|
0.08
|
The north basin of Lake Biwa
|
8.12
|
1.20
|
(µg/l)
Table 11. Amount of Microorganisms of Aral Sea
|
Station
|
Pico plankton
|
Bacteria
|
Station
|
Pico
plankton
|
Bacteria
|
AR-8
|
1.0 x 105
|
1.6 x 105
|
AR-21
|
6.1 x 104
|
3.3 x 105
|
AR-17
|
3.6 x 104
|
2.5 x 105
|
AR-22
|
9.0 x 104
|
2.2 x 105
|
AR-18
|
5.7 x 104
|
1.5 x 105
|
|
|
|
AR-19
|
3.3 x 104
|
|
|
|
|
AR-20 surface
AR-20 bottom
|
7.5 x 104
1.3 x 105
|
3.2 x 106
1.4 x 106
|
The north basin of Lake Biwa
|
6.6 x 105
|
5.9 x 106
|
|
|
|
|
The south basin of Lake Biwa
|
4.0 x 105
|
6.3 x 106
|
(cells/ml)
Table 12. Carbon and Nitrogen Content of Sediment in Aral
Sea
Station
|
|
C (%)
|
N (%)
|
C:N
|
Station
|
|
C (%)
|
N (%)
|
C:N
|
|
AR8
|
0-1 cm
|
0.53
|
0.03
|
17.67
|
AR19
|
0-1 cm
|
1.94
|
0.07
|
27.71
|
|
|
2-3 cm
|
0.12
|
0.02
|
6.00
|
|
2-3 cm
|
2.04
|
0.08
|
25.50
|
|
|
5-6 cm
|
0.17
|
0.00
|
|
|
5-6 cm
|
1.85
|
0.11
|
16.82
|
|
|
9-10 cm
|
0.13
|
0.02
|
6.50
|
|
9-10 cm
|
0.91
|
0.04
|
22.75
|
AR17
|
0-1 cm
|
0.45
|
0.02
|
22.50
|
AR20
|
0-1 cm
|
1.12
|
0.11
|
10.18
|
|
|
2-3 cm
|
1.89
|
0.06
|
31.50
|
|
2-3 cm
|
0.86
|
0.05
|
17.20
|
|
|
5-6 cm
|
1.82
|
0.05
|
11.30
|
|
5-6 cm
|
0.48
|
0.05
|
9.60
|
|
|
9-10 cm
|
2.02
|
0.05
|
36.40
|
|
9-10 cm
|
0.95
|
0.06
|
15.83
|
|
AR18
|
0-1 cm
|
3.56
|
0.09
|
39.56
|
The south basin of LakeBiwa
|
0-1 cm
|
1.18
|
0.19
|
9.53
|
|
|
2-3 cm
5-6 cm
|
2.99
3.18
|
0.14
0.14
|
21.36
22.71
|
|
2-3 cm
|
2.22
|
0.24
|
9.25
|
|
|
9-10 cm
|
3.78
|
0.06
|
63.00
|
|
5-6 cm
|
2.53
|
0.27
|
9.37
|
|
|
|
|
|
|
|
9-10 cm
|
2.67
|
0.30
|
8.90
|
In general, the climate influences markedly the balance
between precipitation and evaporation and thereby the salinity.
In arid areas where closed basins hold concentrated waters, the salinity is
governed by inputs of dissolved ions from the catchment area and the degree of
evaporation. Other factors of importance for salinity are temperature and wind.
Weathering of rocks which may have a big influence on the composition of
electrolytes in lake water, is accelerated by
a warm climate. Wind influences the chemical composition of precipitation and
sites of deposition. Saline lakes can be classified on the basis of dominating
anions into carbonate, chloride or sulfate waters. Aral Sea is a carbonate type
and characterized by NaHCO3 and Na2CO3, termed alkali
waters because of the high pH. The range of salinity is extremely high, up to
28,700mg/l in Aral Sea (St. AR-8).
References:
Ohl, W., 1982. Faehrstoffzufuhren des Grebiner Sees
durch atmosphaerische Niederschlaege und Oberflaechenabschwemmung des
Einzugsgebietes. (Nutrient supply of Lake Grebiner by atmospheric precipitation
and surface run-off from the watershed area). Arch. Hydrobiol. 95; 331-363.
Thienemann, A., 1925. Die Binnengewasser Mitteleuropas.
Eine limnologische Einfurung. - die Binnengewasser 1: 1-255.
Thienemann, A., 1927. Der Bau des Seebeckens in seiner
Bedeutung fur den Ablauf des Lebens im See. - Verh. Zool. -Bot. Ges. Wien 77:
87-91.
|
Table
of Contents
