International Journal of Marine Science, 2017, Vol.7, No.12, 102-113
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Table 1 Physico-chemical parameters of surface water in the study area
Parameters/ Stations
Sandwip
Hatiya
Bhola
Barisal
Chandpur
M PM M PM M PM M PM M PM
Air temperature (°C)
33
28
27.2 29
25.5 23
32
28
26
25
Water Temperature
(°C)
31
23
28
22.5 28.5 21
29
22
29
21
Salinity (‰)
1
15
0
10
0
0
0
0
0
0
Secchi Depth (cm)
4
35
7
45
12
65
12
37
55
60
TSS (mg/L)
10.8275 1.2922 7.688 1.3377 3.6595 1.3007 5.4435 1.3267 0.3175 1.3332
TOM (mg/L)
0.856
0.6396 0.7955 0.6116 0.774 0.5361 0.79 0.5876 0.4835 0.5636
pH
6.4
7
6.4
7
6.8
6.5
7
6.6
7
6.5
DO (ml/L)
3.7
1.9
3.9
2
5.2
2.5
5.5
2.7
5.5
2.8
BOD ml/ L
17
0
21
2
38
13
35
6
34
7
CO2 (ml/L)
0.396
0.34
0.396 0.4
0.594 0.5
0.99 0.3
0.99 0.3
Alkalinity (mg/L)
2.1
1.05
1.5
1
1.8
1.05 0.7
1.1
ND 0.95
Hˉ CO3 (mg/L)
0.000244 0.000244 0.0004 0.0002 0.0004 0.0004 0.0002 0.0003 0.0001 0.0004
Note: M= Monsoon; PM= Post-monsoon; ND = Not detected
Table 2 Physico-chemical parameters of sub-surface water (at 3 m depth) in the study area
Parameters/ Station
Sandwip
Hatiya
Bhola
Barisal
Chandpur
M PM M PM M PM M PM M PM
Water Temperature (°C) 29
22
28
22
28.5 21
29
22
29.5
21
Salinity (‰)
1
15
0
8
0
0
0
0
0
0
TSS (mg/L)
10.08 1.4597 7.3085 1.3307 6.617 1.2727 8.9995 1.3897 0.671 1.3507
TOM (mg/L)
0.797 0.9106 0.775 0.9386 0.8165 0.5181 0.784 0.6486 0.8125 0.5838
pH
6.5
7.2
6.7
6.9
7.1
7
7.2
6.8
7
7
DO (ml/L)
4.8
2.1
6
2.5
4
2.04
4.4
2.7
4.5
2.7
BOD (ml/L)
23
1
41
12
27
2.4
25
9
32
4
CO2 (ml/L)
0.396 2.4
0.396 0.6
0.594 0.3
0.386 0.2
0.99
0.3
Alkalinity (mg/L)
1.4
0.95
1.7
1
1.9
1.1
1.2
1.15 ND 0.5
Hˉ CO3 (mg/L)
0.0001 0.00030 0.00012 0.00036 0.00012 0.00024 0.00024 0.00030 0.00012 0.00024
Note: M= Monsoon; PM= Post-monsoon; ND = Not detected
1.4 Bottom sediment analysis
The collected sediment samples for analysis were kept in labeled poly-bags. The
in situ
sediment pH was
determined by a Soil pH tester (Takemura Electric Works Ltd. Japan), soil
in situ
temperature was recorded (by
using a graduated Centigrade thermometer) immediately. Then samples weight (using spring balance) were
recorded on board the vessel and were transferred to the laboratory for analysis. In the laboratory the samples
were mixed thoroughly to prepare a composite sample and were dried at room temperature. The dry soil samples
were sieved at 2 mm mesh. The sieved samples were dried again in an oven at 105°C for 12 hours. The soil
extract water pH was determined by a pH meter. The soil composition (percentage of sand, silt and clay) were
determined (Boyd and Tucker, 1992). Finally the soil texture were calculated.
1.5 Benthos samples analysis
The bottom sediment were collected for macrobenthos study using same Petersen Grab sampler and were sieved
using 0.5 mm mesh. The sieved samples were preserved in a labeled plastic container with 70% alcohol (APHA,
1974) and transferred to laboratory for study. In the laboratory, Bengal Rose was added to samples (APHA, 1975)
and left overnight for proper staining to facilitate benthos sorting. The sorted organisms were stored in vials with
70% ethanol for further study and identified as well as for photographs. The benthos were identified following
Alam (1993); Ahmed (1990); Harkanta and Parulekar (1994); Jegadeesan and Ayyakkkannu (1991); Chandran et
