International Journal of Marine Science, 2017, Vol.7, No.16, 141-160
146
Continued Table 5
Parameters
Seasons
Karnafullly
Min.
Max.
BOD
Pre-monsoon
0.22
9.17
Monsoon
0.21
6.22
Post-monsoon
11.39
122.46
Nitrite-N
Pre-monsoon
1.01
3.89
Monsoon
.00
5.18
Post-monsoon
1.60
14.60
Phosphate-P
Pre-monsoon
2.00
3.37
Monsoon
0.12
4.94
Post-monsoon
9.26
212.81
Sulphate-S
Pre-monsoon
152.08
974.10
Monsoon
28.55
977.08
Post-monsoon
9.26
32.87
Fe
Pre-monsoon
0.06
2.30
Monsoon
0.40
2.72
Post-monsoon
0.23
3.24
Mn
Pre-monsoon
0.01
0.92
Monsoon
0.22
0.45
Post-monsoon
0.01
0.24
Note: Source:
Ahmed
(2010)
2.2 Sediment
The overlying deposits of the Karnafully river is consist of successive layers of mud and sand (Rizvi, 1971).
During rainy season, a large amount of sand and mud particles run down into the river water increasing turbidity
and decreasing navigability of the river by siltation (Hossain, 1992).
Chowdhury (2005) conductd a
comprehensive study on the soil of
the Karnafully river (Table 6).
Table 6 Organic carbon, organic matter and soil texture of sediment at three stations during post-monsoon (January, 2005)
Parameters
Amanat Shah Bridge
Sadar Ghat
Jetty no. 15
Organic carbon
0.200
0.230
0.430
Organic matter
0.344
0.396
0.740
Soil texture Sand (%)
82.36
84.25
78.87
Silt (%)
7.82
6.90
11.52
Clay (%)
9.82
8.85
9.61
Note: Source: Chowdhury (2005)
2.3 Macro benthos
Macro benthos distribution vary spatially and temporally (Sharif et al., 2017). According to Chowdhury (2005)
maximum population density 148583 indiv/m
2
was recorded during pre-monsoon at Amanat Shah Bridge and
minimum population density 1333.33 indiv/m
2
was recorded at Jetty no.15 during monsoon. Sharif et al. (2017)
recorded 25 major taxa of zooplankton from the Karnafully River of which 23 taxa during monsoon, 20 taxa
during post monsoon and 20 taxa during pre-monsoon. Species richness, diversity and evenness were very low in
the mouth of the Chaktai canal where majority of sewage materials of Chittagong city falls into the Karnafully
estuary in comparison with the Goverment Fish landing station and Eastern side of the third Karnafully Bridge
(Molla et al., 2014). Oligochaetes, the most common that constitute the largest assembles of benthic form during
pre-monsoon and lowest during monsoon (Kamruzzaman, 2003) (Table 7).
2.4 Bacteria
Health hazard bacteria are
Escherichia coli
, Fecal
Streptococci
sp. and
Staphylococcus.
Occurrence of
Salmonella
sp. and
Vibrio cholerae
were also found (Alam, 2005). In compare with bacterial load between water and sediment,
