International Journal of Marine Science, 2017, Vol.7, No.16, 141-160
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3.4.5 Heavy metal pollution
Heavy metal concentrations in the water of the river varied temporally and spatially (Bhuyan and Islam, 2017).
Heavy metal concentration varied according to seasons in water, sediment and fish (Table 16; Table 17).
Table 16 Seasonal variation of trace metal concentrations (μg/mL) in water sample of the Karnafully River Estuary
Station
Area
Season
Metal concentration (μg/mL)
Cr
Mn
Zn
Ni
Cu
Pb
Cd
Fe
1
Mouth
Premonsoon
0.573
1.174 0.541
0.493
0.390 0.563
0.139 26.316
Monsoon
0.602
1.210 0.781
0.520
0.612 0.616
0.217 35.129
Postmonsoon
0.421
0.686 0.625
0.356
0.391 0.405
0.119 20.025
2
Naval base
Premonsoon
0.741
0.662 0.682
0.516
0.372 0.542
0.093 25.012
Monsoon
0.687
0.742 0.970
0.619
0.674 0.698
0.211 40.252
Postmonsoon
0.429
0.498 0.472
0.510
0.449 0.437
0.129 23.168
3
Sadarghat
Premonsoon
0.572
1.121 0.932
0.697
0.543 0.916
0.192 31.021
Monsoon
0.925
1.173 1.186
0.865
0.918 1.195
0.210 42.203
Postmonsoon
0.721
0.972 0.852
0.811
0.903 0.876
0.185 22.193
4
Kalurghat
Premonsoon
0.809
1.071 0.731
0.685
0.711
0.772
0.159 35.325
Monsoon
0.851
1.372 0.910
0.759
0.973 0.747
0.182 36.421
Postmonsoon
0.512
0.983 1.112
0.664
0.891 0.675
0.090 28.120
Note: Source: Sarkar (1998)
Table 17 Seasonal variation of trace metal concentrations (μg/mL) in sediment sample of the Karnafully River Estuary
Station
Area
Season
Metal concentration (μg/mL)
Cr
Mn
Zn
Ni
Cu
Pb
Cd
Fe
1
Mouth
Premonsoon
65.852 60.403 31.191 28.206 34.813 40.165 0.761 3230.69
Monsoon
67.071 64.231 29.075 32.157 32.129 38.982 0.984 3425.49
Postmonsoon
64.462 55.012 28.543 26.021 9.615
27.065 0.519 2910.52
2
Naval base
Premonsoon
56.952 62.743 38.019 56.031 35.025 35.593 1.552 3117.71
Monsoon
57.021 59.131 36.051 58.179 50.741 37.794 1.101 3009.79
Postmonsoon
53.148 56.189 16.724 49.256 10.059 25.110 0.813 3349.29
3
Sadarghat
Premonsoon
70.105 72.152 38.174 55.052 28.561 39.665 1.001 3649.01
Monsoon
71.243 70.210 40.051 62.916 49.718 33.891 0.803 3810.15
Postmonsoon
68.183 68.421 29.215 59.421 17.252 30.571 0.795 3239.14
4
Kalurghat
Premonsoon
69.631 65.321 37.145 46.021 22.192 39.158 0.625 3323.65
Monsoon
67.542 68.145 40.253 39.365 37.681 40.081 0.712 3467.05
Postmonsoon
63.748 61.021 38.121 44.101 24.056 34.269 0.306 3126.42
Note: Source: Sarkar (1998)
Most of the dissolved heavy metals were found to be in slightly higher concentrations during winter than that of
the rainy season. This trend indicates that during low flow condition of river, the accumulation of the metal
concentration increases (Dey et al., 2015) (Table 18).
Table 18 Seasonal variation of trace metal concentrations (μg/mL) in Jew fish (
Otolithoides microdon
) sample of the Karnafully
River Estuary (Sarkar, 1998)
Representative organs
Season
Metal concentration (μg/mL)
Cr
Mn
Zn
Ni
Cu
Pb
Cd
Fe
Liver
Premonsoon
6.113
8.765
16.419 3.264 40.715 1.564 0.413 160.262
Monsoon
5.067
3.909
9.825
2.862 11.291 0.501 0.297 130.012
Postmonsoon
6.052
5.616
10.326 3.934 17.235 1.968 0.368 140.396
Muscle
Premonsoon
5.203
11.415 25.102 2.436 9.837
1.125 0.098 98.147
Monsoon
3.051
5.617
41.016 1.978 8.371
1.161 0.375 39.372
Postmonsoon
4.690
8.168
28.132 2.156 12.192 0.160 0.105 95.261
