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The distributions down the sediment column of radionu- clides such as 7*4Th, 7!°Pb and '3’Cs, which are con- tinuously input at the sediment-water interface, is

Figure 2 The distributions down the sediment column of radionu- clides such as 7*4Th, 7!°Pb and '3’Cs, which are con- tinuously input at the sediment-water interface, is

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Fig 1 Map of Mumbai Harbour Bay showing the sampling site The Bay is characterized by abundant mudflats and exhibits good coverage of mangroves. However, in recent years the mangrove areas are being intensively targeted for dumping garbage, disposal of sewage and also overexploited by salt industries, fishing, navigation and recreationa activities. In the past, the only source of waste water to the bay was from domestic discharge. But in recent years development of nearby areas for residential purposes and industrial complexes has resulted in increasing level o pollution in the bay. Kulkarni et al. (2010) studied biologica and environmental characteristics of mangrove habitats around the creek and found Avicennia marina to be the dom- inant mangrove species. Because of poor abundance and di- versity of mangroves, the authors classified the area as a Six sediment cores were collected from three different locations within 3 nautical mile area (from the discharge point) in the month of December, 2011 as per standard protocols adopted by International Atomic Energy Agency (IAEA-TECDOC-1360 2003). Figure 1 shows the map of Mumbai Harbour Bay show- ing the sampling sites viz CS-1, CS-2 and CS-3. The sampling was done by using in-house fabricated sampler made of acrylic
Fig 1 Map of Mumbai Harbour Bay showing the sampling site The Bay is characterized by abundant mudflats and exhibits good coverage of mangroves. However, in recent years the mangrove areas are being intensively targeted for dumping garbage, disposal of sewage and also overexploited by salt industries, fishing, navigation and recreationa activities. In the past, the only source of waste water to the bay was from domestic discharge. But in recent years development of nearby areas for residential purposes and industrial complexes has resulted in increasing level o pollution in the bay. Kulkarni et al. (2010) studied biologica and environmental characteristics of mangrove habitats around the creek and found Avicennia marina to be the dom- inant mangrove species. Because of poor abundance and di- versity of mangroves, the authors classified the area as a Six sediment cores were collected from three different locations within 3 nautical mile area (from the discharge point) in the month of December, 2011 as per standard protocols adopted by International Atomic Energy Agency (IAEA-TECDOC-1360 2003). Figure 1 shows the map of Mumbai Harbour Bay show- ing the sampling sites viz CS-1, CS-2 and CS-3. The sampling was done by using in-house fabricated sampler made of acrylic
Fig 3 Logarithmic plot of activity levels of *!°Pb,, against linear depth (kgm ~°) of sediment (a) Core 1 (b) Core 2 and (c) Core 3 collected from site CS-1, CS-2 and CS-3 respectively
Fig 3 Logarithmic plot of activity levels of *!°Pb,, against linear depth (kgm ~°) of sediment (a) Core 1 (b) Core 2 and (c) Core 3 collected from site CS-1, CS-2 and CS-3 respectively
et al. 2014a, b) whereas sand abundances increases as depth increases. The overall mean content of sand, silt and clay in cores of studied area ranged from 0.10 to 11.94 % (mean: 5.27 +4.98 %), 69.58-76.48 % (mean: 72.66 +2.57 %) and 16.60— 25.65 % (mean: 22.10+3.1 %) respectively (Kumar et al. 2014a, b). The clay minerals composition in the studied area also indicated that chlorite and illite as predominant in the sediments. Moreover, quite appreciable amounts of calcite, dolomite Ca—montmorillonite, talc, amphiboles, quartz and Na-—montmorillonite were also present. The positive correla- tion with silt and clay clearly indicates that radionuclides are Fig 4 Logarithmic plot of activity levels of '*’Cs against linear depth (kgm *) of sediment (a) Core 1 (b) Core 2 and (e) Core 3 collected from site CS-1, CS-2 and CS-3 respectively
et al. 2014a, b) whereas sand abundances increases as depth increases. The overall mean content of sand, silt and clay in cores of studied area ranged from 0.10 to 11.94 % (mean: 5.27 +4.98 %), 69.58-76.48 % (mean: 72.66 +2.57 %) and 16.60— 25.65 % (mean: 22.10+3.1 %) respectively (Kumar et al. 2014a, b). The clay minerals composition in the studied area also indicated that chlorite and illite as predominant in the sediments. Moreover, quite appreciable amounts of calcite, dolomite Ca—montmorillonite, talc, amphiboles, quartz and Na-—montmorillonite were also present. The positive correla- tion with silt and clay clearly indicates that radionuclides are Fig 4 Logarithmic plot of activity levels of '*’Cs against linear depth (kgm *) of sediment (a) Core 1 (b) Core 2 and (e) Core 3 collected from site CS-1, CS-2 and CS-3 respectively
derived from both radionuclides. High values of D, at partic- ular cores indicate that there is the prevalence of sediment deposit feeding organisms at the interface of seawater -sedi- ment. Literatures reported that deep sea sediment with sedi- mentation rates in the range of 0.001 and 0.01 cmy | yield Dy values in the range of 0.1 and 1 cm’y | (Tromp et al. 1995). Such Dy, values are thus more than one order of magnitude smaller than the coastal regions.
derived from both radionuclides. High values of D, at partic- ular cores indicate that there is the prevalence of sediment deposit feeding organisms at the interface of seawater -sedi- ment. Literatures reported that deep sea sediment with sedi- mentation rates in the range of 0.001 and 0.01 cmy | yield Dy values in the range of 0.1 and 1 cm’y | (Tromp et al. 1995). Such Dy, values are thus more than one order of magnitude smaller than the coastal regions.
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Earth SciencesEnvironmental ScienceCoastal Conservation
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