|Year : 2014 | Volume
| Issue : 3 | Page : 117-119
Depth profile of Cr, Cu, Co, Ni, and Pb in the sediment cores of Mumbai Harbour Bay
D Madhuparna, P Hemalatha, Sanu S Raj, SK Jha, RM Tripathi
Environmental Radiation Monitoring Section, Health Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
|Date of Web Publication||10-Apr-2015|
Environmental Radiation Monitoring Section, Health Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
A study was carried out in the Mumbai Harbour Bay sediment cores to measure concentration of biologically significant toxic elements such as Cr, Cu, Co, Ni, and Pb and to find out pattern of distribution in the sediment bed to follow the accumulation of elements with respect to depth. The range of concentration values of Cr, Cu, Co, Ni, and Pb in the sediment core fractions collected from three locations from Mumbai Harbour Bay sediment versus depth were plotted. Among the five elements, the concentration of Cr and Ni was found to be comparatively higher than all other elements with a range of 36 to 483 ppm and 24 to 155 ppm, respectively. The concentration of Co and Pb was observed to be lower in all the sediment cores and also evenly distributed in all the fractions with a range of 12-40 ppm and 10-270 ppm, respectively. Cu showed a range of 5-300 ppm.
Keywords: Depth profile, sediment core, toxic elements
|How to cite this article:|
Madhuparna D, Hemalatha P, Raj SS, Jha S K, Tripathi R M. Depth profile of Cr, Cu, Co, Ni, and Pb in the sediment cores of Mumbai Harbour Bay. Radiat Prot Environ 2014;37:117-9
|How to cite this URL:|
Madhuparna D, Hemalatha P, Raj SS, Jha S K, Tripathi R M. Depth profile of Cr, Cu, Co, Ni, and Pb in the sediment cores of Mumbai Harbour Bay. Radiat Prot Environ [serial online] 2014 [cited 2020 May 30];37:117-9. Available from: http://www.rpe.org.in/text.asp?2014/37/3/117/154864
| Introduction|| |
Coastal sediments act as ultimate sink for trace metals that are discharged into the aquatic environment.  Sources of environmental contaminants to the coastal system are numerous and may enter the estuarine environment via a number of pathways.  Hence, estuarine and coastal sediments near industrial and urban areas are contaminated to some extent with heavy metals, which are toxic to biota.  High level of heavy metals is attributed to anthropogenic influences, rather than natural enrichment of the sediment by geological weathering.  The occurrence of elevated levels of trace metals in sediments is a good indication of man-induced pollution. Sediments being in constant flux with the overlying water column, integrate contaminants over a period of time. Hence, the analysis of the distribution of heavy metals in coastal sediments enables detection of pollutants and also will provide the spatial and temporal history of pollutants in a particular region or ecosystem.  The present study has been carried out in the sediment cores of Mumbai Harbour Bay to estimate the toxic trace element content of the sediment and to find out how they are distributed in the sediment with respect to depth. Mumbai Harbour Bay, located in the West cost of India, assumes importance as it receives the low-level nuclear wastes from Bhabha Atomic Research Centre (BARC) and industrial and domestic sewage waste from the surrounding dwellings. Furthermore, the bay is extensively exploited for various commercial activities like fishing, transportation of goods, movement of boats, etc., Depth wise distribution of some important elements such as Cr, Cu, Co, Ni, and Pb were estimated in the core sediments from different locations in Mumbai Harbour Bay. The knowledge of these elemental distributions assumes significance since some of the elements are stable counterparts of the radioactive fission and activation products released into the environment by nuclear wastes (e.g. Co-59 [stable] and Co-60, Ni-58.6 [stable] and Ni-63, Cr-52 [stable] and Cr-51 etc.,). Hence, the depth wise distribution of trace element will provide knowledge of temporal and spatial variability of these elements in the sediment bed and will be useful in predicting the physicochemical behavior of some toxic elements under changing conditions.
| Materials and methods|| |
Core sediment samples of 40 cm length were collected using a boat in Mumbai Harbor Bay from three representative locations that is, Trombay Navel Jetty (TNJ-location-1), near discharge point of CIRUS, (BARC, location-3), and in between these two location at near plutonium plant (PP-location-2). Location-1 (TNJ) is prone to a lot of human activities due to its proximity to Thane creek bridge, with movement of boats and fishing activities as mainly used by the local fishermen. Location-3 (CIRUS) receives the treated low-level radioactive liquid discharges from BARC nuclear facility. The 2 nd location is in between these two locations and 3 km away from both and comparatively less approached by human activities. Core samples were collected using a specially designed polyvinyl chloride pipe core sampler of 30 cm diameter. On board, the core samples were cut into 4 cm fractions and sealed in a polythene bag and brought to the laboratory. The fractions were dried at 110°C in air oven and powdered to get homogenized material. The dried sediment was ashed in a muffle furnace at 450°C to remove organic matter. One gram of each of the ashed samples was completely destructed with 4 ml of concentrated nitric acid and 4 ml of hydrofluoric acid using microwave digester (Model No-Sineo-MDS10) Sineo Microwave Chemistry Technology (Sanghai) Co. Ltd. The digested samples were evaporated to dryness, converted to chloride medium using HCl and made to 25 ml volume with 0.04N HCl. The elemental concentration in the samples was estimated by atomic absorption spectrometer, ( model GBC Avanta) GBC Scientific Equipment (USA) LLC. Toxic elements such as Cr, Cu, Co, Ni, and Pb were estimated in all the core sediment sample fractions at wavelength 425.4 nm, 222.6 nm, 304.4 nm, 352.4 nm, and 283.3 nm respectively. A reagent blank was also prepared for each batch of analysis and run along with the samples in atomic absorption spectrometer. Wherever it was required, further dilutions were done using double distilled water. All measurements were done in triplicate, and quality assurance was done by running standards as unknown after every 10 samples. Results were within an uncertainty of 2%.
| Results and discussion|| |
[Figure 1] [Figure 2] [Figure 3] show the depth wise distribution of five elements Cr, Cu, Co, Ni, Pb analyzed in the sediment core fractions collected from three locations of Mumbai Harbour Bay. In all the locations, Pb and Co concentration was found to be uniformly distributed in all core fractions. At station 2 in the last fraction at 32 cm depth, elevated concentration of Pb with a value of 270 ppm was observed. Compared to other elements, Pb and Co concentration was found to be less in the core fractions. In general, the concentration of the five trace element analyzed was in the increasing order of Cr > Ni > Cu > Co > Pb at locations 1 and 2 (TNJ and PP), and in location-3 (CIRUS), the concentration of the elements was in the order of Ni > Cr > Cu > Co > Pb showing higher concentration of Ni. [Figure 1] shows the concentration of elements in the sediment core fractions collected from TNJ. Pb was observed to be in the range of 12-18 ppm. A slightly higher Co value of 40 ppm was observed in station 2 in the last fraction at 32 cm depth. In location-3 also, the Pb and Co distribution was observed to be uniform with respect to depth.
Distribution of Cr, Cu, and Ni in the core sediment
The pattern of distribution of Cr, Cu, and Ni in the cores was observed to be different for the 3 locations. In location-1, Cu, Cr, and Ni show a similar trend of distribution and fluctuation with respect to depth. However, all these three elements show maximum concentration in the last fraction. The last fraction of location-1 showed a high value of Cu concentration as 300 ppm as against the 16-60 ppm range observed in other depth fractions of the core. In location-3, Cr, Cu, and Ni in the core fractions were observed to be present without any particular trend with respect to depth. However, the patterns of distribution of the elements in the core sediment were observed to be similar with respect to depth. The distribution of Cr, Ni, and Cu with respect to depth showed a similar pattern in location-1 and -2 while, at location-3, a uniform pattern of distribution was observed with depth. Ni content at location-3 was observed to be present in higher concentration in the top fraction in the range of 105 to125 up to a depth of 16 cm, and then it gradually reduced in the last fraction. The last fraction of location-1 and -2 (TNJ and near PP) showed similar concentration of Ni as 119 and 155 ppm, respectively. At location-2, Cr concentration was observed to be in the increasing order from a depth of 16 cm to 32 cm. Similar values in the range of 80-150 ppm for Ni, Cu and Cr in the Mumbai Harbour Bay sediments have been reported by Hemalatha and Desai.  This explains the fact that the location-2 (PP) is less prone to disturbance as it is away from human activities and expected to be affected mainly by tidal influence of the bay. While at location-1 (TNJ) due to a lot of human activities and tidal activity, might be a reason for the disturbance of the sediment bed. Similarly at location-3 (CIRUS) near the discharge point, the sediment is expected to be disturbed with input of waste water discharges from BARC releases and also subjected to tidal water. Apart from this, tidal action which is the major cause in the sweeping of the top layer minerals, the pattern of distribution of elements in the sediment bed is attributed to chemical composition of the sediment, the mineralogy, organic content, etc., which has to be investigated to predict the impact.
| Conclusions|| |
The toxic elements such as Cr, Cu, Co, Ni, and Pb were estimated in the core sediment of Mumbai Harbour Bay from three locations. The element concentration in the sediment core was in the order of Cr > Ni > Cu > Co > Pb. A uniform distribution of Pb and Co was observed in the core with respect to depth. The last fraction of the sediment was observed to contain higher concentration of Ni, Cr, and Cu. A maximum value of 483 ppm was observed for Cr in the PP location. At TNJ location, a maximum value of 300 ppm for Cu was observed in the last fraction at 32 cm depth. The vertical distribution of Cr and Ni in the sediment was observed to be in a similar pattern with respect to depth in all the locations. Location near CIRUS and TNJ showed fluctuation in the distribution of the elements with respect to depth. Location near PP showed lesser fluctuation which can be attributed that this location is far away from the human activities.
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[Figure 1], [Figure 2], [Figure 3]