Rejomon George - Academia.edu (original) (raw)
Papers by Rejomon George
Hydrography and the associated chemical and biological responses of the Cochin coastal waters wer... more Hydrography and the associated chemical and biological responses of the Cochin coastal waters were studied during the monsoon, post-monsoon, and pre-monsoon periods. During monsoon, the surface waters were cold (SST = 27.2-27.8°C), of low salinity (salinity = 30.3-33.5 psu), and oxygen deficient (O2 = 178-180 μmol/L), with a high enrichment of nutrients (NO3 ≥ 4 μmol/L, PO4 ≥ 1.2 μmol/L, and SiO4 ≥ 6 μmol/L), which indicates a hypertrophic environment (chlorophyll a ≥ 5 mg/m 3). During post-monsoon season, the surface waters were slightly warmer (SST = 28.6-29.2° C), of low salinity (salinity = 30.8-34.0 psu), and less oxygenated (O2 = 185-189 μmol/L), with a moderate enrichment of nutrients (NO3 ≥ 2 μmol/L, PO4 ≥ 1 μmol/L, and SiO4 ≥ 4 μmol/L), which indicates a eutrophic environment (chlorophyll a = 4 5 mg/m3). During pre-monsoon season, the surface waters were very warm (SST = 29.5-30.2° C), of low salinity (salinity = 31.3-34.3 psu), and the oxygen level was under saturated (O2 ...
Environmental Monitoring and Assessment, 2009
The concentration of Fe, Co, Ni, Cu, Zn, Cd and Pb in the muscle tissue of marine fishes like Lat... more The concentration of Fe, Co, Ni, Cu, Zn, Cd and Pb in the muscle tissue of marine fishes like Lates calcarifer, Nemipterus japonicus, Caranx melampygus, Rastrelliger kanagurta and Cyanoglossus macrostomus was estimated from samples collected in the continental shelf waters off Kochi and Mangalore on southwest coast of India. Species-specific and spatially heterogeneous patterns of tissue metals loads were apparent within the pelagic and demersal fish species for the two regions. The concentration ranges of Fe (541.60 to 649.60 ppm), Ni (12.12 to 13.92 ppm) and Cu (3.09 to 3.62 ppm) were higher in the demersal species Caranx melampygus,whereas Co (9.10 to 11.80 ppm) and Zn (79.30 to 84.30 ppm) were higher in the pelagic species Lates calcarifer and Cd (4.35 to 6.38 ppm) were higher in the demersal species Nemipterus japonicus, possibly due to enhanced bioavailability of these metals from ecological processes associated with upwelling during the summer monsoon. The fish species showed a great capacity to accumulate metals, with highest bioaccumulation for the essential element iron and lowest bioaccumulation for the non-essential element lead. Among the demersal species, Caranx melampygus and Nemipterus japonicus had high concentration factors for the metals Fe (280268 to 322808), Ni (88252 to 96891), Cu (2351 to 2600) and Cd (29637 to 32404). In contrast, the pelagic species Lates calcarifer and Rasterelliger kanagurta had high concentration factors for the metals Zn (40812 to 46892), Co (280285 to 423037) and Pb (854 to 1404).
Biogeosciences …
1 Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, 560 012, India 2 Nat... more 1 Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, 560 012, India 2 National Institute of Oceanography, Regional Centre, Council of Scientific and Industrial Research, Dr. Salim Ali Road, Kochi, 682 018, India 3 Centre for Earth Sciences, Indian ...
Trace metal contents in zooplankton samples were estimated as a part of Marine Research- Living R... more Trace metal contents in zooplankton samples were estimated as a part of Marine Research- Living Resource Programme (MRLR) programme at 24 stations to establish the importance of these metals in the Bay of Bengal. The average concentration of Fe, Co, Ni, Cu, Zn, Cd and Pb in zooplankton from the Bay of Bengal indicates that it is slightly enriched in coastal samples than offshore samples. The heavy river discharge in the east coast of India might be related to the increased metal bioavailabilities in seawater and hence an increased uptake of metals by zooplankton from coastal areas than offshore areas. The zooplankton species examined showed great accumulations of metals, with bioaccumulation factors in the range >15,000 to 40,000,000 with respect to the concentrations (soluble fractions) in marine waters. Metal concentrations recorded in the Bay of Bengal zooplankton may be used as background levels for future studies, a body of water about which information is still very scarce.
TIJ's Research Journal of Science & IT Management - RJSITM, 2018
Muscles, gills, and livers of the fish Sardinella longiceps , Rastrelliger kanagurta , Lates calc... more Muscles, gills, and livers of the fish Sardinella longiceps , Rastrelliger kanagurta , Lates calcarifer , Cyanoglossus macrostomus , Caranx melampygus , and Nemipterus japonicus from the coastal waters of Cochin, India, were evaluated for the trace metals, iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) during the monsoon, post-monsoon, and pre-monsoon periods. The monsoon, post-monsoon and pre-monsoon ranges of the metal concentrations in the muscles, gills, and livers of fish were respectively as follows: Fe (445.15 to 817.85 µg/g, 503.85 to 940.56 µg/g, and 578.75 to 1144.85 µg/g); Co (6.18 to 17.18 µg/g, 7.46 to 24.28 µg/g, and 10.65 to 41.65 µg/g); Ni (8.66 to 18.25 µg/g, 12.56 to 41.17 µg/g, and 21.75 to 106.46 µg/g); Cu (2.75 to 5.38 µg/g, 9.06 to 29.05 µg/g, and 17.57 to 43.27 µg/g); Zn (38.35 to 99.25 µg/g, 65.96 to 197.95 µg/g, and 100.48 to 431.67 µg/g); Cd (1.45 to 7.56 µg/g, 1.96 to 13.37 µg/g, and 2.45 to 23.36 µg/g); and Pb (1....
Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surf... more Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surficial sediments of the Cochin backwaters were studied during both monsoon and pre-monsoon periods. Spatial variations were in accordance with textural charaterstics and organic matter content. A principal component analysis distinguished three zones with different metal accumulation capacity: (i) highest levels in north estuary, (ii) moderate levels in central zone, and (iii) lowest levels in southern part. Trace metal enrichments are mainly due to anthropogenic contribution of industrial, domestic, and agricultural effluents, whose effect is enhanced by settling of metals due to organic flocculation and inorganic precipitation associated with salinity changes. Enrichments factors using Fe as a normalizer showed that metal contamination was the product of anthropogenic activities. An assessment of degree of pollution-categorized sediments as moderately polluted with Cu and Pb, moderately-to-heavily polluted with Zn, and heavily-to-extremely polluted with Cd. Concentrations at many sites largely exceed NOAA ERL (e.g., Cu, Cr, and Pb) or ERM (e.g., Cd, Ni, and Zn). This means that adverse effects for benthic organisms are possible or even highly probable.
Environmental …, 2008
Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Livin... more Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Living Resource program at 24 stations in the Bay of Bengal (November, 2002) and 29 stations in the Arabian Sea (September-October, 2003) during the Cruises 209 and 217 of the Fishery and Oceanographic Research Vessel Sagar Sampada. The average metal concentrations in the Bay of Bengal zooplankton (Fe, 14,073 µg g −1 ; Co, 24.2 µg g −1 ; Ni, 29.5 µg g −1 ; Cu, 46.2 µg g −1 ; Zn, 2000 µg g −1 ; Cd, 18.7 µg g −1 ; and Pb, 6.55 µg g −1) were found to be higher of comparable magnitudes than the Arabian Sea zooplankton (Fe, 1786 µg g −1 ; Co, 14.2 µg g −1 ; Ni, 18.6 µg g −1 ; Cu, 21.5 µg g −1 ; Zn, 374 µg g −1 ; Cd, 16.5 µg g −1 ; and Pb, 4.0 µg g −1). The spatial variability of metal contents in zooplankton from both basins indicates that it is markedly enriched in coastal samples than offshore samples. The metal enrichment in zooplankton from the coastal areas of the eastern Arabian Sea occurs due to a combined effect of upwelling, riverine, and anthropogenic sources, whereas the latter two are only dominating in the coastal Bay of Bengal zooplankton. A comparison of average trace metal concentrations in the zooplankton from the Arabian Sea and Bay of Bengal showed that the enrichment of Fe, Zn, Cd, Ni, Cu, and Pb in the Bay of Bengal zooplankton may be due to high bioaccumulation factor of these elements, whereas the slight Co enrichment may be due to the bioavailability of this metal in the seawater.
Environmental …, 2008
Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Livin... more Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Living Resource program at 24 stations in the Bay of Bengal (November, 2002) and 29 stations in the Arabian Sea (September-October, 2003) during the Cruises 209 and 217 of the Fishery and Oceanographic Research Vessel Sagar Sampada. The average metal concentrations in the Bay of Bengal zooplankton (Fe, 14,073 µg g −1 ; Co, 24.2 µg g −1 ; Ni, 29.5 µg g −1 ; Cu, 46.2 µg g −1 ; Zn, 2000 µg g −1 ; Cd, 18.7 µg g −1 ; and Pb, 6.55 µg g −1) were found to be higher of comparable magnitudes than the Arabian Sea zooplankton (Fe, 1786 µg g −1 ; Co, 14.2 µg g −1 ; Ni, 18.6 µg g −1 ; Cu, 21.5 µg g −1 ; Zn, 374 µg g −1 ; Cd, 16.5 µg g −1 ; and Pb, 4.0 µg g −1). The spatial variability of metal contents in zooplankton from both basins indicates that it is markedly enriched in coastal samples than offshore samples. The metal enrichment in zooplankton from the coastal areas of the eastern Arabian Sea occurs due to a combined effect of upwelling, riverine, and anthropogenic sources, whereas the latter two are only dominating in the coastal Bay of Bengal zooplankton. A comparison of average trace metal concentrations in the zooplankton from the Arabian Sea and Bay of Bengal showed that the enrichment of Fe, Zn, Cd, Ni, Cu, and Pb in the Bay of Bengal zooplankton may be due to high bioaccumulation factor of these elements, whereas the slight Co enrichment may be due to the bioavailability of this metal in the seawater.
Applied Ecology and Environmental Research, 2007
Trace metal contents in zooplankton samples were estimated as a part of Marine Research-Living Re... more Trace metal contents in zooplankton samples were estimated as a part of Marine Research-Living Resource Programme (MRLR) programme at 24 stations to establish the importance of these metals in the Bay of Bengal. The average concentration of Fe, Co, Ni, Cu, Zn, Cd and Pb in zooplankton from the Bay of Bengal indicates that it is slightly enriched in coastal samples than offshore samples. The heavy river discharge in the east coast of India might be related to the increased metal bioavailabilities in seawater and hence an increased uptake of metals by zooplankton from coastal areas than offshore areas. The zooplankton species examined showed great accumulations of metals, with bioaccumulation factors in the range >15,000 to 40,000,000 with respect to the concentrations (soluble fractions) in marine waters. Metal concentrations recorded in the Bay of Bengal zooplankton may be used as background levels for future studies, a body of water about which information is still very scarce.
Environmental Forensics, 2016
Environmental Earth Sciences, 2012
ABSTRACT Hydrography of the eastern Arabian Sea and associated chemical and biological responses ... more ABSTRACT Hydrography of the eastern Arabian Sea and associated chemical and biological responses were studied during the withdrawal phase of summer monsoon 2003. The shelf region off the southwest coast of India (10°N–15°N) continued to exhibit upwelling of colder (<28.5 °C), nutrient rich (nitrate >2.0 μM, phosphate >0.8 μM, silicate >4.0 μM) and relatively low oxygenated waters (~180 μM). The vertical advection of nutrients, coupled with anthropogenic terrestrial inputs, enhanced the levels of chlorophyll and primary productivity near the coastal margin off Cochin. The influence of both natural and anthropogenic nutrient loadings on the coastal system of the western continental shelf of India leads to eutrophication and hypoxia with negative impacts on the environment in general and fisheries in particular.
The Scientific World Journal, 2012
Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surf... more Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surficial sediments of the Cochin backwaters were studied during both monsoon and pre-monsoon periods. Spatial variations were in accordance with textural charaterstics and organic matter content. A principal component analysis distinguished three zones with different metal accumulation capacity: (i) highest levels in north estuary, (ii) moderate levels in central zone, and (iii) lowest levels in southern part. Trace metal enrichments are mainly due to anthropogenic contribution of industrial, domestic, and agricultural effluents, whose effect is enhanced by settling of metals due to organic flocculation and inorganic precipitation associated with salinity changes. Enrichments factors using Fe as a normalizer showed that metal contamination was the product of anthropogenic activities. An assessment of degree of pollution-categorized sediments as moderately polluted with Cu and Pb, moderately...
Biogeosciences Discussions, 2010
Hydrographic characteristics of the southwest coast of India and its adjoining Cochin backwaters ... more Hydrographic characteristics of the southwest coast of India and its adjoining Cochin backwaters (CBW) were studied during the summer monsoon period. Anomalous formation of anoxia and denitrification were observed in the bottom layers of CBW, which have not been previously reported elsewhere in any tropical estuarine systems. The prevalent upwelling in the Arabian Sea (AS) brought cool, high saline, oxygen deficient and nutrient-rich waters towards the coastal zone and bottom layers of CBW during the high tide. High freshwater discharge in the surface layers brought high amount of nutrients and makes the CBW system highly productive. Intrusion of AS waters seems to be stronger towards the upstream end (∼15 km), than had been previously reported, as a consequence of the lowering of river discharges and deepening of channels in the estuary. Time series measurements in the lower reaches of CBW indicated a low mixing zone with increased stratification, 3 h after the high tide (highest high tide) and high variation in vertical mixing during the spring and neap phases. The upwelled waters (O 2 ≤ 40 µM) intruded into the estuary was found to lose more oxygen during the neap phase (suboxic O 2 ≤ 4 µM) than spring phase (hypoxic O 2 ≤ 10 µM). Increased stratification coupled with low ventilation and presence of high organic matter have resulted in an anoxic condition (O 2 = 0), 2-6 km away from barmouth of the estuary and leads to the formation of hydrogen sulphide. The reduction of nitrate and formation of nitrite within the oxygen deficient waters indicated strong denitrification intensity in the estuary. The expansion of oxygen deficient zone, denitrification and formation of hydrogen sulphide may lead to a destruction of biodiversity and an increase of green house gas emissions from this region.
Biogeosciences Discussions, 2010
The intensification of the natural coastal hypoxic zone over the western Indian shelf in the rece... more The intensification of the natural coastal hypoxic zone over the western Indian shelf in the recent years and its impact on the biogeochemistry and marine life is a matter of concern. This study examines the influence of the seasonal oxygen deficiency on the phosphorus geochemistry of the surface sediments along the western continental shelf of India (WCSI). Speciation of phosphorus along with the geochemical characteristics (total organic carbon-TOC, total nitrogen-TN, and total phosphorus-TP) of the surface sediments and the hydrography of the western continental shelf of India (WCSI) were studied, during late summer monsoon (LSM) and spring intermonsoon (SIM). The hydrography of the WCSI revealed upwelling and associated seasonal oxygen deficiency with denitrifying suboxic conditions along the inner shelf and hypoxic conditions along the outer shelf. High concentrations of dissolved phosphate (PO 4) and dissolved Iron (Fe) were also observed in the subsurface water of the inner shelf during LSM. The shelf water of the WCSI was oligotrophic and oxygen rich during SIM. A latitudinal enrichment of TOC, TN and TP in the surface sediments was observed at 13-17 • N, along the WCSI during LSM, where seasonal suboxia was intense. Authigenic apatite bound phosphorus (P aut) was the major phosphorus species along the WCSI during LSM whereas detrital flourapatite bound phosphorus (P det) was the major species during SIM. Substantial depletion of reactive iron(III)-bound phosphorus (∆P Fe) was observed in the surface sediments of the WCSI during LSM which showed significant correlation with the enrichment of PO 4 (∆PO 4) in the overlying water during LSM compared to SIM. PO 4 diffusing into the water column from the sediments by reductive dissolution of P Fe probably leads to high dissolved PO 4 along the inner shelf water during LSM which agrees with the existing hypothesis. Hence, phosphorus geochemistry of the surface sediments plays a major role in the biogeochemical cycling of phosphorus during periods of seasonal oxygen deficiency along the WCSI. Similar studies carried out along the eastern continental shelf of India (ECSI), where any kind of seasonal oxygen deficiency has not been reported yet, showed an abundance of 6090
Journal of Coastal Research, 2008
Even though continental margins cover only about 7-9% of the world ocean area, they are important... more Even though continental margins cover only about 7-9% of the world ocean area, they are important sites for organic carbon accumulation and hence play a major role in biogeochemical carbon cycling. Surface sediments from the western and eastern continental shelves of India were studied for their total organic matter content and the labile constituents such as total carbohydrates and proteins to get a better understanding of the hydrological and biogeochemical differences of the two regions on the nature of organic matter reaching the surface sediments. The sampling along the west coast was done during September-October 2003, when upwelling signatures were found to be still persisting along the shelf as evidenced by the low-oxygenated, nutrient-rich surface waters. The eastern shelf was sampled during November-December 2002. The shelf was found to be oxygen saturated and oligotrophic during the season. The surface sediments of the west coast contained a greater quantity of total organic matter when compared to the east coast, but the percentages of labile constituents of total organic matter in the sediments were found to be higher in the east coast by a factor of three as compared to the west coast. The differences in the productivity patterns and the hydrographical conditions were found to exert a major influence on the quantity and composition of organic matter in the surface sediments of the western and eastern continental shelves of India.
Environmental Monitoring and Assessment, 2013
Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".
Environmental Monitoring and Assessment, 2012
The distribution and accumulation of trace metals in the sediments of the Cochin estuary during t... more The distribution and accumulation of trace metals in the sediments of the Cochin estuary during the pre-monsoon, monsoon and post-monsoon periods were investigated. Sediment samples from 14 locations were collected and analysed for the metal contents (Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb), organic carbon, total nitrogen, total sulphur and grain size. The data were processed using statistical tools like correlation, factor and cluster analysis. The study revealed an enrichment of Cd and Zn in the study area particularly at station 2, which is confirmed by enrichment factor, contamination factor and geoaccumulation index. The factor analysis revealed that the source of Cd and Zn may be same. The study indicated that the spatial variation for the metals like Mg, Cr, Fe, Co, Ni, Cu, Zn, Cd and Pb were predominant unlike Mn which shows a temporal variation. The strong association of trace metals with Fe and Mn hydroxides and oxides are prominent along the Cochin estuary. The anthropogenic inputs of industrial effluents mainly control the trace metals enrichment in the Cochin estuary.
Environmental Monitoring and Assessment, 2012
Environmental Monitoring and Assessment, 2008
Hydrography and the associated chemical and biological responses of the Cochin coastal waters wer... more Hydrography and the associated chemical and biological responses of the Cochin coastal waters were studied during the monsoon, post-monsoon, and pre-monsoon periods. During monsoon, the surface waters were cold (SST = 27.2-27.8°C), of low salinity (salinity = 30.3-33.5 psu), and oxygen deficient (O2 = 178-180 μmol/L), with a high enrichment of nutrients (NO3 ≥ 4 μmol/L, PO4 ≥ 1.2 μmol/L, and SiO4 ≥ 6 μmol/L), which indicates a hypertrophic environment (chlorophyll a ≥ 5 mg/m 3). During post-monsoon season, the surface waters were slightly warmer (SST = 28.6-29.2° C), of low salinity (salinity = 30.8-34.0 psu), and less oxygenated (O2 = 185-189 μmol/L), with a moderate enrichment of nutrients (NO3 ≥ 2 μmol/L, PO4 ≥ 1 μmol/L, and SiO4 ≥ 4 μmol/L), which indicates a eutrophic environment (chlorophyll a = 4 5 mg/m3). During pre-monsoon season, the surface waters were very warm (SST = 29.5-30.2° C), of low salinity (salinity = 31.3-34.3 psu), and the oxygen level was under saturated (O2 ...
Environmental Monitoring and Assessment, 2009
The concentration of Fe, Co, Ni, Cu, Zn, Cd and Pb in the muscle tissue of marine fishes like Lat... more The concentration of Fe, Co, Ni, Cu, Zn, Cd and Pb in the muscle tissue of marine fishes like Lates calcarifer, Nemipterus japonicus, Caranx melampygus, Rastrelliger kanagurta and Cyanoglossus macrostomus was estimated from samples collected in the continental shelf waters off Kochi and Mangalore on southwest coast of India. Species-specific and spatially heterogeneous patterns of tissue metals loads were apparent within the pelagic and demersal fish species for the two regions. The concentration ranges of Fe (541.60 to 649.60 ppm), Ni (12.12 to 13.92 ppm) and Cu (3.09 to 3.62 ppm) were higher in the demersal species Caranx melampygus,whereas Co (9.10 to 11.80 ppm) and Zn (79.30 to 84.30 ppm) were higher in the pelagic species Lates calcarifer and Cd (4.35 to 6.38 ppm) were higher in the demersal species Nemipterus japonicus, possibly due to enhanced bioavailability of these metals from ecological processes associated with upwelling during the summer monsoon. The fish species showed a great capacity to accumulate metals, with highest bioaccumulation for the essential element iron and lowest bioaccumulation for the non-essential element lead. Among the demersal species, Caranx melampygus and Nemipterus japonicus had high concentration factors for the metals Fe (280268 to 322808), Ni (88252 to 96891), Cu (2351 to 2600) and Cd (29637 to 32404). In contrast, the pelagic species Lates calcarifer and Rasterelliger kanagurta had high concentration factors for the metals Zn (40812 to 46892), Co (280285 to 423037) and Pb (854 to 1404).
Biogeosciences …
1 Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, 560 012, India 2 Nat... more 1 Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, 560 012, India 2 National Institute of Oceanography, Regional Centre, Council of Scientific and Industrial Research, Dr. Salim Ali Road, Kochi, 682 018, India 3 Centre for Earth Sciences, Indian ...
Trace metal contents in zooplankton samples were estimated as a part of Marine Research- Living R... more Trace metal contents in zooplankton samples were estimated as a part of Marine Research- Living Resource Programme (MRLR) programme at 24 stations to establish the importance of these metals in the Bay of Bengal. The average concentration of Fe, Co, Ni, Cu, Zn, Cd and Pb in zooplankton from the Bay of Bengal indicates that it is slightly enriched in coastal samples than offshore samples. The heavy river discharge in the east coast of India might be related to the increased metal bioavailabilities in seawater and hence an increased uptake of metals by zooplankton from coastal areas than offshore areas. The zooplankton species examined showed great accumulations of metals, with bioaccumulation factors in the range >15,000 to 40,000,000 with respect to the concentrations (soluble fractions) in marine waters. Metal concentrations recorded in the Bay of Bengal zooplankton may be used as background levels for future studies, a body of water about which information is still very scarce.
TIJ's Research Journal of Science & IT Management - RJSITM, 2018
Muscles, gills, and livers of the fish Sardinella longiceps , Rastrelliger kanagurta , Lates calc... more Muscles, gills, and livers of the fish Sardinella longiceps , Rastrelliger kanagurta , Lates calcarifer , Cyanoglossus macrostomus , Caranx melampygus , and Nemipterus japonicus from the coastal waters of Cochin, India, were evaluated for the trace metals, iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) during the monsoon, post-monsoon, and pre-monsoon periods. The monsoon, post-monsoon and pre-monsoon ranges of the metal concentrations in the muscles, gills, and livers of fish were respectively as follows: Fe (445.15 to 817.85 µg/g, 503.85 to 940.56 µg/g, and 578.75 to 1144.85 µg/g); Co (6.18 to 17.18 µg/g, 7.46 to 24.28 µg/g, and 10.65 to 41.65 µg/g); Ni (8.66 to 18.25 µg/g, 12.56 to 41.17 µg/g, and 21.75 to 106.46 µg/g); Cu (2.75 to 5.38 µg/g, 9.06 to 29.05 µg/g, and 17.57 to 43.27 µg/g); Zn (38.35 to 99.25 µg/g, 65.96 to 197.95 µg/g, and 100.48 to 431.67 µg/g); Cd (1.45 to 7.56 µg/g, 1.96 to 13.37 µg/g, and 2.45 to 23.36 µg/g); and Pb (1....
Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surf... more Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surficial sediments of the Cochin backwaters were studied during both monsoon and pre-monsoon periods. Spatial variations were in accordance with textural charaterstics and organic matter content. A principal component analysis distinguished three zones with different metal accumulation capacity: (i) highest levels in north estuary, (ii) moderate levels in central zone, and (iii) lowest levels in southern part. Trace metal enrichments are mainly due to anthropogenic contribution of industrial, domestic, and agricultural effluents, whose effect is enhanced by settling of metals due to organic flocculation and inorganic precipitation associated with salinity changes. Enrichments factors using Fe as a normalizer showed that metal contamination was the product of anthropogenic activities. An assessment of degree of pollution-categorized sediments as moderately polluted with Cu and Pb, moderately-to-heavily polluted with Zn, and heavily-to-extremely polluted with Cd. Concentrations at many sites largely exceed NOAA ERL (e.g., Cu, Cr, and Pb) or ERM (e.g., Cd, Ni, and Zn). This means that adverse effects for benthic organisms are possible or even highly probable.
Environmental …, 2008
Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Livin... more Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Living Resource program at 24 stations in the Bay of Bengal (November, 2002) and 29 stations in the Arabian Sea (September-October, 2003) during the Cruises 209 and 217 of the Fishery and Oceanographic Research Vessel Sagar Sampada. The average metal concentrations in the Bay of Bengal zooplankton (Fe, 14,073 µg g −1 ; Co, 24.2 µg g −1 ; Ni, 29.5 µg g −1 ; Cu, 46.2 µg g −1 ; Zn, 2000 µg g −1 ; Cd, 18.7 µg g −1 ; and Pb, 6.55 µg g −1) were found to be higher of comparable magnitudes than the Arabian Sea zooplankton (Fe, 1786 µg g −1 ; Co, 14.2 µg g −1 ; Ni, 18.6 µg g −1 ; Cu, 21.5 µg g −1 ; Zn, 374 µg g −1 ; Cd, 16.5 µg g −1 ; and Pb, 4.0 µg g −1). The spatial variability of metal contents in zooplankton from both basins indicates that it is markedly enriched in coastal samples than offshore samples. The metal enrichment in zooplankton from the coastal areas of the eastern Arabian Sea occurs due to a combined effect of upwelling, riverine, and anthropogenic sources, whereas the latter two are only dominating in the coastal Bay of Bengal zooplankton. A comparison of average trace metal concentrations in the zooplankton from the Arabian Sea and Bay of Bengal showed that the enrichment of Fe, Zn, Cd, Ni, Cu, and Pb in the Bay of Bengal zooplankton may be due to high bioaccumulation factor of these elements, whereas the slight Co enrichment may be due to the bioavailability of this metal in the seawater.
Environmental …, 2008
Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Livin... more Trace metal contents in zooplankton samples were estimated as a part of the Marine Research-Living Resource program at 24 stations in the Bay of Bengal (November, 2002) and 29 stations in the Arabian Sea (September-October, 2003) during the Cruises 209 and 217 of the Fishery and Oceanographic Research Vessel Sagar Sampada. The average metal concentrations in the Bay of Bengal zooplankton (Fe, 14,073 µg g −1 ; Co, 24.2 µg g −1 ; Ni, 29.5 µg g −1 ; Cu, 46.2 µg g −1 ; Zn, 2000 µg g −1 ; Cd, 18.7 µg g −1 ; and Pb, 6.55 µg g −1) were found to be higher of comparable magnitudes than the Arabian Sea zooplankton (Fe, 1786 µg g −1 ; Co, 14.2 µg g −1 ; Ni, 18.6 µg g −1 ; Cu, 21.5 µg g −1 ; Zn, 374 µg g −1 ; Cd, 16.5 µg g −1 ; and Pb, 4.0 µg g −1). The spatial variability of metal contents in zooplankton from both basins indicates that it is markedly enriched in coastal samples than offshore samples. The metal enrichment in zooplankton from the coastal areas of the eastern Arabian Sea occurs due to a combined effect of upwelling, riverine, and anthropogenic sources, whereas the latter two are only dominating in the coastal Bay of Bengal zooplankton. A comparison of average trace metal concentrations in the zooplankton from the Arabian Sea and Bay of Bengal showed that the enrichment of Fe, Zn, Cd, Ni, Cu, and Pb in the Bay of Bengal zooplankton may be due to high bioaccumulation factor of these elements, whereas the slight Co enrichment may be due to the bioavailability of this metal in the seawater.
Applied Ecology and Environmental Research, 2007
Trace metal contents in zooplankton samples were estimated as a part of Marine Research-Living Re... more Trace metal contents in zooplankton samples were estimated as a part of Marine Research-Living Resource Programme (MRLR) programme at 24 stations to establish the importance of these metals in the Bay of Bengal. The average concentration of Fe, Co, Ni, Cu, Zn, Cd and Pb in zooplankton from the Bay of Bengal indicates that it is slightly enriched in coastal samples than offshore samples. The heavy river discharge in the east coast of India might be related to the increased metal bioavailabilities in seawater and hence an increased uptake of metals by zooplankton from coastal areas than offshore areas. The zooplankton species examined showed great accumulations of metals, with bioaccumulation factors in the range >15,000 to 40,000,000 with respect to the concentrations (soluble fractions) in marine waters. Metal concentrations recorded in the Bay of Bengal zooplankton may be used as background levels for future studies, a body of water about which information is still very scarce.
Environmental Forensics, 2016
Environmental Earth Sciences, 2012
ABSTRACT Hydrography of the eastern Arabian Sea and associated chemical and biological responses ... more ABSTRACT Hydrography of the eastern Arabian Sea and associated chemical and biological responses were studied during the withdrawal phase of summer monsoon 2003. The shelf region off the southwest coast of India (10°N–15°N) continued to exhibit upwelling of colder (<28.5 °C), nutrient rich (nitrate >2.0 μM, phosphate >0.8 μM, silicate >4.0 μM) and relatively low oxygenated waters (~180 μM). The vertical advection of nutrients, coupled with anthropogenic terrestrial inputs, enhanced the levels of chlorophyll and primary productivity near the coastal margin off Cochin. The influence of both natural and anthropogenic nutrient loadings on the coastal system of the western continental shelf of India leads to eutrophication and hypoxia with negative impacts on the environment in general and fisheries in particular.
The Scientific World Journal, 2012
Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surf... more Concentrations and distributions of trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in surficial sediments of the Cochin backwaters were studied during both monsoon and pre-monsoon periods. Spatial variations were in accordance with textural charaterstics and organic matter content. A principal component analysis distinguished three zones with different metal accumulation capacity: (i) highest levels in north estuary, (ii) moderate levels in central zone, and (iii) lowest levels in southern part. Trace metal enrichments are mainly due to anthropogenic contribution of industrial, domestic, and agricultural effluents, whose effect is enhanced by settling of metals due to organic flocculation and inorganic precipitation associated with salinity changes. Enrichments factors using Fe as a normalizer showed that metal contamination was the product of anthropogenic activities. An assessment of degree of pollution-categorized sediments as moderately polluted with Cu and Pb, moderately...
Biogeosciences Discussions, 2010
Hydrographic characteristics of the southwest coast of India and its adjoining Cochin backwaters ... more Hydrographic characteristics of the southwest coast of India and its adjoining Cochin backwaters (CBW) were studied during the summer monsoon period. Anomalous formation of anoxia and denitrification were observed in the bottom layers of CBW, which have not been previously reported elsewhere in any tropical estuarine systems. The prevalent upwelling in the Arabian Sea (AS) brought cool, high saline, oxygen deficient and nutrient-rich waters towards the coastal zone and bottom layers of CBW during the high tide. High freshwater discharge in the surface layers brought high amount of nutrients and makes the CBW system highly productive. Intrusion of AS waters seems to be stronger towards the upstream end (∼15 km), than had been previously reported, as a consequence of the lowering of river discharges and deepening of channels in the estuary. Time series measurements in the lower reaches of CBW indicated a low mixing zone with increased stratification, 3 h after the high tide (highest high tide) and high variation in vertical mixing during the spring and neap phases. The upwelled waters (O 2 ≤ 40 µM) intruded into the estuary was found to lose more oxygen during the neap phase (suboxic O 2 ≤ 4 µM) than spring phase (hypoxic O 2 ≤ 10 µM). Increased stratification coupled with low ventilation and presence of high organic matter have resulted in an anoxic condition (O 2 = 0), 2-6 km away from barmouth of the estuary and leads to the formation of hydrogen sulphide. The reduction of nitrate and formation of nitrite within the oxygen deficient waters indicated strong denitrification intensity in the estuary. The expansion of oxygen deficient zone, denitrification and formation of hydrogen sulphide may lead to a destruction of biodiversity and an increase of green house gas emissions from this region.
Biogeosciences Discussions, 2010
The intensification of the natural coastal hypoxic zone over the western Indian shelf in the rece... more The intensification of the natural coastal hypoxic zone over the western Indian shelf in the recent years and its impact on the biogeochemistry and marine life is a matter of concern. This study examines the influence of the seasonal oxygen deficiency on the phosphorus geochemistry of the surface sediments along the western continental shelf of India (WCSI). Speciation of phosphorus along with the geochemical characteristics (total organic carbon-TOC, total nitrogen-TN, and total phosphorus-TP) of the surface sediments and the hydrography of the western continental shelf of India (WCSI) were studied, during late summer monsoon (LSM) and spring intermonsoon (SIM). The hydrography of the WCSI revealed upwelling and associated seasonal oxygen deficiency with denitrifying suboxic conditions along the inner shelf and hypoxic conditions along the outer shelf. High concentrations of dissolved phosphate (PO 4) and dissolved Iron (Fe) were also observed in the subsurface water of the inner shelf during LSM. The shelf water of the WCSI was oligotrophic and oxygen rich during SIM. A latitudinal enrichment of TOC, TN and TP in the surface sediments was observed at 13-17 • N, along the WCSI during LSM, where seasonal suboxia was intense. Authigenic apatite bound phosphorus (P aut) was the major phosphorus species along the WCSI during LSM whereas detrital flourapatite bound phosphorus (P det) was the major species during SIM. Substantial depletion of reactive iron(III)-bound phosphorus (∆P Fe) was observed in the surface sediments of the WCSI during LSM which showed significant correlation with the enrichment of PO 4 (∆PO 4) in the overlying water during LSM compared to SIM. PO 4 diffusing into the water column from the sediments by reductive dissolution of P Fe probably leads to high dissolved PO 4 along the inner shelf water during LSM which agrees with the existing hypothesis. Hence, phosphorus geochemistry of the surface sediments plays a major role in the biogeochemical cycling of phosphorus during periods of seasonal oxygen deficiency along the WCSI. Similar studies carried out along the eastern continental shelf of India (ECSI), where any kind of seasonal oxygen deficiency has not been reported yet, showed an abundance of 6090
Journal of Coastal Research, 2008
Even though continental margins cover only about 7-9% of the world ocean area, they are important... more Even though continental margins cover only about 7-9% of the world ocean area, they are important sites for organic carbon accumulation and hence play a major role in biogeochemical carbon cycling. Surface sediments from the western and eastern continental shelves of India were studied for their total organic matter content and the labile constituents such as total carbohydrates and proteins to get a better understanding of the hydrological and biogeochemical differences of the two regions on the nature of organic matter reaching the surface sediments. The sampling along the west coast was done during September-October 2003, when upwelling signatures were found to be still persisting along the shelf as evidenced by the low-oxygenated, nutrient-rich surface waters. The eastern shelf was sampled during November-December 2002. The shelf was found to be oxygen saturated and oligotrophic during the season. The surface sediments of the west coast contained a greater quantity of total organic matter when compared to the east coast, but the percentages of labile constituents of total organic matter in the sediments were found to be higher in the east coast by a factor of three as compared to the west coast. The differences in the productivity patterns and the hydrographical conditions were found to exert a major influence on the quantity and composition of organic matter in the surface sediments of the western and eastern continental shelves of India.
Environmental Monitoring and Assessment, 2013
Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".
Environmental Monitoring and Assessment, 2012
The distribution and accumulation of trace metals in the sediments of the Cochin estuary during t... more The distribution and accumulation of trace metals in the sediments of the Cochin estuary during the pre-monsoon, monsoon and post-monsoon periods were investigated. Sediment samples from 14 locations were collected and analysed for the metal contents (Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb), organic carbon, total nitrogen, total sulphur and grain size. The data were processed using statistical tools like correlation, factor and cluster analysis. The study revealed an enrichment of Cd and Zn in the study area particularly at station 2, which is confirmed by enrichment factor, contamination factor and geoaccumulation index. The factor analysis revealed that the source of Cd and Zn may be same. The study indicated that the spatial variation for the metals like Mg, Cr, Fe, Co, Ni, Cu, Zn, Cd and Pb were predominant unlike Mn which shows a temporal variation. The strong association of trace metals with Fe and Mn hydroxides and oxides are prominent along the Cochin estuary. The anthropogenic inputs of industrial effluents mainly control the trace metals enrichment in the Cochin estuary.
Environmental Monitoring and Assessment, 2012
Environmental Monitoring and Assessment, 2008