ABSTRACT Despite the greatest diversity of snakes being in the tropics, detailed ecological studi... more ABSTRACT Despite the greatest diversity of snakes being in the tropics, detailed ecological studies are rare, especially in tropical Asia. We studied the ecology of a coastal marine homalopsid (rear-fanged, aquatic snakes) assemblage in southeastern Bangladesh. Data were collected on community structure, resource partitioning (diet and habitat), body size and sexual size dimorphism. A total of 653 specimens belonging to three species were collected: Cerberus rynchops (81% of total capture), a medium-sized piscivorous snake, found to be the most abundant species in the study site followed by two crustacean eaters, Gerada prevostiana (13%) and Fordonia leucobalia (6%). The three species were relatively similar in terms of body size but were inconsistent with each other both in terms of morphological patterns and demography characteristics, with sex-ratio being equal in two species but female-biased in G. prevostiana. There was no apparent non-random resource partitioning along the microhabitat axis but a clear pattern of niche partitioning was observed along the food axis. Despite the very unusual evolutionary history of the Homalopsidae inside the group of the Colubroidea, our snake assemblage very closely resembled other communities of snakes worldwide.
Boreholes (50 m depth) and piezometers (50 m depth) were drilled and installed for collecting As-... more Boreholes (50 m depth) and piezometers (50 m depth) were drilled and installed for collecting As-rich sediments and groundwater in the Ganges, Brahmaputra, and Meghna flood plains for geochemical analyses. Forty-one groundwater samples were collected from the three areas for the analyses of cations (Ca(2+), Mg(2+), K(+), Na(+)), anions (Cl(-), NO(3)(-), SO(4)(2-)), total organic carbon (TOC), and trace elements (As, Mn, Fe, Sr, Se, Ni, Co, Cu, Mo, Sb, Pb). X-ray powder diffraction (XRD) and X-ray fluorescence (XRF) were performed to characterize the major mineral and chemical contents of aquifer sediments. In all three study areas, results of XRF analysis clearly show that fine-grained sediments contain higher amounts of trace element because of their high surface area for adsorption. Relative fluorescent intensity of humic substances in groundwater samples ranges from 30 to 102 (mean 58 ± 20, n = 20), 54-195 (mean 105 ± 48, n = 10), and 27-243 (mean 79 ± 71, n = 11) in the Ganges, Brahmaputra and Meghna flood plains, respectively. Arsenic concentration in groundwater (20-50 m of depth) ranges from 3 to 315 μg/L (mean 62.4 ± 93.1 μg/L, n = 20), 16.4-73.7 μg/L (mean 28.5 ± 22.4 μg/L, n = 10) and 4.6-215.4 μg/L (mean 30.7 ± 62.1 μg/L, n = 11) in the Ganges, Brahmaputra and Meghna flood plains, respectively. Specific ultra violet adsorption (SUVA) values (less than 3 m(-1) mg(-1) L) indicate that the groundwater in the Ganges flood plain has relatively low percentage of aromatic organic carbon compared to those in the Brahmaputra and Meghna flood plains. Arsenic content in sediments ranges from 1 to 11 mg/kg (mean 3.5 ± 2.7 mg/kg, n = 17) in the three flood plains. Total organic carbon content is 0.5-3.7 g/kg (mean 1.9 ± 1.1 g/kg) in the Ganges flood plain, 0.5-2.1 g/kg (mean: 1.1 ± 0.7 g/kg) in the Brahmaputra flood plain and 0.3-4.4 g/kg (mean 1.9 ± 1.9 g/kg) in the Meghna flood plain. Arsenic is positively correlated with TOC (R(2) = 0.50, 0.87, and 0.85) in sediments from the three areas. Fourier transform infrared (FT-IR) analysis of the sediments revealed that the functional groups of humic substances in three areas include amines, phenol, alkanes, and aromatic carbon. Arsenic and Fe speciation in sediments were determined using XANES and the results imply that As(V) and Fe(III) are the dominant species in most sediments. The results also imply that As (V) and Fe (III) in most of the sediment samples of the three areas are the dominant species. X-ray absorption fine structure (EXAFS) analysis shows that FeOOH is the main carrier of As in the sediments of three areas. In sediments, As is well correlated with Fe and Mn. However, there is no such correlation observed between As and Fe as well as As and Mn in groundwater, implying that mobilizations of Fe, Mn, and As are decoupled or their concentrations in groundwater have been affected by other geochemical processes following reductive dissolution of Fe or Mn-hydroxides. For example, dissolved Fe and Mn levels may be affected by precipitation of Fe- and Mn-carbonate minerals such as siderite, while liberated As remains in groundwater. The groundwaters of the Brahmaputra and Meghna flood plains contain higher humic substances in relative fluorescence intensity (or fluorescence index) and lower redox potential compared to the groundwater of Ganges flood plain. This leads to the release of arsenic and iron to groundwater of these three plains in considerable amounts, but their concentrations are distributed in spatial variations.
This study reveals that some trace metals were found in sediments of the Sitakund Upazilla of Chi... more This study reveals that some trace metals were found in sediments of the Sitakund Upazilla of Chittagong, Bangladesh, largely due to ship breaking activities in the area. This was seen when comparing levels of trace metals in the sediments of the study area with the recommended values of unpolluted sediments. Thus, it was inferred that the trace metal concentrations around the ship breaking area were higher than that of the control site, Sandwip, and near the Karnafully River mouth. The trace elements in the sediment samples were significantly correlated with one another. Enrichment factor values of the sediment samples revealed that most of the sediments were minor to severely enriched by trace metals. Sediments of three stations out of 11 stations of the study area were minor to moderately enriched by Cd metal. The geo-accumulation index (Igeo) values of the sediment samples revealed that the sediments of the ship breaking area were affected from slight to strong contamination with trace metals and sediments in two stations of the study area were affected moderately contaminated by Cd metal. Potential contamination indices of the sediment samples indicated that Cr, Zn, As, and Pb were the greatest contaminants.
Humic substances in groundwater and aquifer sediments from the arsenicosis and Blackfoot disease ... more Humic substances in groundwater and aquifer sediments from the arsenicosis and Blackfoot disease (BFD) affected areas in Bangladesh (Bengal delta plain) and Taiwan (Lanyang plain and Chianan plain) were characterized using fluorescence spectrophotometry and Fourier transform infrared (FT-IR) spectroscopy. The results demonstrate that the
JEAN, Jiin-Shuh 1, REZA, AHM Selim 1, LEE, Ming-Kuo 2, BUNDSCHUH, Jochen 1, and LIU, Chia-Chuan 1... more JEAN, Jiin-Shuh 1, REZA, AHM Selim 1, LEE, Ming-Kuo 2, BUNDSCHUH, Jochen 1, and LIU, Chia-Chuan 1,(1) Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan, 70101, Taiwan, jiinshuh@ mail. ncku. edu. tw,(2) Department of ...
ABSTRACT Despite the greatest diversity of snakes being in the tropics, detailed ecological studi... more ABSTRACT Despite the greatest diversity of snakes being in the tropics, detailed ecological studies are rare, especially in tropical Asia. We studied the ecology of a coastal marine homalopsid (rear-fanged, aquatic snakes) assemblage in southeastern Bangladesh. Data were collected on community structure, resource partitioning (diet and habitat), body size and sexual size dimorphism. A total of 653 specimens belonging to three species were collected: Cerberus rynchops (81% of total capture), a medium-sized piscivorous snake, found to be the most abundant species in the study site followed by two crustacean eaters, Gerada prevostiana (13%) and Fordonia leucobalia (6%). The three species were relatively similar in terms of body size but were inconsistent with each other both in terms of morphological patterns and demography characteristics, with sex-ratio being equal in two species but female-biased in G. prevostiana. There was no apparent non-random resource partitioning along the microhabitat axis but a clear pattern of niche partitioning was observed along the food axis. Despite the very unusual evolutionary history of the Homalopsidae inside the group of the Colubroidea, our snake assemblage very closely resembled other communities of snakes worldwide.
Boreholes (50 m depth) and piezometers (50 m depth) were drilled and installed for collecting As-... more Boreholes (50 m depth) and piezometers (50 m depth) were drilled and installed for collecting As-rich sediments and groundwater in the Ganges, Brahmaputra, and Meghna flood plains for geochemical analyses. Forty-one groundwater samples were collected from the three areas for the analyses of cations (Ca(2+), Mg(2+), K(+), Na(+)), anions (Cl(-), NO(3)(-), SO(4)(2-)), total organic carbon (TOC), and trace elements (As, Mn, Fe, Sr, Se, Ni, Co, Cu, Mo, Sb, Pb). X-ray powder diffraction (XRD) and X-ray fluorescence (XRF) were performed to characterize the major mineral and chemical contents of aquifer sediments. In all three study areas, results of XRF analysis clearly show that fine-grained sediments contain higher amounts of trace element because of their high surface area for adsorption. Relative fluorescent intensity of humic substances in groundwater samples ranges from 30 to 102 (mean 58 ± 20, n = 20), 54-195 (mean 105 ± 48, n = 10), and 27-243 (mean 79 ± 71, n = 11) in the Ganges, Brahmaputra and Meghna flood plains, respectively. Arsenic concentration in groundwater (20-50 m of depth) ranges from 3 to 315 μg/L (mean 62.4 ± 93.1 μg/L, n = 20), 16.4-73.7 μg/L (mean 28.5 ± 22.4 μg/L, n = 10) and 4.6-215.4 μg/L (mean 30.7 ± 62.1 μg/L, n = 11) in the Ganges, Brahmaputra and Meghna flood plains, respectively. Specific ultra violet adsorption (SUVA) values (less than 3 m(-1) mg(-1) L) indicate that the groundwater in the Ganges flood plain has relatively low percentage of aromatic organic carbon compared to those in the Brahmaputra and Meghna flood plains. Arsenic content in sediments ranges from 1 to 11 mg/kg (mean 3.5 ± 2.7 mg/kg, n = 17) in the three flood plains. Total organic carbon content is 0.5-3.7 g/kg (mean 1.9 ± 1.1 g/kg) in the Ganges flood plain, 0.5-2.1 g/kg (mean: 1.1 ± 0.7 g/kg) in the Brahmaputra flood plain and 0.3-4.4 g/kg (mean 1.9 ± 1.9 g/kg) in the Meghna flood plain. Arsenic is positively correlated with TOC (R(2) = 0.50, 0.87, and 0.85) in sediments from the three areas. Fourier transform infrared (FT-IR) analysis of the sediments revealed that the functional groups of humic substances in three areas include amines, phenol, alkanes, and aromatic carbon. Arsenic and Fe speciation in sediments were determined using XANES and the results imply that As(V) and Fe(III) are the dominant species in most sediments. The results also imply that As (V) and Fe (III) in most of the sediment samples of the three areas are the dominant species. X-ray absorption fine structure (EXAFS) analysis shows that FeOOH is the main carrier of As in the sediments of three areas. In sediments, As is well correlated with Fe and Mn. However, there is no such correlation observed between As and Fe as well as As and Mn in groundwater, implying that mobilizations of Fe, Mn, and As are decoupled or their concentrations in groundwater have been affected by other geochemical processes following reductive dissolution of Fe or Mn-hydroxides. For example, dissolved Fe and Mn levels may be affected by precipitation of Fe- and Mn-carbonate minerals such as siderite, while liberated As remains in groundwater. The groundwaters of the Brahmaputra and Meghna flood plains contain higher humic substances in relative fluorescence intensity (or fluorescence index) and lower redox potential compared to the groundwater of Ganges flood plain. This leads to the release of arsenic and iron to groundwater of these three plains in considerable amounts, but their concentrations are distributed in spatial variations.
This study reveals that some trace metals were found in sediments of the Sitakund Upazilla of Chi... more This study reveals that some trace metals were found in sediments of the Sitakund Upazilla of Chittagong, Bangladesh, largely due to ship breaking activities in the area. This was seen when comparing levels of trace metals in the sediments of the study area with the recommended values of unpolluted sediments. Thus, it was inferred that the trace metal concentrations around the ship breaking area were higher than that of the control site, Sandwip, and near the Karnafully River mouth. The trace elements in the sediment samples were significantly correlated with one another. Enrichment factor values of the sediment samples revealed that most of the sediments were minor to severely enriched by trace metals. Sediments of three stations out of 11 stations of the study area were minor to moderately enriched by Cd metal. The geo-accumulation index (Igeo) values of the sediment samples revealed that the sediments of the ship breaking area were affected from slight to strong contamination with trace metals and sediments in two stations of the study area were affected moderately contaminated by Cd metal. Potential contamination indices of the sediment samples indicated that Cr, Zn, As, and Pb were the greatest contaminants.
Humic substances in groundwater and aquifer sediments from the arsenicosis and Blackfoot disease ... more Humic substances in groundwater and aquifer sediments from the arsenicosis and Blackfoot disease (BFD) affected areas in Bangladesh (Bengal delta plain) and Taiwan (Lanyang plain and Chianan plain) were characterized using fluorescence spectrophotometry and Fourier transform infrared (FT-IR) spectroscopy. The results demonstrate that the
JEAN, Jiin-Shuh 1, REZA, AHM Selim 1, LEE, Ming-Kuo 2, BUNDSCHUH, Jochen 1, and LIU, Chia-Chuan 1... more JEAN, Jiin-Shuh 1, REZA, AHM Selim 1, LEE, Ming-Kuo 2, BUNDSCHUH, Jochen 1, and LIU, Chia-Chuan 1,(1) Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan, 70101, Taiwan, jiinshuh@ mail. ncku. edu. tw,(2) Department of ...
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