Assessment of heavy metal contamination in the surficial sediments from the lower Meghna River estuary,Noakhali coast,Bangladesh   总被引：1，自引：0，他引：1  

Mohammad Abdul Momin Siddique  Mahfuzur Rahman  Shahriar MdArifur Rahman  MdRubel Hassan  Zeenath Fardous  Muhammed Alamgir Zaman Chowdhury  Mohammad Belal Hossain 《国际泥沙研究》2021,36(3):384-391

Sediment samples were collected from ten selected sites of the lower Meghna River estuary,and six heavy metals were analyzed with Atomic Absorption Spectrophotometry(AAS)to assess the contamination level and the metals’association with sediment grain size.The current results revealed that the mean concentrations of the studied metals were ranked in descending order of iron(Fe)(1.29×103 mg/kg)>zinc(Zn)(42.41 mg/kg)>lead(Pb)(12.48 mg/kg)>chromium(Cr)(10.59 mg/kg)>copper(Cu)(6.22 mg/kg)>cadmium(Cd)(0.28 mg/kg).The geo-accumulation,contamination,and pollution load indexes suggested that the lower Meghna river estuary was not contaminated by Fe,Zn,Pb,Cr,and Cu.The mean size of the sediment ranged from 28.92 to 126.2 mm,and the Pearson correlation coefficient showed a significant association between Fe and Pb(coefficient of determination,r2=0.836;p<0.05),and no significant correlation was found between individual metals and grain size,indicating no or low influence on the metals distribution.  相似文献   

Seasonal flooding in Bangladesh – variability and predictability     

Md. Rashed Chowdhury  M. Neil Ward 《水文研究》2007,21(3):335-347

At present, Bangladesh has a flood forecasting lead time of only 3 days or so. There is demand for a forecasting lead time of a month to a season. The primary objectives of this paper are to study the variability and predictability of seasonal flooding in Bangladesh, as revealed by large‐scale predictors of the climate across the watersheds. To explore the source of predictability, accessible Bangladesh hydrological indicators are related to large‐scale oceanic variability and to large‐scale atmospheric circulation patterns predicted by general circulation models (GCMs). Correlation analyses between the flood‐affected area (FAA) for July–September and tropical sea‐surface temperature (SST) indicate connections to tropical Pacific and Indian Ocean SSTs, at a short lead time of a month or so. These are related to El Niño–southern oscillation (ENSO). Correlations between the SSTs of the preceding October–December and the July–September FAA are weaker but notable. Forecasts of the FAA using the leading principal components (PCs) of SST were made, which provided good skill with a lead time of a month or so. The streamflows and rainfall observed in Bangladesh have been added to these prediction models. Finally, the SST PCs were replaced with PCs of GCM prediction fields (precipitation). The prediction models at short lead time that were constructed for FAA were of generally similar levels of skill to that for SST. This is encouraging, as it suggests that linkages with SST can be successfully recovered in a physical model of the climate system in Bangladesh. This study concludes that seasonal flood prediction in Bangladesh is possible from the unusually warm or cold SST in parts of the tropics. This predictability can be enhanced with the information achievable from monitoring the downstream streamflows (which are generated mainly from upstream rainfall conditions) in advance of the flooding season. Finally, this study recommends formalizing a regional cooperation among the countries in the principal co‐basin areas of the Ganges–Brahmaputra–Meghna to achieve this goal. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Simulation of extreme rainfall and projection of future changes using the GLIMCLIM model     

Rashid  Md. Mamunur  Beecham  Simon  Chowdhury  Rezaul Kabir 《Theoretical and Applied Climatology》2017,130(1-2):453-466

Theoretical and Applied Climatology - In this study, the performance of the Generalized LInear Modelling of daily CLImate sequence (GLIMCLIM) statistical downscaling model was assessed to simulate...  相似文献   

Probing for suitable climatology to estimate the predictability of monsoon onset over Kerala (MOK), India     

J.?Pal  S.?ChaudhuriEmail author  S.?Mukherjee  A.?Roy?Chowdhury 《Theoretical and Applied Climatology》2017,129(1-2):59-76

Inter-annual variability in the onset of monsoon over Kerala (MOK), India, is investigated using daily temperature; mean sea level pressure; winds at 850, 500 and 200 hPa pressure levels; outgoing longwave radiation (OLR); sea surface temperature (SST) and vertically integrated moisture content anomaly with 32 years (1981–2013) observation. The MOK is classified as early, delayed, or normal by considering the mean monsoon onset date over Kerala to be the 1st of June with a standard deviation of 8 days. The objective of the study is to identify the synoptic setup during MOK and comparison with climatology to estimate the predictability of the onset type (early, normal, or delayed) with 5, 10, and 15 days lead time. The study reveals that an enhanced convection observed over the Bay of Bengal during early MOK is found to shift over the Arabian Sea during delayed MOK. An intense high-pressure zone observed over the western south Indian Ocean during early MOK shifts to the east during delayed MOK. Higher tropospheric temperature (TT) over the western Equatorial Ocean during early MOK and lower TT over the Indian subcontinent intensify the land–ocean thermal contrast that leads to early MOK. The sea surface temperature (SST) over the Arabian Sea is observed to be warmer during delayed than early MOK. During early MOK, the source of 850 hPa southwesterly wind shifts to the west equatorial zone while a COL region has been found during delayed MOK at that level. The study further reveals that the wind speed anomaly at the 200-hPa pressure level coincides inversely with the anomaly of tropospheric temperature.  相似文献   

First Record of <Emphasis Type="Italic">Porpita porpita</Emphasis> (Cnidaria: Hydrozoa) from the coral reef ecosystem,Bangladesh     

M. Shah Nawaz Chowdhury  S. M. Sharifuzzaman  Sayedur Rahman Chowdhury  Md. Rashed-Un-Nabi  M. Shahadat Hossain 《Ocean Science Journal》2016,51(2):293-297

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Farmer-level adaptation to climate change and agricultural drought: empirical evidences from the Barind region of Bangladesh     

Md. Nazir Hossain  Swapna Chowdhury  Shitangsu Kumar Paul 《Natural Hazards》2016,83(2):1007-1026

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Implementation of Sugeno: ANFIS for forecasting the seismic moment of large earthquakes over Indo-Himalayan region     

Sutapa Chaudhuri  Arumita Roy Chowdhury  Payel Das 《Natural Hazards》2018,90(1):391-405

The earthquake is known to be an unpredictable geophysical phenomenon. Only few seismic indicators and assumptions of earthquakes can be predicted with probable certainty. This study attempts to analyze the earthquakes over the Indo-Himalayan Border region including Bhutan, Bangladesh, Nepal, China and India during the period from 1995 to 2015. Bangladesh, Bhutan and China borders experience fewer earthquakes than Nepal and India border regions. However, Indo-China rim has inconsistency and vast range in its magnitude. Bangladesh though is a small country with respect to others, but it experiences earthquakes comparable to Bhutan. Nepal experiences highest number of earthquakes. In the last 20 years around 800 records have been observed with moment magnitude > 4.0 Richter scale, while very few records (around 10–12) have been observed for large earthquakes having moment magnitude > 6.0 Richter scale over the region. In this study adaptive neuro-fuzzy inference system has been implemented to assess the predictability of seismic moment associated with large earthquakes having the moment magnitude between 6.0 and 8.0 Richter scales using different combination of epochs, technique and membership functions. The Gaussian membership function with hybrid technique and 40 epochs is observed to be the reasonable model on the basis of the selected spatial and temporal scale. The forecast error in terms of root-mean-square error with the stopping criterion 0.001 has been observed to be 0.006 in case of large earthquakes (> 6.5 Richter scale), that is, forecast accuracy of 99.4%. The model bias of 0.6% may be due to inadequate number of large earthquakes having moment magnitude > 6.5 Richter scale over the region.  相似文献   

Characterization of hydrogeochemical process and evaluation of water quality of seven geothermal springs,Bakreswar, India     

Subhajit Roy  Balwant Kumar  Abbhijit Chowdhury  Umesh Kumar Singh  Samit Ray 《Arabian Journal of Geosciences》2018,11(12):314

A study was conducted in seven geothermal springs located in Bakreswar, District Birbhum, West Bengal, India, in order to assess numerous geochemical processes which were responsible for chemical composition of thermal and mineralized water. The study area lies over the Sone, Narmada, and Tapti lineament of Precambrian Chotanagpur Gneissic Complex. Water chemistry has been carried out based on reaction stoichiometry and geo-statistical tools to identify geochemical process. Piper and Gibbs diagram suggest that the spring water belongs to Ca²⁺-Mg²⁺-HCO₃^??+?CO₃^2? water type and are controlled by rock dominance. Dissolution and precipitation of calcite, dolomite, gypsum, and fluorite minerals were identified as principle source of major ions in seven geothermal spring water. Principle component analyses revealed that major ions of spring water are derived from geogenic processes such as weathering, dissolution, and precipitation of various minerals. Overall results suggest that major ions of the spring’s water are derived from natural origin because no evidence of anthropogenic sources was observed during the study period. This study has also revealed that water quality of spring’s water is not suitable for drinking purposes and quite suitable for irrigation because of high abundance of Na⁺, K⁺, Cl^?, and HCO₃^? ions.  相似文献   

PATTERNS AND CHANGES IN REGIONAL EMPLOYMENT STRUCTURE IN BANGLADESH     

Chowdhury Emdadul Haque  M.A. 《Singapore journal of tropical geography》1983,4(2):119-130

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Delineation of Ground Water Flow in Fractured Rock in the Southwestern Part of Manhattan, New York, Through Use of Advanced Borehole Geophysical Methods     

Frederick Stumm  Shafiul Chowdhury 《Ground Water Monitoring & Remediation》2003,23(3):42-49

Advanced borehole-geophysical methods were used to assess the geohydrology of fractured crystalline bedrock at five test boreholes in southwestern Manhattan Island, New York, in preparation for construction of a third water tunnel for New York City. The boreholes penetrated gneiss and other crystalline bedrock that has an overall southwest to northwest dipping foliation with a 60° dip. Most of the fractures encountered are either nearly horizontal or have moderate northwest dip azimuths. Fracture indexes range from 0.25 to 0.44 fracture per foot (0.3 m) of borehole.
Electromagnetic (EM) and heat-pulse flowmeter logs obtained under ambient and pumping conditions, together with other geophysical logs, indicate transmissive fracture zones in each borehole. Pumping tests of each borehole indicated transmissivity ranges from <2 to 360 ft²/day (0.2 to 33 m²/day). Ground water appears to flow within an interconnected fracture network toward the south and west within the study area. No correlation was indicated between the fracture index and the total borehole transmissivity.  相似文献