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Mukherjee A.,University of Texas at Austin | Fryar A.E.,University of Kentucky | Scanlon B.R.,University of Texas at Austin | Bhattacharya P.,KTH Royal Institute of Technology | Bhattacharya A.,Public Health Engineering Directorate
Applied Geochemistry | Year: 2011

The deeper groundwater (depending on definition) of the Bengal basin (Ganges-Brahmaputra delta) has long been considered as an alternate, safe drinking-water source in areas with As-enrichment in near-surface groundwater. The present study provides the first collective discussion on extent and controls of elevated As in deeper groundwater of a regional study area in the western part of the Bengal basin. Deeper groundwater is defined here as non-brackish, potable (Cl-≤250mg/L) groundwater available at the maximum accessed depth (∼80-300m). The extent of elevated As in deeper groundwater in the study area seems to be largely controlled by the aquifer-aquitard framework. Arsenic-enriched deeper groundwater is mostly encountered north of 22.75°N latitude, where an unconfined to semi-confined aquifer consisting of Holocene- to early Neogene-age gray sand dominates the hydrostratigraphy to 300m depth below land surface. Aquifer sediments are not abnormally enriched in As at any depth, but sediment and water chemistry are conducive to As mobilization in both shallow and deeper parts of the aquifer(s). The biogeochemical triggers are influenced by complex redox disequilibria. Results of numerical modeling and profiles of environmental tracers at a local-scale study site suggest that deeper groundwater abstraction can draw As-enriched water to 150m depth within a few decades, synchronous with the advent of wide-scale irrigational pumping in West Bengal (India). © 2011 Elsevier Ltd.

Mukherjee A.,Indian Institute of Technology Kharagpur | Fryar A.E.,University of Kentucky | Scanlon B.R.,University of Texas at Austin | Bhattacharya P.,KTH Royal Institute of Technology | And 2 more authors.
Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment | Year: 2012

Availability of safe drinking water is a major concern in the delta plains of the major Himalayan-Tibetan rivers in southern and southeastern Asia. While indiscriminate use of rivers and other surface water bodies for disposal of sewage and industrial waste has rendered them non-potable, natural, non-point source, elevated Arsenic (As) concentrations in groundwater exceeding the World Health Organization's (WHO) guideline value for drinking water of 0.01 mg/L have put millions of people at risk. Hence, finding an alternate, suitable and sustainable drinking-water source has been a priority in these areas. Generally, higher concentrations of dissolved As are found in groundwater of shallower aquifers and several studies have advocated deeper aquifers as a possible safe substitute. Using a composite hydro-geological approach, we demonstrate that regional-scale deeper groundwater As contamination in the western Bengal basin is dependent on the aquifer-aquitard framework and complex redox processes with partial equilibrium under natural flow conditions. Widespread deep irrigation pumping may be drawing shallower, contaminated groundwater down to greater depths. These findings have severe implications on finding alternate drinking water sources, in West Bengal, and adjoining areas of Bangladesh, with plausible similar geological and hydrogeological framework. © 2012 Taylor & Francis Group.

Thakur B.,Meghnad Saha Institute of Technology | Chakraborty S.,West Health Institute | Chakraborty S.,Public Health Engineering Directorate | Debsarkar A.,Jadavpur University | And 2 more authors.
Atmosfera | Year: 2010

Fireworks display during festive celebrations can cause acute short term air pollution. Deepawali -the festival of light- is celebrated in India, every year during October or November with great fireworks display. Concentration of air pollutants such as SPM (suspended particulate matter), PM10, PM2.5, SO2 and NO2 were monitored for six consecutive days during Deepawali in Salkia, a densely populated residential area near Kolkata, India, for assessing the impacts of fireworks on ambient air quality. The pollutant concentrations as recorded on Deepawali were found to be several times higher (6.44 times for SPM, 7.16 times for PM10, 5.35 times for PM2.5, 1.73 times for SO2 and 1.27 times for NO2) compared to a typical winter day value. The results indicated the huge contribution of fireworks on the pollutant levels. The particulate concentrations on Deepawali exceeded its respective 24 hour residential standards by several times (11.6 times for SPM, 22.3 times for PM10, and 34.3 times for PM2.5). Concentrations of metals like Ba, Cu, Cd, Pb, Hg, Al in collected PM2.5 were found to be increased by many times on Deepawali (56.72, 79.00, 16.67, 14.86, 12.00 and 6.26 times, respectively) compared to the previous day. The probable health impact of this huge though short-lived deterioration of the ambient air quality is estimated through Monte Carlo's simulation in terms of increase in relative risk of mortality and morbidity in exposed individuals and found to be extremely high. It suggests some controls on fireworks during festive celebrations.

Chowdhury P.R.,Public Health Engineering Directorate
Journal of Structural Engineering (India) | Year: 2014

During strong earthquakes submerged fine sandy layers may be subjected to liquefaction. BIS code IS-1893 recommends that the lateral resistance of liquefiable layers may be neglected. Use of deep foundation may be made to carry the load of the superstructure to non-liquefiable soil layers of superior bearing power. However as liquefiable layers offer no lateral resistance after liquefaction, the load carrying capacity of pile due to skin friction of liquefiable layers may be totally lost causing large settlement to the superstructure. If the depth of liquefiable layer is quiet large, due to loss of lateral resistance of liquefiable layer the unsupported length of pile may be of significant value, resulting in buckling of pile foundation under simultaneously acting axial and lateral seismic load. In this paper an attempt has been made to design an R.C.C bored cast-in-situ pile considering liquefaction of soil and buckling under lateral load as per existing provision of Indian standards, necessary comparison with unliquefied condition has also been attempted to indicate the extra sectional and reinforcement requirement for sustaining the superstructure against adverse settlement and tilting in the event of a strong motion earthquake inducing liquefaction.

RoyChowdhury P.,Public Health Engineering Directorate
Journal of the Institution of Engineers (India): Civil Engineering Division | Year: 2010

Elevated watertanks are inverted pendulum category of structure. Such type of structures are particularly vulnerable to the effects of lateral forces like wind and earthquake, as because they are top heavy structures, and hence lateral thrust caused by lateral forces like wind and earthquake has a tendency to topple such structures. Nowadays, from architectural consideration, elevated watertanks with shaft type of staging are more preferred, than frame type of staging. In this paper, an attempt has been made to study a oarticularcase of elevated water tank with shan type of staging system under various types of lateral forces like wind and earthquakes.

Chowdhury P.R.,Public Health Engineering Directorate
Journal of Structural Engineering (India) | Year: 2014

Elevated water tanks are important structures and are integral parts of municipal water supply projects. Such structures should be designed against exigencies such as terrorist attack with incendiary bombs and high explosives. Explosion with high explosives causes impulse loading on structures. In this paper, an attempt is made to model an elevated water tank as a SDOF system subjected to triangular impulse loading due to blast. The susceptibility of the R.C shaft staging towards buckling due to blast load is also studied.

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