| 11. |
- Neidhardt, H., et al.
(author)
-
Reconstructing the sedimentation history of the Bengal Delta Plain by means of geochemical and stable isotopic data
- 2013
-
In: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 36, s. 70-82
-
Journal article (peer-reviewed)abstract
- The purpose of this study is to examine the sedimentation history of the central floodplain area of the Bengal Delta Plain in West Bengal, India. Sediments from two boreholes were analyzed regarding lithology, geochemistry and the stable isotopic composition of embedded organic matter. Different lithofacies were distinguished that reflect frequent changes in the prevailing sedimentary depositional environment of the study area. The lowest facies comprises poorly sorted fluvial sediments composed of fine gravel to clay pointing at high transport energy and intense relocation processes. This facies is considered to belong to an early Holocene lowstand systems tract that followed the last glacial maximum. Fine to medium sands above it mark a gradual change towards a transgressive systems tract. Upwards increasing proportions of silt and the stable isotopic composition of embedded organic matter both indicate a gradual change from fluvial channel infill sediments towards more estuarine and marine influenced deposits. Youngest sediments are composed of clayey and silty overbank deposits of the Hooghly River that have formed a vast low-relief delta-floodplain. Close to the surface, small concretions of secondary Mn-oxides and Fe-(oxyhydr) oxides occur and mark the fluctuation range of the unsaturated zone. These concretions are accompanied by relatively high contents of trace elements such as Zn, Ni, Cu, and As. To sum up, the outcomes of this study provide new insights into the complex sedimentation history of the barely investigated central floodplain area of West Bengal.
|
|
| 12. |
- Ohmer, Christopher J., et al.
(author)
-
XFEL serial crystallography reveals the room temperature structure of methyl-coenzyme M reductase
- 2022
-
In: Journal of Inorganic Biochemistry. - : Elsevier BV. - 0162-0134 .- 1873-3344. ; 230, s. 111768-
-
Journal article (peer-reviewed)abstract
- Methyl-Coenzyme M Reductase (MCR) catalyzes the biosynthesis of methane in methanogenic archaea, using a catalytic Ni-centered Cofactor F430 in its active site. It also catalyzes the reverse reaction, that is, the anaerobic activation and oxidation, including the cleavage of the C-H bond in methane. Because methanogenesis is the major source of methane on earth, understanding the reaction mechanism of this enzyme can have massive implications in global energy balances. While recent publications have proposed a radical-based catalytic mechanism as well as novel sulfonate-based binding modes of MCR for its native substrates, the structure of the active state of MCR, as well as a complete characterization of the reaction, remain elusive. Previous attempts to structurally characterize the active MCR-Ni(I) state have been unsuccessful due to oxidation of the redox- sensitive catalytic Ni center. Further, while many cryo structures of the inactive Ni(II)-enzyme in various substrates bound forms have been published, no room temperature structures have been reported, and the structure and mechanism of MCR under physiologically relevant conditions is not known. In this study, we report the first room temperature structure of the MCRred1-silent Ni(II) form using an X-ray Free-Electron Laser (XFEL), with simultaneous X-ray Emission Spectroscopy (XES) and X-ray Diffraction (XRD) data collection. In celebration of the seminal contributions of inorganic chemist Dick Holm to our understanding of nickel-based catalysis, we are honored to announce our findings in this special issue dedicated to this remarkable pioneer of bioinorganic chemistry.
|
|
| 13. |
- Bhattacharya, Prosun, 1962-, et al.
(author)
-
Tubewell platform color : Assessment of a tool for rapid screening of arsenic and manganese in well water
- 2012
-
In: UNDERSTANDING THE GEOLOGICAL AND MEDICAL INTERFACE OF ARSENIC, AS 2012. - : CRC PRESS-TAYLOR & FRANCIS GROUP. ; , s. 515-518
-
Conference paper (peer-reviewed)abstract
- This study attempts to make a statistical comparison between Tubewell (TW) platform color and the level of Arsenic (As) and Manganese (Mn) concentration in groundwater abstracted from a set of 423 Tubewells (TWs) in Chakdaha Block of Nadia District, West Bengal, India to validate platform color as a screening tool for both As and Mn in groundwater. The results indicate that water extracted from TWs with black colored platform in 93% cases was safe for As while water extracted from TWs with red colored platform is contaminated with As with 38% certainty, compared to drinking water standard of India (50 mu g/L). At this standard the respective efficiency, sensitivity and specificity of the tool are 65, 85 and 59%. If WHO drinking water guideline (10 mu g/L) is considered, the certainty increases to 73% and 84% respectively for black and red colored platform with respective efficiency, sensitivity and specificity values of 79, 77 and 81%. Furthermore, the black colored platform with 78% certainty indicates well water is enriched with Manganese (Mn), while red colored platform indicates water is low in Mn with 64% certainty evaluated against Indian national standard of 300 mu g/L. This study demonstrates that platform color can be potentially used as an initial screening tool for As and Mn, to assess the safe water acess for drinking purposes.
|
|
| 14. |
- Bhowmick, S., et al.
(author)
-
Groundwater arsenic chemistry and redox process comparison in three physiographic settings of deltaic West Bengal, India
- 2012
-
In: Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment. - : CRC Press. - 9780415637633 ; , s. 54-56
-
Conference paper (peer-reviewed)abstract
- A comparative hydrogeochemical study was carried out in West Bengal covering three physiographic settings of deltaic floodplains to demonstrate the control of geogenic and anthropogenic influences on groundwater arsenic (As) mobilization. The low redox potential (Eh = -185 to -86 mV) and the presence of low sulfate (SO 4 2-) and high Dissolved Organic Carbon (DOC), phosphate (PO 4 3-) and bicarbonate) (HCO 3 -) concentrations in groundwater signifies microbially mediated redox processes controlling As release in the aquifer. The release of As is influenced by both geogenic (i.e. geomorphology and/or landform features) and anthropogenic (i.e. unsewered sanitation and domestic wastes) factors.
|
|
| 15. |
- Biswas, Ashis, et al.
(author)
-
Potentiality of shallow brown sand aquifers as an alternative safe drinking water source in Bengal Basin
- 2012
-
In: Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment. - 9780415637633 ; , s. 67-68
-
Conference paper (peer-reviewed)abstract
- The present study investigated the regional distribution of brown sand aquifers (BSA) as well as their hydrogeochemical contrast to grey sand aquifers (GSA). The data indicated that in BSA redox status is limited to the Mn oxides reduction stage, while in GSA, Fe oxides reduction to SO 4 2- reduction processes are prevalent. Though, the concentration of dissolved As was very low (<10 ÎŒg/L) in BSA, the concentration of Mn was very high (>400 ÎŒg/L). Whereas in GSA, the enrichment patterns of As and Mn were opposite to that of BSA. This study suggests that underlying health risk of Mn in drinking water needs to be addressed more rigorously before advocating for mass scale exploitation of BSA as an alternative drinking water source despite of significantly low As concentration in groundwater.
|
|
| 16. |
- Chatterjee, D., et al.
(author)
-
Arsenic in the bengal delta plain : Geochemical complications and potential mitigation option
- 2016
-
In: Arsenic Research and Global Sustainability - Proceedings of the 6th International Congress on Arsenic in the Environment, AS 2016. - : CRC Press/Balkema. - 9781138029415 ; , s. 47-49
-
Conference paper (peer-reviewed)abstract
- Groundwaters from the Bengal Delta Plain (BDP) are now significantly enriched with natural arsenic (As), frequently exceeding the WHO guideline value (10 μg/L). The contaminated ground-water is often derived from geologically young sediments (Holocene), low-lying areas and flat terrain where groundwater movement is slow (poorly flushed aquifers). The As content of the aquifer material is not regularly high (3–18 mg/kg), however, the groundwater As content is often exceptionally high (up to 3200 μg/L). The most notable feature of the tubewell groundwater is their predominantly reducing conditions at near-neutral pH values (6.5–7.5) with high redox sensitive species. The issue of deeper aquifer (safe and unsafe) is most challenging in terms of both geological and public health point of view. In this context, deeper aquifer is possibly the most reliable source where remediation technologies are in many cases incapable of yielding As-safe water.
|
|
| 17. |
- Halder, Dipti, et al.
(author)
-
Arsenic exposure and health risk from consumption of brown rice in rural Bengal, India
- 2012
-
In: Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment. - : Taylor & Francis Group. - 9780415637633 ; , s. 505-507
-
Conference paper (peer-reviewed)abstract
- This study investigates the Arsenic (As) concentration in different types of brown rice grain and assesses As exposure and non-cancer health risk from rice consumption. Daily Intake (DI rice) and Hazard Quotient (HQ) from rice were calculated for the people who are consuming these type of rice. Daily intake value of As from rice was compared with previous WHO recommended Provisional Tolerable Daily Intake value (PTDI) of 2.1 ÎŒg/day/kg bw to understand which kind of rice may pose potential health risk. Hazard quotient (HQ) was determined to understand the potential non-cancer health risk of the people who are consuming these rice. This study indicates that for SB brown rice consumer in 29% cases DI rice exceeds the previous PTDI value and 100% cases HQ value exceeds 1.
|
|
| 18. |
- Halder, Dipti, et al.
(author)
-
Assessment of arsenic exposure risk from drinking water and dietary component in West Bengal, India
- 2013
-
Conference paper (peer-reviewed)abstract
- The current status of arsenic (As) exposure risk from drinking water and different dietary components in rural Bengal has been compared in the present study. This study shows that the consumption of rice is the major source of dietary intake of inorganic As among the population when they are drinking As safe water. Consumption of vegetables does not pose a significant health threat to the population independently; it nevertheless can increase the total daily intake of inorganic As (TDI-iAs). The results indicate that when people are drinking water with As concentration <10 μg L-1, in 35% of the cases the total daily intake of inorganic As (TDI-iAs) exceeds the previous provisional tolerable daily intake (PTDI) value of 2.1 μg day-1 kg-1 BW, recommended by World Health Organization (WHO). It should be mention here that the joint FAO/WHO expert committee on food additives (JECFA) has withdrawn the previous PTDI value in their 72nd meeting because PTDI value was in the lower range of bench mark dose level for 0.5% increased of lung cancer. However, Codex Committee on Contaminants in Foods (CCCF) has argued that TDI-iAs below BMDL0.5 does not indicates that there is no risk and this motivated us to compare TDI-iAs of the participants with the previous PTDI value of 2.1 μg day-1 kg-1 bw. At the As concentration level <10 μg L-1in drinking water, the consumption of rice is the major source of daily intake of inorganic As. When As concentration in drinking water exceeds 10 μg L-1, drinking water and rice consumption contributes almost equally (~40% from rice, ~50% from drinking water, and 10% from vegetables according to median DI-iAs) and TDI-iAs exceeds previous PTDI for all the participants. The relative contribution of daily intake of iAs from drinking water (DI-iAs-DW) largely predominates over daily intake of iAs from rice (DI-iAs-R) when As concentration in drinking water exceeds 50 μg L-1. This study implies that when consumption of rice contributes significantly to the TDI-iAs, supply of drinking water to the population considering national drinking water standard of India and Bangladesh as a safety measure for As might compound the As exposure largely by increasing TDI-iAs. Thus it can be concluded that any effort to mitigate the As poisoning of rural villagers in Bengal must look beyond the drinking water and consider all the routes of exposure.
|
|
| 19. |
- Kumar, Manish, et al.
(author)
-
Lead time of early warning by wastewater surveillance for COVID-19 : Geographical variations and impacting factors
- 2022
-
In: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 441
-
Research review (peer-reviewed)abstract
- The global data on the temporal tracking of the COVID-19 through wastewater surveillance needs to be comparatively evaluated to generate a proper and precise understanding of the robustness, advantages, and sensitivity of the wastewater-based epidemiological (WBE) approach. We reviewed the current state of knowledge based on several scientific articles pertaining to temporal variations in COVID-19 cases captured via viral RNA predictions in wastewater. This paper primarily focuses on analyzing the WBE-based temporal variation reported globally to check if the reported early warning lead-time generated through environmental surveillance is pragmatic or latent. We have compiled the geographical variations reported as lead time in various WBE reports to strike a precise correlation between COVID-19 cases and genome copies detected through wastewater surveillance, with respect to the sampling dates, separately for WASH and non-WASH countries. We highlighted sampling methods, climatic and weather conditions that significantly affected the concentration of viral SARS-CoV-2 RNA detected in wastewater, and thus the lead time reported from the various climatic zones with diverse WASH situations were different. Our major findings are: i) WBE reports around the world are not comparable, especially in terms of gene copies detected, lag-time gained between monitored RNA peak and outbreak/peak of reported case, as well as per capita RNA concentrations; ii) Varying sanitation facility and climatic conditions that impact virus degradation rate are two major interfering features limiting the comparability of WBE results, and iii) WBE is better applicable to WASH countries having well-connected sewerage system.
|
|
| 20. |
- Kundu, A. K., et al.
(author)
-
Variation of arsenic in shallow aquifers of the Bengal Basin : Controlling geochemical processes
- 2016
-
In: Arsenic Research and Global Sustainability - Proceedings of the 6th International Congress on Arsenic in the Environment, AS 2016. - : CRC Press/Balkema. - 9781138029415 ; , s. 52-53
-
Conference paper (peer-reviewed)abstract
- The natural occurrence of high dissolved Arsenic (As) in groundwater is quiet common and has been reported from almost entire globe. Nevertheless the scale of problem is most severe in several countries of South and South East Asia, notably in BDP (Bengal Delta Plain). Different As release mechanism has been put forward to explain As enrichment in groundwater. The groundwater As distribution and their relationship with land-use pattern suggest that As release is influenced by local conditions (e.g. sanitation, presence of surface water, agricultural practice). High rate of groundwater withdrawl can accelerate As mobilization by enhancing the transport of degradable organic matter with recharge water from the surface.
|
|
