Linking IPCC AR4 & AR5 frameworks for assessing vulnerability and risk to climate change in the Indian Bengal Delta

The International Panel on Climate Change (IPCC) AR5 (Fifth Assessment Report, 2014) conceptual approach and terminology is aligned with a concept of risk which differs from the previous framework (AR4). This study draws links between the AR5 concept of risk with the previous concept of vulnerability (AR4). The most significant difference between the results of the AR4 and AR5 approaches is the change in sub-district level relative rankings. Findings show that Basanti, in the Bengal Delta, is the most vulnerable sub-district using the AR4 approach, whereas Gosaba is found to be highly exposed to risk using the AR5 approach.UK Government's Department for International Development (DFID

Assessment and attribution of mangrove forest changes in the Indian Sundarbans from 2000 to 2020

The Indian Sundarbans, together with Bangladesh, comprise the largest mangrove forest in the world. Reclamation of the mangroves in this region ceased in the 1930s. However, they are still subject to adverse environmental influences, such as sediment starvation due to migration of the main river channels in the Ganges–Brahmaputra delta over the last few centuries, cyclone landfall, wave action from the Bay of Bengal—changing hydrology due to upstream water diversion—and the pervasive effects of relative sea-level rise. This study builds on earlier work to assess changes from 2000 to 2020 in mangrove extent, genus composition, and mangrove ‘health’ indicators, using various vegetation indices derived from Landsat and MODIS satellite imagery by performing maximum likelihood supervised classification. We show that about 110 km 2 of mangroves disappeared within the reserve forest due to erosion, and 81 km 2 were gained within the inhabited part of Sundarbans Biosphere Reserve (SBR) through plantation and regeneration. The gains are all outside the contiguous mangroves. However, they partially compensate for the losses of the contiguous mangroves in terms of carbon. Genus composition, analyzed by amalgamating data from published literature and ground-truthing surveys, shows change towards more salt-tolerant genus accompanied by a reduction in the prevalence of freshwater-loving Heiritiera, Nypa, and Sonneratia assemblages. Health indicators, such as the enhanced vegetation index (EVI) and normalized differential vegetation index (NDVI), show a monotonic trend of deterioration over the last two decades, which is more pronounced in the sea-facing parts of the mangrove forests. An increase in salinity, a temperature rise, and rainfall reduction in the pre-monsoon and the post-monsoon periods appear to have led to such degradation. Collectively, these results show a decline in mangrove area and health, which poses an existential threat to the Indian Sundarbans in the long term, especially under scenarios of climate change and sea-level rise. Given its unique values, the policy process should acknowledge and address these threats

Diarrhoeal health risks attributable to water-borne-pathogens in arsenic-mitigated drinking water in West Bengal are largely independent of the microbiological quality of the supplied water

Abstract: There is a growing discussion about the possibility of arsenic mitigation measures in Bengal and similar areas leading to undesirable substitution of water-borne-pathogen attributable risks pathogens for risks attributable to arsenic, in part because of uncertainties in relative pathogen concentrations in supplied and end-use water. We try to resolve this discussion, by assessing the relative contributions of water supply and end-user practices to water-borne-pathogen-attributable risks for arsenic mitigation options in a groundwater arsenic impacted area of West Bengal. Paired supplied arsenic-mitigated water and end-use drinking water samples from 102 households were collected and analyzed for arsenic and thermally tolerant coliforms [TTC], used as a proxy for microbiological water quality, We then estimated the DALYs related to key sequelae, diarrheal diseases and cancers, arising from water-borne pathogens and arsenic respectively. We found [TTC] in end-use drinking water to depend only weakly on [TTC] in source-water. End-user practices far outweighed the microbiological quality of supplied water in determining diarrheal disease burden. [TTC] in source water was calculated to contribute <1% of total diarrheal disease burden. No substantial demonstrable pathogen-for-arsenic risk substitution attributable to specific arsenic mitigation of supplied waters was observed, illustrating the benefits of arsenic mitigation measures in the area studied

Exploratory modelling of the impacts of sea-level rise on the Sundarbans mangrove forest, West Bengal, India

In this paper we conduct exploratory simulations of the possible evolution of the Indian Sundarbans mangroves to 2100 under a range of future sea-level rise (SLR) scenarios, considering the effects of both inundation and shoreline erosion. The Sea Level Affecting Marshes Model (SLAMM) is used to simulate habitat transitions due to inundation and these outputs are combined with an empirical model of SLR-driven shoreline erosion. A set of plausible climate-induced SLR scenarios are considered, together with delta subsidence and constrained vertical sediment accretion. Significant mangrove decline is found in all cases: the greater the rise in sea level the greater the losses. By the end of the century, the Indian Sundarbans mangroves could lose between 42 % and 80 % of their current area if current management is continued. Managed realignment could offset these losses but at the expense of productive land and the migration of the human population

Exploratory modelling of the impacts of sea-level rise on the Sundarbans mangrove forest, West Bengal, India

In this paper we conduct exploratory simulations of the possible evolution of the Indian Sundarbans mangroves to 2100 under a range of future sea-level rise (SLR) scenarios, considering the effects of both inundation and shoreline erosion. The Sea Level Affecting Marshes Model (SLAMM) is used to simulate habitat transitions due to inundation and these outputs are combined with an empirical model of SLR-driven shoreline erosion. A set of plausible climate-induced SLR scenarios are considered, together with delta subsidence and constrained vertical sediment accretion. Significant mangrove decline is found in all cases: the greater the rise in sea level the greater the losses. By the end of the century, the Indian Sundarbans mangroves could lose between 42 % and 80 % of their current area if current management is continued. Managed realignment could offset these losses but at the expense of productive land and the migration of the human population

Influence of para substituents in controlling photophysical behavior and different non-covalent weak interactions in zinc complexes of a phenol based "end-off" compartmental ligand

Three dinuclear zinc(II) complexes with "end-off" compartmental ligands, namely 2,6-bis(N-ethylmorpholine-iminomethyl)-4-R-phenol (I: R = -CH3, Cl, tBu) were synthesized with the aim of exploring the role of the para substituent present in the ligand backbone in controlling the structural diversity, photophys. properties and different weak interactions of the complexes. The complexes are [Zn2L1(CH3CO2)2]1/2[Zn(NCS)4].3/2H2O (1), [Zn2L2(CH3CO2)2]1/2[Zn(NCS)4] (2), and [Zn2L3(CH3CO2)2]1/2[Zn(NCS)4] (3),. All three species, with the general formula 2[Zn2L(CH3COO)2][Zn(NCS)4], show the complex anion Zn(NCS)42- as a common structural feature decisive for crystn. All of them possess several noncovalent weak interactions where the nature of the "R'' group plays an essential role as exposed by DFT study. Besides exhibiting fluorescence behavior, the complexes also show para substitution controlled phosphorescence both at room and low temp. Anisotropy studies suggest the existence of complexes 2 and 3 as dimers in soln. The origins of the unusual room temp. phosphorescence and fluorescence behavior of the complexes were rationalized in the light of theor. calcns. [on SciFinder(R)

Combined Experimental and Theoretical Investigation on Ligand and Anion Controlled Complex Formation with Unprecedented Structural Features and Photoluminescence Property of Zinc(II) Complexes

[eng] By using two potential tridentate ligands, HL1 [4- chloro-2-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol] and HL2 [4-chloro-2-[(3-morpholin-4-yl-propylimino)-methyl]-phenol], which differ by one methylene group in the alkyl chain, four new ZnII complexes, namely, [Zn(L2H)2](ClO4)2 (1), [Zn(L1)(H2O)2][Zn(L1)(SCN)2] (2), [Zn(L1)(dca)]n (3), and [Zn2(L1)2(N3)2(H2O)2] (4) [where dca = dicyanamide anion] were synthesized and structurally characterized. The results indicate that the slight structural difference between the ligands, HL1 and HL2, because of the one methylene group connecting the nitrogen atoms provokes a chemical behavior completely different from what was expected. Any attempt to isolate the Zn(L2) complexes with thiocyanato, dicyanamido, and azide was unsuccessful, and perchlorate complex 1 was always obtained. In contrast, with HL1 we obtained structural diversity on varying the anions, but we failed to isolate the analogous perchlorate complex of HL1. Single-crystal X-ray analyses revealed that the morpholine nitrogen of ligand L2 is protonated and thus does not take part in coordination with ZnII in complex 1. On the other hand, the morpholine nitrogen of L1 is coordinated to ZnII in 2−4. Of these, 2 and 4 are rare examples of a cocrystallized cationic/anionic complex and of a dinuclear complex bridged by a single azide, respectively. Some of these unexpected findings and some interesting noncovalent interactions leading to the formation of dimeric entities in solid-state compound 4 were rationalized by a DFT approach. Photoluminescence properties of the complexes as well as the ligands were investigated in solution at ambient temperature and at 77 K. The very fast photoinduced electron transfer (PET) from the nitrogen lone pair to the conjugated phenolic moiety is responsible for very low quantum yield (Φ) exhibited by the ligands, whereas complexation prevents PET, thus enhancing the Φ in the complexes. The origin of the electronic and photoluminescence properties of the ligands and complexes was assessed in light of theoretical calculations

Combined Experimental and Theoretical Investigation of Ligand and Anion Controlled Complex Formation with Unprecedented Structural Features and Photoluminescence Properties of Zinc(II) Complexes

By using two potential tridentate ligands, HL¹ [4-chloro-2-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol] and HL² [4-chloro-2-[(3-morpholin-4-yl-propylimino)-methyl]-phenol], which differ by one methylene group in the alkyl chain, four new Zn^II complexes, namely, [Zn­(L²H)₂]­(ClO₄)₂ (<b>1</b>), [Zn­(L¹)­(H₂O)₂]­[Zn­(L¹)­(SCN)₂] (<b>2</b>), [Zn­(L¹)­(dca)]_<i>n</i> (<b>3</b>), and [Zn₂(L¹)₂(N₃)₂(H₂O)₂] (<b>4</b>) [where dca = dicyanamide anion] were synthesized and structurally characterized. The results indicate that the slight structural difference between the ligands, HL¹ and HL², because of the one methylene group connecting the nitrogen atoms provokes a chemical behavior completely different from what was expected. Any attempt to isolate the Zn­(L²) complexes with thiocyanato, dicyanamido, and azide was unsuccessful, and perchlorate complex <b>1</b> was always obtained. In contrast, with HL¹ we obtained structural diversity on varying the anions, but we failed to isolate the analogous perchlorate complex of HL¹. Single-crystal X-ray analyses revealed that the morpholine nitrogen of ligand L² is protonated and thus does not take part in coordination with Zn^II in complex <b>1</b>. On the other hand, the morpholine nitrogen of L¹ is coordinated to Zn^II in <b>2</b>–<b>4</b>. Of these, <b>2</b> and <b>4</b> are rare examples of a cocrystallized cationic/anionic complex and of a dinuclear complex bridged by a single azide, respectively. Some of these unexpected findings and some interesting noncovalent interactions leading to the formation of dimeric entities in solid-state compound <b>4</b> were rationalized by a DFT approach. Photoluminescence properties of the complexes as well as the ligands were investigated in solution at ambient temperature and at 77 K. The very fast photoinduced electron transfer (PET) from the nitrogen lone pair to the conjugated phenolic moiety is responsible for very low quantum yield (Φ) exhibited by the ligands, whereas complexation prevents PET, thus enhancing the Φ in the complexes. The origin of the electronic and photoluminescence properties of the ligands and complexes was assessed in light of theoretical calculations