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A detailed study on potential sources, variation, and environmental effects of the rainwater ions was carried out at Lothian Island, Sundarban mangrove forest, India, during the southwest monsoon (June–September) in 2019. On an event basis, the maximum rainwater precipitation was observed 17.65 mm Day −1 and a minimum of 1.02 mm Day −1. The maximum amount of total precipitation was recorded in the month of July (237 mm). The volume weighted mean (VWM) concentration shows that the total ionic composition was 93.7 μeq L−1, whereas the percentage contribution of the total ionic concentration is found to be 45.97% to anions and 54.02% to the cations. Temporal variation was observed between early (June- July) and late monsoon (August—September), which shows a high concentration of major ions in early monsoon and low concentration in late monsoon due to the washout of atmospheric particles with the frequent and increasing precipitation. The pH values of the 78% samples show neutral pH and neutralization factors (NF) followed a sequence of NFCa ˃NFMg ˃ NFNH4 with factors of 0.77, 0.34, and 0.14 indicating Ca2+ was the most potential species to balance the acidic ions (NO3−, SO42−) over the study area. Source apportionment study indicates the significant influence of marine actions (long-range transport by monsoonal wind from marine origin, Sea spray, salty soil profile of mangrove) as the major source of ions over Sundarban. The rate of nutrient wet deposition in the form of rainwater was estimated and average monsoonal nitrogen flux was observed 0.87 kg ha−1where NO3 contributes the most (0.60 kg ha−1). N and P deposition flux also showed a simultaneous pattern with the seasonal nutrient concentration of surrounding river water, which may be an indication of a possible contribution of atmospheric wet deposition in the spike of monsoonal nutrient concentration in river water. [ABSTRACT FROM AUTHOR]

Coastal areas play an important role in the global food and economic system, but are vulnerable to a number of coastal hazards such as cyclones and storm surges. The Sundarban Biosphere Reserve (SBR) is located on the east coast of India and has a rich diversity of aquatic and terrestrial flora and fauna. The region is frequently affected by coastal hazards such as cyclones and storm surges. The objective of this study is to investigate the impact of Super Cyclone Amphan on land use land cover (LULC) in SBR. For this purpose, the land use land cover (LULC) map of the study area before and after the cyclone was first constructed using four machine learning algorithms: Support Vector Machine (SVM), Spectral Angle Mapper and Maximum Likelihood Classifier. In addition, the accuracy of these methods was evaluated using the confusion matrix. The result shows that the SVM basis provides better accuracy than the other methods. After evaluating the accuracy, the detection of changes in the LULC was analysed. The result shows that forest cover in the region decreased significantly (about 38.8%) due to super cyclone Amphan. In addition, agricultural land, swamps, sandbanks and beaches increased by 49.51%, 39.57%, 17.40% and 6.93% respectively. The findings of this study can be used by local and state disaster management authorities to prepare the effective disaster management plans for the region. [ABSTRACT FROM AUTHOR]

Halotolerant plant growth promoting rhizobacteria (PGPR) are beneficial microorganisms utilized to mitigate the biotic and abiotic stresses in plants. The areas of Sundarban mangroves of West Bengal, India have been reported to be rich in halotolerant microflora, yet major area remains unexplored. The present study, therefore, aims to map down the region-specific native microbial community potent of salt tolerance, plant growth promoting (PGP) activity and antagonistic activity against fungal pathogens. Bacterial samples were isolated from the saline soil of the Sundarban mangroves. A total of 156 bacterial samples were isolated and 20 were screened for their salt tolerance potential. These isolates were characterised using morphological, biochemical, and molecular approaches. Based on 16s rRNA sequencing, they were classified into 4 different genera, including Arthrobacter sp. (01 isolate), Pseudomonas plecoglossicida (01 isolate), Kocuria rosea (01 isolate), and Bacillus (17 isolates). The halotolerant isolates which possessed plant growth promoting traits including phosphate, and zinc solubilization, indole acetic acid production, siderophore, and ammonia generation were selected. Further, the effect of two halotolerant isolates GN-5 and JR-12 which showed most prominent PGP activities was evaluated in pea plant under high salinity conditions. The isolates improved survival by promoting germination (36 to 43%) and root-shoot growth and weight of pea plant in comparison to non-inoculated control plants. In a subsequent dual culture confrontation experiment, both these halo-tolerant isolates showed antagonistic activities against the aggressive root rot diseasecausing Macrophomina phaseolina (Tassi) Goid NAIMCC-F-02902. The identified isolates could be used as potential bioagents for saline soils, with potential antagonistic effect on root rot disease. However, further studies at the physiological and molecular level would help to delineate a detail mechanistic understanding of broad-spectrum defence against salinity and potential biotic pathogen. [ABSTRACT FROM AUTHOR]

COVID-19 lockdown enforced distressed reverse migration in Sundarban, which caused an unprecedented population addition to the already devastated fragile Sundarban ecosystem. Acute poverty and food crisis prompted many migrants to explore forest-based living, thus enhancing fatal human–tiger conflicts. Families of deceased migrants face significant mental health trauma and catastrophic psychosocial consequences. [ABSTRACT FROM AUTHOR]

Spanning across Bangladesh and India, the Sundarban Delta consists of over a thousand islands, the majority of which are protected. These islands are important for the rich biodiversity and unique species found here. However, these islands are also at the forefront of climate change due to the impact of rising sea levels and extreme weather events. Therefore, we analyzed the long-term transformations in the land use land cover (LULC) between 1999 and 2020. We used a variety of geostatistical methods, including optimized hot spots cold spots and join count statistics, to examine the spatial patterns of changes in LULC across the study area. The results of our analysis revealed substantial changes in the spatial patterns of mangroves and pond aquaculture. The changes revealed a distinct north-south demarcation in spatial patterns, in the form of clustering of mangroves in the uninhabited islands located in the south and pond aquaculture clustered in the northern inhabited islands. The loss of area under mangroves was concentrated in the southern edges of the islands, which were most exposed to erosion in the open ocean. Nevertheless, we observed an increase in the area under mangroves in some of the northern riverine islands (17 km 2 ). In the case of pond aquaculture, it was mostly concentrated in inhabited islands in the north. Most of the expansions were concentrated in the Indian part of the delta (631 km 2 ). It is noteworthy that because of effective conservation measures, there was very limited overlap between mangroves and pond aquaculture, denoting the conversion of agricultural land to pond aquaculture instead of mangroves. Thus, the results of our study revealed the importance of local level conservation policies and anthropogenic activities, such as deforestation and local level disturbance like over-extraction of water and pollution, on the changing patterns of LULC across this unique, fragile ecosystem. Future studies may incorporate a finer resolution time series of LULC changes over time and space to enable more detailed analysis., (© 2024. The Author(s).)

Floral biochemistry and stress physiology is an underexplored aspect of mangroves, which should be investigated as part of preservation and restoration efforts. A thriving true mangrove tree (Bruguiera gymnorrhiza (L.) Lamk.) and a threatened mangrove-associate species (Heritiera fomes Buch. Ham.) were studied in the Sundarban region of India for seasonal variations in floral odours, non-volatile phytochemicals, antioxidant enzyme activities, and surface water chemistry in surrounding habitat. Both species were found to exhibit significant differences in floral volatilomes, protein contents, antioxidant enzyme activities, total flavonoids, and total phenolic contents between spring and autumn blooms. The bird-pollinated flowers of B. gymnorrhiza also showed considerable seasonal differences in floral anthocyanin and proline contents, indicating vulnerability of the post-anthesis open flowers to environmental factors. Contrarily to previous findings, B. gymnorrhiza floral bouquet appeared to be enriched in various classes of volatiles - dominated by sulphurous compounds in bud stage and terpenoids in open stage. Floral anthocyanins, contributing to the striking colouration of the calyx, were found to comprise cyanidin and delphinidin derivatives. Other glycosides of cyanidin and delphinidin were detected in H. fomes flowers, contributing to visual guides to potential food rewards for pollinating insects. Floral tissue in H. fomes was found to be protected by densely overlapping layers of stellate trichomes containing sesquiterpenoids as phytoprotectants. Comparison of the two floral species suggested that H. fomes flowering is optimized to oligohaline (but not freshwater) vernal conditions; whereas B. gymnorrhiza blooms are adapted for biologically enriched (including abundant herbivores and microbial growth), mesohaline forest habitats., (© 2024. The Author(s) under exclusive licence to The Botanical Society of Japan.)

A cyclone temporarily disrupts copepod community structure of an estuary, and during the community rebuilding process, omnivorous copepods dominate. This hypothesis was tested after cyclone Fani affected the Ganges River estuary of India on 5 May 2019. Copepod assemblages and environmental parameters were collected before (25 February 2019), after (24 August 2019) and immediately after (daily between 8 and 14 May 2019) cyclone Fani from three sites of the estuary. Immediately after cyclone Fani, spatial heterogeneity of the estuarine environment was washed away, salinity and temperature levels of the estuary increased, pH level declined, while the total dissolve solids remained constant at high levels of concentration. Copepod diversity and abundance were drastically reduced by cyclone Fani with the exception of the omnivorous Bestiolina similis, which tolerated a wide variability of the environment and dominated the community. Led by small and medium-sized copepods, within days, the community recovered from its initial disruption. Immediately after cyclone Fani, medium-sized omnivorous copepod Acartiella tortaniformis became the second most abundant species replacing the small-sized herbivorous Paracalanus parvus. Changes in species composition and abundance hierarchy observed immediately after cyclone Fani lasted for a few months. The intensity of cyclones is increasing in the Indian Sundarban; therefore, following a cyclone, more severe and prolong disruptions of the copepod community are likely. Institutionalized monitoring of the cyclone-mediated ecological changes of the Ganges River estuary is therefore strongly recommended. [ABSTRACT FROM AUTHOR]

Mangroves have wide applications in traditional medicines due to their several therapeutic properties. Potentially toxic elements (PTEs), in mangrove habitats, need serious concern because of their toxicity, bioaccumulation capacity and ecotoxicological risks. In the current study, we aimed to examine sediment quality and bioaccumulation of PTEs in a mangrove-dominated habitat of Sundarban, India, and their relation with antimicrobial property of ten mangrove species of the region. Antimicrobial activity of different solvent fractions of mangrove leaves was assessed against seven microorganisms. The highest antimicrobial activity was detected in ethyl acetate and acetone-extracted fractions of Avicennia alba. Various sediment quality indices revealed progressively deteriorating nature of surface sediment having moderate contamination, however, low ecotoxicological risk. The accumulation factors (AF) for different PTEs indicate a gradual metal bioaccumulation in leaf tissue. Antimicrobial activities indicated both positive and negative correlations with manganese (Mn), copper (Cu), iron (Fe) and zinc (Zn) concentrations of mangrove species. Concentration of Mn showed a significant correlation with almost all the fractions, whereas Cu had correlation with ethyl acetate, acetone and methanol fractions (P < 0.05). The AF of Mn and Cu exhibited correlation with antimicrobial activities of acetone and methanol fractions, whereas Fe and Zn had correlation with hexane and ethyl acetate fractions. Overall, Mn, Fe, Cu and Zn concentrations of Acanthus ilicifolius and Avicennia alba leaves and in the surface sediments demonstrated the strongest association (P < 0.05) with their antimicrobial activity as also depicted in correlation and cluster analysis studies. Thus, this study will help to establish a link between the PTEs in mangrove ecosystem with their bioactivity. [ABSTRACT FROM AUTHOR]

Aims: Human-tiger conflict (HTC) is a serious public health issue in Sundarban Reserve Forest, India. HTC is a continued concern for significant mortality and morbidity of both human and tiger population. This study examined 49 widows, whose husbands were killed by tigers, in order to explore the cultural stigma related with tiger-killing and consequent discrimination and social rejection. Different psychosocial aspects of community stigma associated with tiger-killings is discussed in the context of local culture. Methods: A mix of both quantitative and qualitative methods was used in this ethnographic study in two mouzas of Sundarban adjacent to Reserve Forest, involving (1) Village Survey for Tiger-widows, (2) In-depth interview of the widows, (3) Focus Group discussions, (4) Participatory mapping and (5) Stigma assessment by using a 28 item stigma scale especially devised for this research. For comparison of stigma-burden snake-bite widows and normal widows were taken from the same community. Results: Tiger-widows showed significantly higher stigma scores on all the clusters (fear, negative feelings, disclosure, discrimination, community attitudes, and spiritual dimension) than from both normal and snake-bite widows. They also showed higher total stigma score (65.9 ± 9.8) than normal widows (35.8 ± 8.0) and snake-bite widows (40.1 ± 7.1) and this difference was highly significant (P < 0.001). IDIs and FGDs helped to unfold the cultural construct of stigma related to tiger-killing. This can be seen in how the tiger-widows' quality of life has been negatively impacted with a multitude of post-trauma psychological scars, deprivation, abuse and exploitation. Conclusions: The study proposes that administrative strategy for sustainable alternative income generation and conservation policy with integrated participatory forest management may save both human and tiger. A community ecocultural mental health programme addressing to eradicate the cultural stigma related with tiger attack, with environmental awareness may help to reduce the social miseries of the tiger-widows. [ABSTRACT FROM AUTHOR]

Like many coastal systems, nitrogen is the critical limiting factor for mangrove net production. This study used a box model approach to assess the nitrogen budget in the Sundarban mangrove ecosystem, which acts as a sink for atmospheric nitrogen in terms of NO x , NH 3 , N 2 , and water column dissolved inorganic nitrogen. The coupling of biosphere and atmosphere in terms of atmospheric NO x and NH 3 uptake showed that uptake of ammonia (130 × 10 6 mol yr − 1 ) was about six fold as large as that of NO x, (22 × 10 6 mol yr − 1 ). The nitrogen stored by the processes such as plant uptake of NO x , NH 3 from the atmosphere, nitrogen fixation (5 × 10 9 mol yr − 1 ), and sediment water exchange (8 × 10 6 mol yr − 1 ) was about two times as large as that of recycled nitrogen from litter (3 × 10 9 mol yr − 1 ), and could account 74% of the nitrogen required for mangrove net production. Most of the nitrogen was conserved in the living biomass (living biomass: 118 × 10 3 mol ha − 1 versus soil: 3 × 10 3 mol ha − 1 ). The loss of nitrogen was 23% of the total amount that was conserved from the external sources in the Sundarban mangrove system. Thus, the coastal ecosystem like Sundarban mangroves could retain only 0.2% (8 × 10 6 mol) of the annual river flux of nitrogen to the coastal waters and nitrogen is generally conserved within the system. [ABSTRACT FROM AUTHOR]

Blackspotted Croaker (Protonibea diacanthus) is one of the most commercially important croakers which migrate along West Bengal coast during winter season. This paper deals with the importance of the species along with its market value and the cause of its popularity in West Bengal. This species is gaining prime importance among the fishermen due to the high market price of its swim bladder. The dried swim bladders are sold in local markets for Rs. 40,000-50,000 per kg. There is a risk factor involved as the fishermen do not get the catch at a time and, moreover, they often lose common pelagic fishes due to the usage of larger mesh nets. In spite of this risk, a shift from pelagic to demersal fishing across the northern Bay of Bengal marks an important emerging trend of winter fishing in this area. [ABSTRACT FROM AUTHOR]

Famous for the abode of man-eating Royal Bengal tiger Sundarban is a UNESCO world heritage site, biosphere reserve, largest delta and largest mangrove eco-system in the world. Agriculture and animal husbandry is the primary livelihood of people living in this region. Marketing is an important aspect of livestock production which has complementary and supplementary relationship with agriculture. Therefore, live-stock and livestock products marketing in rural Sundarban is a virgin field of research. Since, interview and questionnaire-based research largely fail to capture the diversity and complexity of rural social reality case study method of PRA (Participatory Rural Appraisal) was used to understand livestock marketing system in four selected villages of Sundarban delta in India. Villages were selected based on backwardness, remoteness, and livelihood. Listing, topical interview, oral trend and ranking methods of PRA were employed to collect data. Data was verified through personal observation and key-informant discussion. Study reveals that a localized informal marketing system existed in the study area with a linkage to larger market of outside via the middleman (vendor). Further, it seems that marketing of livestock and its products was secondary to livestock production. Rules and regulations of marketing as well as the price of livestock and its products were standardized and determined informally based on local criteria and external market forces. Thus, the study provides useful insights into the marketing system of livestock and underlying social realities governing its functioning in Sundarban islands. It is concluded that similar kind of research conducted on a large scale will help development professionals and policy makers to plan and implement development programs in Sundarban where backwardness and rich natural resources paradoxically co-exist. [ABSTRACT FROM AUTHOR]

A comprehensive attempt has been made to evaluate the diurnal and spatial pattern of CO exchange between the atmosphere and water along the estuarine track of Indian Sundarbans during the two summer months, April and May, 2011. Rigorous field observations were carried out which included the hourly measurements of total alkalinity, pH, fugacity of CO in ambient air and water surface, dissolved oxygen, and chlorophyll a. The estuarine water was found rich in total alkalinity and was oversaturated with CO throughout the diurnal cycle in the two stations situated at the inner and middle estuary, respectively, whereas an entirely reverse situation was observed in the outer fringes. The fugacity of CO in water ranged from 152 to 657 μatm during the study period. The percentage of over-saturation in inner and middle estuary varied from 103 to 168 and 103 to 176 %, respectively, whereas the degree of under-saturation in the outer estuary lied between 40 and 99 %. Chlorophyll a concentrations were found higher in the outer estuary (12.3 ± 2.2 mg m) compared to the middle (6.4 ± 0.6 mg m) and inner parts (1.6 ± 0.2 mg m), followed by a similar decreasing pattern in nutrient availability from the outer to inner estuary. The sampling stations situated at the inner and middle estuary acted as a net source of 29.69 and 23.62 mg CO m day, respectively, whereas the outer station behaved as a net sink of −33.37 mg CO m day. The study of primary production and community respiration further supports the heterotrophic nature of the estuary in the inner region while the outer periphery was marked by dominant autotrophic character. These contrasting results are in parity with the source characters of many inner estuaries and sinking characters of the outer estuaries situated at the distal continental shelf areas. [ABSTRACT FROM AUTHOR]

The above canopy carbon dioxide and water vapour fluxes were measured by micrometeorological gradient technique at three distant stations, within the world's largest mangrove ecosystem of Sundarban (Indian part), between April 2011 and March 2012. Quadrat analysis revealed that all the three study sites are characterized by a strong heterogeneity in the mangrove vegetation cover. At day time the forest was a sink for CO, but its magnitude varied significantly from −0.39 to −1.33 mg m s. The station named Jharkhali showed maximum annual fluxes followed by Henry Island and Bonnie Camp. Day time fluxes were higher during March and October, while in August and January the magnitudes were comparatively lower. The seasonal variation followed the same trend in all the sites. The spatial variation of CO flux above the canopy was mainly explained by the canopy density and photosynthetic efficiency of the mangrove species. The CO sink strength of the mangrove cover in different stations varied in the same way with the CO uptake potential of the species diversity in the respective sites. The relationship between the magnitude of day time CO uptake by the canopy and photosynthetic photon flux was defined by a non-linear exponential curve (R ranging from 0.51 to 0.60). Water vapour fluxes varied between 1.4 and 69.5 mg m s. There were significant differences in magnitude between day and night time water vapour fluxes, but no spatial variation was observed. [ABSTRACT FROM AUTHOR]

This paper documents the concentration of total arsenic and individual arsenic species in four soft-bottom benthic polychaetes ( Perenereis cultifera, Ganganereis sootai, Lumbrinereis notocirrata and Dendronereis arborifera) along with host sediments from Sundarban mangrove wetland, India. An additional six sites were considered exclusively for surface sediments for this purpose. Polychaetes were collected along with the host sediments and measured for their total arsenic content using inductively coupled plasma mass spectrometry. Arsenic concentrations in polychaete body tissues varied greatly, suggesting species-specific characteristics and inherent peculiarities in arsenic metabolism. Arsenic was generally present in polychaetes as arsenate (As ranges from 0.16 to 0.50 mg kg) or arsenite (As ranges from 0.10 to 0.41 mg kg) (30-53 % as inorganic As) and dimethylarsinic acid (DMA <1-25 %). Arsenobetaine (AB < 16 %), and PO-arsenoriboside (8-48 %) were also detected as minor constituents, whilst monomethylarsonic acid (MA) was not detected in any of the polychaetes. The highest total As (14.7 mg kg dry wt) was observed in the polychaete D. arborifera collected from the vicinity of a sewage outfall in which the majority of As was present as an uncharacterised compound (10.3 mg kg dry wt) eluted prior to AB. Host sediments ranged from 2.5 to 10.4 mg kg of total As. This work supports the importance of speciation analysis of As, because of the ubiquitous occurrence of this metalloid in the environment, and its variable toxicity depending on chemical form. It is also the first work to report the composition of As species in polychaetes from the Indian Sundarban wetlands. [ABSTRACT FROM AUTHOR]

The present work is the first attempt to compare the data of a comprehensive study of the origin and distribution of 16 priority pollutant polycyclic aromatic hydrocarbons (PAHs) in surface sediments (<63 μm) from 18 sampling stations, 9 from Sundarban of Bangladesh and 9 from Indian counterpart. Σ19PAHs concentration in sediments showed wide variations from 208.3 to 12,993.1 ng g dry weight in Indian Sundarban, whereas 208.4 to 4,687.9 ng g in the case of Bangladesh. Fluoranthene, pyrene, benzo(b)fluoranthene, benzo(a)pyrene and dibenzo(a,h)anthracene were predominant species for both the countries. The PAH diagnostic ratios indicated that the PAHs in sediments from both the countries were of mixed source of hydrocarbons of both petrogenic and pyrolytic origin. According to the numerical effect-based sediment quality guidelines, the levels of PAHs in the Sundarban wetland of Bangladesh and India should not exert adverse biological effects. The TEQ values calculated for samples from the Bangladesh and Indian Sundarban varied from 13.68 to 1,014.75 and 1.31 to 2,451 ng g d.w. with an average of 221.02 and 358.63 ng g, respectively. The overall contamination status of PAH was higher in India than Bangladesh. [ABSTRACT FROM AUTHOR]

A sequential extraction procedure was carried out to determinate the concentrations of 11 elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in different geochemical phases of sediments collected along the Hugli (Ganges) River Estuary and in the Sundarban mangrove wetland, eastern coastal part of India. The chemical speciation of elements was determined using the three-step sequential extraction procedure described by the European Community Bureau of Reference. Total metal concentration was determined using a microwave-assisted acid digestion procedure. Metal concentrations were near the background level except for As for which a moderate pollution can be hypothesized. The mobility order of the metals was: Cd > Mn > Cu > Zn > As > Co > Pb > Ni > Fe > Cr > Al. The highest percentage of Cd (>60%) was found in the most labile phase. Residual fraction was prevailing for Fe, Cr and Al, while Pb was mainly associated with the reducible fraction. Data were compared with Sediment Quality Guidelines to estimate the relationship between element concentrations and adverse biological effects on benthic community, finding the possibility of some toxic effects due to the presence of As in the entire studied area and Cd, only in Calcutta. [ABSTRACT FROM AUTHOR]

The Sundarban is the largest mangrove ecosystem, which is presently vulnerable to climate change related impacts. The western part of it falls in the state of West Bengal between the estuaries of the Hooghly and Ichamati-Raymongal Rivers. The diversity of the genus Ceratium Schrank and the related physicochemical parameters such as Sea Surface Temperature (SST) was studied in the Hooghly-Matla estuary and offshore. Five species of bio-indicator dinoflagellate, Ceratium were identified in the bloom-forming season. The species are: C. furca, C. fusus, C. symmetricum, C. trichoceros and C. tripos. C. symmetricum was not previously reported from the Indian part of the Sundarban and is now found in low abundance. The other four species are less sensitive to warming or rise in SST. A comparative study of the day time SST from the satellite images of the year 2003 to 2009 of the months of January and February reveals a rising winter SST. Compared to the previous years, the increase in temperature can be one of the causative factors to explain the lower abundance of C. symmetricum compared to the others. With further rise of the SST, there is a possibility that this species may no longer be found in abundance in the western part of adjoining Hooghly-Matla estuarine system. [ABSTRACT FROM AUTHOR]

Elevated concentrations of arsenic in the sediment and pore water in the Sundarban wetlands pose an environmental risk. Adsorption and desorption are hypothesized to be the major processes controlling arsenic retention in surface sediment under oxic/suboxic condition. This study aims to investigate sorption kinetics of As(III & V) and its feedback to arsenic mobilization in the mangrove sediment. It ranges from sand to silty clay loam and shows the adsorption of As(III & V) following the Langmuir relation. Estimates of the maximum adsorption capacity are 59.11 ± 13.26 μg g for As(III) and 58.45 ± 8.75 μg g at 30°C for As(V) in the pH range 4 to 8 and salinity 15-30 psu. Extent of adsorption decreases with increasing pH from 4 to 8 and desorption is the rate-limiting step in the reaction of arsenic with sediment. Arsenic in the sediment could be from a Himalayan supply and co-deposited organic matter drives its release from the sediment. Arsenic concentration in the sediment is well below its maximum absorption capacity, suggesting the release of sorbed arsenic in pore water by the microbial oxidation of organic matter in the sediment with less feedback of adsorption. [ABSTRACT FROM AUTHOR]

The study reports the first assessment for the quantification and speciation of butyltins (BTs) in surface marine sediment samples (0-5 cm) from intertidal mudflats of Sundarban mangrove wetland along with the Hugli (Ganges) river basin, eastern coastal part of India. Concentrations of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) were monitored at 16 stations and present at all study areas, in concentrations in sediments up to 84.2, 26.4 and 48.0 ng g of TBT, DBT and MBT, respectively. Significant correlations were obtained between MBT and DBT ( r = 0.62, p = 0.01) and DBT and TBT ( r = 0.54, p = 0.03). Calculated BT degradation index (BDI) values indicated recent contamination of BTs at 8 stations, and suggested either no degradation of TBT or very recent degradation at a 4 further stations. Additionally, BDI values also indicated no recent inputs of BTs in 4 stations (only MBT present in one of these stations). High concentrations of BTs, particularly TBT, have the potential to induce ecotoxicological impacts based on levels specified in Australian Sediment Quality Guidelines (SQGs). This study indicated that the majority of the analyzed stations were in the highest range of priority, due to high TBT concentrations. [ABSTRACT FROM AUTHOR]

Famous for the abode of notorious man-eating Royal Bengal Tiger Sundarban is largest delta and largest mangrove forest belt on earth. It is a UNESCO World Heritage Site. A participatory rural appraisal (PRA) was conducted (2003-04) in four purposively selected villages in Sundarban islands (Gangetic delta) of India to understand the social trend over a long period of time. PRA tools (oral history and time line) were applied to obtain information on various aspects of rural social life tracing back to the past. PRA reveals that rural people in Sundarban lived a tough life in recent past. Though a remarkable change in various aspects of village life has occurred in due course of time a lot has to be done to develop rural Sundarban compared with other developed regions of India. It was also observed that a little change has been brought by the programs planned and implemented by the government. It is recommended that before undertaking any program of promoted change perspectives of the villagers must be taken into consideration with an emphasis on environmental issues. [ABSTRACT FROM AUTHOR]

This study attempts to establish the challenges associated to solar energy scenario in rural living of south-east of Indian province namely West Bengal and to suggest an inexpensive solar artifact with an aim to cater to the areas which are scarcely electrified and primarily in countryside. Stockpile of fossil fuels are depleting and there is an urgent need of promoting renewable energy products that can pertinently be supported by this clean energy. Renewable energy is alternate source of energy or nonconventional energy such as, solar energy, water energy, wind energy, biomass and bio-gas energy, tidal energy, Geo-thermal energy, hydrogen energy. Scope of this article converges on disregarded demand scenario of rural inhabitants and fostering inexpensive appropriate solar technology based product. For subsequent investigation a critical socio-technical survey has also been conducted in the rural Sundarban area of Southern part of West Bengal, with an aim to acquire the glimpse of the presently operating government project on solar technology and to identify the demand and solar product there for. [ABSTRACT FROM AUTHOR]

Abstract: The study evaluated the economic, ecological and socio-cultural achievements of improved earthen stoves that were provided to the beneficiaries under a project to improve decreasing biomass energy utilization. A questionnaire was developed and a random sampling method was employed for selecting the samples from the population. The region has undergone a significant change with the development of shrimp aquaculture in brackish water on former paddy field. As a result the households have become dependent on the wood resources of the Sundarban (77% as their first choice of daily fuel). The fuel collection rate from the Sundarban has increased by 30% since the change to aquaculture, while the use of agricultural residues has declined by a similar amount. The introduction of the improved stove with two cook stations and a chimney resulted in a reduction of fuel use (as wood) to 540g caput−1 d−1, from the previous usage of 810g caput−1 d−1 using the traditional stove. Households saved 1.5 kg d−1 of fuel (one third), and reduced the cooking time by 45 min d−1 (about 20%). While 85% of men and 65% of women were the major fuel collectors, the improved stove resulted in a small increase (14 taka) in the women’s contribution to family income as well as a monthly saving on fuel cost of 45 taka. Respondents utilized saved time and money for household means and other economic activities. [Copyright &y& Elsevier]

Objective: Evaluation of various clinico-demographic variables and pattern of domestic violence in non-fatal deliberate self-harm (DSH) attempters admitted in 3 Block Primary Health Centers (BPHC) of Sundarban region of West Bengal, India in the year 2002. Materials and Methods: A prospective study of 89 DSH cases admitted at 3 Sundarban BPHCs by using a specially designed DSH register and a questionnaire on domestic violence in Bengali along with detail clinical interview. Results: Among the total of 89 DSH cases (23 male and 66 female), young (less than 30 years), female sex, low education and married status constituted major part of the sample. Pesticide poisoning was the commonest mode of DSH attempt. Typical stressors found were marital conflict or conflict with in-laws or guardian. A majority of DSH attempters (69.6%) experienced more than one form of domestic violence. Poverty and unemployment in the family were strongly associated with domestic violence. Among female DSH attempters, the most common perpetrator was husband (48.48%) followed by in-laws (16.67%) and parent (34.78%) was the most common perpetrator among males. Conclusion: Both DSH and domestic violence are serious socio-clinical issue of a major public health concern in the Sundarban region. Stressful life situations and various types of victimizations in the family intermixed with easy availability of lethal pesticides in this agriculture dependent community may facilitate the impulse of self-harm behavior, especially among the young housewives. Timely psychosocial intervention through community psychiatry program may mitigate the impact of psycho-cultural stressors and thus may help to reduce the morbidity and mortality from DSH. [ABSTRACT FROM AUTHOR]

Objective To examine the clinical epidemiology, including case fatality and determinants of self-harm in six island blocks of the Sundarban region of West Bengal, India. Methods We examined the clinical records of 1277 patients admitted for deliberate self-harm (DSH) to the six island hospitals from 1999 to 2001. Results 77.7% of the patients survived their attempt, 11.9% died and for 10.4% the outcome was not recorded. Women accounted for 65.2% of the DSH admissions and 67.1% of the deaths. Pesticides were the most commonly used means (88.7%). The case fatality of self-harm reported in these hospitals ranged from 6.0% to 50.0% (mean 13.3%; CI, 11.3–15.3). The age group 55–64 years was at highest risk of death, the age group 15–24 years at lowest risk. Higher lethality of pesticide ingestion compared to other methods was suggestive but not significant. Case fatality within the region varied but was high compared to industrialized nations. Case records and management of DSH were poor. Conclusion Effective DSH prevention in the Sundarban region would require better surveillance at clinical facilities and an intersectoral approach, linking the agricultural interests of pesticide safety and mental health interests for preventing DSH. [ABSTRACT FROM AUTHOR]

Background: Non-fatal deliberate self-harm (DSH), particularly with pesticides, is a major public health problem in many developing countries of the world. Agriculture is the primary occupation of most people living in the Sundarban region in West Bengal, India. Pesticides are extensively used in agriculture, and these agents are most frequently used in DSH. Aim: This study aimed to identify the nature of methods and agents used in non-fatal DSH attempts in the Sundarban area under South 24 Parganas district of West Bengal. Materials and Methods: Detailed demographic and clinical data on DSH cases of 13 Block Primary Health Centres' (BPHCs') admission registers were analyzed. One Focus Group Discussion (FGD) with the Panchayat Samiti of each block (totally 13 FDGs) was conducted to elicit the Samiti members' perception about the problem of pesticide-related DSH or suicide in the region. Results: A total of 5,178 (1,887 male and 3,291 female) subjects were admitted at the BPHCs during the study period from 1999 to 2001. Organophosphorous pesticide poisoning was found to be the most common method (85.1%) in DSH. This emphasizes the importance of developing an urgent poisoning-prevention program with a special focus on improving clinical services, as well as initiating farmers. education programs focusing on safe pesticide practices at the primary-care level. [ABSTRACT FROM AUTHOR]

Background: Deliberate self-poisoning by ingesting pesticides is a serious health problem among farmers, especially in low- and middle-income countries. Preventing these suicides is a priority for a public mental health agenda.Objective: To examine the role of pesticide poisoning in suicide and nonfatal deliberate self-harm, and clarify awareness of risks, safe practices concerning storage and use of pesticides, and associated self-injury, both unintentional and intentional, within farmer households of the Sundarban region, India.Methods: Retrospective record review of adult cases of deliberate self-poisoning at the Block Primary Health Centres of 13 Sundarban Blocks was performed to analyze the relative roles of various methods of self-harm and their lethality. Focus group discussions, questionnaires, and in-depth interviews were undertaken in a community study of farmer households to examine pesticide-related views and practices, with particular attention to storage, use, and health impact.Results: Pesticide poisoning was the most common method of deliberate self-harm in both men and women. Pesticide storage in most households was unsafe and knowledge was inadequate concerning adverse effects of pesticides on health, crops, and the environment.Conclusions: An intersectoral approach linking the interests of public health, mental health, and agriculture is well suited to serve the collective interests of all three agendas better than each in isolation. Such an approach is needed to reduce morbidity and mortality from unintentional and intentional self-injury in low-income agricultural communities like those of the Sundarban region. [ABSTRACT FROM AUTHOR]

The paper presents the first document regarding concentration, distribution and possible sources of selected trace elements (Cu, Fe, Mn, Zn, Cr, Co, Ni, Pb, Al, B and Ba) in core sediments (<63 μ particle size) from the lower stretch of Hugli (Ganges) estuary, northeast coast of Bay of Bengal by ICP–AES and EDXRF to evaluate geochemical processes influencing their distribution and possible environmental consequences. The levels of elements showed a wide range of variations in different core depths, in upper and lower intertidal zones as well as among three sampling stations. The most interesting feature of the study is the downward increase of concentrations of majority of the elements reaching overall maximum values at a depth of 20–28 cm in upper littoral zone of the site located in the extreme downstream stretch of the estuary. Values of organic carbon showed very strong positive correlations with most of the elements as revealed by correlation matrix (r) values. The interelemental relationship revealed the identical behavior of element during its transport in the estuarine environment. The overall variation in concentration can be attributed to differential discharge of untreated effluents originating from industrial, agricultural, and aquacultural sources as well as from domestic sewage along with the fishing and boating activities. The resulting compositional dataset was tested by principal component analyses and cluster analyses. Pollution load index (PLI) and index of Geoaccumulation (I geo) revealed overall low values but the enrichment factors (EFs) for Pb were typically high for all the stations. The mean concentrations of Zn and to some extent Cu exceeded the Effects Range-Low (ER-L) values in the majority of the cases indicating that there may be some ecotoxicological risk to organisms living in sediments. The concentration of the trace elements reported in this work is useful as baselines for comparison in future sediment quality studies. [Copyright &y& Elsevier]

Abstract: The Sundarban mangrove forest (4264km2) is about 3% of the total area of the world mangrove is interdependent on the coastal aquatic subecosystem (1781km2). Ammonia concentration and flux measurements in the mangrove ecosystem and measurements in such tropical land–ocean boundary conditions are few and far between. A micrometeorological method was used to measure ammonia exchange over Sundarban mangrove forest and aquatic subecosystem. Results showed both emission and gaseous dry deposition in the forest area at a rate 1.79×103 and 2.26×103 kgNkm–2 yr−1, respectively. Flux of ammonia in the aquatic subecosystem was found always from air to water with a rate of 775.7kgNkm–2 yr−1. The annual particulate dry and wet atmospherically deposited ammonia flux were calculated to be 69.0 and 21.5kgNkm–2 yr−1, respectively. Exchange of gaseous ammonia in the mangrove forest showed net deposition with a rate of 4.90×102 kgNkm–2 yr−1. Annual imported flux from the proximate terrestrial source to this virgin forest was found to be 4.26×106 kgNyr−1 out of which 32.9% was deposited to the coastal water. Ammonia compensation point for mangrove vegetation was found to occur between 51 and 421nmolm−3 and its variation was related to wind velocity, temperature, and humidity. [Copyright &y& Elsevier]

The Ganga is the most important perennial river originating from Gangotri in the snow-bound Himalayas about 3,900 m above mean sea level. Gorging a distance of about 220 km in the Himalayas, it enters the plain at Hardwar and after meandering and braiding over a distance of about 2,525 km through the Indo-Gangetic plains, ultimately joins the Bay of Bengal. The course of this river has been changed due to: (i) subsurface geotectonic movement leading to change in slope of the deltaic plain and subsidence of the Bengal basin; (ii) changing pattern of water discharge with time; (iii) variations in sediment load. The environment of Ganga basin is also deteriorating with time due to severe natural episodes of periodic floods and storms as well as anthropogenic factors such as population growth, deforestation, agricultural activities, urbanisation, fertiliser and fossil fuel consumption and construction activities such as dams and bridges. All these have inconceivable adverse impacts on the health and natural regeneration capacity of the river basin. The presence of micropollutants in water and sediments of this river turns the system into being unsustainable to the biota. The present study synthesises the available information on the changes of its geological, geomorphological and ecological aspects and suggests some remedial measures to be adopted now and in future. [ABSTRACT FROM AUTHOR]

Diurnal and seasonal variations in carbon dioxide and methane fluxes between Sundarban biosphere and atmosphere were measured using micrometeorological method during 1998–2000. Study of the diurnal variation of micrometeorological conditions in the atmosphere was found to be necessary to determine the duration of neutral stability when flux estimation was reliable. Neutral stability of the atmosphere occurred in the limited micrometeorological conditions, when friction velocity ranged between 0.360 and 0.383 m s−1. The value of drag coefficient (1.62–20.6)×103 obtained at variable wind speed could be deemed specific for this particular surface. 58.2% drop of carbon dioxide and 63.4% drop of methane in the atmosphere at 1 m height were observed during day time, between dawn and early evening. Diurnal variations in methane and carbon dioxide mixing ratios showed a positive correlation with Richardson''s number (Ri). This environment acted as a net source for carbon dioxide and methane. The mixing ratios of methane were found to vary between 1.42 and 2.07 ppmv, and that of carbon dioxide, between 324.3 and 528.7 ppmv during the study period. The biosphere–atmosphere flux of carbon dioxide ranged between −3.29 and 34.4 mg m−2 s−1, and that of methane, between −4.53 and 8.88 μg m−2 s−1. The overall annual estimate of carbon dioxide and methane fluxes from this ecosystem to atmosphere were estimated to be 694 Tg yr−1 and 184 Gg yr−1, respectively. Considerable variations in mixing ratios of carbon dioxide and methane at the NE coast of Bay of Bengal were observed due to the seasonal variations of their fluxes from the biosphere to the atmosphere. The composition was inferred by fitting model prediction to measurements. [Copyright &y& Elsevier]

Global climate change induced warming has profound repercussion on physiological performances of marine animals. The Indian Sundarban is one of the best nursery grounds for various shrimp populations which need estuarine realm to complete their bipartite life cycle. From last couple of decades, a clear indication of temperature escalation has been identified in Sundarban. In the present study, we have assessed the physiological energetics of Penaeus monodon post larvae from Indian Sundarban under different temperatures, 28 °C (annual average habitat temperature) and elevated temperatures 30 °C, 32 °C, 34 °C in a month long mesocosm experiment. Significant alterations were observed in growth performances as well as physiological energetics. The length, weight, survival percentages, ingestion rates were reduced, howbeit respiration and ammonia excretion rate had been increased in elevated temperature treatments culminating in a negative Scope for Growth. PERMANOVA results showed a significant (p ≤ 0.05) variation in different physiological performances of shrimp post larvae both in different temperature treatments and days of exposure. The present results clearly highlighted the detrimental effect of elevated temperature on physiological energetics of shrimp larvae that might potentially reduce shrimp population and affect the coastal fishery., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The transboundary River Ganga serves as a conduit for meltwater from the Himalayas and is a major freshwater source for two thirds of Indian population before emptying into the Sundarban Delta, the largest estuary in the Bay of Bengal. Endocrine disrupting compounds (EDCs) such as phthalic acid esters (PAEs) and bisphenol A (BPA) used as organic plastic additives can pollute the aquatic environment receiving plastic litter. Hence, we have investigated these EDCs in water samples from Ganga and Sundarban wetland of India. Since these compounds exhibit estrogenic potential, we have further measured steroids and evaluated the estrogenic activity (estradiol equivalents, BioE2Eqs) using an in-vitro bioassay (E-Screen). Further BioE2Eqs were compared with the sum of predicted estradiol equivalents based on the chemical concentrations of PAEs and BPA by E-Screen (ChemE2Eq) and YES factors (ChemYES). Caffeine was measured as a marker for anthropogenic wastewater discharge. Results showed that the highest BioE2Eq (below the lowest observable effect of E2 on fish) was associated with sites having sewer outfalls in the middle stretch of the river, and concomitantly coinciding with the elevated concentrations of caffeine. Neither ChemE2Eq nor ChemYES correlated with measured BioE2Eqs. River concentrations of BPA (0.04-4.46 µg/L) and ∑ 7 plasticizers (0.43-7.63 µg/L) were higher than BPA (0.21-2.82 µg/L) and ∑ 7 plasticizers (0.85-2 µg/L) in the Sundarban wetland. The only steroids detected were androgens, found at four sites in Ganga (0.007 µg/L± 0.003, mean ± S.D.). The highest estimated ecotoxicological risk to aquatic insect and fish stemmed from BPA. A secondary effect, and a potential impact on human health could be reflected via fish consumption from the productive fisheries region along the lower stretch of River Ganga. Identification of areas of elevated estrogenicity, plasticizer and steroid concentrations in River Ganga can be used to design and implement interventions for the remediation of such emerging contaminants., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The mangrove ecosystems are known to efficiently sequester trace metals both in sediments and plant biomass. However, less is known about the chemistry of rare earth elements (REE) in the coastal environments, especially in the world's largest mangrove province, the Sundarban. Here, the concentration of REE in the sediment and plant organs of eight dominant mangrove species (mainly Avicennia sp.) in the Indian Sundarban was measured to assess REE sources, distribution, and bioaccumulation state. Results revealed that light REE (LREE) were more concentrated than the heavy REE (HREE) (128-144 mg kg -1 and 12-15 mg kg -1 , respectively) in the mangrove sediments, with a relatively weak positive europium anomaly (Eu/Eu* = 1.03-1.14) with respect to North American shale composite. The primary source of REE was most likely linked to aluminosilicate weathering of crustal materials, and the resultant increase in LREE in the detritus. Vertical distribution of REE in one of the long cores from Lothian Island was altered by mangrove root activity and dependent on various physicochemical properties in the sediment (e.g., Eh, pH, organic carbon, and phosphate). REE uptake by plants was higher in the below-ground parts than in the above-ground plant tissues (root = 3.3 mg kg -1 , leaf + wood = 1.7 mg kg -1 ); however, their total concentration was much lower than in the sediment (149.5 mg kg -1 ). Species-specific variability in bioaccumulation factor and translocation factor was observed indicating different REE partitioning and varying degree of mangrove uptake efficiency. Total REE stock in plant (above + live below ground) was estimated to be 168 g ha -1 with LREE contributing ~ 90% of the stock. This study highlighted the efficiency of using REE as a biological proxy in determining the degree of bioaccumulation within the mangrove environment.

Sundarban along with its networks of rivers, creeks and magnificent mangroves form a unique ecosystem. Acid sulphate soils have developed in this ecosystem under anoxic reducing conditions. In the present study, we have investigated the distribution of acid sulphate soils along with its elemental characterization and possible sources in four reclaimed islands of Indian Sundarban like Maushuni (I1), Canning (I2), Bally (I3) and Kumirmari (I4). Elements show moderate to strong correlation with each other (P < 0.01; P < 0.05). Except Si, Ca and Pb, a higher enrichment factor was observed for K, Cr, Mn, Fe, Ni, Cu and Zn. Geo-accumulation index values of all sampling locations reveal that Cr, Fe, Cu and Zn are in I geo class 1. The pollution load index value of the reclaimed islands of Indian Sundarban varies between 1.31 and 1.48. The observation of this study could help to strategize policies to mitigate and manage acid sulphate soils in Indian Sundarban., (Copyright © 2018 Elsevier Ltd. All rights reserved.)