This study aims to investigate the control of arsenic distribution by biogeochemical processes in the Indian Sundarban mangrove ecosystem and the importance of this ecosystem as an arsenic source for surrounding coastal water. The As(V)/As(III) ratio was found to be significantly lower in both surface and pore waters compared to sea water, which could be attributed to biogeochemical interconversion of these arsenic forms. The biological uptake of arsenic due to primary and benthic production occurs during the post-monsoon season, and is followed by the release of arsenic during the biochemical degradation and dissolution of plankton in the pre-monsoon season. These results suggest that arsenic is immobilized during incorporation into the arsenic-bearing initial phase, and unlikely to be released into pore water until the complete microbial degradation of arsenic-bearing organic compounds. © 2009 Elsevier Ltd. All rights reserved.

S K MANDAL

M DEY

D GANGULY

S SEN

T K JANA

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Marine Pollution Bulletin

Distribution of arsenic in the marine environment is associated with its biogeochemical behavior. Indeed, very few studies have been conducted along the seasonal cycle to show its non-conservative behavior in the tropical estuary. The Mahanadi River, one of the major tropical rivers in the peninsular India, drains densely populated and industrialized region of Paradeep port. Over this 1-year study, the variations of inorganic arsenic were examined along the salinity gradient of the Mahanadi estuary, with the aim to provide some insights into the mechanisms that control arsenic concentrations and behavior under estuarine mixing. Arsenic in the estuary was derived from both natural and anthropogenic sources, and it displayed partial removal from the water in the mixing zone. Results of geo-accumulation index indicated that sediments were uncontaminated and they acted as a sink for arsenic. The diffusive fluxes from water to sediment were estimated to be 9.05 μg m−2 day−1 at Chaumohona, 9.83 μg m−2 day−1 at Kaudia, and 11.85 μg m−2 day−1 at Neherubunglow. The findings of the study suggest that both the removal of arsenic by biogeochemical processes and its diffusive transport from water to sediment are of major importance for both the non-conservative behavior of arsenic in the estuary and its export to the coastal water. © 2016, Springer International Publishing Switzerland.

Environmental Monitoring and Assessment

Arsenic distribution in waters and its geochemical behavior in sediment of Mahanadi estuary in India

This study describes the in vitro study of (1:1) one step nucleophilic displacement (S N 1) of phosphate by heavier anion arsenate and arsenite in the DNA of arsenic ridden Sundarban mangroves. Mangrove DNA was found to give rise to a broad fluorescence and its integrated fluorescence intensity was enhanced on addition of As (V) and As (III), respectively. Analyses of the fluorescence parameter showed adequacy of 1:1 model to describe substitution of phosphate of mangrove DNA chain exiplex by arsenate and arsenite with equilibrium constant (log Kc) ranging between 4.19 and 4.32 for As (V), and between 3.77 and 3.89 for As (III) at pH 7 and 25°C. In the cases, the melting temperature (Tm) and reassociation rate constant of mangrove DNA was increased on treatment with As (V) and As (III). It is suggested that heavier ion arsenate and arsenite may substitute phosphate in natural DNA. © 2014 Springer Science+Business Media New York.

Bulletin of Environmental Contamination and Toxicology

Quantitative study of as (V) and as (III) interaction with mangrove DNA by molecular fluorescence spectroscopy

This study relates the abundance of foraminifera with the fluctuations in hydrobiological characteristics generated by the monsoonal cycle in a tropical mangrove ecosystem. Monthly variation of physicochemical properties of water and sediment, phytoplankton production, foraminiferal assemblages were measured in the littoral zone of the Sundarbans mangrove forest. Intra-annual variation of foraminifera exhibited a maximum abundance during the post-monsoon period and out of the 25 genera, numbers of calcareous and agglutinated forms were 16 and 9, respectively. Live benthic foraminifera were found to inhabit a wide range of sediment depths and inhabiting a high energy environment their abundance was not restricted to the uppermost centimeter. Owing to mechanical damage (due to high energy system), chemical dissolution and intense bioturbation, the taphonomic processes in this mangrove swamp could result in the destruction of the small size fraction of foraminifera, including agglutinated tests. The low numbers of agglutinated foram could be due to silty clay substrate. Abundance of more calcareous dead specimens over live ones could be attributed to predation and transportation of dead marine species.Most of the marine species could not survive in this freshwater dominated system. Anthropogenic nutrient input and diatombloomin association with enhanced food to benthos are important controlling factors on foraminiferal abundance and composition. © Society of Wetland Scientists 2012.

Wetlands

Intra-annual variation of modern foraminiferal assemblage in a tropical mangrove ecosystem in India

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 &amp; 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 &amp; V) following the Langmuir relation. Estimates of the maximum adsorption capacity are 59.11 ± 13.26 μg g -1 for As(III) and 58.45 ± 8.75 μg g -1 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. © 2011 Springer-Verlag.

Journal	Data powered by TypesetMarine Pollution Bulletin
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ISSN	0025-326X