Copper, Cobalt, Zinc, Phosphorous, Arsenic, Adsorption, mangrove sediment, Sundarbans

Adsorption kinetic control of As(III & V) mobilization and sequestration by Mangrove sediment

 S. K. Mandal • N. Majumder • C. Chowdhury •

 D. Ganguly • M. Dey • T. K. Jana

Environ Earth Sci, Springer,2011

DOI 10.1007/s12665-011-1183-9

Abstract:

Elevated concentrations of arsenic in the sediment and pore water in the Sundarban wetlands pose and 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 theadsorption of As(III & V) following the Langmuir relation. Estimates of the maximum adsorption capacity are59.11 ± 13.26 lg g-1 for As(III) and 58.45 ± 8.75 lg 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 porewater by the microbial oxidation of organic matter in the sediment with less feedback of adsorption

Cell Size versus Taxonomic Composition as Determinants of As (III & V) Sensitivity in the Estuarine Diatom Communities

 

Journal of Water Resource and Protection, 2011, 3, 363-369 doi:10.4236/jwarp.2011.36046 Published Online June 2011 (http://www.scirp.org/journal/jwarp) Copyright © 2011 SciRes. JWARP

 Cell Size versus Taxonomic Composition as Determinants of As (III & V) Sensitivity in the Estuarine Diatom Communities

Chumki Chowdhury, Natasha Majumder, Sanjay Kumar Mandal, Manab Kumar Dutta, Raghab Ray, Tapan Kumar Jana*

Department of Marine Science, Calcutta University, Kolkata, India

E-mail: tkjana@hotmail.com

Received March 15, 2011; revised April 17, 2011; accepted May 20, 2011

Abstract

Despite scarce studies have analyzed the relative growth inhibition of As (III) and As (V) to diatom, clear pattern of interspecies difference have been shown, identifying cell size as a key property determining the sensitivity of diatom to As. Evidence from cultures suggests that cell size is a key factor in determining the extent of arsenic (III) & (V) stress of diatom, with relatively lesser effects of As (V) than As (III) on small cells. Cent percent growth inhibition was observed for large size group (Coscinodiscus radiatus, Surirella., Amphipleura, Thalassiothrix, Cyclotella and Thalassiosira decipiens) relative to smaller size group (Skele-tonema cf. costatum, Navicula rhombica, Amphora hyalina Nitzschia longissima except Thalassisira. Inter-species differences in As tolerance by diatom in the mangrove ecosystem indicates cell size could be only one factor contributing to these differences. The results show that 81.7% of total arsenic was uptaken from culture media originally amended with arsenic. Looking to the extreme tolerance and arsenic removal effi-ciency, application of the species with smaller cell size relative to the other tested diatom for bioremediation purpose can be envisaged.

Keywords: Diatoms, Cell Size, Arsenic (III&V), Mangrove