AOGS-AGU (WPGM) JOINT ASSEMBLY,2012
International Conference,Singapore 13-17th August 2012.
Sanjay Kumar MANDAL1#+, Tapan Kumar JANA1
1University of Calcutta, India
#Corresponding author: mandal.sanjaykumar@gmail.com +Presenter
This study reports the measurement of stability constant for the interaction of As (V and III) and Sb (V and III) with humic substances extracted from Sundarban mangrove sediment, India. It was observed that As & Sb formed a more stable association with fulvic acid (FA) than its counterpart humic acid (HA), but the difference of stability with respect to oxidation state of As and Sb were less prominent. Quenching of fluorescence at increasing As (III & V) / Sb (III & V): FA /HA ratio was obtained that ideally correspond to one type of binding site (1:1 complexation model). Quite strong complexation of As & Sb (logarithm of the conditional stability constant between 5.13-5.68) by FA & HA occurs at neutral pH (7) indicating that HA & FA probably affect markedly the mobility of As & Sb in the mangrove environment. The sediment is silty clay loam type with 5.93% clay. FA and HA show excitation at 313 and 392 nm with the occurrence of maximum emission at 425 and 484 nm, respectively. This suggests that humification results in the shifting of λem (emission max.) towards longer wavelength (lower energy), which can be related to an increase aromatic condensation. The synchronous fluorescence spectra (SyF) of HA and FA are observed for FA at 346, 386 and 420nm and those for HA at 347, 394, 425 and 445nm.
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