JOURNAL GEOLOGICAL SOCIETY OF INDIA Vol.80, September 2012, pp.429-434 0016-7622/2012-80-3-429/$ 1.00 © GEOL. SOC. INDIA Characterization of Clay Minerals in the Sundarban Mangroves River Sediments by SEM/EDS K. RAJKUMAR 1,2 , AL. RAMANATHAN 1 and P. N. BEHERA 2 1 School of Environmental Sciences, Jawaharlal Nehru University New Delhi - 110 067 2 Department of Geology, Utkal University, Vani Vihar, Bhubaneswar - 751 004 Email: phuvanraj@gmail.com Abstract: Clay minerals, byproducts of chemical weathering, are important group of minerals found in rivers, estuaries, and marine sedimentary environments, which include mudstones, clay stones, and shales. In the present study, FTIR and SEM investigation on the clay minerals in Sundarban mangrove core sediments collected from Moipith Matla and Belamati Island are carried out. The study indicated the dominant association of kaolinite with subordinate amount of quartz, illite and chlorite. The abundance of kaolinite, illite chlorite and clay with quartz helps in increasing sediment in the islands region. The geochemical and mineralogical evolution of mangrove sediments are results of the interaction of biotic and abiotic parameters, whose balance is conditioned by the climate that governs the hydrologic regime, the sedimentation dynamics and the organic matter. This study on the charaterstation of clay provides us with substantial impact in the water holding capacity, productivity and mineralogical and chemical transformation in order to establish much more and intermediate equilibrium between marine influence and continental contribution, as part of the estuarine environment, than to the tropical climate conditions. Keywords: Sundarban sediment, Clay minerals, FT-IR, SEM-EDS. INTRODUCTION Mangrove have been studied in many regions of the world not only because of their importance as source of food, but also for in depth understanding of this ecosystem. In Sundarban mangroves, studies are more recent and are mainly concentrated on the fauna and flora as well as anthropogenic impacts. Clay is composed mainly of silica, alumina and water, frequently with appreciable quantities of iron, alkali metals and alkaline earth earths (Nayak et al. 2007). Clay materials possess a layered structure and are classified by the differences in their layered structures. There are several classes of clays such as smectites (montomorillonite, saponite), mica (illite), kaolinite, serpentine, pylophyllite (talc), vermiculite and sepiolite (Shichi and Takagi, 2000). The adsorption capabilities result from a net negative charge on the structure of minerals. This negative charge gives clay the capability to adsorb positively charged species. Their sorption properties also come from their high surface area and high porosity (Alkan et al. 2004). Montomorillonite clay has the largest surface area and highest cation exchange capacity. The literature on quantitative clay mineral analysis has been reviewed from time to time. Ghosh and Kapoor (1982) and many others (Ramanathan et al. 1999; Prasad et al. 2005;) have revealed the occurrence of a wide spectrum of minerals. The FTIR study of water adsorption on TMA- and TMPA-montmorillonites was carried out by Stevens and Anderson (1996a). To understand the characterization of clay mineral component of the associated sediments of this river basin, as it has an intimate relationship with the engineering properties of the bank sediments in question, which, in turn, are related with the extent and nature of erosion mechanisms involved. The chemical characterizations of these sediments using FTIR and SEM are attempted for the first time in Sundarban mangroves ecosystem. EXPERIMENT Sundarban is an active delta/estuary of India and Bangladesh, formed by fluvial activity of Ganga and Brahmaputra river, at the mouth of Bay of Bengal. Its portion in India (West Bengal) is located between (latitudes 21°40'- 23°40' N and longitude 87°60'-89°20' E) with a network of tidal river channels, mudflats, sand flats, coastal dunes, creeks and islands. Sundarban tidal estuary comprises an