Vol. 9 | No. 3 |424 - 430 | July - September | 2016 ISSN: 0974-1496 | e-ISSN: 0976-0083 | CODEN: RJCABP http://www.rasayanjournal.com http://www.rasayanjournal.co.in LAGOON SEDIMENTS IN PULICAT LAKE B. P. Dass Batvari and V.E. N. Mariappan GRAIN SIZE AND SEDIMENT CHARACTERIZATION OF LAGOON SEDIMENTS IN PULICAT LAKE, NORTH CHENNAI COASTAL REGION, SOUTH EAST COAST OF INDIA B. Prabhu Dass Batvari 1, * and V.E. Nethaji Mariappan 2 1 Center for Earth and Atmospheric Science, Sathyabama University, Jeppiaar Nagar, Rajiv Gandhi Road, Chennai-600119, India 2 Centre for Remote Sensing and Geoinformatics, Sathyabama University, Jeppiaar Nagar, Rajiv Gandhi Road, Chennai-600119, India *E-mail: batvarib@gmail.com ABSTRACT We presenting the results from a detailed study based on thirty three sediment samples were collected from Pulicat Lake during two seasons. The sand, silt and clay ration varies accordingly during premonsoon and post monsoon with variables at difference stations being observed. The maximum percentage of sand (95.85%) were seen near the bar mouth (Station 1) of Pulicat Lake with the average of 16.07% and 35.91% during post monsoon and premonsoon respectively. Silt percentage (average 14.55%) shows an increasing trend towards middle of the lake with maximum value at station 32. The clay content of sediments varies with the maximum values at station 18, 20 and 21 being minimum at 1, 2, and 3. This implies that the clay content shows an increasing trend towards the middle of the lake. The average value during premonsoon were 1.41% in comparison to post monsoon were 3.01%. The highest value were recorded at station 8 (4.10%), middle of the Lake during premonsoon with a minimum level at station 19 (0.20%). Keywords: Lagoon, grain size, Sediment, Pulicat Lake © RASĀYAN. All rights reserved INTRODUCTION Sediments play a significant role in aquatic systems and act as storage reservoirs for all kinds of pollutants which are introduced in to the aquatic ecosystem either by man or natural processes. Sediment consists of particles of varying sizes, shape and chemical composition, and are transported through different natural agencies and deposited according to their textural properties in different areas such as s and Seas 1 . Sediments (both estuarine and marine) usually act as sinks of river borne metals released through weathering and human activities in terrestrial environments 2-8 . The study of sediments and the distribution of metals in the sediments are more essential from the point of view of environmental pollution because sediment concentrates metals from aquatic systems, and represents an appropriate standard to monitor contamination 9 . The grain size, organic-matter and calcium carbonate content may be serious factors other than pollution that influence metal distributions in sediments 4,10 . Bottom sediments consist of particles have been transported by water, glaciers or air from the sites of their origin in a terrestrial ecosystem and have been deposited on the floor of a lake, river or ocean. In addition to these particles, bottom soil will contain materials precipitated from biological and chemical processes. Natural processes responsible for the formation of bottom sediments can be changed by anthropogenic influence. Many man-made materials have entered bodies of water through runoff from land, atmospheric deposition or direct discharge into the water. Most hydrophobic organic contaminants, metal composites, and nutrients, which enter into the water, become associated with particulate matter. Under certain situation the contaminants in the bottom sediments may be released back into the water or enter the food chain. Therefore, bottom sediments are a sink as well as a source of pollutant in the aquatic