Bottom sediments of Pulicat Lake, east coast of India

Abstract

Bottom sediment samples collected from the Pulicat Lake, a coastal lagoon on the east coast of India, have been subjected to mechanical and chemical analysis. Silt clay covers a major part of the lake followed by sand clay, clay sand and sand-silt-clay. The channel portion near the inlet and the wave-active marginal areas of the lake constitute mainly of sand. Phimean size and standard deviation show increasing trends from shore to the relatively quiet central part. The variation in the textural characteristics of the lake sediments is interpreted as resulting from varying degrees of mixing between an earlier deposited sand and modern silt and clay. Organic matter content of the sediments is in general low and the distribution pattern is inversely related to the mean grain size. The peripheral areas of the lake bottom have the least carbonate content (less than 5%). Sand clay and clay type sediments in the central part of the eastern lagoon are rich in carbonate.