Geochemistry, textural studies and its environmental implications on the core sediment of Kadalundi estuary, Kerala

1536-1544The study area Kadalundi estuary is fully occupied with mangroves, and conserved as a bird sanctuary. In this estuary, systematic studies on sedimentological and geochemical aspects are not done so far. Hence, an attempt has been made in this area to infer the paleoenvironmental significance in this region. A core of length 185 cm was taken and subsampled in 5 cm intervals. The sand-silt-clay analyses indicate higher concentration of sand in the core and overall low calcium carbonate content. The organic matter content is highly concentrated at the top and bottom core, whereas in the middle core it is slightly decreased. The sorting values depict poor sorting which indicates mixed environment condition.i.e, one derived from riverine/aeolian environment and the other derived from marine environment. This is due to the widely varying nature of sediments and change in gradients of the coastaline. The heavy mineral assemblage of the study area shows the distribution of low and high ranked metamorphic and some basic igneous rocks.The presence of a little amount of zircon in the top core implies the influence of marine inputs by reworked sediments. XRF data resembles a sudden rise in the concentration towards the bottom core suggests that the trace elements show a positive relation with silt, clay and organic matter in the sediments. XRD analysis projects the presence of Illite in all the samples suggesting the emergence of estuary into Arabian Sea and the reworking of waves. From the overall study it is concluded that the river discharge from Kadalundi, deposits an additional sub-population of sand with a mean size of sediments from medium to fine grained, where low-energy conditons prevails and accretionary processes are taking place with mixed environments