Distribution and nature of sedimentary organic matter in a tropical estuary: An indicator of human intervention on environment

Sediment texture controls the spatial distribution of sedimentary organic matter (SOM) in the Vembanad Lake. Influences of marine derived organic matter (OM) on SOM decreased inner-wards in the northern part of the lake. However, SOM from the southern part of the lake was dominated by terrestrial OM. Marine-derived OM showed the highest affinity for the clay-sized fraction (< 2 μm) of the sediment in the northern part of the lake. However, aged and humified soil-derived OM was predominant in the clay-sized fractions from the southern part. Alteration of sediment texture led to a change in the distribution pattern of SOM in the lake after bund construction. Human intervention and changes in land-use pattern were also found to influence the SOM content in the southern part of the lake.