Summary of Abstract Submission

Abstract Submission No. IO50-08-0005PresentationPoster


R. Shynu*1, V. Purnachandra Rao1, Pratima M. Kessarkar1, S. W. A. Naqvi 1, P. K. Dineshkumar2

1 CSIR-National Institute of Oceanography, Goa, India
2 CSIR-National Institute of Oceanography, Regional Centre, Kochi, India


Time series measurements on suspended particulate matter (SPM) in and around mud bank regions of Alleppey, south west coast of India indicated extremely low SPM at surface and mid-depth waters (mean: <10 mg/l) and high SPM at bottom-depth waters (mean: 24.6 mg/l), during both the pre-monsoon and monsoon. Near bed SPM concentrations were high (6.2-9.2 g/l) during July and low (0.03┐0.1 g/l) during September in the mud bank region. An instrument, LISST-25X was used to measure the optical transmission (OT), particle volume concentration (PVC) and sauter mean diameter (SMD) of particles. OT was high (80-100%) at surface and mid-depth waters. Near bed waters of the mud banks include, 1 m thick fluid layer with 0% OT and a zone of high PVC (200-250 Ál/l) and low SMD (<25 Ám) particles during monsoon. Bottom sediments were clayey silts. The <63 Ám fractions of sediments were skewed towards coarser size and, sediment water content decreased and wet density increased in the mud bank region during monsoon. Our results indicated the occurrence of fluid muds at bottom waters in mud bank region and bottom sediment was found to be the source for fluid muds. As wave intensity is rigorous during the onset of monsoon, the dissipated high wave energy probably liquefied and eroded the sediment which was resuspended into the water column to form fluid muds. Upwelling may have been involved in the up keep and migration of fluid muds. The suspended muds resettled at the bottom soon after the monsoon event.