Organic carbon in the sediments of Mandovi estuary, Goa

221-222Total organic carbon (TOC) in surficial sediments in Mandovi estuary varies widely from 0.1 to 3% (av. 1.05%). Highest values of TOC (2.4-3%) lie close to the mouth region and indicate no definite trend in its variation in the estuarine region. The values of TOC tend to decrease significantly in the upstream during major part of the year. Seasonal variation shows high TOC (av. 1.22%) in the estuary during premonsoon and low during monsoon (av. 0.94%) and the postmonsoon (av. 0.95%). During monsoon, spatial variation shows increasing values of TOC in the upper reaches of the estuary. Sewage discharges, primary production and land derived material are considered to be the source of organic carbon