Distribution and sources of sedimentary organic matter in a tropical estuary, south west coast of India (Cochin estuary): A baseline study

作者：Gireeshkumar T R^*; Deepulal P M; Chandramohanakumar N

来源：Marine Pollution Bulletin, 2013, 66(1-2): 239-245.

DOI：10.1016/j.marpolbul.2012.10.002

• Geochemistry
• Total organic carbon
• Nitrogen
• Isotopes
• Estuaries

Surface sediments samples were collected from 9 stations of the Cochin estuary during the monsoon, post-monsoon and pre-monsoon seasons and were analyzed for grain size, total organic carbon (OC), total nitrogen (TN) and stable isotopic ratios of carbon (delta C-13) and nitrogen (delta N-15) to identify major sources of organic matter in surface sediments. Sediment grain size is found to be the key factor influencing the organic matter accumulation in surface sediments. The delta C-13 values ranges from -27.5 parts per thousand to -21.7 parts per thousand in surface sediments with a gradual increase from inner part of the estuary to the seaward side that suggest an increasing contribution of marine autogenous organic matter towards the seaward side. The delta N-15 value varies between 3.1 parts per thousand and 6.7 parts per thousand and it exhibits complex spatial and seasonal distributions in the study area. It is found that the dynamic cycling of nitrogen through various biogeochemical and organic matter degradation processes modifies the OC/TN ratios and delta N-15 to a considerable degree. The fraction of terrestrial organic matter in the total organic matter pool ranges from 13% to 74% in the surface sediments as estimated by delta C-13 based two end member mixing model.

• 出版日期2013-1-15