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Distribution and sources of aliphatic hydrocarbons and fatty acids in surface sediments of a tropical estuary south west coast of India (Cochin estuary)

DRS at CSIR-National Institute of Oceanography

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Title Distribution and sources of aliphatic hydrocarbons and fatty acids in surface sediments of a tropical estuary south west coast of India (Cochin estuary)
 
Creator Gireeshkumar, T.R.
Deepulal, P.M.
Chandramohanakumar, N.
 
Subject Geographical distribution
Saturated hydrocarbons
Fatty acids
Sediment composition
Biomarkers
Organic constituents
 
Description Surface sediments samples from the Cochin estuary were measured for elemental, stable isotopic and molecular biomarkers (aliphatic hydrocarbons and fatty acids) to study the sources and distribution of sedimentary organic matter. Concentrations of total organic carbon (TOC), total nitrogen (TN) and stable isotopic ratios of carbon (delta 13C) ranged from 0.62 to 2.74 %, 0.09 to 0.25 % and -27.5 to 21.7‰, respectively. Sedimentary n-alkanes ranged from 6.03 to 43.23 mu g g-1 with an average of 16.79 mu g g-1, while total fatty acids varied from 22.55 to 440.69 mu g-1. The TOC/TN ratios and delta 13C suggest a mixture of marine- and terrestrial-derived organic matter in the surface sediments with increasing contributions from marine-derived organic matter towards the seaward side. Long-chain n-alkanes derived from higher plants predominated the inner part of the estuary, while short-chain n-alkanes derived from planktonic sources predominated the bar mouth region. The even carbon preference of the C12–C22 n-alkanes may refer to the direct biogenic contribution from bacteria, fungi and yeast species and to the potential direct petroleum inputs. The presence of odd mid-chain n-alkanes in the sediments indicates the organic matter inputs from submerged and floating macrophytes (water hyacinth). Various molecular indices such as carbon preference index, terrestrial to aquatic ratio, average chain length and the ratios of mid-chain n-alkanes support the aforementioned inferences. The high contribution of odd and branched chain fatty acids along with very low contribution of polyunsaturated fatty acids, suggest the effective utilisation of algae-derived organic matter by bacteria and the effective recycling of labile organic matter in whole settling and deposition processes. The distributional variability of n-alkanes and fatty acids reveals the preferential utilisation of marine-derived organic matter and the selective preservation of terrestrial-derived organic matter in surface sediments of the Cochin estuary
 
Date 2015-03-09T10:06:44Z
2015-03-09T10:06:44Z
2015
 
Type Journal Article
 
Identifier Environmental Monitoring and Assessment, vol.187; 2015; No.56 doi:10.1007/s10661-015-4308-x.
http://drs.nio.org/drs/handle/2264/4716
 
Language en
 
Rights An edited version of this paper was published by Springer. This paper is for R & D purpose and Copyright [2015] Springer
 
Publisher Springer