Sains Malaysiana 37(4): 299-305(2008) 

Diagenesis of Fatty Acids in Conwy Estuary, United Kingdom

(Diagnesis Asid Lemak di Muara Conwy, United Kingdom)

 

 

Masni Mohd Ali

School of Environmental and Natural Resource Sciences

Faculty of Science and Technology, Universiti Kebangsaan Malaysia

43600 Bangi Selangor, Malaysia

 

Stephen M. Mudge

School of Ocean Sciences, University of Wales, Bangor

Menai Bridge, Anglesey LL59 5AB

United Kingdom

 

Received:  1 April 2007 / Accepted:  12 February 2008

ABSTRACT

Thirty two compounds of fatty acids were found in a 50 cm sediment core taken from Conwy Estuary, United Kingdom. Their distribution pattern changed with depth from short chain fatty acids (C₁₂ - C₂₀) predominance to long chain compounds (C₂₁ – C₂₅). The decrease of short chain fatty acids along the core suggested that early diagenesis occurred due to microbial and chemical degradation. The increase of longer chain compounds was probably caused by greater preservation or greater contribution from terrestrial organic matter.  The percentage of branched fatty acids, odd/even and 18:1ω7/18:0 ratios showed similar distribution, linking them with bacterial activity in the sediment. Principal Component Analysis (PCA) separated the terrestrial derived fatty acids (long chain compounds) from the marine (short chain saturated compounds, mono and polyunsaturated fatty acids) and bacterial (odd chain length with their branched derivatives and 18:1ω7 acid) derived compounds.

 

Keywords: Conwy Estuary; fatty acids; diagenesis; PCA

 

 

ABSTRAK

 

Tiga puluh dua sebatian asid lemak telah dijumpai di dalam  teras sedimen 50 cm yang di ambil dari muara Conwy, United Kingdom. Pola taburan asid lemak berubah dengan kedalaman daripada asid lemak berantai pendek (C₁₂ - C₂₀) kepada sebatian-sebatian berantai panjang (C₂₁ – C₂₅). Pengurangan asid lemak berantai pendek di sepanjang teras mencadangkan diagenesis awal berlaku disebabkan oleh tindak balas mikrob dan kimia. Peningkatan sebatian-sebatian dengan rantai yang lebih panjang kemungkinan disebabkan oleh pengawetan atau sumbangan daripada bahan organik terestrial. Peratus asid lemak bercabang, nisbah rantai ganjil/rantai genap dan  nisbah 18:1ω7/18:0 menunjukkan taburan yang serupa, seterusnya mengaitkan mereka dengan aktiviti bakteria di dalam sedimen. Analisis Komponen Utama (PCA) dapat memisahkan asid lemak yang berasal dari terestrial (sebatian dengan rantai panjang) daripada asid lemak yang berasal dari persekitaran marin (sebatian-sebatian tepu berantai pendek, asid lemak mono dan politaktepu) dan asid lemak daripada bakteria (asid lemak dengan bilangan ganjil beserta dengan terbitannya dan asid 18:1ω7).

 

Kata kunci: Asid Lemak; Estuari Conwy; PCA; Diagenesis

 

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