Sains Malaysiana 34(2): 23-33 (2005)

Lipid Geochemistry in a Sediment Core from

Conwy Estuary, North Wales

(Geokimia Lipid dalam Turus Sedimen daripada

Estuari Conwy di Utara Wales)

Masni Mohd Ali

School of Environmental and Natural Resource Sciences

Faculty of Science and Technology

Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E., Malaysia

Stephen M. Mudge

School of Ocean Sciences

University of Wales, Bangor

Menai Bridge, Anglesey LL59 5AB

United Kingdom

ABSTRACT

The sources and diagenesis of organic matter in sediment core from the Conwy Estuary, North Wales have been examined using lipid biomarker data (i.e. fatty alcohols and sterols). Twenty-five core sections were analysed from the surface to 50 cm depth. Sediments near the top of the core were enriched in marine organic matter with high concentration of short chain fatty alcohols and sterols, and decreased with depth. Terrestrial organic matter predominated the bottom sections of the core. These observations can be seen from the short/long ratio, Alcohol Source Index and Sterol Source Index, suggesting the degradation of the marine derived compounds. The sewage derived organic matter increased from bottom to top of the core showing the increasing input of sewage from the past until now. Multivariate statistical technique (PCA) was carried out to interpret the data. PCA confirmed above observations with PC1 and PC2 indicated biogeochemical sources.

Keywords: fatty alcohols, sterols, diagenesis, PCA

ABSTRAK

Sumber dan diagenesis bahan organik di dalam turus sedimen daripada estuari Conwy di Utara Wales telah dikaji menggunakan data penanda biologi lipid (seperti alkohol lemak dan sterol). Dua puluh lima bahagian dalam turus tersebut telah dianalisa bermula dari permukaan hinggalah ke kedalaman 50 cm. Sedimen di permukaan adalah kaya dengan bahan organik marin dengan kepekatan rantai pendek alkohol lemak dan sterol yang tinggi, dan berkurangan mengikut kedalaman. Bahan organik terestrial mendominasi bahagian bawah turus. Pemerhatian ini dapat dilihat daripada nisbah rantai pendek, rantai panjang, Indeks Sumber Alkohol dan Indeks Sumber Sterol. Pemerhatian ini juga menunjukkan degradasi sebatian marin. Bahan organik kumbahan pula meningkat daripada bahagian bawah ke bahagian atas turus menunjukkan penambahan input kumbahan daripada masa lalu hingga kini. Teknik statistik multivariat (PCA) telah digunakan untuk menginterpretasi data. Analisis Komponen Utama mengesahkan pemerhatian di atas dengan Komponen 1 dan Komponen 2 menunjukkan sumber biogeokimia.

Kata kunci: Alkohol lemah, sterol, diagenesis, analisis komponen utama  

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