Changing of manganese and total organic carbon in marine sediment core as a signal for marine productivity

Abstract

ABSTRACT

²¹⁰Pb dating, Mn and total organic carbon have been used in this study to determine the sedimentation rate and the productivity in coastal of Kelantan. Four sediment cores which are SF1, SF3, SF5 and SF7 were taken using the gravity corer on June 2008. The 125 µm dry sediment with particle mesh was used to determine the concentration of ²¹⁰Pb, Mn and total organic carbon.  Activity level of ²¹⁰Pb was determined using the Tennelec XLB-5 Gross Alpha-Beta Counter, Canberra, after the ingrowth of ²¹⁰Pb by the outgrowth of ²¹⁰Bi. While the content of Mn was measured using the Perkin Elmer SCIEX Inductively Coupled Plasma Mass Spectrometry ELAN 9000 technique and the organic carbon content was estimated using combustion method. The analysed result showed the ²¹⁰Pb activity for all samples were decreasing from top to the bottom sediment. While the vertical profile of Mn concentration had scattered distribution throughout the core sediments. However, Mn concentrations in the samples were lower than the Mn concentration in the earth crust that is 770.00 mg/kg. Values of the total organic carbon (TOC) content are higher in sites that are closer with land and lower in offshore sites. The value of sedimentation rate was 0.59 cm yr^-1, 0.47 cm yr^-1, 0.36 cm yr^-1 and 0.46 cm yr^-1 for SF1, SF3, SF5 and SF7, respectively. This indicates various sediment age ranges and year of accumulation of sediments. It shows that the organic carbon contents produced Mn²⁺ during anaerobic decomposition process in the sediment.

 ABSTRAk

Teknik penyurihan ²¹⁰Pb, Mn dan total organik telah digunakan dalam kajian ini untuk menentukan kadar pemendapan dan produktiviti di pantai Kelantan. Empat teras sedimen yang SF1, SF3, SF5 dan SF7 diambil menggunakan corer graviti pada bulan Jun 2008. Sedimen kering 125 μm dengan mesh zarah digunakan untuk menentukan kepekatan 210Pb, Mn dan jumlah karbon organik. Tahap aktiviti 210Pb ditentukan dengan menggunakan Tennelec XLB-5 Kaunter Alpha-Beta Kasar, Canberra, selepas penanaman 210Pb dengan hasil 210Bi. Walaupun kandungan Mn diukur menggunakan teknik Spekrometri Massal Plasma Perkin Elmer SCIEX yang Digabungkan ELAN 9000 dan kandungan karbon organik dianggarkan menggunakan kaedah pembakaran. Hasil analisa menunjukkan aktiviti 210Pb untuk semua sampel telah menurun dari sedimen bawah ke bahagian bawah. Sedangkan profil menegak kepekatan Mn telah menyebarkan pengedaran sepanjang sedimen teras. Walau bagaimanapun, kepekatan Mn dalam sampel adalah lebih rendah daripada kepekatan Mn dalam kerak bumi iaitu 770.00 mg / kg. Nilai kandungan karbon total (TOC) adalah lebih tinggi di tapak yang lebih dekat dengan tanah dan lebih rendah di tapak luar pesisir. Nilai kadar pemendapan ialah 0.59 cm yr-1, 0.47 cm yr-1, 0.36 cm yr-1 dan 0.46 cm yr-1 untuk SF1, SF3, SF5 dan SF7. Ini menunjukkan pelbagai rentang umur sedimen dan tahun pengumpulan sedimen. Ia menunjukkan bahawa kandungan karbon organik menghasilkan Mn2 + semasa proses penguraian anaerobik dalam sedimen.