Natural uranium and thorium isotopes in sediment cores off Malaysian ports

Abdul Hafidz Yusoff, Asnor Azrin Sabuti, Che Abd. Rahim Mohamed

Research output: Contribution to journalArticle

Abstract

Sediment cores collected from three Malaysian marine ports, namely, Kota Kinabalu, Labuan and Klang were analyzed to determine the radioactivities of <sup>234</sup>U, <sup>238</sup>U, <sup>230</sup>Th, <sup>232</sup>Th and total organic carbon (TOC) content. The objectives of this study were to determine the factors that control the activity of uranium isotopes and identify the possible origin of uranium and thorium in these areas. The activities of <sup>234</sup>U and <sup>238</sup>U show high positive correlation with TOC at the middle of sediment core from Kota Kinabalu port. This result suggests that activity of uranium at Kota Kinabalu port was influenced by organic carbon. The <sup>234</sup>U/<sup>238</sup>U value at the upper layer of Kota Kinabalu port was ≥1.14 while the ratio value at Labuan and Klang port was ≤ 1.14. These results suggest a reduction process occurred at Kota Kinabalu port where mobile U(VI) was converted to immobile U(IV) by organic carbon. Therefore, it can be concluded that the major input of uranium at Kota Kinabalu port is by sorptive uptake of authigenic uranium from the water column whereas the major inputs of uranium to Labuan and Klang port are of detrital origin. The ratio of <sup>230</sup>Th/<sup>232</sup>Th was used to estimate the origin of thorium. Low ratio value (lt; 1.5) at Labuan and Klang ports support the suggestion that thorium from both areas were come from detrital input while the high ratio (> 1.5) of <sup>230</sup>Th/<sup>232</sup>Th at Kota Kinabalu port suggest the anthropogenic input of <sup>230</sup>Th to this area. The source of <sup>230</sup>Th is probably from phosphate fertilizers used in the oil-palm cultivation in Kota Kinabalu that is adjacent to the Kota Kinabalu port.

Original languageEnglish
Pages (from-to)403-412
Number of pages10
JournalOcean Science Journal
Volume50
Issue number2
DOIs
Publication statusPublished - 22 Jun 2015

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thorium isotope
uranium isotope
sediment core
uranium
thorium
total organic carbon
organic carbon
radioactivity

Keywords

  • detrital
  • Kota Kinabalu port
  • sediment core
  • thorium
  • total organic carbon (TOC)
  • uranium

ASJC Scopus subject areas

  • Oceanography

Cite this

Natural uranium and thorium isotopes in sediment cores off Malaysian ports. / Yusoff, Abdul Hafidz; Sabuti, Asnor Azrin; Mohamed, Che Abd. Rahim.

In: Ocean Science Journal, Vol. 50, No. 2, 22.06.2015, p. 403-412.

Research output: Contribution to journalArticle

Yusoff, Abdul Hafidz ; Sabuti, Asnor Azrin ; Mohamed, Che Abd. Rahim. / Natural uranium and thorium isotopes in sediment cores off Malaysian ports. In: Ocean Science Journal. 2015 ; Vol. 50, No. 2. pp. 403-412.
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