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Title:	Geochemistry of serpentinite and its effects on the environment: case study at peninsular and Sabah Malaysia
Authors:	Mahsa Tashakor (P54247)
Supervisor:	Wan Zuhairi Wan Yaacob, Dr.
Keywords:	Geochemistry of serpentinite Serpentinite effects Malaysia Sabah Peninsular Universiti Kebangsaan Malaysia -- Dissertations
Issue Date:	28-Mar-2014
Description:	The current study investigates whether serpentinite rocks and soils which pose specific geochemical features, notably their richness in some toxic heavy metals such as Cr, Ni and Co are able to influent the environment. A total number of four serpentinized-ultramafic outcrops in Peninsular Malaysia and one large serpentinite body in Sabah have been chosen as the study areas. They are located at Cheroh and Bentong in Pahang, Bukit Rokan and Petasih in Negeri Sembilan, and in Ranau, Sabah. A total of 13 rock, 30 soil, 27 river water and 4 underground water samples have been analysed by four groups of techniques, namely petrography, mineralogy, geochemistry and physico-chemistry. The petrographic study, which involves microscopic study using polarized microscope, X-ray diffraction (XRD) and scanning electron microscope (SEM), has proven that the source rock is serpentinite, and the soils are mainly made up of oxides and hydroxides of iron, notably goethite and hematite. Furthermore, all soils are constituted by magnetite, chromite and other mixed spinels, gibbsite and allochthonous quartz. The elemental distribution of minerals in rocks and soils were mapped by using Energy-Dispersive X-ray spectroscopy (EDX), attached to the SEM machine. Determination of the chemical composition of rock and soil samples by using X-ray fluorescence technique (XRF) has shown that in terms of natural soil pollution, Cr, Ni and Co in the analysed serpentinite soils exceed the optimum and action values given by Dutch List standard by the factor of 37 and 8 for Cr and Ni, respectively. However, against what was initially expected, all elements have concentrations below the INWQS standard limits, both in surface and drinking waters of the area. In order to explain the unexpected phenomena, some physical and chemical characteristics of soils were investigated, including particle size distribution, specific gravity and cation exchange capacity (CEC). The results of Toxicity characteristic leaching test (TCLP) have shown that despite hyperaccumulation of Cr, Ni and Co in serpentinite soils, they pose no toxicity to the environment. Speciation of heavy metals among different soil fractions was accomplished by using the selective sequential extraction (SSE) technique. SSE results revealed that the residual fraction of soil is the main pool for Cr and Ni. This is in agreement with the petrographic observation which attributes these metals to resistant silicates. Furthermore, association of Cr and Ni with crystalline Fe-oxide fraction proves the important role of goethite and hematite in immobilization of these elements in tropical serpentinite soils. On the other hand, availability of Co is mostly controls by Mn-Oxide and poor crystalline Fe-oxide. SSE analysis shows that none of the studied heavy metals is concentrated in soluble-exchangeable, surface adsorbed and organic matter fractions of the soils. Taken together, one can conclude that, even though Cr, Ni and Co in serpentinite soils occurs in elevated amounts, they are not a serious threat for the environment because of their low availability in the soil system. However, Co is slightly more mobile than Cr and Ni, probably because of its mineralogical host control.,PhD
Pages:	210
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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