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Serpentinite soils are characterised by high concentrations of chromium, nickel, and cobalt. The accumulation of heavy metals as non-degradable inorganic contaminants is of great concern. Under normal circumstances the form in which a metal exists governs its transport in the environment and thus, its hazards. In this study, a specific developed speciation analysis for tropical soils was applied to determine the mobility of Cr, Ni and Co in two serpentinitic soil outcrops in Malaysia. The combination of selective sequential extraction analysis (SEE) and X-ray diffraction of soil powders showed that Cr and Ni are primarily associated with the residual fraction of soil which is inherited from resistant silicates. The crystalline Fe-oxide fraction of soil is the second substanial scavenger of Cr and Ni, whilst the dynamics of Co are mostly controlled by Mn-oxide and the poor crystalline Fe-oxide. The more easily mobilised forms of the studied metals carried on soluble-exchangeable, surface adsorbed and organic matter fractions are of minimal compartments. Therefore these metals are basically not available in the environment. On the other hand, corroborating information on the mobility of the metals was gained by applying the toxicity characteristic leaching procedure test (TCLP). The consistent results of the TCLP with the SSE revealed the non-toxic effects of Cr, Ni and Co in the environment despite their overload accumulation in the analysed serpentinite soils.

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The unpleasant effect of serpentine soil on plant life has been a topic of many studies for several decades. Infertility and flora selectivity nature of serpentine soils are the features, which made them of interest throughout the world. This research includes a geochemical study on two Malaysian serpentine massifs to introduce their harmful factors concerning vegetation. X-ray fluorescence results on 11 soil samples showed that serpentine soils comprise large values of iron and magnesium (up to 55 wt and 65 wt% respectively) and high amounts of some heavy metals like chromium (1248-18990 µg g^-1), nickel (189-1692 µg g^-1) and cobalt (95-478 µg g^-1). However, soil extraction by ammonium acetate solution revealed that only magnesium is plant available. Besides, serpentine soils are poor in some major plant nutrients such as nitrogen, potassium and phosphorus. This substantial paucity is the main cause of bareness in these lands. Soils in the studied areas are moderately acidic and have the adequate cation holding capacity. Their Ca/Mg quotient is very low (less than 1). The latter with the low availability of the calcium (0.34 m-equiv 100 g^-1 in average) is another challenging parameter in serpentine soils, which exerts negative influence on plant growing

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