Assessment of toxicity level in selected heavy metals in volcanic soils from Tawau, Sabah

Heavy metals are one of the serious pollutants in environment because its toxicity. Severe concentration of heavy metals can harm the plants, animals and even human. During the pedogenesis process, heavy metals from the parent rock are mobilized in soils and redistribute in to the environment. The objective of this paper is to study the concentration and toxicity level of selected heavy metals in volcanic soils around Tawau, Sabah. In this study 10 soil samples were collected from different sampling stations. The selection of soil samples were based on the different type of volcanic rocks in the study area. The determination of concentration of heavy metals in soil samples were carried out using X-Ray Fluorescence (XRF) analysis. The result shows, the highest concentration is chromium with the average of 141 ppm followed by zinc with 112 ppm. The concentration of copper is 49 ppm, nickel 15 ppm, lead 8 ppm and arsenic 7 ppm. The soil samples is identified as polluted due to the elevated concentration of certain heavy metals when compared with the Sediment Quality Guidelines of US EPA. Chromium is regarded as heavily polluted agent while zinc, copper and arsenic indicated that the area is moderately polluted. Nickel and lead average concentration show no indication of pollution in the area. It is concluded that the combined source of heavy metals in the study area would be the parent materials of the soils and other anthropogenic effluent. From the study also, it is found out that pH value, organic matter and clay percentage has influenced the heavy metal concentration in volcanic soil in the study area

Effect of Moisture on Engineering Properties of Soil Slopes from Melange in Sandakan Sabah, Malaysia

A total of five soil samples were collected from mélange weathered material in order to analysis the effect of moisture on engineering properties of the soils. The soil samples were collected along the main road in Sandakan, Sabah. The result of analysis shows that the soil moisture content was in the range of 15.26% to 22.10%. The average liquid limit of soil samples was from 45.1% to 59.8%, while the plasticity indexes were in the range of 23.25% to 33.91%. The plasticity chart plot of soil found that S1 and S5 were classified as low plasticity soil, while S2, S3 and S4 soil were classified as high plasticity. The result shows that the optimum moisture contents ranged from 13.0% to 28.9%, while the maximum dry density is within a range from 1.43Mg/m3 to 1.82Mg/m3. The unconfined compression strength indicated that S3 is classified as very soft soil, S1 and S4 soft soil, S2 moderate soft soil and s5 strong soil. Additional of moisture above optimum content in to the soil resulted in lower strength for all soil samples, whereas higher strength value range were observed when the moisture content is reduced below the optimum content. As conclusion, additional moisture contents influenced the engineering properties of soil samples due to its high adsorption of water in clayey soil as identified from the XRD and SEM analysis