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total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, which included ancillary samples taken from the high elevation area. Redox processes were investigated in the soil as well as groundwater in the shallow groundwater aquifer of Manukan Island, Sabah, Malaysia. Groundwater samples ( n = 10) from each boreholes were also collected in the low lying area to understand the concentrations and behaviors of Fe and Mn in the dissolved state. This study strives to obtain a general understanding of the stability behaviors on Fe and Mn at the upper unsaturated and the lower-saturated soil horizons in the low lying area of Manukan Island as these elements usually play a major role in the redox chemistry of the shallow groundwater. Thermodynamic calculations using PHREEQC showed that the groundwater samples in the study area are oversaturated with respect to goethite, hematite, Fe(OH) and undersaturated with respect to manganite and pyrochroite. Low concentrations of Fe and Mn in the groundwater might be probably due to the lack of minerals of iron and manganese oxides, which exist in the sandy aquifer. In fact, high organic matters that present in the unsaturated horizon are believed to be responsible for the high Mn content in the soil. It was observed that the soil samples collected from high elevation area (BK) comprises considerable amount of Fe in both unsaturated (6675.87 mg/kg) and saturated horizons (31440.49 mg/kg) compared to the low Fe content in the low lying area. Based on the stability diagram, the groundwater composition lies within the stability field for Mn and Fe under suboxic condition and very close to the FeS/Fe stability boundary. This study also shows that both pH and Eh values comprise a strong negative value thus suggesting that the redox potential is inversely dependent on the changes of pH. [ABSTRACT FROM AUTHOR]

Abstract: The world has been relying on fossil fuels as its primary source of energy. This unsustainable energy source is not going to last long and thus, gradual shift towards green renewable energy should be practiced. In Malaysia, even though fossil fuel dominates the energy production, renewable energies such as hydropower and biomass are gaining popularity due to the implementation of energy policies and greater understanding on the importance of green energy. Malaysia has been well endowed with natural resources in areas such as agriculture and forestry. Thus, with the availability of feedstock, biomass energy is practical to be conducted and oil palm topped the ranking as biomass source here because of its high production. However, new sources should be sought after as to avoid the over dependency on a single source. Hence, other agriculture biomass should be considered such as banana plant biomass. This paper will discuss on its potential as a new biomass source in Malaysia. Banana plant is chosen as the subject due to its availability, high growth rates, carbon neutrality and the fact that it bears fruit only once a lifetime. Conversion of the biomass to energy can be done via combustion, supercritical water gasification and digestion to produce thermal energy and biogas. The theoretical potential power generation calculated reached maximum of 950MW meeting more than half of the renewable energy requirement in the Fifth Fuel Policy (Eighth Malaysia Plan 2001–2005). Thus, banana biomass is feasible as a source of renewable energy in Malaysia and also other similar tropical countries in the world. [Copyright &y& Elsevier]