Mohd Harun Abdullah

Controlling factors of groundwater hydrochemistry in a small island's aquifer

Factor analysis was applied to the hydrochemical data set of Manukan Island in order to extract the principal factors corresponding to the different sources of variation in the hydrochemistry. The application of varimax rotation was to ensure the clear definition of the main sources of variation in the hydrochemistry. The geochemical data of dissolved major, minor and trace constituents in the groundwater samples indicates the main processes responsible for the geochemistry evolution. By using Kaiser normalization, principal factors were extracted from the data for each location. The analysis reveals that there are four sources of solutes: (1) seawater intrusion; (2) leaching process of underlying rock mediated by pH; (3) minerals weathering process and (4) dissolution of carbonate minerals characterized by high loadings of Ca, Zn and Mg. Such processes are dominated by the significant role of anthropogenic impact from the over abstraction of fresh water from the aquifer. Those factors contributed to the changes of the groundwater geochemistry behavior explain the effect of rising extraction of freshwater from the aquifer.

Multivariate and Geoaccumulation Index Evaluation in Mangrove Surface Sediment of Mengkabong Lagoon, Sabah

Spatial variations in estuarine intertidal sediment have been often related to such environmental variables as salinity, sediment types, heavy metals and base cations. However, there have been few attempts to investigate the difference condition between high and low tides relationships and to predict their likely responses in an estuarine environment. This paper investigates the linkages between environmental variables and tides of estuarine intertidal sediment in order to provide a basis for describing the effect of tides in the Mengkabong lagoon, Sabah. Multivariate statistical technique, principal components analysis (PCA) was employed to better interpret information about the sediment and its controlling factors in the intertidal zone. The calculation of Geoaccumulation Index (Igeo) suggests the Mengkabong mangrove sediments are having background concentrations for Al, Cu, Fe, and Zn and unpolluted for Pb. Extra efforts should therefore pay attention to understand the mechanisms and quantification of different pathways of exchange within and between intertidal zones.

The Influence of Seawater on the Chemical Composition of Groundwater in a Small Island: The Example of Manukan Island, East Malaysia

Abstract ARIS, A.Z.; PRAVEENA, S.M., and Abdullah M.H., 2012. The influence of seawater on the chemical composition of groundwater in a small island: the example of Manukan Island, East Malaysia. Manukan Island in Sabah, Malaysia, is characterized as a small, unique island where groundwater is a major source for domestic water and other water-related activities. Hydrochemical studies were carried out in the island with the objective of identifying the influence of seawater on the chemical composition of groundwater in Manukan Island via ionic ratios and saturation states. From the calculated ionic ratios, the chemical composition of groundwater in the study area in general is influenced by seawater intrusion. The Na/Cl ratios ranged from 0.10–2.70, implying that the fresh groundwater in Manukan Island was affected by the seawater signature. Values close to ratio of seawater indicate a recent intrusion of seawater into the aquifer. Saturation index values show that the cation exchange process is found to control the concentration of calcium, magnesium, and sodium in the groundwater by precipitation of carbonate minerals as an extended effect from the mixing of seawater and fresh groundwater from its aquifer. The findings show that even though the Manukan Island aquifer is surrounded by seawater and is vulnerable to seawater intrusion attributed to its physical characteristics, it is also heavily affected by human activity related to groundwater abstraction. The data clearly indicate that seawater intrusion is the main contributor to salinity enrichment in the study area.

Efficient removal of transition metal ions using poly(amidoxime) ligand from polymer grafted kenaf cellulose

A desired copolymer, cellulose-graft-polyacrylonitrile was synthesized by a free radical initiating process and optimum reaction conditions were determined for maximum grafting yield (125%). The nitrile functionalities of the grafted copolymers were converted into the amidoxime ligand by oximation reaction. The kenaf cellulose, cellulose grafted copolymer and poly(amidoxime) ligand were characterized by infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The pH of the solution acts as a key factor to achieve the optical detection of metal ions using complexation of this ligand with some transition metal ions. The reflectance spectra of the [M–ligand]n+ complex was found to have a highest absorbance ranging from 97 to 99.9% at pH 6. The reflectance spectra were increased by increasing Cu2+ ion concentration and a broad peak at 700 nm was observed which indicates the charge transfer (π–π transition) complex. The adsorption capacity with copper was found to be superior; 326.6 mg g−1. The adsorption capacities for other transition metal ions were also found to be strong; Fe3+, Co3+, Mn2+, Cr3+, Ni2+ and Zn2+ were 273.6, 271.6, 241.7, 228.2, 204.2 and 224.3 mg g−1, respectively at pH 6. The experimental data of all metal ions fitted significantly with the pseudo-second-order rate equation. The data proved that the transition metal ion sorption onto ligands was well fitted with the Langmuir isotherm model (R2 > 0.99), which suggest that the cellulose-based adsorbent known as poly(amidoxime) ligand surface is homogenous and monolayer. The reusability was checked by the sorption/desorption process for seven cycles and the sorption and extraction efficiency in each cycle was determined. The new type of adsorbent can be reused in many cycles without any significant loss in its original sensing and removal performances.

Polycyclic Aromatic Hydrocarbons and Hopane in Malacca Coastal Water: 130 Years of Evidence for Their Land-Based Sources

Massive development over the past century has led to environmental oil-related pollution around the Malaysian city of Malacca. To characterize the concentration, sources, and origins of polycyclic aromatic hydrocarbons in Malacca’s coastal water in the Strait of Malacca, sediment cores from near shore and offshore were collected and analyzed. The highest concentration of total polycyclic aromatic hydrocarbons (PAHs) in the Near Shore station core was 4447 ng/g dry weight (dw) (1963–1969), and the lowest was 177 ng/g dw (1949–1955). The lowest concentration of PAHs in the Near Shore sample was 452 ng/g dw (1991 to 1997). In general, the Offshore core showed lower concentrations of total PAHs than did the Near Shore core, ranging from 1.71 (1914–1920) to 714.37 ng/g dw (1963–1969). Diagnostic tools such as specific compound, isomer ratio, and hopane characteristics indicate pollution by petroleum and combustion of oils from Southeast Asia and the Middle East in the study area since the1940s.

Modeling of Water Balance Components in a Small Island via a Numerical Model Application

Abstract PRAVEENA, S.M.; ABDULLAH, M.H.; BIDIN, K., and ARIS, A.Z., 2012. Modeling of water balance components in a small island via a numerical model application. A numerical model (SEAWAT-2000) was selected to estimate the water balance components in the low-lying area of Manukan Island. The water balance components of the current situation have shown that decreasing freshwater storage is due to irregularities in the patterns of recharge rate and overpumping. Scenarios 1 and 2 were selected for factors that affect the water balance components in the current situation. The water balance components in Scenarios 1 and 2 have illustrated sustainable management and utilization of groundwater resources in the study area. A valuable tool to restore groundwater storage has been demonstrated in Scenario 2, which represents the impact of future El Niño events. The best artificial recharge method must be selected with consideration given to other important factors. Extra meteorological and water usage data will aid sustainable management and utilization of groundwater resources, as well as further reduction of the pumping rate. The results of this study provide a management foundation for restoration of the groundwater resources of Manukan Island. The management foundation can also be used with other small islands that have similar hydrogeological conditions for the purpose of groundwater resource protection.

Modeling of seawater intrusion for a small tropical island aquifer in East Malaysia

This paper provides a numerical modeling output in Manukan Island aquifer using numerical model, . The modeling output showed that the low lying area of Manukan Island has been affected by seawater intrusion. The upcoming process is taking place beneath the pumping well and is attributed to seawater intrusion occurring in the low lying area of Manukan Island. There was about 14.5% of fresh-water and seawater mixing ratio in the low lying area of Manukan Island. Simulation output provided by this work using numerical model (SEAWAT-2000) can be used by local water management authorities in this case (Sabah Parks authorities), to understand the seawater intrusion in Manukan Island. The modeling output of this study is a foundation to formulate the optimal strategies for mitigation of possible future saline groundwater contamination through management and planning.

Numerical simulation of seawater intrusion in Manukan Island, East Malaysia

Purpose – This paper aims to define the current and potential extent of seawater intrusion in Manukan Island under different scenarios of varying recharge and pumping rates. The calibrated model was also used to predict the extent of seawater intrusion in low lying area of Manukan Island for two years with all conditions assumed to remain the same as those in December 2009.Design/methodology/approach – Different scenarios of varying recharge and pumping rates based on threats received by Manukan Island were investigated. El‐Nino events and overpumping are represented by varying recharge and pumping rates. Simulation was done using SEAWAT‐2000, the latest modeling software available in groundwater modeling that couples flow and transport together.Findings – The seawater‐freshwater mixing ratio moves landwards after two years of simulation in Scenario 1. In order to control overpumping in this study area, Scenario 2 has resulted in backward movement of the 1.4 percent seawater‐freshwater mixing ratio toward...

Quarter-Sweep Arithmetic Mean Algorithm for water quality model

In the previous studies, approximate solutions of water quality model were calculated by half-sweep arithmetic mean (HSAM) and half-sweep geometric mean (HSGM) methods using the HSCN finite difference scheme. Based on the CN finite difference scheme, however, we investigate application of the quarter-sweep arithmetic mean (QSAM) method in assessing the water quality model. In this paper, the formulation of the FSAM, HSAM and QSAM needs will be presented. Finally, results on numerical experiments conducted validate that the QSAM method has been shown to be very fast as compared to the FSAM and HSAM methods.

Distance approximation using pivot point in narrow phase collision detection

Discrete and Continuous Collision Detection is two common fields in Collision Detection research area where it helps to determine time and point of contact when two object intersect. Each technique increase speed and accuracy of the simulation itself but depending on application, we need to have specific solution of collision detection technique. Most computer games and simulation maintain speed as the main important elements while others such as medical and mechanical simulation needs to have a very high precision collision detection technique. Thus, an algorithm for the optimal distance computation algorithm for continuous collision detection is shown in this paper. The basic idea is to use an AABB for both object triangles and creating a moveable origin point called Dynamic Origin Point (DyOP). DyOP created by using minimum and maximum point of both AABBs where it dynamically changes whenever the object move. This is a novel algorithm that works better than the previously known Gilbert Keerthi-Johnson algorithm and Lin-Canny algorithm where it helps to reduce the complicated test and implementation. We have shown that our technique is performed faster than the previous algorithms by increasing speed and nearly approximate the good distance between two nearly intersected triangles.