Integrated geoelectrical resistivity and hydrogeochemical methods for delineating and mapping heavy metal zone in aquifer system

A novel study on using geoelectrical resistivity, soil property, and hydrogeochemical analysis methods for delineating and mapping of heavy metal in aquifer system is presented in this paper. A total of 47 surveys of geoelectrical resistivity with Wenner configuration were conducted to determine the subsurface and the groundwater characteristics. The groundwater sample from 53 existing wells and 2 new wells has been analyzed to derive their water chemical content. The chemical analysis was done on the soil sample obtained from new two wells and from selected locations. The water and soil chemical analysis results from the new two wells were used as calibration in resistivity interpretation. The occurrence of heavy metal in aquifer system was expected to detect using the geoelectrical resistivity survey for the whole study area. The result of groundwater analysis shows that the groundwater sample contains a relatively low concentration of Fe (<?0.3 mg/L) elongating from the south up to the middle region. While in the middle and the northwestern, Fe concentration is relatively high (around 12 mg/L). Chemical analysis of soil sample shows that in the lower resistivity zone (<?18 Ωm), Al and Fe concentrations are comparatively high with an average of 68,000 and 40,000 mg/kg, respectively. Starting from the middle to the northwestern zone, the resistivity value appears to be low. It is definitely caused by higher Al and Fe concentration within the soil, and it is supported also by lower total anion content in the groundwater. While the resistivity value of more than 40 Ωm in aquifers is obtained in the zone which Fe concentration is relatively lower in the soil but not present in the groundwater. Correlation Fe concentration in the soil and Fe concentration in the groundwater sample shows the trend of positively linear; however, the Al concentration in soil has no correlation with Al content in groundwater. Finally, the probability of high heavy metal zone in the aquifer system is easily delineated by the distribution of geoelectrical resistivity presented in depth slice shapes which extend from the Boundary Range Composite Batholith in the north to the northwest.     

Analytic network process for criteria selection in sustainable coastal land use planning

The coastal lands are very important boundaries in the natural system. But these areas are under pressure that has threatened their health by short-sighted planning policies. The management options have focused on economic production and human benefits rather than the natural systems that guaranty sustainability of them. Evaluation of sustainability in coastal lands needs some critical criteria and indicators. The purpose of this paper is to demonstrate an innovative reliable method for identification of the most important criteria and indicators using multi criteria techniques, especially the Analytic Network Process (ANP). Analytic Network Process as a new approach has potential to be applied into the field of coastal land use development. This is the first time ANP has been used for criteria selection to ensure sustainability in coastal land use planning. The integration of social, economic and environmental criteria within the planning framework in this paper has provided a holistic approach for integrated coastal land use development.     

Effect of loading rate on the volume change behavior of unsaturated residual soil

Residual soils occur in most countries of the world but those that occur in greater area and depth are usually found in the tropical humid areas. This research examines the effects of loading rate of applied or net mean stress on the volume change behavior of an unsaturated granitic residual soil. Three loading rates were adopted: fast, slow and extra slow loading rate. It was observed that the loading rate of applied or net mean stress has a pronounced effect on the void ratio and degree of saturation but has an insignificant effect on the water content of residual soils subjected to constant matric suction.     

Characterization of a Malaysian mangrove estuary

The Sungai Merbok estuary, in wet tropical Peninsular Malaysia, borders the Straits of Malacca. Tide, current, and salinity data are used to describe the salient hydrographic features of the mangrove-fringed system. The Sungai Merbok estuary is characterized by a 1.7 m semidiurnal tide with a 0.16 form number, peak currents of 1.3 m s^?1, and mean freshwater discharge of 20 m³ s^?1. The system is classified as 2a/2b estuary (Hansen and Rattray 1966) or 1a/1b during periods of low runoff. Gravitational circulation is highly variable (but coincides with the neap stratification) and vertical stratification varies from 10^?2 to 1. The estuary displays a pronounced fortnightly neap-spring stratification-destratification cycle. The effective longitudinal dispersion coefficient is approximately 100 m² s^?1.     

Contribution of the Root to Slope Stability

Land sliding is a geotechnical event that includes a wide range of ground movements such as rockfalls, deep failure of slopes and shallow debris flows, and it can cause various problems in varied civil fields such as roads and dams. Since most conventional methods are neither inexpensive nor applicable everywhere, attention has nowadays been drawn to soil bioengineering using vegetation as the environment-friendly method for slope stabilization. Soil bioengineering or using vegetation in civil engineering design is mostly applicable to shallow slope stabilization projects characterized by unstable slopes with surface movement. Vegetation has both a silent effect on soil improvement to predict the landslide and a mechanical role to increase shear and pulling-out stress on the soil. During the last decade, many researches have been carried out to clarify the effect of vegetation on slope stability, but many questions still remain to be answered.     

Visibility and Incidence of Respiratory Diseases During the 1998 Haze Episode in Brunei Darussalam

— Air pollution episodes as a result of forest fires in Brunei Darussalam and neighbouring regions have reached hazardous levels in recent years. Such episodes are generally associated with poor visibility and air quality conditions. In the present study, data on PM₁₀ (particulate matter of size less than 10 microns) and CO in Brunei Darussalam have been considered to study the incidence of respiratory diseases whereas data on relative humidity (RH) in addition to PM₁₀ have been used to explain the visibility with a particular emphasis on haze episode during 1998.¶Initial exploratory analysis indicates significant correlation of visibility with PM₁₀ and RH. An attempt has been made to explain visibility on the basis of PM₁₀ and RH using multiple linear regression analysis. The regression model shows that PM₁₀ and RH are two significant factors affecting the visibility at a given site. Further, canonical correlation, a multivariate method of analysis, has been used to explain the incidence of respiratory diseases as a function of air quality during the haze period. The results indicate that PM₁₀ and CO levels during the haze period have a significant bearing on the incidence of respiratory diseases (Asthma, Acute Respiratory Infections and Influenza (ARII)).     

Malaysian fisheries policy : Search for new grounds

Past fisheries development policies in Malaysia are assessed and new grounds for managing the Malaysian fisheries are explored. Some incompatibility in the goals for fishery development are discerned, especially those of increasing domestic landings through mechanization and resource conservation. Future management efforts should be based on a fuller understanding of the fishery stock and regional management of fish stocks. Aquaculture is often seen as a plausible alternative in order to augment supplies from the capture fisheries. A comprehensive multidisciplinary approach is needed to transform and commercialize traditional, experience-dependent culture systems into technology-packaged systems based on scientific methods. There is also substantial potential for the development of recreational fisheries.     

Resistivity methods in geothermal prospecting in Iceland

Resistivity techniques have been used successfully to identify and delineate geothermal resources in Iceland. The most frequently used techniques include Schlumberger, central loop TEM and head-on profiling. Geothermal systems in Iceland are located both within and outsite the active volcanic regions. Outsite the active volcanic regions the temperature in the upper most kilometer of the geothermal systems is below 150° C whereas the temperature in the geothermal fields within the active volcanic regions exceeds 200° C. The resistivity of the rock in geothermal fields located outside the active volcanic regions ranges from about 10 m to some hundreds of m, and are characterized by considerably lower resistivity than of the surrounding rocks. Most of the geothermal systems within the active volcanic regions, show common resistivity structure with low resistivity of 1–5 m surrounding an inner core of higher resistivity. This increasing resistivity with depth is associated with a change in the conduction mechanism, from interface conduction to electrolyte conduction due to a change in alteration minerals at about 240° C. Examples of resistivity surveys of geothermal fields from both outsite and within the active volcanic regions are discussed.     

Integrated geoelectrical resistivity,hydrochemical and soil property analysis methods to study shallow groundwater in the agriculture area,Machang, Malaysia

Integrated geoelectrical resistivity, hydrochemical and soil property analysis methods were used to study the groundwater characteristics of sandy soils within a shallow aquifer in the agriculture area, Machang. A pilot test investigation was done prior to the main investigation. The area was divided into two sites. Test-Site 1 is non-fertilized; Test-Site 2 is the former regularly fertilized site. From the surface to depths of 75 cm, a lower average resistivity was obtained in Test-Site 2 (around 0.37 less than in Test-Site 1). The presence of nitrate and chloride contents in pore water reduced the resistivity values despite the low moisture content. The pH values for the whole area range from 4.11 to 6.88, indicating that the groundwater is moderately to slightly acidic. In the southern region, concentration of nitrate is considered to be high (>20 mg/l), while it is nearly zero in the northern region. In the south, the soil properties are similar. However, the geoelectrical model shows lower resistivity values (around 18 Ω m) at the sites with relatively high nitrate concentration in the groundwater (>20 mg/l). Conversely, the sites with low nitrate concentration reveal the resistivity values to be higher (>35 Ω m). Basement and groundwater potential maps are generated from the interpolation of an interpreted resistivity model. The areas that possibly have nitrate-contaminated groundwater have been mapped along with groundwater flow patterns. The northern part of the area has an east to west groundwater flow pattern, making it impossible for contaminated water from the southern region to enter, despite the northern area having a lower elevation.     

Chemical composition of the Tertiary black shales of West Sabah, East Malaysia

The X-ray fluorescence and ICP methods were used to analyze 60 outcrop samples of black shale, of which 15 were collected from Belait, 15 from the Setap Shale, 15 from Temburong, and 15 from the Trusmadi formations. The average compositions of the shales from the study area are 64.62%, 63.95%, 62.32%, 63.84% SiO2, 1.84%, 2.14%, 2.04%, 1.99% MgO, 2.55%, 3.12%, 2.89%, 2.72% K2O, 0.32%, 0.30%, 0.32%, 0.53% CaO, 5.86%, 6.06%, 7.14%, 6.60% Fe2O3, 207×10^-6, 180×10^-6, 213×10^-6, 200×10^-6 Rb, and 56×10^-6, 49×10^-6, 50×10^-6, 32×10^-6 Sr for the Setap Shale, Temburong, Belait and Trusmadi samples, respectively. The high Rb/Sr ratios of 3.8, 3.7, 4.2, and 6.1 are attributed to the lowest contents of Sr due to reducing conditions prevailing. The high Rb/K ratio sug- gests either brackish marine or rapid deposition that prevented equilibrium between Rb and K in the shales and marine waters.