Mercury distribution in Port Klang mangrove and estuarine sediment

Mangrove and estuarine areas are important to the ecosystem and can act as a sink of pollutants, especially metal ions. However, the accumulation of metals in sediment can cause negative impacts on plant growth, microbial activity and soil fertility. The severity and nature of the impact is highly influenced by the type of metal found in the sediment. One of the metals that have adverse effects on the environment is mercury. Therefore, the objectives of this study are to determine the mercury concentration and its distribution in the study area. Sediment samples were collected from 30 sampling points that cover Langat River and Klang River estuaries, Lumut Straits, Pulau Klang and Pulau Indah in Selangor, Malaysia. The extractable mercury in sediment samples was determined at the laboratory using inductively coupled plasma mass spectrometry (ICP-MS). In this study, mercury was found to be concentrated along Lumut Strait especially in the mixing zone near the confluence of Langat River

A review of groundwater in islands using SWOT analysis

This paper has focused and reviewed the groundwater of 55 islands around the world using Strength, Weakness, Opportunities and Threats (SWOT) analyses selected based on existing literatures and studies conducted. The SWOT analysis output fills in the gap of scientific knowledge and helps in groundwater management. The overall of groundwater management in islands should be conducted by the highest government level. The institutional framework must make sure that any development and management of water resources in these islands take place in national level planning. The main thing is to ensure collaborations between agencies for sustainable management of groundwater in islands

Irrigation water quality assessment of a trans-state river basin in western part of Malaysia by integration of hydrochemical and chemometric analysis

This study aims to assess the monsoon effect on the chemical composition of water samples collected from Langat River, a trans-state river basin and to evaluate the suitability of the water for irrigation purposes. In-situ parameters (pH, salinity, electrical conductivity and total dissolved solids) and major ions (Ca, K, Mg, Na, HCO3, NO3, SO4, Cl) were determined. The water quality status for irrigation was determined based on the sodium adsorption ratio, salinity hazard, sodium percentage, magnesium hazard, residual sodium carbonate, Kelly's ratio and permeability index. Graphical presentation such as Wilcox diagram, Gibbs diagram, Schoeller diagram and Piper diagram were incorporated to display a wide range of water quality data. About 50% of the water samples collected from 30 sampling stations were beyond the good irrigation water class. The water quality at downstream was mostly unsatisfactory for irrigation purposes compared to water quality upstream, significantly proved at p<0.05. Cluster analysis revealed two different clusters of similarities between the points for both seasons, reflecting different chemical properties and irrigation water quality in the studied river

Groundwater resources assessment using numerical model : a case study in low-lying coastal area.

The impacts of climate change and human pressure in groundwater have been greatest threats facing small islands. This paper represents a case study of groundwater responses towards the climate change and human pressures in Manukan Island Malaysia. SEAWAT-2000 was used for the simulations of groundwater response in study area. Simulations of six scenarios representing climate change and human pressures showed changes in hydraulic heads and chloride concentrations. Reduction in pumping rate and an increase in recharge rate can alter the bad effects of overdrafts in Manukan Island. In general, reduction in pumping rate and an increase in recharge rate are capable to restore and protect the groundwater resources in Manukan Island. Thus, for groundwater management options in Manukan Island, scenario 2 is capable to lessen the seawater intrusion into the aquifer and sustain water resources on a long-term basis. The selection of scenario 6 is the preeminent option during wet season. The output of this study provides a foundation which can be used in other small islands of similar hydrogeological condition for the purpose of groundwater resources protection

A novel approach for the adsorption of cadmium ions in aqueous solution by dead calcareous skeletons

Heavy metal contamination in water causes problems to the environment and the deterioration of human health. Various types of water remediation methods have been conducted to counter this problem and to reduce the toxicity risk in water. As the conventional treatment process does not completely remove pollutants in the water, alternative purification methods have been studied to improve the treatment process. In this present study, batch experiments were conducted to evaluate the ability of dead calcareous skeleton in removing cadmium ions (Cd(II)) from aqueous solution. The factors affecting adsorption were evaluated in respect of adsorbent size, contact time, adsorbent dosage, pH, and initial concentration to determine the optimum conditions for Cd(II) removal. The optimum size of CS was 710 μm and the equilibrium was achieved at 600 min. The most favorable dosage concentration was 20 g/L. The optimum pH for the Cd(II) adsorption was 6.42, which is the initial pH of Cd(II) solution. The adsorption capacity of CS appeared to be higher when the initial concentration Cd(II) increased above 1 mg/L. The experimental data fitted better in the Freundlich isotherm than in the Langmuir isotherm but the bonding was rather weak. The results from this study demonstrate that dead calcareous skeletons have considerable potential in water treatment applications for the metal removal process. In addition, the cost of chemical usage can be reduced due to the natural characteristics of adsorbents, which are able to alter the pH of the solution so that it is favorable for optimum adsorption capacity

Study of hydrochemistry and seawater intrusion of Manukan Island, Sabah

A detailed groundwater, seawater and sediment study were undertaken to examine the evolution of groundwater in the shallow aquifer of Manukan island, Sabah, Malaysia. Its aquifer is often exposed to heavy pumping and that could lead to seawater intrusion. The continuous pumping of groundwater on this island has contributed to enrichment of some constituents found in seawater. As a consequence of indiscriminate exploitation, the groundwater quality of this island has deteriorated. Major ion chemistry analysis shows that the groundwater quality of the island experiences some changes attributed to seawater intrusion. Simple mixing between seawater-freshwater is complicated by the cation exchange process and highly associated with groundwater w itdrawal. This study indicates that the groundwater is classified as Na-Cl and Ca-Cl types. The groundwater has undergone a compositional change from Ca-rich to Na-rich which can be explained mostly by the cation exchange process. This study shows that the rise of Na and Cl composition in the groundwater is not only controlled by seawater intrusion, but also controlled by rapid cation exchange processes. Strong correlations exist among the major elements (Na, Mg, K, Cl and SO₄) and salinity with/or EC suggest that the impact of seawater intrusion to these major elements are more significant due to highly competitive relationship between ions. These relationships clearly identify the main elements contributing to the groundwater salinity and their tendency to depict a similar trend of salinization pattern. From the PHREEQC calculation, calcite, dolomite and aragonite solubility showed positive values of the saturation indices (SI), indicating supersaturation that lead to mineral precipitation condition of water by these minerals. Intensive exploitation of groundwater from Manukan Island's aquifer has disturbed the natural equilibrium between fresh and saline water, and has resulted in the increase of groundwater salinity and leap to the hydrochemical complexities of freshwater-seawater contact. It was observed that the mixing between fresh water seawater created diversity in the geochemical processes of Manukan Island's aquifer and altered the freshwater and seawater mixture away from the theoretical composition line. This explained the most visible processes taking place during the displacement. The results from reactive transport modelling confirmed that the migration of seawater into the fresher parts of the aquifer apparently leads to a calcification of the aquifer despite the seawater being supersaturated for carbonate minerals and shows that the composition of the near coast zone and further landward area may vary and have a significant effect on the processes during the intrusion

Status, source identification, and health risks of potentially toxic element concentrations in road dust in a medium-sized city in a developing country

This study aims to determine the status of potentially toxic element concentrations of road dust in a medium-sized city (Rawang, Malaysia). This study adopts source identification via enrichment factor, Pearson correlation analysis, and Fourier spectral analysis to identify sources of potentially toxic element concentrations in road dust in Rawang City, Malaysia. Health risk assessment was conducted to determine potential health risks (carcinogenic and non-carcinogenic risks) among adults and children via multiple pathways (i.e., ingestion, dermal contact, and inhalation). Mean of potentially toxic element concentrations were found in the order of Pb > Zn > Cr(IV) > Cu > Ni > Cd > As > Co. Source identification revealed that Cu, Cd, Pb, Zn, Ni, and Cr(IV) are associated with anthropogenic sources in industrial and highly populated areas in northern and southern Rawang, cement factories in southern Rawang, as well as the rapid development and population growth in northwestern Rawang, which have resulted in high traffic congestion. Cobalt, Fe, and As are related to geological background and lithologies in Rawang. Pathway orders for both carcinogenic and non-carcinogenic risks are ingestion, dermal contact, and inhalation, involving adults and children. Non-carcinogenic health risks in adults were attributed to Cr(IV), Pb, and Cd, whereas Cu, Cd, Cr(IV), Pb, and Zn were found to have non-carcinogenic health risks for children. Cd, Cr(IV), Pb, and As may induce carcinogenic risks in adults and children, and the total lifetime cancer risk values exceeded incremental lifetime

Evidence of seawater incursion due to over-exploitation of groundwater in a small tropical island: A statistical multivariate analysis.

In this paper, the differences of statistical outputs based on correlation analysis, cluster analysis and multiple linear stepwise regression analysis were useful to understand the seawater incursion due to over-exploitation of groundwater in Manukan Island. Therefore, the statistical multivariate analysis can be proposed and employed to hydrochemical data in order to see the changes due to anthropogenic activities in the future

A review on economically adsorbents on heavy metals removal in water and wastewater

Heavy metals contamination in water has been an issue to the environment and human health. The persisting contamination level has been observed and concerned by the public due to continuous deterioration of water quality. On the other hand, conventional treatment system could not completely remove the toxic metals in the water, thus alternative purification methods using inexpensive materials were endeavor to improve the current treatment process. Wide ranges of low cost adsorbents were used to remove heavy metal in aqueous solution and wastewater. The low cost adsorbents were usually collected from agricultural waste, seafood waste, food waste, industrial by-product and soil. These adsorbents are readily available in a copious amount. Besides, the pretreatment are not complicated to be conducted on the raw products, which is economically sound for an alternative treatment. The previous studies have provided much evidence of low cost adsorbents’ efficiency in removing metal ions from aqueous solution or wastewater. In this review, several low cost adsorbents in the recent literature have been studied. The maximum adsorption capacity, affecting factors such as pH, contact times, temperature, initial concentration and modified materials were revised and summarized in this review for further reference. Comparisons of the adsorbent between the modified and natural products were also demonstrated to provide a clear understanding on the kinetic uptake of the selected adsorbents. Some of the natural adsorbents appeared as good heavy metal removal, while some were not and require further modifications and improvements to enhance the adsorption capacity. SWOT analysis (strength, weakness, opportunities, threat) was also performed on the low cost adsorbents to identify the advantages of using low cost adsorbents and solve the weaknesses encountered by the utilization of low cost materials. This tool helps to determine the potential quality of low cost materials in the application for water and wastewater treatment

Experimental determination of Cd2+ adsorption mechanism on low-cost biological waste.

Carbonate shells have an astonishing ability in the removal of Cd2+ in a short time period with emphasis on being a low cost adsorbent. In the present study, the sorption capacity of carbonate shells was studied for Cd2+ in batch experiments. The influence of different carbonate shell sizes and physico-chemical factors were evaluated and the results were analyzed for its correlation matrices by using Predictive Analytics Software (PASW). The mineralogy state of aqueous solution regarding the saturation index was simulated using PHREEQC to identify the Cd2+ uptake mechanism. The Cd uptake rates were calculated as well as Ca2+, HCO 3 − concentration, pH, ambient humidity and temperature were measured. Cd2+ removal of 91.52% was achieved after 5 h adsorption. The adsorption efficiencies were significantly influenced by pH as they increased with the increase of pH from acidic solution (5.50±0.02) to slightly alkaline (7.60±0.05). In addition, the mineralogy state of aqueous solution calculated from PHREEQC confirmed that the increment of Ca2+ and HCO 3 − concentrations in solution was attributed to the dissolution of carbonate shells. Moreover, the ion exchange adsorption mechanism of Cd2+ toward Ca2+ was identified as the process involved in Cd2+ uptake