Ley Juen Looi

Baseline metals pollution profile of tropical estuaries and coastal waters of the Straits of Malacca

The status report on metal pollution in tropical estuaries and coastal waters is important to understand potential environmental health hazards. Detailed baseline measurements were made on physicochemical parameters (pH, temperature, redox potential, electrical conductivity, salinity, dissolved oxygen, total dissolved solid), major ions (Na, Ca, Mg, K, HCO3, Cl, SO4 and NO3) and metals concentrations ((27)Al, (75)As, (138)Ba, (9)Be, (111)Cd, (59)Co, (63)Cu, (52)Cr, (57)Fe, (55)Mn, (60)Ni, (208)Pb, (80)Se, (66)Zn) at estuaries and coastal waters along the Straits of Malacca. Principal component analysis (PCA) was employed to reveal potential pollution sources. Seven principal components were extracted with relation to pollution contribution from minerals-related parameters, natural and anthropogenic sources. The output from this study will generate a profound understanding on the metal pollution status and pollution risk of the estuaries and coastal system.

The levels of mercury, methylmercury and selenium and the selenium health benefit value in grey-eel catfish (Plotosus canius) and giant mudskipper (Periophthalmodon schlosseri) from the Strait of Malacca.

The present study examined the concentrations of mercury (Hg), methylmercury (MeHg), and selenium (Se) in the multiple tissues of the Plotosus canius and Periophthalmodon schlosseri collected from the Strait of Malacca. The mean value in mg kg(-1) of Hg (P. canius: 0.34 ± 0.19; P. schlosseri: 0.32 ± 0.18) and MeHg in muscle (P. canius: 0.14 ± 0.11; P. schlosseri: 0.17 ± 0.11) were below the Codex general standard for contaminants and toxins in food and feed (CODEX STAN 193-1995), the Malaysian Food Regulation 1985 and the Japan Food Sanitation Law. For P. canius, the liver contained the highest concentrations of Hg (0.48 ± 0.07 mg kg(-1)) and MeHg (0.21 ± 0.00 mg kg(-1)), whereas for P. schlosseri, the gill contained the highest concentrations of Hg (0.36 ± 0.06 mg kg(-1)) and MeHg (0.21 ± 0.05 mg kg(-1)). The highest concentration of (80)Se (mg kg(-1)) was observed in the liver of P. canius (20.34 ± 5.68) and in the gastrointestinal tract (3.18 ± 0.42) of P. schlosseri. The selenium:mercury (Se:Hg) molar ratios were above 1 and the positive selenium health benefit value (HBVSe) suggesting the possible protective effects of Se against Hg toxicity. The estimate weekly intakes (EWIs) in μg kg(-1) body weight (bw) week(-1) of Hg (P. canius: 0.27; P. schlosseri: 0.15) and MeHg (P. canius: 0.11; P. schlosseri: 0.08) were found to be lower than the provisional tolerable weekly intake established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). Based on the calculated EWIs, P. canius, and P. schlosseri were found to be unlikely to cause mercury toxicity in human consumption.

Natural and Anthropogenic Determinants of Freshwater Ecosystem Deterioration: An Environmental Forensic Study of the Langat River Basin, Malaysia

Freshwater ecosystems face numerous threats that challenge the local authorities’ ability on tackling down the water security (quantity and quality) issues and their management. The quality of surface water is an essential component of the natural environment and is considered as the main factor for controlling ecosystem health and potential hazard to the surrounding environment. The Langat River Basin in Selangor, Malaysia is exposed to natural and anthropogenic activities. A forensic investigation via the use of geostatistical and geochemical approaches and different standard criteria revealed two sources controlling the evolution of Langat River Basin water chemistry: (i) anthropogenic (agricultural and industrial activities) and (ii) natural processes (seawater intrusion and geological weathering). In addition, the suitability of river water for various purposes was determined based on the application of selected indicators and indices. The findings serve as an essential platform for the protection of water resources.

Estuaries Ecosystems Health Status – Profiling the Advancements in Metal Analysis

Estuaries are highly productive areas, which play an important role in both ecological and socioeconomic aspects. It is an excellence sanctuary for a wide variety of aquatic organisms and wildlife that breed and inhabit in these areas. Despite the importance of estuaries, they are being threatened and damaged at an alarming rate. Metal pollution is among the most serious environmental crises in estuaries ecosystems. The anthropogenic activities had resulted in the increase of metal elements released or leached into the environment. As such, deterioration of estuaries ecosystem health status by these substances promoted an urgency to monitor the concentration of metals in the environment. Although metals pollution studies have been carried out extensively all over the world but unfortunately there are still no measurements that can be fully rely to predict the effect of metal pollution on estuarine ecosystems. Therefore, current chapter is indispensable to demonstrate the advances of analytical methods and detection techniques available for metals analyses. In addition, environmental forensic approaches and application of various metal pollution indicators, indices, modeling and statistical analysis in assessing estuarine ecosystem health status was also has been highlighted in this chapter. This chapter also pointed out the gap of knowledge which should be addressed for future risk assessment of metals pollution in estuaries ecosystem. Current chapter could be served as a reference for future metals comparative studies and monitoring works to be carried out effectively.

Assessment of water quality using environmetric techniques at Johor River

In this study, the spatial water parameters of Johor River from 2003–2007 were analyzed by using environmetric techniques namely the hierarchical agglomerative cluster analysis (HACA), discriminant analysis (DA) and principle component analysis (PCA). These methods were used to determine the spatial variations and sources of pollutants in Johor River. There were 23 water parameters selected namely DO, BOD, COD, SS, pH, NH3-NL, temperature, conductivity, salinity, turbidity, DS, TS, NO3, Cl, PO4, Zn, Ca, Fe, K, Mg, Na, E-coli and coliform. The HACA has grouped the water monitoring stations along the Johor River into three clusters; (1) the stations with low pollution sources (LPS), (2) moderate pollution sources (MPS) and (3) high pollution sources (HPS). Stations are classified into three clusters based on the similarity of each variable poses towards each other. Ten water parameters were being discriminated by conducting forward stepwise DA out of the 23 water quality variables. PCA were then conducted to identify the pollutant sources from the landuse of the area. Eight principle components (PCs) were obtained with 79 % variation of LPS region. Five PCs were obtained from MPS with the total variation of 84 % of the MPS region. The HPS has the most number of PCs which are nine PCs with a total variation of 83 % of its region. For the MPS and HPS, the pollutants were introduced by human activities such as discharge of chemicals, industrial wastewater, agricultural activities and urban development activities.

Factor Controlling the Total Exchangeable Cation of Estuaries and Coastal Sediment

A preliminary study on exchangeable cation of sediments was conducted at 56 sampling stations along the Straits of Malacca in order to examine the most significant factor that control the total exchangeable cations in estuaries and coastal sediments. Physico-chemical characteristics (pH, salinity, and electrical conductivity), and organic matter content were determined in the laboratory. Total exchangeable cations (Na+, K+, Ca2+, and Mg2+) of sediment samples were analysed using flame atomic absorption spectrophotometer. The pH (2.85–7.97), electrical conductivity (8.92–46.37 μS/cm), salinity (4.97–30.13 ppt), organic matter (2.34–14.76 %), exchangeable sodium (23.98–123.65 meq/100 g), exchangeable potassium (0.05–3.08 meq/100 g), exchangeable calcium (3.42–18.98 meq/100 g), and exchangeable magnesium (5.96–24.12 meq/100 g) of estuaries and coastal sediments showed variations. Principal component analysis employed in this study clearly shows that exchangeable Na+ was controlled by salinity which is mainly contributed from halite minerals (NaCl) and electrical conductivity. Thus, halite does play an important role in influencing the total exchangeable cations in estuaries and coastal waters.

Tape seagrass (Enhalus acoroides) as a bioindicator of trace metal contamination in Merambong shoal, Johor Strait, Malaysia

Revealing the potential of seagrass as a bioindicator for metal pollution is important for assessing marine ecosystem health. Trace metal (111Cd, 63Cu, 60Ni, 208Pb, 66Zn) concentrations in the various parts (root, rhizome, and blade) of tape seagrass (Enhalus acoroides) collected from Merambong shoal of Sungai Pulai estuary, Johor Strait, Malaysia were acid-extracted using a microwave digester and analysed via inductively coupled plasma-mass spectrometry (ICP-MS). The ranges of trace metal concentrations (in μgg-1 dry weight) were as follows: Cd (0.05-0.81), Cu (1.62-27.85), Ni (1.89-9.35), Pb (0.69-4.16), and Zn (3.44-35.98). The translocation factor revealed that E. acoroides is a hyperaccumulator plant, as its blades can accumulate high concentrations of Cd, Cu, Ni, and Zn, but not Pb. The plant limits Pb mobility to minimize Pbs toxic impact. Thus, E. acoroides is a potential bioindicator of metal pollution by Cd, Cu, Ni, and Zn in estuarine environments.