This study investigates the presence and distribution of organochlorine pesticides in streams and the lake in the Sembrong Lake Basin in Malaysia. The catchment of Sembrong Lake has been converted to agricultural areas over the past 30 years, with oil palm plantations and modern agricultural farming being the main land use. Surface water samples were collected from eight sites comprising the stream and lake and analysed for 19 organochlorine pesticides (OCPs). In situ measurement of temperature, dissolved oxygen, pH and conductivity were also undertaken at each site. Aldrin, endrin, δ-BHC, 4,4-DDT, methoxychlor and endosulfan were the main OCPs detected in the lake basin. The total OCP concentration ranged between 5.42 and 349.2 ng/L. The most frequently detected OCPs were δ-BHC, heptachlor and aldrin. The maximum values detected were 23.0, 43.2 and 50.4 ng/L respectively. The highest concentration of OCPs was attributed to 4,4-DDT, but such high residue was rare and only detected once. Other OCP residues were low. Significant differences in the mean values were observed between lake and stream for dichlorodiphenyldichloroethylene (DDE) and α-endosulfan concentration (p
Seasonal variations in total mercury concentrations [Hg] and trophic transfer through the food web were assessed using stable isotopic tracers for the Setiu Wetlands, Terengganu. The [Hg] measured in surface sediments and biota varied inversely between wet and dry seasons. Increased rainfall and water disturbance during the wet season are suggested as the main factors releasing Hg from surface sediments and enhancing the bioavailability of Hg to biota. The elevated Hg levels associated with the leaf stage suggested that litterfall and atmospheric deposition may be the main Hg inputs into mangrove food webs. The positive relationships between log [Hg] and δ15N provided evidence for Hg biomagnification, however low trophic magnification slopes in both seasons indicated that the ecological risk of Hg in the wetland would be negligible. The [Hg] in fish and commercial crabs were below the permitted limits for human consumption.
The distribution of total petrogenic hydrocarbon was investigated in the subsurface water of Setiu Wetland from July to October 2008. The concentration was quantified by UV-fluorescence spectroscopy and ranged from 4 to 121 μg/L (mean 60 ± 41 μg/L). Higher total petrogenic hydrocarbon concentrations were found in area with high boating activities suggesting that the contribution is likely related to fossil fuel combustion. The present study also revealed that the total petrogenic hydrocarbon values are still lower that those reported in Malaysian coastal waters.
This paper presents a preliminary result carried out in the Besut River basin, Terengganu, Malaysia to determine the selected trace metal concentrations. Concentrations of dissolved Pb, Cu, and Fe during the present study were in the range of 3.3-8.3 microg/L Pb, 0.1-0.3 microg/L Cu, and 1.1-12.3 microg/L Fe. For the particulate fraction concentrations of Pb, Cu, and Fe ranged from 1.0 to 3.6 microg/L, 0.3 to 2.8 microg/L, and 114 to 1,537 microg/L, respectively. The concentrations of metals in this study area, in general, were lower than those reported for other study areas. Higher metal concentrations measured in the wet monsoon season suggest that the input was mainly due to terrestrial runoff.
A study to determine the impact of leachate from operating and closed landfills into the surface water and groundwater systems in the state of Selangor was conducted in the year 2009. Groundwater was a major source of water for various uses in Selangor, Malaysia and was especially important for industrial purposes. The presence of high numbers of landfill sites was seen to have increased the risk of groundwater contamination. There were 20 landfill sites in the state of Selangor and seven of them were still operating and 13 closed. The landfills are classified into four categories, which were: (a) landfills operating at critical stages without controls to prevent pollution into the environment; (b) open dumpsites that have the capacity to continue to accept waste but needed to be upgraded to manage leachate and gas; (c) landfills that were closed but no safety closure plan was carried out; and (d) engineered landfills with up to date technologies. As most of the landfills were built prior to 1989, they were not subjected to the Environmental Impact Assessment requirements, hence, they were being poorly managed and were badly sited. The non-engineered sites had no proper pollution controls such as cover materials, liner materials, groundwater monitoring wells, leachate collection ponds and treatment, and methane gas collection pipes. This study revealed that the surface water and groundwater at and nearby the landfill sites were contaminated at various levels due to the landfill sites and operation. A comparison between the current quality of surface water and groundwater with their respective standards and background levels was carried out to survey the trend of the contamination. However, the limited financial resources hindered a very thorough investigation and restricted the number of samples collected and parameters analysed.
This study determines the bulk surface water (BSW) dissolved inorganic nutrients of nitrogen (DINi) and phosphate (DIP) during the upwelling season off the east coast of Peninsular Malaysia, South China Sea. BSW samples were analysed for DINi and DIP by using a standard automated colorimetric method. BSW DINi and DIP concentrations varied between 0.11 and 2.55 μM (mean 1.12 ± 0.63 μM), and below detection limit, and 0.29 μM (mean 0.11 ± 0.08 μM), respectively. The spatial distribution of higher concentrations between DINi and DIP was distinct. However, the highest concentrations of DINi and DIP were mostly recorded in the month of peak upwelling (July and August), where colder BSW temperatures were also encountered during field sampling. This study provides new evidence on the presence of BSW nutrients of DINi and DIP during upwelling season peak in July and August before their decline in September.
Terrestrial anionic surfactants (AS) enter the marine environment through coastal region. Despite that, in general limited knowledge is available on the coastal AS transfer pathway. This paper aims to assess the distributions and exchange of AS in the Peninsular Malaysia coastal environments, adjacent to the southern waters of South China Sea and Strait of Malacca. An assessment case study was conducted by a review on the available data from the workgroup that span between the year 2008 and 2019. The findings showed that AS dominated in the sea surface microlayer (SML, 57%) compared to subsurface water (SSW, 43 %). AS were also found to have dominated in fine mode (FM, 71 %) compared to coarse mode (CM, 29 %) atmospheric aerosols. SML AS correspond to the SSW AS (p < 0.01); however, highest enrichment factor (EF) of the SML AS was not consistent with highest SSW AS. Direct AS exchange between SML and FM and CM was not observed. Furthermore, the paper concludes AS mainly located in the SML and FM and could potentially be the main transfer pathway in the coastal environment.
This study was conducted to determine the composition and source apportionment of surfactant in atmospheric aerosols around urban and semi-urban areas in Malaysia based on ionic compositions. Colorimetric analysis was undertaken to determine the concentrations of anionic surfactants as Methylene Blue Active Substances (MBAS) and cationic surfactants as Disulphine Blue Active Substances (DBAS) using a UV spectrophotometer. Ionic compositions were determined using ion chromatography for cations (Na(+), NH4(+), K(+), Mg(2+), Ca(2+)) and anions (F(-), Cl(-), NO3(-), SO4(2-)). Principle component analysis (PCA) combined with multiple linear regression (MLR) were used to identify the source apportionment of MBAS and DBAS. Results indicated that the concentrations of surfactants at both sampling sites were dominated by MBAS rather than DBAS especially in fine mode aerosols during the southwest monsoon. Three main sources of surfactants were identified from PCA-MLR analysis for MBAS in fine mode samples particularly in Kuala Lumpur, dominated by motor vehicles, followed by soil/road dust and sea spray. Besides, for MBAS in coarse mode, biomass burning/sea spray were the dominant source followed by motor vehicles/road dust and building material.
Heavy metal pollution in an aquatic environment has become of the main concern to the world due to their non-biodegradable properties, toxicity, persistence, and their ability to adsorb into food chains. With rapid industrialization and development nowadays, heavy metals are introduced continuously into the estuaries and coastal region through rivers, runoff, and land-based point sources. These heavy metals may degrade the aquatic environment and harm the living organisms and toward human indirection through secondary contact. The dataset provided is to give an overview of the spatial and temporal distribution of the heavy metals concentration in Merang River surficial sediment collected from September 2017 to July 2018, subsequently every two months dataset. Sediment samples were collected in 44 stations along the river and 20 stations in the coastal area, which total up to 64 stations. Teflon Bomb closed digestion method with mixed acid was used to digest the sediments. The concentration of heavy metals in the sediment were analysed by using Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The spatial distribution of heavy metals shows the effect of monsoon and wet and dry seasons in the sampling area. Thus, this dataset reveals six months of information on natural and anthropogenic sources intrusion at the Merang River and may also help in monitoring the pollution in the area.