Environmental occurrence and assessment of organic pollutants in surface sediments of South Peninsular Malaysia.

Organic pollution continues to be an important worldwide obstacle for tackling health and environmental concerns that require ongoing and prompt response. To identify the LAB content levels as molecular indicators for sewage pollution, surface sediments had obtained from the South region of Malaysia. The origins of the LABs were identified using gas chromatography-mass spectrometry (GC-MS). ANOVA and a Pearson correlation coefficient at p < 0.05 were used in the statistical analyses of the differences between the research locations. Internal to external (I/E) ratio, homologs C13/C12, and long to short (L/S) chains are used to identify the effectiveness of wastewater treatments. According to statistical analysis, the range of LAB level at the stations was 67.4 to 188.7 ng g-1dw. A significant difference was observed between LAB homologs (p < 0.05), with a higher level of C13 in most of the stations. The computed LAB ratio (I/E), which varied from 1.6 to 2.7, revealed the released wastewater from primary and secondary sources. LAB degradation varied between 33 and 49% in the areas that were evaluated. The treatment system of wastewater requires to be further improved, and using LAB markers to track anthropogenic contamination is imperative.

An evaluation of spatial and seasonal distributions of dissolved trace metals in the water of the natural wetlands.

The spatial and temporal distributions of trace metals in dissolved forms mainly result from anthropogenic and lithogenic contributions. Surface water samples (∼0.5 m) were collected monthly at respective stations from Setiu Wetland. In this study, the behaviour of trace metals in the dissolved phases along the water column from sampling sites in the Setiu Wetland, Malaysia was investigated. In addition, dissolved organic carbon (DOC) and physical parameters such as salinity, temperature, pH and dissolved oxygen (DO) of the surface water were measured in order to evaluate the relationship between trace metals fractionation with different water quality parameters. Size fractionation study of dissolved trace metals using ultrafiltration technique were also carried out and analysed using inductively coupled plasma mass spectrometry (ICP-MS). Correlation of trace metals with other measured parameters was made to furthermore understand the dynamics of trace metals and its fractionated components in this area. The concentration of dissolved trace metals was in the range of 0.001-0.16 µg/L for Cd, 0.12-2.81 µg/L for Cu, 0.01-1.84 µg/L for Pb, 3-17 µg/L for Fe and 1-34 µg/L for Zn, suggesting the input of anthropogenic sources for trace metals such as municipal, industrial, agricultural and domestic discharge. The periodic monitoring and evaluation of trace metals in wetlands and protected tropical areas is highly recommended.

Lateral distribution, environmental occurrence, and assessment of organic pollutants in surface sediments of the East Malaysia.

One of the molecular chemical markers used to identify anthropogenic inputs is linear alkylbenzenes (LABs) that cause serious impacts in the bays and coastal ecosystems. The surface sediments samples collected from the East Malaysia, including Brunei bay to estimate the LABs concentration and distribution as molecular markers of anthropogenic indicators. Gas chromatography-mass spectrometry (GC-MS) was used after purification, fractionation the hydrocarbons in the sediment samples to identify the sources of LABs. The analysis of variance (ANOVA) and Pearson correlation coefficient were applied to analyze the difference between sampling stations' significance at p < 0.05. Long to short chains L/S, homologs C13/C12, and internal to external (I/E) congeners have used to assess the LABs degradation rates as well as the effectiveness of sewage treatment. Results of this study showed that the LABs concentration ranged between 7.1 to 41.3 ng g-1 dw, in the investigated stations. The majority of sample sites exhibited a considerable input of C13-LABs homologs, and LABs homologs differed significantly. The estimated LABs ratios (I/E), which ranged between 0.6 and 2.2, demonstrated the effluents with primary and less secondary sources are released into the bay waters. The degradation of LABs were up to 42% in the interrogated locations. The conclusion is that the wastewater treatment system needs to be improved, and that LABs molecular markers are highly effective in tracing anthropogenic sewage contamination.

Source apportionment and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the coastal ecosystem of the Brunei Bay, Brunei.

Pollution characteristics and associated ecological risks of PAHs in sediments from Brunei Bay, Brunei were investigated. The concentrations of ∑16 PAHs ranged from 826.7 to 2955.3 µg kg-1, indicating moderate to high level of pollution. Source apportionment of PAHs by molecular isomeric ratios and positive matrix factorization model indicated impact of potential anthropogenic PAH sources including combustion of biomass and fossil fuels. The data indicated relatively no significant ecotoxicological risk for most of PAH compounds. To estimate the individual c-PAH toxicity, the toxic equivalent quantity (c-TEQ) was calculated. Results of the TEQ analysis showed that BaP followed by DBA and BaA are the most carcinogenic of PAHs examined in the study area. The evaluation of human health risk of PAHs revealed that the cancer risk of PAHs for adults and children was higher than the USEPA threshold (<1E-06) and lower than 1E-3, implying low to moderate risk.

Determination of linear alkylbenzenes (LABs) in mangrove ecosystems using the oyster Crassostrea belcheri as a biosensor.

The current study aimed to develop a suitable molecular marker [Linear alkylbenzenes (LABs)] approach for pollution determination in mangrove oysters of peninsular Malaysia. C. belcheri species were collected from rivers of Merbok, Perai, Klang, Muar and PulauMerambong (An Island). The LABs were extracted from C. belcheri and determined using GC-MS. The LABs indices which included I/E, L/S and C13/C12 were applied to describe the sources and biodegradation of LABs. The results revealed that the maximum concentrations were detected in oysters from Klang (27.91 ng g-1dw), while the lowest concentrations were detected in oysters from Merbok (8.12 ng g-1dw). Moreover, I/E ratios varied between 2.83 and 6.40, indicating the secondary treatment effluents being discharged to coastal zones. The results of this study suggested that the oysters absorbed LABs mainly in dissolved phase. Therefore, mangrove oysters are a good biosensor for LABs contamination in the aquatic environment.

Linear alkylbenzenes in surface sediments of an estuarine and marine environment in peninsular Malaysia.

Linear alkylbenzenes were determined in the surface sediments of Muar River and Pulau Merambong, Peninsular Malaysia. The concentrations ranged from 87.4 ng g-1 to 188.1 ng g-1 and from 67.4 ng g-1 to 98.2 ng g-1 of dry weight, respectively. The composition profiles of LABs were characterized, and sewage treatment levels were identified. The ratios of internal to external isomers (I/E ratios) of the linear alkylbenzenes in Muar River sediments ranged from 1.7 to 2.2, whereas those of Pulau Merambong sediments ranged from 1.6 to 1.7. The calculated LAB ratios indicated that the study areas received primary and secondary sewage effluents. The degradation of linear alkylbenzenes in Muar River ranged from 33% to 43%, and that in Pulau Merambong ranged from 33% to 34%. The higher degradation indices in Muar River are a sign of improvement in wastewater treatment.

Seasonal variability of anthropogenic indices of PAHs in sediment from the Kuala Selangor River, west coast Peninsular Malaysia.

Rapid increase in industrialization and urbanization in the west coast of Peninsular Malaysia has led to the intense release of petroleum and products of petroleum into the environment. Surface sediment samples were collected from the Selangor River in the west coast of Peninsular Malaysia during four climatic seasons and analyzed for PAHs and biomarkers (hopanes). Sediments were soxhlet extracted and further purified and fractionated through first and second step column chromatography. A gas chromatography-mass spectrometry (GC-MS) was used for analysis of PAHs and hopanes fractions. The average concentrations of total PAHs ranged from 219.7 to 672.3 ng g-1 dw. The highest concentrations of PAHs were detected at 964.7 ng g-1 dw in station S5 in the mouth of the Selangor River during the wet inter-monsoonal season. Both pyrogenic and petrogenic PAHs were detected in the sediments with a predominance of the former. The composition of hopanes was homogeneous showing that petroleum hydrocarbons share an identical source in the study area. Diagnostic ratios of hopanes indicated that some of the sediment samples carry the crankcase oil signature.

Anthropogenic waste indicators (AWIs), particularly PAHs and LABs, in Malaysian sediments: Application of aquatic environment for identifying anthropogenic pollution.

Polycyclic aromatic hydrocarbons (PAHs) and linear alkylbenzenes (LABs) were used as anthropogenic markers of organic chemical pollution of sediments in the Selangor River, Peninsular Malaysia. This study was conducted on sediment samples from the beginning of the estuary to the upstream river during dry and rainy seasons. The concentrations of Æ©PAHs and Æ©LABs ranged from 203 to 964 and from 23 to 113 ng g(-1) dry weight (dw), respectively. In particular, the Selangor River was found to have higher sedimentary levels of PAHs and LABs during the wet season than in the dry season, which was primarily associated with the intensity of domestic wastewater discharge and high amounts of urban runoff washing the pollutants from the surrounding area. The concentrations of the toxic contaminants were determined according to the Sediment Quality Guidelines (SQGs). The PAH levels in the Selangor River did not exceed the SQGs, for example, the effects range low (ERL) value, indicating that they cannot exert adverse biological effects.

Forensic investigation of aliphatic hydrocarbons in the sediments from selected mangrove ecosystems in the west coast of Peninsular Malaysia.

Peninsular Malaysia has gone through fast development during recent decades resulting in the release of large amounts of petroleum and its products into the environment. Aliphatic hydrocarbons are one of the major components of petroleum. Surface sediment samples were collected from five rivers along the west coast of Peninsular Malaysia and analyzed for aliphatic hydrocarbons. The total concentrations of C10 to C36 n-alkanes ranged from 27,945 to 254,463ng·g(-1)dry weight (dw). Evaluation of various n-alkane indices such as carbon preference index (CPI; 0.35 to 3.10) and average chain length (ACL; 26.74 to 29.23) of C25 to C33 n-alkanes indicated a predominance of petrogenic source n-alkanes in the lower parts of the Rivers, while biogenic origin n-alkanes from vascular plants are more predominant in the upper parts, especially in less polluted areas. Petrogenic sources of n-alkanes are predominantly heavy and degraded oil versus fresh oil inputs.