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A total of 97 surficial sediment samples were collected from the Kelantan River, Pahang River and offshore water of Peninsular Malaysia located in the east coast mainly in to investigate the sources and sinks of 210Pb in the southern South China Sea region. At the locations studied, the concentration activity of 210Pb was recorded from the Kelantan River (n = 28), Pahang River (n = 44) and offshore waters (n = 25), ranging from 2.7 ± 0.46 Bq/kg to 52.07 ± 5.23 Bq/kg, 8.65 ± 3.56 Bq/kg to 83.04 ± 6.71 Bq/kg, and 6.72 ± 2.92 Bq/kg to 42.2 ± 3.94 Bq/kg, respectively. Both riverine systems received huge amounts of 210Pb concentrations via mobilised particulate matter, where erosional igneous rocks and weathered sedimentary layers were prominent in elevating the amount of 210Pb from the source towards the sinks. In the offshore margins, the concentrations differed according to the source. As both rivers move towards the sinks in the coastal territories, boundary scavenging becomes prominent. In the offshore territories, a deficiency of 210Pb leads to excess 226Ra in the water column. Scavenged nuclide imported from several sources may increase the total concentrations lingering in the offshore waters of Peninsular Malaysia. Particulate matter mobilised from several sources via upwelling or downwelling in the bottom current through lateral transport further enhances the removal of particle-reactive nuclides from the water column. At the same time, atmospheric deposition via precipitation and transboundary mobilisation of aerosol by mineral dust may increase the total flux on the offshore waters of Peninsular Malaysia.

To understand the modern sedimentation and land-sea interaction processes in the Sunda Shelf, we evaluated the rare earth element (REE) compositions, the total organic carbon (TOC) contents, grain sizes, and detrital minerals of 39 surface sediments, collected from the western Sunda Shelf. All of the sampled sediments are characterised by a higher content of light REEs (LREEs) relative to the content of heavy REEs (HREEs) with negative Eu anomalies. The total content of REE (ΣREE) in the sediments ranges from 7 μg/g to 193 μg/g, with an average of 119 μg/g. Due to the uneven spatial distribution of REEs in the study area, a Q-cluster analysis is applied to the mean grain size (Mz), ∑REE, δEu, δCe, (La/Yb)N, and (Gd/Yb)N data. On this basis, the study area can be classified into three geochemical provinces. The north to central zone in the study area is designated as province I, which has the highest REE content among the three provinces. This is a result of the finer grain size, dominance of siderite, and higher TOC contents of the sediments in province I. The REE content of province II in the southwest coastal zone is lower than that of province I due primarily to a coarser grain size and high quartz, biodetritus, and plagioclase contents. Covering the central coastal zone, province III has the lowest REE content among the three provinces because of the extremely coarse grain size and very high quartz and biodetritus contents. The upper continental crust (UCC)-normalised REE patterns differ markedly among the three provinces, thereby indicating different provenances and transport mechanisms. Based on the provenance discrimination plot and the UCC-normalised REE patterns of these three provinces and adjacent rivers, we infer that province I is largely fed by the Mekong and Kelantan rivers. The fine-grained sediments from these rivers are transported to north and central zone by the northeast monsoon current. The Pahang River is identified as the main sediment source of province II. The coarse-grained sediments from this river mostly accumulate near the estuary via hydrodynamic sorting, while finer-grained sediments are transported to the south by the southward coastal currents. The sediments in province III are inferred as being primarily the result of coastal erosion due to the strong wave energy in this area, as well as offshore and longshore sediment transport acting, in parallel to the coast line. Our study can serve as a reference for studying the diffusion and transport processes of mountainous river sediment and the evolution of the paleoclimate and paleoenvironment in tropical low-latitude regions.

Sediment core collected from Tanjung Pelepas harbour was analyzed to determine the concentrations of trace metals e.g., Al, Fe, Ti, Pb, Zn, Cu and natural radionuclide 210Pb. The aim of this study was to predict the origin of trace metals and date the deposition of sediment that occurred at Tanjung Pelepas harbour using the vertical profile of 210Pb. The estimated sedimentation rate derived from 210Pb profile was 0.57cm/year. The entire datasets of trace metals were analyzed statistically using the Pearson correlation coefficient and principal component analysis (PCA) to predict their origins. The results showed that Al, Fe and Ti originated from natural sources while Zn and Cu came mainly from anthropogenic sources. Pb was dominated with both anthropogenic and natural sources. The enrichment factors (EF) were also calculated to estimate the level of contamination. The EF indicated that Tanjung Pelepas harbour is considered to have minor enrichment (EF

Grain size is an important controlling factor of the chemical composition of sediments. To understand the role of grain size in the content of rare earth elements (REE) in tropical mountainous river sediments and to establish suitable provenance proxies, sediments collected from Pahang River and Kelantan River, Peninsular Malaysia, were determined for REE contents in six size fractions (

A study was done to determine the concentrations of surfactants on the sea-surface microlayer and in atmospheric aerosols in several coastal areas around the Malaysian peninsula. The concentrations of surfactants from the sea-surface microlayer (collected using rotation drum) and from aerosols (collected using HVS) were analyzed as methylene blue active substances and disulphine blue active substances through the colorimetric method using a UV-vis spectrophotometer. The results of this study showed that the average concentrations of surfactants in the sea-surface microlayer ranged between undetected and 0.36+/-0.34 micromol L(-1) for MBAS and between 0.11+/-0.02 and 0.21+/-0.13 micromol L(-1) for DBAS. The contribution of surfactants from the sea-surface microlayer to the composition of surfactants in atmospheric aerosols appears to be very minimal and more dominant in fine mode aerosols.

The East Coast of Peninsular Malaysia faces the South China Sea and is vulnerable to oil pollution because of intense petroleum production activities in the area. The South China Sea is also a favored route for supertankers carrying crude oil to the Far East. Consequently, oil spills can occur, causing pollution and contamination in the surrounding areas. Residual oil spills stranded on coastal beaches usually end up as tar-balls. Elucidating the sources of tar-balls using a molecular marker approach is essential in assessing environmental impacts and perhaps settling legal liabilities for affected parties. This study utilizes a multimodal molecular marker approach through the use of diagnostic ratios of alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) to determine the source, distribution and weathering of tar-balls. Hopane ratios (e.g., C29/C30, and summation C31-C35/C30 ratios) were used to identify the sources of tar-balls. The weathering effects were distinguished by using alkanes, namely the unresolved complex mixture (UCM) and low molecular weight/high molecular weight (L/H) ratios. Similarly, PAHs were also used for the determination of weathering processes undergone by the tar-balls. This multimodal molecular marker gave a very strong indication of the sources of tar-balls in this study. For example, 16 out of 17 samples originated from South East Asian Crude Oil (SEACO) with one sample from Merang, Terengganu originating from North Sea Oil (Troll). The TRME-2 sample may have come from a supertanker's ballast water discharge. The second possibility is that the tar-ball may have been transported via oceanographic currents. All 'weathered' sample characterizations were based on the presence of UCM and other ratios. The multimodal molecular marker approach applied in this study has enabled us to partially understand the transport behavior of tar-balls in the marine environment and has revealed insights into the weathering process of tar-balls.