Elemental Assessments Of South China Sea Marine Sediments Along The East Coast Of Peninsular Malaysia

Malaysia is located in the west of the South China Sea and is divided into two major land masses, i.e., Peninsular Malaysia and East Malaysia on the Island of Borneo, with a total coast line of 4675 km (Peninsular Malaysia 2068 km; East Malaysia 2607 km). As most seas, the majority of pollution occurs in the South China Sea arise from the land namely waste that comes from large cities (sewage, industrial waste and hydrocarbons) and agricultural runoff (nutrients, pesticides and fertilizers). The aim of this research is to access information on horizontal elemental distribution of coastal surface sediments and on vertical elemental distribution of offshore core sediments and to determine the status of pollution in the surface and core marine sediments. The results of this research together with experimental data from other researches on marine sediments on the east coast of Peninsular Malaysia may be used to establish a baseline data for this region. All together 43 elements were identified and then classified according to heavy metals (As, Cd, Cu, Cr, Ni, Pb and Zn), trace elements (B, Ba, Be, Bi, Br Co, Cs, Ga, Ge, Hf, Li, Mo, Nb, Sc, Rb, Sb, Sn, Sr, Ta, V, W, Y and Zr), rear earth elements (Ce, Dy, Eu, La, Lu, Nd, Sb, Sm and Yb), major elements (Al, Ca, K, Fe, Mg, Mn Na, P, S and Ti), and actinides elements (Th and U) depending on their physical and chemical characteristics. The elemental concentrations of the surface sediments from 10 stations and the core sediments from 5 stations have been determined using the Instrumental Nuetron Activation Analysis (INAA) at Nuclear Agency Malaysia and the Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) at Geological Survey of Iran (GSI) laboratories. To know the status of contamination in heavy metals and trace elements, the enrichment factor, geoaccumulation index (Igeo) and modified degree of contamination (mCd) methods were used to interpret the results. Where appropriate the linear regression analysis, pearson‘s correlation factors, first and second of the principal component analysis and the cluster analysis were performed to determine the relationships between obtained results. For the surface elemental distributions, heavy metal Pb was found to be originated from anthropogenic sources at the stations at the larger river mouths of Kelantan, Pahang and Rompin rivers, possibly due to land-based anthropogenic activities, automotive emission and gas industries. However, the average Igeo and mCd values indicate that the heavy metals of the surface sediments are uncontaminated in all sampling stations. The same situation was true for trace elements, except for Hf which has the enrichment factor greater than 2 in EC8 station. The high concentration of Hf at this station was a natural occurring because of it has negative correlation with Zn in this station similarity with those in nature. Shale averages and chondorite normalized were used to normalize rare earth elements (REEs). Ce was found anthropogenic element, possibly due to occurrence of +4 oxidation states, while other REEs are of non-anthropogenic sources. Most REEs have lower concentrations at the larger river systems and Ce and Eu anomalies occurred in samples taken from the mouths of Kelantan and Pahang rivers. For major elements, Al, Ca, Mg, Na, and Ti were of anthropogenic sources, possibility due to tropical weathering. Both actinides Th and U were non-anthropogenic for all sampling stations except for Kuala Dungun possibility due to a radioactive related factory like among in that area. For the vertical element distribution, heavy metals As, Cd and Pb; trace elements Br, Hf, Sr and Zr; major elements Ca and Na and actinide element Th were of anthropogenic sources. However, by considering the average Igeo and mCd values, most of the layers in the east coast of Peninsular Malaysia were uncontaminated. Only Hf was the most polluted in affected stations and were classified as moderately to stronger contamination. The chondrite-normalized ratios of REEs showed LREEs enrichment and flat HREE depletion. No Ce anomaly was observed in sediments of all layers in all the stations. Overall, the results showed that the normalized patterns of REEs of the core sediments followed a general pattern of REEs of the world

Rare earth elements distribution in marine sediments of Malaysia coasts

In the east coast Peninsular Malaysia region, sediments are transported by several rivers from the east Malaysia into the South China Sea estuary. In the vicinity of the five river estuaries core sediments were collected in order to investigate rare earth elements (REEs) profile. Core sediments were divided into strata of between 2 to 4 cm intervals and prepared for analyzing by ICP-AES. REE concentrations of 54.3 μg/gr at 24–26 cm in EC4 increased to 114.1 μg/gr at 20–22 cm in EC5. The measured concentration of LREEs and Fe normalized enrichment factors indicated that sediments were not enriched with light rare earth elements derived from effluents of anthropogenic activities. Results of the total concentration were used to establish baseline data in environmental pollution assessment and to develop the correlations between the Ce/Ce* and Eu/Eu* anomalies and the distribution patterns of some light rare earth elements (LREEs) and the heavy rare earth elements (HREEs). The chondrite-normalized ratios of REEs showed LREEs enrichment and flat HREE depletion

Vertical distribution of heavy metals and enrichment in the South China Sea sediment cores.

Forty seven sediment cores recovered from the South China Sea coasts along the east coast of Peninsular Malaysia were analysed for As, Cd, Cr, Cu, Hg, Ni, Pb and Zn using instrumental neutron activation analysis. The results indicate a homogeneous distribution except for As and Pb in all stations. Assessment of heavy metal pollution in marine sediments requires knowledge of pre-anthropogenic metal concentrations to act as a reference against which measured values can be compared. Primitive values for the cored sediments were determined from shale average metal. Various methods for calculating metal enrichment and contamination factors are reviewed in detail and a modified and more robust version of the procedure for calculating the degree of contamination is proposed. The revised procedure allows the incorporation of a flexible range of pollutants, including various organic species, and the degree of contamination is expressed as an average ratio rather than an absolute summation number. Comparative data for normalized enrichment factors and the modified degree of contamination show that the South China Sea sediments are in uncontaminated to moderately contaminated level of heavy metal contamination. Compared to obtained values the Kelantan and Pahang big rivers mouth show higher enrichment averaged across other sites

Distribution of heavy metals in surface sediments from the South China Sea ecosystem, Malaysia

The concentrations of arsenic, cadmium, chromium, copper, mercury, nickel, lead and zinc in surface sediments collected from the east coast of peninsular Malaysia, along the South China Sea, were measured by two methods instrumental neutron activation analysis and inductively coupled plasma mass spectroscopy. The obtained results were use to determine the areal distribution of the metals of in the east coast of peninsular Malaysia and potential sources of these metals to this environment. The geochemical data propose that most of the metals found in the east coast of peninsular Malaysia constitute a redistribution of territorial materials within the ecosystem. Then, the metal concentrations can be considered to be present at natural background levels in surface sediments

Facile synthesis of ZnS/CdS and CdS/ZnS core-shell nanoparticles using microwave irradiation and their optical properties

ZnS/CdS and CdS/ZnS core shell nanoparticles with tunable shell thickness were synthesized via a two steps route under microwave irradiation. In the first step core nanoparticles were prepared using polyol method, and in the second step capping process of shells were performed at moderate temperature by choosing ethanol as a solvent. The thickness of the shells was controlled by adjusting the concentration of core nanoparticles and shell precursors. The structural and chemical characterizations were performed using X-ray diffraction, energy dispersive X-ray spectroscopy and transmission electron microscopy which provide direct evidence for shell growth. The structures of ZnS/CdS and CdS/ZnS core shell nanoparticles were similar to the cubic and hexagonal core structures, respectively. The optical properties of obtained core shell nanoparticles were characterized using UV-Visible and photoluminescence spectroscopy. The absorption edge of ZnS/CdS core shells shows a red shift compared to ZnS (core) while for CdS/ZnS, the absorption edge shows a blue shift compare to CdS (core) owing to the size effect and the potential-well effect. The emission peaks of ZnS/CdS and CdS/ZnS core shell nanoparticles in the range of 400-650 nm are from sulfur, zinc and cadmium vacancy defects and created surface states at ZnS/CdS and CdS/ZnS interfaces

Enhancement of visible light photocatalytic activity of ZnS and CdS nanoparticles based on organic and inorganic coating

Coating of ZnS and CdS nanoparticles with organic and inorganic materials can extend their light absorption in the visible region and their stability against photo-corrosion. Such materials could emerge as excellent photocatalysts for the elimination of pollutants from aqueous media using solar energy. In this study, PVP (polyvinyl pyrrolidone)-capped ZnS and CdS nanoparticles, ZnS/CdS and CdS/ZnS core shell nanoparticles were synthesized by microwave irradiation method and characterized using different techniques. The XRD patterns exhibited cubic and hexagonal structures for coated ZnS and CdS nanoparticles, respectively. Morphological evaluation of TEM images showed that the nanoparticles are generally spherical in shape. The UV–visible spectra confirmed a shift in the band gap of coated nanoparticles to longer or shorter wavelengths due to size and potential-well effects. The photocatalytic activity of nanoparticles toward dye degradation under visible light was found to be improved after coating. PVP-capped ZnS and CdS exhibited an enhancement in the initial methylene blue degradation efficiency by a factor of about 1.3. ZnS nanoparticles coated by CdS displayed the initial efficiency 3.2 times higher than bare ZnS. The maximum dye removal was obtained in presence of CdS/ZnS core shells which is 1.4 times more efficient than bare CdS

Thermoluminescence behavior of KClXBr1−X: in mixed crystals exposed to gamma radiation

In-doped KClXBr1−X (X=1, 0.75, 0.5, 0.25 and 0) mixed crystal has been grown by the Czochralski method. The segregation coefficient of In was studied by the inductively coupled plasma atomic emission spectrometry (ICP-OES). The crystal structure has been determined using X-ray diffraction (XRD) analysis. The thermoluminescence (TL) characterization of KClXBr1−X mixed crystals, exposed to gamma radiation has been performed. The results show the introduction of the dopants ions induced changes in the TL glow curve structure. The TL results suggest that doped KClXBr1−X mixed crystal has good potential active dosimeter applications for gamma ray irradiation

Phase controlled monodispersed CdS nanocrystal synthesized in polymer solution using microwave irradiation

Cadmium sulfide (CdS) nanocrystals were synthesized in aqueous solution of polyvinyl pyrrolidone (PVP) via the simple and rapid microwave irradiation method. It is revealed that sulfur source is a key factor in controlling the phase formation of the resulting nanocrystals. The hexagonal and cubic structure of CdS nanocrystals could be obtained with varying sulfur sources of thioacetamide and sodium sulphide respectively. The interaction mechanism of PVP with precursor ions of cadmium and sulfur sources in the preparation process was proposed. It is found that PVP compounded the CdS nanoparticles and protected them from agglomerating. With increasing of PVP concentration, the average particle size of CdS nanocrystals increased and subsequently their optical band gap decreased. At the appropriate dosage of PVP, well isolated nanoparticles with relatively narrow size distribution were obtained for both sulfur sources. Moreover the stability of CdS nanoparticles enhanced after coating with polymer

Luminescence properties and kinetic parameters of nanocrystalline BaxSr1-xSO4:Dya%,Tbb% powder under gamma excitation

In this study, nanocrystalline barium strontium sulfate complex BaxSr1-x(=0.12,0.50,0.88,0.94)SO4:Dya(=0.1,0.2,0.5,1.5%),Tbb(=0.2,0.4,1,1.5%) powders were prepared via a chemical co-precipitation method at room temperature. The nanocrystalline powders were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, UV–visible spectrometry, thermoluminescence (TL), and photoluminescence. Under gamma ray irradiation, the maximum intensity of the TL glow curves for BaxSr1-xSO4:Dy0.1%,Tb0.2% was obtained with x = 0.88. The nanocrystalline Ba0·88Sr0·12SO4:Dy1.5%,Tb1% powder was selected because of its high intensity glow curve with a good shape. The TL response of Ba0·88Sr0·12SO4:Dy1.5%,Tb1% after irradiation with different gamma doses exhibited linear behavior from 0.01 to 7 kGy and 1–15 kGy. A glow curve deconvolution method and MATLAB software were used to calculate the TL kinetic parameters and the results obtained were investigated in detail. Moreover, the emission spectra obtained for the Ba0·88Sr0·12SO4:Dy1.5%,Tb1% and Ba0·88Sr0·12SO4:Dy0.5%,Tb1.5% nanocrystalline powders at an excitation wavelength of 350 nm showed that the efficiency of the energy transfer from Dy3+ to Tb3+ ions was increased by increasing the Tb3+ ion concentration in Ba0·88Sr0·12SO4

INAA to determine trace element concentrations in the hair of street children of Isfahan city, Iran

This study aimed to assess trace element concentrations in the hair of street children. Nutritional status was assessed by 24 hours’ dietary recall and anthropometric measurements. Data analysis found that Br, Sc, Sm and Ti concentrations show a normal distribution, and there is no significant difference between street children and control group. However, in the street children’s hair, the levels of Au, U, V are decreased and the levels of Co, La, Sb, Th are increased compared to the control group