Surface ozone or tropospheric ozone has been recognized as one of the major factors that can give adverse impact on crops including rice plants. Effects of ozone on rice plants could be seen in decreased of biochemical activities and physiological performance which contribute to yield reduction. In Malaysia, surface ozone is on the rise due to increment anthropogenic sources i.e. urbanization, transportation and also industrialization process. This condition is alarming due to the facts that rice is the major staple food to the majority of Malaysian population. In this study, exceedence of ozone exposure above an hourly threshold concentration of 40 ppb (AOT40) and ozone trends in four major rice growing areas in Malaysia were assessed using time series analysis of ozone data recorded in each area from January 2000 until December 2010 with a total of 132 readings. The results showed a steady increase in exceedence ozone of yearly AOT40 and statistical significant upward trend for ozone concentrations in each rice growing area in Malaysia. This finding was particularly alarming because ozone is able to inhibit production of rice yields. Preventive actions need to be implemented as soon as possible in order to alleviate ozone threat to our national food security agenda.
Kajian ini adalah mengenai peranan sterol sebagai penunjuk bio-lipid untuk mengenal pasti variasi dan sumber bahan organik yang hadir bersama sedimen permukaan dari Kuala Selangor, Selangor. Kajian melibatkan kaedah pengekstrakan sterol daripada sampel sedimen dan seterusnya dianalisis menggunakan GC-MS untuk menentukan kehadiran sebatian tersebut. Sepuluh sebatian sterol dikenal pasti hadir dengan fitosterol merupakan sebatian dominan di kawasan kajian iaitu 79% daripada jumlah keseluruhan sterol. Ini diikuti oleh kolesterol serta sterol kumbahan masing-masing menyumbangkan 6% daripada jumlah keseluruhan sterol manakala selebihnya berada dalam julat 1-5%. Indeks Sumber Sterol (SSI) juga menunjukkan kandungan fitosterol yang tinggi walaupun hadir pada kadar yang berbeza di setiap stesen pensampelan. Penilaian pencemaran kumbahan menggunakan nisbah koprostanol/kolesterol, koprostanol/(koprostanol+kholestanol) serta epikoprostanol/koprostanol menunjukkan kawasan kajian tidak mengalami pencemaran kumbahan walaupun sterol daripada sumber kumbahan hadir di persekitarannya. Kesimpulannya sedimen permukaan di Kuala Selangor, Selangor mengandungi campuran sterol daripada pelbagai sumber yang hadir di persekitarannya dengan didominasi oleh fitosterol yang berasal daripada tumbuhan terestrial.
Biomass burning is one of the main sources of air pollution in South East Asia, predominantly during the dry period between June and October each year. Sumatra and Kalimantan, Indonesia, have been identified as the regions connected to biomass burning due to their involvement in agricultural activities. In Sumatra, the Province of Riau has always been found to have had the highest number of hotspots during haze episodes. This study aims to determine the concentration of five major pollutants (PM10, SO2, NO2, CO and O3) in Riau, Indonesia, for 2006 and 2007. It will also correlate the level of air pollutants to the number of hotspots recorded, using the hotspot information system introduced by the Malaysian Centre for Remote Sensing (MACRES). Overall, the concentration of air pollutants recorded was found to increase with the number of hotspots. Nevertheless, only the concentration of PM10 during a haze episode is significantly different when compared to its concentration in non-haze conditions. In fact, in August 2006, when the highest number of hotspots was recorded the concentration of PM10 was found to increase by more than 20% from its normal concentration. The dispersion pattern, as simulated by the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), showed that the distribution of PM10 was greatly influenced by the wind direction. Furthermore, the particles had the capacity to reach the Peninsular Malaysia within 42 hours of emission from the point sources as a consequence of the South West monsoon.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants with toxic effects and adverse health impacts on general population. Several methods of extraction had been applied to extract PAHs from human blood samples such as solid phase extraction (SPE). The SPE represents one of the most common techniques for extraction and clean-up procedures as it needs low quantity of solvents with less manual efforts. Similarly, various analytical instruments like gas chromatography coupled to mass spectrometry (GC-MS) was used to measure the PAHs levels. Gas chromatog- raphy is a simple, fast, and very efficient method for solvents and small organic molecules. This review provides an overview of the measured concentrations of PAHs in human blood samples through the application of SPE and GC- MS during the last ten years. While these studies used various solvents, their application of SPE method and GC-MS revealed rewarding results about the determination of PAHs levels in the human samples.
Fine particulate matter (aerodynamic diameter ≤2.5 μm) (PM2.5) has become a major concern because it can adsorb chemicals e.g. polycyclic aromatic hydrocarbons (PAHs) onto its surface. Although PAHs are priority pollutants that can cause adverse health effect, there is still limited information concerning indoor exposures to PAHs in Malaysia. This study aimed to characterise the distribution of PAHs bounded to PM2.5in primary school environments. Indoor and outdoor PM2.5 were collected between May and July 2017 using low volume samplers (LVS) at three public primary schools in the Federal Territory of Kuala Lumpur. PAHs were extracted by ultrasonic extraction with Dichloromethane: n-Hexane (1:1, v/v) as the extraction solvent and analysed using gas chromatography coupled with mass spectrometer (GC-MS). Based on the results, the average total concentration of PAHs (∑PAHs) ranged from 3.8 to 10.1 ng m-3and 1.6 to 8.0 ng m-3for outdoors and indoors, respectively. PAHs in PM2.5samples indicated the potential contribution of combustion at high temperature and indoor sources and the infiltration of outdoor PAHs were the important sources for outdoor and indoor, respectively. In addition, the diagnostic ratio analysis showed that vehicular emissions were the most predominant sources of PAHs in school environments.
There are several alternative sampling and analytical methods available for the determination of respirable
crystalline silica exposure among workers. The commonly used ones are, (1) NIOSH Manual Analytical Method
No.7500(NMAM 7500) which is Silica, crystalline, by X-ray difractometer via filter deposition(NIOSH 2003), and
(2) MDHS 101 (Methods for the Determination of Hazardous Substances (MDHS) Guidance No.101: Respirable
crystalline silica in respirable airborne dust). The aim of this study is to compare applicability of respirable crystalline
silica sampling and analysis between method MDHS 101 and NMAM 7500. Laboratory procedures will be performed
strictly based on MDHS 101 and NMAM 7500. Both methods apply X-ray diffraction as analytical technique with
many variations on sampling techniques and laboratory preparations. Quality assurance values such as detection
limits, accuracy and precision are derived from both data and will be compared to determine which of the method
establishes better quality assurance. The method which establishes better quality assurance will be recommend to be
used in Malaysian respirable crystalline silica monitoring programme. The strength of this research lies on its potential
to provide local capabilities in analysis of respirable crystalline silica in Malaysian setting.
This study explores the role of sterols as lipid biomarkers to indicate their input which originates from various sources in the marine environment. Sterols and their ratios were investigated in sediments taken from sixteen sampling stations at Pulau Tinggi, Johor in order to assess the sources of organic matter. The compounds extracted from the sediments were quantified using a gas chromatography-mass spectrometry (GC-MS). The distributions of sterols indicated that organic matter at all sampling stations originated from a mixture of marine source and terrestrial origins at different proportions. A total of eleven sterols were quantified, with the major compounds being phytosterols (44% of total sterols), cholesterol (11%), brassicasterol (11%) and fecal sterols (12%).
Kandungan alkohol lemak di dalam 19 sampel sedimen permukaan di Sungai Sepang Besar, Sepang, Selangor telah dianalisis menggunakan kromatografi gas-spektrometer jisim (GC-MS). Sebanyak 19 sebatian alkohol lemak dengan julat kepekatan 0.02 μg/g – 9.01 μg/g berat kering dikenalpasti yang terdiri daripada alkohol lemak C12 sehingga C30 termasuk 4 sebatian bercabang. Alkohol lemak C26 mendominasi kebanyakan stesen persampelan dengan julat 0.29 – 5.43 μg/g berat kering, iaitu 15.5% daripada jumlah alkohol lemak. Berdasarkan kepekatan individu sebatian alkohol lemak dan nisbah [Σ(C12 - C20)/Σ(C22 - C30)], Sungai Sepang Besar boleh dikatakan mengandungi alkohol lemak berantai pendek (C12 - C20) yang tinggi berasal daripada organisma marin. Walau bagaimanapun, nilai Indeks Sumber Alkohol (ASI) tidak menunjukkan Sungai Sepang Besar didominasi oleh alkohol lemak rantai pendek kerana faktor kandungan sebatian C26 yang tinggi di kebanyakan stesen persampelan. Nilai nisbah alkohol lemak (rantai ganjil)/(rantai genap) adalah tinggi bagi hampir kesemua stesen persampelan yang dipengaruhi oleh aktiviti bakteria yang tinggi. Dengan itu dapat disimpulkan bahawa sedimen permukaan Sungai Sepang Besar mengandungi campuran bahan organik yang berasal dari marin, terestrial dan bakteria.
This study was conducted to investigate the batch and fixed-bed adsorption properties of boron on curcumin-impregnated activated carbon (Cur-AC). The maximum boron removal was obtained at pH5.5 and 120 min of contact time. Langmuir and Freundlich isotherm models were applied and it was determined that the experimental data conformed to both models. The Langmuir maximum adsorption capacities for Cur-AC (5.00 mg/g) and regenerated Cur-AC (3.61 mg/g) were obviously higher than the capacity for bare activated carbon (0.59 mg/g). Kinetic studies indicated the adsorption of boron conformed to the intra-particle model. The highest boron removal in fixed-bed column adsorption was achieved up to 99% for the first 5 min at an inlet concentration of 890 mg/L and a flow rate of 8.0 mL/min. Thomas and the Yoon-Nelson models gave better fit to the experimental data. Cur-AC can be reused after elution processes with slightly lower adsorption capacity.
Kandungan sebatian alkohol lemak di dalam tujuh sampel sedimen permukaan dari muara Sungai Kapar, Selangor telah dikenal pasti menggunakan gas kromatografi-spektrometri jisim (GC-MS) dan hasilnya menunjukkan wujudnya 13 sebatian alkohol lemak (C12- C24) termasuk enam sebatian bercabang (-iso dan -anteiso) hadir. Secara keseluruhannya, sampel yang dikaji terdiri daripada 65% alkohol lemak rantai pendek (C12- C20) yang dihasilkan oleh organisma marin manakala 14% adalah alkohol lemak rantai panjang (C21- C24) yang berpunca daripada tumbuhan terestrial dan selebihnya merupakan sebatian bercabang yang dihasilkan oleh proses metabolisme bakteria. Sebatian C16 mendominasi kesemua stesen pensampelan dengan julat kepekatan 29.69-164.35 μgg-1 berat kering iaitu 32% daripada jumlah keseluruhan alkohol lemak. Nisbah antara alkohol lemak rantai pendek dan rantai panjang [Σ(C12- C20)/Σ(C21- C22)] bagi setiap stesen pensampelan memberikan nilai >1, menunjukkan kandungan alkohol lemak rantai pendek sumber marin adalah lebih tinggi daripada kandungan alkohol lemak rantai panjang. Indeks Sumber Alkohol (ASI) pula diguna untuk menganggar kesan input alkohol lemak terestrial ke dalam sedimen marin berdasarkan nisbah alkohol lemak C22/C14 menunjukkan stesen Kp1, Kp2, Kp5 dan Kp6 mempunyai nilai >1; iaitu kandungan C22 adalah lebih tinggi berbanding C14. Walau bagaimanapun, nisbah C22/C16 memberikan hasil yang sebaliknya dengan kesemua stesen didominasi oleh C16 berbanding C22. Kajian ini menunjukkan alkohol lemak (C12- C20) terutamanya sebatian C16 mendominasi kawasan muara Sungai Kapar, Selangor berbanding alkohol lemak rantai panjang (C21- C24).
Surfactants in the atmosphere may act as cloud condensation nuclei, with a potentially negative impact on the global climate. Therefore, accurate determination of surfactants is crucial in order to investigate the possible effects of surfactants on the atmosphere. The aim of this study was to identify the optimum sampling method for measuring the maximum quantity of surfactants present in ambient air. Air samples were collected using a range of air sampling pumps that were made to vary in terms of flow rate, storage period, type of absorbing solution and the characteristics of the impinger tube. Samples obtained were analysed by colourimetry for anionic and cationic surfactants as methylene blue-active substances (MBAS) and disulphine blue-active substances (DBAS), respectively. Absorbance was measured at 650 nm for MBAS and 628 nm for DBAS using UV-visible spectrophotometer. We found that the optimum sampling method consisted of an absorbent solution (deionised water, buffer solution and methylene blue/disulphine blue solution) with the flow rate of 1.0 L/min. The concentration of surfactants in all sampling methods remained constant regardless of the storage period (1 day and 4 days), indicating that surfactants in the absorbing solution are quite stable. Covering the impinger tube was shown to influence the amount of both anionic and cationic surfactants detected.
The air pollution index (API) has been recognized as one of the important air quality indicators used to record the
correlation between air pollution and human health. The API information can help government agencies, policy makers
and individuals to prepare precautionary measures in order to eliminate the impact of air pollution episodes. This study
aimed to verify the monthly API trends at three different stations in Malaysia; industrial, residential and sub-urban areas.
The data collected between the year 2000 and 2009 was analyzed based on time series forecasting. Both classical and
modern methods namely seasonal autoregressive integrated moving average (SARIMA) and fuzzy time series (FTS) were
employed. The model developed was scrutinized by means of statistical performance of root mean square error (RMSE).
The results showed a good performance of SARIMA in two urban stations with 16% and 19.6% which was more satisfactory
compared to FTS; however, FTS performed better in suburban station with 25.9% which was more pleasing compared
to SARIMA methods. This result proved that classical method is compatible with the advanced forecasting techniques in
providing better forecasting accuracy. Both classical and modern methods have the ability to investigate and forecast
the API trends in which can be considered as an effective decision-making process in air quality policy.
Kajian yang dijalankan ini bertujuan untuk menilai indeks kualiti air di sekitar kawasan lombong di Sungai Pelepah Kanan, Kota Tinggi, Johor. Sebanyak enam stesen pensampelan telah dipilih dari bahagian hulu ke hilir sungai ini untuk menilai indeks kualiti air di sepanjang sungai tersebut. Tiga replikasi sampel telah diambil daripada setiap stesen pensampelan. Pengambilan sampel dilakukan pada dua musim yang berbeza iaitu musim kering (Julai) dan musim hujan (Disember) 2007. Parameter in-situ yang ditentukan dalam kajian ini ialah suhu, pH, oksigen terlarut (DO) dan konduktiviti. Parameter ex-situ yang dianalisis dalam makmal ialah turbiditi air, jumlah pepejal terampai (TSS), keperluan oksigen biokimia (BOD), keperluan oksigen kimia (COD) dan ammonia nitrogen (NH3-N). Berdasarkan Piawaian Interim Kualiti Air Kebangsaan Malaysia (INWQS) hasil kajian yang diperolehi menunjukkan semua stesen pensampelan di Sungai Pelepah Kanan pada bulan Julai berada dalam kelas I kecuali oksigen terlarut dan pH berada dalam kelas II. Selain itu, hasil kajian pada bulan Disember juga menunjukkan semua parameter fiziko-kimia berada dalam kelas I-II kecuali pH berada dalam kelas III. Ujian korelasi menunjukkan terdapat hubungan bererti antara parameter-parameter fiziko-kimia yang di tertentukan. Analisis Indeks Kualiti Air (IKA) menunjukkan nilai purata IKA pada bulan Julai adalah 96.88 (kelas I) manakala pada bulan Disember telah merosot ke 84.03 (kelas II). Berdasarkan kepada nilai IKA dan perbandingan dengan INWQS, indeks kualiti air Sungai Pelepah Kanan adalah berada pada tahap yang bersih dan kurang mengalami pencemaran yang serius daripada aktiviti antropogenik mahupun pencemaran secara semula jadi.
The individual compounds and sources of polycyclic aromatic hydrocarbon (PAHs) were studied in the surface sediments
at 32 locations in the tourism area of Langkawi Island. A total of 15 PAHs were determined and quantified by gas
chromatography coupled with mass spectrometry (GC-MS). The total PAH concentrations of surface sediments from
Langkawi Island ranged from 228.13 to 990.25 ng/g and they were classified as being in the low to moderate pollution
range. All sampling stations were dominated by high molecular weight PAHs with 4 rings (31.59%) and 5-6 rings (42.73%).
The diagnostic ratio results showed that in most cases, the sampling stations have pyrogenic input. Further analysis
using principal component analysis (PCA) combined with absolute principal component score (APCS) and multiple linear
regression (MLR) showed that the natural gas emissions contributed to 57% of the total PAH concentration, 22% from the
incomplete combustion and pyrolysis of fuel, 15% from pyrogenic and petrogenic sources and 6% from an undefined source.