Norhayati Tahir - Academia.edu (original) (raw)

Papers by Norhayati Tahir

A study has been conducted to investigate the distribution of aliphatic and polycyclic aromatic h... more A study has been conducted to investigate the distribution of aliphatic and polycyclic aromatic hydrocarbons in Environmental Tobacco Smoke (ETS). ETS is the smoke that is present in the ambient air due to smoking of tobacco. Types of cigarettes (C1R1 and C6R1) were chosen based on a result of a simple survey carried out to determine the consumer's choice of cigarette brand. In analyzing the ETS, volunteers were asked to smoke each brand of cigarette in a closed room and the ETS was then collected using the High Volume Air Sampler fitted with a glass fiber filter. Smoke samples from the glass fiber filter were then extracted using Ultrasonic Agitation and fractionated into aliphatic and aromatic fraction using silicaalumina column. Identification and quantification was done using gas chromatography with flame ionization detector. Results indicated the presence of n-alkanes in ETS, ranging from C 13 to C 36 with an odd to even carbon number predominance with Carbon Preference Index (CPI) values ranging from 3.34 to 4.90. Total identified resolved aliphatic hydrocarbons (TIRAH) concentration found in ETS ranged from 590 µg m-3 to 591 µg m-3 with the percentage of plant wax n-alkanes ranging from 61% to 64% of the TIRAH found in ETS samples. In source apportionment, CPI > 1 and high percentage of plant wax n-alkanes has generally been associated with the contribution of terrestrial plant source, thus this result indicates that even after curing process and smoking of tobacco, the overall signature of the source of n-alkanes is still preserved. Amount of PAHs detected in all ETS samples ranged from 11.7 ng m-3 to 56.1 ng m-3. Results also indicated the presence of medium to high molecular weight PAHs with dominant presence of benzo[g,h,i]perylene compound. This result seems to support the contention that smoking process involves a high temperature burning with an oxygen deficient zone in the cigarette itself. Although the concentrations were low, the carcinogenic and mutagenic PAHs were still present in the respective ETS making the passive smokers vulnerable to diseases resulted from exposure to PAHs. Abstrak Satu kajian telah dijalankan bagi mengenalpasti taburan hidrokarbon alifatik dan polisiklik aromatik di dalam Asap Tembakau Sekitaran (ATS). ATS adalah asap yang hadir di dalam udara sekitaran berikutan wujudnya aktiviti merokok. Jenis rokok (C1R1 dan C6R1) telah dipilih berdasarkan daripada jawapan soalselidik yang dijalankan bagi menentukan jenis jenama rokok pilihan pengguna. Bagi menganalisa ATS ini, sukarelawan diminta untuk merokok setiap jenis jenama rokok yang dipilih, di dalam bilik yang tertutup. ATS kemudiannya dikumpul menggunakan alat Persampelan Udara Berisipadu Tinggi yang dimuatkan dengan penapis gentian kaca. Sampel asap daripada penapis gentian kaca in kemudiannya diekstrak menggunakan teknik goncangan Ultrasonikasi dan dipisahkan kepada kumpulan alifatik dan aromatik dengan menggunakan turus silika-alumina. Pencirian dan kuantifikasi telah dilakukan menggunakan kromatografi gas dengan pengesan pengionan nyalaan. Keputusan menunjukkan kehadiran unsur n-alkana di dalam ATS yang berada dalam lingkungan C 13 hingga C 36 dan didominasi oleh nombor karbon ganjil berbanding genap. Nilai Indeks Pemilihan Karbon (IPK) berada dalam julat 3.34 hingga 4.90. Kepekatan Jumlah Hidrokarbon Alifatik Terpisah Dikenalpasti (JHAPK) yang wujud dalam ATS berada dalam lingkungan 590 µg m-3 hingga 591µg m-3 dengan peratus lilin tumbuhan dalam julat 61% hingga 64%. Bagi pembahagian sumber, IPK > 1 dan peratus lilin tumbuhan yang tinggi sering dikaitkan dengan sumbangan oleh sumber tumbuhan daratan. Justeru, keputusan ini menunjukkan bahawa tanda pencirian bagi sumber n-alkana masih terpelihara walaupun selepas proses rawatan dan hisapan rokok tembakau. Kadar kepekatan hidrokarbon polisiklik aromatik (HPA) yang dikesan dalam sampel ATS berada dalam julat 11.7 ng m-3 hingga 56.1 ng m-3. Keputusan juga menunjukkan kehadiran berat molekul sederhana hingga besar di mana benzo[g,h,i]perylene merupakan komponen utama yang wujud dalam setiap sampel. Keputusan ini menyokong pendapat bahawa proses merokok melibatkan pembakaran bersuhu tinggi dengan kewujudan zon kurang oksigen di dalam rokok itu sendiri. Walaupun kepekatannya adalah rendah, HPA yang karsinogenik dan mutagenik ini masih hadir di dalam ATS. Ini menjadikan perokok pasif masih berpotensi kepada penyakit-penyakit akibat terdedah kepada HPA.

Hidrolisis klorpirifos (O,O-diethyl-O-3,5,6-trichloro-2-pyridyl phosphorothionate) telah dikaji d... more Hidrolisis klorpirifos (O,O-diethyl-O-3,5,6-trichloro-2-pyridyl phosphorothionate) telah dikaji dalam media akues pada suhu dan keadaan pH yang berbeza. Pemalar kadar dan jangka hayat separa yang diperolehi menunjukkan bahawa klorpirifos lebih stabil dalam keadaan berasid. Kadar degradasi meningkat apabila nilai pH bertambah. Suhu juga mempengaruhi kadar hidrolisis. Hidrolisis klorpirifos dalam air mematuhi tindak balas tertib pertama. Jangka hayat separa klorpirifos dalam larutan akues adalah pendek (di antara 4.57 hingga 14.0 hari), dan ianya bergantung pada kepekatan asal klorpirifos dan jenis larutan akues. Kadar degradasi adalah perlahan dalam larutan 0.02M CaCl 2 dengan kepekatan asal klorpirifos yang tinggi. Perbandingan antara kadar hidrolisis dalam laruatan air steril dan tidak steril tidak menunjukkan peranan biodegradasi yang ketara dalam air tidak disteril. Keputusan ini menunjukkan bahawa parameter pH sahaja tidak mencukupi untuk menjangkakan kadar hidrolisis klorpirifos.

Environmental Science and Pollution Research, Oct 11, 2021

Surface sediments along the Southern Terengganu coast (≤7 km from the coast) were analyzed for po... more Surface sediments along the Southern Terengganu coast (≤7 km from the coast) were analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of 16 USEPA priority polycyclic aromatic hydrocarbons (ΣPAH16) ranged from 2.59 to 155 ng g−1 and their respective alkylated ranged between 8.80 and 24.90 ng g−1. Traces of acephenanthrylene, benzo[c]phenanthrene, thiophenic PAH, and benzonaphthofuran were identified. PAH diagnostic ratios and cross-plots revealed that these sedimentary PAH compounds are derived mainly from pyrogenic sources, primarily from biomass burning and petroleum combustion residues with minor petrogenic input. The high correlations between pyrogenic PAHs to total PAHs (r >0.73, p <0.5), and the Bap/Bep ratio to total PAHs (r = 0.88, p <0.5), suggest that atmospheric deposition and urban runoff are the main deposition pathways. The concentrations of the PAHs in the southern South China Sea fall in the moderate contamination range of 100–1000 ng g−1.

This study was carried out to determine the concentration and distribution of polycyclic aromatic... more This study was carried out to determine the concentration and distribution of polycyclic aromatic hydrocarbons (PAHs) in soils of Kota Bharu, Kelantan Darul Naim. A total of 20 sampling sites were chosen covering the town center and surrounding suburban area of this district. PAHs in soil matrix were extracted using ultrasonic agitation technique with dichloromethane as extraction solvent. Fractionation of PAHs were done using silica-alumina column and the characterization of these individual components were carried out using GCMS. Priority PAHs (PAH 16 as defined by the U.S. Environmental Protection Agency) were predominantly represented by four to six ring compounds with concentration ranging between 0.022 µgg-1 to 24.06 µgg-1. Based on ratios of selected molecular markers, it can be concluded that PAHs in soil were generally derived from combustion sources. A strong correlation between benzo (g,h,i)perylene with total identified PAHs strongly suggest that vehicular emission is the major constituent of this combustion sources.

Sains Malaysiana, Sep 30, 2017

This study investigates the spatial variation of water quality parameters in Sungai Setiu Basin a... more This study investigates the spatial variation of water quality parameters in Sungai Setiu Basin at ten different locations from March 2010 to February 2011. The water quality was assessed using the Water Quality Index by Malaysian Department of Environment (DOE-WQI) and classified according to the Malaysia Interim National Water Quality Standard (INWQS). Six water quality parameters embedded in the DOE-WQI were dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), pH, ammoniacal nitrogen (AN) and total suspended solid (TSS). In addition, this study also examined the changes in water quality over the past 10 years by comparing the present water quality to the previous works. The overall mean WQI value obtained was 84.0 which indicate that the Sungai Setiu basin is in clean condition and all measured water quality parameters gave value within the permissible limits of the INWQS classification except for pH which fall in Class III. It can be concluded that water quality in Sungai Setiu does not varies greatly over a decade. Hence continuous monitoring is needed to improve the water quality and minimize water pollution.

Sains Malaysiana, Jul 1, 2015

Seasonal variations of dissolved and suspended particulate metals were observed. The results were... more Seasonal variations of dissolved and suspended particulate metals were observed. The results were compared with selected Malaysian national rivers, world average and established guidelines. In addition, the enrichment of suspended particulate metals and the partitioning of metals between dissolved and suspended particulate phases were discussed.

Sains Malaysiana, Sep 30, 2021

Sediment cores from the southern South China Sea off the Terengganu coast were analyzed for polyc... more Sediment cores from the southern South China Sea off the Terengganu coast were analyzed for polycyclic aromatic hydrocarbons (PAHs) and perylene. The concentrations of total 17 PAH (TPAHs) and perylene varied between 5.45-27.7 ng/g and 0.51-7.77 ng/g, respectively. Analyses of variance showed significant differences between the stations, but not in sub-bottom depths at the 0.05 level. The PAH cross plots showed a predominance of pyrogenic over petrogenic PAHs. Principal component analysis (PCA) showed clustered PAHs that are correlated with total organic carbon (TOC), indicating the importance of surface runoff via fluvial transport for contributing these PAHs to the coastal environment of the study area. Overall, the concentrations of PAHs in the study area are considered to be in the low range, not exceeding the 100 ng/g mark.

Sains Malaysiana, Jul 1, 2015

Three short sediment cores (12-32 cm) from South China Sea off Southern Terengganu were collected... more Three short sediment cores (12-32 cm) from South China Sea off Southern Terengganu were collected during May (post-Northeast monsoon) and September (pre-Northeast monsoon) 2007. The concentration of total organic carbon (TOC) obtained ranged from 0.41-2.23 and 0.38-2.31% during post and pre-monsoon, respectively. TOC concentration was found to decrease with depth and distance from the coast and river mouth. In particular, station with close proximity to the coast exhibits most pronounced variation of TOC with depth. Besides spatial variation, it is noted that the seasonal variations also considerably affect the distribution and concentrations of TOC, where both near and offshore sampling stations showed significant variations in TOC content during May and September sampling. These findings suggest the importance of terrestrial organic carbon flux, physical mixing and seasonal variations in regulating the concentration and distribution of the organic carbon in the study area.

Penjerapan insektisid klorpirifos (rumusan kormersil berjenama Kensban®, 20% bahan aktif) pada ti... more Penjerapan insektisid klorpirifos (rumusan kormersil berjenama Kensban®, 20% bahan aktif) pada tiga jenis siri tanah (0-25cm) dari kebun sayur-sayuran di negeri Terengganu, Malaysia telah dikaji menggunakan kaedah penjerapan kelompok. Analisis insektisid dijalankan menggunakan kaedah kromatografi gas dilengkapkan dengan pengesan nitrogen and fosforus. Keputusan menunjukkan bahawa tanah yang mengandungi lebih banyak jirim organik dan lempung mempunyai keupayaan menjerap insektisid yang lebih kuat. Selain itu, pH tanah juga mempengaruhi keupayaan penjerapan insektisid di mana penjerapan adalah lebih tinggi pada tanah yang mempunyai nilai pH yang rendah. Secara keseluruhannya, kandungan jirim organik , kandungan lempung dan pH memainkan peranan yang penting dalam penjerapan insektisid klorpirifos. Walau bagaimanapun, tidak boleh dinafikan bahawa keupayaan penjerapan yang diperolehi dalam kajian ini mungkin juga dipengaruhi oleh interaksi di antara klorpirifos, pelarut, pengemulsi, air dengan tapak penjerapan tanah memandangkan klorpirifos yang digunakan adalah formulasi komersil.

A study has been carried out to determine the concentration and distribution of polycyclic aromat... more A study has been carried out to determine the concentration and distribution of polycyclic aromatic hydrocarbons (PAHs) in urban soils of Kemaman, Terengganu. Surface soil samples (< 500 µm) were ultrasonicated using dichloromethane as solvent and the extracts fractionated on silica-alumina column. Detection and quantification of 16 priority PAHs compounds were carried out using GC-FID. With the exception of two stations, results generally indicated that the sum of 16 priority PAHs concentration (total PAHs) in soils ranged from to 6.3 to 176 µg/kg (dry weight); the two stations which exhibited significantly higher levels of total PAHs was at the main road junction located at the heart of the commercial centre of the town (535 µg/kg) and at an industrial estate, adjacent to a sawmill (547 µg/kg). Statistical analysis suggests that there is a significant difference in total PAHs concentration (p<0.05) with sampling sites. Most common PAHs compound observed in almost all the soil samples was BgP indicating the importance of vehicular emission as a source of PAHs in these soils. In addition, contribution of biomass burning to the presence of PAHs in these soils was also observed as indicated by a positive correlation between Benzo[a]pyrene with total PAHs.

PM 2.5 mass concentration and associated water-soluble ionic species in a suburban coastal area o... more PM 2.5 mass concentration and associated water-soluble ionic species in a suburban coastal area of Kuala Terengganu, Malaysia were investigated intermittently from year 2006 to 2009. A total of 78 weekly PM 2.5 samples were analyzed. The mass concentration of PM 2.5 exhibited annual, seasonal and diurnal variations. Temporal distributions of rainfall, sporadic haze episodes and local air flow (sea breeze circulation) were factors controlling PM 2.5 mass variations in the study area. Although the PM 2.5 concentrations were increased during haze episodes in 2006 (August and October) and 2007 (October), their concentrations however, were still within the international guidelines. The average concentration of individual ions was in decreasing trend; SO 4 2-> NH 4

Sains Malaysiana, Jun 30, 2017

The aim of this study was to assess spatial and seasonal variations of dissolved and particulate ... more The aim of this study was to assess spatial and seasonal variations of dissolved and particulate organic carbon (DOC and POC, respectively) in the Setiu Wetland, which is located in the southern region of the South China Sea coastal area. Surface water samples were collected monthly from October 2009-September 2010. In addition, the concentration of chlorophyll-a was determined. The DOC and POC mean concentration varied between 80-340 µM and 60-115 µM, respectively. The results showed that the concentrations of these parameters were mainly influenced by human activities and season. Higher concentrations of DOC (150-340 µM) and POC (75-115 µM) were found at stations near the populated area, aquaculture and palm oil plantation. In addition, higher concentrations of DOC (200-275 µM) and POC (105-150 µM) were also recorded during the monsoon season due to runoff from terrestrial sources and resuspension from bottom sediments. No significant correlation between the low molecular weight (LMW) fractions of DOC and chlorophyll-a (R 2 =0.0096, p>0.05) further supports the hypothesis that phytoplankton not playing key role in regulating the organic carbon distribution. Higher percentage of LMW DOC in monsoon season suggesting possible input of this fraction from land runoff to the wetland area.

Bulletin of Environmental Contamination and Toxicology, Jan 17, 2014

A short-term investigation on the chemical composition of rainwater was carried out at five selec... more A short-term investigation on the chemical composition of rainwater was carried out at five selected sampling stations in Kuantan district, Pahang, Malaysia. Sampling of rainwater was conducted by event basis between September and November 2011. Rainwater samples were collected using polyethylene containers and the parameters measured were cations (sodium, potassium, ammonium, calcium and magnesium) and anions (chlorides, nitrates and sulphates). The average pH value for rainwater samples was 6.0 ± 0.57 in which most of the sampling sites exhibited pH values [5.6. Calcium and sulphate were the most abundant cation and anion, respectively, whilst the concentrations of other major ions varied according to sampling location.

Sains Malaysiana, 2018

A study was carried out to determine the distribution and behaviour of nitrogen (N) compounds (ni... more A study was carried out to determine the distribution and behaviour of nitrogen (N) compounds (nitrite, nitrate, ammonia, dissolved and particulate organic nitrogen) in Sungai Terengganu estuary (TRE). Surface water samples were collected during ebb neap and spring tides for the longitudinal survey along the salinity gradient. The results indicated that all N compounds behave non-conservatively with addition during both tidal cycles, except for nitrate which exhibited removal behaviour during spring tide. In general, higher concentration of N compounds was observed during spring tide compared to neap tide. It is suggested that during spring tide, stronger water turbulence resulted in resuspension of nutrients in bottom sediment and lead to the increase in N compounds concentrations in the surface water. The diurnal survey for the freshwater station showed that the concentrations of N compounds follow the ebb and flood variations, whereas for the coastal station the reverse trend was observed. Comparisons with a previous study under similar tidal conditions show there was an increase in nitrite and ammonia concentrations in TRE, which was probably due to increase in discharge from the rapid development activities around this area. In addition, the presence of a breakwater at the lower part of the estuary may also contribute to the high nutrient content in the estuary due to restricted outflow of nutrients to the coastal area. Overall, the results from this study highlighted the importance of monitoring the N compounds for future protection of the estuary.

PLOS ONE, 2021

The reconstruction of fire history is essential to understand the palaeoclimate and human history... more The reconstruction of fire history is essential to understand the palaeoclimate and human history. Polycyclic aromatic hydrocarbons (PAHs) have been extensively used as a fire marker. In this work, the distribution of PAHs in Borneo peat archives was investigated to understand how PAHs reflect the palaeo-fire activity. In total, 52 peat samples were analysed from a Borneo peat core for the PAH analysis. Pyrogenic PAHs consist of 2–7 aromatic rings, some of which have methyl and ethyl groups. The results reveal that the concentration of pyrogenic PAHs fluctuated with the core depth. Compared to low-molecular-weight (LMW) PAHs, the high-molecular-weight (HMW) PAHs had a more similar depth variation to the charcoal abundance. This finding also suggests that the HMW PAHs were mainly formed at a local fire near the study area, while the LMW PAHs could be transported from remote locations.

Oriental Journal Of Chemistry, 2021

Aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were studied in two sediment c... more Aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were studied in two sediment cores of southern South China Sea off Johor coastal area. The concentrations of the total identified resolved aliphatic hydrocarbons (TiRAHs) in the coastal station (STC104) ranged from 0.35 to 2.07 µg/g while the offshore station (STC100) varied from 0.05 to 14.7 µg/g. The concentrations of total PAHs were varied from not detected to 33.9 ng/g. The nalkanes distribution in STC104 were predominant in short chain carbons from marine productivity, petroleum mixture and minor higher plant input, while STC100 exhibited a bimodal distribution with mixed input of marine and terrestrial origin. PAHs isomer ratios cross-plot have showed mixed input of pyrogenic and petrogenic inputs while perylene was dominated in STC100 followed by fossil fuels and pyrogenic source. Presence of perylene in both cores suggesting the contribution of biogenic sources. Principal component analysis was used to cluste...

Marine Pollution Bulletin, 2020

Sains Malaysiana, 2018

A seasonal study of phosphorus (P)-based nutrients was carried out in Sungai Setiu basin which is... more A seasonal study of phosphorus (P)-based nutrients was carried out in Sungai Setiu basin which is located in the southern region of the South China Sea (Malaysia) from July 2010 until June 2011. Parameters measured were dissolved inorganic P (DIP), dissolved organic P (DOP) and total particulate P (TPP). In addition, DOP concentration was size fractionated into high molecular weight (HMW, 0.7 µm-100 kDa), middle MW (MMW, 100-30 kDa) and low MW (LMW, <30 kDa). The results show that the mean concentration of P-based nutrients ranged between 3.2-7.0 µg/L P for DIP, 5.6-12.1 µg/L P for DOP and 9.2-119.4 µg/L P for TPP. Higher mean concentrations of P were recorded at urban and agricultural areas. In addition, the distribution of P was affected by season as higher mean concentrations of P were observed during the northeast monsoon due to the surface runoff of nutrients during this heavy raining season. The fractionation study of DOP further revealed that HMW fraction was abundant in Sungai Setiu, making up approximately 60% of the total DOP. This high percentage of HMW DOP was recorded at stations in the vicinity of agriculture area and towns suggesting an important contribution from anthropogenic activities. The LMW DOP fraction was not significantly associated with chlorophyll-a, suggesting that the phytoplankton might not be the predominant contributor for LMW fraction in this river. We suggest that these organic nutrient inputs should be monitored as part of the management of the aquatic system.

Chemosphere, 2019

This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) ... more This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) and assess the risk to health at different sites in Malaysia. Continuous monitoring of

Chemosphere, 2018

Distribution, sources and potential health risks of polycyclic aromatic hydrocarbons (PAHs) in PM... more Distribution, sources and potential health risks of polycyclic aromatic hydrocarbons (PAHs) in PM 2.5 collected during different monsoon seasons and haze episode in Kuala Lumpur, Chemosphere,

A study has been conducted to investigate the distribution of aliphatic and polycyclic aromatic h... more A study has been conducted to investigate the distribution of aliphatic and polycyclic aromatic hydrocarbons in Environmental Tobacco Smoke (ETS). ETS is the smoke that is present in the ambient air due to smoking of tobacco. Types of cigarettes (C1R1 and C6R1) were chosen based on a result of a simple survey carried out to determine the consumer's choice of cigarette brand. In analyzing the ETS, volunteers were asked to smoke each brand of cigarette in a closed room and the ETS was then collected using the High Volume Air Sampler fitted with a glass fiber filter. Smoke samples from the glass fiber filter were then extracted using Ultrasonic Agitation and fractionated into aliphatic and aromatic fraction using silicaalumina column. Identification and quantification was done using gas chromatography with flame ionization detector. Results indicated the presence of n-alkanes in ETS, ranging from C 13 to C 36 with an odd to even carbon number predominance with Carbon Preference Index (CPI) values ranging from 3.34 to 4.90. Total identified resolved aliphatic hydrocarbons (TIRAH) concentration found in ETS ranged from 590 µg m-3 to 591 µg m-3 with the percentage of plant wax n-alkanes ranging from 61% to 64% of the TIRAH found in ETS samples. In source apportionment, CPI > 1 and high percentage of plant wax n-alkanes has generally been associated with the contribution of terrestrial plant source, thus this result indicates that even after curing process and smoking of tobacco, the overall signature of the source of n-alkanes is still preserved. Amount of PAHs detected in all ETS samples ranged from 11.7 ng m-3 to 56.1 ng m-3. Results also indicated the presence of medium to high molecular weight PAHs with dominant presence of benzo[g,h,i]perylene compound. This result seems to support the contention that smoking process involves a high temperature burning with an oxygen deficient zone in the cigarette itself. Although the concentrations were low, the carcinogenic and mutagenic PAHs were still present in the respective ETS making the passive smokers vulnerable to diseases resulted from exposure to PAHs. Abstrak Satu kajian telah dijalankan bagi mengenalpasti taburan hidrokarbon alifatik dan polisiklik aromatik di dalam Asap Tembakau Sekitaran (ATS). ATS adalah asap yang hadir di dalam udara sekitaran berikutan wujudnya aktiviti merokok. Jenis rokok (C1R1 dan C6R1) telah dipilih berdasarkan daripada jawapan soalselidik yang dijalankan bagi menentukan jenis jenama rokok pilihan pengguna. Bagi menganalisa ATS ini, sukarelawan diminta untuk merokok setiap jenis jenama rokok yang dipilih, di dalam bilik yang tertutup. ATS kemudiannya dikumpul menggunakan alat Persampelan Udara Berisipadu Tinggi yang dimuatkan dengan penapis gentian kaca. Sampel asap daripada penapis gentian kaca in kemudiannya diekstrak menggunakan teknik goncangan Ultrasonikasi dan dipisahkan kepada kumpulan alifatik dan aromatik dengan menggunakan turus silika-alumina. Pencirian dan kuantifikasi telah dilakukan menggunakan kromatografi gas dengan pengesan pengionan nyalaan. Keputusan menunjukkan kehadiran unsur n-alkana di dalam ATS yang berada dalam lingkungan C 13 hingga C 36 dan didominasi oleh nombor karbon ganjil berbanding genap. Nilai Indeks Pemilihan Karbon (IPK) berada dalam julat 3.34 hingga 4.90. Kepekatan Jumlah Hidrokarbon Alifatik Terpisah Dikenalpasti (JHAPK) yang wujud dalam ATS berada dalam lingkungan 590 µg m-3 hingga 591µg m-3 dengan peratus lilin tumbuhan dalam julat 61% hingga 64%. Bagi pembahagian sumber, IPK > 1 dan peratus lilin tumbuhan yang tinggi sering dikaitkan dengan sumbangan oleh sumber tumbuhan daratan. Justeru, keputusan ini menunjukkan bahawa tanda pencirian bagi sumber n-alkana masih terpelihara walaupun selepas proses rawatan dan hisapan rokok tembakau. Kadar kepekatan hidrokarbon polisiklik aromatik (HPA) yang dikesan dalam sampel ATS berada dalam julat 11.7 ng m-3 hingga 56.1 ng m-3. Keputusan juga menunjukkan kehadiran berat molekul sederhana hingga besar di mana benzo[g,h,i]perylene merupakan komponen utama yang wujud dalam setiap sampel. Keputusan ini menyokong pendapat bahawa proses merokok melibatkan pembakaran bersuhu tinggi dengan kewujudan zon kurang oksigen di dalam rokok itu sendiri. Walaupun kepekatannya adalah rendah, HPA yang karsinogenik dan mutagenik ini masih hadir di dalam ATS. Ini menjadikan perokok pasif masih berpotensi kepada penyakit-penyakit akibat terdedah kepada HPA.

Hidrolisis klorpirifos (O,O-diethyl-O-3,5,6-trichloro-2-pyridyl phosphorothionate) telah dikaji d... more Hidrolisis klorpirifos (O,O-diethyl-O-3,5,6-trichloro-2-pyridyl phosphorothionate) telah dikaji dalam media akues pada suhu dan keadaan pH yang berbeza. Pemalar kadar dan jangka hayat separa yang diperolehi menunjukkan bahawa klorpirifos lebih stabil dalam keadaan berasid. Kadar degradasi meningkat apabila nilai pH bertambah. Suhu juga mempengaruhi kadar hidrolisis. Hidrolisis klorpirifos dalam air mematuhi tindak balas tertib pertama. Jangka hayat separa klorpirifos dalam larutan akues adalah pendek (di antara 4.57 hingga 14.0 hari), dan ianya bergantung pada kepekatan asal klorpirifos dan jenis larutan akues. Kadar degradasi adalah perlahan dalam larutan 0.02M CaCl 2 dengan kepekatan asal klorpirifos yang tinggi. Perbandingan antara kadar hidrolisis dalam laruatan air steril dan tidak steril tidak menunjukkan peranan biodegradasi yang ketara dalam air tidak disteril. Keputusan ini menunjukkan bahawa parameter pH sahaja tidak mencukupi untuk menjangkakan kadar hidrolisis klorpirifos.

Environmental Science and Pollution Research, Oct 11, 2021

Surface sediments along the Southern Terengganu coast (≤7 km from the coast) were analyzed for po... more Surface sediments along the Southern Terengganu coast (≤7 km from the coast) were analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of 16 USEPA priority polycyclic aromatic hydrocarbons (ΣPAH16) ranged from 2.59 to 155 ng g−1 and their respective alkylated ranged between 8.80 and 24.90 ng g−1. Traces of acephenanthrylene, benzo[c]phenanthrene, thiophenic PAH, and benzonaphthofuran were identified. PAH diagnostic ratios and cross-plots revealed that these sedimentary PAH compounds are derived mainly from pyrogenic sources, primarily from biomass burning and petroleum combustion residues with minor petrogenic input. The high correlations between pyrogenic PAHs to total PAHs (r >0.73, p <0.5), and the Bap/Bep ratio to total PAHs (r = 0.88, p <0.5), suggest that atmospheric deposition and urban runoff are the main deposition pathways. The concentrations of the PAHs in the southern South China Sea fall in the moderate contamination range of 100–1000 ng g−1.

This study was carried out to determine the concentration and distribution of polycyclic aromatic... more This study was carried out to determine the concentration and distribution of polycyclic aromatic hydrocarbons (PAHs) in soils of Kota Bharu, Kelantan Darul Naim. A total of 20 sampling sites were chosen covering the town center and surrounding suburban area of this district. PAHs in soil matrix were extracted using ultrasonic agitation technique with dichloromethane as extraction solvent. Fractionation of PAHs were done using silica-alumina column and the characterization of these individual components were carried out using GCMS. Priority PAHs (PAH 16 as defined by the U.S. Environmental Protection Agency) were predominantly represented by four to six ring compounds with concentration ranging between 0.022 µgg-1 to 24.06 µgg-1. Based on ratios of selected molecular markers, it can be concluded that PAHs in soil were generally derived from combustion sources. A strong correlation between benzo (g,h,i)perylene with total identified PAHs strongly suggest that vehicular emission is the major constituent of this combustion sources.

Sains Malaysiana, Sep 30, 2017

This study investigates the spatial variation of water quality parameters in Sungai Setiu Basin a... more This study investigates the spatial variation of water quality parameters in Sungai Setiu Basin at ten different locations from March 2010 to February 2011. The water quality was assessed using the Water Quality Index by Malaysian Department of Environment (DOE-WQI) and classified according to the Malaysia Interim National Water Quality Standard (INWQS). Six water quality parameters embedded in the DOE-WQI were dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), pH, ammoniacal nitrogen (AN) and total suspended solid (TSS). In addition, this study also examined the changes in water quality over the past 10 years by comparing the present water quality to the previous works. The overall mean WQI value obtained was 84.0 which indicate that the Sungai Setiu basin is in clean condition and all measured water quality parameters gave value within the permissible limits of the INWQS classification except for pH which fall in Class III. It can be concluded that water quality in Sungai Setiu does not varies greatly over a decade. Hence continuous monitoring is needed to improve the water quality and minimize water pollution.

Sains Malaysiana, Jul 1, 2015

Seasonal variations of dissolved and suspended particulate metals were observed. The results were... more Seasonal variations of dissolved and suspended particulate metals were observed. The results were compared with selected Malaysian national rivers, world average and established guidelines. In addition, the enrichment of suspended particulate metals and the partitioning of metals between dissolved and suspended particulate phases were discussed.

Sains Malaysiana, Sep 30, 2021

Sediment cores from the southern South China Sea off the Terengganu coast were analyzed for polyc... more Sediment cores from the southern South China Sea off the Terengganu coast were analyzed for polycyclic aromatic hydrocarbons (PAHs) and perylene. The concentrations of total 17 PAH (TPAHs) and perylene varied between 5.45-27.7 ng/g and 0.51-7.77 ng/g, respectively. Analyses of variance showed significant differences between the stations, but not in sub-bottom depths at the 0.05 level. The PAH cross plots showed a predominance of pyrogenic over petrogenic PAHs. Principal component analysis (PCA) showed clustered PAHs that are correlated with total organic carbon (TOC), indicating the importance of surface runoff via fluvial transport for contributing these PAHs to the coastal environment of the study area. Overall, the concentrations of PAHs in the study area are considered to be in the low range, not exceeding the 100 ng/g mark.

Sains Malaysiana, Jul 1, 2015

Three short sediment cores (12-32 cm) from South China Sea off Southern Terengganu were collected... more Three short sediment cores (12-32 cm) from South China Sea off Southern Terengganu were collected during May (post-Northeast monsoon) and September (pre-Northeast monsoon) 2007. The concentration of total organic carbon (TOC) obtained ranged from 0.41-2.23 and 0.38-2.31% during post and pre-monsoon, respectively. TOC concentration was found to decrease with depth and distance from the coast and river mouth. In particular, station with close proximity to the coast exhibits most pronounced variation of TOC with depth. Besides spatial variation, it is noted that the seasonal variations also considerably affect the distribution and concentrations of TOC, where both near and offshore sampling stations showed significant variations in TOC content during May and September sampling. These findings suggest the importance of terrestrial organic carbon flux, physical mixing and seasonal variations in regulating the concentration and distribution of the organic carbon in the study area.

Penjerapan insektisid klorpirifos (rumusan kormersil berjenama Kensban®, 20% bahan aktif) pada ti... more Penjerapan insektisid klorpirifos (rumusan kormersil berjenama Kensban®, 20% bahan aktif) pada tiga jenis siri tanah (0-25cm) dari kebun sayur-sayuran di negeri Terengganu, Malaysia telah dikaji menggunakan kaedah penjerapan kelompok. Analisis insektisid dijalankan menggunakan kaedah kromatografi gas dilengkapkan dengan pengesan nitrogen and fosforus. Keputusan menunjukkan bahawa tanah yang mengandungi lebih banyak jirim organik dan lempung mempunyai keupayaan menjerap insektisid yang lebih kuat. Selain itu, pH tanah juga mempengaruhi keupayaan penjerapan insektisid di mana penjerapan adalah lebih tinggi pada tanah yang mempunyai nilai pH yang rendah. Secara keseluruhannya, kandungan jirim organik , kandungan lempung dan pH memainkan peranan yang penting dalam penjerapan insektisid klorpirifos. Walau bagaimanapun, tidak boleh dinafikan bahawa keupayaan penjerapan yang diperolehi dalam kajian ini mungkin juga dipengaruhi oleh interaksi di antara klorpirifos, pelarut, pengemulsi, air dengan tapak penjerapan tanah memandangkan klorpirifos yang digunakan adalah formulasi komersil.

A study has been carried out to determine the concentration and distribution of polycyclic aromat... more A study has been carried out to determine the concentration and distribution of polycyclic aromatic hydrocarbons (PAHs) in urban soils of Kemaman, Terengganu. Surface soil samples (< 500 µm) were ultrasonicated using dichloromethane as solvent and the extracts fractionated on silica-alumina column. Detection and quantification of 16 priority PAHs compounds were carried out using GC-FID. With the exception of two stations, results generally indicated that the sum of 16 priority PAHs concentration (total PAHs) in soils ranged from to 6.3 to 176 µg/kg (dry weight); the two stations which exhibited significantly higher levels of total PAHs was at the main road junction located at the heart of the commercial centre of the town (535 µg/kg) and at an industrial estate, adjacent to a sawmill (547 µg/kg). Statistical analysis suggests that there is a significant difference in total PAHs concentration (p<0.05) with sampling sites. Most common PAHs compound observed in almost all the soil samples was BgP indicating the importance of vehicular emission as a source of PAHs in these soils. In addition, contribution of biomass burning to the presence of PAHs in these soils was also observed as indicated by a positive correlation between Benzo[a]pyrene with total PAHs.

PM 2.5 mass concentration and associated water-soluble ionic species in a suburban coastal area o... more PM 2.5 mass concentration and associated water-soluble ionic species in a suburban coastal area of Kuala Terengganu, Malaysia were investigated intermittently from year 2006 to 2009. A total of 78 weekly PM 2.5 samples were analyzed. The mass concentration of PM 2.5 exhibited annual, seasonal and diurnal variations. Temporal distributions of rainfall, sporadic haze episodes and local air flow (sea breeze circulation) were factors controlling PM 2.5 mass variations in the study area. Although the PM 2.5 concentrations were increased during haze episodes in 2006 (August and October) and 2007 (October), their concentrations however, were still within the international guidelines. The average concentration of individual ions was in decreasing trend; SO 4 2-> NH 4

Sains Malaysiana, Jun 30, 2017

The aim of this study was to assess spatial and seasonal variations of dissolved and particulate ... more The aim of this study was to assess spatial and seasonal variations of dissolved and particulate organic carbon (DOC and POC, respectively) in the Setiu Wetland, which is located in the southern region of the South China Sea coastal area. Surface water samples were collected monthly from October 2009-September 2010. In addition, the concentration of chlorophyll-a was determined. The DOC and POC mean concentration varied between 80-340 µM and 60-115 µM, respectively. The results showed that the concentrations of these parameters were mainly influenced by human activities and season. Higher concentrations of DOC (150-340 µM) and POC (75-115 µM) were found at stations near the populated area, aquaculture and palm oil plantation. In addition, higher concentrations of DOC (200-275 µM) and POC (105-150 µM) were also recorded during the monsoon season due to runoff from terrestrial sources and resuspension from bottom sediments. No significant correlation between the low molecular weight (LMW) fractions of DOC and chlorophyll-a (R 2 =0.0096, p>0.05) further supports the hypothesis that phytoplankton not playing key role in regulating the organic carbon distribution. Higher percentage of LMW DOC in monsoon season suggesting possible input of this fraction from land runoff to the wetland area.

Bulletin of Environmental Contamination and Toxicology, Jan 17, 2014

A short-term investigation on the chemical composition of rainwater was carried out at five selec... more A short-term investigation on the chemical composition of rainwater was carried out at five selected sampling stations in Kuantan district, Pahang, Malaysia. Sampling of rainwater was conducted by event basis between September and November 2011. Rainwater samples were collected using polyethylene containers and the parameters measured were cations (sodium, potassium, ammonium, calcium and magnesium) and anions (chlorides, nitrates and sulphates). The average pH value for rainwater samples was 6.0 ± 0.57 in which most of the sampling sites exhibited pH values [5.6. Calcium and sulphate were the most abundant cation and anion, respectively, whilst the concentrations of other major ions varied according to sampling location.

Sains Malaysiana, 2018

A study was carried out to determine the distribution and behaviour of nitrogen (N) compounds (ni... more A study was carried out to determine the distribution and behaviour of nitrogen (N) compounds (nitrite, nitrate, ammonia, dissolved and particulate organic nitrogen) in Sungai Terengganu estuary (TRE). Surface water samples were collected during ebb neap and spring tides for the longitudinal survey along the salinity gradient. The results indicated that all N compounds behave non-conservatively with addition during both tidal cycles, except for nitrate which exhibited removal behaviour during spring tide. In general, higher concentration of N compounds was observed during spring tide compared to neap tide. It is suggested that during spring tide, stronger water turbulence resulted in resuspension of nutrients in bottom sediment and lead to the increase in N compounds concentrations in the surface water. The diurnal survey for the freshwater station showed that the concentrations of N compounds follow the ebb and flood variations, whereas for the coastal station the reverse trend was observed. Comparisons with a previous study under similar tidal conditions show there was an increase in nitrite and ammonia concentrations in TRE, which was probably due to increase in discharge from the rapid development activities around this area. In addition, the presence of a breakwater at the lower part of the estuary may also contribute to the high nutrient content in the estuary due to restricted outflow of nutrients to the coastal area. Overall, the results from this study highlighted the importance of monitoring the N compounds for future protection of the estuary.

PLOS ONE, 2021

The reconstruction of fire history is essential to understand the palaeoclimate and human history... more The reconstruction of fire history is essential to understand the palaeoclimate and human history. Polycyclic aromatic hydrocarbons (PAHs) have been extensively used as a fire marker. In this work, the distribution of PAHs in Borneo peat archives was investigated to understand how PAHs reflect the palaeo-fire activity. In total, 52 peat samples were analysed from a Borneo peat core for the PAH analysis. Pyrogenic PAHs consist of 2–7 aromatic rings, some of which have methyl and ethyl groups. The results reveal that the concentration of pyrogenic PAHs fluctuated with the core depth. Compared to low-molecular-weight (LMW) PAHs, the high-molecular-weight (HMW) PAHs had a more similar depth variation to the charcoal abundance. This finding also suggests that the HMW PAHs were mainly formed at a local fire near the study area, while the LMW PAHs could be transported from remote locations.

Oriental Journal Of Chemistry, 2021

Aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were studied in two sediment c... more Aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were studied in two sediment cores of southern South China Sea off Johor coastal area. The concentrations of the total identified resolved aliphatic hydrocarbons (TiRAHs) in the coastal station (STC104) ranged from 0.35 to 2.07 µg/g while the offshore station (STC100) varied from 0.05 to 14.7 µg/g. The concentrations of total PAHs were varied from not detected to 33.9 ng/g. The nalkanes distribution in STC104 were predominant in short chain carbons from marine productivity, petroleum mixture and minor higher plant input, while STC100 exhibited a bimodal distribution with mixed input of marine and terrestrial origin. PAHs isomer ratios cross-plot have showed mixed input of pyrogenic and petrogenic inputs while perylene was dominated in STC100 followed by fossil fuels and pyrogenic source. Presence of perylene in both cores suggesting the contribution of biogenic sources. Principal component analysis was used to cluste...

Marine Pollution Bulletin, 2020

Sains Malaysiana, 2018

A seasonal study of phosphorus (P)-based nutrients was carried out in Sungai Setiu basin which is... more A seasonal study of phosphorus (P)-based nutrients was carried out in Sungai Setiu basin which is located in the southern region of the South China Sea (Malaysia) from July 2010 until June 2011. Parameters measured were dissolved inorganic P (DIP), dissolved organic P (DOP) and total particulate P (TPP). In addition, DOP concentration was size fractionated into high molecular weight (HMW, 0.7 µm-100 kDa), middle MW (MMW, 100-30 kDa) and low MW (LMW, <30 kDa). The results show that the mean concentration of P-based nutrients ranged between 3.2-7.0 µg/L P for DIP, 5.6-12.1 µg/L P for DOP and 9.2-119.4 µg/L P for TPP. Higher mean concentrations of P were recorded at urban and agricultural areas. In addition, the distribution of P was affected by season as higher mean concentrations of P were observed during the northeast monsoon due to the surface runoff of nutrients during this heavy raining season. The fractionation study of DOP further revealed that HMW fraction was abundant in Sungai Setiu, making up approximately 60% of the total DOP. This high percentage of HMW DOP was recorded at stations in the vicinity of agriculture area and towns suggesting an important contribution from anthropogenic activities. The LMW DOP fraction was not significantly associated with chlorophyll-a, suggesting that the phytoplankton might not be the predominant contributor for LMW fraction in this river. We suggest that these organic nutrient inputs should be monitored as part of the management of the aquatic system.

Chemosphere, 2019

This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) ... more This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) and assess the risk to health at different sites in Malaysia. Continuous monitoring of

Chemosphere, 2018

Distribution, sources and potential health risks of polycyclic aromatic hydrocarbons (PAHs) in PM... more Distribution, sources and potential health risks of polycyclic aromatic hydrocarbons (PAHs) in PM 2.5 collected during different monsoon seasons and haze episode in Kuala Lumpur, Chemosphere,