Mohd Talib Latif

Trend and status of air quality at three different monitoring stations in the Klang Valley, Malaysia

Over the last decades, the development of the Klang Valley (Malaysia), as an urban commercial and industrial area, has elevated the risk of atmospheric pollutions. There are several significant sources of air pollutants which vary depending on the background of the location they originate from. The aim of this study is to determine the trend and status of air quality and their correlation with the meteorological factors at different air quality monitoring stations in the Klang Valley. The data of five major air pollutants (PM10, CO, SO2, O3, NO2) were recorded at the Alam Sekitar Sdn Bhd (ASMA) monitoring stations in the Klang Valley, namely Petaling Jaya (S1), Shah Alam (S2) and Gombak (S3). The data from these three stations were compared with the data recorded at Jerantut, Pahang (B), a background station established by the Malaysian Department of Environment. Results show that the concentrations of CO, NO2 and SO2 are higher at Petaling Jaya (S1) which is due to influence of heavy traffic. The concentrations of PM10 and O3, however, are predominantly related to regional tropical factors, such as the influence of biomass burning and of ultra violet radiation from sunlight. They can, though, also be influenced by local sources. There are relatively stronger inter-pollutant correlations at the stations of Gombak and Shah Alam, and the results also suggest that heavy traffic flow induces high concentrations of PM10, CO, NO2 and SO2 at the three sampling stations. Additionally, meteorological factors, particularly the ambient temperature and wind speed, may influence the concentration of PM10 in the atmosphere.

Surfactants in the sea-surface microlayer and their contribution to atmospheric aerosols around coastal areas of the Malaysian peninsula.

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.

Composition and source apportionment of surfactants in atmospheric aerosols of urban and semi-urban areas in Malaysia.

This study was conducted to determine the composition and source apportionment of surfactant in atmospheric aerosols around urban and semi-urban areas in Malaysia based on ionic compositions. Colorimetric analysis was undertaken to determine the concentrations of anionic surfactants as Methylene Blue Active Substances (MBAS) and cationic surfactants as Disulphine Blue Active Substances (DBAS) using a UV spectrophotometer. Ionic compositions were determined using ion chromatography for cations (Na(+), NH4(+), K(+), Mg(2+), Ca(2+)) and anions (F(-), Cl(-), NO3(-), SO4(2-)). Principle component analysis (PCA) combined with multiple linear regression (MLR) were used to identify the source apportionment of MBAS and DBAS. Results indicated that the concentrations of surfactants at both sampling sites were dominated by MBAS rather than DBAS especially in fine mode aerosols during the southwest monsoon. Three main sources of surfactants were identified from PCA-MLR analysis for MBAS in fine mode samples particularly in Kuala Lumpur, dominated by motor vehicles, followed by soil/road dust and sea spray. Besides, for MBAS in coarse mode, biomass burning/sea spray were the dominant source followed by motor vehicles/road dust and building material.

Long term assessment of air quality from a background station on the Malaysian Peninsula

Rural background stations provide insight into seasonal variations in pollutant concentrations and allow for comparisons to be made with stations closer to anthropogenic emissions. In Malaysia, the designated background station is located in Jerantut, Pahang. A fifteen-year data set focusing on ten major air pollutants and four meteorological variables from this station were analysed. Diurnal, monthly and yearly pollutant concentrations were derived from hourly continuous monitoring data. Statistical methods employed included principal component regression (PCR) and sensitivity analysis. Although only one of the yearly concentrations of the pollutants studied exceeded national and World Health Organisation (WHO) guideline standards, namely PM10, seven of the pollutants (NO, NO2, NOx, O3, PM10, THC and CH4) showed a positive upward trend over the 15-year period. High concentrations of PM10 were recorded during severe haze episodes in this region. Whilst, monthly concentrations of most air pollutants, such as: PM10, O3, NOx, NO2, CO and NmHC were recorded at higher concentrations between June and September, during the southwest monsoon. Such results correspond with the mid-range transport of pollutants from more urbanised and industrial areas. Diurnal patterns, rationed between major air pollutants and sensitivity analysis, indicate the influence of local traffic emissions on air quality at the Jerantut background station. Although the pollutant concentrations have not shown a rapid increase, an alternative background station will need to be assigned within the next decade if development projects in the surrounding area are not halted.

Surfactants in South East Asian Aerosols

Environmental Context.Surfactants are present in all atmospheric aerosols with potential effects on surface tension, cloud droplets and even human health. They appear to be anionic and associated with yellow aqueous extracts, suggesting a humic-like character. These surfactants are probably derived from the oxidation of combustion-generated soot (from vehicles and forest fires). Abstract.The concentration of surfactants in aerosols was determined at several sites in South East Asia, Bangi, Penang and Kota Kinabalu in Malaysia and Bangkok, Thailand, as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS) for anionic surfactants and disulphine blue active substances (DBAS) for cationic surfactants. The methodology used is based on the formation of extractable ion-association complexes of surfactants and dye in organic solvents followed by spectrometric measurement of the intensity of the extracted coloured complex. Results showed surfactants in aerosols are mostly in the anionic form as MBAS and EVAS, and higher in aerosols collected in congested areas, especially in times of forest fires. Concentrations are in the range of 34.6 to 285.0 pmol m−3 for MBAS and 129.9 to 932.2 pmol m−3 for EVAS. Several different types of soot and humic acid seem possible sources of surfactants in atmospheric aerosols. Laboratory experiments suggested that combustion products, especially from motor vehicles, are important primary sources of surfactants in aerosols. There is also some laboratory evidence that there are secondary sources for these surfactants in aerosols, possibly humic-like substances (HULIS) from the oxidation and photochemical reaction of soots and humic acid.

Composition of Household Dust in Semi-urban Areas in Malaysia

A study of household dust composition was conducted in a semi-urban area around Kajang and Bandar Baru Bangi Selangor, Malaysia. Samples of household dust were collected from 31 randomly selected houses using a vacuum cleaner equipped with a changeable dust bag. Parameters analysed were anions (Cl , SO 4 , and NO3 ), cations (K þ, Ca2þ, and Mg2þ), and heavy metals (Cd, Fe, Ni, and Pb) to deduce the possible sources and evaluate the toxicity of indoor dust. The concentration of each parameter was compared to the concentration of street dust collected outside the houses. The results showed that the composition of anions was dominated by Cl followed by SO 4 and NO3-; cations concentration by the sequence of Ca2þ4Kþ4Mg2þ and for heavy metals concentration, Pb was present in the highest concentration followed by Ni 4 Fe 4Cd 4Zn. The study also showed that the concentration of most parameters analyzed were higher in household dust than street dust, suggesting that the composition of household dust is more closely related to indoor activities and theA study of household dust composition was conducted in a semi-urban area around Kajang and Bandar Baru Bangi Selangor, Malaysia. Samples of household dust were collected from 31 randomly selected houses using a vacuum cleaner equipped with a changeable dust bag. Parameters analysed were anions (Cl � , SO 2� 4 , and NO3� ), cations (K þ ,C a 2þ , and Mg 2þ ), and heavy metals (Cd, Fe, Ni, and Pb) to deduce the possible sources and evaluate the toxicity of indoor dust. The concentration of each parameter was compared to the concentration of street dust collected outside the houses. The results showed that the composition

Source apportionment of surfactants in marine aerosols at different locations along the Malacca Straits.

This study aims to determine the source apportionment of surfactants in marine aerosols at two selected stations along the Malacca Straits. The aerosol samples were collected using a high volume sampler equipped with an impactor to separate coarse- and fine-mode aerosols. The concentrations of surfactants, as methylene blue active substance and disulphine blue active substance, were analysed using colorimetric method. Ion chromatography was employed to determine the ionic compositions. Principal component analysis combined with multiple linear regression was used to identify and quantify the sources of atmospheric surfactants. The results showed that the surfactants in tropical coastal environments are actively generated from natural and anthropogenic origins. Sea spray (generated from sea-surface microlayers) was found to be a major contributor to surfactants in both aerosol sizes. Meanwhile, the anthropogenic sources (motor vehicles/biomass burning) were predominant contributors to atmospheric surfactants in fine-mode aerosols.

Spatial and temporal air quality pattern recognition using environmetric techniques: a case study in Malaysia

The objective of this study is to identify spatial and temporal patterns in the air quality at three selected Malaysian air monitoring stations based on an eleven-year database (January 2000-December 2010). Four statistical methods, Discriminant Analysis (DA), Hierarchical Agglomerative Cluster Analysis (HACA), Principal Component Analysis (PCA) and Artificial Neural Networks (ANNs), were selected to analyze the datasets of five air quality parameters, namely: SO2, NO2, O3, CO and particulate matter with a diameter size of below 10 μm (PM10). The three selected air monitoring stations share the characteristic of being located in highly urbanized areas and are surrounded by a number of industries. The DA results show that spatial characterizations allow successful discrimination between the three stations, while HACA shows the temporal pattern from the monthly and yearly factor analysis which correlates with severe haze episodes that have happened in this country at certain periods of time. The PCA results show that the major source of air pollution is mostly due to the combustion of fossil fuel in motor vehicles and industrial activities. The spatial pattern recognition (S-ANN) results show a better prediction performance in discriminating between the regions, with an excellent percentage of correct classification compared to DA. This study presents the necessity and usefulness of environmetric techniques for the interpretation of large datasets aiming to obtain better information about air quality patterns based on spatial and temporal characterizations at the selected air monitoring stations.

Rediscovering Atmospheric Surfactants

In recent decades there has been surprisingly little research on surface-active compounds in the atmosphere. Why should we care, you ask? Are surfactants such a big deal? We know how anthropogenic surfactants in sea spay in some areas led to the death of long-established beach front pines, but is there a broader impact of atmospheric surfactants? Well, indeed there is, and it is the subject of continuing discussion and speculation. In the 1970s, a number of investigators studying organic micropollutants considered the existance of surface-active compounds in the atmosphere. Long-chain carboxylic acids were seen as a likely source of surface activity. There was also a growing interest in the potential of the sea surface microlayer to accumulate organic compounds and complexed metals, and to possibly transport the materials into the atmosphere during bubble bursting.[1,2] Appel et al. found some two thirds of the non-carbonate carbon in aerosols to be surface active.[3] By the early 1980s Seidl and Hanel[4] and Gill et al.[5] had established the presence of surface-active substances in both rainwater and aerosols, but only at some 50 picomoles per cubic metre, or 10% of total aerosol mass.This was so low that there was little chance that these compounds would play an important role in reducing droplet size or altering the rate of transfer of water to and from droplets. Despite this, Winfried Seidl[6] retained an interest in surfactants into the current millennium reasserting the point that soluble surfactants in rainwater behaved as if they were the expected long-chain carboxylic acids, recently identified using TOF-SIMS.[7] The early 21st century has seen a re-emergence of research on atmospheric surfactants along with a great deal of speculation about the potential role they might play. This interest has paralleled a rising number of papers on water-soluble organic materials and the awareness of the ubiquitous presence of humic-like substances (HULIS) in the atmosphere. Thus atmospheric surfactants have recently re-emerged with much of the enthusiasm they found among marine aerosol chemists a quarter-century ago. The current work on atmospheric surfactants now seems far-reaching and imaginative. Dobson et al.[8] have championed a role for such compounds in the origin of life. They propose an inverted micelle model for aerosol structure where the surfactants coat the aqueous core. The surfaceactive organic compounds have their hydrocarbon tails facing into the atmosphere and more polar ends in the water. In this way organic materials that accumulated at the surface of an early ocean would, once ejected as aerosols, have the high concentrations of materials necessary for the origin of life. Evidence of this process would have long been lost, but not the excitement such speculation has brought in allowing aerosol science to interact with exobiology. An equally broad vision comes from Cristina Facchini and her colleagues, who conceived that surface activity may play a role in controlling global climate. It had long been clear that surface tension was an important control on droplet size and aerosol activation,[9] but the re-interest in surfactants reminds us that the small changes in droplet populations they induce could alter cloud albedo and as well as the formation of precipitation;[10,11] yet another mechanism for natural and anthropogenic climate forcing. The sea surface microlayer is once again of interest. Caterina Oppo has, for some years, been studying the potential of the ocean surface to redistribute trace substances, through bubble bursting. This could be important in the mobilization of micropollutants at a global level. In an era where it is no longer generally believed that metals are strongly bound within the sea surface microlayer, attention has turned more towards the organic materials here as a mode of transfer to the atmosphere. Thus we have seen studies of the accumulation of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and tributyltin at the sea surface.[12] Surfactants can certainly solubilize materials, so they might also increase the bioavailability, especially that of relatively non-polar compounds. However atmospheric scientists are not always aware of the relevance of lipids as surfactants in biological systems. The pulmonary surfactant that coats the human lung is much affected by air pollutants. Ozone and trace metals can oxidize this material, reducing gas exchange.[13] Although particles are known to interact with pulmonary surfactants,[14] the effect of

Surfactants in the sea-surface microlayer and atmospheric aerosol around the southern region of Peninsular Malaysia.

This study was conducted to determine the composition of surfactants in the sea-surface microlayer (SML) and atmospheric aerosol around the southern region of the Peninsular Malaysia. Surfactants in samples taken from the SML and atmospheric aerosol were determined using a colorimetric method, as either methylene blue active substances (MBAS) or disulphine blue active substances (DBAS). Principal component analysis with multiple linear regressions (PCA-MLR), using the anion and major element composition of the aerosol samples, was used to determine possible sources of surfactants in atmospheric aerosol. The results showed that the concentrations of surfactants in the SML and atmospheric aerosol were dominated by anionic surfactants and that surfactants in aerosol were not directly correlated (p>0.05) with surfactants in the SML. Further PCA-MLR from anion and major element concentrations showed that combustion of fossil fuel and sea spray were the major contributors to surfactants in aerosol in the study area.