Nurul Bahiyah Abd Wahid

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.

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.

Distribution of surfactants along the estuarine area of Selangor River, Malaysia

This study aims to determine the levels of methylene blue active substances (MBAS) and ethyl violet active substances (EVAS) as anionic surfactants and of disulphine blue active substances (DBAS) as cationic surfactants in the surface microlayer (SML) around an estuarine area using colorimetric methods. The results show that the concentrations of surfactants around the estuarine area were dominated by anionic surfactants (MBAS and EVAS) with average concentrations of 0.39 and 0.51 μmol L⁻¹, respectively. There were significant between-station differences in surfactant concentrations (p<0.05) with higher concentrations found at the stations near the sea. The concentration of surfactants was higher during the rainy season than the dry season due to the influence of runoff water. Further investigation using total organic carbon (TOC) and total organic nitrogen (TON) shows that there is a significant correlation (p<0.05) between both anionic and cationic surfactants and the TON concentration.

Source Apportionment of Particulate Matter (PM10) and Indoor Dust in a University Building

A study on source apportionment of indoor dust and particulate matter (PM10) composition was conducted in a university building by using chemometrics. The objective of this study was to investigate the potential sources of selected heavy metals and ionic species in PM10 and indoor dust. PM10 samples were collected using a low-volume sampler (LVS) and indoor dust was collected using a soft brush. Inductively coupled plasma spectrometry (ICP-MS) was used to determine the concentration of heavy metals, while the concentration of cations and anions was determined by atomic absorption spectrometer (AAS) and ion chromatography (IC), respectively. The concentration of PM10 recorded in the building throughout the sampling period ranged from 20 ± 10 μgm−3 to 80 ± 33 μgm−3. The composition of heavy metals in PM10 and indoor dust were dominated by zinc (Zn), followed by lead (Pb), copper (Cu), and cadmium (Cd). Principle component analysis (PCA) and multiple linear regression (MLR) showed that the main sources of pollutants in PM10 came from indoor renovations (73.83%), vehicle emissions (16.38%), earth crust sources (9.68%), and other outdoor sources (0.11%). For indoor dust, the pollutant source was mainly earth crust. This study suggests that chemometrics can be used for forensic investigation to determine the possible sources of indoor contaminants within a public building.

Correlation Between Surfactants and Heavy Metals in a Natural Lake

There is some concern that when heavy metals and surfactants exist together in the environment, the surfactants will affect the transport and fate of the heavy metals. This study was conducted to determine the presence of surfactants and heavy metals in a natural lakes surface microlayer and in rainwater from seven locations in the Lake Chini area in Malaysia. Colorimetric analysis was used to determine the concentration of anionic surfactants as methylene blue active substances (MBAS) and cationic surfactants as disulphine blue active substances (DBAS). Inductively coupled plasma mass spectrometry was used to determine the concentration of heavy metals such as Cu, Pb, Zn, Fe, Cd, and Ni. The results indicated that the average concentrations of MBAS and DBAS in the lakes surface microlayer were higher in the dry season (0.27 ± 0.06 and 0.22 ± 0.02 μmol L−1) than in the wet season (0.22 ± 0.03 and 0.19 ± 0.02 μmol L−1). The average concentrations of MBAS and DBAS in rainwater were 0.21 ± 0.02 μmol L−1 and 0.18 ± 0.02 μmol L−1, respectively. Surfactants in the lakes surface microlayer were found to be positively correlated with Pb, Cd, Zn (p < 0.01) and with Ni (p < 0.05). These findings have implications when evaluating fate & transport of metals in the presence of surfactants that could be useful in environmental forensic investigations.

Monsoonal variations in atmospheric surfactants at different coastal areas of the Malaysian Peninsula

This study determined the effect of monsoonal changes on the composition of atmospheric surfactants in coastal areas. The composition of anions (SO4(2-), NO3(-), Cl(-), F(-)) and the major elements (Ca, K, Mg, Na) in aerosols were used to determine the possible sources of surfactants. Surfactant compositions were determined using a colorimetric method as methylene blue active substances (MBAS) and disulphine blue active substances (DBAS). The anion and major element compositions of the aerosol samples were determined by ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results indicated that the concentrations of surfactant in aerosols were dominated by MBAS (34-326pmolm(-3)). Monsoonal changes were found to significantly affect the concentration of surfactants. Using principal component analysis-multiple linear regressions (PCA-MLR), major possible sources for surfactants in the aerosols were motor vehicle emissions, secondary aerosol and the combustion of biomass along with marine aerosol.

Composition of Surfactants from Sea-Surface Microlayer and Marine Aerosols along the Malacca Straits

This study aims to determine the concentrations of surfactants on the sea-surface microlayer and in atmospheric aerosols from several coastal areas along the Malacca Straits. The concentrations of surfactants from the sea-surface microlayer (collected using rotation drum) and aerosols (collected using HVS) were analysed as Methylene Blue Active Substances (MBAS) and Disulphine Blue Active Substances (DBAS) by colorimetric method using a UV–visible spectrophotometer. The results of this study show the average concentrations of surfactants in the sea-surface microlayer ranged between undetected and 0.36 ± 0.34 μmolL−1 for MBAS and between 0.11 ± 0.02 and 0.21 ± 0.13 μmolL−1 for DBAS. The contribution of surfactants from the sea-surface microlayer to the composition of surfactants in atmospheric aerosols appears to be more dominant in coarse mode aerosols. Other anthropogenic sources such as regional biomass burning can also contribute to the amount of atmospheric surfactants as MBAS.