Characteristics of airborne Pm2.5 and Pm2.5-10 in the urban environment of Kuala Lumpur

Gravimetric and elemental analyses were conducted at a site in Kuala Lumpur from 2008 to 2010, representing the local air quality of urban and traffic. Eighteen elements were detected by ED-XRF and was further analysed for enrichment factor and correlation study. About 19.7% elements were identified and detected in PM10, including 8.2% and 11.5% in fine and coarse fractions, respectively. Al was found predominant in coarse fraction. However its composition in PM2.5 was highly enriched pointed to some anthropogenic emission source. In fine particulates, the total mass was mostly dominated by Al, K, Mg and S. Those elements, probably from biomass burning accounted for more than 90% of total elemental detected in PM2.5

The Effects of Bottom Ash from MSWI Used as Mineral Additions in Concrete

Municipal solid waste incinerators (MSWI) produce by products which can be classified as bottom and fly ashes. The bottom ash accounts for 85–90 % of the solid product resulting from MSW combustion. The aimed of the present work is to study the effect of replacing partial of bottom ash were manufactured. Fresh and hardened properties of the concrete were compared in order to study the suitable cement-bottom ash replacement. Bottom ash was found to have some reactivity, but without greatly affecting the hydration process of OPC at 10 % replacement. However at more than 10 % replacement, the addition of bottom ash greatly affected strength

Estimation Of Missing Values In Air Pollution Dataset By Using Various Imputation Methods

The aim of this study is to determine the best imputation method to fill in the various gaps of missing values in air pollution dataset. Ten imputation methods such as Series Mean, Linear Interpolation, Mean Nearest Neighbour, Expectation Maximization, Markov Chain Monte Carlo, 12-hours Moving Average, 24-hours Moving Average, and Exponential Smoothing (α = 0.2, 0.5, and 0.8) were applied to fill in the missing values. Annual hourly monitoring data for ambient temperature, wind speed, humidity, SO2, NO2, O3, CO, and PM10 from Petaling Jaya and Shah Alam were used from 2012 to 2016. These datasets were simulated into three types of missing data patterns that vary in length gaps of missing patterns, i.e. simple, medium and complex patterns. Each patterns was simulated into two percentages of missing, i.e. 10% and 20%. The performance of these imputation methods was evaluated using four performance indicator: mean absolute error, root mean squared error, prediction accuracy, and index of agreement. Overall, the Expectation Maximization method was selected as the best method of imputation to fill in the simple, medium and complex patterns of simulated missing data, while the Series Mean method was shown as the worst method of imputation

New ray on remediation of high rings polycyclic aromatic hydrocarbons: remediation of raw petroleum sludge using solidification and stabilization method

Solidification/Stabilization (S/S) method with cement as a binder to remediate metals in petroleum sludge has been suc�cessfully proven. However, this technique has not yet been explored to remediate organic contaminants since a high concentra�tion of Total Petroleum Hydrocarbon (TPH) was also detected in the sludge. This study focuses on remediating 16 Polycyclic Aromatic Hydrocarbons (PAHs) compounds in raw petroleum sludge with Portland cement as a binder using the S/S method. The initial concentration of 16 PAHs in the raw sludge was first measured before the performance of the S/S method to remedi�ate the PAHs were evaluated. The S/S matrices were tested for leaching behavior and strength after 7 and 28 days by air cur�ing. The leaching test was measured using the Toxicity Characteristics Leaching Procedure (TCLP), and the remaining PAHs concentration in the matrices was analyzed using a Gas Chromatography-Mass Spectrometer (GC-MS). In the raw sludge, all 16 PAHs compounds were below the standard limit except for Benzo(a)anthracene, Benzo(a)pyrene, Dibenzo(ah)anthracene, and Indeno(1,2,3- cd_ pyrene), which are considered as high rings PAHs. The high rings PAHs show lower concentration in leachate than low rings PAHs, which indicates the potential of the S/S method in remediating high rings PAHs. The high sludge ratio in S/S matrices has shown that the percentage strength is increasing, similar to Portland cement. Therefore, this study contributed to the possibility of the S/S method in the remediation of PAHs in petroleum sludge by using only Portland cement as a binder

Imputation methods for filling missing data in urban air pollution data for Malaysia

The air quality measurement data obtained from the continuous ambient air quality monitoring (CAAQM) station usually contained missing data. The missing observations of the data usually occurred due to machine failure, routine maintenance and human error. In this study, the hourly monitoring data of CO, O3, PM10, SO2, NOx, NO2, ambient temperature and humidity were used to evaluate four imputation methods (Mean Top Bottom, Linear Regression, Multiple Imputation and Nearest Neighbour). The air pollutants observations were simulated into four percentages of simulated missing data i.e. 5%, 10%, 15% and 20%. Performance measures namely the Mean Absolute Error, Root Mean Squared Error, Coefficient of Determination and Index of Agreement were used to describe the goodness of fit of the imputation methods. From the results of the performance measures, Mean Top Bottom method was selected as the most appropriate imputation method for filling in the missing values in air pollutants data

Variations of Ground-level Ozone Concentration in Malaysia: A Case Study in West Coast of Peninsular Malaysia

Hourly ground ozone concentration, measured from the monitoring stations in the West Coast of Peninsular Malaysia for the period of 10 years (2003-2012) were used to analyse the ozone characteristic in Nilai, Melaka and Petaling Jaya. The prediction of tropospheric ozone concentrations is very important due to the negative impacts of ozone on human health, climate and vegetation. The mean concentration of ozone at the studied areas had not exceeded the recommended value of Malaysia Ambient Air Quality Guideline (MAAQG) for 8-hour average (0.06 ppm), however some of the measurements exceeded the hourly permitted concentration by MAAQG that is 0.1 ppm. Higher concentration of ozone can be observed during the daytime since ozone needs sunlight for the photochemical reactions. The diurnal cycle of ozone concentration has a mid-day peak (14:00-15:00) and lower night-time concentrations. The ozone concentration slowly rises after the sun rises (08:00), reaching a maximum during daytime and then decreases until the next morning

Variations of Ground-level Ozone Concentration in Malaysia: A Case Study in West Coast of Peninsular Malaysia

Hourly ground ozone concentration, measured from the monitoring stations in the West Coast of Peninsular Malaysia for the period of 10 years (2003-2012) were used to analyse the ozone characteristic in Nilai, Melaka and Petaling Jaya. The prediction of tropospheric ozone concentrations is very important due to the negative impacts of ozone on human health, climate and vegetation. The mean concentration of ozone at the studied areas had not exceeded the recommended value of Malaysia Ambient Air Quality Guideline (MAAQG) for 8-hour average (0.06 ppm), however some of the measurements exceeded the hourly permitted concentration by MAAQG that is 0.1 ppm. Higher concentration of ozone can be observed during the daytime since ozone needs sunlight for the photochemical reactions. The diurnal cycle of ozone concentration has a mid-day peak (14:00-15:00) and lower night-time concentrations. The ozone concentration slowly rises after the sun rises (08:00), reaching a maximum during daytime and then decreases until the next morning

Temporal Characterisation of Ground-level Ozone Concentration in Klang Valley

In Malaysia, ground-level ozone (O3) is one of the most significant air pollutants due to the increasing sources of ozone precursors. Hence, the surface O3 concentration should have received substantial attention because of its negative effects to human health, vegetation and the environment. In this study, hourly air pollutants dataset (i.e O3, Carbon monoxide (CO), Nitrogen dioxide (NO2), Particulate matter (PM10), Non-methane hydrocarbon (NmHC), Sulphur dioxide (SO2)) and weather parameters (i.e. wind speed (WS), wind direction (WD), temperature (T), ultraviolet B (UVB)) for ten years period (2003-2012) in Klang Valley were selected for analysis in this study. Two monitoring stations were selected that are Petaling Jaya and Shah Alam. The aim of the study is to determine the diurnal variations of O3 concentrations according to the seasonal monsoon and the correlation between the ground-level O3 concentration and others parameter. A high concentration of ground-level O3 was observed during the first transition (April to May) for both of the stations. While at a low surface, O3 concentration was found out during the southwest monsoon within June to September. Pearson correlation was used to find the correlation between the O3 concentration and all other pollutants and weather parameters. Most of the relationship between O3concentrationswas positively correlated with NO2 and negative relationship was found out with NMHC. These results were expected since these pollutants are known as the O3 precursors. Besides that, O3 concentration and its precursors show a positive significant correlation with all meteorological factors except for relative humidity

Temporal Characterisation of Ground-level Ozone Concentration in Klang Valley

In Malaysia, ground-level ozone (O3) is one of the most significant air pollutants due to the increasing sources of ozone precursors. Hence, the surface O3 concentration should have received substantial attention because of its negative effects to human health, vegetation and the environment. In this study, hourly air pollutants dataset (i.e O3, Carbon monoxide (CO), Nitrogen dioxide (NO2), Particulate matter (PM10), Non-methane hydrocarbon (NmHC), Sulphur dioxide (SO2)) and weather parameters (i.e. wind speed (WS), wind direction (WD), temperature (T), ultraviolet B (UVB)) for ten years period (2003-2012) in Klang Valley were selected for analysis in this study. Two monitoring stations were selected that are Petaling Jaya and Shah Alam. The aim of the study is to determine the diurnal variations of O3 concentrations according to the seasonal monsoon and the correlation between the ground-level O3 concentration and others parameter. A high concentration of ground-level O3 was observed during the first transition (April to May) for both of the stations. While at a low surface, O3 concentration was found out during the southwest monsoon within June to September. Pearson correlation was used to find the correlation between the O3 concentration and all other pollutants and weather parameters. Most of the relationship between O3concentrationswas positively correlated with NO2 and negative relationship was found out with NMHC. These results were expected since these pollutants are known as the O3 precursors. Besides that, O3 concentration and its precursors show a positive significant correlation with all meteorological factors except for relative humidity