Annual Concentration Report and Emission Sources Analysis of the Air Pollutants Measured by the Air Quality Monitoring Station

Abstract

Problem statement: Air Quality Monitoring (AQM) station at Kasetsart University, Si Racha Campus, Thailand, was routinely monitor the annual concentrations and analysis the emission sources of the air pollutants in the area since 2007. The level of concentration CO, SO₂, NO_x and O₃ were measured. PM₁₀ concentration was measured by mean of TOEM method. The PM₁₀ and TSP (manifold) filters were collected for the measurement of heavy metals adsorbed in the particulate by ICP-AES techniques. Scanning Electron Microscopic (SEM) and Energy Dispersive Spectrometric (EDS) techniques were used to identify the morphologies and elemental compositions of particulate matters from the PM₁₀ and TSP filters. Approach: The annual concentrations of all pollutants were almost real-time reported from July 2007-2008. The O₃ concentrations are higher than the standard level (100 ppb) in July 2007 and April 2008 with the value of 109 and 114 ppb, respectively. Average PM₁₀ concentrations are higher than the standard level (120 μg.m^-3) in November 2007, January 2008 and March 2008 with the value of129, 123 and 125 μg.m^-3, respectively. Strong correlations between NO₂ with O₃ and between NO₂ with PM₁₀were found. Results: These results showed that NO₂ was the precursor of the photochemical reaction and generate O₃. NO₂concentrations are found to be corresponding with both O₃ and PM₁₀. The directions of O₃ emission sources were the southwest, south and southeast due to wind direction, whereas the PM₁₀ are originated from the northwest. The microscopic structures of TSP provided various shapes and dimensions from 0.1 to greater than 100 μm, while the microstructures of PM₁₀ presented the needle-like and spherical shape. SEMEDS analysis was able to detect some element (C, O, F, Na, Al, Si and K), while the ICP-AES showed that there were other heavy metals present in the filter sample (Ni, Cu, Zn, Pb and Se). Conclusion: Among the amounts of selected heavy metals, Zn is the most probable among all metals with the value of 1.3891±1.6198 μg .g^-1.m^-3 in TSP. Amounts of heavy metals inPM₁₀, Cu is dominated with 0.5374±0.8084 μg .g^-1.m^-3, the others were almost in the same levels and much lower than in TSP. Correlation coefficient between each metal can be estimate the emission source of their particulate matter together with the wind speed and wind direction.