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Title of Thesis

Nazia Shaheen
Institute/University/Department Details
Department of Chemistry/ Quaid-i-Azam University Islamabad
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
aerosol trace metal burden, tsp size distribution, air quality, air pollution, trace metal

The study reported in this thesis was conceived to determine the current status of ambient air quality in metropolitan Islamabad, Pakistan, towards an accurate assessment of the prevailing air pollution problems facing this and other major cities of the country. The investigation was taken up in terms of trace metal contents of aerosol, TSP and their possible correlations with meteorological conditions influencing their distribution in the ambient atmosphere. Ten metals (Na, K, Fe, Zn, Pb, Mn, Cr, Co, Ni and Cd) were estimated in TSP samples collected on glass fiber filters in urban (n=592) and rural (n=79) atmosphere of Islamabad. The wet digestion method (HNO3/HCIO4) was used for metal analysis by the flame atomic absorption spectrometry (F AAS). High volume air samplers were used at two stations to collect the aerosol particulate samples from June 2001 to May 2003. Regular meteorological data were obtained from National Agriculture Research Council (NARC) on daily basis. Total suspended particulate matter was, on the average, higher in urban atmosphere (156.3 µg/m3 compared with rural atmosphere (141.6 µg/m3) For the urban site, maximum mean contribution was noted for Fe (1.793 µg/m3) followed by Na (1.407 µg/m3) Zn (0.962 µg/m3) K (0.685 µg/m3) and Pb (0.149 µg/m3). Maximum levels for the rural site were noted for Na (1.035 µg/m3) followed by Zn (0.666 µg/m3) K (0.664 µg/m3) and Fe (0.595 µg/m3) Mastersizer was used for TSP size fractionation on % volume basis; these include PM<1.0, PM10-2.5, PM2.5-5.0, PM5.0-10, PM10-15, PM15-25, PM25-50, PM50-100 and PM>100. The PM5.0-10 fraction range was found to be the most abundant fraction (20.36 %) followed by PM10-15 (17.39 %) and PM15-25 (16.17 %) while the fine fractions (PM<1.0) and giant particles (PM>100) showed comparable lower levels at both sites. Statistical linear correlation analysis was conducted to determine the dependence of metals on particle size fractions regarding their distribution in aerosols. Significant correlations were observed for Fe, Zn, Pb, Mn, Co and Cd in rural samples and for Fe, Zn, Pb, Cr, Mn, Ni and Cd in urban samples. Fine particles PM<2.5 exhibited a mutual strong association, while an inverse relationship was observed with larger fractions. The metals showed, in general, significant positive correlation with fine particle fractions but negative with coarse fractions. The metal and particulate size distribution in the aerosols was examined in relation to their dependence on selected meteorological parameters, such as temperature, relative humidity, wind speed, sunshine, rain fall and pan evaporation. No viably strong correlations existed between meteorological parameters and metal levels; however, a significant positive correlation evidenced the temperature dependence of metal and TSP distribution. Particulates up to PM15-25 were found to be strongly correlated with temperature while giant/large particles showed of such temperature dependence. Study of seasonal variation in metal content exhibited high mean concentrations for Fe, Zn Ni and Cd during summer. The particulate fraction PM5.0-10 emerged as dominant fraction during the four seasons. Fine particulates showed higher levels in summer while coarse and giant particles dominated in winter. The correlation study, duly supported by regression analysis, showed positive regression gradients between the levels of Zn-Fe, Zn-Na, Pb-K, Ni-Mn and Co-Cr, while negative gradients emerged for Na-Fe, Cr-Mn and Co-Mn at defined significant, correlation coefficient values. The TSP and metal source identification was carried out by Principal Component Analysis (PCA) and Cluster Analysis (CA). Six sources were identified to this effect: industrial emissions, vehicular emission, electroplating and metallurgical units, biomass burning, natural wind blown dust and fly ash. The data pertaining to the present study were compared with the counterpart data reported for other parts of the world under atmospheric pollution stress. Comparative evaluation showed that the current status of ambient air quality is', cause for concern in metropolitan Islamabad; in terms of metal and particulate contents which in some cases were lower than some megacities of the world but higher than those of most urban, rural and background sites.

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
545.8 KB
2 1 Introduction 1-23
863.65 KB
  1.1 General Aspects Of Air Pollution 1
  1.2 Airborne Particulate Matter 7
  1.3 Air Quality And Emission Standards 12
  1.4 Air Pollution And Climatology 13
  1.5 Air Pollution In World€™s Mega Cities 17
  1.6 Air Pollution Status At Islamabad 17
  1.7 The Present Study Objectives And Perspectives 22
3 2 Analytical And Covariation Studies-A Historical Perspective 24-39
598.43 KB
  2.1 Background 24
  2.2 Recent Analytical Methodologies 25
  2.3 Miscellaneous Recent Techniques 33
  2.4 Comparative Analytical Estimations 34
  2.5 Role Of Climatic Conditions Towards Trace Metal Distribution 34
  2.6 Statistical Analysis 37
  2.7 Analytical Implications Of Particle Size Distribution 37
4 3 Experimental Methodology 40-54
505.79 KB
  3.1 Selection Of Sampling Sites And Collection Of Meteorological Data 400
  3.2 The Sampling Plan 41
  3.3 Methodology Of The Present Work 42
  3.4 Sample Collection 45
  3.5 Sample Preparation And Analysis 49
  3.6 Particle Size Analysis 51
  3.7 Statistical Analysis 53
5 4 Results And Discussion 55-96
4278.91 KB
  4.1 Layout Of Data 55
  4.2 Time Series Study For Metal Distribution 58
  4.3 Time Series Study For Metal Distribution 59
  4.4 Urban Airborne Metal Distribution 60
  4.5 Rural Airborne Metal Distribution 61
  4.6 Urban Tsp And Particle Size Distribution 62
  4.7 Rural Tsp And Particle Size Distribution 63
  4.8 Climatic Variations 63
  4.9 Correlation Study 64
  4.10 Regression Analysis 69
  4.11 Multivariate Analysis 70
  4.12 Airborne Metal Distribution For The Two Study Phases 72
  4.13 TSP And Particle Size Distribution For The Two Study Phases 72
  4.14 Climatic Variations For The Two Study Phases 73
  4.15 Correlation Study 73
  4.16 Annual Multivariate Analysis 74
  4.17 Seasonal Airborne Metal Distribution For The Two Study Phases 76
  4.18 Seasonal TSP And Particle Size Distribution For The Two Study Phases 78
  4.19 Seasonal Climatic Variates For The Two Study Phases 79
  4.20 Seasonal Correlations For The Two Study Phases 79
  4.21 Seasonal Multivariate Analysis 83
  4.22 Monthly Variations In Metal Distribution 87
  4.23 Monthly Variations In Tsp And Particle Size Distribution 89
  4.24 Comparison Of Present Metal Levels With Other Sites Around The World 90
  4.25 Salient Findings 91
  4.26 Conclusions And Recommendations 94
6 5 References 191-210
847.25 KB
  5.1 Annotated Bibliography 211
  5.2 Appendices A-H