Air quality expert group - Fine particulate matter (PM2.5) in ... - Defra

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PM2.5 emissions and receptor modelling background sites, it was shown that the mass of particles making up the roadside increment (i.e. the difference between the roadside concentration and the urban background) was comprised almost wholly of elemental carbon (54.8%), organic carbon (27.4%) and road dust (18.3%) (Harrison et al., 2004). Table 4.5: Adjustment factors used in mass closure (Harrison et al., 2003). Analyte Conversion to Numerical factor sulphate (NH4) 2SO4 * 1.38 hydrate 1.29 nitrate (fine) NH 4NO 3 1.29 hydrate 1.29 nitrate (coarse) NaNO 3 1.37 hydrate 1.29 chloride NaCl 1.65 calcium CaSO 4.2H 2O 4.30 iron soil/road dust 5.50 (roadside) 9.00 (background) 3.50 (roadside increment) elemental carbon elemental carbon 1.00 organic carbon organic compounds 1.30 (roadside) 1.40 (background) 1.20 (roadside increment) * After subtraction of sulphate derived from gypsum (CaSO 4.2H 2O). 83. This method was subsequently applied by Yin and Harrison (2008) to samples of PM1.0, PM2.5 and PM10 from roadside, urban background and rural sites in the West Midlands. The method was shown to account well for the gravimetricallymeasured mass of particles without invoking the presence of bound water, which the authors attributed to the lower humidity in the weighing room compared to the previous study. The results for PM2.5 at the urban background Birmingham City Centre site on all days and on days when PM10 exceeded 50 µg m -3 (episode days) appear in Figure 3.17 in Chapter 3. A number of points can be drawn from this average account of particle mass: • secondary sulphates and nitrates make up a very large proportion of average PM2.5 mass; • nitrate tends to dominate mass on high pollution days, defined as when PM10 exceeds 50 µg m -3 ; and • there are substantial contributions from organic compounds and iron-rich road dusts which are likely to include contributions from a range of sources. 84. In a further paper, Harrison and Yin (2008) analysed the data for organic and elemental carbon from their mass closure study. They calculated separate concentrations of primary and secondary organic carbon based upon the “elemental carbon tracer method” of Castro et al. (1999). This method 109
PM2.5 in the UK 110 is predicated on the assumption that emissions of elemental carbon from combustion sources are always accompanied by a constant proportion of organic carbon, and that the ratio of OC to EC in those primary emissions is equal to the minimum ratio observed in atmospheric measurements. An interesting finding was that secondary organic carbon showed a marked seasonal variation, shown in Figure 4.9, which closely paralleled that of nitrate but not sulphate in PM2.5. This is strongly suggestive of the semi-volatile nature of secondary organic matter, broadly paralleling the semi-volatility of ammonium nitrate, and hence leading to higher concentrations in the cooler parts of the year and substantial evaporation in the summer months. The observed peak in April, which has been observed in March or April data for nitrate in many years, is thought to arise from a combination of the prevalence of advection of continental air masses in the spring combined with low average atmospheric temperatures. Concentration (µgm-3) 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 PM2.5 – BCCS Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month SecOC NO3 SO4 Figure 4.9: Monthly mean concentrations of secondary OC, nitrate and sulphate in PM2.5 at the Birmingham City Centre site (BCSS) (urban centre) (Yin et al., 2010). 85. The examination of differences between roadside, urban background and rural sites also led to the following conclusions: (a) There is a substantial regional background of organic carbon consisting of long-lived primary compounds and secondary species. This tends to dominate the overall concentration of organic carbon. (b) Superimposed upon the regional background described by rural measurements is an urban increment of mainly elemental carbon with a composition consistent with that of road traffic emissions, but not with wood burning emissions. (c) Roadside samples contain an additional EC-rich contribution due to vehicle emissions. In this traffic-generated increment, elemental carbon typically accounts for about 70% of total carbon.
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AIR QUALITY EXPERT GROUP Fine Parti
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This is a report from the Air Quali
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II Membership Chair Professor Paul
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IV Acknowledgements The Air Quality
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VI 2.5 Summary 39 2.5.1 What does t
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VIII 5.4 Components of PM2.5 and so
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PM2.5 in the UK 2 Air Quality Direc
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PM2.5 in the UK 4 I.2.1 Concentrati
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PM2.5 in the UK 6 • PM2.5 emissio
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PM2.5 in the UK 8 I.4.1 Modelling r
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PM2.5 in the UK 10 4. In broad term
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PM2.5 in the UK Table 1.2: National
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PM2.5 in the UK 14 17. Dry depositi
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PM2.5 in the UK 16 in ozone in the
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PM2.5 in the UK 18
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PM2.5 in the UK 20 5. The exact for
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PM2.5 in the UK 22 12. These diffic
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PM2.5 in the UK 24 2.3 Methods used
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PM2.5 in the UK 26 (e) During the
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PM2.5 in the UK 28 2.3.3 The Partis
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PM2.5 in the UK 30 35. For non-auto
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PM2.5 in the UK 32 43. Ratification
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PM2.5 in the UK 34 49. Many of the
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PM2.5 in the UK 36 57. Black carbon
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PM2.5 in the UK 38 2.4.4 PM2.5 elem
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PM2.5 in the UK 40 average of 93.6%
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PM2.5 in the UK Annex 1 - PM2.5 mon
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PM2.5 in the UK 44
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PM2.5 in the UK 46 3.2.1 Diurnal va
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PM2.5 in the UK 48 PM2.5/µgm -3 20
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PM2.5 in the UK 50 3.2.4 Seasonal v
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PM2.5 in the UK 52 12. Results are
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PM2.5 in the UK 54 3.4.2 Relationsh
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PM2.5 in the UK 56 Correlation 0.8
Page 69 and 70: PM2.5 in the UK Figure 3.11: Polar
Page 71 and 72: PM2.5 in the UK 60 south. Further a
Page 73 and 74: PM2.5 in the UK 62 3.7 PM2.5 episod
Page 75 and 76: PM2.5 in the UK 64 secondary ammoni
Page 77 and 78: PM2.5 in the UK 66 3.8 PM2.5 concen
Page 79 and 80: PM2.5 in the UK 68 3.9 Composition
Page 81 and 82: PM2.5 in the UK 70 43. The UK has i
Page 83 and 84: PM2.5 in the UK 72 NO 3 6 4 2 2000
Page 85 and 86: PM2.5 in the UK 74 54. PM ammonium
Page 87 and 88: PM2.5 in the UK 76 58. Data from th
Page 89 and 90: PM2.5 in the UK 78 (k) Road traffic
Page 91 and 92: PM2.5 in the UK 80 provided by spec
Page 93 and 94: PM2.5 in the UK 82 14. The London L
Page 95 and 96: PM2.5 in the UK Table 4.1: UK emiss
Page 97 and 98: PM2.5 in the UK 86 24. National inv
Page 99 and 100: PM2.5 in the UK 88 Figure 4.5: Spat
Page 101 and 102: PM2.5 in the UK 90 either nanoparti
Page 103 and 104: PM2.5 in the UK 92 37. Further cons
Page 105 and 106: PM2.5 in the UK Emissions (ktonnes)
Page 107 and 108: PM2.5 in the UK 96 Figure 4.7: Spat
Page 109 and 110: PM2.5 in the UK 98 4.4 A critical a
Page 111 and 112: PM2.5 in the UK 100 60. At a local
Page 113 and 114: PM2.5 in the UK 102 measurements an
Page 115 and 116: PM2.5 in the UK 104 4.5.2 Quantifyi
Page 117 and 118: PM2.5 in the UK 106 77. Early effor
Page 119: PM2.5 in the UK 108 4.6.1 Receptor
Page 123 and 124: PM2.5 in the UK 112 PM2.5 contribut
Page 125 and 126: PM2.5 in the UK 114 inorganic parti
Page 127 and 128: PM2.5 in the UK 116 93. While there
Page 129 and 130: PM2.5 in the UK 118 100% 90% 80% 70
Page 131 and 132: PM2.5 in the UK 120 105. Receptor m
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Page 135 and 136: PM2.5 in the UK 124 5. At the regio
Page 137 and 138: PM2.5 in the UK 126 15. Some of the
Page 139 and 140: PM2.5 in the UK 128 Figure 5.2: Tot
Page 141 and 142: PM2.5 in the UK 130 µgm -3 160 140
Page 143 and 144: PM2.5 in the UK 132 PM component (
Page 145 and 146: PM2.5 in the UK 134 with larger dev
Page 147 and 148: PM2.5 in the UK 136 Figure 5.8: UKI
Page 149 and 150: PM2.5 in the UK Figure 5.9: Compari
Page 151 and 152: PM2.5 in the UK 140 PM2.5 concentra
Page 153 and 154: PM2.5 in the UK 142 the North Sea (
Page 155 and 156: PM2.5 in the UK 144 53. Modelling r
Page 157 and 158: PM2.5 in the UK Annex 2: PM modelli
Page 159 and 160: PM2.5 in the UK 148 2. Figure A2.1.
Page 161 and 162: PM2.5 in the UK 150 6. The non-line
Page 163 and 164: PM2.5 in the UK 152 Model 50 45 40
Page 165 and 166: PM2.5 in the UK 154 (a) (b) modPM 2
Page 167 and 168: PM2.5 in the UK 156 NO3 - concentra
Page 169 and 170: PM2.5 in the UK 158 26. This was in
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PM2.5 in the UK 160 SIA components
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PM2.5 in the UK 162 x 50 km grid fo
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PM2.5 in the UK 164 A2.6: Photochem
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PM2.5 in the UK 166 PM2.5 Emission
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PM2.5 in the UK 168 A2.8: PCM PM mo
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PM2.5 in the UK 170 illustrated by
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PM2.5 in the UK 172 trajectory mode
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PM2.5 in the UK 174
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PM2.5 in the UK 176 4. The delivery
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PM2.5 in the UK 178 12. With respec
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PM2.5 in the UK 180
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PM2.5 in the UK Chapter 2: Measurin
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PM2.5 in the UK RoTAP (2012). Revie
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PM2.5 in the UK Harrison R.M. and Y
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PM2.5 in the UK Chapter 5 Modelling
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PM2.5 in the UK Jones A.M., Harriso
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PB13837 Nobel House 17 Smith Square
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