New reactive nitrogen chemistry reshapes the relationship of ozone to its precursors 1

Transcription

1 Supporting information: New reactive nitrogen chemistry reshapes the relationship of ozone to its precursors 1 Qinyi LI 1, Li ZHANG 1, Tao WANG 1*, Zhe WANG 1, Xiao FU 1 and Qiang ZHANG 2 Contents S1. The emission matrix for the WRF-Chem simulations - S2 - S2. Reactive chlorine emission inventory of China. - S3 - S3. The definition of O3 sensitivity in chemical transport model study. - S6 - Reference. - S Content summary: Number of pages: 6 Number of figures: 3 Number of tables: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, , China; 2 Center for Earth System Science, Tsinghua University, Beijing, , China Now at: Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, New Jersey, 08544, United States; Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, New Jersey, 08544, United States *Corresponding author: Tao Wang (cetwang@polyu.edu.hk) S1

2 18 S1. The emission matrix for the WRF-Chem simulations 100 Anthrpogneic emission of NOx (%) Anthropogenic emission of VOC (%) Fig. S1. The emission matrix for the WRF-Chem simulations. The blue square represents the emission scenario for the evaluation of the changes of RO x and NO x levels due to the nitrogen chemistry. The red triangles represent the emission reduction scenarios used for the determination of the O 3 sensitivity regimes. The black crosses represent the emission scenarios used for the O 3 isopleth analysis S2

3 S2. Reactive chlorine emission inventory of China In this study, we updated the chlorine emission inventory in China following the compilation method in RCEI 1 and using the updated activity data in China. As estimated in the RCEI, coal burning and biomass burning dominate the anthropogenic reactive chlorine emission in China. Therefore, in this study, we updated the national inventory for chlorine emissions from the two sources. As in RCEI, the estimation of chlorine emission from coal burning is calculated by multiplying the activity level (i.e. the coal consumption data, CC) and the emission factor (EF): EHCl=CC*EFHCl (Eq. S1) EFHCl=(36.5/35.5)*Cl*(1-η) (Eq. S2) in which, Cl denotes the chlorine content in coal, η represents the removal efficiency of the control technology. The coal consumption can be either retrieved from statistic data, or derived from the available emission of an air pollutant from the coal burning, and the latter method is adopted in this study. Emission data of sulphur dioxide in the Multi-resolution Emission Inventory of China, developed in Tsinghua University ( is chosen to derive the coal consumption in China since the emission of sulphur dioxide in China is mostly (~90%) attributed to coal consumption. 2 In this study, we treat that all the SO 2 emission as the emission from coal burning, thus, the coal consumption (CC) can be quantified according to the SO 2 emission (ESO 2) and emission factor of SO 2, following the equation S3 and S4: ESO 2 =CC*EFSO 2 (Eq. S3) EFSO 2 =2*S*(1-SR)*(1-η) (Eq. S4) in which, S denotes the sulphur content in coal (1%), while SR represents the sulphur retention rate (10%), and η is the removal efficiency of the control technology and is assumed to be the same as that in equation S2. The emission of chlorine can be calculated by combining the equations S1 to S4: 55 =.... (Eq. S5) S3

4 The chlorine content in the coal varies in different types of coal. Zhang et al. reported values ranging from 40 to 407 mg/kg in the coals sampled in 177 mines in China. 3 Ren et al. measured 137 samples of coal produced in China and found the content of chlorine between and 1865 mg/kg. 4 In this study, we used the highest value to our knowledge, 1865 mg/kg (0.1865%), to account for other possible chlorine sources that are not included in this study, such as water treatment, waste treatment, agricultural activities, salty land, swimming pools, etc. The estimation of chlorine emission from biomass burning is calculated based on the emission of CO according to the method used in RCEI. 1, 5 The emission of chlorine is estimated to be 7.4*10-3 times of the moles of the CO emission in the RCEI study. The emission of CO from biomass burning is retrieved from the high-resolution global emission inventory, EDGAR emission inventory ( including the CO emission from agricultural waste burning and large scale biomass burning. Integrating both the emission of chlorine from coal and biomass burning, we compiled the monthly emission inventory for reactive chlorine for China, RCEI-China, see Fig S2 for the emission in July. The emission of chlorine from coal burning and that from biomass burning vary in time and locations, and overall, coal burning activity contributed the majority of chlorine emission in China based on our estimate. Chlorine emission in China demonstrates a distinguished regional pattern, and the five major city clusters, NCP, YRD, PRD, CC and SCB, emit intensive chlorine. The spatial pattern from RCEI-China is consistent with the global dataset, RCEI, as shown in Fig S3. The RCEI-China shows higher emission intensity in the five city clusters (>0.05 µg m -2 s -1 ) than the RCEI (<0.04 µg m -2 s -1 ) and RCEI-China provides finer details because of the higher resolution (0.25x0.25 degree) compared to RCEI (1x1 degree). S4

5 79 80 Fig S2. Chorine emission intensity in China from RCEI-China in July Fig S3. Chlorine emission intensity in China from RCEI S5

6 S3. The definition of O 3 sensitivity in chemical transport model study In this study, we adopted the definition of the sensitivity of O3 production to its precursor proposed by Sillman and West. 6 A location of NO x -sensitive (VOC-sensitive) means that at this location the O 3 decreases by at least 5 ppb due to the reduced NO x emission (VOC emission) and if the decrease of O 3 in response to reduced NO x emission (VOC emission) is at least twice as large as the decrease in O 3 due to the reduced VOC emission (NO x emission). One site is determined as in VOC-sensitive regime if O 3 is reduced by more than 5 ppb in response to decreased VOC emission and if O 3 enhances in response to the reduced NO x emission. A region is defined as in mixed-sensitive regime provided O 3 drops by equal or more than 5 ppb due to either reduced VOC or NO x emission and if the reduction of O 3 because of the decreased VOC and the NO x emission differ by less than a factor of two. An area is dominated by the regime of NO x titration if the O 3 enhances by more than 5 ppb due to the NO x emission reduction but decrease less than 5 ppb because of the VOC emission reduction. A grid that demonstrates less than 5 ppb changes due to the reduction of either NOx or VOC emission is determined as having no sensitivity. Reference: 1. Keene, W. C.; Khalil, A. M. K.; Erickson, D. J.; McCulloch, A.; Graedel, T. E.; Lobert, J. M.; Aucott, M. L.; Gong, S.; Harper, D. B.; Kleiman, G.; Midgley, P.; Moore, R. M.; Seuzaret, C.; Sturges, W. T.; Benkovitz, C. M.; Koropalov, V.; Barrie, L. A.; Li, Y., Composite global emissions of reactive chlorine from anthropogenic and natural sources: Reactive Chlorine Emissions Inventory. Journal of Geophysical Research: Atmospheres ( ) 1999, 104, (D7), Lu, Z.; Zhang, Q.; Streets, D. G., Sulfur dioxide and primary carbonaceous aerosol emissions in China and India, Atmospheric Chemistry and Physics 2011, 11, (18), Zhang, L.; Wang, S.; Meng, Y.; Hao, J., Influence of Mercury and Chlorine Content of Coal on Mercury Emissions from Coal-Fired Power Plants in China. Environmental Science & Technology 2012, 46, (11), Ren, D.; Zhao, F.; Wang, Y.; Yang, S., Distributions of minor and trace elements in Chinese coals. International Journal of Coal Geology 1999, 40, (2-3), Lobert, J. M.; Keene, W. C.; Logan, J. A.; Yevich, R., Global chlorine emissions from biomass burning: Reactive Chlorine Emissions Inventory. Journal of Geophysical Research: Atmospheres ( ) 1999, 104, (D7), S6

7 Sillman, S.; West, J., Reactive nitrogen in Mexico City and its relation to ozone-precursor sensitivity: results from photochemical models. Atmospheric Chemistry and Physics 2009, 9, (11), S7