Chemical characteristics of smoke emissions from biofuel combustion and garbage burning in central Mexico

Transcription

1 Chemical characteristics of smoke emissions from biofuel combustion and garbage burning in central Mexico Guenter Engling Department of Biomedical Engineering and Environmental Sciences National Tsing Hua University Hsinchu, Taiwan Shih-Chie Hsu 1, Bob Yokelson 2, Ted Christian 2, Beatriz Cárdenas 3, Luisa Molina 4,5 1 Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan 2 Department of Chemistry, University of Montana, Missoula, MT, USA 3 National Center for Environmental Research and Training, National Institute of Ecology/SEMARNAT, Mexico, DF, Mexico 4 Department of Earth, Atmospheric and Planetary Science, MIT, Cambridge, MA, USA 5 Molina Center for Energy and Environment, La Jolla, CA, USA

2 OUTLINE Introduction Methodology Results Conclusions Acknowledgements

3 Introduction Motivation & Objectives

4 STUDY OBJECTIVES Research Questions & Study Objectives 1. Biofuel and Biomass Combustion In addition to fossil fuels, large amounts of biomass are burned in developing countries Open burning of agricultural residues is a common practice in Asia, Africa, and Latin America Burning of garbage on small scales as well as of dump sites commonly occurs on a global basis Biofuel combustion is a common household practice for cooking in lesser developed parts of the world 2. Open Questions Estimates of biofuel use have large uncertainties, especially for developing countries Emission factors of gaseous and particulate species for many of these processes do not exist to date 3. Study Objectives Near-source measurements of emissions from representative open biomass/biofuel burning processes Estimation of emission factors of various particle-phase organic and inorganic chemical species

5 METHODOLOGY

6 Sampling Locations Measurement Sites in Central Mexico

7 Sampled Burns and Locations

8 Analysis Scheme for Filter Samples Quartz Filters Aqueous Extraction Aqu. Extraction + Acid Digestion OC/EC Analysis (TOT) Analysis by HPAEC, IC Analysis by ICP-MS

9 Smoke Characteristics PM Emissions from Biofuel Burning in Mexico

10 Open Cooking Measurements in Central Mexico

11 Open Cooking Emissions Emission Factors of Organic and Inorganic Species (g/kg fuel) Emissions Characteristics High levoglucosan emissions Open cooking fires may be an interference in estimates of total biomass burning contributions Open cooking in Mexico (and in other developing countries) may be a significant PM 2.5 source, exceeding those from fossil fuel combustion

12 Garbage Burning Open Burning Measurements in Central Mexico Garbage Dump Contents - Plastic: ~ 30% - Paper: ~ 15% - Food waste: ~ 10%

13 Garbage Burning Emissions Emission Factors of Organic and Inorganic Species (g/kg fuel) Emissions Characteristics High HCl emission factor Garbage burning may be a significant global HCl source Uniquely high Sb emissions Sb may be a good tracer for garbage burning Garbage burning in Mexico (and in other developing countries) may contribute substantially to ambient PM 2.5 loadings

14 Agricultural Residue Burning Open Burning Measurements in Central Mexico

15 Agricultural Residue Burning Emissions Emission Factors of Organic and Inorganic Species (g/kg fuel) Emissions Characteristics High Cl - and K + emissions Cl - /K + ratio (2.6) agrees well with ratios obtained from chamber burn emission measurements from straw combustion Levoglucosan/Mannosan ratio (47) is characteristically high, in good agreement with source emission values (e.g. 40 for rice straw)

16 Brick and Charcoal-Making Kilns Emissions Measurements in Central Mexico

17 Brick and Charcoal-Making Kiln Emissions Emission Factors of Organic and Inorganic Species (g/kg fuel) Emissions Characteristics High EC/OC ratio black smoke emissions Fairly high Cl - emissions possibly due to crop residue use as one of the fuels PM 2.5 mass emissions were relatively low, likely due to particle scavenging on the inner kiln walls

18 Biofuel Burning Emissions Emission Factor Variation of Trace Metals (g/kg fuel) Open Cooking Garbage Burn Brick Kiln Charcoal Kiln Stubble Burn

19 Biofuel Burning Emissions Correlation of Emission Factors of Fine PM with MCE Current study 18 Andrea and M erlet (2001) Johnson et al. (2008) 15 Roden et al. (2006) Roden et al. (2009) EF PM (g g/kg) y = x Zhang et al. (2000) Linear (all) 3 R 2 = MCE

20 CONCLUSIONS Characteristics of Biofuel Combustion Emissions in Central Mexico Open cooking fire emissions may contribute substantially to PM mass burden Garbage burning appears to be a significant source of HCl and PM emissions Field burning of crop residues can redistribute ib t agricultural l chemicals on large scales Implications and Future Research Needs Total biomass burning contributions may have an interference due to open cooking and garbage fires if typical source tracers (such as levoglucosan) are used Emissions from industrial biofuel use, such as brick and charcoal making kilns, are difficult to characterize regionally, partly due to the diverse range of fuels used Installation of improved stoves can reduce the pollutant emissions per unit fuel consumption throughout the developing world Further investigations are needed to determine representative emission factors of lesser characterized biomass/biofuel burning processes, specifically in developing countries

21 ACKNOWLEDGEMENTS Academia Sinica Dr. Shaw Liu Yi-Chih Wu, Rong-Yi Yan Yi-Tang Huang, Shu-Yung Other Collaborators Local workers, farmers, cooks