Assessment of the contribution from wood burning to the PM10 aerosol in Flanders, Belgium

Transcription

1 Assessment of the contribution from wood burning to the PM10 aerosol in Flanders, Belgium Willy Maenhaut 1,2, Reinhilde Vermeylen 2, Magda Claeys 2, Jordy Vercauteren 3, Christina Matheeussen 3 and Edward Roekens 3 1 Ghent University (UGent), Department of Analytical Chemistry, Krijgslaan 281, S12, 9000 Gent, Belgium 2 University of Antwerp (UA), Department of Pharmaceutical Sciences, Universiteitsplein 1, 2610 Antwerpen, Belgium 3 Flemish Environment Agency (VMM), Kronenburgstraat 45, 2000 Antwerpen, Belgium Wood burning in PM10, Flanders 1

2 Introduction In Flanders (Belgium) we are struggling with too many exceedances of the 50 µg/m 3 daily PM10 mass limit in the EU : only 35 exceedances per year allowed at any given location thus, of interest to examine the cause of possible exceedances Wood burning may provide a substantial contribution to the PM10 aerosol mass, as appeared from studies in several European countries (e.g., Switzerland, Austria) Over a decade ago, Simoneit et al., AE [1999] introduced levoglucosan as an indicator for wood burning levoglucosan (C 6 H 10 O 5 ) arises from the pyrolysis of cellulose, the main building material of wood, at temperatures higher than 300 C levoglucosan is accompanied by other minor stereoisomeric monosaccharide anhydrides in atmospheric aerosols, with mannosan and galactosan being the most important ones Flemish Environment Agengy (VMM) wanted to find out what the contribution from wood burning to PM10 was over a full year for 7 sites in Flanders thereby using levoglucosan as wood burning indicator Wood burning in PM10, Flanders 2

3 Sampling From 7 February 2010 to 6 February 2011 PM10 aerosol samples simultaneously taken every 4th day at 7 monitoring sites in Flanders, Belgium on 47-mm diam. Pallflex quartz fibre filters Two of the sites (i.e., Gent and Borgerhout) are urban background sites; Mechelen is a suburban background site, and the other 4 sites are rural background sites, whereby Hamme and Lier were expected to be particularly impacted by biomass burning Wood burning in PM10, Flanders 3

4 Borgerhout : at 30 m from a busy road (Plantin en Moretuslei) Most polluted of the 2 urban background sites Wood burning in PM10, Flanders 4

5 Gent : in the Baudelo park in the North-East of the city Least polluted of the 2 urban background sites Wood burning in PM10, Flanders 5

6 Hamme : in a rural area with individual houses In the neigbourhood of the site are several inhabitants who use wood as fuel Wood burning in PM10, Flanders 6

7 Houtem : rural background site In the middle of an agricultural area in the polders Wood burning in PM10, Flanders 7

8 Meteorology Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 Of the 92 sampling days: 60 days with rain Wood burning in PM10, Flanders 8 mm, C Wind dir. (degrees) Precip. Temp. Wind dir.

9 Meteorology (cont.) Number of days NNE (0-45) ENE (45-90) ESE (90-135) SSE ( ) SSW ( ) WSW ( ) WNW ( ) NNW ( ) Wind direction mostly from South-West and North-North-East Wood burning in PM10, Flanders 9

10 Analyses PM10 mass determined by weighing of the filters at 20 C and 50% relative humidity [done by VMM] Organic, elemental, and total carbon [OC, EC, and TC (= OC + EC)] measured with a dual photo-detector (2PD) thermal-optical instrument from Sunset Lab using NIOSH temperature protocol transmission (TOT) and reflectance (TOR) simultaneously measured TOT data retained for further evaluation Levoglucosan, mannosan, and galactosan measured by gas chromatography / mass spectrometry (GC/MS) after trimethylsilylation, using method described in Pashynska et al., J. Mass Spectrom. [2002], but extraction with methanol use made of a different recovery standard (RS) and slightly modified GC temperature program employed Wood burning in PM10, Flanders 10

11 Schematic diagram of the Sunset Laboratory TOT instrument (V = valve) Wood burning in PM10, Flanders 11

12 Laser T (rel. units) He He:O2 Laser T Temp. FID Split Thermogram for Gent PM10 sample of 13 July 2010 (transmission) OC1 PC Time (s) EC Temp. ( C); FID (rel. units) OC = OC1 + PC (with PC: pyrolytic carbon) : area below the blue line prior to the OC/EC split point (vertical brown line) EC : area below the blue line after the OC/EC split point Wood burning in PM10, Flanders 12

13 Laser (rel. units) He He:O2 Laser R Laser T Temp. FID Split R Split T Thermogram for Gent PM10 sample of 13 July Temp. ( C); FID (rel. units) Time (s) 0 Full brown line : laser transmission (T) signal vertical full brown line : OC/EC split point for T Dashed purple line : laser reflectance (R) signal vertical dashed purple line : OC/EC split point for R Wood burning in PM10, Flanders 13

14 Wood burning in PM10, Flanders 14

15 Total ion current (TIC) chromatogram [relative abundance (R.A.) versus time] obtained for the sample that was collected on 23 February 2010 in Hamme. The numbered peaks are for the following compounds: 1: galactosan: 60.6 ng/cm 2 ; 2: mxp: 510 ng/cm 2 (added); 3: mannosan: 145 ng/cm 2 ; 4: levoglucosan: 826 ng/cm 2. Wood burning in PM10, Flanders 15

16 Comparison of TOT and TOR results TOR provided systematically larger EC data than TOT thus, TOR provided systematically lower OC data than TOT Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 Borgerhout, R801 Gent, R701 Mechelen, ML01 Hamme, HA02 Lier, LR02 Retie, RT01 Houtem, N029 Wood burning in PM10, Flanders 16 ECTOR/ECTOT

17 TOR/TOT ratio for EC TOR/TOT ratio for EC as a function of season Borgerhout Gent Mechelen Hamme Lier Retie Houtem ALL Spring Summer Fall Winter Some tendency for higher ratios at rural sites than at urban sites exception: Houtem Some tendency for higher ratios in winter than in the other seasons Wood burning in PM10, Flanders 17

18 TOR/TOT ratio for OC versus TC loading on filter 9 8 EC TOR /EC TOT y = x x R 2 = TC (µg/cm 2 ) Wood burning in PM10, Flanders 18

19 Time series for the PM10 mass at the 7 sites Borgerhout, R801 Gent, R701 Mechelen, ML01 Hamme, HA02 Lier, LR02 Retie, RT01 Houtem, N Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 Fairly good correlation between the data of the 7 sites At Gent: 3 samples in a row in July with elevated levels these samples taken during the Ghent City Festival Wood burning in PM10, Flanders 19 PM10 mass (µg/m 3 )

20 Retie (RT) Lier (LR) Mechelen (ML) Borgerhout (BO) Hamme (HA) Gent (GE) Houtem (HO) Wood burning in PM10, Flanders 20

21 Correlation coefficients for the PM10 mass data of the 7 sites RT LR ML BO HA GE HO Retie 1 Lier Mechelen Borgerhout Hamme Gent Houtem "Ghent City Festival" samples excluded RT LR ML BO HA GE HO Retie 1 Lier Mechelen Borgerhout Hamme Gent Houtem Wood burning in PM10, Flanders 21

22 Time series for EC at the 7 sites Borgerhout, R801 Gent, R701 Mechelen, ML01 Hamme, HA02 Lier, LR02 Retie, RT01 Houtem, N Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 ECTOT (µg/m 3 ) EC levels highest at Borgerhout, lowest at Houtem Clearly less correlation between the data from the different sites than was the case for the PM10 mass Wood burning in PM10, Flanders 22

23 Correlation coefficients for EC data of the 7 sites RT LR ML BO HA GE HO Retie 1 Lier Mechelen Borgerhout Hamme Gent Houtem Wood burning in PM10, Flanders 23

24 Median EC/TC ratios EC TOT /TC ratio for PM BO GE ML HA LR RT HO Wood burning in PM10, Flanders 24

25 Time series for OC at the 7 sites Borgerhout, R801 Gent, R701_o Gent, R701 Mechelen, ML01 Hamme, HA02 Lier, LR02 Retie, RT01 Houtem, N Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 Fairly good correlation between the data of the 7 sites At Gent: 3 samples in a row in July with elevated levels these samples taken during the Ghent City Festival Wood burning in PM10, Flanders 25 OCTOT (µg/m 3 )

26 Correlation coefficients for OC data of the 7 sites RT LR ML BO HA GE HO Retie 1 Lier Mechelen Borgerhout Hamme Gent Houtem "Ghent City Festival" samples excluded Retie 1 Lier Mechelen Borgerhout Hamme Gent Houtem Wood burning in PM10, Flanders 26

27 Gent sample of 13 July 2010 Wood burning in PM10, Flanders 27

28 Gent sample of 21 July 2010 Wood burning in PM10, Flanders 28

29 Gent sample of 29 July 2010 Wood burning in PM10, Flanders 29

30 Time series for OC at the 7 sites Borgerhout, R801 Gent, R701_o Gent, R701 Mechelen, ML01 Hamme, HA02 Lier, LR02 Retie, RT01 Houtem, N Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 Fairly good correlation between the data of the 7 sites At Gent: 3 samples in a row in July with elevated levels these samples taken during the Ghent City Festival Wood burning in PM10, Flanders 30 OCTOT (µg/m 3 )

31 Median TC/PM10_mass ratios TC/PM ratio for PM BO GE ML HA LR RT HO Wood burning in PM10, Flanders 31

32 Time series for levoglucosan at the 7 sites Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 Borgerhout, R801 Gent, R701 Mechelen, ML01 Hamme, HA02 Lier, LR02 Retie, RT01 Houtem, N029 High levels in winter & fall; low levels in spring & summer Time series for Hamme quite peculiar Wood burning in PM10, Flanders 32 Levoglucosan (µg/m 3 )

33 Correlation coefficients for levoglucosan data of the 7 sites RT LR ML BO HA GE HO Retie 1 Lier Mechelen Borgerhout Hamme Gent Houtem The levoglucosan data for 5 of the 7 sites (i.e., Retie, Lier, Mechelen, Borgerhout, and Gent) are very highly correlated with each other (all r>0.9, except 0.86 between Retie and Gent) indicating that the impact from wood burning at these 5 sites was a regional phenomenon Wood burning in PM10, Flanders 33

34 Levoglucosan (µg/m 3 ) y = 1.14x R 2 = 0.91 y = 1.12x R 2 = 0.91 y = 1.01x R 2 = 0.87 y = 0.92x R 2 = 0.91 Mechelen Lier Gent Retie Linear (Mechelen) Linear (Lier) Linear (Gent) Linear (Retie) Borgerhout - Levoglucosan (µg/m 3 ) Wood burning in PM10, Flanders 34

35 y = 1.88x R 2 = 0.32 Hamme Houtem Linear (Hamme) Linear (Houtem) Levoglucosan (µg/m 3 ) y = 0.62x R 2 = Borgerhout - Levoglucosan (µg/m 3 ) Wood burning in PM10, Flanders 35

36 Data for mannosan and galactosan A each site : mannosan and galactosan very highly correlated with each other and with levoglucosan all r > 0.95 (except at Hamme : 0.93 between levoglucosan and mannosan) Levoglucosan/mannosan (L/M) ratio depends on the type of biomass and wood burnt Miocene lignite 54 Fabbri et al., AE [2009] Peat 8.6 Kourtchev et al., STE [2011] Bituminous coal 3.1 Kourtchev et al., STE [2011] US woods, fireplaces Fine et al., EES [2004] hardwoods softwoods Austrian wood stoves Schmidl et al., AE [2008] hardwoods softwoods Wood burning in PM10, Flanders 36

37 Data for mannosan and galactosan The annual average L/M ratios for our 7 sampling sites ranged from 6.2 to 7.1 and there was little variation with season suggests that softwood burning was clearly more important than hardwood burning in Flanders in Schmidl et al., AE [2008] provided the following equation for estimating the %spruce burned from the L/M ratio : %spruce = (14.8 L/M_ratio) / this equation used to estimate the %spruce burned at our 7 sites Wood burning in PM10, Flanders 37

38 100 %spruce as a function of season %spruce Borgerhout Gent Mechelen Hamme Lier Retie Houtem ALL Spring Summer Fall Winter Typically between 70 and 80% from spruce burning little variation from site to site little variation with season Wood burning in PM10, Flanders 38

39 Contribution from wood burning to the OC and the PM10 mass To assess the percentage contribution from wood burning to the OC, we relied on the concentrations of 9.3% levoglucosan and 52% OC in wood smoke as given by Schmidl et al., AE [2008] meaning that the levoglucosan level is multiplied by a factor of 5.59 (i.e., 52/9.3) to obtain the OC concentration from wood smoke Similarly, we used the conversion factor of 10.7, suggested by Schmidl et al., AE [2008], to convert our levoglucosan concentrations to PM10 mass levels due to wood smoke Wood burning in PM10, Flanders 39

40 Time series for %OC from wood burning at the 7 sites Borgerhout, R801 Gent, R701 Mechelen, ML01 Hamme, HA02 Lier, LR02 Retie, RT01 Houtem, N Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 % of OC due to wood burning High values in winter & fall; low levels in spring & summer Time series for Hamme quite peculiar Wood burning in PM10, Flanders 40

41 70 %OC from wood burning as a function of season mean ± s.d Borgerhout Gent Mechelen Hamme Lier Retie Houtem ALL Spring Summer Fall Winter In winter (blue) for 6 of the 7 sites : around 40% of OC, on average, from wood burning At Hamme in winter : 60% of OC, on average, from wood burning Wood burning in PM10, Flanders 41

42 Annual medians of the % OC due to wood burning at the 7 sites %OC from wood burning BO GE ML HA LR RT HO Wood burning in PM10, Flanders 42

43 Time series for %PM from wood burning at the 7 sites Borgerhout, R801 Gent, R701 Mechelen, ML01 Hamme, HA02 Lier, LR02 Retie, RT01 Houtem, N Feb Feb Feb Mar Mar Apr Apr Apr May May Jun Jun Jun Jul Jul Aug Aug Aug Sep Sep Oct Oct Oct Nov Nov Nov Dec Dec Jan Jan Jan Feb-11 % of PM due to wood burning High values in winter & fall; low levels in spring & summer Time series for Hamme quite peculiar Wood burning in PM10, Flanders 43

44 25 %PM10 from wood burning as a function of season 20 mean ± s.d Borgerhout Gent Mechelen Hamme Lier Retie Houtem ALL Spring Summer Fall Winter In winter (blue) for 6 of the 7 sites : around 10% of PM10 mass, on average, from wood burning At Hamme in winter : 22% of PM10 mass, on average, from wood burning Wood burning in PM10, Flanders 44

45 Annual medians of the % PM due to wood burning at the 7 sites %PM from wood burning BO GE ML HA LR RT HO Wood burning in PM10, Flanders 45

46 Annual medians of the % EC in PM10 at the 7 sites EC TOT /PM10 perc. ratio BO GE ML HA LR RT HO Wood burning in PM10, Flanders 46

47 Summary and conclusions Wood burning is an important contributor to the OC and PM10 mass in Flanders, especially in winter 40 % of OC in winter typically from wood burning (60% at Hamme) 8% of PM10 mass in winter typically from wood burning (18% at Hamme) Since most of the exceedances of the 50 µg/m 3 daily PM10 mass limit occur in winter, reducing the wood burning emissions would help in complying with the EU limit of maximum 35 exceedances per year at any given location Wood burning smoke is a regional phenomenon in Flanders in Hamme: nearby sources very important This study published in Sci. Total Environ. Maenhaut et al., STE 437 (2012) Wood burning in PM10, Flanders 47

48 Wood burning in PM10, Flanders 48

49 Wood burning in PM10, Flanders 49

50 Mechelen : at about 1 km from the inner ring of the city Suburban background site Wood burning in PM10, Flanders 50

51 Lier : rural site; within a radius of 1 km were two horticulture farms that used wood as fuel, but it appeared in the course of the project that one of the two farms had already stopped its activities at the start of the project Wood burning in PM10, Flanders 51

52 Retie : rural background site In a meadow, next to a wooded park (Prinsenpark) Wood burning in PM10, Flanders 52

53 Gent sample of 17 July 2010 Wood burning in PM10, Flanders 53

54 Gent sample of 25 July 2010 Wood burning in PM10, Flanders 54

55 Gent sample of 2 August 2010 Wood burning in PM10, Flanders 55