Assessment of wood burning versus fossil fuel contribution  to wintertime black carbon and carbon monoxide concentrations in Athens, Greece

Kalogridis, Athina-Cerise; Vratolis, Stergios; Liakakou, Eleni; Gerasopoulos, Evangelos; Mihalopoulos, Nikolaos; Eleftheriadis, Konstantinos

doi:https://doi.org/10.5194/acp-18-10219-2018

Articles | Volume 18, issue 14

https://doi.org/10.5194/acp-18-10219-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

CHemistry and AeRosols Mediterranean EXperiments (ChArMEx)...

https://doi.org/10.5194/acp-18-10219-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 14

Research article

|

18 Jul 2018

Research article |

| 18 Jul 2018

Assessment of wood burning versus fossil fuel contribution to wintertime black carbon and carbon monoxide concentrations in Athens, Greece

Athina-Cerise Kalogridis, Stergios Vratolis, Eleni Liakakou, Evangelos Gerasopoulos, Nikolaos Mihalopoulos, and Konstantinos Eleftheriadis

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Final revised paper (published on 18 Jul 2018)
Preprint (discussion started on 16 Nov 2017)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Referee comment', Anonymous Referee #1, 19 Dec 2017
RC2: 'Complement to RC1 referee comment on the use of the CO/NOx ratio approach', Anonymous Referee #1, 21 Dec 2017
RC3: 'wood burning apportionment', Anonymous Referee #2, 22 Dec 2017
AC1: 'Authors Responses to referees' 1 & 2 comments', Athina-Cerise Kalogridis, 05 Mar 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Athina-Cerise Kalogridis on behalf of the Authors (26 Mar 2018) Author's response Manuscript

ED: Reconsider after major revisions (03 Apr 2018) by François Dulac

AR by Athina-Cerise Kalogridis on behalf of the Authors (11 Apr 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Apr 2018) by François Dulac

RR by Anonymous Referee #1 (09 May 2018)

RR by Anonymous Referee #2 (14 May 2018)

Suggestions for revision or reasons for rejection

General
The manuscript attributes the concentration-contribution of fossil fuel and wood burning to air pollution in Athens and with that handles an important health related subject that needs attention. For the source apportionment of black carbon, the well-known technique based on wavelength dependence of the aerosol light absorption coefficient is used after application of necessary compensations. The paper consciously refers to recent work. The aethalometer-model work adds a new estimate of woodburning contribution to BC. The CO source apportioning (model 2) is a new application and it is interesting to see how this will be followed up. Model 2 combined with the aethalometer model could be used as an independent estimate of bottom up emission estimates.

An important aspect in the manuscript is the conversion from deduced absorption coefficients to mass concentrations by using the MAC at 880 nm. In this paper a constant MAC (page 4line7) of 4.6 m2 g-1 is used, in the paper by Diapouli et al (2017b), from the same group using the same site and instruments, the manuscript under review is referenced with a MAC of 7.5 m2 g-1; “Kalogridis et al. calculated a MAC of 7.5 m2 g-1 for the DEM station……”. Using independent EC measurements, Diapouli found a MAC of 4.1, they however used for the compensation a C value of 3 instead of 3.5 (p3l26).- When calculating: 4.1 x3.5/3=4.8 m2 g-1 a value very close to 4.6 m2 g-1 is obtained. I understand the history of the different MAC values references in Diapouli and in this manuscript, but it should be clear to other reader too.

W.r.t. Model 2. For the source identification of CO the emission ratio of fossil fuel is determined by regression for DEM. For NOA this value is adopted. The 0.184 ppbv ng-1 m3, is a value I cannot criticize since little reference to other sources is given (Table 2 includes some values). The error 0.00137 ppbv ng-1 m3 seems to be very small and I assume that it stands model for the precision and not for the accuracy, the spread or variability is certainly much larger. When applying this error in a sensitivity calculation (page 9 top) I believed not much is to be learned. The exercise however lead to a uncertainty estimate of 25% for the woodburning ratio, that seems to be a very large value as compared to 0.00137 out of 0.184. In table 2 an independent uncertainty (accuracy) estimate for the 0.184 ppbv ng-1 m3 is presented. Moreover, I think that other quickly available ratio estimates are available. From reported emissions from traffic and household woodburning, I find the that approximately EC/CO woodburning is double EC/OC traffic (see table herebelow). This is somewhat different from the values given in Equation 19-21. Compare e.g. (my calculation) 9.5/4.3 with (manuscript) 8.8/5.4. Also the values discussed in Verma (table 2) hind to slightly bigger ratio of ratios.

ratio 2014 2015
all traffic (mix) EC/CO 0.0043 0.0040
woodburning EC/CO 0.0095 0.0093

Tabel: bottom up emission ratio estimates (kg/kg), please notice that the units are different from the units in the manuscript): EC (mass C in PM2.5)/CO (mass) for ‘woodburning’ (households only) and traffic (all road traffic! including highways, trucks)

Specific
P3line25 , ‘loading effect, i.e. the fact that the attenuation increases as light absorbing particles accumulate in the filter..’.  loading effect is the loss of linear relationship between the attenuation and surface loading. Or give a similar correct explanation.
P3line 28, ‘f values come from Drinovec’, please repeat the values in this paper. The values are valid for SSA=0.75, how do you know? Drinovec paper does not include information on SSA.
P3line32, ‘calculated for a SSA value of 0.8’, explain how
P3line32 ‘Differences were found to….’ Differences in what?
P3 Line32 ‘thus it is estimated that’ How is this estimated? In Drinovec it is discussed how this can be checked. E.g. plot the Angstrom exponent as a function of ATN.
P3line37 ‘reasonable’ what is reasonable? To my opinion this whole section is not necessary. I suggest to leave out L34 to P4line2
P4 MAC see general.
P6line8 add “source” in front of apportioning
P6 line 37 CO and BC are exclusively ..
P7L25/26 of the same order …. as (instead of than)
P8L31 ‘a relative standard deviation below 2%’ what does this imply w.r.t uncertainty, precision, and accuracy? See also my general remarks.
P8L38 I’m not familiar with the parameter size distribution when discussing a fleet mix but it comes to me as awkward.
P8L39 ‘We acknowledge…..uncertainty. The latter is difficult to be estimated with accuracy’ Please rephrase.
Figures 7 caption states: ‘(right) BCwb and BCff.’ But axis labels have BCwb and COmeasured. I think label y-axis is wrong scale is more BC-like. Please make all ranges x and y axis same. Thus e.g. BC 0-20 ng m-3 and CO 0-6000 ppb.
Figures 8 same ranges as Figure 7

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ED: Publish subject to minor revisions (review by editor) (15 May 2018) by François Dulac

AR by Athina-Cerise Kalogridis on behalf of the Authors (01 Jun 2018) Author's response Manuscript

ED: Publish subject to technical corrections (15 Jun 2018) by François Dulac

AR by Athina-Cerise Kalogridis on behalf of the Authors (28 Jun 2018) Author's response Manuscript

Short summary

Contribution of biomass burning versus fossil fuel use on wintertime air pollution is investigated based on continuous surface measurements of black carbon (BC) and carbon monoxide (CO) at a suburban and an urban background monitoring sites in Athens. Fossil fuel combustion is found to be the major contributor to both BC and CO ambient concentrations. However, wood burning used for domestic heating makes a significant contribution of about 30 and 15 % to the observed BC and CO levels.