Source Contributions to Rural Carbonaceous Winter Aerosol in North-Eastern Poland

Round 1

Reviewer 1 Report

Review of ‘Source contribution to rural carbonaceous winter aerosol in north-eastern Poland’

Kristensson and coauthors describe a winter measurement campaign aimed at apportioning sources of carbonaceous matter in ambient aerosol impacting background air quality in northeastern Poland in the wintertime. At 24-hour resolution OC and EC were quantified off-line using a thermal-optical instrument, levoglucosan was quantified off-line using GC-MS. Real-time multiwavelength aethalometer data were used to quantify eBC. Levoglucosan was used as a tracer to estimate the contribution of woodburning to CM. An attempt was made to separate traffic, woodburning and coal-burning contributions to BC. Likely source regions were identified using back-trajectory analysis. Cities to the south contribute to wood burning/coal burning while cities to the southeast and southwest contribute to traffic CM. While the methods used here are typical for this kind of air quality study the absence of data for Poland makes the dataset interesting and worthwhile. I have a few comments on the approach.

Major comments:

I don’t understand the justification for changing the aethalometer model wavelength pair to both be at shorter wavelengths. The reason a near-UV and near-IR pair is traditionally used is because only BC absorbs at longer wavelengths while in the UV-visible range both BC and brown carbon (eg from wood burning) absorb. The model is based on this behavior. I think sticking with the traditional wavelength pair would work just fine here, especially when it is actually the levoglucosan data that are used to separate wood and coal burning contributions to BC.

This follows on to the second comment, separating wood and coal contributions to BC. I understand how the levoglucosan/OC ratio is used to estimate its contribution to CM. However the aethalometer model deals exclusively with BC. In order to subtract the woodburning BC contribution from the wood+coal BC, the wood burning BC first needs to be determined. How is this determined from the wood burning CM? An explanation of this is needed in the text.

More detail is needed on the aethalometer operation. What tape type was used, what C value for scattering was assumed, and most importantly, how was filter loading compensated for? The AE33 model may inherently correct for this using the dual-spot approach but this needs to be specified.

Sensitivity analyses discussed should be included as tables, eg in a supporting information document.

 Why is there zero traffic BC contribution from the cities of Katowice and Krakow?

The ratio of 1.76 between eBC and thermal/optical EC does not necessarily indicate poor agreement. This is more related to the default assumed MAC value. Slopes of around 1.7 are actually observed at several locations, even in the absence of heavily coated BC, eg (Healy et al., 2017) and references for Europe within.

Is there a diurnal dependence for hourly aethalometer traffic BC and residential burning BC? This could validate the source assignments, although for long-range transport this will be less helpful.

In Figure 3 the disappearance of the woodburning contribution is not consistent with the periods when it is present. There seems to be a fairly stable ratio between wood and coal contributions when the wood is present, so it is unlikely that the contribution should be zero on the other days. Even simply reporting these two sources as a mixed source would be fine. As stated in the conclusions an optical method it is not really well suited to this. Good separation of fossil fuel and biomass BC has been derived at European sites using single particle mass spectrometry for example.

Minor comments

PM₁ and PM­_­2.5 should be subscript throughout.

Line 30 ‘estimated to be’

Line 51 ‘coefficient’

Line 76 ‘AAEs’

Line 94 ‘recent advances’

Line 100 ’29.3’

Figure 3 rephrase last line of caption

 

References

Healy, R.M., Sofowote, U., Su, Y., Debosz, J., Noble, M., Jeong, C.H., Wang, J.M., Hilker, N., Evans, G.J., Doerksen, G., Jones, K., Munoz, A., 2017. Ambient measurements and source apportionment of fossil fuel and biomass burning black carbon in Ontario. Atmospheric Environment 161, 34-47.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Please find the comments in the document attached. 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors,

I like the paper, however, the Abstract provides a little bit of false information. There have been a number of research papers describing aerosol concentrations in Poland. Please provide some reference regarding these works (or the ones that are relevant to your work). There is also a ongoing aerosol measurements run in several locations in Poland and they are made within the framework of the POLAND-AOD program. Please, have a look at the system and may have some reference to your work. Some examples of the papers include the following works:

Aerosol Properties and Radiative Forcing for Three Air Masses Transported in Summer 2011 to Sopot, Poland, Radiation Processes in the Atmosphere and Ocean (IRS2012), 1531, 504-507, doi:10.1063/1.48048172013, Rozwadowska A., Stachlewska I.S., Makuch P., Markowicz K.M., Petelski T., Strzalkowska, A., Zielinski T., 2013.

Studies of aerosol optical depth with use of Microtops sun photometers and MODIS detectors in the coastal areas of the Baltic Sea, Acta Geophysica, vol. 62, no. 2, Apr. 2014, pp. 400-422, DOI: 10.2478/s11600-013-0182-5, O. Zawadzka, P. Makuch, K.M. Markowicz, T. Zielinski, T. Petelski, V. Ulevicius, A. Strzalkowska, A. Rozwadowska, D. Gutowska, 2014.

Impact of wild forest fires in Eastern Europe on aerosol composition and particle optical properties; Oceanologia; Vol. 58(1), 13-24; doi:10.1016/j.oceano.2015.07.005; T. Zielinski, T. Petelski, A. Strzalkowska, P. Pakszys, P. Makuch, 2016.

Study of aerosol optical properties during long-range transport of biomass burning from Canada to Central Europe in July 2013; Journal of Aerosol Science; Vol. 101, 156 -173; K. M. Markowicz, M.T.Chilinski, J. Lisok, O. Zawadzka, L. Janicka, I.S. Stachlewska, P. Makuch, P. Pakszys, A. Rozwadowska, Petelski, T. Zielinski, M. Posyniak, A. Pietruczuk, A. Szkop, D. L. Westphal, 2016.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I appreciate the authors carefully modified their manuscript. I only have one comment.

 

Original comment: Where is Lithuania on the map?

Authors Answer: We have referenced to Figure 1 in the manuscript to show where Lithuania is.

 

 

I don't think Lithuania is referenced to Figure 1 in the first sentence of Line Section 2.2 in the updated manuscript as stated by the author. 

 

As long as the author can have this fixed, this manuscript can be accepted.

Author Response

Dear reviewer no. 2. Thank you for pointing this out. Indeed, we have made a mistake and missed to write the reference to Figure 1 in the text in section 2.2. We have now provided a new revised version of the manuscript with the following addition at lines 148-149:

"Preila environmental pollution research station (55°55’N, 21°00’E, 5 m above sea level, [51]) is located in the Curonian Spit in Lithuania and represents a rural coastal environment (Figure 1)."