Dear authors. The two reviewers still have significant reservations about this manuscript, and recommend either a rejection (reviewer #1) or a major revision (reviewer #2). I have read the revised manuscript, and while I can see improvements relative to the originally submitted version, I have to agree with the reviewers that major improvements are necessary. Broadly speaking, the manuscript needs a stronger emphasis on the novel aspects of this work, as well as a complete overhaul of the cited literature. For example, quite a few papers on aerosol photodegradation are not mentioned, and less relevant papers are cited instead. There are some technical issues raised by the reviewers as well, such as the need to better diagrams (instead of photos) of the experimental setup and presenting mass-normalized absorption data instead of using arbitrary units. You have a couple of choices at this point. You may elect to produce a 2nd revision of the manuscript, which will be reviewed again by the same reviewers (both of whom have significant expertise in both particulate matter and dissolved organic matter photochemistry). If you do not think the reviewers comments can be addressed you may elect to take no action, in which case the manuscript will remain published in ACPD but will not proceed to the final publication in ACP.

Dear authors. I should be able to accept the paper after one more round of addressing the reviewers' comments. I may ask you for minor technical corrections for the final version before the acceptance after reading the next revision of the manuscript but I will not send it to reviewers anymore.

Dear authors. I have examined the final version of the manuscript, and while I think it could be further improved with more precise wording choices, I do not think another round of review is going to help. The results are certainly useful, and deserve to be published, so I am going to go ahead with the acceptance. The manuscript still has an unusually large number of typos, grammatical mistakes, and imprecise wording choices. For example, below is a partial list from the first two paragraphs in the paper. I am going to ask Copernicus (ACP publisher) about their copy-editing services but it is better if they start with a cleaner version. Therefore, please go through the text one more time, perhaps enlisting your own professional editing services.

L24: mainly originates from -> is an important component of
L25: emission -> emissions
L27: absorption for -> absorption of
L27: (Wavelength -> (wavelength
L29: atmospheric components and quality -> air quality
L32: As photosensitive substances, the -> The
L34: that due to COM is -> due to
L36: because -> when
L37: the sentence needs to be broken in two sentences
L39: spectral -> spectral range
L43: delete “could be”
… and so on – there are too many mistakes to list here.