Interactive comment on “ Source attribution and process analysis for atmospheric mercury in East China simulated by CMAQ-Hg ”

Reply to Referee #1: The manuscript presents findings from a modeling study of atmospheric mercury deposition in eastern China. This study offers a valuable addition to the scientific literature by providing detailed information on mercury source attribution in a highly polluted region using a fine resolution regional photochemical model. The results will be potentially useful in the prioritization of mercury control measures for different industries in the region. Technical and editorial comments are provided below. I recommend acceptance subject to these minor revisions.

CMAQ but instead included "re-emissions" in the natural mercury emissions. This should be qualitatively discussed.
Re: Yes, we did not apply the algorithm for bidirectional mercury as the CMAQ of version 4.6 we used does not involve this subroutine. Secondary emissions that resulted from deposited mercury transformed to GEM and re-emitted to the atmosphere from soil and water were also considered as described in Shetty et al. (2008).
Q: The basis for the mercury speciation in the anthropogenic source categories should be discussed as this has a strong influence on the predicted impacts. For example, CEM is mostly GEM and thus affects GEM concentrations but has little effect on deposition, whereas IND has a strong effect on deposition.
Re: The mercury speciation in the anthropogenic source categories is given in Table 1.
Additionally, the speciation characteristics of each source category were discussed briefly in the beginning of each section for source apportionment (Section 3.2.*).

Q: The work of Zhang et al. regarding mercury in the Beijing area is relevant and
should be cited (Atmos. Chem. Phys., 13, 10505-10516, 2013).
Re: OK. We have cited this paper in our manuscript. Q: "Domestic life" is not a common source category; the basis for the sources including in this category needs to be explained.
Re: As we described in Section 2.2, emission from domestic life (DOM) includes waste incineration, domestic coal burning and application of battery and fluorescent lighting. Table 1, Figure 1 and elsewhere in the manuscript: yrˆ-1 is not scientific notation, suggest using either aˆ-1 or spell out "year".

Q: In
Re: Thank you for the comment. We have changed all "yr" in the manuscript to "year". Re: Thank you for comments before. We have proofread the entire manuscript again and check the grammar and writing style through the manuscript.

Reply to Referee #3:
This is a nice study investigating source contribution and process analysis for atmospheric mercury in a mercury-polluted region using the CMAQ-Hg model with a nested technique. The findings of this study are useful for better understanding and identifying the key factors that significantly affect atmospheric mercury level and behavior in East China. After the following comments are addressed, I recommend that the manuscript be accepted for publication.

Q: 1) Anthropogenic Hg emissions from countries around China are generally
considerably large and apparently were not considered in this study (Fig. 1a). Those emissions could significantly affect atmospheric Hg level and behavior in China. Thus they could significantly alter modeled results presented in this paper. The potential impact of neglecting those emissions should be discussed in the manuscript.
Re: We have added some uncertainty analysis for underestimate the anthropogenic sources from other countries in Section 3.2.7. It would lead to the underestimate the contribution from out of China. We will improve the accuracy of anthropogenic sources out of China in the future work. Re: GEOS-CHEM output we used with spatial resolution of 4°*4.5°and temporal resolution of one hour. The output from GEOS-CHEM can be used as the boundary condition for CMAQ with interpolation. However, the coarser resolution will lead to uncertainty for CMAQ modeling results.

Q: 4) In section 3.2, the manuscript presents many numbers and points, but doesn't
give sufficient and specific figure citations to support them. It is really difficult for readers to figure them out.
Re: Figure 4 and Figure 5 are used to support section 3.2. Because there are too many categories of emission sources to be compared, it is difficult to express all information in one or two figures and also we cannot show too many figures due to the limited space available for publication.

Technical comments
Q: P10390 L5: "run with nested grid resolution of 27km" to "run with a nested