Dispersion normalisation method for improved long-term trend evaluation: heavy metals in ambient air in the Czech Republic, Central Europe (2010–2021)

Holubová Šmejkalová, Adéla; Lhotka, Radek; Škáchová, Hana; Pacner, Jan

doi:10.5194/ar-4-441-2026

Articles | Volume 4, issue 2

https://doi.org/10.5194/ar-4-441-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/ar-4-441-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 4, issue 2

Research article

|

05 Oct 2026

Research article |

| 05 Oct 2026

Dispersion normalisation method for improved long-term trend evaluation: heavy metals in ambient air in the Czech Republic, Central Europe (2010–2021)

Adéla Holubová Šmejkalová, Radek Lhotka, Hana Škáchová, and Jan Pacner

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Final revised paper (published on 05 Oct 2026)
Supplement to the final revised paper
Preprint (discussion started on 13 Apr 2026)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on ar-2026-15', Anonymous Referee #1, 13 May 2026
This study measures the long-term trends of atmospheric heavy metals (HMs) at various station types in the Czech Republic and applies the dispersion normalization method to demonstrate that, in some cases, meteorological variability can mask the true level of emissions. The study was conducted on a robust temporal (12-year) and spatial series, with statistically significant data for measured heavy metal concentrations and correlation analyses between stations confirming the representativeness of the groups by environmental type.
Except for Ni at the industrial site, the results demonstrate statistically significant (p < 0.001) decreasing trends at all station types and for all monitored heavy metals, confirming that dispersion normalization is a robust method capable of providing clearer results on the effectiveness of legislative emission control measures.

The article presents good data quality obtained using an appropriate methodology, therefore requiring minor revisions, as suggested below:
Improve the clarity of the text in the introduction from lines 36-44.

Check and correct some errors in station abbreviations. For example, the OPR station in the text is listed as Industrial, while in Table S2 it is BS (background/suburban); in Table S2, the Industrial station is listed as Ostrava-Přívoz, which is designated POP; in all other Tables S2-S10, check the abbreviation OPO

It is recommended to improve the clarity of Figure S3 (in the Supplementary Information), for example by dividing it into multiple figures by station type or, at least, increasing the font size for easier reading
Citation: https://doi.org/10.5194/ar-2026-15-RC1
- CC1: 'Reply on RC1', Radek Lhotka, 13 May 2026
  
  We sincerely thank the reviewer for his/her thorough and constructive assessment of our manuscript. We are pleased that the reviewer found the study to be of high quality in terms of data, conducted on a robust temporal and spatial basis, and requiring only minor revisions. We will carefully consider all comments made in the comments and will revise our study accordingly.
  
  Citation: https://doi.org/10.5194/ar-2026-15-CC1
RC2:
'Comment on ar-2026-15', Anonymous Referee #2, 18 May 2026

find attached

Citation: https://doi.org/10.5194/ar-2026-15-RC2
- CC2: 'Reply on RC2', Radek Lhotka, 20 May 2026
  
  We sincerely thank the reviewer for his detailed and constructive comments. We will carefully consider all suggestions described in the comments.
  We will make linguistic and stylistic adjustments, acknowledging this deficiency in the manuscript, and will pay special attention to the results section.
  
  Citation: https://doi.org/10.5194/ar-2026-15-CC2
AC1: 'Comment on ar-2026-15', Adéla holubová, 21 Jun 2026

The response to the comments is attached. The new text is marked in green; the authors' answers are in yellow.

Citation: https://doi.org/10.5194/ar-2026-15-AC1

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload

AR by Adéla holubová on behalf of the Authors (13 Jul 2026) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (14 Jul 2026) by Daniele Contini

RR by Anonymous Referee #1 (20 Jul 2026)

RR by Anonymous Referee #2 (21 Jul 2026)

Suggestions for revision or reasons for rejection

Although the authors addressed all reviewers comments in their response letter, there are still inconsistencies which need to be eliminated before publication. I only list a few below and believe that another thorough check of the revised manuscript with submitted changes will suffice to eliminate most of them. This time, line referencing corresponds to the manuscript with track changes.

The revised section in the introduction (L42-52) now includes a comment on the results, which does not fit here. I suggest rewriting it as follows:
Consequently, air quality in this region has been steadily improving (Aas et al., 2024). Nevertheless, Central Europe remains one of the regions with the highest concentrations and deposition rates of HMs in Europe (Travnikov et al., 2020). Therefore, this study examines levels and trends in HM concentrations in relation to immission limits in the Czech Republic over the period 2010–2021. The analysis covers multiple types of environments and focuses on the effects of current regulatory measures. Dispersion normalisation is applied here for the first time in the context of HM assessment to reduce the influence of meteorological variability on observed concentrations and trends at air quality monitoring stations. To better understand these developments, this study addresses three main objectives:

The sentence in L64 now needs revision: The study aims to identify potential methodological challenges and limitations associated with the selection and grouping of monitoring stations the assessment of emission-related trends.

In L97, it is still not clear what CHMI reports and CIEP are. CHMI is only explained later in L140 while I cannot find explanation for CIEP (which also seems to be misspelled; from the response I learned CEIP – Centre on Emission Inventories and Projections, but this is not explained in the manuscript). Mind also, years in brackets still don’t always align with the citation entry (e.g. Table 1 caption).

Although the authors introduced HMOR and HMDN, they often use OR and DN throughout the manuscript, which still lack explanation. I suggest original (OR) and dispersion normalised (DN) HM concentration datasets are defined in L71, which can then be use as subscript to HM, As, Ni… later.

I still believe the sentence in L376 does not belong here. I suggest incorporating it into previous paragraph(s) or moving to Methods.

I suggest (some of the) explanation to my previous comments (refer to L232 and L254 in the original ms) is added to the manuscript.

In L278: The statistical significance results were the same for the grouped HMDN and HM datasets. -> HMDN and HMOR?

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ED: Publish subject to minor revisions (review by editor) (21 Jul 2026) by Daniele Contini

AR by Adéla holubová on behalf of the Authors (27 Jul 2026) Author's response Author's tracked changes Manuscript

ED: Publish as is (03 Aug 2026) by Daniele Contini

AR by Adéla holubová on behalf of the Authors (04 Aug 2026) Manuscript

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Short summary

This research examined whether legislative measures to reduce heavy metal pollution have been effective in the Czech Republic. We analysed 12 years of data from 16 monitoring stations and used a method that reduces the influence of changing weather. The results showed that this method is suitable for evaluating long-term trends and helps avoid errors in interpreting pollution levels affected by year-to-year weather differences.