I find the manuscript highly informative, as it provides a comprehensive long-term dataset on benthic phosphorus fluxes in the Baltic Sea, offering valuable insights into nutrient cycling and contributing to more effective management of coastal eutrophication. I also appreciate the discussion of the study's limitations and the well-considered suggestions for future research directions.

General Comments:

1. In the first sentence of the abstract, I recommend avoiding exclusive emphasis on coastal eutrophication, as phosphorus recycling is a process of broader significance across marine ecosystems. Furthermore, the majority of the data presented in the study are not from coastal environments, so a more general framing would be more appropriate.
2. Please provide the source of the oxygen data used in Figure 1. If the data were collected as part of this study and extrapolated, a detailed description of the methodology should be included in the Methods section.
3. According to many standard recommendations for phosphate sample collection and preservation, filtration (typically at 0.45 µm) is required to remove suspended particles and microorganisms. If unfiltered samples were used, a turbidity blank must be applied to correct for potential interference. Additionally, acidification is generally not advised for phosphate preservation. Given that various collection and preservation methods appear to have been used in this study, please discuss the uncertainties this introduces into the fluxes and extrapolations.
4. I assume that samples were analyzed in different laboratories. If so, please provide detailed information on the accuracy and precision of the analytical methods used, as this can significantly affect the comparability of the results and calculations.
5. The authors state that the dataset has limited use for interpreting seasonal trends. However, it would be interesting to deliberate a bit on the temporal variability at stations where monthly coverage was substantial, such as KH104.

Editorial Comments:

1. Consider whether the use of the symbol “>” is necessary when the full range (0–63 µM O₂) is already explicitly stated.

This manuscript offers a valuable compilation of dissolved inorganic phosphorus (DIP) flux measurements collected across multiple research cruises, encompassing diverse spatial and temporal scales. While portions of the data have been previously published or referenced in various forms, the authors present a new perspective that yields novel insights into DIP flux patterns. The work makes a meaningful contribution to the field and, following appropriate revisions, merits publication in this journal. See my general comments:

Abstract

Line 30: When you say that the data is of high quality. Question is in terms of what? I don’t think this quality was estimated, even though everything was likely done correctly. Although I agree that the present study compiling DIP fluxes is important for evaluating and implementing the Marine Strategy Directives, I am less convinced of its novelty in studying the mechanism of phosphorus cycling.

Introduction

Lines 63-64: The sentence is redundant and suggests omitting.

Lines 67-68: The sentence is redundant and suggests omitting. The description of the Gulf of Finland needs to be reformulated.

Lines 72-73: Again, I don’t necessarily need to include information on catchment, as you don’t discuss it later.

Line 77: What gives this sentence? The following sentence provides a more straightforward explanation for the accumulation of higher P in the water column.

Line 99: digit in “O2” should be in subscript.

Lines 107-110/Line 146-150: Could you briefly discuss whether using different chambers could raise some differences in measured fluxes?

Lines 155-157: Could you state/discuss briefly that a different sample treatment had no effect on the level of DIP in the sample and measurement accuracy?

Line 178: Make a space between the dot and “Positive”.

Results and Discussion

Line 255: Could you add parentheses to the range of months for each season?

Lines 234-235: Maybe I have missed, but I am curious how authors obtained a common value from “non-significant” and “significant” values for the same site/area.

Lines 234-240: Would it be beneficial for authors to describe more variability in DIP fluxes and present the variation coefficients?

Figures

Figure 3: The digit in “O2” should be in subscript

The manuscript presents a dataset on benthic dissolved inorganic phosphorus (DIP) fluxes in the Baltic Sea, highlighting spatial and temporal variations in relation to the extent of deep-water deoxygenation and the underlying sediment types. The dataset is remarkable, particularly because it was obtained through in situ measurements. I especially appreciated the effort made to harmonize the data and to ensure its robustness. This manuscript represents a valuable contribution to the marine biogeochemistry community as well as to researchers interested in coastal deoxygenation processes.

That said, several points would benefit from clarification, particularly to ensure that readers who are not specialists of the Baltic Sea can easily follow and fully grasp the information provided. 

I have included my detailed comments in the attached document.