Dear Authors,
I have now received comments from all two reviewers. I Invite you to respond to comments from both reviewers for your manuscript to be accepted for publication. Please find attached the comments from both reviewers.

Reviewer 1

Summary of the Study
A descriptive study examining the mechanisms regulating the distribution of iron (Fe) and manganese
(Mn) trace metals in the Arctic's Laptev and East Siberian Seas based on in-situ measurements.
Overall, they find that river discharge and shelf sediment-water exchange processes are essential
sources of Fe and Mn in this region. Contrasting the East Siberian Sea (ESS) and Chukchi Abyssal
Plain (CAP) with the Makarov Basin (MB) and Amundsen Basin (AB), they find significant
differences driven by source waters and biological activity. Surface waters in the ESS and CAP are
generally enriched in Mn but depleted in Fe compared to those in the AB and MB. The ESS receives
nutrients and trace metals from Pacific waters, in contrast to the Atlantic waters found in the MB and
AB. Biological control of Fe through ligand complexation is a key mechanism, resulting in Fe
predominantly existing in a particulate phase while Mn remains in the dissolved phase on the shelf.

Major comments
The in-depth characterization of the Arctic's Laptev and East Siberian Seas provided here is an
essential contribution to understanding the biogeochemical and physical processes controlling trace
metals budgets, especially given the recent accelerating changes in the region. The authors present a
compelling mechanistic synthesis, but the manuscript requires refinement in its presentation. Overall,
the manuscript is generally grammatically clean. However, it needs improvements in structure and
readability. First, the manuscript reads more like a report or book chapter, overly descriptive and
lacking a clear hypothesis, or answering specific questions. Though a valuable contribution, it is
unclear why readers should read it. For instance, focusing on contrasting the physical and
biogeochemical controls of iron (Fe) and manganese (Mn) in the Arctic's Laptev and East Siberian
Seas could provide a better framework for the study. Second, the labeling of the figures is inadequate;
nearly all figures lack titles, necessitating readers to refer to figure descriptions for context. Moreover,
the figure descriptions do not adequately explain the terms used, and there is a notable presence of
technical jargon throughout the study. Third, the manuscript overuses acronyms, which can hinder
readability. Finally, some sentences contain incomplete reasoning, which detracts from the overall
coherence of the manuscript. Below, I highlight few examples.

Minor comments
Line 165: Too many acronyms already, you don’t need S and T for temperature and salinity.
Line 165: “The T of water above 25 m exceeded 0°C at 125−145 °E (Figs. S1 and S2), owing to the
atmospheric radiative forcing” It is not clear what you mean in this sentence. What does radiative
forcing have to do with surface ocean temperature? These two concepts are obviously related, but it is
unclear how you are using them
Line 190: Define the terms in your figures.
Line 215: “In contrast, a negative value of fsim along the continental slope suggests that sea ice
formation is dominant in the region,” which region?
Figure 4: Same issue with Figure 3, but you sometimes use full names. Be consistent..
Line 255: {The dMn concentration in the surface waters gradually increased with decreasing salinity,
whereas the dFe concentration did not show a similar increasing trend (Fig. 5)} This statement is not a
complete interpretation of figure 5, can you explain the exceptions

Reviewer 2
This research investigates the concentrations and distributions of dissolved iron (dFe) and manganese (dMn) in the surface waters of the Laptev and East Siberian Seas (LESS) during the late summer of 2021. The study concludes that the concentrations of dFe and dMn in the LESS are primarily controlled by river discharge and shelf sediment inputs rather than by sea ice melt. The manuscript contributes important data to the relatively understudied area of trace metal dynamics in the Arctic. The descriptions of sampling and analyzing methods are solid. While this manuscript leans more toward descriptive analysis, it still offers valuable insights into the region's biogeochemical processes. I have several comments on this manuscript:

Major Comments:

Revise the Abstract: The abstract lacks clarity and does not efficiently summarize the entire article. The wording is awkward in places, such as in the phrase "Nutrient-rich Pacific-sourced water exists...," which does not clearly convey that this water mass is dominant in the region. The conclusion section is clearer and does a better job of summarizing the findings. Please rewrite or revise the abstract for better clarity and conciseness.
Reorganize the structure. The method for calculating water mass fractions, described in lines 181–210, should be moved to Section 2 (Methods)
Lines 211–220 do not present the mass fraction of Atlantic water. This information should be included. And its also not shown in Figure 3.
Section 4.2.1: The sedimentary contribution to dFe and dMn is not adequately discussed.
Line 334–335: This section is unclear. Although sedimentary inputs to dFe and dMn were discussed in Section 4.2.1, the correlations between TdFe, TdMn, dFe, and dMn should be more clearly explained.
Figure 6 and Line 297: What are the possible explanations for the outliers with high TdFe and TdMn? Are these stations heavily influenced by sedimentary inputs? Please address these points.
Section 4.4 and Figure 11: The comparison with other studies is valuable, but Figure 11 caption is not informative enough and needs to be modified. Please properly cite data sources in the figure captions. Use different symbols for different data sources instead of the same symbols, and highlight the data from this study using distinct symbols. Additionally, I suggest adding a summary figure by region to show how the data from this study compares with or complements the range of data reported in previous research.
Minor Comments:

Considering color figure 2 by the δ¹⁸O values and using different symbols to distinguish the different ice stations.
The differences between total dissolved iron (TdFe) and total dissolved manganese (TdMn) should be clearly defined in the methods section. A detailed explanation is not provided until line 184. It should be clarified that total dissolved Fe includes both dissolved and particulate Fe in the water column.
Line 257–260: The phrase "deviated towards" is confusing in this context. The surface water is not close to the meteoric δ¹⁸O values, although the salinity is close. It seems you might mean "deviated from" instead. Please revise this sentence for clarity.
Definition of fmw: On line 306, clarify that fmw includes river runoff and local precipitation in the calculation of water mass fractions. (Please refer to Major Comment 3)
Figure 7b and Line 319: I am curious about the r and p values for AMW and PMW separately. Please include these in the figure, as you have done in Figure 7a, even if they are not statistically significant.
Figure 10b: Please report the r and p values in Figure 10b, as you did in Figure 10a, even though the correlations are not statistically significant.

Sincerely
Dr. Edem Mahu
Handling Editor

The authors have thoroughly addressed all comments raised by the two reviewers, and the manuscript is in good shape for publishing.