In the manuscript „Spatial and seasonal variability in volatile organic sulfur compounds in seawater and overlying atmosphere of the Bohai and Yellow Seas” Yu et al., compare surface measurements and depth profiles of marine OCS, DMS and CS2 in two different seasons (spring and summer). Accompanied by ancillary data (ocean temperature, salinity, chla, nitrate, DOC) the authors try to interpret their data related to production and loss processes of each sulfur compound. Finally, using also atmospheric OCS, DMS and CS2 measurements they calculate the sea-to-air-flux of the described sulfur compounds.

Measurements of sulfur compounds in the ocean and atmosphere are scarce (especially CS2 and OCS in comparison to DMS), but they are urgently needed to investigate their influence on a global scale. Therefore, this dataset is a valuable contribution to increase the number of measurements during different seasons in this specific marginal sea area. However, the scientific content of the manuscript remains pretty descriptive. The discussion part seems very comprehensive but at the same time stays superficial. The introduction part ends with “…we investigate…variability of COS, DMS, and CS2…to better understand production and loss processes of VSCs”. Here, I strongly disagree. The authors know and also mention in the introduction the different parameters (e.g. CDOM, DMSP, bacteria) which influence (photochemical or biological) production and loss of the presented sulfur compounds but this ancillary data is not presented here. I suggest to revise the manuscript following the main comments below, also with respect to the english language, before publication.

General comments

Introduction

The introduction should be clearly structured. Presentation of different production and loss processes is mixed for COS, DMS and CS2. It would help the flow to clearly distinguish between these three compounds and their production/loss processes.

Material and Methods

The sampling/measurement procedure of the ancillary data (section 2.4) should be presented in a bit more detail. Also, phosphate and silicate measurements are missing in this section, although data is presented in Table S3 and Table S4.

Discussion

The authors explain parts of their results and also relate their results to other findings. However, some parts should go in to the introduction part as this is state-of-the-art knowledge. This would also give the introduction a more detailed content, also with respect to the findings of this study.

Oceanic COS is known to have a distinct seasonal, but also diurnal cycle due to the photochemical production. This is not at all mentioned or discussed in the manuscript, especially with respect to the different times of samplings (spring to summer but also potentially on a diurnal basis).

I was missing the main story in the discussion part. The authors relate their findings to some other studies in the same area also with respect to different seasons which is good and valuable. However, what is about the bigger picture or how can the results from the YS and BS be referred to other marginal seas? The authors highlight the influence of oceanic sulfur emissions on the atmospheric chemistry. How strong are emissions of those compounds compared to other regions and on global scale? The authors state in the conclusion “marginal seas…make a considerable contribution to the global sulfur budget” but miss to discuss and prove this with actual numbers. The DMS climatology from Hulswar et al. (2022) (not even cited) or a compilation of CS2 and COS measurements by Lennartz et al. (2020) could help as a start to discuss the findings in a global context.

Specific comments

ll.39: “Some researches indicates that the ocean is the source of VSCs. Opposite results also were reported that the ocean is the sink of VSCs.” I do not think that this is true for DMS and CS2. In case the authors relate this to COS (as the citation suggests), please revise this sentence to make it COS specific.

ll.57: “The production and loss of VSCs involves in phytoplankton and bacteria synthesis, zooplankton grazing, bacterial degradation, sea-air diffusion, photo-oxidation and/or photochemical reaction“. This is a very general sentence. Please be more precise with respect to the different compounds presented in the manuscript.

ll.68: “In this study, we investigate… the effects of YSCWM on VSCs distributions to better understand the production and loss processes of VSCs.” As already mentioned I think this sentence is too ambitious with respect to the dataset.

l.98: “Based on the similarities…” I guess the authors want to say that they calculated the concentrations with help of a calibration using standard gases?

l.110: “ The detection limit of the method for VSCs was 2.5-3.5 ng…” According to section 2.2 the authors used 30mL of sample to measure COS, DMS and CS2 in seawater. Using this volume and a detection limit of 2.5ng would result in a detection limit concentration of ~1.3nmol/L. However, most of the presented DMS data and all of the presented CS2 and COS data falls below this threshold. Please check.

ll.120: “...and selected ion monitoring mode (SIM).” What masses did the authors use for qualification and quantification of the different compounds?

ll.161: “The distribution of CS2…(Fig. 2)…was similar with that of DOC.” I do not see that.

l.169: ”...which may have been due to the abundance of nutrients…” Please also show nitrate in both summer and spring figures and not only in the supplement.

ll.201: “However, in the bottom waters of station H16, COS had a relatively high concentration (Fig. 5).” What means relatively? Please be precise with respect to the actual concentration or with respect to the sampling location the authors compare to.

ll.202: “The mean concentrations of Chl a, COS, DMS, and CS2 at different depths were … higher in summer than spring.” It is not clear by “different depths” what numbers are related to each other.

Section 3.3.3: The title is misleading and results shown in this section should be moved to section 3.3.1 and section 3.3.2 to add more content to the respective sections.

l.219 and Fig S2: “ According to 72h backward trajectory…”. Is there a reason why the authors started the trajectories at 500m, 1000m, and 1500m height? Do the authors have information about the marine boundary layer height? Otherwise I would suggest to start these trajectories at a much lower height in relation to the height of the actual measurements.

ll.220: “The lowest atmospheric DMS concentration appeared at station B47 (Fig. 6a), probably due to the low DMS concentration in seawater (0.5 nmol L-1).” I was wondering, why the authors only check the backward trajectories once for a single station and not for the whole area? Especially as B49 (backward trajectory provided, high atm DMS) and B47 (no backward trajectory provided, low atm DMS) are very close to each other.

l.230: “P>0.05” should be “P<0.05”.

section 3.4: Please structure this section logically.

ll.300: “In this study, the concentrations of the three VSCs in seawater during summer were higher than those in spring, which may be due to the higher Chl a in summer than in spring .” As already outlined in the manuscript, the three VSCs have different sources. Therefore, high chla as a general reason, seems a bit misleading.

ll.370: “Wind speed was the main influencing factor…” Did the authors do any statistical analysis?

Figure 1: Only YSCWM is mentioned in the manuscript. To increase readability of the figure please delete all other current names.

Figure 6: Stations are presented in alphabetical order. However, in the manuscript, atmospheric measurements are often related to inshore or offshore locations. It would be great if this information could also be part of this figure for a better comparison and interpretation of the data. Both subplots next to each other and on the same y scale would improve comparability between spring and summer.

Figure 7 and 8: There are much more datapoints for the fluxes than atmospheric measurements? How is this possible? Are there atmospheric measurements missing in Figure 6?

TableS2: Please add references to temperature dependent Henry constants.

References

Hulswar, S., Simó, R., Galí, M., Bell, T. G., Lana, A., Inamdar, S., Halloran, P. R., Manville, G., and Mahajan, A. S.: Third revision of the global surface seawater dimethyl sulfide climatology (DMS-Rev3), Earth Syst. Sci. Data, 14, 2963–2987, https://doi.org/10.5194/essd-14-2963-2022, 2022.

Lennartz, S. T., Marandino, C. A., von Hobe, M., Andreae, M. O., Aranami, K., Atlas, E., Berkelhammer, M., Bingemer, H., Booge, D., Cutter, G., Cortes, P., Kremser, S., Law, C. S., Marriner, A., Simó, R., Quack, B., Uher, G., Xie, H., and Xu, X.: Marine carbonyl sulfide (OCS) and carbon disulfide (CS₂): a compilation of measurements in seawater and the marine boundary layer, Earth Syst. Sci. Data, 12, 591–609, https://doi.org/10.5194/essd-12-591-2020, 2020.

This manuscript is the second from these exact set of cruises to the Yellow and Bohai Seas, by the same authors. Here we are shown the methods for observing COS, CS2, and DMS (DMS is also in the other publication submitted to JGR) and their distributions (horizontal and vertical). Air and water values of the gases were measured and air-sea fluxes computed. Certain factors deemed relevant are correlated with the measured values to understand sources and sinks of these gases in the air and water.  This manuscript requires a major overhaul before it can be published. The English needs to be thoroughly revised and the main ideas need to be clearer. What are the major findings from this work? Although the measurements are valuable, in order for them to be published in a scientific journal, there needs to be some insight or something new found. How does this contribution further our understanding? In addition, I am not sure if it is appropriate to publish the DMS values here without citing the other article that has been written about them (I was a reviewer of that article as well). Related to that point, other sections of the article should not be direct copies of the other manuscript submitted about this cruise (methods, etc.). Please check that.

Specific comments:

General – Did the authors measure dissolved O₂ concentrations? This would be useful information to show, especially for the depth profiles. Also, when discussing the atmospheric values, it would be more proper to call them mixing ratios and not concentrations.

Lines 54-55 - Citation formatting is awkward.

Lines 83-85 – These two sentences can be merged into one.

Section 2.2 – Why were different instruments used for the air and water measurements? The description of the atmospheric calibration is not clear, specifically regarding the primary standard. It seems like the primary standard was bought and it contained a 1 ppt mixing ratio for all three gases. Is this 1 part per trillion or part per thousand. I understand ppt = part per trillion. If so, this is a very low standard. It would also be nice to see some of the data from the calibrations, and perhaps some schematics of how the instruments were set up, in the supplemental material.

Section 3.3.3 – There is discussion of atmospheric sources here and some use of back trajectories (supplemental material), but I do not understand why only one station was examined in this way. I think back trajectories from various parts of the cruise track would be extremely useful. The atmospheric lifetimes of the gases are very different, so the back trajectories over multiple timescales for the various regions could tell a different story for each gas.

Section 3.4 and supplemental tables – There is no good explanation in the subsequent discussion (section 4) about why the correlations between the different factors change so much, especially between variables such as COS and DOC in seawater.

Section 4.1.1 – This seems like a random assortment of statements. What are the main ideas of each paragraph? I had a hard time finding the clear points here.

Section 4.1.2 – I again do not understand the point of this section. What is new? The information cited is very old. Yes, COS and CS2 processes depend on light. What is added here? Also, the statements at the end of the paragraph about sulfur in the deeper sea cannot be substantiated, as no dissolved oxygen measurements are presented. Finally, the Lennartz et al. ESSD database paper is cited, but was it used in any way to put the measurements in some context? The data presented in this manuscript should also be submitted to that database. This would be a wonderful way to use this data (for COS, CS2, air and water). There was a follow-on paper in ESSD (Lennartz et al., 2021) that looked more deeply into modelling gas exchange and a separate Lennartz et al. (2019) publication on oceanic processes. These might be useful to consider as well.

Section 4.2 – Every possible explanation is given for the atmospheric distributions. Again, what are the findings here and the main idea of each paragraph? The discussion of the DMS values in the air need more explanation (especially related to the anthropogenic source). First of all, the atmospheric lifetime of DMS is on the order of 1 day. Therefore, 72-hour back trajectories are not appropriate. If there is a relevant anthropogenic DMS source, it needs to be stated and cited.

Supplemental material – The figures are cited out of order in the main text. Using a compromise to provide the same scale for the two plots in figure S1 might make the information more attainable. Table S2 should have references to the work providing the constants. Why are tables S3 and S4 in the supplements and not the main text? They seem like key components of the discussion.

References

Lennartz, S. T., Gauss, M., von Hobe, M., and Marandino, C. A.: Monthly resolved modelled oceanic emissions of carbonyl sulphide and carbon disulphide for the period 2000–2019, Earth Syst. Sci. Data, 13, 2095–2110, https://doi.org/10.5194/essd-13-2095-2021, 2021.

Lennartz, S. T., von Hobe, M., Booge, D., Bittig, H., Fischer, T., Goncalves-Araujo, R., Ksionzek, K. B., Koch, B. P., Bracher, A., Röttgers, R., Quack, B., and Marandino, C. A.: The influence of dissolved organic matter on the marine production of carbonyl sulfide (OCS) and carbon disulfide (CS2) in the Peruvian upwelling. Ocean Science, 15, 1071-1090. DOI 10.5194/os-15-1071-2019. 2019.