|Review comments for manuscript |
“Particulate trace metal dynamics in response to increased CO2 and iron availability in a coastal mesocosm experiment”
Lorenzo et al.
- General comments
Authors have responded to most of my previous comments.
I have found significant improving of this manuscript, especially for presenting their results with adequate “Figures” which is more understandable for readers. However, I still found some issues for this manuscript which have to concern before publications. Please consider for following comments.
Since authors present their data with some “Figures”, it became more clearly that parts of presentation in this manuscript (MS) are overlapped to previous published paper, Segovia et al. (2017). For instance, Figure 1a, 1b and 2 are totally same figures as reported by Segovia et al. (2017). Is it really possible to publish only with the statement as “Figure reproduced with permission from Segovia et al. Mar. Ecol. Prog. Ser. 2017” in the caption? It might be better to place in “supplementary Figures”. I would like to ask about this aspect to Editor. Also, authors should make clear in MS that “what is original purpose of this MS” in introduction, “which is original findings from this MS” in “Abstract”. Original findings of this MS are not clear in the “Abstract”(see below).
Table 1 showed the result from statistically analyses of the particulate(P) trace metal (TM) data obtained from this study. This statistically analyses are one of the important points for discussion in the MS. However, the detail for the statistically analyses are not clear for reader. For instance, which “day’s” data did authors used for evaluating the difference among treatments for each P-TM (d12, d17, d21??)? Which day’s data did authors used for evaluating the time difference (is this means significant difference between d12 and d21?)? Please explain more clearly in the text (2.4 section) and in the caption of Table 1. Same for Table 3.
Line 30-38; From “Future predicted high…… future ocean dynamics.”. This sentence should be supported by results of this study which is described in the one sentence before. Author should state here “what is the original important result and major findings from this study”. Present sentence is not clear in this point. I think, main important results and findings from this study, which should be claimed in abstract, are described in line 376-404, and “conclusion”. Authors should not include speculation in the “Abstract”. The findings should strongly be supported by this study’s own results.
Line 74-86; I found that some parts of contents in this sentence are overlapped to previous sentence (line 57-71). To make more concise introduction, please compile and reconstruct these two sentences and avoid repetition.
Line 95-105; This sentence is very important for explaining the aim of this MS. In the present description, authors explain “importance of E. huxleyi bloom for biogeochemistry in the ocean”. This is the research motivation for study of Segovia et al. (2017), but this is not motivation for investigating particulate trace metals in this MS. Whereas, Authors only describe the aim of this study as “The aim of the present study was …… CO2 and Fe bioavailability.” in line 104-105. I think author should add more explanation about “why the measurement of particle trace metals and characterize the change of particle trace metals during E. huxley bloom are important?”.
Line 97; I could not find “Segovia et al., 2018” and “Lorenzo et al., 2018” in the reference list in end of MS. Please check all reference in the text and reference list in the MS.
- Material and method
Line 114, Authors described that CO2 concentration in the mesocosms were measured by NDIR analysis system. Whereas, in line 116-117, authors described that CO2 concentrations in the mesocosms were calculated from pH and alkalinity. Which is correct? According to Segovia et al.2017, “CO2 concentration in inlet flow” is only measured by NDIR.
Line 121, Why the DFB concentration was set to 70 nM? This value is important for this study because particle dissolution for some trace metal was strongly influenced by the DFB concentrations as authors described in discussion.
Line 128, “gentle vacuum pumping”. Is this pumping system clean for level of trace metal work? Detailed description is needed for explaining sampling system, cleaning procedure, because these are critical part of trace metal work.
Line 139, How did authors collect the seawater (by using pumping as described in line 128?). “0.2 uM” should be change to “0.2um”.
Line 147; “trace metal hydrochloric acid” should be “trace metal grade hydrochloric acid”.
Line 154; “0.2 uM” should be change to “0.2um”.
Line 156; Is this “centrifuge tubes” same tube as “2mL PP” tubes?? Reader will be confusing.
Line 225-249; Section 3.2, 3.3 and 3.4. Authors need to explain detail about statistically analysis for Table 1 and Table 3, see general comment.
Line 286 “well-known metal content in biogenic particles” and line 287 “normalized to Al (mol Me: mol Al in the Earth crust)”. Please indicate the number which was used for this calculation and indicate reference for the number.
Line 289; “0.0051 for mol Fe:molP”, “0.331 mol Fe : mol Al”. How did authors select this number? Which information did author refer? Maybe, “Ho et al., 2006” in Table 2 (A) for “0.0051” and Table 2 (B) for “0.331”. Table 2 (B) crustal ratios need reference (Taylor 1964?). Add ref. to “Table 2 (B)”.
Line 321; I could not find “Table 5” in MS.
Line 347; “Zn and Cu dissolution (ref.)”. Please add reference.
Line 353-355; “Rain events…… (Muller et al., 2005)”. Do authors have some information on rain event before or during the experiment? If they have, it is important additional information for this interpretation.
Line 355-358; “, and indigenous plankton……Knauer et al., 1998).”. This sentence is too speculative, and not main discussion for particulate Cu:P ratio. I feel author can delete this sentence.
Line 362, 363; I can not find “Figure 6” in the MS.
Line 376; “in that it was the only trace element whose particulate concentration significantly and uniquely affected…….”. I think this is not true. According to Table 1, other metals (Co, Zn, Cd Mn Mo) were also affected by CO2.
Line 384-387; Authors discussed about partitioning of DFe and PFe with using Figure S2. I think this results and discussion are one of very important finding of this MS. This result is base of predicting future ocean in the following discussion. I recommend that Figure S2 should be placed for the normal Figures (not in Supplementary).
Line 396; I could not find Table 5 in the MS.
Line 424; “due to increased Fe bioavailability”. How authors judged the increasing Fe bioavailability in the LC+DFB treatment? Is there any evidence which indicate that DFB-bounded Fe is available for E. huxleyi? Please discussed more carefully about the changing Fe bioavailability in “discussion”.
End of review