Influence of NOM on the Stability of Zinc Oxide Nanoparticles in Ecotoxicity Tests
, Geunbae Kim 1 and Pilje Kim 1,*Round 1
Reviewer 1 Report
You miss the statement that your animal experiment was approved - at least I could not find it. Therefore your manuscript cannot be accepted for publication.
You need a native speaker with scientific understanding of your topic to correct your manuscript. It is an accumulation of half-correct or nonsense sentences that make little sense when carefully reading. - You are almost there with the sentences but then one word makes some of them absurd and/or incorrect. e.g. the Zn-ion concentration was measured by a centrifuge and ICP-MS...
You need proper references in the beginning of your Intro. The table cannot be part of the Intro and you should add the information on the free ions measured in the experiments.
In your preparation of solutions you need to report applied Joule.
Author Response
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Reviewer 2 Report
This manuscript investigated the mitigation effect by NOM on acute toxicity of Zn MNs. The chemical and physical properties were well analyzed by many parameters, the discussion integrating these results and acute toxicity (especially the cause of toxicity decrease by NOM) was not enough for publication. Most of the finding of the chemical and physical properties are already known by the previous literature; therefore, a new finding by this study is hardly observed. If you add enough discussion on the reason of NOM effect on Zn MNs toxicity, the manuscript may be re-considered for publication.
The detailed comments are as given below.
Introduction:
L.31-44: There are no reference literatures cited in first 3 paragraphs. Please cite appropriate literatures.
L.51-54: Prior to publication of TG318, validation tests should have done. Have you checked such a validation tests or the reference cited in TG318? If so, please describe what additionally need to be validated.
Table 1 Please describe Table 1 in Introduction part to summarize the previous studies. Endpoint means a kind of parameter of toxicity, so if you show the exact values of LC50/EC50, Table items should be revised: e.g. “toxicity values” or “endpoints and effect”.
L.151 TG20122, 20223, 20324→TG201, 202, 203?
L.151 purified water→purified tap water? How to purify the tap water?
L.191 8 test species→8 fish (to avoid misunderstanding)
The water temperature should not differ by more than 2°C between test vessels or between successive days at any time during the exposure, and should be within the temperature ranges specified for the test species. Please describe the actual setting temperature and temperature change (within ±2℃).
L.195-196 This sentence concerns all ecotoxicity tests, so should be moved to a new section (e.g. 2.5.5 Statistical analysis) or moved to each section (to avoid duplicate description, once you cite the Probit Analysis Program, you can omit the description, e.g. (fish) LC50 was calculated using probit analysis [29]
Figure 7 Inhibitory rate→”Growth rate inhibition” or “Growth inhibition”
L.286-309 & Figure 6 Could you scale up the y-axis to get closer and compare the samples? How about the concentration filtered by 3kDA w/o NOM? Did you perform this analysis for only one concentration (i.e. 2 mg/L at initiation)? Why the detection limit was so high (2 mg/L) even if you used ICP-MS? Since EC50 of Zn (ion) for P. subcapitata and D. magna is around 60-100 µg/L and 400-1000 µg/L (dependent on water hardness), respectively, you should measure at more low concentration for all test concentration in the ecotoxicity test and re-calculate EC50 based on ion concentration to investigate whether the decrease of ion concentration by NOM affected the toxicity.
L.304 toxicity of NOM→toxicity of Zn with NOM.
L.304-309 This paragraph is recommended be moved after ecotoxicity test results.
L.343 Please add the discussion for the reasons of controversy results with the previous study [19].
Figure 8 Please add the plots for concentrations greater than 76.9 mg/L and all concentrations with NOM (mortality=0%).
Author Response
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Reviewer 3 Report
The manuscript investigates the influence of natural organic matters (NOM) on the stability of zinc oxide nanoparticles in ecotoxicity tests. For accurate toxicity studies, it is necessary to conduct a test using NOM as an additional dispersant that strengthens stability with increased repulsive force. Authors used three types of ecotoxicitytests based on the dispersion stability test using NOM. They showed that the toxicities of the test samples were found to decrease in the presence of NOM. Additionally, although NOM used in the test is considered to be a proper dispersive substance that does not have a toxicological effect on aquatic organisms, the presence of NOM resulted in reduced toxicities and should be further investigated to establish it as a standard test method.
The work is original, interesting, and professionally carried out, showing well thought out experimental design as well as scientific insights. The manuscript is also clearly written, but I don't feel qualified to judge about the English language and style.
The subject of the manuscript is consistent with the scope of the "Applied Sciences". I have no reservations and I recommend publication of the work.
Author Response
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Round 2
Reviewer 1 Report
Thanks for the explanations.
Author Response
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