Ecotoxicological Effect of Aged Wood Leachates to Aquatic Organisms
Round 1
Reviewer 1 Report
The manuscript brings new and interesting data however needs improvements, for the details please see below and in attachment (supplementary part)
Language should be checked carefully, e.g. in abstract lowercase and uppercase letters; often the use of jargon can be observed, I’m not an expert but some parts of the text are difficult to read, let’s say “it is not fluent”, it can be improved in several parts of the manuscript
line 28: may cause instead of “cause” (not all adverse effects of all compounds are proven, if yes this paper will not bring a novelty
Line 32: Research had proven (rather has). This sentence (lines 34-36) should be reread and rephrased
Line 46-49: this part is unclear,in addition what does it mean: “toxicity of aquatic organisms”, ”This research was informed by report”, “This when established...”?
Materials and methods
Materials and methods not method (several methods are presented)
No information about statistics applied in interpretation of results
Line 62: – amber glass bottles?, Conditions of aging should be explained more in details
Line 67: “metals present in the wood leachates” this statement needs clarification, not all metals present in leachate were analysed, just those selected by the authors, target metals should be presented here, moreover analysis of metals: short description of method (including the steps before final AAS analysis) should be provided with appropriate references and parameters characterizing the method, ( at least LOD and precision) (all methods should be presented in supplementary materials briefly)
Line 77: A stock culture of the algae, it should be explained which species were used in the tests – it should be clearly shown in the material and methods part.
Line 84: samples were prepared to a percentage leachate concentrations – a kind o jargon
Line 90: Duckweed aquatic plant toxicity test –this subtitle can be shorter (Duckweed toxicity test or Lemna minor toxicity test)
Line 101: “chlorophyll content” It should be clarified: chlorophyll a and b ? or only chlorophyll a? It should be clear also in the other parts of the text
Line 113: “beakers filled with various concentrations rate samples” a kind o jargon
Results and discussion
Line 120 The woods understudy?
Line 122 there was changes?
line 124 ” The different colours and changes in leachate colours with age observed was due to...” I would suggest to replace “was” by can be explained by”, as the authors rely on references not own results.
Line 131 “of most of the leachate samples” change “of” to “for”
Line 147 and following - the whole discussion about metals should be refined and the metal ( and their influence on tested organisms) should be divided into two groups: those which are toxic (e.g. cadmium) and those which are essential elements (like Mn) but at high concentrations can become toxic for organisms:
Line 155 table 1 see remarks for supplementary material e.g. column heading , I would suggest to change to: “ Metal concentration (mg/L) in wood leachate sample”
From further considerations I understand that WHO limits apply to discharge limit for wastewater – it should be clearly stated maybe in materials and methods
It is unclear why the same tables appear in the main text and in supplementary material – this remark is valuable for all tables and figures appearing in both parts.
Line 172 “.....total organic carbon were determined to know the level of organic pollutants” it is a kind of a generalization, that’s true that often organic pollutants have the tendency to bind to organic matter, nevertheless the total organic carbon can not be an information about the level of organic contaminants, TOC includes natural organic compounds like humic acids, lignins etc. present in significantly higher concentrations than organic contaminants, so especially in case of wood leachate this statement must be presented with an extreme caution. An example: we can have large amounts of organic matter of natural origin (therefore high values of TOC), but organic pollutants are not present in the sample due to lack of sources, so high TOC does not mean that we have high organic pollutants concentrations. So this statement needs clarifications and rephrasing....
Line 198 “presence of more organic carbons”- jargon
Line 210 “Emire and mahogany were 33 and 66 times higher than the permissible limit” jargon
Table 7 “Total Phenol of 24 hours....” rather Total phenol concentration for 24hours .....aging period ...
Line 217 “The concentration of phenols measured in the wood samples” not wood samples but wood leachate samples
Line 222 Ecotoxicity tests instead of ecotoxicity test
Line 223 “The toxicity of the various wood leachates to algae” please explain which species
Line 251 Figure 1 again we don’t know which species of algae was/were used in the experiment, “exposure to dilution series “ of what? In the figure caption it should be clearly presented that the authors investigated the influence of wood leachates of different age” same remark for the other figures
Line 253 what does it mean “nature of colour”?
Line 263 “The absence of Zn”, the absence is unclear, that’s why I have asked to present LOD values
Line 277 “The percentage median Inhibition Concentration (%IC50) for algae toxicity” for algae toxicity – again jargon and algae species are not listed, what is really confusing
Line 293 “Usually, this increased in frond numbers” - ? English
Line 340 “Under the area inhibition curve of mahogany” jargon
Line 369 column heading “Leachate age” rather than “Age leachate”{chlo chlorophyll a?, authors are asked to replace “area” by “frond area”
Line 364 “that the leachates toxicity towards duckweed decreased as the leachates are stored”rather were stored?
Line 371 “Daphnia magna is one of the few zooplanktons” jargon
Line 372 endpoints instead of endpoint
Line 396 “in most of the leachate” rather: leachates
Line 397 starting the sentence with “because” should be avoided; dissolved oxygen concentrations instead of dissolved oxygen
Line 402 “The high BOD, COD and TOC in the leachate would have competed with the daphnia” a kind of shortcut
Line 405 chemotoxicity?
Line 428 “....but the main cause of toxicity in the various wood leachates was the high levels of phenols “ I would be not so “firm”, it needs more statistical analyses and maybe more observations , or the authors should show this evidence more clearly in results and discussion part, anyway I would suggest to change was to might be (the same remark for abstract)
Comments for author File: 
Comments.pdf
Author Response
Please see the attached response to the review comments.
Best regards
Lyndon
Author Response File: Author Response.pdf
Reviewer 2 Report
I have included my comments and suggestions in an attached file (please see below).
Comments for author File: Comments.pdf
Author Response
Please see attached the response to the review.
Best Regards
Lyndon
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Line 16 and 17 , “The toxicity in of the various wood leachates might be due to high levels of BOD, COD and TOC , metals and Phenols” change “in” to “of” and Phenols to phenols
Line 40 can be found in” not "can be in"
Line 40 and 41 wordwide is the same statement as one line above "can be found around the worls
Line 51 "Lemna minor is a small floating plant with a single root and in the genus Lemna" I would suggest to " "Lemna minor (genus Lemna) is a small floating plant with a single root"
Line 76 sentence “Even though the toxicity – something went wrong here
Line 111 and 112 “Three replicates of 15 mL control medium and the leachates percentage concentration used for the toxicity test were (20 ,30 ,45 ,67 and 100% v/v) – please check grammar correctness
Line 144 – “containing various concentrations of samples” I would suggest to add “leachate samples” to be more clear
Line 350 “(20, 30, 45, 67.100%v/v) , line 440 table 9 %IC of Lemna minor frond area and chlorophlly content(a and b) etc. please go once again through the text and correct all typo mistakes, I think it was made due to the fact that the authors had to cope with a quick reply to reviews remarks nevertheless it should be corrected before publishing
Line 423 “Daphnia magna a zooplankton was used” correct this sentence rather to “A zooplankton species Daphnia magna was used
New supplementary: I have found unnecessary to put just one sentence about LOD for metal analyses in supplementary part, this one sentence should appear in the main text (materials and methods)
Author Response
Dear reviewer,
Please find attached my response to your comments on the second round.
Best Regards
Lyndon
Author Response File: Author Response.pdf
