Physiological Response of Two Typical Plant Species under Combined Pb and Cd Stress in Bioretention Facilities

Round 1

Reviewer 1 Report

Comments for author File: Comments.docx

Author Response

Thanks for the reviewer's comments, the comments have helped us to further improve the manuscript and are of great importance to our research. Because of the length of the response, we present them as an attachment. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

This is a well written MS that clearly explains the experiment and the results. Its strength is the simulation of metal contaminated run-off to expose two species of importance in the urban environment and that a number of variables were measured.  The results are not surprising but are useful to see published.  The exposure time is relatively short and the replication of treatments low in number, which is perhaps related to the lack of a really clear outcome.   I think that with some amendments this paper could add some data to the literature on exposure of urban plant species to heavy metals.

I'd suggest the following amendments for clarification of methods, results and conclusions.

1. Replication. At the end of section 2.3 it's not clear to me how treatments were replicated and when SDs are given, for example in Table 1, it's not clear to me what n was and what it related to - replicate leaves from a single biological replicate or leaves from biological replicates? Related to this it would be useful to know what arrangement the trees and treatments had during growth. The photograph suggests the species were in lines - perhaps because it's a snap shot.   I'm guessing that there was a single plant for each treatment and that the SDs in table 1 were of measurements of replicate leaves - but I shouldn't have to guess, replication (or not) should be explicit and then the results interpreted accordingly.  And unless there was some randomisation in position or regular moving of positioning of the trees there needs to be a caveat on any differences between species or treatments.

2. Results. I can work out the references to figures but the text error messages for each reference to Figures/Table clearly need to be sorted out. Figure 4 legend needs improvement. Are they just single measurements at each date? Needs to be clear. a nd b are of Chlorophyll concentration over time, c is of change in chlorophyll content in different treatments. Time is a continuous variable but it is plotted as a discontinuous one on the x axis  I think - the time intervals between sampling are not even? Figure 5 - Why a bar chart? It's a plot between two continuous variables so should be line graphs here I think.  What are the error bars and what is n?  Figure 6 as above for previous figures.

3. The conclusion is that the Cd and Pb were not toxic and did not lead to plant mortality - but the question was did do they 'impair plant development'.  The hypothesis and the conclusions need significant tightening. First, I don't think that the variables measured relate very well to plant development. I think they relate to physiological function or some such and that this should be the focus of the question/hypothesis. The conclusion can then be that they do affect the physiological functioning to some extent and that, under this exposure regime which is a realistic one (good!), there is no evidence that it is overall leading to toxicity and mortality. In fact, there is some evidence of the U shaped response etc...  This would, I think, provide an improved framing of the results.  And in the conclusion section it might be worth recapitulating the three findings but the description of results is fairly exhaustive anyway and the conclusions section probably just needs to overall conclusion as above.

Author Response

Thanks for the reviewer's comments, the comments have helped us to further improve the manuscript and are of great importance to our research. Because of the length of the response, we present them as an attachment. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

1) Experimental results are mixed with quotes from other people's publications, which makes it difficult to separate the results of the authors and conjectures in connection with other people's conclusions. The article needs to very clearly separate the set of results and assumptions and conclusions of the author in the "Results" section from the separate section "Discussions" and comparisons with findings in cited publications.
2) The reviewer doubts that the data with “tap water” can be used in this work for correct comparisons with experiments with lead and cadmium solutions, since the authors do not describe in the method what quality the water was in solutions and what quality the water was in solutions. "tap water" was. This is due to the well-known classical experiments of the German physiologist and cytologist Z. Strugger and other scientists with waters of different quality back in the 19th century.

The article can be accepted with a few minor changes in the text.

Author Response

Thanks for the reviewer's comments, the comments have helped us to further improve the manuscript and are of great importance to our research. Because of the length of the response, we present them as an attachment. Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

no comments.