Accumulation of Different Metals in Tomato (Lycopersicon esculentum L.) Fruits Irrigated with Wastewater

Reviewer’s comments

Author’s response

Reviewer 1

The corrections done in response to reviewer 1 are highlighted in yellow text

Thank you very much authors for you paper submission in this journal. Topic is interesting and important in the field of food consumption. However article need improvements.

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1. The English language is poor and need a lot of improvement.

The document is carefully checked for English language and grammar

2. The details of atomic absorption (AAS) studies should be added in the manuscript.

Added

3. Line 79, 136, the English letters in the second cation should be in small letters.

Corrected

4. The toxicity limits of present studies must be compared with previous studies in the tomato and what are there permissible limits with suitable recent literature.

The latest permissible limits according to the Indian standards and European legislation limit are added to Table 2

5. The references are in large numbers. Reduce the references up to 55-60.

The number of citations is now reduced to 60

6. The reference style must be checked and according to the journal.

We have formatted this paper with MDPI Endnote style available at website

Reviewer Comments

Author’s response

1, Line 133, “concentrations of K2PO4…” Should be K2HPO4

Corrected

2, Line 165-166, “In contrast, no significant difference was found in stem and leaf Na contents where 34% increase in Na over control was recorded.” What has “no significant difference”?

Corrected to non-significant

3, Section 3.2

When talking about metals or nutrients concentrations are higher in the samples from the wastewater irrigated soil than those from the control water irrigated samples, authors claim they “accumulated” more due to higher wastewater concentration. This is under the assumption that the background concentrations before the irrigation in the wastewater irrigated field soil and the control water irrigated field soil are the same. However, no background concentrations are provided. Author may overstate the observation. This comment is also related to comment #10.

The contradictory statement is deleted

 4, Line 166, 174, 189, 203, “The decreasing order of K accumulation in edible and non-edible parts of plants …”

The related figures all have concentration order. Not look like “accumulation” order. A few other locations in the paper have the same issue.

Corrected at all places to “concentration”

 5, Table 1 and Figure 1

What is the unit for the numbers for soil? In mg/L? What about the unit for the “permissible limit”? Soil concentration should use mg/kg of dry weight as unit. If using mg/L for soil concentration, then this concentration is depending on the water added into the soil sample and the amount of soil used.

Corrected unit of metal concentration in soil to mg kg^-1

 6, Figure 1

The wastewater and control water only were sampled once?  How much change the wastewater and control water metal and nutrient concentration during the irrigation period (with tomato)? Does the change have any impact on the results?

This information is added to the Materials and Methods

 The metals and nutrients have significantly different concentrations in the wastewater and the control water and in the corresponding soil samples too. If looking at the concentration ratios between the soil vs. the water, is there any significant difference between the wastewater and control water irrigated field?

We have used a different approach using multivariate analysis like heatmap and PCA to draw conclusions between absolute values in plant organs and those metal concentrations within water and soil

7, All figures, “*, **, ** = significant at 0.05, 0.01 and 0.001 levels”.  Should be: *, **, ***

Corrected

 8, Line 209, “The order of metal accumulation in both soil and plant was Fe>Pb> Zn>Mn” This is concentration order not accumulation order. The accumulation should be the concentration ratios between the soil and the water.

Corrected to “Concentration”

9, Figure 4,

What is the reason behind the results (no significant difference) in Endocarp for Fe and Mn even Fe and Mn have very different water and soil concentration?

Fe and Mn and immobile in plants. As seen in our results, these metals were mostly sequestered in roots and due to little mobility, caused non-significant differences in Endocarp. This is also added to the discussion

10, Figure 2,3,4, and 5

Authors plotted the concentration in tomato plant parts and compared the concentration in control and wastewater irrigated field. Why the authors not plot ratio between the concentration in the plant part vs the concentrations in the soil for control and the wastewater irrigated field? If this ratio is plotted, is it possible that the ratio is higher in the control than in the control? If yes, does this has any impact on the conclusion of this paper? Does this ratio give authors a different view on the study?

We have used absolute values to plot the data. We have tried plotting the ratios a suggested but in many cases it does not makes any significant impact on the conclusion part. Rather we have used a different approach using multivariate analysis like heatmap and PCA to draw conclusions between absolute values in plant organs and those metal concentrations within water and soil

Reviewer Comments

The changes suggested by reviewer 3 are highlighted in Bright Green color

In the manuscript applsci-2513079, the authors assessed the accumulation and distribution of nine metals in tomatoes grown with wastewater. Also, soil and wastewater were analyzed as well. The results showed there is a health impact of consuming these tomatoes.

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1. The abstract section should be rewritten based on obtained results.

Numerical values are added to the abstract as suggested

2. Introduction: There must be one section about the health impact of these metals on human beings.

A new paragraph is added to the Introduction section as suggested

3. Deep discussion must be associated with the found results. The authors only reported what they found without explanations.

The other reviewers did not suggested to make such change in discussion. However, we have rearranged discussion with subsections for better understanding in accordance with comment 4 of Reviewer 3.

Why one element is higher than another?!

Several metals i.e. Zn, Mn and Pb were higher in tomato fruits. This has already been highlighted at places in this manuscript

4. The discussion section is so long. It is better to sub-divided into sub-sections according to the samples.

The discussion is split into subsections as suggested

5. The conclusion must be supported with data

The numerical data is added to the conclusion as suggested

Reviewer Comments

CAuthor’s response

The manuscript entitled " Accumulation of different metals in tomato (Lycopersicon esculentum L.) fruits irrigated with wastewater" by Tabassam et al. described their research findings on the accumulation and distribution of metals in tomato fruits grown with wastewater. The result would be an alert for the local people in Faisalabad, Pakistan.

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The authors have done only one test with atomic absorption spectrometry in plants, water, and soil. The authors mentioned several metals in the abstract but did not analyze them all, for example, chromium. Several other metals could be of interest in their study.

Chromium is deleted from abstract

In addition, the research done by the authors is very basic. There are many articles have already been published determining heavy metals in tomatoes. There is no novelty in this study. Therefore, I believe this manuscript is unsuitable for publication in applied sciences. 

This study has already been concluded and it is not possible to add any more data to this study.