Accumulation of Potentially Toxic Metals in Egyptian Alluvial Soils, Berseem Clover (Trifolium alexandrinum L.), and Groundwater after Long-Term Wastewater Irrigation

Round 1

Reviewer 1 Report

The text on heavy metals accumulation in an irrigated area of southern Egypt is based on samples of soils, groundwater and a commonly cultivated plant; altogether, the amount of samples exceeds 100 with a number of subsamples giving quite a lot data to draw reasonable conclusions having potential to be interesting for international audience; for this reason the materials seems to be almost sufficient for the text however, I would strongly recommend to follow up with sampling of natural unpolluted sandy sediments (only several samples would be enough) for establishing local geochemical background for comparisons of the obtained concentrations. The element orders (or sequences) used commonly throughout the text are wrongly termed “trends” or “accumulation trend” whereas, they can be used rather informally than as a basing tool of the analyze  - it is more reasonable to compare enrichment factors of elements (just basing on local background) because variable Clark`s values of the elements.

Overall, the text gives very detailed and lengthy description of the data presented mainly in tables which, combined with the discussion, makes the text difficult to read and follow. At the moment it is difficult to find what authors really wants to say and prove in the text because it is not clearly focused on the long term effects (which are interesting itself) of wastewater treatment (defined in the goal). Generally, the investigated material is only weakly (or moderately in case of some elements) polluted what is seen even at the first glance and this can be described more concisely. To improve the style of the R&D section it should be split into two separate parts where research will be presented in parts : groundwater contamination, soil contamination (e.g. now are 2 sections 3.2 HM concentrations in soils and 3.4 soil contamination by HM which should be merged) and plant contamination – all can be  shorten by ca. 1/3. The separate discussion section should be clear and focused on the defined goal, discussing only findings of the present study (on metal contamination effects of irrigation also in international context) but not mixed with facts from earlier own studies in the present manner (but they can be used for explanations).  Give suggestions and evidences of source of Cu and Pb in irrigation water. You should also not analyze insignificant data (most given in the Table 4) or writing obvious facts (e.g. l. 259 - 261) or write imprecise phrases (e.g. uniform contamination pattern l. 329 what is pattern here?); HM do not accumulate in water (groundwater). Do not use phrases: “total metal forms”, “total form”, “higher significant x concentration” or “receives contamination of this HM” (l. 243). At the end of corrections the English should be polished.                

Author Response

The studied soils are developed on the alluvial sediments of the Nile (clay and silt), where the sandy soils are far from these areas. These sandy soils are irrigated using different water supplies (groundwater) and the comparison here would be difficult.

The term "accumulation tendency" has been changed

The results and the discussion section were presented in two distinct parts (3. Results and 4. Discussion)

The results of the first studies are important when discussing the results of the work in progress. It is important to compare our results with others to explain the results.

In survey studies, sometimes, no significant results provide explanations for accepting or rejecting the hypotheses suggested in the study. Therefore, it is interesting to analyze and discuss these data

The phrase "uniform pattern of contamination" has been changed

The accumulation of metals in groundwater has been changed into groundwater contamination

The total metal form was modified based on the total metal content The sentences in line 243 have been changed

The English language has been polished as much as possible 

Reviewer 2 Report

Dear Authors,

 I would suggest that the following comments be considered beforehand.

Specific comments

Please include specific and quantitative results in your abstract, while ensuring that it is suitable for a broad audience.

The clarity of graphics (and especially of Figure 1) should be improved.

Lines 173-204. The structure of Chapter 2.4. is not typical of scientific papers (around a few subsections, some of which contain no more than 2–3 sentences).

Although the term “heavy metal” is not incorrect, it has been called a "misinterpretation" in an IUPAC technical report due to the contradictory definitions and its lack of a "coherent scientific basis". There is an alternative term, “toxic metal”, which the authors could adopt throughout their manuscript, thus maintaining consistency and avoiding interchanges.

It might be useful to divide the article into distinct parts, i.e. study results and a discussion of study results including a precise analysis of cause and effect.

Please include specific and quantitative results in conclusions.

Comments for author File: Comments.pdf

Author Response

Specific and quantitative results were included in the abstract section

The clarity of the figures has been improved

The term "heavy metals" has been replaced by the term "potentially toxic metals"

The results the results and discussion was divided into two distinct parts, namely 3. Results and 4. discussion

Specific and quantitative results were included in the section with conclusions 

Round 2

Reviewer 1 Report

Suggestions of minor corrections in the file attached

Comments for author File: Comments.pdf

Author Response

Dear, I thank you for the correct and precise comments that I have accepted and allow a better understanding of the paper.