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Peer-Review Record

Trends of Nitrogen and Phosphorus in Surface Sediments of the Lagoons of the Northern Adriatic Sea

Water 2021, 13(20), 2914; https://doi.org/10.3390/w13202914
Reviewer 1: Anonymous
Reviewer 2: Anonymous
Water 2021, 13(20), 2914; https://doi.org/10.3390/w13202914
Received: 10 September 2021 / Revised: 8 October 2021 / Accepted: 12 October 2021 / Published: 16 October 2021
(This article belongs to the Section Water Quality and Contamination)

Round 1

Reviewer 1 Report

This article about the temporal changes in nitrogen and phosphorous concentrations in sediments in different TWS from Italy and its relationship with anthropogenic impacts it is well written, adequately explained and innovative. However, it has several formatting flaws and some methodological concepts should be better explained. For this reason, the authors should review their manuscript again make the suggested changes for the manuscript to be considered for publication in Water.

Comments and suggestions:

Title is too long. I suggest changing the title by “Trends in nitrogen and phosphorous in surface sediments in the lagoons of the northern Adriatic Sea”, or something a bit shorter.

Line 37: mostly eutrophication [3, 4, 5, 6, 7] river [8, 9] and clam harvesting?? These references are specific of studies performed in Italy and Venice. For this very general sentence in the introduction, more general references should be included, not only for studies in Italy.

Line 66-70: where are these data available in?

Line 87: use “ca.” instead of “approx.”.

Line 88: abbreviate hours as “h”, not “hrs”.

Line 99: Are these 85 stations the same as in previous years? Explain this.

Line 117: Ntot? Explain the meaning of this abbreviation as for phosphorous in lines 100-101.

Line 119: in of?, Is this a mistake? In 2.1.2 The lagoon of Marano-Grado the sampling strategy for selection of the sampling sites “evenly distributed” is mentioned. How did you choose the sampling stations in each TWS? Is the sampling strategy the same for each place? This information is missing and should be provided.

Line 130: Ruppia cirrhosa, is this a salt-marsh plant or what kind of organism is it? Please, specify this.

Line 132-133: why did you mention the specific sampling sites in Po Delta lagoons and ponds, i.e. (3 at Caleri, 2 at Marinetta, 2 at 132 Vallona, 3 at Barbamarco, 3 at Canarin, 4 at Scardovari 3 at Goro) were sediment samples were collected, buy not in the Venice lagoon for example? The description of the sites in all TWS should be the same in order to maintain coherence throughout the manuscript. The location of the sampling stations in each TWS needs to be indicated on the map or better detailed in the text.

Line 143: which stations?

Line 152: fwt means freshweight? Please, indicate the meaning of the abbreviation.

Line 155: I suggest including a section 2.2. Sediment sampling or Sampling, before the 2.3. “Nutrient determination in surface sediments” section. The text within lines 156 and 160 should be included in this section, as it is referred to sampling, not to nutrient determination itself. In this 2.2. section, the sampling sites selection, sampling strategy and sampling dates should be explained in this section, not individually in after the description of each individual TWS.

Line 187: Which software did you use for the PCA? Please, specify.

Line 217: both instead of bot.

Line 221: In Tables 1 and 2: “Temporal changes…” instead of “Changes…” should be better.

Line 225: Do not abbreviate Table, use Table 2 instead of Tab. 2. Check this throughout the manuscript.

Line 254: Add the units for nitrogen concentrations.

Line 265: r = -0.85 instead of r = -85. Besides in Table 3 that correlation is r = -0.84. Check this.

The units in the Figure 2 are not correct, they have the comma separator instead of the dot for decimals. This needs to be changed.

Sometimes you use e.g. (p<0.001), (p < 0.001) and (p < 0.001). Please use the same format for p values.

The authors should check the references in the references list because some of them do not follow the same format.

This article about the temporal changes in nitrogen and phosphorous concentrations in sediments in different TWS from Italy and its relationship with anthropogenic impacts it is well written, adequately explained and innovative. However, it has several formatting flaws and some methodological concepts should be better explained. For this reason, the authors should review their manuscript again make the suggested changes for the manuscript to be considered for publication in Water.

Comments and suggestions:

Title is too long. I suggest changing the title by “Trends in nitrogen and phosphorous in surface sediments in the lagoons of the northern Adriatic Sea”, or something a bit shorter.

Line 37: mostly eutrophication [3, 4, 5, 6, 7] river [8, 9] and clam harvesting?? These references are specific of studies performed in Italy and Venice. For this very general sentence in the introduction, more general references should be included, not only for studies in Italy.

Line 66-70: where are these data available in?

Line 87: use “ca.” instead of “approx.”.

Line 88: abbreviate hours as “h”, not “hrs”.

Line 99: Are these 85 stations the same as in previous years? Explain this.

Line 117: Ntot? Explain the meaning of this abbreviation as for phosphorous in lines 100-101.

Line 119: in of?, Is this a mistake? In 2.1.2 The lagoon of Marano-Grado the sampling strategy for selection of the sampling sites “evenly distributed” is mentioned. How did you choose the sampling stations in each TWS? Is the sampling strategy the same for each place? This information is missing and should be provided.

Line 130: Ruppia cirrhosa, is this a salt-marsh plant or what kind of organism is it? Please, specify this.

Line 132-133: why did you mention the specific sampling sites in Po Delta lagoons and ponds, i.e. (3 at Caleri, 2 at Marinetta, 2 at 132 Vallona, 3 at Barbamarco, 3 at Canarin, 4 at Scardovari 3 at Goro) were sediment samples were collected, buy not in the Venice lagoon for example? The description of the sites in all TWS should be the same in order to maintain coherence throughout the manuscript. The location of the sampling stations in each TWS needs to be indicated on the map or better detailed in the text.

Line 143: which stations?

Line 152: fwt means freshweight? Please, indicate the meaning of the abbreviation.

Line 155: I suggest including a section 2.2. Sediment sampling or Sampling, before the 2.3. “Nutrient determination in surface sediments” section. The text within lines 156 and 160 should be included in this section, as it is referred to sampling, not to nutrient determination itself. In this 2.2. section, the sampling sites selection, sampling strategy and sampling dates should be explained in this section, not individually in after the description of each individual TWS.

Line 187: Which software did you use for the PCA? Please, specify.

Line 217: both instead of bot.

Line 221: In Tables 1 and 2: “Temporal changes…” instead of “Changes…” should be better.

Line 225: Do not abbreviate Table, use Table 2 instead of Tab. 2. Check this throughout the manuscript.

Line 254: Add the units for nitrogen concentrations.

Line 265: r = -0.85 instead of r = -85. Besides in Table 3 that correlation is r = -0.84. Check this.

The units in the Figure 2 are not correct, they have the comma separator instead of the dot for decimals. This needs to be changed.

Sometimes you use e.g. (p<0.001), (p < 0.001) and (p < 0.001). Please use the same format for p values.

The authors should check the references in the references list because some of them do not follow the same format.

Author Response

Dear reviewer

We have appreciated the comments and suggestions that helped to improve the paper and have integrated the text accordingly. All adjustments, integrations and new references are in red.

Comments and suggestions:

Title is too long. I suggest changing the title by “Trends in nitrogen and phosphorous in surface sediments in the lagoons of the northern Adriatic Sea”, or something a bit shorter.

We have changed the title accordingly.

Line 37: mostly eutrophication [3, 4, 5, 6, 7] river [8, 9] and clam harvesting?? These references are specific of studies performed in Italy and Venice. For this very general sentence in the introduction, more general references should be included, not only for studies in Italy.

We have added many other international references both in the introduction and in the discussion

Line 66-70: where are these data available in?

They are data collected by our research team  and published on:

Sfriso, A.; Facca, C.; Bon, D.; Giovannone, F.; Buosi, A. Using phytoplankton and macrophytes to assess the trophic and ecological status of some Italian transitional systems. Cont. Shelf Res. 2014,  81, 88-98.                                                               

Line 87: use “ca.” instead of “approx.”.

We have changed this term

Line 88: abbreviate hours as “h”, not “hrs”.

It was done

Line 99: Are these 85 stations the same as in previous years? Explain this.

The text was changed and in the paper we have inserted the results of all the sampling stations. 165 in 2003, 118 in 2011 and 85 in 2014 and 2018.

Line 117: Ntot? Explain the meaning of this abbreviation as for phosphorous in lines 100-101.

It was explained

Line 119: in of?, Is this a mistake? In 2.1.2 The lagoon of Marano-Grado the sampling strategy for selection of the sampling sites “evenly distributed” is mentioned. How did you choose the sampling stations in each TWS? Is the sampling strategy the same for each place? This information is missing and should be provided.

Yes it was a mistake. “of” was deleted. Information on the station choose were inserted in the text. “The station sampled in 2003 in the Venice lagoon were selected to study the biomass distribution [4]. All the stations sampled in the Venice lagoon since 2011  and the stations sampled in the other lagoons  were selected by the Italian Regional Agencies for Environmental Prevention and Protection. Sampling was carried out to determine the ecological status of transitional water systems (TWS) in the framework of the European Water Framework Directive 2000/60/EC by using the biological element”Macrophytes”. In this occasion our research group collected also surface sediments to study some sediment characteristics and nutrient concentrations”.

Line 130: Ruppia cirrhosa, is this a salt-marsh plant or what kind of organism is it? Please, specify this.

We have inserted an explanation on the text. “Populations of the aquatic angiosperm Ruppia cirrhosa (Petagna) Grande……….”

Line 132-133: why did you mention the specific sampling sites in Po Delta lagoons and ponds, i.e. (3 at Caleri, 2 at Marinetta, 2 at 132 Vallona, 3 at Barbamarco, 3 at Canarin, 4 at Scardovari 3 at Goro) were sediment samples were collected, but not in the Venice lagoon for example? The description of the sites in all TWS should be the same in order to maintain coherence throughout the manuscript. The location of the sampling stations in each TWS needs to be indicated on the map or better detailed in the text.

In the Venice lagoon there are 165 (2003) 118 (2011) and 85 (2014-2018) sites equally distributed throughout the lagoon and we do not believe it makes sense to mention them or even report them on a map. The same for the Grad-Marano lagoon. Instead, we have reported the name of the stations sampled in the other smaller TWS

Line 143: which stations?

We have inserted the name of the stations. “Samples for nutrient analyses in surface sediments were collected in two stations named Donna Bona and Dosso Pugnalino placed in the main basin during late spring-early summer 2009”

Line 152: fwt means fresh weight? Please, indicate the meaning of the abbreviation.

We have inserted the meaning of this abbreviation “….with a biomass of 5-10 kg m-2 on a fresh weight (fwt) basis”.    

Line 155: I suggest including a section 2.2. Sediment sampling or Sampling, before the 2.3. “Nutrient determination in surface sediments” section. The text within lines 156 and 160 should be included in this section, as it is referred to sampling, not to nutrient determination itself. In this 2.2. section, the sampling sites selection, sampling strategy and sampling dates should be explained in this section, not individually in after the description of each individual TWS.

It was done

2.2. Sediment sampling

At each station three subsamples of surface sediments (5 cm top layer) were sampled by a Plexiglas corer (i.d. 10 cm) and mixed together. One subsample (ca. 100 ml) was retained for nutrient (total nitrogen, total phosphorus, inorganic phosphorus, organic phosphorus) analyses and another (ca. 50 ml) for the determination of the sediment density and grain-size. Both subsamples were stored at -20 °C until the laboratory analyses.

Line 187: Which software did you use for the PCA? Please, specify.

We have inserted this information “The Principal Component Analysis (PCA) determined using the STATISTICA software, Release 10 (StatSoft Inc., Tulsa, USA)…”

Line 217: both instead of bot.

Yes it was a refuse.

Line 221: In Tables 1 and 2: “Temporal changes…” instead of “Changes…” should be better.

It was inserted

Line 225: Do not abbreviate Table, use Table 2 instead of Tab. 2. Check this throughout the manuscript.

It was done

Line 254: Add the units for nitrogen concentrations.

It was done

Line 265: r = -0.85 instead of r = -85. Besides in Table 3 that correlation is r = -0.84. Check this.

It was corrected

The units in the Figure 2 are not correct, they have the comma separator instead of the dot for decimals. This needs to be changed.

It was corrected

Sometimes you use e.g. (p<0.001), (p < 0.001) and (p < 0.001). Please use the same format for p values.

The same format was used in the whole text

The authors should check the references in the references list because some of them do not follow the same format.

All references were revised

This article about the temporal changes in nitrogen and phosphorous concentrations in sediments in different TWS from Italy and its relationship with anthropogenic impacts it is well written, adequately explained and innovative. However, it has several formatting flaws and some methodological concepts should be better explained. For this reason, the authors should review their manuscript again make the suggested changes for the manuscript to be considered for publication in Water.

All the text was revised taking into consideration the reviewer comments and suggestions.

I hope I have satisfied your comments 

 Best tregards

Adriano Sfriso

Reviewer 2 Report

Dear Authors

I have gone through the manuscript titled "Nitrogen and Phosphorus trends in surface sediments, a litmus paper of anthropogenic impacts. The lagoons of the northern Adriatic Sea as a study case". In my opinion paper content fall within the range of aims and scopes of the Water journal; authors have been successful in reaching their goals, figures and tables are appropriate. However, in my opinion, the manuscript needs for some adjustment. Detailed remarks and propositions are given below.

GENERAL REMARKS

I propose to apply subscript in such terms as Ntot, Pinorg, Porg etc. to make it more clear.

Carefuly check the final version of the text, as some small mistakes and misprinting may be found.

Please make sure that numbers and units are on the same line in the text (e.g. lines 110-111: 65 cm; lines 146-147: 11 km2).

INTRODUCTION

This section is a bit too local. As you fairly noticed, nutrients may be treated as litmus paper of anthropogenic impacts and that is universal for many environments. Then, please put some more general information / background, regarding also other regions worldwide. The only “general” part of “Introduction” is the first paragraph, while others refer mainly to Venice lagoon. This “indigenousness” is also reflected in references, which are mainly Italian. It is not incorrect of course but looks a bit peculiarly and reduces scientific value of the paper. Moreover some information included in this section fit better to “Discussion” and may / should be relocated into this section.

Lines 66-70: You give some information about data for particular regions of Adriatic Sea, however it is not clear if you mean your data (discussed further in the paper) or some literature data. Please specify and put appropriate references, if applicable.   

MATERIALS AND METHODS

Figure 1 – figure shouldn’t be placed just below the title of a subsection. It should be preceded by some text. Moreover it should be located after (not before) its first citation.

Lines 100-107: consider replacing [] by () while given a year(s), as [] are used for citation of references.

Methods are described quite briefly. Please add more details or refer to the literature. (Applies mainly to section 2.2.)

RESULTS and DISCUSSION

I propose to combine and reorganize those two sections, as some paragraphs of “Results” have a discussion character (e.g. subsection 3.2). Moreover “Results” shouldn’t contain references, which additionally suggests combining it with “Discussion”. “Discussion” is basically focused on the Venice Lagoon, while other examined areas are barely mentioned. It must be improved. You even emphasize in “Introduction”, that other lagoons are poorly researched, and I suppose, that your paper was suppose to change it. Meanwhile, data for lagoons other than Venice, are not given in tables (see also below) and only on figure 2.  It would be also advisable to broaden the “Discussion” and make it more general, e.g. by comparing your results with other environments studied by other authors. You also mention some correlations between nutrients concentrations and grain composition of sediment, which seems to be interesting. However, it is not discussed and interpreted at all. Please, elaborate.      

Table 1 and 2: Adding “min” values would be advisable (in order to make it stay in line with Table 2). References should be putted in the form of numbers in []. Please, keep the same order of values in tables (e.g. min, max, mean, SD / min, mean, SD, max or other you see fit). Results form other lagoons should also be added (it may be in a form of separate table).

Figure 4 and section 3.3: You write: “Maps distribution of Ntot, Ptot, Porg in the surface sediments of the whole Venice Lagoon are available since 2003 (Fig. 4).” This sentence suggest, that maps on Figure 4 comes from literature. If so, add appropriate reference. Or are they based on your data and prepared by you? Please, clarify. Also you should describe methodology of preparing those maps, if applicable.

Thank you.

Author Response

Dear reviewer

We have appreciated the comments and suggestions that helped to improve the paper and have integrated the text accordingly. All adjustments, integrations and new references are in red.

GENERAL REMARKS

I propose to apply subscript in such terms as Ntot, Pinorg, Porg etc. to make it more clear.

It was done

Carefuly check the final version of the text, as some small mistakes and misprinting may be found.

Please make sure that numbers and units are on the same line in the text (e.g. lines 110-111: 65 cm; lines 146-147: 11 km2).

It was done

INTRODUCTION

This section is a bit too local. As you fairly noticed, nutrients may be treated as litmus paper of anthropogenic impacts and that is universal for many environments. Then, please put some more general information / background, regarding also other regions worldwide. The only “general” part of “Introduction” is the first paragraph, while others refer mainly to Venice lagoon. This “indigenousness” is also reflected in references, which are mainly Italian. It is not incorrect of course but looks a bit peculiarly and reduces scientific value of the paper. Moreover some information included in this section fit better to “Discussion” and may / should be relocated into this section.

This part was integrated adding many references of other international TWS.

Lines 66-70: You give some information about data for particular regions of Adriatic Sea, however it is not clear if you mean your data (discussed further in the paper) or some literature data. Please specify and put appropriate references, if applicable.   

These information were inserted in the text

MATERIALS AND METHODS

Figure 1 – figure shouldn’t be placed just below the title of a subsection. It should be preceded by some text. Moreover it should be located after (not before) its first citation.

Some text was inserted before this figure  with its first citation.

Lines 100-107: consider replacing [] by () while given a year(s), as [] are used for citation of references.

It was done

Methods are described quite briefly. Please add more details or refer to the literature. (Applies mainly to section 2.2.)

It was done

RESULTS and DISCUSSION

I propose to combine and reorganize those two sections, as some paragraphs of “Results” have a discussion character (e.g. subsection 3.2). Moreover “Results” shouldn’t contain references, which additionally suggests combining it with “Discussion”. “Discussion” is basically focused on the Venice Lagoon, while other examined areas are barely mentioned. It must be improved. You even emphasize in “Introduction”, that other lagoons are poorly researched, and I suppose, that your paper was suppose to change it. Meanwhile, data for lagoons other than Venice, are not given in tables (see also below) and only on figure 2.  It would be also advisable to broaden the “Discussion” and make it more general, e.g. by comparing your results with other environments studied by other authors. You also mention some correlations between nutrients concentrations and grain composition of sediment, which seems to be interesting. However, it is not discussed and interpreted at all. Please, elaborate.     

We prefer to keep these two sections separate as required by the author instructions of the journal.However, we have completely separated the results from the discussion.

In addition, the discussion was extended also to other international TWS inserting many references of nutrient concentrations in the sediment and comparing the literature data with those of the Italian lagoon.

Finally further discussion was added for the correlation of nutrient concentration with the sediment grain-size.

Table 1 and 2: Adding “min” values would be advisable (in order to make it stay in line with Table 2). References should be putted in the form of numbers in []. Please, keep the same order of values in tables (e.g. min, max, mean, SD / min, mean, SD, max or other you see fit). Results form other lagoons should also be added (it may be in a form of separate table).

In table 1 we have inserted only our results inserting also the min values whereas total results since the mid-20th century were added in a complete table reported in the Discussion section. References were also inserted in the form of number.

The  min, max and std values of the other stations were inserted in another table (Tab.1S) available on Supplementary Material.

Figure 4 and section 3.3: You write: “Maps distribution of Ntot, Ptot, Porg in the surface sediments of the whole Venice Lagoon are available since 2003 (Fig. 4).” This sentence suggest, that maps on Figure 4 comes from literature. If so, add appropriate reference. Or are they based on your data and prepared by you? Please, clarify. Also you should describe methodology of preparing those maps, if applicable.

This part was rewritten. The data available since 2003 have all been collected by our research group and with this study we have redrawn the maps also considering the samplings of 2014 and 2018. In addition, in the section “Materials and Methods” a new subsection  “2.4. Map preparation” was inserted explaining how these figures were obtained.

I hope I have answered your comments.

 

Best regards

Adriano Sfriso

Round 2

Reviewer 2 Report

I accept revised version of the manuscript.

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