Marine Pollution by Microplastics in the Mediterranean Sea

Round 1

Reviewer 1 Report

The article provides information about microplastic pollution in the Mediterranean Sea.

There are several points of weakness:

As a communication manuscript, the article should be concise and informative.
1. An adequate definition of microplastics is missing, including types.
2. Possible sources of microplastics in the Mediterranean sea are missing.
3. You have selected three countries as the main contributors of plastic waste to the Mediterranean Sea. please refer to the following article for a better presentation of the data 
https://doi.org/10.1016/j.marpolbul.2018.02.019
4. No need for Fig. 2

5. It is interesting to provide monetary costs of the economic damage caused by plastic pollution, including losing key species. You can get updated information from the following website; https://www.unep.org/unepmap/resources/factsheets/pollution
6. Your conclusion and recommendation should be improved, please be noted that there is already a regional plan that has set binding statements to the Mediterranean countries.  

Author Response

1. I have added as follows: (Pag. 1 Lines 23-24) in the text: "Microplastics are small plastic fibers originating from daily objects."
2. I have added as follows: (Pag. 1 Lines 24-25) in the text:" The possible sources of these particles come from clothes, paints, tyre dust and personal care products."
3. I have added as follows: (Pag. 1 Lines 33-37) in the text: "Otherwise, if we consider only the plastic marine debris caused by terrestrial sources as coastline populations and river inputs, the relative rate per cent contributions of mediterranean countries are the following ones, in decreasing order: Turkey (97%), Morocco (94%), Israel (90%), Spain (89%), France (86%), Syria (86%), Egypt (84%), Albania (84%), Tunisia (82%) and Italy (80%) [3]."
4. (Pag. 2 Line 58) in the text: Figure 2 has been deleted.
5. I have added as follows (Pag. 2 Lines 43-44) in the text: "The yearly cost caused by plastic pollution in mediterranean waters is about of 61.7 million Euros, including the economic loss caused by overfishing [3]." 
6. I have added as follows (Pag. 3 Lines 69-72) in the text: "It is suggested by European Union [15] to urge Mediterranean countries in undertaking all the financial, legal and administrative measures to establish a sound and sustainable waste management system so to solve the problem of plastic pollution into the sea."

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear author,

I am very sorry to inform you that, in my view, your manuscript should not be published in its current state.

First of all, the english needs major improval, to a large extent the content is barely understandable. Furthermore, altough it is important to publish information on the source of marine debris pollution, it needs more content. Please be careful with the terms "marine debris" and "microplastics". Most of the time it is not clear to what category you are referring to. Furthermore, it is important to state unique and specific measurement to cope with the problem. Also it  should be outlined what is already going on in this direction in the countries addressed.

Please don't feel encouraged and see my critisism as aid for improval for your valuable information.

Comments for author File: Comments.pdf

Author Response

1. I review the English language in the manuscript to make the content more understable.
2. (Pag. 1 Line 16) in the text: I have deleted the word "debris" to avoid any mismatch in the meaning of this term.
3. (Pag. 3 Lines 72-77) in the text, I have added the sentences as follow." So, in Greece it has been suggested to perform an experimental trial for the biodegradation  of a mixture of plastic films through the microbial activities of bacterial populations. Also in Italy, it has been proposed a novel approach to reduce the plastic input, carried by water courses into the sea, through the realization of floating barriers placed just before river mouths, able to stop such plastic waste towards continental collecting site for the final recycling."

Author Response File: Author Response.pdf

Reviewer 3 Report

The communication entitled “Marine Pollution by Microplastics in the Mediterranean Sea” is a fascinating topic. I have read it with keen interest and have serious concerns due to the generalization and theories that may propound from this communication, especially to an oblivious readership that goes for a quick read and makes up their mind.

1. Line 7: “with serious health effects for mankind” the conclusion is based on what? There are about 7031 papers on microplastics so far; about 60% of the literature has found no effect on organisms themselves, leaving aside the human aspect. The author might have read some papers from Iran, Europe, etc., please see the concentrations, number of MPs in the human matrix, its toxicity etc. Please consider their aim, validity, and data quality objectives before such a statement can be generalized.
2. Line 8 – 10: “a concealed threat represented by microplastics that, through bio-accumulation processes, within the trophic net of marine ecosystems, produces high pollutant loadings in some edible species, causing severe risks for human health”. I have significant issues with this statement and will deal with it in parts.
3. What is the concealed threat?
4. More literature is published on high “egestion” and excretion than retention, especially of dominant particle sizes in the environment. So I am very concerned when such loose statements on bioaccumulation across the trophic level are made.
5. When you say high pollutant loadings does not imply exclusively to MPs and needs clarification and explicit mention of MP.
6. The concentration in MPs is within the digestive system, and for all those who eat muscle only, there are very few studies on levels in muscle (edible tissue).
7. Lines 10 – 11: “In the basin, the load of microplastics comes mainly from three coastal regions, as are Egypt, Turkey, and Italy in decreasing order” this might be true but based on how much data?. The higher content of MPs comes from wastewater treatment plants. It will be a factor of the population in catchment, and the quantity of treated and untreated effluent wastewater discharged into aquatic systems. The Moroccan and Tunisian coasts have high microplastic but I don’t have quantification for them. You might find some computed data in (Uddin et al., 2020) essentially of what comes through the wastewater stream as that is the most conspicuous input.
8. Line 13: emphasizes the need to undertake this research based on what? The treats of MPs are not so evident, although I don’t advocate that we should not do but it is overwhelming when we see the number of papers coming, there are more serious established threats from the several other emerging contaminants as well as the legacy pollutants where the effects are underpinned with solid science. Again I will draw your attention to a paper by this same group (Uddin et al., 2022), it provides an interesting rationale and skepticism and I personally tend to agree with some of their observations.
9. 1 the term “leakage” is not the most appropriate one for microplastics and does this data chart is for plastic or microplastic? Kindly give the source of this data as well.
10. Line 34: The reference is for plastic and not microplastic. I have found is quite usual for even the prolific writers to switch between plastic and microplastic. The two have very different input sources and fates. Although a simplistic assumption is taken that all plastic will eventually become MP.
11. Line 35: Again, the reference is to marine litter.
12. Line 38: what is the relationship between coastal and pelagic? It makes no sense.
13. Line 39: the concentration in coastal water is much higher than in the deep sea, so the statement is wrong.
14. Reference 13 is the risk of microplastic from the global ocean, and there is a serious concern with this value of 120,000 MP m^-3. This is too high and unrealistic to assume for coastal waters.
15. Line 44 – 46: what is the basis for suggesting sub-microscopic particles. There is no environmental study so far that has or can identify submicroscopic particles in an environmental sample. Most often, submicroscopic characterization is based on experimental study.
16. Figure 2 at best, is speculation; there is certainly no basis for this figure. The spelling needs to be checked. What is the difference between a carnivore and a predator?
17. I will like to caution the author not to make scientific basis and statements on the reports of WWF, they are seldom underpinned by sound science and are more of a journalistic view of often very complex environmental issues. Since this is a scientific communication you should not further these promiscuous views.
18. The conclusion is drawn by the author that there are UN SDGs that deal with microplastic and marine litter. The EU has its own guidelines underwater framework directives. Moreover, it clearly shows confusion on the writer’s part when there is no distinction between MP and litter.

 

Based on these communications, I am not comfortable suggesting publishing such a communication. It will promote more misconceptions rather than educating the audience on the scale and intensity of marine microplastics in the Mediterranean Sea.

Uddin, S., Fowler, S.W., Behbehani, M., 2020. An assessment of microplastic inputs into the aquatic environment from wastewater streams. Marine Pollution Bulletin 160, 111538.

Uddin, S., Fowler, S.W., Habibi, N., Behbehani, M., 2022. Micro-Nano Plastic in the Aquatic Environment: Methodological Problems and Challenges. Animals 12, 297.

Author Response

1. (Pag. 1 Line 7) in the text, I have deleted the word "serious".

(Pag. 1 Line 7) in the text, I have added the sentence, as follows: "with potential health effects on mankind, actually very debated in the scientific community".

2. (Pag. 1 Lines 8-10) in the text, I have deleted the sentence from lines 8 to 10.

3. (Pag. 1 Line 8) in the text, I have deleted the statement "concealed threat"

4. (Pag. 1 Lines 8-10) in the text, I have deleted the sentence from lines 8 to 10.

5. (Pag. 1 Lines 8-10) in the text, I have deleted the sentence from lines 8 to 10.

6. (Pag. 1 Lines 8-10) in the text, I have deleted the sentence from lines 8 to 10.

7. (Pag.1 Line 8) the data are released by Dalberg Advisors within the WWF Report 2019. 

8. (Pag. 1 Lines 9-11) in the text, I have added the sentence, as follows: "Today, the knowledge about the possible interactions of microplastics in the biotic system is unclear and, until now, big efforts are required to state their effects on human health."

(Pag. 1 Lines 28-30) in the text, I have added the sentence, as follows: "However, the real effects of microplastics on marine biota and on human health are still unclear and big efforts are required to really assess the consequences of microplastics on human health [6,7]."

9. (Pag. 1 Line 24) in the text, I have deleted the word "leakage".

10. (Pag. 2 Line 34) You are perfectly wright. The reference [7] is for marine litter.

11. (Pag. 2 Line 35) The reference [8] is for marine litter. 

12. (Pag. 2 Lines 37-39) in the text, the sentence from lines 37 to 39, with its reference [12] has been deleted.

13. (Pag. 2 Lines 39-43) in the text, the sentence from lines 39 to 43, with their references [13,14], has been deleted.

14. (Pag. 2 Lines 39-43) in the text,     Idem

15. (Pag. 2 Line 44) in the text, I have deleted the word "sub-microscopic".

16 (Pag. 2 Line 50) in the text, I have deleted the sentence from lines 46-49 and the relative Figure 2.

(Pag. 2 Line 50) in the text, I have added the statement, as follows: "until the last ones made by carnivores."

17. (Pag. 3 Line 52) You are right. In future, I will be very caution to avoid such promiscous views.

18. (Pag. 3 lines 69-72) in the text, I have added the sentence as follows: "It is suggested by European Union [15] to urge Mediterranean countries in undertaking all the financial, legal and administrative measures to establish a sound and sustainable waste management system for solving the problem of plastic pollution into the sea.  

Author Response File: Author Response.pdf

Reviewer 4 Report

This communication describes marine pollution by microplastics in the Mediterranean Sea. The author has presented rate percent of plastic leakage by different countries into the Mediterranean Sea. He reports that the sub-microscopic particles of this plastic debris enter the trophic system since the first steps of the marine food chain represented by planctonic biomass. Then, these polluting fractions move in the next steps of the scale from herbivores to carnivores up to predators through a process of bio-accumulation in a decimal logaritmic increase proceeding step by step along the trophic chain. At the end he presents a 5 points statement for an international agreement to be made among Mediterranean countries for controlling microplastic pollution in Mediterranean Sea, The work is interesting from environmental of view.  However, revision of the article is required before its suitability for publication in the light of following comments:

Abstract

1. The English language used in the abstract is not convincing. It should be revised.

Introduction

2. There is no information on the sources of microplastics. It should be added in the revised

text.

3. Public awareness program should be launched about negative impact of plastic use. This point should also be included in the statements of pollution control strategy.
4. There are several poorly written sentences. Revision is suggested.

 

Author Response

1. (Pag. 1 Lines 6-13) in the text, I have revised the English language and rewritten the abstract as follows."Worldwide, the waste of plastic debris into the sea is becoming a great environmental problem with potential health effects on mankind actually very debated in the scientific community. In the basin, the load of microplastics comes mainly from three coastal regions as are: Egypt, Turkey and Italy in decreasing order. Today, the knowledge about the possible interactions of microplastics in the biotic system is unclear and, until now, big efforts are required to state their effects on human health. Therefore, it is necessary to reduce the production and the use of plastics investing money in research planning and strengthening any kind of human efforts to solve this new kind of marine pollution. 

(Pag. 1 Line 14) in the text, I have deleted the word "bio-accumulation"

(Pag. 1 Line 14) in the text, I have added the word "marine pollution"

2.  (Pag. 1 Lines 24-25) in the text, I have added the sentence, as follows: "The possible  sources of microplastics come from clothes, paints, tyre dust and personal care products."

3. (Pag. 3 Lines 78-80) in the text, I have added the sentence, as follows: "Indeed, public knowledge is the main factor to better oppose against the negative impacts of plastic pollution in marine environment."

4. I have revised the English language in the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The author has improved the manuscript presentation.

Author Response

The author thanks the reviewer for his kind observation.