Sediment Contamination and Toxicity in the Guadalquivir River (Southwest, Spain)
Octavio Jiménez-Garza
Ahmad Farid Abu Bakar
Round 1
Reviewer 1 Report
Interesting studies, well designed especially the toxicity tests - valuable methodological results.
Comments:
1) Figure 1 missing - makes analysis difficult - missing probably through inattention
2) is 5-10 cm layer appropriate for historical contaminants? No brief information on debris transport (U, W) and bottom structure (morphology) of erosion and deposition site - where samples were taken. Sampling from the current, shore zone? As located from river outlets and collectors - sources of pollution. This information would be advisable / valuable.
3) The study section is under reservoir pressure - what is the status of sediment quality in the reservoir? Are they being washed out by the outfalls? How often? When were the last flood (high flow) on the river? These factors can affect the top layer of sediment in the river.
4) The authors stress the importance of agriculture in the study area. Other pollutants (pesticides, fertilizers) not investigated (given), Sevilla big city = source of PAHs, PCBs etc. Co-existing pollutants may affect the response of eco-tests. Future plan.
5) What are the causes of AL sediment contamination higher than SE? - reservoir? agriculture?
Author Response
Open Review
(x) I would not like to sign my review report
( ) I would like to sign my review report
English language and style
( ) English very difficult to understand/incomprehensible
( ) Extensive editing of English language and style required
( ) Moderate English changes required
( ) English language and style are fine/minor spell check required
(x) I don't feel qualified to judge about the English language and style
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Does the introduction provide sufficient background and include all relevant references? |
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Are all the cited references relevant to the research? |
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Is the research design appropriate? |
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Are the methods adequately described? |
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Are the results clearly presented? |
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Are the conclusions supported by the results? |
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Comments and Suggestions for Authors
Interesting studies, well designed especially the toxicity tests - valuable methodological results.
Comments:
1) Figure 1 missing - makes analysis difficult - missing probably through inattention
Following the reviewer´s suggestion, the figure was introduced
2) is 5-10 cm layer appropriate for historical contaminants? No brief information on debris transport (U, W) and bottom structure (morphology) of erosion and deposition site - where samples were taken. Sampling from the current, shore zone? As located from river outlets and collectors - sources of pollution. This information would be advisable / valuable.
The current study is assessing the current health status of the ecosystems. The superficial layer, which is in direct contact with the water column, is occurring the most of chemical exchanges between water-sediment-biota. The most reactive contaminants are located in in the inmmediate layer, especially associated with fines for metals and organic matter (from decomposition), the aerial-oxic layer.
3) The study section is under reservoir pressure - what is the status of sediment quality in the reservoir? Are they being washed out by the outfalls? How often? When were the last flood (high flow) on the river? These factors can affect the top layer of sediment in the river.
The area of study is slightly affected by the reservoir but by the estuary of the river. In this sense, the sediments in the reservoirs were not characterized. Besides, there are not significant outfalls and the impact of the reservoir in the area is not considered based on the minimum impact. The SW of Spain is a dry area with low rain regimen so the reservoir does not affect significantly to the sediments in the studied area.
4) The authors stress the importance of agriculture in the study area. Other pollutants (pesticides, fertilizers) not investigated (given), Sevilla big city = source of PAHs, PCBs etc. Co-existing pollutants may affect the response of eco-tests. Future plan.
The study was focused just on inorganic elements-. Some of them are derived from it association as micronutrients (Fe, Zn) that currently appear as fertilizers. The agriculture and other contaminations sources were named in the manuscript to describe stressors of the study area.
5) What are the causes of AL sediment contamination higher than SE? - reservoir? agriculture?
The dam is retaining greater sediment, renovation of sediments is more difficult, therefore, there is a greater contamination accumulated
Author Response File: 
Author Response.docx
Reviewer 2 Report
There are some typos and spelling mistakes: line 12, "was" instead of "is", line 15: "studied" instead of "study"; line 79"were" is not neccesary, , line 356, "permits" insetad of "permit" line 240: usefulness insetad of useful, line 396, "have been" instead of "has been", line 404 "establisehed" instead of "establish" line 304 "significantly" instead of "significant". Line 296 it seems like "tubifex" is repeated
Author Response
Open Review
( ) I would not like to sign my review report
(x) I would like to sign my review report
English language and style
( ) English very difficult to understand/incomprehensible
( ) Extensive editing of English language and style required
( ) Moderate English changes required
(x) English language and style are fine/minor spell check required
( ) I don't feel qualified to judge about the English language and style
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Yes |
Can be improved |
Must be improved |
Not applicable |
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Does the introduction provide sufficient background and include all relevant references? |
(x) |
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Are all the cited references relevant to the research? |
(x) |
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Is the research design appropriate? |
( ) |
(x) |
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Are the methods adequately described? |
(x) |
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Are the results clearly presented? |
(x) |
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Are the conclusions supported by the results? |
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(x) |
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Comments and Suggestions for Authors
There are some typos and spelling mistakes: line 12, "was" instead of "is", line 15: "studied" instead of "study"; line 79"were" is not neccesary, , line 356, "permits" insetad of "permit" line 240: usefulness insetad of useful, line 396, "have been" instead of "has been", line 404 "establisehed" instead of "establish" line 304 "significantly" instead of "significant". Line 296 it seems like "tubifex" is repeated
Following the reviewer´s suggestion, all the changes were introduced
Author Response File: Author Response.docx
Reviewer 3 Report
1. Title need to be focus & more informative
2. Abstract need to be more informative
3. Provide detail description about motivation of this study. Detail description needed for study area, sediment type & characterization.
4. Explain why use all ICP MS, ICP OES & GF AAS in this single study?
5. Detail method about sample preparation is needed
6. Conclusion writing need to be improved
Comments for author File: 
Comments.pdf
Author Response
Open Review
( ) I would not like to sign my review report
(x) I would like to sign my review report
English language and style
( ) English very difficult to understand/incomprehensible
(x) Extensive editing of English language and style required
( ) Moderate English changes required
( ) English language and style are fine/minor spell check required
( ) I don't feel qualified to judge about the English language and style
|
Yes |
Can be improved |
Must be improved |
Not applicable |
|
|
Does the introduction provide sufficient background and include all relevant references? |
( ) |
( ) |
(x) |
( ) |
|
Are all the cited references relevant to the research? |
( ) |
(x) |
( ) |
( ) |
|
Is the research design appropriate? |
( ) |
( ) |
(x) |
( ) |
|
Are the methods adequately described? |
( ) |
( ) |
(x) |
( ) |
|
Are the results clearly presented? |
( ) |
( ) |
(x) |
( ) |
|
Are the conclusions supported by the results? |
( ) |
( ) |
(x) |
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Comments and Suggestions for Authors
- Title need to be focus & more informative
Following the reviewer´s suggestion, the title was modified and focused on Metal(loid)s as ssugested by the reviewer.
- Abstract need to be more informative
Following the reviewer´s suggestion, the abstract was modified
- Provide detail description about motivation of this study. Detail description needed for study area, sediment type & characterization.
The Guadalquivir River (SW, Spain) is the second longest river in Spain and the unique that allows navigation in the Estuary, being the main water source of a Spanish region with more than 7 million inhabitants. It ends into the Gulf of Cádiz, in the Atlantic Ocean, bordering Doñana National Park Reserve, which is the most important wintering site in Europe for a lot of birds. However, this region has been exposed for centuries to mining activities, which have greatly enriched the metal content of its water and soils.
Regarding the sediment type and characterization, it was focused on the metal and metalloids contamination and the organic matter content. Not additional characterization was conducted in the sediments. In any case, sediment type was mainly fine sediments deposited in the river bed.
- Explain why use all ICP MS, ICP OES & GF AAS in this single study?
The different instruments were employed accordingly to the detection range of the elements, i.e., Fe was better quantified by the ICP OES, and As is also better analyzed by absorbance coupled.
- Detail method about sample preparation is needed
Following the reviewer´s suggestion, the information was extended
For sampling:
Surface sediment samples (5-10 cm) were collected at the three described sites along the Guadalquivir River (AR, AL and SE) and the control site (RSP) with a 0.025 m2 Van Veen grab and transferred to a plastic bucket. When sufficient sediment had been collected from each station, the bucket was transported in a cooler to the laboratory. There, the contents of the bucket were homogenized with a Teflon spoon until no color or textural differences could be detected. The samples were subsampled for physical-chemical characterization and used for toxicological tests. They were kept at 4°C in dark until they were characterized or used for sediment toxicity testing, but no longer than 2 weeks.
For analyses:
Sediment aliquots for chemical analysis were dried at room temperature and then gently homogenized. Organic carbon content was determined by using [41] method. Aliquots of sediments were acid digested (65% H2NO3 and 33% H2O2) in closed vessels. Metals Cu, Zn, Fe, Co, Ni, Cd, and Pb, and the metalloid As were determined using ICP-MS, ICP-AES, and GF-AAS. The concentration was calculated on a dry weight basis. Results are expressed as mg kg-1 dry sediment. Reactive blanks and reference material (CRM478 BCR) were used to ensure the quality control.
- Conclusion writing need to be improved
Following the reviewer´s suggestion. the conclusion was improved
Author Response File: Author Response.docx
