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Peer-Review Record

The Hydrochemistry and Recent Sediment Geochemistry of Small Lakes of Murmansk, Arctic Zone of Russia

Water 2020, 12(4), 1130; https://doi.org/10.3390/w12041130
Reviewer 1: Anonymous
Reviewer 2: ZhengYi Hu
Reviewer 3: Anonymous
Water 2020, 12(4), 1130; https://doi.org/10.3390/w12041130
Received: 6 March 2020 / Revised: 10 April 2020 / Accepted: 11 April 2020 / Published: 15 April 2020
(This article belongs to the Special Issue Geochemistry of Water and Sediment)

Round 1

Reviewer 1 Report

The manuscript entitled “The hydrochemistry and recent sediment geochemistry of small lakes of Murmansk, Arctic Zone of Russia” collected sediments in five small lakes located in Murmansk to evaluate the hydrochemistry and geochemistry. There are also a lot of question of formats and expression. In my opinion, this manuscript should be or revised with major amendments. The following are the questions and some mistakes in this manuscript:

  1. Please specify the specific sampling time. It is suggested to provide some information about the effects of different seasons on the hydrochemistry of small lakes of Murmansk.
  2. Why only choose Lake Semenovskoe to research the vertical distribution of heavy metals?
  3. Table 1, the name of "Lake Yuzhnoye" should be corrected to "Lake Yuzhnoe" in table 1.
  4. Line 80-106, it is suggested to provide the location relationship between the major pollution sources and the five small lakes or map out the main sources of pollutions in Figure 1.
  5. Line 168, Lake Yuzhnoe, not Lake Ledovoe, has the highest pH according to Table 2.
  6. Line 176-177, it is suggested to add more details about the standards of classification in [20].
  7. Table 2. It is suggested to list the background levels of the northeast lakes of Murmansk in the Barents sea catchment in Table 2.
  8. Line 205-207. According to table 2, the average value of TOC in the water of Lake Okunevoe and Lake Ledovoe is not less than the average of 7.7 mgC/L.
  9. Line 213-215. Arsenic is not mentioned in Table 3.
  10. Please explain the similarity between the content of NH4+ and the content of the main cation K+ in term of equivalent concentration in Line 187-188.
  11. Line 223, the “Table 2” should be “Table 3”.
  12. Line 303, what can also enter the environment with industrial emissions?
  13. Line 367-369. The dates of the Pollution Load Index of five lakes in the section “Sediments geochemistry” are not consist with that in the section “Conclusions”.
  14. The conclusion should be more concise.

Author Response

Reply to reviewer 1

 

Dear Reviewer,

 

We thank you for reviewing our publication. We have answered your comments and corrected the text and figures of the article. The corrected text has already been sent to the editorial office. You can see our answers to your comments below.

(The comments and suggestions of reviewers are in bold. They are left unchanged, including line numbers. Authors' replies were shown in italics. In the edited text of the article, all changes were highlighted in green)

 

 

Please specify the specific sampling time. It is suggested to provide some information about the effects of different seasons on the hydrochemistry of small lakes of Murmansk.

 

Line 117 – Field studies of the lakes were carried out in July 2018 and April and July 2019.

 

 

Why only choose Lake Semenovskoe to research the vertical distribution of heavy metals?

 

Lake Semenovskoe was chosen as the main lake in our science project, so we should study this lake more detailed than other urban lakes. Furthermore, Lake Semenovskoe is the most popular water object for citizens of Murmansk. However, the vertical distribution of heavy metals was made also for sediments of lake Okunevoe, not only for sediments of Lake Semenovskoe.

 

 

Table 1, the name of "Lake Yuzhnoye" should be corrected to "Lake Yuzhnoe" in table 1.

 

Line 78-79 - Typo has been fixed

 

 

Line 80-106, it is suggested to provide the location relationship between the major pollution

sources and the five small lakes or map out the main sources of pollutions in Figure 1.

 

Line 82-116 - Information about the location relationship between the major pollution sources and the studied lakes were added. Also, the main pollution sources were included on the map of figure 1.

 

 

Figure 1. Map of Murmansk’s area with studied lakes.

 

 

Line 168, Lake Yuzhnoe, not Lake Ledovoe, has the highest pH according to Table 2.

 

Line 192-195 - The text has been corrected: « One of the highest values (almost at the border between the alkaline and strongly alkaline values) were recorded in Lake Ledovoe, which receives water from the Varnichny Stream, running through the densely populated city core. The lake is located alongside the city's main street — Kola Avenue (figure 1). High water pH values also were recorded in Lake Yuzhnoe — ranging from 8.02 to 9.11 with an average of 8.42, which is considered alkaline and slightly alkaline»

 

 

Line 176-177, it is suggested to add more details about the standards of classification in [20].

 

Line 204-207 - According to the classification [20], all natural waters by chemical composition are divided in concordance with the prevailing anion (equivalents) into 3 classes: hydrocarbonate (and carbonate) (НСО3 + СО32–), sulfate (SO42–) and chloride (Сl). Each class according to the prevailing cation is divided into 3 groups: calcium (Ca2+), magnesium (Mg2+) and sodium (Na+).

 

 

Table 2. It is suggested to list the background levels of the northeast lakes of Murmansk in the Barents sea catchment in Table 2.

 

Line 219 - The background levels of the northeast lakes of Murmansk in the Barents Sea catchment are listed in Table 2:

Table 2. Average hydrochemical parameters of the Murmansk lakes.

Parameters

Units

Lakes

Background
[18]

Semenovskoe

Srednee

Okunevoe

Ledovoe

Yuzhnoe

pH

 

6.82

7.27

6.88

7.79

8.42

6.20

Cond20

µS/cm

111

207

91

866

407

31.8

Cond25

mS/m

12

23

10

95

45

3.5

Ca2+

mg/l

8.3

18.8

9.2

58.3

31.5

1.4

Mg2+

mg/l

2

3.9

2.1

10.3

8.5

0.8

Na+

mg/l

10.9

17.8

6.4

124.4

45.6

3.8

K+

mg/l

2.2

3.9

1.4

9.7

6.4

0.4

HCO3

mg/l

22

43

20

196

116

5.6

SO42–

mg/l

9.6

31.5

14.9

28.4

16.8

2.5

Cl

mg/l

17.8

24.7

8.9

185.4

68.9

5.4

TDS

mg/l

73

143

63

612

294

20

NH4+

µgN/l

187

30

24

3475

35

16

NO3

µgN/l

76

86.4

28.8

1.6

9

18

TN

µgN/l

542

369

315

3711

275

250

PO43–

µgP/l

4.6

0.8

2.25

37.8

4

2

TPf

µgP/l

7.2

3.8

5.5

47.6

10.33

4

TPunf

µgP/l

34.2

12.8

13.75

664

16.67

9

Color

Pt°

12.6

8

53.3

25.4

10.3

62

CODMn

mg/l

4.3

3.3

9.2

8

5.1

9.5

TOC

mgC/l

4.8

4.1

8.6

7.7

5.5

7.7

Si

mg/l

0.25

0.2

0.97

4.72

0.15

1.4

TDS – total dissolved solids; TPf – total phosphor filtered, TPunf – total phosphor unfiltered

 

 

Line 205-207. According to table 2, the average value of TOC in the water of Lake Okunevoe and Lake Ledovoe is not less than the average of 7.7 mgC/L.

 

Line 264-265 - Add to text: “, except for Lake Okunevoe and Lake Ledovoe where the average value of TOC in the water is not less than the background value.”

 

 

Line 213-215. Arsenic is not mentioned in Table 3.

 

Line 273 - Arsenic is removed from the article.

 

 

Please explain the similarity between the content of NH4+ and the content of the main cation K+ in term of equivalent concentration in Line 187-188.

 

Line 226-228 - The sentence is changed: “The content of NH4+ in Lake Ledovoe is equal to the content of the main cation K+ in terms of equivalent concentration (248 µeq/l).”

 

 

Line 223, the “Table 2” should be “Table 3”.

 

Line 283 - Typo has been fixed

 

 

Line 303, what can also enter the environment with industrial emissions?

 

Line 396 - This is about lead. A missing word has been added.

 

 

Line 367-369. The dates of the Pollution Load Index of five lakes in the section “Sediments geochemistry” are not consist with that in the section “Conclusions”.

 

Line 306-328 - The data in the Results and discussion section has been corrected.

 

 

The conclusion should be more concise.

 

Line 419-447 - The conclusion section is made a little shorter.

 

 

 

 

Author Response File: Author Response.doc

Reviewer 2 Report

PLease find the attached comments in files

Comments for author File: Comments.pdf

Author Response

Reply to reviewer 2

 

Dear Reviewer,

 

We thank you for reviewing our publication. We have answered your comments and corrected the text and figures of the article. The corrected text has already been sent to the editorial office. You can see our answers to your comments below.

(The comments and suggestions of reviewers are in bold. They are left unchanged, including line numbers. Authors' replies were shown in italics. In the edited text of the article, all changes were highlighted in green)

 

 

Abstract: The methodology should be further explained, including how to sampling depth (Line 107-109), sampling frequency, sampling number for each lake, season for sampling etc. should give background concentration of elements, and present concentration of elements.

 

According to the instructions for the authors, the number of words in the abstract should not exceed 200. In our text, we reflected on all the important points. Details can be found in the main body of the article.

 

The Murmansk thermal power plant, coal port, road and rail transport sites should be marked in Figure 1

 

Line 41, 42 - The main plants and pollution sources have been added in figure 1.

 

Figure 1. Map of Murmansk’s area with studied lakes.

 

 

Line 46language issue: replaced by?

 

Line 46, 49 - Word 'mazut' has been replaced on the other one 'fuel oil'

 

 

Line 47Emission? Should be detail materials? Including ** ?

 

Line 47-49 - Clarifications of the main pollutants emitted by TPPs have been added to the text: "According to the annual environmental reports for the Murmansk region, emissions of SO2, NO2, suspended substances, heavy metals and other pollutants from the Murmansk thermal power plant were 14 100 tons in 2017 and 15 310 tons in 2018."

 

 

Line 81-106: Should give distance between lakes and potential polluted sources (Murmansk thermal power plant, coal port, road and rail transport).

 

Line 82-116 - Information about the location relationship between the major pollution sources and the studied lakes were added

 

Line 107-107: Sampling season, date? Sampling number?

 

Line 117-120 - Field studies of the lakes were carried out in July 2018 and April and July 2019. A total of 18 water samples were taken (Lake Semenovskoe – 5, Lake Srednee – 5, Lake Okunevoe – 4, Lake Ledovoe – 5, Lake Yuzhnoe – 3).

 

 

Line 117-122: Sampling season, date? Sampling number for each lake?

 

Line 139-143 - One averaged sample was taken in July 2018 from each lake by the described way. This is usually sufficient when studying the sediments of lakes that cannot change too quickly. In addition, for assessment of dynamics of an accumulation of total concentration of heavy metals, a sediment core of the Lake Semenovskoe was collected in April 2019 using the Limnos gravity cover divided into 1 cm layers until the depth of 38 cm.

 

 

Line 142: Please give background concentration of elements and references.

 

Line 179-181 - For both indexes, the concentrations of studied elements in the pre-industrial layers of the sediments of small lakes in the Republic of Karelia, Russia were used as the background level (fig. 3).

 

 

Line 65. Should give detail for determination of elements in water, For example, whether the water sample is filtered

 

Line 121- 130 - Water samples were taken in polyethylene bottles from Nalgen®, the material of which does not have sorbing properties. Previously, the bottles were thoroughly washed in the laboratory. When sampling water, the bottles were rinsed twice with lake water, then placed in dark containers and refrigerated (~+4°C) in a short time transported to the laboratory. Filtration of water samples was carried out in the laboratory during discharge at the Millipore phase separation unit from high-density polypropylene through glass and polycarbonate membrane filters of Millipore HVLPO 4700, Schleicher & Schuell ME 25/21 ST, Whatman GF / A with a pore size of 0.45 μm. The following parameters were determined in unfiltered samples: pH, conductivity, alkalinity, CODMn, NH4+, NO3–, PO43+, TPunf, metals (after acidification with concentrated nitric acid). In the filtered samples, Si, TPf, color, Cl, SO42+ were determined.

 

 

Line 154: Are the depth and volume available in a few decades year ago? Water enrichment could be one of factors resulted in increase of pH, concentration of selected elements. Please check it. Is there seasonal eutrophication in these lakes?

 

Unfortunately, there are no such data for studied urban lakes. Our research is unique for these natural objects.

 

 

Line 286-288. Please give year for the operation of a thermal power plant using fuel oil

 

Line 350 - The beginning time of the operation of the TPP on fuel oil is indicated. It is the 1960s.

 

 

Line 14. Misnomer. “Findings” could be replaced by “investigation”. Check for full text.

 

Line 31 - The first sentence of the Abstract section has been changed: “This paper presents the first study of five small lakes located in the city of Murmansk”

 

 

The conclusion is not refined and needs to be further refined.

 

Line 419 - Section conclusion corrected after making all changes to other sections of the article

 

Author Response File: Author Response.doc

Reviewer 3 Report

I thought that this was an interesting manuscript, especially the section on sediment heavy metals. I would suggest publication with some minor changes.

Some minor comments:

Figure 1. Please show the location of the Murmansk Thermal Power Plant,

Mazut. Please define. (I had to Google it to find out what it was.)

Lines 47 - 48, and lines 275 - 276. What are the main constituents of the emissions? CO2, metals, ash, etc ?

Lines 110, 118. I think that the methods could be better described here. The methods for the sediment analyses were better described further down this section.

Section 3.1. Could the water chemistry be illustrated as a ternary diagram (an addition small figure). May assist to reduce the amount of text at the bottom of page 5.

Lines 187 - 189. Do the deeper of the lakes thermally stratify in summer (or when the samples were collected) and develop an anoxic hyperlimnion? When there are high concentrations of NH4, were there also low concentrations of dissolved oxygen? Line 194 and line 196 suggest a reducing environment. I agree, but ask if it is due to thermal stratification and the decomposition of high loads of organic matter in the bottom waters causing anoxia?

Lines 200 - 202 - High P concentrations (especially PO4) also suggests an anoxic hypolimnion.

Line 190. Ledovoe (not Ledovoye)

Lines 205 - 212. Lake Okunevoe according to Page 4 has surrounding forest.  Suggests to me a similarity in regards colour and TOC to the polyhumic forest lakes of the boreal forest regions of Finland, on which plenty has been published.

Line 213. As not mentioned anywhere else in the manuscript (in Methods or Results). Delete from this line.

Lines 282 - 291. Was any dating done on the sediment cores? It would be nice if dates could be supplied for parts of the core, especially at 16 cm. Also the top 5 or 6 cm where Pb starts to decrease. And right at the bottom (36 cm) as a pre-industrial reference.

Line 303. Should this read "In addition, Pb can also enter the environment....."?

Lines 320 - 327. English could be improved.

Line 323 - 324. Sb is mentioned twice. One of these should be V instead, I think, as it is shown in Fig 5 but not mentioned in these lines of text.

Figures 4 and 5. These suggest to me that there has been an increase in the sediment accumulation rate in the lakes in recent years.  Lots of sediment now being washed in?

Lines 357 - 364. Do summer algal blooms occur in the lakes with higher N and P concentrations? If so, these are likely to elevate the pH.

Lines 374 - 383. I think that a discussion of the potential sources of pollution to the lakes in the manuscript is worthwhile, but delete the last sentence (lines 382 - 383).

Do they use salt or any other products to de-ice the streets of Mumansk during winter? If so, some of this could run off into the lakes causing further pollution. 

Author Response

Reply to reviewer 3

 

Dear Reviewer,

 

We thank you for reviewing our publication. We have answered your comments and corrected the text and figures of the article. The corrected text has already been sent to the editorial office. You can see our answers to your comments below.

(The comments and suggestions of reviewers are in bold. They are left unchanged, including line numbers. Authors' replies were shown in italics. In the edited text of the article, all changes were highlighted in green)

 

 

Figure 1. Please show the location of the Murmansk Thermal Power Plant

 

Line 41, 42 - The Murmansk TPP and other enterprises were shown in Figure 1.

 

 

Mazut. Please define. (I had to Google it to find out what it was.)

 

Line 46, 49 - Word 'mazut' has been replaced on the other one 'fuel oil'

 

 

Lines 47 - 48, and lines 275 - 276. What are the main constituents of the emissions? CO2, metals, ash, etc ?

 

Line 46-49 - list of main pollutants added according to state environmental reports

 

 

Lines 110, 118. I think that the methods could be better described here. The methods for the sediment analyses were better described further down this section.

 

Line 117-143 - Description of methods has been improved. The description of the methods was moved to the place indicated by the reviewer.

 

 

Section 3.1. Could the water chemistry be illustrated as a ternary diagram (an addition small figure). May assist to reduce the amount of text at the bottom of page 5.

 

Line 249-252 - The authors thank the reviewer for the proposal to construct a ternary diagram. The ternary diagram is constructed for the basic cations and anions, which shows two groups of the lakes by the predominant ions – chloride-sodium and hydrocarbonate-calcium.

 

 

Lines 187 - 189. Do the deeper of the lakes thermally stratify in summer (or when the samples were collected) and develop an anoxic hyperlimnion? When there are high concentrations of NH4, were there also low concentrations of dissolved oxygen?

Line 194 and line 196 suggest a reducing environment. I agree, but ask if it is due to thermal stratification and the decomposition of high loads of organic matter in the bottom waters causing anoxia?

 

Line 238-245 - During water sampling in rather deep Murmansk’s urban lakes (Table 1), summer and winter thermal stratification occurred in July and April, respectively, when the denser (colder in summer and relatively warmer in winter) waters are located in the deep layers of the lake water column. The thermal and density stratification does not allow mixing of the lake water column; therefore, a reducing environment with high NH4+ concentrations is formed in deep water layers as a result of the decomposition of high loads of organic matter. The smell of hydrogen sulfide emanating during the sediments sampling confirms the conclusion about the reducing environment in the deep layers of the water column.

 

 

Lines 200 - 202 - High P concentrations (especially PO4) also suggests an anoxic hypolimnion.

 

Line 259-261 - Add to text: “High phosphorus concentrations (especially PO43–), as well as high NH4+ concentrations, suggests an anoxic hypolimnion in the water of Lake Ledovoe”.

 

 

Line 190. Ledovoe (not Ledovoye)

 

Line 231 - Typo has been fixed

 

 

Lines 205 - 212. Lake Okunevoe according to Page 4 has surrounding forest.  Suggests to me a similarity in regards colour and TOC to the polyhumic forest lakes of the boreal forest regions of Finland, on which plenty has been published.

 

Line 270-272 - Add to text: “Lake Okunevoe has surrounding forest and a similarity in regards Color and TOC to the polyhumic forest lakes of the boreal forest regions of Finland, on which plenty has been published (for example, Kauppila et al., 2016; Asmala et al., 2019).”

 

Line 528-533 - Asmala E., Carstensen J., Räike A. Multiple anthropogenic drivers behind upward trends in organic carbon concentrations in boreal rivers. Environ Res Lett 2019; 14: 124018. DOI: 10.1088/1748-9326/ab4fa9.

Kauppila T., Ahokas T., Nikolajev-Wikström L., Mäkinen J., Tammelin M.H., Meriläinen J.J. Aquatic effects of peat extraction and peatland forest drainage: a comparative sediment study of two adjacent lakes in Central Finland. Environ Earth Sci 2016; 75: 1473. DOI 10.1007/s12665-016-6278-x.

 

 

Line 213. As not mentioned anywhere else in the manuscript (in Methods or Results). Delete from this line.

 

Line 273 - Arsenic is removed from the article.

 

 

Lines 282 - 291. Was any dating done on the sediment cores? It would be nice if dates could be supplied for parts of the core, especially at 16 cm. Also the top 5 or 6 cm where Pb starts to decrease. And right at the bottom (36 cm) as a pre-industrial reference.

 

Unfortunately, we didn't assess sediment age. But we necessarily are going to do it in the close future. Now we base the age of core sediment of the Lake Semenovskoe using geochemical indicators. The main one of them is vanadium, which enters the lakes from the emission of the thermal power plant.

 

 

Line 303. Should this read "In addition, Pb can also enter the environment....."?

 

Line 369 - Yes, we have fixed this typo

 

 

Lines 320 - 327. English could be improved.

 

Line 386-391 - We reformulated the sentences in this paragraph.

 

Line 323 - 324. Sb is mentioned twice. One of these should be V instead, I think, as it is shown in Fig 5 but not mentioned in these lines of text.

 

Line 389 - Typo has been fixed

 

 

Figures 4 and 5. These suggest to me that there has been an increase in the sediment accumulation rate in the lakes in recent years.  Lots of sediment now being washed in?

 

Unfortunately, we have not yet analyzed the sedimentation rate in this lake using the analysis of Pb isotopes, but we did it using geochemical markers. Most likely, the sedimentation rate may change over time, but we will talk about this more precisely in the following publications.

 

 

Lines 357 - 364. Do summer algal blooms occur in the lakes with higher N and P concentrations? If so, these are likely to elevate the pH.

 

Line 245-247 - Add to text: “Massive development of cyanoprokaryotes was noted in Lake Ledovoe in the summer, which causes an increase in the water pH value. The pH value in the surface water layer in July 2019 was 9.34, and in the bottom layer – 7.18.”

 

 

Lines 374 - 383. I think that a discussion of the potential sources of pollution to the lakes in the manuscript is worthwhile, but delete the last sentence (lines 382 - 383).

 

Line 447 - Excess sentence removed in this paragraph

 

 

Do they use salt or any other products to de-ice the streets of Murmansk during winter? If so, some of this could run off into the lakes causing further pollution.

 

Line 425 - Add to text: “…, as well as the use of reagents for deicing processing of urban roads,…”

Author Response File: Author Response.doc

Round 2

Reviewer 1 Report

The authors have addressed all the comments. I have no further comments.

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