Riparian and in-stream controls on nutrient concentrations and fluxes in a headwater forested stream

Bernal, S.; Lupon, A.; Ribot, M.; Sabater, F.; Martí, E.

doi:https://doi.org/10.5194/bg-12-1941-2015

Articles | Volume 12, issue 6

https://doi.org/10.5194/bg-12-1941-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/bg-12-1941-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 12, issue 6

Research article

|

24 Mar 2015

Research article |

| 24 Mar 2015

Riparian and in-stream controls on nutrient concentrations and fluxes in a headwater forested stream

S. Bernal, A. Lupon, M. Ribot, F. Sabater, and E. Martí

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Final revised paper (published on 24 Mar 2015)
Supplement to the final revised paper
Preprint (discussion started on 29 Jul 2014)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC C4987: 'review of Bernal et al.', Anonymous Referee #1, 09 Sep 2014
- AC C7658: 'response to reviewers bg-2014-324', Susana Bernal, 27 Dec 2014
RC C5124: 'Review of “Riparian and in-stream controls on nutrient concentrations along a headwater forested stream” by Bernal and others', Anonymous Referee #2, 15 Sep 2014
- AC C7657: 'response to reviewers bg-2014-324', Susana Bernal, 27 Dec 2014
RC C5893: 'Review S. Bernal et al., Riparian and in-stream controls', Anonymous Referee #3, 13 Oct 2014
- AC C7656: 'response to reviewers bg-2014-324', Susana Bernal, 27 Dec 2014

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Susana Bernal on behalf of the Authors (29 Dec 2014) Author's response Manuscript

ED: Referee Nomination & Report Request started (11 Jan 2015) by Tom J. Battin

RR by Anonymous Referee #2 (30 Jan 2015)

RR by Anonymous Referee #3 (28 Feb 2015)

Suggestions for revision or reasons for rejection

This manuscript is greatly improved from the original submission, I now modify my introductory sentence to the first review, by deleting “potentially,” viz.:

This is a pioneering and important contribution to the long standing question of whether, how, and to what extent in-stream biogeochemical processes influence stream chemistry.

I greatly appreciate the authors’ attention to my previous review and the great effort they have made in in revising the manuscript. The inclusion of the whole-reach analyses is a particularly strong enhancement. One further suggestion (for authors’ discretion) would be to work in Table R3, which appears in the authors’ response, but not in the text. I have quite a few, mostly editorial, comments, but basically the paper is in good shape. I suspect this paper will be highly influential.

Line-referenced comments:

25-26: There is not enough background to make the sentence intelligible. The reader cannot be expected to understand that the 6, 18, and 20% refer to the average (median) of the absolute value of effects measured on a given date on a stream segment that is typically 200 m long. I suggest the following:

In stream net nutrient uptake (Fsw) was highly variable across contiguous segments and over time, but its temporal variation was not related to the vegetative period of the riparian forest. Within segments and dates, Fsw, whether negative or positive, accounted for a median of 6, 18, and 20% of the inputs of NO3, NH4+, and SRP, respectively.

56: “major influence” should be “larger influence”.
60: write “capable of decreasing”
79: write “processes of these two”
107: write “We chose”
109: write “pronounced”
129: write “fell within the long-term”
130: write “summer 2010”
145: write “fold” not “folds”. “Folds” is not standard English, but appears many times in the manuscript. Usually, “fold” is correct. “Times” may sometimes work as a substitute.
175: “with a YSI”
176: “avoided”
214: “leaf-out”, “leaf-litter”
280: “FSW being”
287: consider using “tributary” instead of “effluent” which generally means wastewater from a pipe.
324: Does Fin exclude in-stream sources (Fsw<0)? I would think so, but Table 4 shows relative contributions from all four sources that, including FSw, add up to less than 100%. See comment re: line 857.
331: I find the expression Fgw>0/Fin confusing because it violates standard rules of mathematical precedence, which would call for dividing 0 by F before comparing to Fgw. The correct presentation would be (Fgw>0)/Fin.
413: Meaning is unclear. Do you mean “between-nutrient differences in FSW were not statistically significant” ?
417: “sinks” should be “sink”.
437-438: Doesn’t Figure 7a also show a net retention in December of 2011?
439: “consistently” should be “generally,” since as you note in line 441, it is not consistent.
525. “not only be explained” should read “not be explained entirely by”.
556-558. Awkward non-standard English. “than” should be “as”. Suggest. “It is worth noting that longitudinal trends in stream nutrient concentrations showed no simple relationship to in-stream processes. Other sources of variation of stream water chemistry were counterbalancing the influence of in-stream processes on stream nutrient fluxes”
565-567: Good! I agree.
569: “despite this may not result in” should be “even in the absence of”
571: Here you say nitrification could explain the nitrate increase in the last 700 m, but doesn’t line 525 say that nitrification is insufficient to explain the increase?
575: write “(FSW>0)/Fin = 10%”, i.e., add parentheses.
575: I understand that the point is that in-stream processes may not explain the trend, but this leaves the reader hanging as to what might explain the trend. Might the decrease have been from lower concentrations of groundwater and tributary inputs? I see that you suggest this for SRP on line 581.

Table 4:
850: Specify whether this Table is based on whole-reach budgets.
851: should read “[(Fgw>0)/Fin]”
852: add a bar and parentheses to get “[|(Fsw<0)/Fin|]”
854: should read “p<0.01”.
857: The median contributions don’t add to 100%. Is this simply because they are medians and not means? If so, it might be helpful to note this. If not, then why don’t they add up? This is the more puzzling because the first three are the components of Fin (as defined on line 324) and so by themselves should roughly total to 100%.

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ED: Publish subject to technical corrections (01 Mar 2015) by Tom J. Battin

AR by Susana Bernal on behalf of the Authors (03 Mar 2015) Author's response Manuscript

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Short summary

Terrestrial inputs are considered the major driver of longitudinal patterns of nutrient concentration. Yet we show that longitudinal trends result from hydrological mixing with terrestrial inputs and in-stream processes. We challenge the idea that nutrient concentrations decrease downstream when in-stream net uptake is high. Conversely, in-stream processes can strongly affect stream nutrient chemistry and fluxes even in the absence of consistent longitudinal trends in nutrient concentration.