Effects of different N sources on riverine DIN export and retention in  a subtropical high-standing island, Taiwan

Huang, Jr-Chuan; Lee, Tsung-Yu; Lin, Teng-Chiu; Hein, Thomas; Lee, Li-Chin; Shih, Yu-Ting; Kao, Shuh-Ji; Shiah, Fuh-Kwo; Lin, Neng-Huei

doi:https://doi.org/10.5194/bg-13-1787-2016

Articles | Volume 13, issue 6

https://doi.org/10.5194/bg-13-1787-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/bg-13-1787-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 13, issue 6

Research article

|

23 Mar 2016

Research article |

| 23 Mar 2016

Effects of different N sources on riverine DIN export and retention in a subtropical high-standing island, Taiwan

Jr-Chuan Huang, Tsung-Yu Lee, Teng-Chiu Lin, Thomas Hein, Li-Chin Lee, Yu-Ting Shih, Shuh-Ji Kao, Fuh-Kwo Shiah, and Neng-Huei Lin

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Final revised paper (published on 23 Mar 2016)
Supplement to the final revised paper
Preprint (discussion started on 07 Oct 2015)

Interactive discussion

Status: closed

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

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- Supplement

SC C7100: 'Interactive discussion, 26 Oct 2015', Wangshou Zhang, 26 Oct 2015
- AC C9016: 'Reply to Dr. Zhang', Teng-Chiu Lin, 14 Jan 2016
RC C7658: 'Review', Anonymous Referee #1, 12 Nov 2015
- AC C9022: 'Reply to review #1', Teng-Chiu Lin, 14 Jan 2016
RC C8560: 'Review Comments', Anonymous Referee #2, 18 Dec 2015
- AC C9031: 'Reply to review #2', Teng-Chiu Lin, 14 Jan 2016

Peer-review completion

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

ED: Reconsider after major revisions (27 Jan 2016) by Brian A. Pellerin

AR by Teng-Chiu Lin on behalf of the Authors (03 Feb 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Feb 2016) by Brian A. Pellerin

RR by Anonymous Referee #1 (19 Feb 2016)

RR by Anonymous Referee #2 (03 Mar 2016)

Suggestions for revision or reasons for rejection

I appreciate the effort made to revise the manuscript based on the reviews submitted. All suggestions were addressed in a thorough and thoughtful manner. The methods section has been significantly expanded and it is now possible to understand how the input/output budgets were calculated. The authors have identified and discussed some of the shortcomings of the estimates used. They have discussed the limitations of the sampling strategy and although the strategy is not ideal they make a good argument that the results are comparable among the watersheds sampled.

I have no further substantive comments, however I have included several editorial suggestions for your consideration:
Page 2 Line 37: Typo land cover, not “land and cover”

Page 2 Line 42: Editorial correction “…urges the need to increase the proportion of households connected to a sewage system and improve the …”

Page 5 Line 87: Delete “provides scientific evidences of” replace with “documents”

Page 6 Line 111: “This urges the need of sewage treatment systems for the large quantity of domestic wastewater. Delete this sentence, it is not necessary. Save your recommendation for more widespread sewage systems for the discussion and conclusions.

Page 6 Line 112: Typo “There are a total of 49 wastewater…”

Page 6 Line 119 Typo: .”…agricultural lands ¬are mainly…”

Page 6 Line 120: Editorial correction “The agriculture in Taiwan is characterized by…”

Page 7 Lines 126-7: Editorial correction: combine the two sentences “…usually along roadsides or streamsides with some distributed in uplands with tea…”

Page 7 Line 37 Editorial correction: “distributed” not “distributing”

Page 7 Line 147 “In contrast…”

Page 8 Line 149 Editorial correction “to 0.38” is repeated

Page 8 Line 155 Editorial suggestion “Atmospheric N deposition, synthetic fertilizer use, and human emissions data are collected…”

Page 12 Line 265: Typo “Mean total annual…”

Page 12 Line 268: “…it could not cause the large increase in total N input..” not “deposition”. You are talking about the fraction of input accounted for by deposition.

Page 13 Line 287: “Giv¬en the global land area of …”

Page 13 Lines 288-289: “Comparing to this global picture, the level of riverine DIN export in Taiwan, ~3800 kg-N km-2yr-1, is extraordinarily high as it is 18 times of the global average.”
Suggested edit: “Our estimate of the riverine DIN export for Taiwan is ~3800 kg-N km-2yr-1, 18 times the global average.”

Page 14 Line 309: Suggested edit “…high end of the global scale...” rather than global picture

Page 15 Line 327: “coupled” not “coupling”

Page 17 Line 380: “held” not “hold”

Page 17 Line 382: I suggest “unrelated rather than “irrelevant”

Page 17 Line 392: “Campbell et al. (2000) suggested that the …” you need to be explicit about who made the suggestion

Page 18 Line 395: Editorial suggestion “…which are mainly distributed…”

Page 18 Line 395: Typo “…mean riverine export ration…” the “n” in mean is missing, also should be “ratio” not “ratios”

Page 18 Line 398: Editorial suggestion “Prior to the 1980s, forests were under…”

Page 18 Line 402: “…prohibited in 1991…”

Page 18 Line 410: Typo “slope” missing the “e”

Page 19 Lines 420-421: Editorial suggestion “…agricultural lands could significantly reduce DIN export.”

Page 19 Line 421-422: Editorial suggestion “The highly-disturbed watersheds had much larger DIN export ratios than the moderately disturbed watersheds, likely a results of higher population density and agricultural intensity.”

Page 19 Line 424: Typo “ratios”

Page 19 Lines 433-435: “Thus, increasing the proportion of households connected to sewage systems and improving the effectiveness of new and existing systems would probably be the most effective measure to reduce riverine DIN export in Taiwan and other regions with high population densities.”

Page 20 Line 438: “characterized” rather than “characterize”

Page 20 Lines 448-449: Editorial suggestion “The high N export poses a risk of eutrophication to downstream ecosystems including coastal waters.”

Page 20 Lines 461-463: Editorial suggestion “Increasing the proportion of households connected to a sewage systems and improving the effectiveness of the sewage systems are important considerations for reducing N export.”

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ED: Publish subject to technical corrections (04 Mar 2016) by Brian A. Pellerin

AR by Teng-Chiu Lin on behalf of the Authors (06 Mar 2016) Manuscript

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Short summary

The mean riverine DIN export of 49 watersheds in Taiwan is ∼ 3800 kg N km⁻² yr⁻¹, 18 times the global average. The mean riverine DIN export ratio is 0.30–0.51, which is much higher than the average of 0.20–0.25 of large rivers around the world, indicating excessive N input relative to ecosystem retention capacity. The DIN export ratio is positively related to agriculture input, and levels of human disturbance and watersheds with high DIN export ratios are likely at advanced stages of N excess.