the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 05 Dec 2024
Biogeochemical Layering and Transformation of Particulate Organic Carbon in the Tropical Northwestern Pacific Ocean Inferred from δ13C
Abstract. Particulate organic carbon (POC) serves as the main carrier of the biological pump and determines its transmission efficiency, yet the transformation processes of POC remain incompletely understood. This study reports the vertical distribution of POC, dissolved inorganic carbon (DIC), δ13C-POC, and δ13C-DIC in the tropical Northwestern Pacific Ocean (TNPO). The research identified three distinct biogeochemical layers governing POC transformation: the POC rapid synthesis-degradation layer (RSDL, 0–300 m), the net degradation layer (NDL, 300–1,000 m), and the stable layer (SL, 1,000–2,000 m). From the top to the bottom of the RSDL, δ13C-POC decreased by an average of 2.23 ‰, while the carbon-to-nitrogen ratios (C:N) increased by an average of 2.3:1, indicating the selective degradation of POC. In the NDL, δ13C-POC and δ13C-DIC exhibited a significant negative correlation (r = 0.43, p < 0.05), indicating a net transformation of POC to DIC. In the SL, POC proved to be resistant to degradation, with POC exhibiting the highest C:N (15:1 on average) and the lowest δ13C-POC (average -27.71 ‰).
- Preprint
(2720 KB) - Metadata XML
- BibTeX
- EndNote
Status: open (until 19 Feb 2025)
-
RC1: 'Comment on egusphere-2024-3467', Anonymous Referee #1, 13 Jan 2025
reply
While this paper represents new data on POM elemental and stable isotope composition (which is always welcome) and the interpretation given appears fairly senseful, though largely speculative. But because the data set is limited to ‘classical’ parameters of POM and does not provide more specific data about POM composition (e.g. isotopic composition of specific components) the paper falls short in substantially improving our insights in the fate of POM in the oceanic water column with regard to existing literature.
A further major shortcoming of this paper is the one-dimensional (surface to deep) approach used when interpreting the data, despite the apparent complexity of ocean currents and counter currents in the studied area. No use is made of T-S, nutrient data to inform on mixed layer depth, DCM position and to identify major water masses and possible impacts of advection processes on observed profiles.
The method section should be more detailed, since no information on sample preservation, standards, references used, corrections applied .. is given.
Citation: https://doi.org/10.5194/egusphere-2024-3467-RC1 -
AC1: 'Reply on RC1', Xuegang Li, 16 Jan 2025
reply
We sincerely thank you for your valuable time and insightful comments on our manuscript. We have carefully considered each of the issues raised and made corresponding revisions to the manuscript. Detailed responses to all comments are provided in the attached document titled "Response to RC1". Your feedback has been instrumental in improving the clarity and scientific rigor of our study, and we greatly appreciate your constructive suggestions.
-
RC2: 'Reply on AC1', Anonymous Referee #1, 17 Jan 2025
reply
I appreciate the fact that a T-S diagram has been provided. The depth scale in color gradient is not really necessary as it renders the reading of the graph more difficult and since in any case isopycnals are shown. So, either remove the depth scale or consider plotting another parameter instead of depth (DIC, d13C, or may be try plotting nitrate or phosphate, for which you have data).
You mention NPSSW, which does not appear in the T-S plot; do you mean NTPSSW?
In order to address my concern about absence of discussion how water masses might possibly affect the vertical distributions of studied parameters, I wonder whether you could indicate the position of the different water masses present at each of the stations (vertical profiles in Figs 2 and 4).
In Fig. 1 you show an arrow marked ‘NGCUC’ along the PNG coast. It was not identified and discussed.
Citation: https://doi.org/10.5194/egusphere-2024-3467-RC2
-
RC2: 'Reply on AC1', Anonymous Referee #1, 17 Jan 2025
reply
-
AC1: 'Reply on RC1', Xuegang Li, 16 Jan 2025
reply
Data sets
Vertical layering and transformation of particulate organic carbon in the tropical Northwestern Pacific Ocean waters based on δ13C Detong Tian, Xuegang Li, Jinming Song, Jun Ma, Huamao Yuan, and Liqin Duan https://doi.org/10.6084/m9.figshare.26197808
Viewed
| HTML | XML | Total | BibTeX | EndNote | |
|---|---|---|---|---|---|
| 84 | 18 | 5 | 107 | 3 | 3 |
- HTML: 84
- PDF: 18
- XML: 5
- Total: 107
- BibTeX: 3
- EndNote: 3
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1