Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Discussion papers
https://doi.org/10.5194/bg-2019-150
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-150
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 21 May 2019

Submitted as: research article | 21 May 2019

Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Biogeosciences (BG).

Long-term trends in pH in Japanese coastal waters

Miho Ishizu1, Yasumasa Miyazawa1, Tomohiko Tsunoda2, and Tsuneo Ono3 Miho Ishizu et al.
  • 1Japan Agency for Marine-Earth Science and Technology, Environmental Variability Prediction and Application Research Group, Yokohama Institute for Earth Sciences, 3173-25 Showa-machi, Kanagawa-ku, Yokohama 236-0001, Japan
  • 2The Ocean Policy Research Institute of the Sasakawa Peace Foundation, 1-15-16, Toranomon Minato-ku, Tokyo 105-8524, Japan
  • 3Japan Fisheries Research Education Agency, 15F Queen’s Tower B, 2-3-3 Minato Mirai, Nishi-ku, Yokohama, Kanagawa 220-6115, Japan

Abstract. In recent decades, acidification of the open ocean has shown consistent increases. However, analysis of long-term data in coastal waters shows that the pH is highly variable because of coastal processes and anthropogenic carbon inputs. It is therefore important to understand how anthropogenic carbon inputs and other natural or anthropogenic factors influence the temporal trends in pH in coastal waters. Using water quality data collected at 1481 monitoring sites as part of the Water Pollution Control Program, we determined the long-term trends in pH in Japanese coastal waters at ambient temperature from 1978 to 2009. We found that pH decreased (i.e., acidification) at between 70 % and 75 % of the sites and increased (i.e., basification) at between 25 % and 30 % of the sites. The rate of decrease varied seasonally and was, on average, −0.0014 yr−1 in summer and −0.0024 yr−1 in winter, but with relatively large deviations from these average values. While the overall trends reflect acidification, watershed processes might also have contributed to the large variations in pH in coastal waters. The seasonal variation in the average pH trends reflects variability in warming trends, while regional differences in pH trends are partly related to heterotrophic water processes induced by nutrient loadings.

Miho Ishizu et al.
Interactive discussion
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Miho Ishizu et al.
Miho Ishizu et al.
Viewed  
Total article views: 318 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
203 112 3 318 14 0 3
  • HTML: 203
  • PDF: 112
  • XML: 3
  • Total: 318
  • Supplement: 14
  • BibTeX: 0
  • EndNote: 3
Views and downloads (calculated since 21 May 2019)
Cumulative views and downloads (calculated since 21 May 2019)
Viewed (geographical distribution)  
Total article views: 256 (including HTML, PDF, and XML) Thereof 255 with geography defined and 1 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
No discussed metrics found.
Latest update: 16 Sep 2019
Publications Copernicus
Download
Short summary
Using water quality data collected at 1481 monitoring sites as part of the Water Pollution Control Program, we determined the long-term trends in pH in Japanese coastal waters at ambient temperature from 1978 to 2009. We found that pH decreased (i.e., acidification) at between 70 % and 75 % of the sites and increased (i.e., basification) at between 25 % and 30 % of the sites. The rate of decrease varied seasonally and was, on average, −0.0014 yr−1 in summer and −0.0024 yr−1 in winter.
Using water quality data collected at 1481 monitoring sites as part of the Water Pollution...
Citation