Ocean acidification and its regulating factors in the East China Sea off the Yangtze River estuary

Qinyu Liu; Bin Wang; Yanyi Miao; Dewang Li; Haiyan Jin; Jianfang Chen

doi:10.1016/j.marenvres.2025.106960

Ocean acidification and its regulating factors in the East China Sea off the Yangtze River estuary

Mar Environ Res. 2025 Jan 10:204:106960. doi: 10.1016/j.marenvres.2025.106960. Online ahead of print.

Authors

Qinyu Liu¹, Bin Wang², Yanyi Miao³, Dewang Li⁴, Haiyan Jin⁵, Jianfang Chen⁶

Affiliations

¹ Donghai Laboratory, Zhoushan, Zhejiang, 316021, China; Ocean College, Zhejiang University, Zhoushan, 316021, China.
² Donghai Laboratory, Zhoushan, Zhejiang, 316021, China; Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China. Electronic address: [email protected].
³ Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China; School of Oceanography, Shanghai Jiaotong University, Shanghai, 200240, China.
⁴ Donghai Laboratory, Zhoushan, Zhejiang, 316021, China; Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China; Observation and Research Station of Yangtze River Delta Marine Ecosystems, Ministry of Natural Resources, Zhoushan, 316021, China.
⁵ Donghai Laboratory, Zhoushan, Zhejiang, 316021, China; Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China; State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China; School of Oceanography, Shanghai Jiaotong University, Shanghai, 200240, China. Electronic address: [email protected].
⁶ Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China; State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China.

PMID: 39818104
DOI: 10.1016/j.marenvres.2025.106960

Abstract

This study examines the seasonal variations in carbonate system parameters in the East China Sea (ECS) off the Yangtze River estuary (YRE) and analyzes the contributions of anthropogenic CO₂ and eutrophication to acidification. Carbonate parameters data were collected during summer 2019 and combined winter 2011. During winter, acidification is primarily driven by rising atmospheric CO₂, with minimal impact from biological processes. In contrast, summer presents a different pattern: enhanced photosynthesis due to eutrophication in surface waters helps mitigate the acidification effects of atmospheric CO₂ increases, while in bottom waters, the combined pressures of atmospheric CO₂ and intensified aerobic respiration leads to more severe acidification. Notably, biological processes now contribute more to acidification than increasing atmospheric CO₂ in the bottom waters. Our projections indicate that the summer bottom waters will experience the most pronounced acidification, with average pH levels expected to decline from 8.04 to 7.82 and aragonite saturation state (Ω_ar) values decreasing from 2.24 to 1.38 between 2000 and 2100. Additionally, our study indicates that winter acidification trends are also concerning, with pH only slightly higher than in summer bottom waters. The buffering capacity and the DIC:TA ratio play significant roles in determining the rate of future pH and Ω_ar declines. The strong buffering capacity in summer surface waters mitigates the pH decline, while the low DIC:TA ratio results in a rapid drop in Ω_ar.

Keywords: East China sea; Eutrophication; Ocean acidification.