Seasonal divergence in dissolved-carbon concentration and export along a cascade-dammed subtropical river continuum: A case study of the
7 affiliations
- 1Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China; National Field Scientific Observation and Research Station of Dongting Lake Wetland Ecosystem in Hunan Province, Changsha, 410125, China
- 2Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China; National Field Scientific Observation and Research Station of Dongting Lake Wetland Ecosystem in Hunan Province, Changsha, 410125, China; Corresponding authors at: Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
- 3Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
- 4Climate Center of Hunan Province, Changsha, 410118, China
- 5College of Geographic Science, Hunan Normal University, Changsha, 410081, China
- 6Changsha General Survey of Natural Resources Center, China Geological Survey, Changsha, 410600, China
- 7Department of Biological Sciences, the University of Québec at Montreal, Montreal, QC, H3C 3P8, Canada
Abstract
Study region: The Zijiang River is a subtropical monsoonal tributary of the middle Yangtze River, China, characterized by intensive cascade-reservoir regulation along its mainstem. Study focus: We focused on four successive cascade dams and the five longitudinal locations they define (D1–D5), with D1 as the upstream reference and D2–D5 as successive dam-regulated reaches. We examined how hydrological seasonality interacts with repeated cascade regulation to shape DOC and DIC sources, concentrations, and export using seasonal observations integrated with isotope, statistical, and discharge-conditioned analyses. New hydrological insights for the region: DOC and DIC displayed a seasonal reversal, with higher DOC in flood season and higher DIC in non-flood season. Yet export timing diverged: in 2023/24, flood-season water carried 63.7–77.7% of annual DOC export, whereas non-flood season carried 57.9–69.6% of DIC export. Plankton-associated DOC dominated D1–D3, then shifted towards mixed plankton–soil contributions in D4–D5. DIC retained a carbonate-weathering background, while soil-CO₂ contribution increased from D3 downstream. Cascade damming was associated with both carbon pools through distinct environmental pathways. These results show that carbon budgets in cascade rivers must resolve season, dam sequence, source composition and in-river processing rather than rely on concentration snapshots.
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BibTeX
@article{xu2026seasonal,
title = {{Seasonal divergence in dissolved-carbon concentration and export along a cascade-dammed subtropical river continuum: A case study of the}},
author = {Wentao Xu and Yu Cui and Zhengmiao Deng and Hao Qu and Lijie Duan and Cicheng Zhang and Zhitao Huo and Yuan Zhao and Feng Li and Liyan Wang and Tao Wang and Changhui Peng and Yonghong Xie},
journal = {Journal of Hydrology: Regional Studies},
year = {2026},
month = oct,
doi = {10.1016/j.ejrh.2026.104114},
url = {https://doi.org/10.1016/j.ejrh.2026.104114},
note = {CC BY},
}
RIS
TY - JOUR
TI - Seasonal divergence in dissolved-carbon concentration and export along a cascade-dammed subtropical river continuum: A case study of the
AU - Wentao Xu
AU - Yu Cui
AU - Zhengmiao Deng
AU - Hao Qu
AU - Lijie Duan
AU - Cicheng Zhang
AU - Zhitao Huo
AU - Yuan Zhao
AU - Feng Li
AU - Liyan Wang
AU - Tao Wang
AU - Changhui Peng
AU - Yonghong Xie
PY - 2026
DA - 2026/10/30
JO - Journal of Hydrology: Regional Studies
DO - 10.1016/j.ejrh.2026.104114
UR - https://doi.org/10.1016/j.ejrh.2026.104114
AB - Study region: The Zijiang River is a subtropical monsoonal tributary of the middle Yangtze River, China, characterized by intensive cascade-reservoir regulation along its mainstem. Study focus: We focused on four successive cascade dams and the five longitudinal locations they define (D1–D5), with D1 as the upstream reference and D2–D5 as successive dam-regulated reaches. We examined how hydrological seasonality interacts with repeated cascade regulation to shape DOC and DIC sources, concentrations, and export using seasonal observations integrated with isotope, statistical, and discharge-conditioned analyses. New hydrological insights for the region: DOC and DIC displayed a seasonal reversal, with higher DOC in flood season and higher DIC in non-flood season. Yet export timing diverged: in 2023/24, flood-season water carried 63.7–77.7% of annual DOC export, whereas non-flood season carried 57.9–69.6% of DIC export. Plankton-associated DOC dominated D1–D3, then shifted towards mixed plankton–soil contributions in D4–D5. DIC retained a carbonate-weathering background, while soil-CO₂ contribution increased from D3 downstream. Cascade damming was associated with both carbon pools through distinct environmental pathways. These results show that carbon budgets in cascade rivers must resolve season, dam sequence, source composition and in-river processing rather than rely on concentration snapshots.
SN - 2214-5818
ER -