地球与环境

文章摘要

乌江梯级筑坝对河流碳酸氢根的影响机制

Effects of Cascade Dams on Bicarbonate Contents in the Wujiang River

投稿时间：2019-08-22 修订日期：2019-09-24

DOI：10.14050/j.cnki.1672-9250.2019.47.146

中文关键词: 梯级筑坝;碳同位素;光合作用;呼吸作用;乌江

英文关键词: cascade dams;carbon isotope;photosynthesis;respiration;Wujiang River

基金项目:国家重点研发计划项目（2016YFA0601001）国家自然科学基金委—贵州喀斯特科学研究中心联合项目（U1612441）。

作者	单位	E-mail
孟凡勇, 肖晶, 仇晓龙, 王宝利, 郎赟超	天津大学表层地球系统科学研究院天津市环渤海地球关键带科学与可持续发展重点实验室, 天津 300072	baoli.wang@tju.edu.cn

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中文摘要:

梯级筑坝显著改变了河流碳的生物地球化学循环。为了了解梯级筑坝对河流HCO₃^-的影响，本文对乌江中上游梯级水库的HCO₃^-浓度、溶解无机碳同位素（δ¹³C_DIC）及相关的环境参数进行了长时间跨度的分析。乌江中上游梯级水库-河流体系HCO₃^-浓度为1 421.54～3 387.52 μmol/L，平均值为2 363.21 μmol/L；δ¹³C_DIC为-10.66‰～-4.52‰，平均值为-8.54‰；梯级筑坝导致河流具有下游HCO₃^-浓度升高的变化趋势。河流筑坝发电，易形成峡谷型深水水库。碳同位素证据和相关性分析表明，上层的光合作用和下层的呼吸作用成为控制发电水库碳循环的主要因素。这导致HCO₃^-浓度在水库剖面上呈现出由上层至下层逐渐增高的变化规律，再加上水库底层泄水的发电方式，最终导致梯级筑坝河流下游HCO₃^-浓度逐渐升高。本研究将加深梯级筑坝对河流碳循环影响机理的理解。

英文摘要:

Cascade dams changed the biogeochemical cycle of river carbon significantly. In order to understand the impact of cascade dams on the content of HCO₃^- in river water, the concentration of HCO₃^-, the isotope of dissolved inorganic carbon(δ¹³C_DIC)and related environmental parameters of cascade reservoirs in the middle and upper reaches of the Wujiang River were analyzed over a long period of time in this study. The HCO₃^- concentration varied from 1 421.54 to 3 387.52 μmol/L with an average of 2 363.21 μmol/L, and δ¹³C_DIC ranged from -10.66‰ to -4.52‰ with an average of -8.54‰ in the cascade reservoir-river system of the upper and middle reaches of the Wujiang River. Cascade dams lead increasing of HCO₃^- concentration in the downstream of the river. The dam for power generation resulted in the development of canyon and deep reservoir. Carbon isotope evidence and correlation analysis showed that photosynthesis in the surface water and respiration in the bottom water were the main factors controlling the carbon cycle in reservoirs. As a result, the HCO₃^- concentration in reservoirs increased gradually from the surface layer to the bottom layer. In addition, the power generation mode of water discharge at the bottom layer of the reservoir finally led to the gradual increase of HCO₃^- concentration in the downstream of the river. This study deepened the understanding on effects of cascade dams on the river carbon cycle.

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