地球与环境

文章摘要

筑坝对河流水化学和流域风化速率估算的影响——以乌江支流三岔河、猫跳河为例

Impacts of Damming on Riverine Water Chemistry and Chemical Weathering Rate Estimation in Basins——A Case Study from the Sancha River and the Maotiao River

投稿时间：2019-07-12 修订日期：2019-08-27

DOI：10.14050/j.cnki.1672-9250.2019.47.143

中文关键词: 水化学;风化速率;水库;喀斯特;乌江

英文关键词: hydrochemistry;chemical weathering rate;reservoir;karst;Wujiang

基金项目: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）；国家重点研发计划项目（2016YFA0601001）。

作者	单位	E-mail
仇晓龙¹, 王宝利¹, 梁重山², 郎赟超¹, 刘涛泽², 李亚军¹, 肖晶¹	1. 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 2. 中国科学院地球化学研究所环境地球化学国家重点实验室, 贵阳 550081	baoli.wang@tju.edu.cn

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中文摘要:

利用水化学可以估算所在流域的化学风化速率，但筑坝对此的影响目前还不清楚。本研究以西南喀斯特三岔河和猫跳河河流-水库体系为研究对象，季节性调查了其水化学情况，并对其所在流域的岩石风化速率进行了估算，以评估筑坝对此的影响。调查水体的Ca²⁺、Mg²⁺、HCO₃^-、SO₄^2-的平均浓度分别为1 397、429、2 359、832 μmol/L，表明其水化学组成主要受碳酸盐岩风化控制；这四种离子之和（MTDS）在水库中相对稳定且具有明显的季节变化，但河流MTDS变化相对复杂且无明显规律，表明筑坝显著影响了原有河流的水化学。河流筑坝后水流变缓，水深增加，生物作用增强，导致MTDS在水库剖面出现化学分层，而水库底层泄水的发电方式使得大坝下游水化学继承了水库底层水的特征，由此利用坝前坝后水化学数据计算出的化学风化速率差异在20%左右。

英文摘要:

Impacts of damming on River water chemistry and accuracy of estimating chemical weathering rates in basins remain unclear. In order to improve current understanding on this issue, we investigated the water chemistry seasonally and estimated the rock weathering rate of the karst basin of the Sancha River and the Maotiao River. The average concentrations of Ca²⁺, Mg²⁺, HCO₃^- and SO₄^2- were 1 397, 429, 2 359 and 832 μmol/L, respectively, indicating that the chemical composition of water was controlled mainly by the weathering of carbonate rocks. The sum of these four ions (MTDS) in the reservoir was relatively spatially stable but varied seasonally, but MTDS in two rivers were irregular, indicating that the dam did impact the river water chemistry. The dam on rivers decreased the velocity of water flow, increased water depth and biological activity, and such resulted in the stratification of MTDS in the reservoir. Due to deep water discharging for hydropower in the reservoir, the downstream water chemistry inherited characteristics of the bottom water of the reservoir, which led to about 20% difference in chemical weathering rates estimated from the water chemistry of the surface water of the reservoir or the downstream water after the dam.

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