• 关键词：二氧化碳分压p(CO₂)  二氧化碳逸出量F(CO₂)  水库  刘家峡  黄河

• 基金项目：国家自然科学基金（No.91547110，51469018，51609118）；国家重点研发计划项目（No.2016YFC0500508）

• 宫辰
• 1. 内蒙古河流与湖泊生态重点实验室, 呼和浩特 010021;2. 内蒙古大学生态与环境学院, 呼和浩特 010021

• 杨现坤
• 广州大学地理科学学院, 广州 510006

• 田明扬
• 1. 内蒙古河流与湖泊生态重点实验室, 呼和浩特 010021;2. 内蒙古大学生态与环境学院, 呼和浩特 010021

• 苏元戎
• 1. 内蒙古河流与湖泊生态重点实验室, 呼和浩特 010021;2. 内蒙古大学生态与环境学院, 呼和浩特 010021

• 李凌宇
• 1. 内蒙古河流与湖泊生态重点实验室, 呼和浩特 010021;2. 内蒙古大学生态与环境学院, 呼和浩特 010021

• 冉立山
• 香港大学地理系, 香港 999077

• 刘少达
• 耶鲁大学林业和环境研究学院, 纽黑文 01642

• 于瑞宏
• 1. 内蒙古河流与湖泊生态重点实验室, 呼和浩特 010021;2. 内蒙古大学生态与环境学院, 呼和浩特 010021

• 胡海珠
• 1. 内蒙古河流与湖泊生态重点实验室, 呼和浩特 010021;2. 内蒙古大学生态与环境学院, 呼和浩特 010021

• 吕喜玺
• 1. 内蒙古河流与湖泊生态重点实验室, 呼和浩特 010021;2. 内蒙古大学生态与环境学院, 呼和浩特 010021;6. 新加坡国立大学地理学院, 新加坡 117570

• 摘要：河流上修建水库改变了自然状态下的水流运动，而且深刻影响着物质传输和交换过程.本文以黄河源区12级梯级水库群末端的刘家峡水库为例，在2016年4、8月和2017年5月进行了3次野外试验，采用Li-7000静态箱法监测了刘家峡水库入库前、库中和出库河道内的二氧化碳分压（p（CO₂））、二氧化碳逸出量（F（CO₂）），并测定了相关水化学因素，包括pH、溶解氧（DO）和水温（T），综合分析了水库碳逸出的暖季时空变化规律及其影响因素.结果表明：在河流流向上，刘家峡水库库区内的p（CO₂）和F（CO₂）（601.6 μatm和85 g·m^-2·a^-1，以C计，下同）均低于入库前水体（670 μatm和328 g·m^-2·a^-1）和出库后水体（680.5 μatm和372 g·m^-2·a^-1），水体的pH变化范围为7.90~8.80，DO变化范围为102%~145%；垂向上，pH为7.81~8.65，DO为82%~140%，从水面至水库库底p（CO₂）的变化范围为617~1087 μatm，p（CO₂）、pH和DO均随水深增加而降低，且8月变化强于4月和5月；水温在垂向上存在明显的分层现象，温度范围为5~25℃.库区内的光合作用降低了水体溶解CO₂的含量，出库水体由于水流波动较大，F（CO₂）明显增加，8月水体的F（CO₂）均低于5月，可能是由于水库中的热分层现象更加显著，进一步促进了浮游植物的生长，对溶解性CO₂的利用增加.通过对世界范围内不同纬度和海拔高度的水库F（CO₂）的统计发现，刘家峡水库的F（CO₂）在温带地区水库的F（CO₂）中呈较低水平，其高海拔的地理位置及梯级水库的拦截作用是重要原因.本研究可为高寒高海拔地区水库的F（CO₂）评估和全球水库碳排放评价提供依据.

• Abstract：The construction of reservoirs on large rivers has changed natural water flow, and profoundly affected the material transport and nutrient exchange. In this paper, the Liujiaxia reservoir, the last of the 12 cascade reservoirs in the headwater region of the Yellow River was chosen as an example to study spatial and temporal variations of CO₂ evasion in warm season. Field investigations were carried out in April, August 2016 and May 2017, respectively. Partial pressure of carbon dioxide (p(CO₂)) and efflux of carbon dioxide (F(CO₂)) were measured using headspace and Li-7000 gas analyzer in the various sites within the reservoir and downstream of the dam. Some relevant hydro-chemical factors, including pH, dissolved oxygen (DO) and temperature (T), were also measured. The temporal and spatial variations of carbon evasion and its influencing factors were investigated. The results indicated that pH value in the water body ranged from 7.90 to 8.80 and DO from 102%~145%. p(CO₂) and F(CO₂) (601.6 μatm and 85 g·m^-2·a^-1) in the reservoir were lower than the water just before entering the reservoir(670 μatm and 328 g·m^-2·a^-1)and after leaving the reservoir (i.e. downstream of the dam) (680.5 μatm and 372 g·m^-2·a^-1), respectively. In the vertical direction, there was a clear stratification phenomenon for water temperature, ranging from 5 to 25℃, 7.81~8.65 for pH and 82%~140% for DO. p(CO₂) from the surface to the bottom of the reservoir fluctuated from 617 to 1087 μatm, pH, DO and p(CO₂) decreased more in August than in April and May. The photosynthesis in the reservoir reduced the amount of dissolved CO₂, but F(CO₂) downstream of the dam significantly increased due to fast river flow. The water F(CO₂) in August was lower than that in May, because of the significant thermal stratification in the reservoir, promoting the growth of phytoplankton and the utilization of dissolved CO₂. Compared with other reservoirs, F(CO₂) from the Liujiaxia reservoir was at a low level in the temperate zone because of its high altitude and the cascade reservoirs in its upper stream. The study provided the basis for the estimation of F(CO₂) in the reservoirs located in the cold and high altitude regions, and for the assessment of the global reservoir carbon emission.

• Key words：p(CO₂)  F(CO₂)  reservoir  Liujiaxia  the Yellow River

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