三峡水库夏季干流、支流(草堂河)水体的二氧化碳分压及扩散通量

Partial pressure and diffusion flux of dissolved carbon dioxide in the main stream of the Three Gorge Reservoir and the Caotang River in summer

2013年5-7月对三峡水库库区干流及支流草堂河水体CO_2分压(pco_2)进行走航观测.结果表明:夏季草堂河表层pco_2为15.8~226.4 Pa,三峡水库库区干流表层pco_2为198.8~261.1 Pa.对支流草堂河剖面监测发现,表层pco_2最低为15.8 Pa,随着深度增加,pco_2快速增加,在水深5 m后逐渐稳定,最大值为294.2 Pa.通过计算,支流草堂河在5,6,7月的CO_2通量分别为16.46,-4.91和30.85 mmol·m^(-2)·d^(-1),库区干流CO_2通量为45.83 mmol·m^(-2)·d^(-1).因此,三峡库区干流表现为CO_2的"源",支流草堂河CO_2释放远小于库区干流,6月份表现为"汇".

From May 2013 to July 2013, monthly cruise investigation was conducted to study the partial pressure of dissolved carbon dioxide （pco2） in the main stream of the Three Gorge Reservoir and its tributary, the Caotang River. The results show that pco2 in the surface water of the Caotang River varied from 15.8 to 226.4 Pa, and 198.8 to 261.1 Pa for the main stream of the Three Gorge Reservoir. Along the water column of the Caotang River, the lowest value of pco2 in surface water was 15.8 Pa, and increased rapidly with the depth, and kept stable below 5 m with a maximum value of 294.2 Pa. According to calculations, emission fluxes of CO2 in the Caotang River in the period of investigation were about 16.46, 4.91 and 30.85 mmol m^-2·d^-1, respectively. In the main stream of the Three Gorge Reservoir, this flux was 48.54 mmol·m^-2·d^-1. The results show that the main stream of the Three Gorge Reservoir is a source for atmospheric CO2, and the tributary Caotang River emits less CO2 than the main stream, even a sink for atmospheric CO2 on June.