三峡澎溪河高阳平湖碳通量初步分析及不确定性

A preliminary study of carbon balance and the uncertainty for Lake Gaoyang,Pengxi River of the Three Gorges Reservoir

为明确三峡水库支流澎溪河回水区的碳收支特征,以澎溪河高阳平湖水域为研究对象,建立了河道型水库主要路径碳收支估算方法,对高阳平湖从2011年9月至2012年8月一个完整水文周年内主要路径的碳通量进行了收支动态分析.结果表明,2011年9月至2012年8月,澎溪河高阳平湖水域河流输入的碳通量为133548.55 t C,输出的碳通量为125651.82 t C,水-气界面的扩散碳通量为762.56 t C,消落带土-气界面的扩散碳通量为123.74 t C,水中气泡的释放碳通量为0.38 t C,降水输入的碳通量为104.58 t C,全年高阳平湖水域碳的净积累量为7114.63 t C,宏观上呈现碳积累特征;澎溪河高阳平湖水域水体碳素总体上呈现出河道型水库特有的纵向输移特征.高阳平湖水域上游大量碳素的输入及其在高阳平湖水域的滞留可能会是该水域水-气界面温室气体释放的主要来源.尽管总体上高阳平湖全年呈现出碳积累的特点,但一些方法依然存在不确定性(水-气界面扩散碳通量和气泡释放碳通量的时空异质性等),需要更系统、更长期的工作予以验证或改进.

To understanding the carbon budget, our research chose Lake Gaoyang as object and established an estimate method of carbon budget. From September 2011 to August 2012, we analyzed the main path of carbon budget for the Lake Gaoyang in Pengxi River. The main conclusions for the one year are as follows： input carbon fluxes of river transport were 133548.55 t C, output carbon fluxes of river transport were 125651.82 t C, diffusive fluxes of water to air interface were 762.56 t C, diffusive fluxes of waterlevel-fluctuating zone were 123.74 t C, ebullition fluxes were 0.38 t C, input carbon fluxes of precipitation were 104.58 t C, and net accumulation of carbon fluxes of the Lake Gaoyang were 7114.63 t C. It was mainly in the form of dissolved inorganic carbon. The carbon in the water of the Lake Gaoyang in Pengxi River showed the characteristics of longitudinal transport along the river channel. Lots of carbon went into the uplift air and deposited in Lake Gaoyang from upstream. It may be the main source of greenhouse gases on the water to air interface. As a whole, Lake Gaoyang presents the characteristic of carbon accumulation throughout the year, but some methods remains uncertain for the spatial and temporal heterogeneity of water-gas interface diffusion flux and air release flux. We need more systematic and long-term work to verify or modify.