贵州乌江渡水库沉积速率及碳氮埋藏通量估算

我国西南地区峡谷型梯级水库沉积物的碳汇效应对全球碳循环有着重要意义。为了探明该区域水库的碳汇强度,本研究选择乌江流域的乌江渡水库作为研究对象,于2015年5月对水库沉积物进行采样,并利用210Pbex核素计年技术,结合沉积物碳氮分析,估算乌江渡水库的碳埋藏量。结果表明:乌江渡水库沉积物平均沉积速率为0.155g/(cm~2·a),TOC沉降通量为70.85g/(m~2·a),堆积通量为29.14g/(m~2·a);TN沉降通量为8.22g/(m~2·a),堆积通量为2.79g/(m~2·a)。乌江渡水库沉积物年均TOC总埋藏通量为1.39×10~9g/a,其中82%来自水库内部光合作用形成的有机质。因此,依据保守的估算,乌江渡水库沉积物的净碳汇通量为23.9g/(m~2·a),保存的净碳汇量为1.1×10~9g/a。研究结果表明水库沉积物是一个重要的碳汇。

The Sedimentation Rate and Burial Fluxes of Carbon and Nitrogen in Wujiangdu Reservoir, Guizhou, China

The burial of carbon in reservoir sediments in southwestern China is of great significance to the global carbon cycle as a carbon sink. In order to calculate the magnitude of the carbon sink,the contents of TOC, IC and TN in sediments of Wujiangdu reservoir in Wujiang River basin were determined, and the sedimentation rate was estimated on basis of activity of ²¹⁰Pb_ex in this paper. Results show that the average sedimentation rate was 0.155 g/(cm²·a), and deposition and accumulation fluxes of organic carbon were 70.85 g/(m²·a) and 29.14 g/(m²·a), respectively. TN shared a similar vertical distribution with TOC, with deposition and accumulation fluxes of 8.22 g/(m²·a) and 2.79 g/(m²·a), respectively. The annualtotal burial flux of TOC was 1.39×10⁹ g/a, while 82% comes from organic matter formed by photosynthesis in the reservoir. Therefore, the net flux of carbon sink was 23.9 g/(m²·a), and the net carbon sink in Wujiangdu reservoir is 1.1×10⁹ g/a, conservatively. Result here suggests that sediments in reservoirs in southwestern China are a significant carbon sink.