羌塘高原湖水δ^(13)C_(DIC)值特征及影响因素分析  

Characteristics of δ^(13)C_(DIC) value in lakes on Qiangtang Plateau and its affected factors

作　　者：类延斌[1] 姚檀栋[1] 张恩楼[2] Sheng Yongwei 王伟财[1] 李均力 王翔[4] 

机构地区：[1]中国科学院青藏高原研究所青藏高原环境变化与地表过程重点实验室,北京100085 [2]中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室,南京210008 [3]Department of Geography,University of California,Los Angeles,CA 90095-1524 [4]临沂市国土资源局地质环境监测站,临沂276000

出　　处：《湖泊科学》2011年第5期673-680,共8页Journal of Lake Sciences

基　　金：中国科学院知识创新工程重要方向项目(KZCX2-YW-Q09-06-01),中国科学院对外国际合作重点项目(GJHZ0906);国家自然科学基金项目(40810019001)联合资助

摘　　要：湖水溶解无机碳同位素(δ13CDIC)是研究湖泊碳循环的有效手段,其影响因素分析是古湖沼学中重建过去环境的理论基础,但国内关于这一方面的研究却还相对较少.本文研究了羌塘高原24个湖泊水体δ13CDIC值空间分布特征及其影响因素.结果表明,所选湖泊水体δ13CDIC值在-15.0‰至3.2‰之间,平均值为-1.2‰,表现出较高的同位素特征,部分湖泊δ13CDIC值甚至高于水体与大气CO2交换平衡时的同位素值.羌塘高原湖水普遍显碱性并具有较高的碱度,大部分咸水湖泊溶解CO2呈逸出状态,仅有少数淡水或微咸水湖泊以溶解大气CO2为主要特征.封闭湖泊水体DIC浓度和δ13CDIC值要明显高于入流河水,而外流湖泊与河水较为接近.湖水与大气CO2交换程度决定了羌塘高原封闭湖泊δ13CDIC值的高低.由于封闭湖泊DIC滞留时间长,湖水与大气CO2交换程度高,湖水δ13CDIC值比较接近平衡状态.本研究对认识羌塘高原封闭湖泊碳循环过程及沉积物中无机碳同位素环境意义具有重要理论价值.Dissolved inorganic carbon isotope（ δ13 CDIC ） is an important element to reveal the carbon cycle in lake system. Factors influencing the variation of the δ13 CDIC value play an important role in paleolimnological study. However, there were only few stud- ies focusing on the spatial variation of 813CDIC from closed lakes in China. In this study, we showed the characteristics of the δ13 CDEc values in waters of 24 lakes on the Qiangtang Plateau（QTP） and analyzed the affected factors for their spatial variations. The δ13CDIC values in the 24 lake water varied between - 15.0%o to 3.2‰, with an average value of - 1.2%0. Theδ13CDIc values in the closed lakes show high isotopic characteristics, some even higher than the atmospheric isotopic equilibrium value. DIC concen- tration and 813CDIC value in the closed lakes were significantly higher than those in rivers, but there was no significant difference between overflowing lakes and rivers. Although lakes on QTP had high pH value and high alkalinity, the average partial pressure of dissolved CO2 （pCO2 ） in the 24 lakes was several times greater than that of the overlying atmosphere. Gas CO2 exchange between lake water and atmosphere is an important factor influencing the δ13 CDIC value in closed lakes. Due to the high DIC residence time, the long time gas CO2 exchange makes the δ13 CDIC value close to the atmospheric isotopic equilibrium value. For lake water with high pCO2 , degassing of dissolved CO2 in the water makes the δ13CDIC value close to or higher than the atmospheric isotopic equilibrium value. For lake water with low pCO2 , invasion of atmospheric CO2 makes the δ13 CDIC value close to the atmospheric isotopic equilibrium value.

关 键 词：羌塘高原 溶解无机碳 δ13CDIC 湖泊碳循环 古湖沼学 

分 类 号：X524[环境科学与工程—环境工程]