论文部分内容阅读
选择长江右岸最大支流乌江干流上三座不同时期建造的梯级水库作为研究对象,于2006年4月、7月、10月和2007年1月按水体表层、水深20,40,60和80m分别采集了三座水库的坝前水体分层水样.分析其中水化学特征、溶解无机碳含量及其同位素组成.水库表层水体中溶解无机碳(DIC)及其同位素(δ13CDIC)组成总体特征表现为:DIC浓度夏、秋季较低,冬、春季较高;δ13CDIC值则相反,夏、秋季节偏正,冬、春季节相对偏负.在垂直剖面上,水体中DIC浓度随水深的增加逐渐上升,而δ13CDIC随水体深度增加而偏负.各水库的溶解无机碳同位素组成与天然河流中的差异较大,而接近自然湖泊情况.另外,通过调查不同拦截时间的水库,发现在水库的上层水体中,δ13CDIC随着水库库龄的增长而偏负,水库的营养水平随着库龄的增长而逐渐增高.上述结论表明水坝拦截后河流水化学性质发生了改变,蓄水河流趋向于向湖沼化方向发展;溶解无机碳同位素组成分异在一定程度上可用于示踪水库的演化过程.
Three cascades of reservoirs constructed at different periods on the Wujiang River, the largest tributary of the right bank of the Yangtze River, were selected as research objects. Water samples were collected at the surface water depths of 20, 40, 60 and 80 m in April, July, October and January 2007, respectively The water samples from the three reservoirs were analyzed for water chemistry, dissolved inorganic carbon and their isotopic compositions.The dissolved carbon (DIC) and its isotopic composition (δ13CDIC) in the surface water of the reservoir showed the following characteristics: DIC concentration is lower in summer and autumn, higher in winter and spring; δ13CDIC value is the opposite, the positive summer and autumn seasons, the relatively negative winter and spring seasons.DIC concentration in water gradually increases with the increase of water depth in the vertical section, While δ13CDIC is negative with the increase of water depth.The dissolved inorganic carbon isotopic composition of each reservoir is quite different from that of natural rivers and close to that of natural lakes.In addition, by investigating reservoirs with different interception time, it is found that in the upper water of the reservoir , δ13CDIC is negative with the increase of reservoir age, and the nutrient level of reservoir gradually increases with the increase of the age of the reservoir.The above conclusions show that the chemical properties of river water have changed after interception, It tends to flow towards the development of lakes direction; dissolved inorganic carbon isotopic composition differentiation can be used to some extent in the evolution of the tracer reservoir.