猫跳河流域梯级水库夏-秋季节溶解无机碳（DIC）含量及其同位素组成的分布特征

于2007年7月(夏季)、10月(秋季)2次对猫跳河流域河流-水库水体样品进行了采集,分析其水化学组成特征,溶解无机碳(DIC)含量及其同位素组成,研究了猫跳河流域河流-水库的碳元素地球化学行为,目的是阐明梯级水库拦截后河流的碳元素含量和碳同位素(δ13CDIC)组成的分布特征.水体DIC及其同位素(1δ3CDIC)组成的总体特征为:DIC含量夏季低于秋季,夏季DIC含量为1.35~2.84 mmol/L,平均值为2.12 mmol/L,秋季DIC含量为2.03~3.98 mmol/L,平均值为2.67 mmol/L;1δ3CDIC值则相反,夏季较秋季偏正,其1δ3CDIC值流域夏季为-10.3‰~-5.1‰,平均值是-8.6‰,秋季为-13.0‰~-6.9‰,平均值为-9.0‰,表明夏季藻类光合作用优先富集12C,水体富集13C.夏季水库的DIC含量随着深度的加深而增大,而δ13CDIC值则随着深度的加深而偏负,表明表层水体受藻类生物作用影响较大,下层水体主要受有机质的降解影响.DIC含量从上游至下游呈逐渐降低的趋势,而δ13CDIC值从上游至下游呈逐渐偏负的趋势,表明河流受水坝拦截后河流水化学性质发生了改...

Dissolve Inorganic Carbon and Its Carbon Isotope Composition in Cascade Reservoir of the Maotiao River During Summer and Autumn

Water samples along water column in the front of dams and samples at 0.5 m below surface water from tributary rivers were collected in July and October,2007.The water chemistry, concentrations of dissolve inorganic earbon and its carbon isotopic compositions were determined, in order to investigate the geochemical behavior of carbon in the Maotiao River. This study aimed to understand the variations of the concentrations of dissolved inorganic carbon(DIC)and δ~(13)C_(DIC) during its transport along the cascade reservoirs and river system. The results showed that DIC concentrations in summer were lower than that in autumn. In summer, the DIC concentrations were 1.35-2.84 mmol/L, with an average value of 2.12 mmol/L; and in autumn they fell into 2.03-3.98 mmol/L,with an average value of 2.67 mmol/L.The δ~(13)C_(DIC) in surface water along Maotiao River ranged from -10.3‰ to -5.1‰ in summer, with a value of -8.6‰ in average, and in autumn,δ~(13)C_(DIC) became more negative,and had a range from -13.0‰ to -6.9‰,with an average value of -9.0‰.Generally,DIC in surface water showed a trend to decrease from the upper reaches to lower reaches along Maotiao River,and δ~(13)C_(DIC) gradually became more negative downstream. On the water column, DIC concentrations were higher in hypolimnion, while δ~(13)C_(DIC) had a reverse trend with higher values occurred in epilimnion. The results indicated that the hydrochemistry of river could be significantly changed by river damming processes.As for carbon, reservoir should be an important place for the transformation among the different carbon species.