中文摘要：

为更加清晰地认识无机碳在岩溶水库水体中的循环转化过程,2013年7月初对位于岩溶区的广西五里峡水库沿流程方向不同地点不同深度水体进行现场监测.结果表明：1研究区水体水化学主要受碳酸盐平衡体系控制,水化学类型为HCO3-Ca＋Mg型.2水体溶解无机碳（dissolved inorganic carbon,DIC）含量及其同位素组成δ^13DIC分布特征：沿流程方向从库尾到坝前同一深度不同取样点DIC含量呈减小趋势（DIC（平均）：1.03～0.78 mmol·L^-1）,δ^13DIC则逐渐变重（δ^13DIC（平均）：-10.21‰～-6.62‰）.沿垂直方向从表层向库底DIC含量呈增加趋势（DIC（平均）：0.86～1.05 mmol·L^-1）,δ^13DIC则逐渐变轻（δ^13DIC（平均）：-7.88‰～-13.39‰）.分析认为：1碳酸盐岩溶解沉淀过程对研究区水体DIC含量及δ^13DIC的影响有限或被其它过程平抑.2研究区水体存在热分层现象,其通过影响水库不同部位、不同深度水生生物新陈代谢的方向及强度、有机质分解强度等对水体DIC及δ^13DIC产生影响,使之出现前述变化趋势.

英文摘要：

To gain more knowledge on the transformation process of dissolved inorganic carbon in a karst reservoir,in situ monitoring,sampling and lab experiments of water columns were carried out at various sampling sites along the flow line in Wulixia Reservoir,Guangxi,China during early July,2013. Results showed that： 1 The hydrochemical characteristics of study areas were controlled by the carbonate equilibrium system and the hydrochemical type of all water samples was HCO3-Ca ＋ Mg. 2 The DIC concentration decreased gradually（DIC（Average）： from 1.03 to 0.78 mmol·L^-1） and the δ13CDICincreased gradually（δ13CDIC（Average）： from-10.21‰to- 6. 62‰） from the reservoir end area to dam area. Meanwhile,with the depth increase in water column,the DIC concentration increased gradually（DIC（Average）： from 0.86 to 1.05 mmol·L^-1） and the δ13CDICdecreased gradually（δ13CDIC（Average）： from-7.88‰to- 13. 39‰） from the surface to the bottom of the reservoir. Possible reasons for these research results were found as follows：1 Dissolution-precipitation process of carbonate substance could be inhibited by other processes such as biogeochemical processes,which played little role in δ13CDICvariations. 2 Thermal stratification existed in the study areas which could influence the distribution of DIC and δ13CDICby affecting the distribution of plankton and its orientation and strength of metabolism process,and the extent of organic matter decomposition,and so on.