【摘要】 发源于云贵高原上的乌江是长江流域的重要支流之一。乌江流域喀斯特地貌广泛发育,是中国南方典型的喀斯特河流。以枯水季节乌江流域水体中的实测温度、溶解氧、碱度和pH值等理化参数为依据,探讨了乌江流域河道水体的CO₂分压(P_CO2)与河流"呼吸"通量的变化规律。乌江流域枯水季节河道水体P_CO2,介于291.3～1 530μatm之间,平均值为949.3μatm,约为大气的3倍,各支流样点的平均值为992.4μatm,大于干流平均值902.6μatm,由此推断乌江流域干支流河道在枯季是大气CO₂的"源"。受各游段流域特征以及人类活动的影响,干支流河道水体P_CO2表现出明显的空间差异。水体P_CO2与溶解氧的相关关系不显著,说明河道内有机质的异养呼吸不是喀斯特乌江流域枯季水体中溶解无机碳的主要来源,其河道水体中高P_CO2成因复杂。P_CO2的上述分布规律是流域支流汇入、地下水以及河道水体有机质氧化分解等共同作用的结果。更多还原

【Abstract】 Wujiang River,originating from Yungui Plateau,is an important tributary of the Yangtze River. It is a typical karst river in southern China with karst landform developed considerably. The partial pres- sure of CO₂ (P_CO2) and the"breath"flux of the stream water in Wujiang basin were discussed based on the field riverine data of certain physical and chemical parameters, such as temperature （T）, dissolved oxygen （DO） ,alkalinity （ALK） and pH in the stream water. The value of P_CO2 was at the range of the data from 291.3μatm to 1 530μatm in stream water and the mean value was 949.3μatm,which was 3 times more than that of atmosphere ambience. And the mean value of P_CO2 was 992.4μatm in the tributaries, which was slightly more than that of 902.6μatm in mainstream. Thus it can be deduced that the Wujiang stream water is a source for CO₂ in atmosphere in low flow season. The obvious spatial variation of P_CO2 in the ma- instream was caused by the characteristics of basin reaches and human activities. The unapparent negative relationship between P_CO2 and DO in low flow season showed that heterotrophic respiration in the riverine water was not the main source of the riverine DIC （dissolved inorganic carbon） in Wujiang River. The sources of Wujiang riverine DIC were considerably complicated for there were likely many riverine DIC sources in the stream water. The spatial distribution of P_CO2 was the result of the import of karst surface water and groundwater as well as the oxidation and decomposition of organic matter.更多还原