In order to explore the vertical distribution characteristics and influence mechanism of organic carbon in the deep water reservoir, taking the southwest karst hinterland reservoir (Pingzhai Reservoir) as case study, water samples were collected at different points during thermodynamic stratification and mixing periods, using mathematical statistics, correlation analysis, relative water column stability (RWCS), to analyze the influence of thermal conditions and hydrodynamic differences on the spatiotemporal and cross-sectional distribution on total organic carbon (TOC). The results show that the thermocline is present in spring, summer and autumn, and the thermocline thickness varies by season. TOC concentration is 0.44–5.65 mg/L, and the annual mean value is 2.16±0.99 mg/L. The seasonal variation pattern of TOC concentration is summer>winter>spring>autumn. There is the seasonal difference of the response between TOC and water environment in Pingzhai Reservoir. Exogenous carbon storage in summer, autumn rainfall dilution, microbial decomposition and sediment release in winter, and algae propagation, biological carbon pump effect in spring are the main causes of the seasonal change of TOC concentration. The fluctuation amplitude of TOC and physicochemical factor profiles in different deep water points are mainly driven by three different hydraulic characteristics. RWCS mainly affects the sedimentation rate of substances such as organic carbon, which results in the difference of TOC concentration and physicochemical factor profile distribution.

为探究有机碳在深水型水库中的垂向分布特征及影响机制, 以西南喀斯特腹地平寨水库为研究对象, 在水体热力分层期间和混合期间采集不同点位和不同水层的水样, 采用数理统计、相关分析和相对水柱稳定性(RWCS)分析等方法, 分析深水型水库热力状况以及水动力差异对总有机碳(TOC)的时空及剖面分布特征的影响。结果表明, 在春季、夏季和秋季3个深水采样点均存在温跃层, 且温跃层厚度因季节而异; TOC浓度变化范围为0.44~5.65 mg/L, 全年均值为2.16±0.99 mg/L, TOC浓度的季节变化特征为夏季>冬季>春季>秋季。平寨水库TOC浓度对水环境的响应存在季节性差异, 夏季外源碳素入库, 秋季降雨稀释, 冬季微生物分解和沉积物再释放以及春季藻类繁殖和生物碳泵效应是导致TOC浓度季节变化的主要原因。不同深水点的TOC浓度及理化因子剖面波动幅度主要受控于3个不同水力特征驱动的水域。RWCS主要影响有机碳等物质的沉降速率, 从而导致TOC浓度和理化因子剖面分布的差异。