北京昆玉河夏季水-气界面CO2通量日变化研究

以昆玉河为例，采用LGR-动态通量箱法，对城市河流夏季水-气界面CO2释放通量进行24h连续监测．结果表明，观测点处水-气界面CO2释放通量具有明显的日变化特征．24h内CO2释放通量在-27．18～12．51mg·m1·h1，平均值-7．28mg·m-2·h-1，昼间平均值为-8．81mg·m-2·h-1，夜间平均值为-4．22mg·m-2·h．24h内水-气界面CO2通量，极大值出现在21：20为12．51mg·mq·h-1，极小值出现在6：20为-27．18mg·m1·h～．在夏季城市河流水-气界面CO2通量受到气温、风速、总磷（TP）、总氮（TN）、总碱度（TA）等因素影响，使城市河流成为大气CO2的碳“汇”之一．

Diurnal Variation of CO2 Flux Across Water-air Interface in Summer in Kunyu River of Beijing

In order to study the greenhouse gases daily emission characteristics of the urban rivers in summer, we take the Kunyu River for example and use the LGR-airtight floating dynamic flux chamber method to ac- complish a 24 h continuous monitoring of CO2 flux across water-air interface. It is indicated that the CO2 flux across water-air interface appears an obvious diurnal variation characteristics. The Kunyu River predominant- ly absorbs CO2 from atmosphere within 24 h, while sometimes it emits CO2 from water into air. The range of CO2 emission flux is --27.18--12.51 mg · m-2·h-1. The 24 h average, diurnal average and nocturnal average of COz fluxes are --7.28 mg·m-2·h-1, --8.81 mg·m-2· h-1 and --4.22 mg·m-2·h-1 , respectively. The maximum 12.51 mg·m-2·h 1 appears at 21：20 while the minimum --27.18 mg·m-2·h-a ap- pears at 6 ： 20. In the summer, the COz flux across water-air interfaee in the urban river is influenced by tem- perature, wind speed, TP, TN, TA and other factors, so as to make the urban river becomes a carbon ＂sink＂ of CO2.