广州市城市湿地CH_4通量特征研究

Methane Flux from Urban Wetland in the Haizhu Lake

通过静态箱-气相色谱法对广州市海珠湖湿地在2013年12月至2014年11期间的CH4通量季节性变化以及相关环境因子进行研究。结果表明:CH4的通量季节性变化明显,美人蕉、野芋、蓝花草湿地CH4通量最大值集中在5月,CH4通量的季节强弱表现为:夏季>冬季。三者的年平均通量分别为0.33、0.20、0.064 mg·m-2·h-1,三种湿地植物的CH4排放强弱比较为:美人蕉>蓝花草>野芋。植物群落、温度、水力条件、土壤湿度是影响城市湿地CH4通量的主要因子,高植株能够促进湿地释放CH4,高温能够促使城市湿地排放更多的CH4,高水位通过限制土壤呼吸以减少CH4排放,高湿度的土壤则能抑制土壤CH4的扩散。

In the research, enclosed static chamber-gas chromatograph techniques were conducted to analyze the CH4 flux from urban wetland from December 2013 to November 2014. The fields were located in Haizhu Lake, one of the most typical urban wetlands in Guangzhou. The analyses contained seasonal variations in the CH4 fluxes during different seasons as well as the environmental factors, including temperature, pressure and moisture of the soil, biomass and height of the wetland plants. The CH4 fluxes are mainly discussed in this paper. Measurements were taken in wetlands of different hydraulic condition and different plants. The result showed that the fluxes of CH4 of Canna indica, Colocasia tonoimo and Aphelandra Ruellia wetlands peaked in May. The seasonal variation of the fluxes of CH4 was in the order of summerwinter. The average fluxes of CH4 was in the order of Canna indicaAphelandra RuelliaColocasia tonoimo, the fluxes of which are 0.33, 0.20, 0.064 mg·m-2·h-1, respectively. The temperature and soil moisture were the key factors affecting the variation of the fluxes of CH4. The temperature was positively correlated to the CH4 fluxes and there was a negative correlation between the moisture of the soil and the CH4 fluxes. Moreover, the plants in high height can promote the emission of the CH4 from the wetlands. In comparison of other wetlands, less released from the urban in Haizhu Lake, indicating that the urban wetlands are weak sources of CH4.