城市绿地温室气体通量监测与减排研究

采用LGR-密闭式动态通量箱法对城市绿地生态系统温室气体(CO₂、CH₄)通量的日变化、季节变化特征及其影响因子等进行了较为系统的研究。城市绿地花草CO₂通量有明显的日变化和季节变化特征,白天通量值为负,是CO₂的净吸收汇;夜晚为正值,是CO₂的净释放源;7:00左右由源转为汇,17:00左右由汇转为源,不同花卉24 h总通量有正负2种结果。冬季草坪作为源的时间延长,而作为汇的时间缩短。光强和温度是影响CO₂通量日变化和季节变化的主要因素。城市绿地CH₄通量较小,不足以对温室气体总量产生显著影响。从减少温室气体排放的角度对城市绿地花草的选择提出了建议。

Study of Flux Monitoring and Emission Reduction of Urban Greenbelts Greenhouse Gases

This paper makes a systematic research on the emission/absorption fluxes of two primary types of greenhouse gases (CO₂, CH₄) of urban greenbelts with airtight dynamic flux chamber method. The diurnal and seasonal variation of the greenhouse gases fluxes and the influence of environmental factors on them are discussed,while a comparison of different types of urban greenbelts (grasses and flowers) are made. CO₂ fluxes exhibited an obvious diurnal and seasonal variation. The fluxes are negative during the daytime and the greenbelts are sinks of CO₂. At night,the values are positive and the greenbelts are sources of CO₂. The flux values changed from positive to negative at about 7 AM,and from negative to positive at about 17 PM. The 24 hours total value of the flux is positive or negative. During winter,the grassland has a longer positive period and shorter negative period. The diurnal variation of CO₂ fluxes correlated principally with light intensity and temperature inside chamber. The CH₄ fluxes of urban greenbelts are very little so that there is little influence on the total amount of the greenhouse gases. Some suggestions are given to the selection of grass and flowers of urban greenbelts in the respect of reducing the emission fluxes of greenhouse gases.