黄河三角洲不同类型盐碱地CO2、CH4和N2O通量特征

Dynamics of CH4, CO2 and N2O Fluxes in Saline-Alkaline Soils of the Yellow River Delta, China

盐碱地作为陆地的重要组成部分,在温室气体排放中的作用不可忽视。为探究滨海盐碱地温室气体排放通量,本研究于2011年10月运用静态暗箱–气相色谱法对黄河三角洲不同类型盐碱地CO2、CH4和N2O日通量进行了原位观测。结果表明,不同植被覆盖与大气界面的CO2、CH4和N2O通量存在明显差异。CO2日排放通量:柽柳群落 >芦苇群落 >翅碱蓬群落,分别为108.2999,84.5160,41.0333 mg·m–2·h–1,而光滩则表现为CO2吸收汇。整体来看,不同植被覆盖CH4日排放通量小,分别是0.0080,–0.0299,0.0212,–0.0068 mg·m–2·h–1,但不同类型盐碱地仍存在差异,光滩和翅碱蓬群落为排放源,柽柳和芦苇群落是吸收汇。不同群落N2O日排放通量的差异性较弱。本试验同时研究了环境因子对不同类型盐碱地上三种温室气体排放通量的影响,相关分析表明,环境因子对光滩温室气体通量没有显著影响,其余三种植被覆盖的温室气体排放通量与不同深度土层温度呈现相关性,说明环境因素对盐碱地温室气体排放作用机制的复杂性。

Salt-affected soils are extensively present and constitute about 7% of total land surface. However, our knowledge about greenhouse gas (GHG) turnover between the atmosphere and the saline soils is very limited. In order to evaluate the potential of GHG consumption in saline soils, we measured gas fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from the soil surface to the atmosphere under saline-alkaline mudflat and various com- munity types in the Yellow River Delta in China. The CO2 emission followed the order: T. chinensis >P. australis >S. salsa >Saline-alkaline mudflat. On the whole, saline-alkaline mudflat and different vegetations acted as CH4 sink be- fore 12:00 and CH4 source after 12:00. However, the four ecosystems acted as N2O source in the whole day. Although measurements of the CO2, CH4, and N2O fluxes were taken simultaneously, CH4 and N2O fluxes were strongly corre- lated with soil temperature at different depths in T. chinensis community. The significantly negative correlations were also found between air and soil temperature and CO2 or CH4 fluxes in S. salsa, N2O fluxes in P. australis. While no sig- nificant correlation was found between greenhouse gases with soil moisture and electrical conductivity. These results probably suggest that factors other than soil temperature, moisture and salinity exerted a larger impact on CO2, CH4 and N2O flux because of its higher spatial and temporal variability.