河滨修复湿地不同植物配置对甲烷排放的影响

为了探讨河滨修复湿地在不同条件下CH₄的排放规律及降低CH₄排放的调控途径,以自行设计和建造的河滨湿地为研究对象,对植物种类配置及植株密度进行人为调控,运用静态箱-气相色谱法测定CH₄排放通量. 结果表明:①CH₄排放通量具有明显的季节性变化规律,其中夏季最大,占全年CH₄总排放量的50%以上；冬季最小,低于全年CH₄总排放量的5%. ②植物种植会明显增加CH₄的排放,不同植物类型通过改变w(SOC)(SOC为土壤有机碳)、气体传输机制以及产CH₄菌群落来改变湿地的CH₄排放,4种供试植物中,通气组织较发达的芦苇和水葱湿地CH₄排放通量分别为(1.98±0.78)和(1.41±0.58)mg/(m2·h),显著低于黄菖蒲的(6.77±1.92)mg/(m2·h). ③提高植株密度可以通过增加输气通道和提高w(SOC)来促进湿地CH₄排放,黄菖蒲植株密度为150株/m2时,CH₄平均排放通量为(10.31±2.56)mg/(m2·h),比植株密度为56株/m2时高出近30%. 因此,建议在新建和修复河滨湿地的设计和建造过程中,种植芦苇和水葱等通气组织较发达的植物,并在满足湿地修复、生态环境保护和景观营造等要求的前提下,适当控制植株密度,以有效减少CH₄排放. 

Influence of Plant Configuration on CH4 Emissions from Restored Riparian Wetland

Abstract: Field research using static chamber-gas chromatography was conducted to investigate the pattern of methane (CH₄) emissions from a created riverine wetland. The objective of the study was to estimate CH₄ emissions with different vegetation types and plant densities, and to determine the environmental parameters controlling CH₄ emissions from created and restored riparian wetlands. The results showed that created riparian wetland had the highest CH₄ emission flux in summer, accounting for more than 50%, and the lowest flux in winter, less than 5%. The presence of plants significantly enhanced CH₄ emissions. Through altering soil organic carbon content, the gas transmission mechanism and the methanogen community, different plant species changed wetland CH₄ emissions. CH₄ emission rates of aerenchyma-developed Phragmites australis and Scirpus validus were (1.98±0.78) and (1.41±0.58) mg/(m²·h), respectively, lower than Iris pseudacorus (6.77±1.92) mg/(m²·h). Higher plant density could strengthen CH₄ emissions by increasing gas channels and soil organic carbon content. When I. pseudacorus density was 150 stem/m², its average CH₄ emission flux was (10.31±2.56) mg/(m²·h), which was 30% higher than that for 56 stem/m². Thus, in the process of the design and construction of created and restored wetland, planting species with aerenchyma, such as P. australis and S. validus, and controlling plant density could effectively reduce CH₄ emissions.