崇明东滩湿地植被分布对沉积物暗碳固定的影响

Effect of vegetation distribution on dark carbon fixation of sediments in Chongming Dongtan wetland

研究河口湿地暗碳固定对于全面认识和科学评估河口湿地碳汇潜力具有重要科学意义。以崇明东滩为典型研究区域,利用14C同位素标记法并结合分子生物学技术,研究不同湿地植被分布对沉积物暗碳固定的影响及其关键环境控制因子。结果表明:崇明东滩湿地光滩、芦苇、互花米草区域沉积物的年平均暗碳固定速率分别为(1.27±0.66)、(0.88±0.40)和(1.37±0.63)mmol/(m^(2)·d);河口湿地沉积物暗碳固定具有显著的季节差异,其中夏季沉积物暗碳固定速率显著上升,但极端高温对暗碳固定具有一定抑制作用;互花米草植被促进了沉积物中的暗碳固定,而芦苇区沉积物暗碳固定速率相对光滩则有所降低;不同植被通过调节NH_(4)^(+)、Fe^(3+)、S^(2-)以及关键功能基因(cbbL、cbbM)丰度进而影响沉积物中的暗碳固定。研究结果为准确评估河口湿地碳汇潜力及影响机制提供理论借鉴与数据参考。

The study of dark carbon fixation in estuarine wetlands is of great scientific significance for the comprehensive understanding and scientific assessment of the carbon sink potential of estuarine wetlands.Taking Chongming Dongtan as a typical study area,the effects of different wetland vegetation distributions on sediment dark carbon fixation and its key environmental control factors were studied using 14C isotope labeling technology combined with molecular biology research methods.The results showed that:the annual mean values of sediment dark carbon fixation rates in mudflat,Phragmites australis,and Spartina alterniflora wetlands were(1.27±0.66),(0.88±0.40),(1.37±0.63)mmol/(m^(2)·d)C,respectively;there were significant seasonal differences in sediment dark carbon fixation in estuarine wetlands,in which the dark carbon fixation rates increased significantly in summer,but were inhibited by extremely high temperatures;the dark carbon fixation in sediments was promoted by Spartina alterniflora,while that in the Phragmites australis area was reduced relative to the mudflat;different vegetation influenced the dark carbon fixation in the sediment by regulating the NH_(4)^(+),Fe^(3+),S^(2-)and the abundance of functional genes(cbbL and cbbM).The results provide a theoretical reference to accurately assess the carbon sink potential and the influence mechanisms of the estuarine wetlands.