潮白河冲洪积扇典型包气带剖面反硝化强度垂向空间分布规律

以北京市潮白河冲洪积扇区域为研究区,选取两个典型剖面(S6和S8),通过测定不同采样深度(0～10 m)包气带反硝化强度值,分析了包气带反硝化强度的垂向空间分布特征,并识别了包气带反硝化强度垂向分布规律的影响因素.结果表明,典型剖面上各包气带土样的反硝化过程NO_3~--N浓度经历了上升、下降、上升这3个主要阶段; S6和S8剖面包气带反硝化强度取值分别为0. 002 6～0. 018 5 mg·(kg·d)~(-1)和0. 001 7～0. 023 3 mg·(kg·d)~(-1),总体反硝化强度水平较低;剖面垂向空间的反硝化强度总体呈现"S"型变化趋势; S6和S8剖面包气带反硝化强度的主控因素包括黏粒、硝酸盐、亚硝酸盐,并与以ACE和Shannon指数为代表的微生物多样性及反硝化菌亚硝酸盐还原酶基因nir K在一定深度范围内相关性显著.

Vertical Spatial Distribution of Denitrification Intensity in the Vadose Zone of Typical Sections of Chaobai River Alluvial Fan

In this study, the Chaobai River alluvial fan area, Beijing City, was chosen as the study area, and two typical profiles (S6 and S8) were selected to determine the denitrification intensity value of the vadose zone at different sampling depths (0-10 m). The vertical spatial distribution of denitrification in the vadose zone was analyzed, and the influencing factors of the vertical distribution of denitrification strength in the aeration zone were identified. The results showed that the NO₃^--N concentrations in the denitrification process of soil samples in different vadose zones experienced three main stages:rising, falling, and rising. The vadose zone denitrification intensities in S6 and S8 ranged from 0.0026 to 0.0185 mg·(kg·d)^-1 and 0.0017 to 0.0233 mg·(kg·d)^-1, respectively. That the overall denitrification intensity was low. The denitrification intensity of the vertical space showed an "S"-type trend. The main controlling factors for denitrification intensity in S6 and S8 vadose zones included clay, nitrate, and nitrite and showed significant correlations with the diversity of microorganisms, such as the ACE and Shannon indices, and the nitrate reductase (nirK) gene of denitrifying bacteria at a certain depth range.