Response of soil bacterial community and geochemical parameters to cyclic groundwater‐level oscillations in laboratory columns

Groundwater‐level oscillations change geochemical conditions, C cycling processes, and bacterial community composition, and these changes may vary vertically with depth in a soil. In this study, soil column experiments were conducted to explore variations in soil bacterial community composition and its associated geochemical parameters to rapid short‐term cyclic groundwater‐level oscillations driven by natural fluctuations (NF) and rainfall infiltration (RI), and the results are compared with a quasistatic (QS) column. Water saturation patterns in vadose and oscillated zones, and O2 level patterns, soil total organic C (TOC) removal rates, and soil bacterial community composition in vadose, oscillated, and saturated zones were evaluated. Results showed that water saturation and O2 level oscillated with groundwater level in NF and RI columns. Total organic C removal rates in RI column were the highest across vadose (∼38.4%), oscillated (∼35.8%), and saturated (∼35.2%) zones. Deltaproteobacteria, which were significantly correlated with TOC removal (p