Long-term CO₂injection and its impact on near-surface soil microbiology

Abstract

Impacts of long-term CO 2 exposure on environmental processes and microbial populations of near surface soils are poorly understood. This near-surface long-term CO 2 injection study demonstrated that soil microbiology and geochemistry is influenced more by seasonal parameters than elevated CO 2 . Soil samples were taken during a three-year field experiment including sampling campaigns before, during and after 24 months of continuous CO 2 injection. CO 2 concentrations within CO 2 -injected plots increased up to 23% during the injection period. No CO 2 impacts on geochemistry were detected over time. In addition, CO 2 -exposed samples did not show significant changes in microbial CO 2 and CH 4 turnover rates compared to reference samples. Likewise, no significant CO 2 -induced variations were detected for the abundance of Bacteria, Archaea (16S rDNA) and gene copy numbers of the mcrA gene, Crenarchaeota and amoA gene. The majority (75-95%) of the bacterial sequences were assigned into five phyla: Firmicutes, Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes. The majority of the archaeal sequences (85-100%) were assigned to the thaumarchaeotal cluster I.1b (soil group). Univariate and multivariate statistical as well as principal component analyses (PCA) showed no significant CO 2 -induced variation. Instead, seasonal impacts especially temperature and precipitation were detected.3

Bacterial community response to a preindustrial‐to‐future CO2 gradient is limited and soil specific in Texas Prairie grassland

“…Several studies have considered climatic factors such as temperature and precipitation as important drivers of seasonal dynamics affecting soil bacterial communities (Cruz‐Martínez et al, ; Gwosdz et al, ; Lauber, Ramirez, Aanderud, Lennon, & Fierer, ; Morales & Holben, ). These studies demonstrated significant impact of seasonal variation on bacterial community structure and composition.…”