Functional Response of a Near-Surface Soil Microbial Community to a Simulated Underground CO2 Storage Leak

Abstract

Understanding the impacts of leaks from geologic carbon sequestration, also known as carbon capture and storage, is key to developing effective strategies for carbon dioxide (CO2) emissions management and mitigation of potential negative effects. Here, we provide the first report on the potential effects of leaks from carbon capture and storage sites on microbial functional groups in surface and near-surface soils. Using a simulated subsurface CO2 storage leak scenario, we demonstrate how CO2 flow upward through the soil column altered both the abundance (DNA) and activity (mRNA) of microbial functional groups mediating carbon and nitrogen transformations. These microbial responses were found to be seasonally dependent and correlated to shifts in atmospheric conditions. While both DNA and mRNA levels were affected by elevated CO2, they did not react equally, suggesting two separate mechanisms for soil microbial community response to high CO2 levels. The results did not always agree with previous studies on elevated atmospheric (rather than subsurface) CO2 using FACE (Free-Air CO2 Enrichment) systems, suggesting that microbial community response to CO2 seepage from the subsurface might differ from its response to atmospheric CO2 increases.

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

“…Similar to the ASGARD results, a previous study during about 20 days of CO 2 injection at the ZERT field site showed no significant CO 2 impact on mcrA abundane (Morales and Holben 2013). However, contrary results were detected especially for natural CO 2 vents with both increasing and decreasing numbers of mcrA genes with increasing CO 2 concentration (Oppermann et al 2010;Frerichs et al 2013).…”

“…In contrast to rather inconsistent results from CO 2 injection studies (Morales and Holben 2013;Fernández-Montiel et al 2015), most previous results from natural CO 2 vents suggest a CO 2 -induced decrease in microbial abundance (e.g. .…”

“…However, less data are available for microbial responses on changing climate parameters during CO 2 -injection. Morales and Holben (2013) for example, described CO 2 -induced alterations in soil microbial community related to seasonal conditions during a CO 2 injection period in summer 2009. They also assume a strong probability that CO 2 impacts might be masked by seasonal variations.…”

Response to nitrogen addition reveals metabolic and ecological strategies of soil bacteria

“…Modern microbiology techniques have given us unprecedented access to the microbial world (Rinke et al., ; Spiro, ), yet soil microbial communities remain poorly understood (Delmont et al., ). While many studies have focused on the diversity or abundance of key populations (Gubry‐Rangin et al., ; Taylor, Zeglin, Wanzek, Myrold, & Bottomley, ; Wei et al., ), fewer have looked at the transcriptional profiles over time (Morales & Holben, ; Nicol, Leininger, Schleper, & Prosser, ), and even less have done so for multiple groups at the same time (Brenzinger, Dörsch, & Braker, ; Liu, Mørkved, Frostegård, & Bakken, ; Liu, Frostegård, & Bakken, ). This is particularly true of organisms involved in nitrogen (N) cycling in soils.…”

Developments since 2005 in understanding potential environmental impacts of CO2 leakage from geological storage

“…A low cost multispectral system was also able to identify plant stress but as with the hyperspectral work, unable to unequivocally define the cause of that stress (Hogan et al, 2012a;Hogan et al, 2012b). Enhanced CO 2 in the soil at ZERT also affected both the abundance and activity of microbial functional groups mediating C and N transformations (Morales and Holben, 2013). However, these effects were not equal suggesting there may be two separate mechanisms.…”