Bacterial Response from Exposure to Selected Aliphatic Nitramines

Abstract

Currently the most promising method for capturing anthropogenic produced carbon dioxide (CO2) from suitable point sources is the technique using amines in Post-combustion CO2 Capture (PCC). However, the use of amine is found associated with formation of the potent harmful and stable compound group of aliphatic nitramines. The toxic effect of these aliphatic nitramines, including species of different trophic levels, must be assessed, prior to any large-scale implementation of PCC. In this present study bacterial response from acute exposure to the two nitramines monoethanolnitramine (MEA-NO2) and dimethylnitramine (DMA-NO2) have been assessed. This has been done by looking for effects in the rate of aerobic respiration by measuring the oxygen consumption using O2 Sensor Dish®Reader system (Presens), and in community-level metabolic profiling including 31-different ecological relevant carbon substrates using the Ecoplates™ (BIOLOG). Samples of both natural bacterial community (lake-water) and pure bacterial culture have been included in this study. The nitramines have been quantified using LC-MS. Results suggest MEA-NO2 to inhibit rate of O2 consumption in natural lake-water bacterial community at concentrations > 4 mg L-1. No such effect was found for pure culture of Bacillus subtilis, neither from exposure to MEA-NO2 nor to DMA-NO2. Moreover, the two nitramines are found to induce slight shifts in the metabolic profile of natural lake-water bacterial communities. Challenges associated with working with highly dynamic natural bacterial communities lead to the recommendation of additional testing to be performed in order to obtain a conclusive picture of bacterial response to the nitramines. The levels of nitramines found in this study to affect bacteria are 1000 fold higher than what is currently estimated to be expected from the emissions of a PCC plant (worst-case scenario). Final environmental concentrations, following years of operation is however dependent on the effect of biogeochemical processes (e.g. soil sorption and biodegradation) taking place at any given site.