Biotransformation in water and soil of nitrosamines and nitramines potentially generated from amine-based CO₂ capture technology

Nitrosamines (NSAs) and nitramines (NAs) are identified as possible degradation products from amine-based post-combustion CO₂-capture (PCCC). Selected NSAs and NAs were subjected to aerobic and anaerobic biodegradation studies. In a screening study with 20 μg/L NSAs and NAs at 20 °C, only NSAs and NAs containing hydroxyl groups (alkanol compounds) exhibited aerobic biotransformation >10% after incubation in 28 days. Extending the biodegradation period to 56 days resulted in ≥80% biotransformation of the examined alkanol NSAs and NAs at 20 °C. Biotransformation (20 °C; 56 days) of the NSA NDELA at different concentrations (1–100 μg/L) did not differ significantly, but both water sources and temperatures affected biotransformation of the tested compounds. Anaerobic biotransformation (20 °C; 56 days) occurred rapidly  with alkanol NSAs and NAs, but not with alkyl compounds. Interestingly, 1st order rate coefficients and half-lives indicated comparable or even faster anaerobic than aerobic biotransformation at the same temperature. Predictions of biotransformation pathways suggested that the -OH substituent of alkanol NSAs and NAs was more susceptible to degradation than nitroso- and nitro-substituents.