Will carbon capture plants contaminate drinking water? Biodegradation potential of nitramines in lake water

Sammendrag

There is a potential risk associated with (potentially) carcinogenic nitrosamines (NSAs) and nitramines (NAs) that can form in the air from amines escaping amine-based carbon capture plants (CCP). These are very soluble molecules that can end up in drinking water sources such as lakes and groundwater basins. In Norway, a drinking water threshold of 4 ng/L has been set for the sum of NSAs and NAs. A dynamic modelling tool is under development to guide the industry and regulators to ensure that the safety limit will not be exceeded. In the model, the major removal mechanism for NSAs is photodegradation, while biodegradation is the dominant removal mechanisms for NAs. Thus, reliable biodegradation rates for NAs are needed to realistically simulate future levels in the water compartment. A modified OECD 309 simulation test for biodegradation in surface water was used to assess biodegradation rates of three representative nitramines. Caffein was used as positive reference control. The study site was a drinking water lake located in the vicinity of a planned CO2 capture plant. Water and sediment were collected at different seasons, and the tests were performed with and without added sediment. The three nitramines were added either separately or together to the test bottles, and primary degradation was measured by LC-MS/MS compared to the abiotic control. The biodegradation rates varied between experiments. However, the difference in degradation rates was consistent with (monoethanol)-nitramine (MEA) being the most rapidly degradable, 2-methyl-2-(nitramine)-1-propanol (AMP) being moderately degradable and N-nitropiperazine (NIPZ) having limited degradation after 60 days. Adding sediment to the surface water increased biodegradation rates. The effect of different modifications of the test set up (with/without sediment and single vs mixture of test substance) will be presented and discussed.