Persistent degradation products of halogenated blowing agents and refrigerants in the environment

TZW carries out a precipitation monitoring on TFA

In the project, an analysis and evaluation of the overall environmental impact of (new) halogenated substances and their degradation products is conducted in Germany and in the EU. At the focus of the TZW-devised measuring programme is the prominent drinking water contaminant trifluoroacetate (TFA). Precipitation samples are collected at eight different precipitation measuring points of Germany’s weather service, DWD, and analyzed for TFA. By this, the extent of atmospheric deposition to the overall TFA pollution can be estimated.

There are many different anthropogenic sources of trifluoroacetate (TFA) in drinking water resources: industrial discharges, waste water treatment plants, agriculture and not least, the photochemical degradation of certain propellants and refrigerants, and subsequent pollution by atmospherically formed TFA via precipitation. This illustrates that serious conflicts may arise between the individual substances and effective countermeasures are only possible if the individual inputs of the possible substance sources locally are known.

The main task of TZW in this project is to design and implement precipitation monitoring to quantify how much atmospheric deposition contributes as a nationwide critical diffuse source of TFA. Daily precipitation samples are collected over a period of 24 months at eight different measurement stations of the German weather service. These are used to create precipitation-equivalent monthly mixed samples for each site in the lab, which are analysed for TFA. The results are also used to show any local and seasonal pollution trends and can help to derive a TFA contamination function in groundwater resources and a type of background concentration via atmospheric contamination. Additional TFA sources can only be identified and solution strategies established using this information. The results of this work package are contrasted in the further project stages with those from the modelling of propellant and refrigerant consumption volumes, and information from (eco)toxicological impact tests. They can then be used directly to determine various future scenarios and incorporate them into substance regulation.