Groundwater contamination by fluorinated aromatics: Benzotrifluoride and its derivatives

Benzotrifluoride (BTF) and its derivatives (BTFs) were found in the groundwater of the Veneto region (Italy) as a result of industrial contamination dating back to the 1970s. In the first survey, BTF and 6 BTFs were identified, out of which 4-chloro-3nitrobenzotrifluoride (3N4CBTF) was the only quantified analyte (concentration up to 1 mg L^-1) and was used to trace the contamination plume. A survey carried out in 2008-2009 after the development of more suitable analytical procedures based on GC-MS, allowed to determine 4 new derivatives in addition to BTF and BTFs previously identified, with the most abundant compounds found at concentrations up to 11.9 μg L^-1 and 7.2 μg L^-1 respectively. A systematic monitoring program for the evaluation of persistence and distribution of fluorinated compounds was carried out in 2013-2018, and new data about the BTF and BTFs occurrence and distribution were gathered. Additional BTFs were identified and high concentrations of individual BTFs were recorded near the contamination source (e.g. 20.3 μg L^-1 of 4-chloro-3-nitrobenzotrifluoride in 2017) as well as at large distance (e.g. 22.4 μg L^-1 of 3N4CBTF and 12.5 μg L^-1 of 4-chlorobenzotrifluoride in 2018). The results of BTFs monitoring campaigns carried out in 2008-2009 and 2017-2018 are compared and related to the historical data to assess the overall occurrence and distribution of BTFs contamination over a time range of ∼40 years. Remarkably, BTFs were still found (2018) at μg L^-1 range. Spatial and temporal occurrence of BTF and BTFs in groundwater has been assessed for the first time.