Chemical analyses of spring waters and factor analysis to monitor the functioning of a karstic system. The role of precipitations regimen and anthropic pressures.

An approach is presented to study the functioning of a karstic massif and assess the adverse effects of the anthropogenic pressure by monitoring some water chemical and physical parameters of its main springs. The approach has been applied to the Sette Comuni Plateau (Veneto Region, Italy) hosting a well developed karstic system, whose aquifer presents high vulnerability and undergoes a relevant anthropogenic pressure. The Oliero springs, amongst the largest karstic springs in Europe, are the main water output of the plateau. Electrical conductivity, pH, dissolved O(2), hardness, alkalinity, chemical oxygen demand, total suspended solids, ionic species (NH(4)(+), NO(3)(-), NO(2)(-), PO(4)(3-), SO(4)(2-), Cl(-), F(-)), elements (Cr(III), Cr(VI), Mn, Fe, Ni, Cu, Zn, As, Cd, Hg, Pb), and some chlorinated solvents were monitored for one year. This study presents the application of a factor analysis on the water parameters enabling the identification of the dominant chemical and biological processes and pollution sources affecting the karstic system. Results show four factors which are interpreted as karstification, photosynthesis, storm flow pollution and anions. Finally, by associating metals, chemical oxygen demand and total suspended solids with the amount of rainfall in the 48 h before samplings, further detailed information to the fast response of the aquifer to precipitation events was detected and interpreted according to the factor analysis results. The proposed approach, by providing information on the functioning of the aquifer, may help the management of the karstic plateau and is easily adaptable to similar environments.

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.