Answer:
Fracturing fluids such as return fluids represent a potential risk to groundwater and surface water, due to the existing connection with
aquifera recharge zones.
During drilling in the fracking it is possible that there is water contamination due to accidental spillages of contaminants, for example in the process of cementing the casing or integrity problems of the casing may result
in the migration of thermogenic methane gas into the water.
Another source of contamination arises from the possibility that a hydraulic fracture is connected to the surface, since a fracture hydraulic can intercept a natural fracture for example a geological fault
When fracturing substance migration can be promoted toxic substances present in the subsoil, such as mercury, radio, lead and arsenic, which may increase the occurrence of chemical reactions and the creation of new polluting substances.