Characterization of drilling waste from shale gas exploration in Central and Eastern Poland.

The purpose of this research was to determine and evaluate the chemical properties of drilling waste from five well sites in Central and Eastern Poland. It was found that spent drilling fluids can contain high values of nickel and mercury (270 and 8.77 mg kg respectively) and can exceed the maximum permissible limits recommended by the EC regulations for safety of soils (75 mg kg for nickel and 1.