An estimate of possible use of selected pre-Cenozoic clays from Poland for environmental protection

The paper presents the main results of the study of various Mesozoic (and Upper Carboniferous) clays from southern Poland and their capacities for pollution retention, water isolation and soil restoration. Laboratory testing was performed on 40 clay and claystone samples from 16 quarries in order to identify grain-size and mineral composition (XRD analyses), cation exchange capacity (CEC), filtration coefficient, pH reaction and contents of selected trace elements. The clay series were accumulated in various palaeoenvironmental and palaeoclimatic conditions. They have also had different burial histories. The main component of these rocks is illite and subordinately kaolinite. Smectite (beidellite) and chlorite are usually only accessory minerals. The permeability of the pre-Cenozoic clays is varied, but CEC is very low. The clay deposits are not particularly useful for environmental protection because of scarcity of smectite and due to diagenetic alterations. They are neither a natural sorbent (with the exception of some unexploited Carboniferous bentonitic clays), nor high-quality material for pollution retention. Some of the clays may be useful for water isolation and restoration of the near-surface layer in degraded areas