Leachables definition

What is the difference between Extractables and Leachables The following definitions are taken directly from PQRI [43]. 

Results of models for the Tournemire shales are reported in Table 4. These models were based upon the mineralogical and CEC data presented in Tables 1 and 2 the calculated cation exchange selectivity coefficients and the concentrations of leachable Cl present in the rocks. Preliminary selectivity coefficients (Ac(Mg/Na) and Kc Ca./ Na) close to 3 and 4 respectively) have been derived from aqueous extraction experiments. They are in rather good agreement with literature data (Baeyens Bradbury 1994), and are mainly related to the illite and inter-stratified illite/smectite contents. The leachable Cl has been extracted with pure water at a liquid/solid ratio of 10mlg. It is clear that the Tournemire porewater cannot be definitively described with the data available. The porewater is of Na-Cl-(HCO ) type, with a low salinity, equivalent to a total dissolved... 

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