Fig. 4. Sorption isotherms for sorption of 1,2,4-trichlorobenzene (1,2,4-TCB) by K+– and Mg2+–saturated Pahokee peat, Houghton muck, and Brookston loam, the Webster A and B horizon soils, and the fractions with OM removed. Isotherm labels with different letters (a–f) represent statistical difference at p < 0.05.