SORPTION OF DISSOLVED ORGANIC-CARBON BY CERAMIC P-80 SUCTION CUPS

Comparison is made between the chemical composition of acid soil solutions percolated through new, acid-washed ceramic P 80 suction ups, and old, over 3 years field-equilibrated suction cups with respect to quantitative and qualitative changes of dissolved organic carbon (DOC). While new suction cups sorb DOC in significant amounts with hydrophobic constituents preferred, field-equilibrated suction cups alter DOC neither in concentration nor in composition. But at changes of DOC concentrations a percolation volume of 300 ml is necessary for reaching equilibrium. It is, therefore, concluded that field-equilibrated ceramic P 80 suction cups can be used for collecting DOC from mineral B and C horizons of acid forest soils, where DOC concentrations remain constant. In contrast, the suction cups investigated are unsuitable for collecting A horizon solutions, which show greater variations in DOC concentration.