Fig. 5. Light absorption at 254 nm in the percolate collected from different micro suction cups at pH 4.5 and 8.0 in Steps 4 and 5 of the percolation experiment (for conditions refer to the Materials and Methods section and Table 3). Absorption is plotted relative to the absorption of the initial solution of Step 4 containing dissolved organic carbon (DOC) (A₀). Volumes are given in multiples of the pore volume (V₀) of the respective cup.