EQUILIBRIUM PARTITIONING THEORY OVERESTIMATES CHLOROBENZENE CONCENTRATIONS IN SEDIMENT POREWATER FROM LAKE KETELMEER, THE NETHERLANDS

Concentrations of di, and trichlorobenzenes were determined in porewat er and sediment of a sediment core from lake Ketelmeer, the Netherland s. Average in-situ partition coefficients for di, and trichlorobenzene s (log K-oc) ranged from 4.3 +/- 0.2 for 1,2-dichlorobenzene to 5.0 +/ - 0.2 for 1,2,4-trichlorobenzene. Concentrations of di-and trichlorobe nzenes in porewater were 1 to 2 orders of magnitude lower than calcula ted from the sediment data using literature partition coefficients. In -situ partition coefficients differed from literature values for parti tion coefficients obtained in lab experiments by a factor of 8 to 160. Assuming that the low concentrations in porewater can be attributed t o the presence of a slow desorbing fraction it can be calculated that for most compounds studied more than 95% of the measured sediment conc entration was present in the slow desorbing fraction. (C) 1997 Elsevie r Science Ltd.