A glass vessel device with water volume of 20 L was constructed for fa
st testing of the fate of a chemical in freshwater watercourse environ
ment. The dynamic system consisted of natural water with throughflow o
f 4.5 mL min(-1) and bottom sediment from a clean oligohumic lake in C
entral Finland. Duckweed (Lemna sp.) as plant material, lake mussel (A
nodonta piscinalis) and crucian carp (Carassius carassius) as test ani
mals were included in the test device. Tetrachloroguaiacol (TeCG) was
dissolved at start to water to make 2 mu g L(-1) concentration. The sa
me concentration of TeCG was maintained in inflow water. After static
and dynamic pre-tests, a dynamic four weeks test at 15 degrees C was r
un with natural water taken in winter. Then, two dynamic four weeks ex
periments in three parallel devices with water taken in summer (15 deg
rees C) and in autumn (10 degrees C) were done. Concentration of TeCG
in outflow water and its partition between sediment and water came to
an equilibrium. Contents in mussel and fish reached no equilibria duri
ng the tests. Six chlorophenolic metabolites of TeCG were identified,
but most of the TeCG had reacted to nonidentified degradation products
. The degradation rate of TeCG was more dependent on the time of year
of water sampling than on the test temperature.