A test system for the determining of the fate of pesticides in surface water. Protocol and comparison of the performance for parathion of ecocores and micro ecosystems from two sources.

Protocols are described for constructing laboratory micro-ecosystems (MES), incubating them with radiolabelled pesticides and then using a routine test procedure to ascertain the fate of these pesticides in surface water. The performance of fresh ecocores and acclimated MES from two sources was compared. The influence of the duration of the acclimation to room temperature and a light cycle on the fate of parathion was studied. The variation between replicates of MES was less than that between ecocores. The eutrophic ecocores and MES performed similarly, the oligotrophic ecocores transformed parathion faster than the oligotrophic MES. In eutrophic systems, reduction to aminoparathion was much faster than in oligotrophic systems. The sandy oligotrophic MES needed a longer acclimation to laboratory conditions than the eutrophic MES to produce reproducible results. The results of year-to-year experiments were also more reproducible for the eutrophic MES.