 over time within the water (Wat.), sediment (Sed.) and vegetation (Veg.). The vertical bar of a sampling point indicates the range of duplicate samples. The horizontal line shows the background number of the target before adding the spike. For backround counts of the targets (see [Tables 0](#T0){ref-type="table"}, [0](#T0){ref-type="table"}). BS---unvegetated mesocosm and BSM---vegetated mesocosm.](fpubh-00-00000-g0000){#F0}  ![The mean number (N~t~/N~0~) of 