Dispersal and fate of coliphages in the River Saar

The dispersal of coliphages was analysed quantitatively in longitudinal profiles of the partially canalized River Saar. The numbers of coliphages ranged between 0 and 2380 PFU (plaque-forming units)/ml in the water and between 0 and 2550 PFU/g in the sediments, depending on the degree of fecal pollution. In canalized parts the phages were found mainly in the sediments, whereas in non-canalized parts they prevailed in the water phase (Fig. 3). Determinations performed at municipal sewage water outfalls revealed that in the canalized part most of the phages precipitated to the sediment on a water course of only about 250 m (Fig. 5). In the non-canalized part of the River Saar, sediments were not contaminated to this extent, since phages rather remained in the water, due to high current velocities (Fig. 5). According to these results coliphages are, just like some fecal bacteria, closely associated with particles. They are rapidly inactivated in the sediment and water (inactivation rates: 0.12 to 0.66 d-1).