IMPACT OF A SHIP PASSAGE ON BACTERIA LEVELS AND SUSPENDED SEDIMENT CHARACTERISTICS IN THE BUFFALO RIVER, NEW-YORK

Ship traffic in freshwater rivers may impact water quality by resuspen ding contaminated bottom sediment. Water samples were analyzed from tw o different depths at three sites across a transect of the Buffalo Riv er, NY, before and after passage of a lake-going ship. Samples From al l sites were analyzed for fecal coliform (FC), heterotrophic plate cou nt (HPC), and total suspended solids (TSS). The levels of all test par ameters increased immediately after the ship passed with the largest i ncreases observed at mid-channel sites. Epifluorescent direct counts o f mid-channel samples showed that the bacteria in the water column inc reased significantly (p < 0.001) at both 1 and 4 m below the surface a nd were positively correlated with TSS (r = 0.84). Particle size distr ibution in the upper water column was determined by automated image an alysis. The median particle size class, by volume, before and after th e ship passed was 48.9-56.6 mu m and 366.5-391 mu m, respectively. A f ew large flocculated particles accounted for most of the volume of the resuspended sediment. Resuspension of flocculated, bacteria-laden par ticles affects bacterial transport dynamics in riverine systems. The c haracteristics of flocculated sediments in suspension therefore should be considered in water quality modeling. Copyright (C) 1996 Elsevier Science Ltd