engleski

Distribution of faecal indicator bacteria and nutrients in Krka river in the region of Krka national park

The distribution of faecal indicator bacteria and viruses in Krka river have been monitored closely over the depth and time for a one year period at different sampling sites along the river pathway from Roški waterfall to Skradin waterfall applying membrane filtration technique. During the summer and dry weather conditions the number of total (TC) and faecal coliform (FC) bacteria in the samples of water was relatively low (TC up to 2x101/100 ml and FC up to 1x101/100 ml). The concentrations of humic substances, as a main component of dissolved organic carbon in water, were low (0.35 – 0.70 mg l-1) and slightly increased over the depth. After summer storm events and during winter wet weather periods the number of bacteria increased in the river over the whole vertical profile (TC up to 2x102/100 ml and FC 3x101/100 ml). Furthermore, in late spring and in autumn unusually high number of heterotrophic plate-count bacteria was observed in the water, especially at 10-m depth. Results of qualitative and quantitative analysis of phytoplankton indicated that in preceding months in the watercourse occurred a high phytoplanktonic activity.

indicator bacteria; faecal coliforms; water pollution; bacterial distributions; humic substances; environmental influences; National park Krka

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