ISSN:
1573-5117
Keywords:
Danube River
;
large river
;
bacteria
;
ectoenzyme
;
sewage
;
wastewater
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract In an attempt to assess the influence of tertiary-treated sewage influx on bacterial metabolism in the Danube River, bacterial abundance, ectoenzymatic activity, faecal coliforms, faecal streptococci, chlorophyll a (chl a), concentrations of dissolved (DOC) and total organic carbon (TOC) and inorganic nutrients were measured upstream of the sewage influx and compared with sampling sites downstream. Additional samples were taken near the outlet of the sewage treatment plant. Bacterial abundance as determined by epifluorescence microscopy was compared with plate counts of total heterotrophic bacteria. Significantly higher values were obtained at the stations downstream from the sewage influx only for faecal coliforms and faecal streptococci, for glucuronidase activity and bacterial biovolume. All the other parameters were not significantly different from values obtained at the upstream sampling site. Strong seasonal dependence was detectable for nitrate with high concentrations during the winter (≈ 250 µM) and low concentrations during summer (≈ 100 µM). A distinct spring phytoplankton bloom was noticeable in the river reaching chl a concentrations of ≈ 70 µg 1−1; during the remaining seasons chl a concentrations were 〈20 µg 1−1. Highly significant correlations were found between faecal coliform counts and glucuronidase activity. C:N:P ratios of 13.9:10.7:1 (for the upstream station) and 11.7:9.2:1 (for the downstream stations) of dissolved nutrients are rather low indicating severe carbon limitation of bacterioplankton. Based on our results we conclude that the heterotrophic bacterial community is not significantly effected by the input of treated sewage but faecal contamination is readily detectable over a comparatively long reach of 30 km.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00143751
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