dc.description.abstract | Abstract: Simple, automated methods are required for rapid detection of wastewater contamination
in urban recreational water. The activity of the enzyme b-D-galactosidase (GAL) can rapidly (<2 h)
be measured by field instruments, or a fully automated instrument, and was evaluated as a potential
surrogate parameter for estimating the level of fecal contamination in urban waters. The GAL-activity
in rivers, affected by combined sewer overflows, increased significantly during heavy rainfall, and the
increase in GAL-activity correlated well with the increase in fecal indicator bacteria. The GAL activity
in human feces (n = 14) was high (mean activity 7 b 107 ppb MU/hour) and stable (1 LOG10 variation),
while the numbers of Escherichia coli and intestinal enterococci varied by >5 LOG10. Furthermore, the
GAL-activity per gram feces from birds, sheep and cattle was 2–3 LOG10 lower than the activity from
human feces, indicating that high GAL-activity in water may reflect human fecal pollution more than
the total fecal pollution. The rapid method can only be used to quantify high levels of human fecal
pollution, corresponding to about 0.1 mg human feces/liter (or 103 E. coli/100 mL), since below this
limit GAL-activity from non-fecal environmental sources may interfere. | nb_NO |