Monitoring of fecal contamination in a partly restored urban stream in Seoul, Korea

Abstract

Cheonggye-cheon is a partly restored urban stream located in central Seoul. We monitored fecal contamination using three different fecal indicators, total coliforms (TC), fecal coliforms (FC) and E. coli, to assess differences in each indicator on days of varying weather conditions. Presumptive TC, FC and E. coli colonies were identified by their 16S rRNA sequences. The results showed that enumeration of E. coli provided a better reflection of fecal contamination of the stream than TC and FC. The main sources of contamination were the inflow of fecal-polluted groundwater from the vicinity of a subway line and two inflowing streams. The fecal contamination was worsened on days with heavy rain because untreated sewage from a collecting facility flowed into the stream. Moreover, growth potential of fecal indicator (E. coli) in situ induced by algal exudates was measured. Our results suggest that an appropriate standard based on E. coli rather than TC and FC should be established for improving water quality management strategies of Cheonggye-cheon in the future.

Natural wetlands in protected areas as a key to water quality resilience

“…For water samples, dilutions of 500 μL, 1 mL, and 10 mL of each sample were ltered, followed by plating on culture media, and the volume of 1mL was chosen considering the suggested colony counts according to APHA 9222 (Rice & Baird, 2017), for sediment samples were carried a pretreatment according to the methodology of Young et al (2016) and Craig et al (2002) (Craig et al, 2002;Seo et al, 2016). An amount of 25 g of sediment was placed in sterile glass asks containing 75 mL of 0.1 % peptone water ( 3M, USA), then placed in an orbital shaker for 15 minutes at 250 rpm, centrifuged at 3000 rpm for 15 min, and the supernatant was separated, ltered by a membrane ltration method and followed the same procedure as water samples.…”