FECAL CONTAMINATION AND INTERRELATIONSHIPS AMONG INDICATOR MICROORGANISMS AFTER RAINFALL EVENTS FROM UPSTREAM OF THE SUMIDA RIVER TO THE DAIBA COASTAL AREA

Abstract

 Coastal recreational areas in Tokyo such as Odaiba Seaside Park have been polluted by combined sewer overflows (CSOs). Surface water sampling was conducted from upstream of the Sumida River to the Odaiba coastal area after rainfall events in October and November 2017. Four types of fecal indicator bacteria (E. coli, Total coliform, Fecal coliform and Enterococcus) and two types of potential viral indicators (F-specific bacteriophage and Somatic coliphage) were analyzed. Immediately after rainfall events, concentrations of fecal bacteria increased by around two orders of magnitude, while an order of magnitude for bacteriophages. Fate of E. coli changed according to the difference in salinity. High correlations were found among four types of fecal bacteria. Cluster analysis results on indicator microorganisms by their fate characteristics indicated that they were categorized into three groups consisting of a subgroup of bacteria and two subgroups of each bacteriophage.