Using Synchronous Fluorescence Technique as a Water Quality Monitoring Tool for an Urban River Jin Hur & Soon-Jin Hwang & Jae-Ki Shin Received: 4 September 2007 / Accepted: 30 December 2007 / Published online: 13 January 2008 # Springer Science + Business Media B.V. 2007 Abstract The development of a monitoring tool for predicting water quality and tracing pollution sources are important for the management of sustainable aquatic ecosystems in urban areas. In this study, synchronous fluorescence technique was applied to 18 sampling sites of a typical urban watershed in Korea, some of which are directly affected by the effluent from a wastewater treatment plant (WWTP), to investigate the capability of the technique for biochemical oxygen demand (BOD) prediction and source discrimination. Sampling was conducted three times at the same sites during the low flow period between October and November, 2005. Protein-like fluorescence intensities of the samples showed a positive linear relationship with the BOD values (Spearman’ s rho=0.90, p <0.0001). The BOD predic- tion capability was superior to other monitoring tools such as UV absorption and conductivity measure- ments particularly for the upstream sites from the WWTP, which ranged from 0.0 to 5.0 mg/l as BOD. The protein-like fluorescence and a ratio of protein- like/fulvic-like fluorescence were suggested as good fluorescence signatures to discriminate different sour- ces of dissolved organic matter (DOM). The samples collected from four different DOM source regions including upstream sites from the WWTP, down- stream sites, discharge from a reservoir, and head- water were distinguished from one another by varying ranges of the two selected fluorescence signatures. Our results suggest that the synchronous fluorescence technique has the potential to be developed into a real-time water quality management tool for the comprehensive monitoring of urban rivers. Keywords Water quality monitoring . BOD . Source discrimination . Fluorescence measurement . Urban rivers 1 Introduction The development of real-time in-situ monitoring techniques is needed to cope with the abrupt deterioration of water quality of natural waters as well as to manage sustainable aquatic ecosystems in a timely and proper manner. Although the traditional water quality parameter, biochemical oxygen demand (BOD), has been widely accepted as an indicator for water pollution, the problem lies in the difficulty Water Air Soil Pollut (2008) 191:231–243 DOI 10.1007/s11270-008-9620-4 J. Hur (*) Department of Earth and Environmental Sciences, Sejong University, Seoul 143-747, South Korea e-mail: jinhur@sejong.ac.kr S.-J. Hwang Department of Environmental Science, Konkuk University, Seoul 143-701, South Korea J.-K. Shin Korea Institute of Water and Environment, Korea Water Resources Corporation, Daejeon 305-730, South Korea