Chromophoric Dissolved Organic Matter Fluctuation Assessment in an Urban River

To investigate the compositions and spatio-temporal changes of chromophoric dissolved organic matter (CDOM) in a typical urban river in Taihu Basin, China, that has been treated with series of water quality mitigation measures, 180 water samples were collected from November 2011 to October 2012 and analyzed with fluorescence excitation-emission matrices combined with parallel factor analysis (EEMs-PARAFAC). Three humic-like components (C1, C2, and C4) and two protein-like components (C3 and C5) were identified. Fluorescent intensity showed more apparent temporal changes than spatial changes, and humic-like substances were dominant. The C3, C4, and C5 components decreased from November 2011 to October 2012, indicating effective CDOM removal by the water quality mitigation measures. Significant positive correlations were found between fluorescent components (C3 and C5) and nutritional factors including TN, NH4+-N, and NO3--N. Furthermore, changes of fluorescent components (C2) were found to be related to microbial phosphatase activities. The application of EEMs-PARAFAC presents a promising approach to track the compositions and spatio-temporal changes of CDOM in urban rivers.