Analysis of urban composite non-point source pollution characteristics and its contribution to river DOM based on EEMs and FT-ICR MS.

Urban composite non-point source (UCNPS) has an increasing degree of influence on the urban receiving waters. However, there remains a dearth of precise techniques to characterize and evaluate the contribution of UCNPS. Therefore, this study developed a source analytical methodology system based fluorescence excitation-emission matrices spectroscopy (EEMs) and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS).Specifically, it utilized parallel factor analysis (PARAFAC), two-dimensional correlation spectroscopy (2D-COS), end-member mixing analysis (EMMA), and non-metric multidimensional scaling (NMDS) to analysis UCNPS pollution characteristics and quantify its contributions to river DOM. The results of its application in typical hilly and plain urban within the Yangtze River Basin, China revealed that road and roof runoff exhibited high aromaticity and humic-like content, and the characteristics of pipe sediment was similar with domestic sewage. The component of Rivers had sequences of changes under rainfall perturbations. But terrestrial humic-like represented the initial input in all cases, and it can provide some indication of UCNPS input. The results of EMMA showed that the contribution of road runoff, roof runoff, pipeline sediment and domestic sewage to river DOM was 9.0 %-36.0 %, 2.6 %-19.1 %, 2.3 %-28.8 % and 5.9 %-25.9 %, respectively, and the specific contribution was mainly affected by rainfall level, regional terrain and drainage system. The methodology system of this study can provide technical support for the traceability and precise control of UCNPS pollution.