Urban surface runoff is an important non-point pollution source, and research on contamination characteristics of runoff is urgent for improving urban aquatic environment quality. Typical cities along the downstream Yangtze River, Wuxi and Nanjing, were selected in this study, and runoff samples from various underlying surfaces were collected to investigate contamination characteristics of heavy metals and dissolved organic matter (DOM). The results indicated that the concentration of heavy metals have exceed water quality standards in underlying surfaces partly, the decreasing order of metal contaminations was Zn > Cu > Pb > Sb > Cd. Contamination characteristics of surface runoff were found to exhibit significant differences, and arterial traffic exhibited the severe contamination of both heavy metals and DOM. Spectral characteristics indicated that the structure of DOM exhibited significant differences in various underlying surfaces, and DOM humification levels in Wuxi showed the following decreasing orderg the aquatic environment quality in downstream Yangtze River.Clarifying the current situation of regional water pollutants and the relationship between pollutants and pollution sources is considered essential for managing the water environment. Water quality identification index (WQI), cluster analysis (CA), positive matrix factorization (PMF), and stable isotope analysis in R (SIAR) were employed to interpret a large and complex water quality data set of the Qinhuai River catchment generated during 2015 to 2019 to monitor of 11 parameters at 29 different sampling sites. WQI analysis indicated that water quality in Qinhuai River catchment is considered to have "moderate pollution," and an improving trend of water quality was observed at the interannual scale. TN was the most deteriorated of all pollution parameters. CA and PMF results on the spatial scale revealed that sampling sites located at downtown of Nanjing and Lishui District or Jangling University town were highly polluted due to the sewage from domestic sewage and business service sewage (28.88%) as well as industrial wastewater (27.43%), while sampling sites located at Hushu Street Administrative District, Ergan River, and Sangan River were slightly polluted by rural domestic wastewater and garbage (28.79%), and agricultural non-point source pollution (24.3%). The middle-lower reaches (Jiangning Development Zone and Moling Street) and middle reaches (Lukou Street Administrative District) were moderately polluted by industrial wastewater (27.25%), sewage from domestic wastewater and business service wastewater (31.62%) as well as inner sources (24.76%). The SIAR results showed that NO3--N was the main nitrogen form, and the NO3--N mainly originated from sewage (61%) and soil (34%) in the Yuntaishan River sub-catchment. These results will aid in the development of measures required to control water pollution in river catchments.In this study, indoor simulation experiments were performed to elucidate the effects of migration and transformation of dissolving organic matter (DOM) during the decay of algal blooms. Based on ultraviolet-visible spectra (UV-vis) and excitation-emission matrix spectroscopy (EEMs), spectral characterizations of dissolved organic matter (DOM) in overlying water were evaluated with analyses of the physical and chemical indexes, variation in dissolved organic carbon (DOC), and variation in dissolved inorganic carbon (DIC). Results showed that at the early stage of decay, a large amount of organic matter was released, and dissolved oxygen (DO) decreased sharply. With the extension of reaction time, DOC gradually changed into DIC, which further changed the oxidation-reduction and acid-base characteristics of the water. UV-vis spectra showed that a large amount of DOM was released with high aromaticity and a high degree of humification, and the released DOM was gradually degraded. 4-Hydroxytamoxifen With the application of parallel 5) with Fn355; and C2 was significantly positively correlated (P less then 0.05) with DOC and Fn280; C3 was positively correlated (P less then 0.05) with FI, BIX and βα. The variation trend of these spectral parameters was consistent with that of DOM components. In summary, with the analyses of water quality characteristics and spectral characteristics of DOM in overlying water during algae blooms decaying process, it was expected that our results could contribute to the further exploration of the dynamic migration and transformation of lake DOM and the changes of carbon cycling.To clarify the impact of water quality and social activity in the Baiyangdian wetland on the biological community, the change characteristics of bacterial, fungal, and archaeal communities in different areas of the Dian District were studied. Samples were collected at the entrance of Fuhe District (NBB), tourist areas with frequent human social activities (NBD), residential breeding areas (NBX), and village sparse areas (NBN). The physical and chemical characteristics and biological communities of the samples were evaluated. The results of the study show that the COD concentration of organic pollutants in the NBB was 12.35 mg·L-1, and the total nitrogen concentration was 10.12 mg·L-1, that the concentration was highest. Moreover, the water quality in NBD and NBX was better than that of NBB. The NBN area exhibited the best water quality, with COD and total nitrogen concentration values of 6.9 mg·L-1 and 1.82 mg·L-1, respectively. Many types of NBB bacteria were recorded, with a diversity index of 5.86, and NBN the water, and the microbial community structure has changed significantly. The contents of organic matter, nitrogen, and phosphorus in water were increased and the microbial community structures were changed significantly by the increase of both external and internal pollution.Increased loads of biogenic and terrestrial natural organic matter into freshwater lakes are projected to be a major consequence of global climate change and cyanobacterial blooms. In this study, the effects of phytoplankton-derived organic matter (POM) and terrestrial humic acid (HA) on the activity, composition, and function of the microbial community in Lake Taihu sediments were investigated. Fluorescent spectra demonstrated that POM with high chemodiversity was composed of labile protein-like components (50%) and recalcitrant humic-like components (50%), while humic-like substances accounted for 97% of HA. Over two-month periods, the organic carbon mineralization in sediments was enhanced owing to increasing NOM concentrations; however, the carbon consumption in POM-amended sediments was significantly higher than that in sediments amended with the same concentrations of HA. Analysis of extracellular polymeric substances indicated that NOM input improved the microbial secretion of proteins and polysaccharides, increasing the aggregation and stability of the microbial community.