This study aimed to examine the pollution characteristics of rainfall runoff as well as the runoff scouring effect and pollution traceability in adjacent new and old urban areas. The sampling and monitoring of rainfall runoff for different rainfall underlying surfaces were conducted for roads, green spaces, roofs, and a food market. The concentration of chemical oxygen demand (COD) and nutrients in the rainfall runoff of the market area was higher than that measured for roads, green spaces, and roofs. The initial scouring effect of each underlying surface was obvious during rainstorms, and 30% of the runoff transported nearly 50% of the pollutants. Further, 30% of the runoff transported about 30% of the pollutants under moderate and heavy rain conditions, and the overall initial scouring effect was not obvious. The results of this study showed that, as a considered underlying surface area, the market and possibly other similar service facilities had a significant impact on the calculation of runoff pollution load, and these should be included in the research scope of rainfall runoff and the impact of underlying surfaces. The purpose of this study was to provide reliable and practical information for water pollution prevention and control, especially for pollution prevention and control of rainfall runoff in areas where new and old urban parts of cities exist side by side.

Dissolved organic matter (DOM) is generally the dominant carbon pool in freshwater lakes and plays a vital role in the regional or even global carbon cycle. In recent years, steppe lakes have been subject to two stressors: eutrophication and abnormally high concentrations of organic matter. However, little is known about the sources and composition of the organic matter. In this study, carbon/nitrogen (C/N) ratios and three-dimensional excitation–emission matrix (3DEEM) fluorescence spectroscopy were adopted to identify the sources and composition of DOM in Hulun Lake, a large shallow steppe lake. The physicochemical and water quality parameters of Hulun Lake and three inflow rivers, Crulen River, Orshen River and Hailar River, were also investigated. The results showed that visible fulvic-like fluorescence (peak C) and tryptophan-like substances (peak T) were the main components of the DOM. The C/N atomic ratios and spectral characteristics of the DOM suggested that approximately 82% of the DOM in Lake Hulun is derived from terrigenous material. The results underscore that it is necessary to devote more research attention to terrestrial inputs into steppe lakes.