[Analysis of Rainfall Runoff Pollution and Pollution Load Estimation for Urban Communities in a Highly Urbanized Region].

The Taihu Lake plain is a highly urbanized region in China with many water-related environmental problems. Although point-source pollution has been effectively controlled by government legislation, urban surface runoff pollution is still a major issue. Different types of urban communities were selected for rainfall runoff experiments. According to the monitoring data of rainfall events, multiple methods were used to analyze the characteristics of surface runoff pollution and estimate the pollution load for different types of communities. The results indicated that surface runoff from urban communities reduced the river water quality. Certain degrees of the 'first flush' effect occurred in different types of urban communities. The surface runoff pollution in the commercial residential community was weaker than that in commercial and private residential communities; however, the first flush occurred more frequently in the commercial residential community. Holding back 30% of the surface runoff could effectively improve the runoff water quality in commercial and private residential communities as well as the commercial residential community with restaurants. In the commercial residential community, 25% of surface runoff should be held to improve runoff water quality effectively. The loads of pollutants, especially nitrogen and phosphorus, in urban communities in the Taihu Lake basin were higher than those in other regions in China. This research can assist with the reduction of surface runoff pollution in highly urbanized communities.

[Characteristics of Stable Isotopes in Precipitation and Their Moisture Sources in Mengzi Region, Southern Yunnan].

The δD and δ¹8O values in precpitation have disciplinary variations, and they have close connections with meteorological parameters and moisture sources. Based on the continuously collected precipitation samples in Mengzi from Jan. 2009 to Dec. 2011, the reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF) and the National Centre for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR), and the Hybrid Single-Particle Lagrangian Integrated Trajectory for 4.8 (HYSPLIT_4.8) model, we analyzed the variations of δD and δ¹8O in precipitation at synoptic scale in Mengzi, and the relations between δ¹8O in precipitation and air temperature, δ¹8O in precipitation and amount, δ¹8O in precipitation and wind speed, δ¹8O in precipitation and moisture sources. The results showed that the variations of δD and δ¹8O values in precipitation exhibited remarkable seasonal variability. The stable isotopic values in precipitation were higher during dry season than those during wet season. The relations between δ¹8O in precipitation and air temperature, δ¹8O in precipitation and amount indicated significant negative correlations. However, it exhibited significant positive correlation between precipitation δ¹8O and wind speed at different pressure levels (300 hPa, 500 hPa, 700 hPa, and 800 hPa), and this result indicated that the wind speed was an important influencing factor for the variations of precipitation δ¹8O. With the increasing rainfall levels, the intercept and slope of meteoric water line also increased, and this phenomenon suggested that there was a secondary evaporation effect under sub-cloud in stable isotopes of precipitation. The backward trajectory model showed that the main moisture sources during dry season came from the westerly and the inland. However, during wet season, the remote ocean vapor was the main moisture source in Mengzi, and the δ¹8O values in precipitation were much lower during typhoon period.