Study on pollutants characteristics of non-point source pollution on urban campus area and statistical method for determining the first flush time

摘要

For urban non-point source pollution, different kinds of subarea have different pollution characteristics. We take an urban campus as our study subarea. The research work includes underlying surface dividing and sampling point selecting, sampling apparatus designing and installation, runoff pollutants examination, results analysis. The author obstained 423 samples from 9 different underlying surfaces and 1 natural rainfall during rainwater runoff process during recent 3 years. The monitoring water quality constituents are water temperature, PH value, dissolved oxygen, electrical conductivity, turbidity, suspended solids, alkalinity, ammonia nitrogen, total nitrogen, total phosphorus, total organic carbon, chemical oxygen demand, total hardness, Ca2+, Mg2+, sulfate, heavy metal, and so on. The program has obtained more than 5000 chemical test data. The research result indicates that: the main pollutants in the campus are COD, suspended solids and TN.while the concentrations of heavy metals and inorganic substances are relatively very low, according to the rainwater quality monitoring data collected in Beijing University of Technology and Xidawang Road by our research team in recent years. Furthermore we provided a statistical method for determining the first flush time. For the roof underlying surface in the research campus, the first flush time is 10 minutes.