| Now, China is in the high speed process of urbanization. But at the same time, the efficient and convenient city life is accompanied by a variety of serious environmental problems. The pollution of road rainfall runoff in urban area is one of these problems and its harmfulness is becoming more and more obvious. Studying the pollution characteristics and the controlling measures is of great importance to control the non-point pollution and to improve the water ecological environment of Suzhou.In this paper, a typical mixed residential and commercial area and educational area in Suzhou were taken as the research object. Water samples of different rainfall events were collected from these two functional districts. Through experimental analysis and data processing, we have preliminarily mastered the water quality characteristics of the road runoff in this region and knew its influence on the surrounding water. The main results of this paper are shown as followed:(l)The runoff pollution in these two regions are all serious. In addition to TP of the educational area and Cu of both of the two functional districts, the highest value of all the other pollution indicators are all not meet the grade v of the surface water quality standard. However, the distributions of pollutants in different functional areas also have their own differences. The mixed commercial and residential area is very busy and its ground situation is complex. So, its road runoff pollution is significantly higher than the educational area.(2) In a complete rainfall event, although all kinds of the contaminants will changes along with the rainfall process, on the whole, we can still get a certain rule. The general trend is that the rainfall runoff is more seriously polluted at the initial stage of rainfall and the runoff of the initial stage may contain60%-90%pollutants. As the rain continued, the indexes will decline and finally stabilized.(3) By analyzing the first flush effect of the rainfall runoff we can find that most of the pollutants will show the FFE. But different rainfall events affect the first flush to a different degree. Rainfall intensity is the most import influence factor of the FFE. Usually, the greater the rainfall intensity, the more obvious the FFE is. Different pollutants have the different degree of the FFE. In this paper, the FFE of COD and NH3-N is the most obvious.(4)There is a certain correlation relation between the different rainfall pollution indicators. The relationships between COD and SS and TP and SS are the most obvious while the relationship between NH3-N and SS is not significant. Three heavy metals have some correlation relation with SS and the order of the relation is Pb> Cr> Cu. So, we can predict the contents of other pollutants through SS.(5) The influence factors of runoff quality is complex. For example the rainfall intensity, the situation of runoff surface, the road traffic condition and the sunny day length will all have great influence on the road rainfall runoff quality. All these factors act on the runoff at the same time and this will make the problem more complicated.(6) Combined with the data from experiment and an appropriate model, we can estimate the discharge load rate of the pollutants in different functional areas of Suzhou. The results indicate that, the discharge load rate in education areas is far lower than the mixed commercial and residential area.(7) Finally, based on the mature overseas management experience and combined with the characteristics of Suzhou local places and the experimental results, the article puts forward a series of measures to deal with the road rainfall runoff pollution in Suzhou urban area including the non-engineering measures which control the pollutions from the source and the engineering measures which control the pollutions in the rainfall process and the final stage. |
PDF Full Text Request