东江上游高风险支流不同功能区初期雨水径流污染特征分析

Analysis on Pollution Characteristics of Initial Rainwater Runoff from Different Functional Areas of High Risk Tributary in Dongjiang Upriver

了解不同外界条件下初期雨水径流污染物的变化是有效控制面源污染的重要基础。根据径流曲线法(SCS)对东江上游高风险支流区中农田区、交通道路区、住宅商业区和工业区4个不同功能区的初期雨水径流进行采样,按照国家标准水质分析方法进行监测,并对不同功能区初期雨水径流水质的变化规律及主要污染物的相关性进行分析。研究结果表明,降雨前期晴天数、降雨量、降雨强度对初期雨水径流水质变化均有明显影响。当前期晴天数多、雨量大且降雨强度大时,污染物质量浓度峰值出现的时间早、质量浓度下降趋势明显。随着降雨历时的延长,初期雨水径流主要污染物SS、COD_(Cr)、TN、TP及NH_3-N的质量浓度大都呈现下降趋势,且污染物质量浓度峰值大部分出现在前5 min。其中,SS质量浓度以农田区最高,相对于其他功能区,污染物质量浓度最高可达14倍之多。COD_(Cr)、TN、TP及NH_3-N质量浓度均以住宅商业区最高,最高分别可达1 136、17.56、3.96、25.36 mg·L^(-1),相对于其他功能区而言,住宅商业区更易导致水质污染。从最典型降雨事件分析来看,只有交通道路区的COD_(Cr)、TP、TN与SS之间呈现正相关,其相关系数分别为0.775、0.798、0.826,其余3个功能区域的主要污染物之间则出现负相关,表明初期雨水具有复杂性,受多重外界因素影响。该研究结果对入江污染物负荷量控制及东江水环境保护具有一定的意义。

The effective reduction of the non-point source pollution is greatly based on the analysis of the types of main pollutants ininitial rainwater runoff and their main influences on water quality, and on the knowledge of the changes of pollutants under thedifferent conditions. In this study, the initial rainwater runoff of four different functional areas like farmland, traffic area, residentialbusiness area and industry area in the high-risk tributary area of Dongjiang River was sampled with SCS-CN method, the sampleswere monitored according to the national standard water quality analysis method, and the changes of water quality of the initialrainwater runoff and the correlation of the main pollutants in the four different functional areas were analyzed. The results showedthat significant impacts on the quality of initial rainwater runoff were played by the number of sunny days before rainfall, the amountof rainfall, the intensity of rainfall. Under the condition of high appearance rate of sunny days before rainfall, and heavy rain of highintensity or long duration, the peak value of quality density of the pollutants appeared earlier and the quality concentration decreasedsignificantly. With the extension of rainfall duration, the mass concentration of SS, CODCr, TN, TP and NH3-N in the initial rainwaterrunoff showed a decreasing trend, and the concentration peak value of the pollutants mostly appeared in the first 5 min. Among themain pollutants, the highest mass concentration of SS was obtained in the farmland area, compared with other functional areas, massconcentration up to 14 times as much. The mass concentration of TN, TP and NH3-N were highest in residential business area, themass concentrations of pollutants were up to 1 136, 17.56, 3.96, 25.36 mg.L-1. Compared with other areas, the residential businessneeded more attention, because the area was more susceptible to water pollution. What found in the analysis of the most typicalrainfall events was as follows： the positive correlation between CODCr, TP, TN and SS only appeared in the traffic area, of which thecorrelation coefficients were 0.775, 0.789, 0.826, respectively, and the main pollutants in the other three functional areas had anegative correlation with CODCr, TP, TN and SS, it showed that the initial rainwater was complex and influenced by multipleexternal factors. All the above analysis conclusion in this paper are of vital importance to reduce total pollutant load into theDongjiang River, which is responsible for the work of protecting the water quality.