广州番禺区不同地类的非点源污染排放特征

Characteristics of Non-point Source Pollution Discharge under Different Land Use Conditions in Panyu District of Guangzhou

在广州番禺区建设代表城市、农田、村镇、园地4类典型集水区的径流试验小区,对每个径流小区采集3场有效降雨径流以研究不同土地利用类型的非点源污染负荷输出特征。结果表明,不同土地利用类型的污染物输出浓度差别较大,TSS和COD输出浓度(EMC值)的大小排列顺序为园地>农田>村镇>城市;NH3--N为农田>城市>园地>村镇;NO3--N为城市>农田>村镇>园地;TN为农田>城市>园地>村镇;TP为农田>园地>城市>村镇。对于农田集水区,TSS和COD的输出明显受降雨的影响,而N、P污染物的输出受施肥的影响更为显著;对于城市集水区,晴天累积污染物的数量和降雨情况是决定初期径流中污染负荷的主要因素。污染负荷与径流量之间相关性显著,且颗粒物是携带污染物的重要载体。各径流小区的初始冲刷效应分析结果显示,不透水地面更易发生降雨初期冲刷;降雨强度是影响降雨径流初始冲刷的关键因素。

Four typical runoff plots were constructed in Panyu District of Guangzhou, representing urban,cropland,rural and orchard catchment respectively. Three rainfall events per runoff plot were monitored to investigate characteristics of non-point source pollution discharge under different land use conditions.The results show that the pollutant concentration varies for different land use conditons. For TSS and COD,the sequence of event mean concentration is as for TSS and COD; cropland〉urban〉 orchard〉rural for NO3--N and TN;urban〉cropland〉rural 〉orchard for NO3--N;cropland〉 for TP. For cropland catchment, fertilizer exerts obvious influence on discharge concentration of pollutant such as N and P,but not TSS and COD,which is greatly influenced by rainfall.For urban catchment,pollution load in preliminary runoff depends on rainfall and the amount of pollutant accumulated during dry days. Regression analysis between pollution load and runoff in four catchments result in a high value of pearson correlation coefficients,and particles are an important carrier of pollutants. The analysis of first flush effect demonstrates that first flush effect is occurred more frequently in impervious surfaces than in other catchments and the influence of rainfall intensity on the first flush is significant.