雨水花园施工过程的场地污染特征研究

Site Pollution Characteristics during Construction of Rain Garden

当前我国海绵城市建设中低影响开发(LID)施工场地污染普遍存在,但却没有引起足够的重视与正确的认识。为此,以镇江市雨水花园施工场地为例,分析了不同施工阶段地表沉积物的静态空间分布特征与动态径流污染特征,并与未施工场地进行对比。结果表明,开挖、铺砂、填土及种植阶段的地表沉积物单位面积质量分别为(478.7±14.57)、(261.74±37.79)、(76.18±17.22)、(31.83±9.44)g/m^2,均高于未施工场地[(17.71±2.81)g/m^2],且各施工阶段的地表沉积物均以粗粒径(149~1 000μm)为主;各施工阶段地表沉积物中的重金属含量均低于未施工场地,但重金属污染负荷均高于未施工场地,由高到低依次为开挖阶段、铺砂阶段、填土阶段、种植阶段;地表沉积物的扩散迁移距离约为120 m。施工道路径流中总悬浮固体与重金属浓度均高于未施工道路,施工道路径流中总悬浮固体的场次降雨径流平均浓度(EMC)约为未施工道路的2.8倍。基于上述结果,提出了适合我国海绵城市建设的LID场地径流污染控制措施。

Currently, the low impact development （LID） construction site pollution during sponge cities construction in China is widespread, but it does not arouse enough attention and correct understanding. So, taking rain garden construction in Zhenjiang as an example, static spatial distribution characteristics and dynamic runoff pollution characteristics of road-deposited sediment （RDS） during different construction stages were analyzed and compared with the sites without construction. The results showed that the RDS mass per unit area during excavation, gravel filling, soil filling and planting stage were （478.7±14.57） g/m2, （261.74±37.79） g/m2, （76. 18 ±17.22） g/m2, and （31.83 ±9.44） g/m2, respectively, which were all higher than the sites without LID construction [ （17.71 ±2.81 ） g/m2] , and RDS at each construction stage was dominated by coarse particle size （ 149 - 1 000 μm）. The heavy metals contents of RDS in construction sites were significantly lower than that of the sites without construction, but the heavy metal pollution load was higher than that of the sites without construction, and the order from high to low was excavation stage 〉 gravel filling stage 〉 soil filling stage 〉 planting stage. With the increase distances from the construction site, the mass of RDS per unit area gradually reduced. The diffusion and migration distance of RDS around the construction site was approximately 120 m. The total suspended solid and heavy metal concentration of the construction road runoff were higher than that of the road without construction, and the event mean concentration （EMC） of total suspended solids of the con- struction road was about 2.8 times of that of the road without construction. According to the analysis results, the pollution control measures of LID site runoff in sponge city construction in China were put forward.