街尘与城市降雨径流污染的关系综述

街尘是引起城市面源污染分布最为广泛、最重要的污染物载体,街尘及其负载的污染物与降雨冲刷相关过程的全面认识,对有效控制城市地表径流污染有着重要的意义.针对全球快速城市化背景下街尘及其降雨冲刷污染的研究现状,阐明了街尘及其降雨冲刷污染的不足与难点,并对未来研究方向的突破性给予展望.

Research progress on the relationship of pollutants between road-deposited sediments and its washoff

Road-deposited sediment (RDS) on impervious surfaces is an important carrier of contaminants. The road surface is a sink and source of metals and other contaminants in urban environments. During rainfall, RDS is transported to receiving waters, where it has a marked effect on water quality and aquatic biota. Because of rapid global urbanization, urban surface runoff containing contaminated RDS is becoming an increasingly serious environmental problem. Understanding the relationship between the RDS contribution and its washoff process is essential for controlling urban runoff pollution. Most previous studies have investigated contaminants in RDS and runoff separately. But the following aspects remain unclear: 1) The variety of RDS and its associated contaminants along urban-rural gradients. An urban-rural gradient pattern is common in the context of rapid urbanization in China. It strongly affects land use zoning, the proportion of impervious surfaces, traffic density, energy consumption, street cleaning methods and spatial distribution of manufacturing facilities. However, most studies have been conducted in central urban areas of larger cities, and few have investigated RDS variety and associated contaminants along urban-rural gradients. 2) The RDS washoff process from road surfaces. Because of the difficulty of using natural rainfall events to investigate rigorous RDS washoff processes, washoff is the least understood among the three processes (RDS buildup, washoff and transport) preceding material entry into receiving waters. 3) The quantitative relationship of contaminants between RDS and runoff. Previous studies have suggested that RDS and washoff particles have either an exponential, rating curve, or other relationship. The relationship depends on a range of parameters, such as surface characteristics, rainfall intensity and duration, RDS grain sizes, land use, and others. However, it is unclear how grain size composition influences the relationship of pollutants between RDS and washoff particles. This paper represents a breakthrough in the study of these questions in the following aspects: 1) How RDS from an urban-rural gradient affects the relationship of contaminants in washoff particles. The quantity, grain size, and particle mobility of RDS are critical for assessing the role of RDS and its associated contaminants in urban runoff. Indeed, the urban-rural environmental gradient has an important influence on RDS quantity and grain size distribution. 2) The RDS washoff process from the road surface using rainfall simulation. Simulated rainfall has provided greater flexibility and control of fundamental rainfall parameters, such as intensity and duration. Thus, rainfall simulation for different-sized RDS particles in surface runoff can be used to provide insight into how the urban gradient affects the potential washoff load and ratio of pollutants associated with RDS. 3) The RDS grain size distribution is an important factor in determining the mobility of particles and their associated pollutant concentrations. Grain size composition is also a critical factor to establish the relationship between RDS and washoff particles, because surface washoff selectively transports RDS of particular grain sizes. The washoff percentage of each RDS size fraction (F_w) varies with RDS grain size, with smaller grain sizes associated with higher values of F_w. Washoff particles have higher proportions of smaller grain sizes than those in RDS.