Event-based size distributions of particulate matter transported during urban rainfall-runoff events

Journal of Hazardous Materials

Wang

et al. 2010

250

101

a b s t r a c tPollutant washoff from road-deposited sediment (RDS) is an increasing problem associated with the rapid urbanization of China that results in urban non-point source pollution. Here, we analyzed the RDS grain size distribution and its potential impact on heavy metal pollution in urban runoff from impervious surfaces of urban villages, colleges and residences, and main traffic roads in the Haidian District, Beijing, China. RDS with smaller grain size had a higher metal concentration. Specifically, particles with the smallest grain size (<44 m) had the highest metal concentration in most areas (unit: mg/kg): Cd 0.28-1.31, Cr 57.9-154, Cu 68.1-142, Ni 25.8-78.0, Pb 73.1-222 and Zn 264-664. Particles with smaller grain size (<250 m) contributed more than 80% of the total metal loads in RDS washoff, while suspended solids with a grain size <44 m in runoff water accounted for greater than 70% of the metal mass in the total suspended solids (TSS). The heavy metal content in the TSS was 2.21-6.52% of that in the RDS. These findings will facilitate our understanding of the importance of RDS grain size distribution in heavy metal pollution caused by urban storm runoff.

Section: Discussionmentioning

confidence: 99%

“…Most previous studies have focused on the pollutant distribution in different size RDS and the concentration or transport of pollutants in runoff water separately [7,[23][24][25][26]. Few studies have investigated the grain size distribution in RDS and suspended solids in stormwater runoff simultaneously [8,27].…”

Section: Introductionmentioning

confidence: 99%

Grain size distribution of road-deposited sediment and its contribution to heavy metal pollution in urban runoff in Beijing, China

Journal of Hazardous Materials

Wang

et al. 2010

250

101

“…Previous studies indicated that the urbanerural gradient had an important effect on RDS amounts, grain size composition, metal types and concentrations associated with it (Rogge et al, 1993;Kupiainen et al, 2005;Kim and Sansalone, 2008;Thorpe and Harrison, 2008). Zhao et al (2011) reported that metal concentrations decreased and quantities of metals per unit area increased from urban to rural areas along the urbanerural gradient in Beijing.…”

Section: Introductionmentioning

confidence: 96%

Risk assessment of metals in road-deposited sediment along an urban–rural gradient

Environmental Pollution

2013

110

a b s t r a c tWe applied the traditional risk assessment methods originally designed for soils and river sediments to evaluation of risk associated with metals in road-deposited sediment (RDS) along an urbanerural gradient that included central urban (UCA), urban village (UVA), central suburban county (CSA), rural town (RTA), and rural village (RVA) areas in the Beijing metropolitan region. A new indicator RI RDS was developed which integrated the RDS characteristics of mobility, grain size and amount with the potential ecological risk index. The risk associated with metals in RDS in urban areas was generally higher than that in rural areas based on the assessment using traditional methods, but the risk was higher in urban and rural village areas than the areas with higher administration units based on the indicator RI RDS . These findings implied that RDS characteristics variation with the urbanerural gradient must be considered in metal risk assessment and RDS washoff pollution control.

“…Particle size composition is a critical factor in this relationship because surface washoff selectively transports RDS of particular particle sizes [12,13]. The washoff percentage of each RDS size fraction (F w ) varies with the particle size of RDS, with smaller particle sizes being associated with higher values of F w .…”

Section: Discussionmentioning

confidence: 99%

“…Knowledge of total metal concentration is insufficient for assessment of environmental risk [10]. Chemical fractions are critical to the evaluation of potentially toxic metals in RDS and washoff particles [11][12][13]. The amount, particle size and particles mobility of RDS strongly affect their potential contribution to washoff particles.…”

Section: Introductionmentioning

confidence: 99%

Understanding the relationship between heavy metals in road-deposited sediments and washoff particles in urban stormwater using simulated rainfall

Journal of Hazardous Materials

2013

h i g h l i g h t sHeavy metal concentrations in washoff particles increased by 10-30% compared with RDS. Rainfall intensity and duration did not affect increased rate of metal concentrations. Grain size of RDS and washoff particles carrying most heavy metals was different. Metal concentrations in RDS washoff decreased along the urban-rural gradient. Understanding the relationship between heavy metals in road-deposited sediments (RDS) and washoff particles is essential to controlling urban runoff pollution. RDS and its associated heavy metals were investigated along the urban-suburban-rural gradient around Beijing, China. RDS washoff and its associated metal contaminants in different particle size fractions were evaluated using simulated rainfall. The results showed that the washoff percentage of RDS decreased along the urban-rural gradient. The Cu, Zn, Ni, Cr and Pb contents in washoff particles were 28.1%, 20.0%, 19.7%, 11.6%, and 11.4% higher than those in RDS, respectively. Additionally, different metals showed increases in different chemical fractions. RDS particles <105 m accounted for 40% of the total mass in RDS, but 50%, 70% and 75% of the total metal content in RDS, washoff particle mass and washoff particle metal content, respectively. Rainfall intensity and duration affected the amount of metals in washoff, but did not lead to an increase in the percentage of metals with different chemical fractions in washoff particles. The findings presented herein will facilitate development of strategies for control of urban diffuse pollution from RDS.