Size dependent elemental composition of road-associated particles

Abstract

Stormwater particles often provide transport for metals and other contaminants, however only larger particles are effectively removed by typical best management practices. Fine particles and their associated constituents are more likely to reach receiving waters; this merits further investigation regarding the metal contribution of fine (d p <10 μm) and very fine (d p <1.5 μm) particles. Road associated particles were collected by vacuuming a road surface and by collecting highway stormwater runoff. A cell sorter was employed to sort road associated particles into four size ranges: 0.1-0.3, 0.3-0.5, 0.5-1.0, and 1.0-1.5 μm. These very fine particles, along with six particle size ranges (total range <2-63 μm) separated using a settling column, were analyzed for Al, Mn, Fe, Cr, Ni, Cu, Zn, and Pb using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Enrichment factors (EFs), calculated using Al as a basis to represent crustal contributions, were similar for the vacuumed road dust and the stormwater runoff. Fe and Mn were minimally depleted (0.1x) or near Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. unity for all size ranges (Fe EF range 0.01-3.7; Mn EF range 0.02-10.6). Cr, Ni, Cu, Zn, and Pb were moderately (10x) to considerably (>100x) enriched for most size ranges; these metals were most enriched in the very fine fractions (max EF~4900 in Zn, 0.1-0.3 μm). Based on this preliminary study, a cell sorter is an acceptable means of fractionating aqueous particles of diameter 0.1-1.5 μm. In spite of their minimal relative mass contribution, the very fine particles are environmentally relevant due to their mobility and enrichment in potentially toxic metals.. NIH Public Access

Spatial distribution and human health risk assessment of mercury in street dust resulting from various land-use in Ahvaz, Iran

“…About 500 g of a composite street dust sample was collected by brushing an area of 1×1 m 2 from the pavements. The samples were sieved through a 220 mesh (63µm), air-dried and stored in polyethylene bags and labelled based on Tanner et al (2008) and McKenzie et al (2008). Five grammes of dust collected from the street dust samples were mixed in highly purified nitric-hydrofluoric perchloric acids (5mL HNO3-4mL HCL-2HClO4) (Merck Ltd) to dissolve the street dust samples for measurement of Hg, based on the protocol GB/T 17441-1997and GB/T 17238-1997(Griepink and Tölg 1989.…”

The sources, impact and management of car park runoff pollution: A review

“…Both the pollutant load and size distribution of particulates influences their behaviour and subsequent environmental impact with physicochemical mechanisms such as dissolution, entrainment and settling rates raising particular concerns for the finer fractions of particulate matter (McKenzie et al, 2008;Thorpe and Harrison, 2008;Wei and Morison, 1994). Various researchers have defined the fine fraction of surface sediments using different cut-off points, but typically the descriptor 'fine fraction' relates to the <63 µm, <75 µm or <150 µm fractions.…”

“…Although many of the pollutants identified in Table 3 may be present as either the dissolved or particulate phases, it is widely reported that the majority of the urban pollutant load is associated with particles which act as mobile substrates (Bjorkland, 2011;Herngren et al, 2006;Lee et al, 1997;McKenzie et al, 2008;Chiew 2002, 2004). The finer particles are more readily mobilised during rainfall as evidenced by reported particle size distributions for urban surface runoff (Table 4).…”

“…The increased surface area associated with finer particles, combined with a higher cation exchange capacity, provides them with a greater affinity for pollutants, such as metals (Dong and Lee, 2009;Liebens, 2001;Ujevic et al, 2000). Hence, the finer fractions contribute more pollutants per unit mass and following wash-off will remain in suspension longer providing the opportunity to travel further (Herngren et al, 2006;McKenzie et al, 2008). Knowledge of the particle size distribution of the pollutant load and the environmental behaviour of associated size fractions influences the preferential removal mechanism and hence the selection of surface runoff pollutant mitigation measures.…”

Total concentrations and fractionation of heavy metals in road-deposited sediments collected from different land use zones in a large city (Nanjing), China

“…For example, heavy metals and metalloids in RDSs may be transferred to humans via ingestion, skin contact, or breathing, especially to children due to their ''hand to mouth'' activity during outdoor activities. Therefore, many studies on RDSs have focused on trace metal concentrations, distribution and source identification, particularly in the last decade (Li et al, 2001;Ordóñez et al, 2003;Ahmed and Ishiga, 2004;Azimi et al, 2005;Yongming et al, 2006;McKenzie et al, 2008;Lu et al, 2009). It is well documented that not only the total metal concentrations, but also the chemical forms and phase associations are essential for assessing environmental quality and risk to human health in urban areas.…”