Toxicity Evaluation of Different Exposure Scenarios of Road Dust Using Daphnia magna and Artemia salina as Aquatic Organisms, and Prosopis cineraria and Vachellia tortilis as Native Plant Species

Particulate matter (PM10) deposited as road dust is considered an important source of contamination from atmosphere. However, there are limited studies on the toxicity of road dust as such on different organisms. This study evaluates the toxicity of road dust using different extraction scenarios on Daphnia magna and Artemia salina as aquatic organisms and also on Prosopis cineraria and Vachellia tortilis as local plant species. Chemical analysis of different extracts shows considerable amount of trace metals, however the trace metals in the dust extract associated with suspended sediment were not absorbed by the receptors. On the other hand, the concentration of trace metals in the artificial mixture was found bioavailable and absorbed causing a high percentage of mortality. In the plant assay, significant difference was obtained in the germination percentage between the control and three different extraction exposures in both plant species. The mean root length of P. cineraria and V. tortilis were higher in 20% and 50% extracts than the control probably due to the availability of nutrients from the dust extract. Interestingly however, the seedling vigor index was the opposite with higher index in the control and lower in dust extracts that contain heavy metals.

Research Progress and Prospect of Road Dust Suppressants

Road dust has great adverse effects on traffic quality,traffic safety,atmospheric environment quality,and human health.Therefore,with the continuous development of modern science and technology,the research of road dust suppressants is also progressing.To promote the rational application and development of road dust suppressants,the research progress and prospects of them are analyzed in this paper.It includes a basic overview of road dust suppressants,the main types,the usage and precautions,and the main development direction.It is hoped that this analysis can provide some reference for further research and development of road dust suppressants.

Source identification, contamination status and health risk assessment of heavy metals from road dusts in Dhaka, Bangladesh

In this study, concentrations of Cr, Mn, Ni, Cu, Zn, Cd and Pb were determined in road dusts collected from different locations in Dhaka to assess source, contamination status and health risk. Energy-dispersive X-ray fluorescence spectroscopy and energy-dispersive X-ray spectroscopy were used to determine Cr, Mn, Ni, Cu, Zn, Cd and Pb and their mean concentrations were 162.27 ± 29.46, 721.18 ± 180.14, 35.65 ± 12.55, 104.56 ± 128.33, 515.32 ± 321.90,BDL, and 342.82 ± 591.20 mg/kg, respectively. Among the heavy metals, highest concentrations of Cu, Zn and Pb were found at urban sites-7(municipal waste dumping) and 8(medical waste incineration). Highest concentration of Cr followed by Cu and Zn was found at site-5(Tejgaon, urban). Principal component analysis revealed that anthropogenic activities are the potential sources for Cr, Ni, Cu, Zn and Pb while earth crust for Mn. Pollution index and pollution load index results suggested that all the sites were contaminated and/or degraded by Cr, Cu, Zn and Pb except sites-9(urban), 10(sub-urban), 11(rural) while sites-7 and 8(urban) were extremely degraded. For noncarcinogenic health risk, hazard quotient values for dermal were higher compared to that of inhalation/ingestion. Though hazard index values were less than 1 at all the sites, these were at least one order of magnitude higher for children group than that of adult group, thus the children group may face more noncarcinogenic health risk at sites -7 and 8. Values of incremental lifetime cancer risk were from 10to 10showed no carcinogenic health risk by road dusts contaminated with the heavy metals.

Distribution of platinum group elements in road dust in the Beijing metropolitan area, China

Dust samples collected from the Beijing metropolitan area （China） were evaluated to determine the distribution and the concentration of platinum group elements （PGEs）. The dust particles that were smaller than 100 mesh size fraction （150 μm） were analyzed after aqua regia digestion. Concentrations ofPt, Rh, and Pd were found to be between 3.96 and 356.3 ng/g, 2.76 and 97.11 ng/g, and 0.1 and 124.9 ng/g, respectively, in the urban areas of Beijing, whereas for the background samples collected from the suburbs of Beijing, the concentrations of Pt, Pd, and Rh were very low and ranged from 0.1 to 0.9 ng/g, 0.5 to 1.4 ng/g, and 0.8 to 2.2 rig/g, respectively. The distributions of PGEs in road dust were an accurate reflection of the levels of pollution and were found to match with the local traffic conditions. A strong positive correlation was established among all the dements found in road dust. This suggests that emissions of abraded fragments from vehicle exhausts may be the source of the high concentration of Pt, Rh, and Pd in road dust along the main roads of Beijing.

Development and characterization of formulation of dust-suppressant used for stope road in open-pit mines

The components of dust-suppressant were determined based on the analysis on characteristics and mechanisms of road dust raising in open-pit mines. The components were initially selected from moisture agent, coagulation agent and surfactant. The optimal formulation was determined based on orthogonal test and using the water loss rate as the evaluation index. The performances of moisture releasing and adsorption, wind resistance of optimal formulation in the natural environment were tested. The results show that the formula obtained in experiments provide a good performance of moisture absorption and water retention, and it also had a good dust preventing and controlling performance due to its high surface strength and consolidation under dry conditions. It has good application prospects considering the wide variety of sources for materials and the simple preparation process.

Assessment of Road Dust Contamination in India

The road dusts (RD) are fugitive in nature causing potential health hazards to people living in highways. They are generated from different sources on the roads and being a valuable archive of environmental information. In the present work, contamination assessment of 18 heavy metals and ions in road dusts of the country are described. Techniques i.e. ion selective, ion chromatography and atomic absorption spectrophotometers were used for analysis of the ions and metals. The content of F-, Cl-, , , , Na+, K+, Mg2+, Ca2+, As, Cr, Mn, Fe, Ni, Cu, Zn, Pb and Hg in the road dusts was ranged from 75 - 895, 276 - 12718, 48 - 1423, 243 - 10,580, 11 - 539, 290 - 46,484, 110 - 7716, 84 - 1771, 595 - 15,955, 24 - 42, 164 - 526, 1711 - 5218, 63,850 - 144,835, 47 - 62, 81 - 720, 166 - 450, 92 - 295 and 0.05 - 0.12 mg/kg with mean value of 224 ± 43, 3734 ± 895, 592 ± 895, 2859 ± 662, 143 ± 29, 4826 ± 2049, 1565 ± 411, 837 ± 121, 8545 ± 1288, 31 ± 4, 246 ± 82, 3002 ± 851, 91,331 ± 18,587, 54 ± 4, 206 ± 145, 241 ± 64, 171 ± 42 and 0.08 ± 0.02 mg/kg, respectively (at 95% probability). The enrichment, variation, correlation and sources of the contaminants are discussed.

Estimating emissions and concentrations of road dust aerosol over China using the GEOS-Chem model

Paved road dust is one of the most important aerosols in China. The authors estimated road dust emissions using an empirical model （AP-42 model） developed by the U.S. Environmental Protection Agency, and simulated road dust concentrations over China for the years 2006-2011 using the GEOS-Chem model.The annual road dust emissions amount averaged over 2006-2011 is estimated to be 2331.4 kt, with much higher emissions in eastern China than in western China. Because of heavy traffic and a dense road network, emissions are high over Beijing-Tianjin-Tanggu （BTT）, Henan Province, and Shandong Province. Meanwhile, emissions are calculated to be 459.1, 112.0, and 102.7 kt, respectively, over BTT, the Pearl River Delta （PRD） region, and the Yangtze River Delta （YRD）. Due to the monthly variation of precipitation, road dust emissions over China are simulated to be highest in December and lowest in June. The highest annual mean road dust concentration is simulated to be 14.5 tJg m-3 in Beijing. Over 2006-2011, because of the increases in road length and number of vehicles, annual road dust emissions for China as a whole, Bl-r, the PRD, and the YRD, are simulated to increase by 260%, 239%, 266%, and 59%, respectively, leading to 233%, 243%, 273%, and 100% increases in road dust concentrations in these regions, respectively. Our results have important implications for air pollution control in China.

Influence of Traffic Volume on Fugitive Road Dust Emissions in Beijing, China

Eighty sites were set up to monitor road dust fall and 80 locations were selected to sample silt loading in April, August, and November 2007 and January 2008 in the Beijing metropolitan area. Fugitive road dust emission strengths were calculated using the AP-42 emission factor model. Silt loading on Beijing urban roads was typically less than 1.0 g/m^2, the PM10 emission strength was typically less than 100 kg/km·day, and road dust fall was typically less than 40 t/km^2·30day. The relationships between traffic volume, silt loading, fugitive road dust emission strength and road dust fall were studied in the Beijing metropolitan area. The results indicate that silt loading and emission factors are negatively correlated with traffic volume, but the PM10 emission rate and road dust-fall are positively correlated with traffic volume.

Analysis on emission factor of fugitive dust from road traffic

ＡｎａｌｙｓｉｓｏｎｅｍｉｓｉｏｎｆａｃｔｏｒｏｆｆｕｇｉｔｉｖｅｄｕｓｔｆｒｏｍｒｏａｄｔｒａｆｉｃＦｕＬｉｘｉｎＤｅｐａｒｔｍｅｎｔｏｆＥｎｖｉｒｏｎｍｅｎｔａｌＥｎｇｉｎｅｅｒｉｎｇ，ＴｓｉｎｇｈｕａＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１０００...

Estimation of road dust using BSNEs

Mining is a core industry in Sweden and plays an important role in the economic development throughout the country. Though the importance of mining dust has been well recognized, the quantification of dust production with regard to individual source activity has rarely been done in Sweden. Depending on the type of source activity, dust estimation method can be chosen from three alternatives: exposure profiling methods, back calculation method, and wind erosion prediction method. Also included in the paper is an example of experiment, which was executed on two unpaved roads in Lulea, Sweden by using exposure profiling method. The experiment concluded that dust emission due to vehicle transportation is strongly dependent on traveling speed and road bed material.

Heavy metal contamination and health risk assessment of road dust from landfills in Dhaka-Narayanganj, Bangladesh

In the recent years,air pollution has become an alarming issue for human health in many rapidly growing megacities including Dhaka and Narayanganj.Herein,pollution status and health risk have been assessed by the road dusts collected from landfills in Dhaka and Narayanganj through determination of heavy metals including Pb,Cd,Cr,As,Cu,Ni,Zn and Mn using atomic absorption spectroscopy.The collected dust samples have been grouped into three sizes,for example,<300−>150,<150−>75 and<75μm,to assess the degree of heavy metal accumulation in the dust particles.The dust particles were accumulated with high concentrations of Pb and As at Matuail landfills,whereas Cd,Cr,Zn,and Mn concentrations were highest at Narayanganj landfills.The finer particles,for example 75μm,accumulated substantial concentrations of heavy metals.Pollution index and pollution load index(PLI)results revealed that all of the sites were deteriorated by Pb,Cd,Cu,Zn and Ni.PLI results exhibited that the quality of the Matuail landfill area was severely deteriorated.In terms of non-carcinogenic health risk,the values of hazard quotient for ingestion were greater than those for inhalation and dermal pathways.For adult groups,hazard index values for the Matuail landfills and medical waste incineration sites were greater than 1,while for the children groups,the values for the same areas,including the Narayanganj landfills,were also larger than 1.These values were at least one order of magnitude higher for the children groups than for the adult groups.Given the results,it would be reasonable to draw the conclusion that non-carcinogenic health risks for children may be more prevalent in the relevant areas.

Tracking of microplastics distribution patterns and their characterisation in deposited road dust from Dhaka city,Bangladesh

The widespread presence of microplastics(MPs)in road dust has considerable concern regarding their potential risks to ecosystems and human health.Despite the massive production of plastic,the erudition of MPs distribution patterns in various sizes of deposited road dust is still limited around the globe.Thus,the aim of this research is to provide an unambiguous picture of MPs distributional pattern,identification,classification,quantification,and features from road dust in various zones and types of roadways in Dhaka,Bangladesh.This study examined MPs in road dust samples with particle sizes ranging from 300 to 150 mm(Group-A),149-75 mm(Group-B),and<75 mm(Group-C).This work extracted MPs from road dust using 30%H_(2)O_(2),1.6 g/cm^(3)ZnCl_(2),and 0.45 mm filter paper.A fluorescent microscope(Motic B410E,Germany),Motic Pictures,and 3.0 ML software were utilized to identify MPs visually.Additionally,FTIR and SEM were utilized to determine the chemical composition of MPs.Group-A Road dust samples had a significantly higher concentration of MPs(38945 items/kg)compared to Group-B and<75 mm Group-C dust(16720 and 5945 items/kg,respectively).The distribution hierarchy for total MPs on average by location and type of road is as follows:paved road(355 items/5 g)>unpaved road(325 items/5 g)>soil samples(294 items/5 g),roadside dust samples(284 items/5 g),and mid-road(283 items/5 g).By taking into account all sizes of road dust samples,the MPs were classified as fiber(70.26%),fragment(26.12%),beads(0.66%),films(1.32%),and foams(1.58%).It was found that adults inhaled MPs an average of 1612 items/day,while they ingested an average of 880 items/day.Children had an inhalation rate of 1232 items/day and an ingestion rate of 10267 items/day,which was 4e17 times greater than in other countries.This study identified 22 MPs polymer types,and SEM results show that MPs surfaces are being weathered into nanoplastics,creating a more hazardous environment.

Volcanic emissions and atmospheric pollution:A study of nanoparticles

The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes.Although many cities are close to active volcanoes,few studies have evaluated their influence in road dust composition.Air quality in urban areas is significantly affected by nonexhaust emissions(e.g.road dust,brake wear,tire wear),however,natural sources such as volcanoes also impact the chemical composition of the particles.In this study,elements from volcanic emissions such as Si>Al>Fe>Ca>K>Mg,and Si-Al with K were identified as complex hydrates.Similarly,As,Hg,Cd,Pb,As,H,Cd,Pb,V,and salammoniac were observed in nanoparticles and ultrafine material.Mineral composition was detected in the order of quartz>mullite>calcite>kaolinite>illite>goethite>magnetite>zircon>monazite,in addition to salammoniac,a tracer of volcanic sources.The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health.The road dust load(RD_(10))ranged between 0.8 and 26.8 mg m^(−2)in the city.

Effectiveness evaluation of water-sprinkling in controlling urban fugitive road dust based on TRAKER method: A case study in Baoding, China

Fugitive road dust(FRD)contributes a great deal to urban rainwater and air pollution and is commonly controlled by water-sprinkling in most Chinese cities.However,there is a lack of information on its effectiveness.We used the Testing Re-entrained Aerosol Kinetic Emissions from Roads(TRAKER)method to monitor different types of roads in Baoding city before and within 1 hr after water-sprinkling and obtained the road dirtiness index(a)and PM concentration in the road environment(T^(∗)_(T)),to evaluate the removal efficiency for PM deposited on the road surface(ηa)and the reduction efficiency for the PM concentration in the road environment(ηPM).The results give that theηa for three types of roads is ranked:branch road(87%-–100%)>major arterial road(80%-83%)>minor arterial road(68%-77%),and the ηPM ranked:minor arterial road(70%)>branch road(46%-58%)>major arterial road(37%-53%).Theηa andηPM varied non-linearly with time and presented a quadratic curve.The average effective control time(ηa>0)was 62min on themajor andminor arterial roads,and much longer than 1 hr on branch roads.The ηPM values diminished completely by 72 min on average from the end of sprinkling for the three types of roads.Water-sprinkling can remove PM10 particles from the road surface and reduce their concentration in the road environment more thoroughly than PM2.5.Our findings could be helpful for controlling urban FRD emissions more efficiently and precisely.

Contamination and health risk assessment of heavy metals in road dust in Bayan Obo Mining Region in Inner Mongolia, North China

The objective of this study was to investigate the concentration and spatial distribu- tion patterns of 9 potentially toxic heavy metal elements （As, Cd, Co, Cr, Pb, Cu, Z.n, Mn, and Ni） in road dust in the Bayan Obo Mining Region in Inner Mongolia, China. Contamination levels were evaluated using the geoaccumulation index and the enrichment factor. Human health risks for each heavy metal element were assessed using a human exposure model. Results showed that the dust contained significantly elevated heavy metal elements concen- trations compared with the background soil. The spatial distribution pattern of all tested met- als except for As coincided with the locations of industrial areas while the spatial distribution of As was associated with domestic sources. The contamination evaluation indicated that Cd, Pb, and Mn in road dust mainly originated from anthropogenic sources with a rating of ＂heav- ily polluted＂ to ＂extremely polluted,＂ whereas the remaining metals originated from both natural and anthropogenic sources with a level of ＂moderately polluted＂. The non-cancer health risk assessment showed that ingestion was the primary exposure route for all metals in the road dust and that Mn, Cr, Pb, and As were the main contributors to non-cancer risks in both children and adults. Higher HI values were calculated for children （H1=1.89）, indicating that children will likely experience higher health risks compared with adults （H1=0.23）. The cancer risk assessment showed that Cr was the main contributor, with cancer risks which were 2-3 orders of magnitude higher than those for other metals. Taken in concert, the non-cancer risks posed by all studied heavy metal elements and the cancer risks posed by As Co, Cr, Cd, and Ni to both children and adults in Bayan Obo Mining Region fell within the acceptable range.

RESUSPENSION METHOD FOR ROAD SURFACE DUST COLLECTION AND AERODYNAMIC SIZE DISTRIBUTION CHARACTERIZATION

Traffic-generated fugitive dust is a source of urban atmospheric particulate pollution in Beijing. This paper introduces the resuspension method, recommended by the US EPA in AP-42 documents, for collecting Beijing road-surface dust. Analysis shows a single-peak distribution in the number size distribution and a double-peak mode for mass size distribution of the road surface dust. The median diameter of the mass concentration distribution of the road dust on a high-grade road was higher than that on a low-grade road. The ratio of PM2.5 to PM10 was consistent with that obtained in a similar study for Hong Kong. For the two selected road samples, the average relative deviation of the size distribution was 10.9% and 11.9%. All results indicate that the method introduced in this paper can effectively determine the size distribution of fugitive dust from traffic.

Application of micro-morphology in the physical characterization of urban road dust

Urban road dust was collected from Vellore City,Tamil Nadu,India,and analyzed.Scanning electron microscopy(SEM)was used to examine road dust from nine sampling locations in the study region.SEM image analysis was used to identify various shape factors of collected dust particles.The equivalent spherical diameter of most particles was between 10μm and 30μm.Fine particles had greater concentrations at locations with higher traffic flow.Particles were categorized into four classes based on their shape factors,viz.,spherical,mineral,elongated,or irregular.Spherical particles had the smallest mean equivalent diameter(1.95μm)and mineral particles had the largest diameter(33.3μm).Spherical particles made up the smallest portion of road dust(0-12%)in the study region and mineral particles made up the largest(45-65%).Elongated and irregular particles,each made up 23-30%of road dust.Electron dispersive X-ray spectroscopy analysis was used to identify the elemental composition of dust particles.Spherical particles were mostly from combustion sources and mineral particles were largely of crustal origin.No individual source was found for irregular and elongated particles.Biological debris was the major source of irregular particles.