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...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.展开更多
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 informatio...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<sup>-</sup>, Cl<sup>-</sup>, , , , Na<sup>+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, Ca<sup>2+</sup>, 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.展开更多
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 ...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.展开更多
This study analyzed the concentrations and chemical forms of Zn,Cu,Pb,Sb,Cd and Mn in airborne particles,road dusts and soils collected along three expressways in Jiangxi Province,China,with different traffic densitie...This study analyzed the concentrations and chemical forms of Zn,Cu,Pb,Sb,Cd and Mn in airborne particles,road dusts and soils collected along three expressways in Jiangxi Province,China,with different traffic densities,and identified the levels and sources of heavy metal contamination.The concentrations of Zn,Cu,Pb,Sb,and Cd except Mn in airborne particles,road dusts and soils were all in direct proportion to traffic volume.Cd concentrations were low compared with other metals.For instance,the concentrations of Zn,Cu,Pb,Sb,Mn and Cd were 6.6,0.7,2.2,0.1,0.1 and 0.1μg·m-3in PM10along the Changjiu Expressway,792.8,241.4,248.3,9.6,340.5and 8.0 mg·kg-1in road dusts,and 201.1,143.2,59.5,9.5,338.9 and 2.3 mg·kg-1in soils,respectively,but in the case of the ratio of concentration to the environmental background value,most serious contamination was caused by Cd.The sources of the heavy metals were judged by comparisons of the chemical forms of the heavy metals in different environmental media.Pb and Mn in airborne particles were both derived from traffic;Pb in road dusts and soils resulted mainly from the use of leaded gasoline in the past;and Mn in road dusts and soils was derived from parent rocks.Zn,Cu,Sb and Cd in airborne particles,road dusts and soils were derived primarily from traffic,and differences in chemical forms of the heavy metals in different media were due to the interaction between heavy metals in airborne particles and organic matter and other surfaces in road dusts and soils.We also discussed the change of chemical forms of heavy metals in particles of different sizes and under different weather conditions.Bioavailability of heavy metals in airborne particles was much higher than that in road dusts and soils,especially Pb(0.676 in airborne particles,0.159 in road dusts and 0.095 in soils).展开更多
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...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.展开更多
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 Ob...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.展开更多
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 ...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.展开更多
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...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.展开更多
This study explores how dust from the Ekati Diamond Mine potentially affects the availability and quality of forage on the seasonal range of the Bathurst caribou herd. Understanding the effects of dust as a source of ...This study explores how dust from the Ekati Diamond Mine potentially affects the availability and quality of forage on the seasonal range of the Bathurst caribou herd. Understanding the effects of dust as a source of disturbance is important because the Bathurst caribou population has declined by 93% since the middle 1980s and there are reports that caribou in general may avoid mining projects. There are several challenges for quantifying dust impacts: 1) Natural variations (e.g., topography, natural disturbance, and soil pH) may also impact forage availability and quality for caribou. To minimize their masking effect, we stratified survey sites into seven land cover classes and selected the most populous class (i.e., the dwarf shrub) for assessing the impact. 2) Within class variation (e.g., the proportion of area covered by rocks where vascular plants and lichen do not grow) can further skew the analysis. We eliminated this problem by examining only the area not covered by rocks. 3) Coarse and fine suspended particulates have different spatial coverages, chemical compositions, and pH values. Consequently, their impacts on caribou forage can be different. To distinguish their impacts, we sampled two areas: transects from the Misery Haul Road that has been in active use vs. those from a rarely used spur road outside the Misery Camp. We sampled percent vegetation cover, soil pH, and dust on leaves along these transects during the summers of 2015 and 2016. Our results indicated that the amount of dust on leaves in a zone of ~1000 m from the Misery Haul Road was 3 - 9 times than that of background sites. The zone of reduced lichen percent cover was also about 1000 m. In contrast, these road dust-induced changes in caribou forage were not observed for the dust-free transect from the spur road.展开更多
基金Project supported by the Natural Science Foundation of Beijing (No. 2063025) the Municipal Education Foundation of Beijing (No. KM200610028007)
文摘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.
文摘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<sup>-</sup>, Cl<sup>-</sup>, , , , Na<sup>+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, Ca<sup>2+</sup>, 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.
文摘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.
文摘This study analyzed the concentrations and chemical forms of Zn,Cu,Pb,Sb,Cd and Mn in airborne particles,road dusts and soils collected along three expressways in Jiangxi Province,China,with different traffic densities,and identified the levels and sources of heavy metal contamination.The concentrations of Zn,Cu,Pb,Sb,and Cd except Mn in airborne particles,road dusts and soils were all in direct proportion to traffic volume.Cd concentrations were low compared with other metals.For instance,the concentrations of Zn,Cu,Pb,Sb,Mn and Cd were 6.6,0.7,2.2,0.1,0.1 and 0.1μg·m-3in PM10along the Changjiu Expressway,792.8,241.4,248.3,9.6,340.5and 8.0 mg·kg-1in road dusts,and 201.1,143.2,59.5,9.5,338.9 and 2.3 mg·kg-1in soils,respectively,but in the case of the ratio of concentration to the environmental background value,most serious contamination was caused by Cd.The sources of the heavy metals were judged by comparisons of the chemical forms of the heavy metals in different environmental media.Pb and Mn in airborne particles were both derived from traffic;Pb in road dusts and soils resulted mainly from the use of leaded gasoline in the past;and Mn in road dusts and soils was derived from parent rocks.Zn,Cu,Sb and Cd in airborne particles,road dusts and soils were derived primarily from traffic,and differences in chemical forms of the heavy metals in different media were due to the interaction between heavy metals in airborne particles and organic matter and other surfaces in road dusts and soils.We also discussed the change of chemical forms of heavy metals in particles of different sizes and under different weather conditions.Bioavailability of heavy metals in airborne particles was much higher than that in road dusts and soils,especially Pb(0.676 in airborne particles,0.159 in road dusts and 0.095 in soils).
基金supported by the National Basic Research Program of China[973 program,grant number 2014CB441202]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA05100503]the National Natural Science Foundation of China[grant number 41021004],[grant number 41475137],[grant number 91544219]
基金supported by the National Key R&D Program of China (No. 2019YFC0214200)the National Research Program for Key Issues in Air Pollution Control of China (No. DQGG030405)the National Basic Science Research Program of the Chinese Research Academy of Environmental Sciences (No. JY21277132-201309406)
文摘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.
基金National Natural Scientific Foundation of China,No.41571473,No.41401591
文摘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.
基金the financial support by the National Natural Science Foundation of China (42042050, U2005207)Natural Science Foundation of Fujian Province, China (2020J0141)。
文摘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.
文摘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.
文摘This study explores how dust from the Ekati Diamond Mine potentially affects the availability and quality of forage on the seasonal range of the Bathurst caribou herd. Understanding the effects of dust as a source of disturbance is important because the Bathurst caribou population has declined by 93% since the middle 1980s and there are reports that caribou in general may avoid mining projects. There are several challenges for quantifying dust impacts: 1) Natural variations (e.g., topography, natural disturbance, and soil pH) may also impact forage availability and quality for caribou. To minimize their masking effect, we stratified survey sites into seven land cover classes and selected the most populous class (i.e., the dwarf shrub) for assessing the impact. 2) Within class variation (e.g., the proportion of area covered by rocks where vascular plants and lichen do not grow) can further skew the analysis. We eliminated this problem by examining only the area not covered by rocks. 3) Coarse and fine suspended particulates have different spatial coverages, chemical compositions, and pH values. Consequently, their impacts on caribou forage can be different. To distinguish their impacts, we sampled two areas: transects from the Misery Haul Road that has been in active use vs. those from a rarely used spur road outside the Misery Camp. We sampled percent vegetation cover, soil pH, and dust on leaves along these transects during the summers of 2015 and 2016. Our results indicated that the amount of dust on leaves in a zone of ~1000 m from the Misery Haul Road was 3 - 9 times than that of background sites. The zone of reduced lichen percent cover was also about 1000 m. In contrast, these road dust-induced changes in caribou forage were not observed for the dust-free transect from the spur road.
