Heavy Metals In Roadside Soils Research Articles

Evaluation of Heavy Metals in Roadside Soil of Tumfure Main Market, Gombe State

Heavy metal pollution has been a problem of concern in soil ecology in recent decades. This study evaluated the physico-chemical characteristics and heavy metal contents in roadside soil samples of Tumfure main market, Gombe, Nigeria. The soil samples were collected from six different sampling points with a control sample each by handpicking, this was followed by oven-drying, ground to fine grain, and then sieved using a 2 mm mesh sieve. The pH, electrical conductivity and bulk density were carried out on the soil samples, sieve and sedimentation method were used to determine the soil texture. The soil samples were weighed and digested using mixture of HCl and HNO3. The contents (mg/kg) of four metals (cadmium, copper, lead and zinc) were estimated using Atomic Absorption Spectrophotometer (AAS). Among the metals analyzed, the contents of Cd, Cu and Pb were not detected while the content of Zn (23.454 - 36.026) was found to be within the desirable permissible limits by the World Health Organization (WHO) and European Regulatory Standards (EURS) whose prevalence is to be considered non-toxic in unpolluted soils.

Spatial Distribution, Risk Assessment and Sources of Heavy Metals in Roadside Soils Exposed to the Zhengzhou-Kaifeng Intercity Railway in Huanghuai Plain, China

ABSTRACT Heavy metal accumulation in soil can seriously harm human health, and it is necessary to identify the accumulation status and access the potential risks for local pollution control and sustainable economic development. This study evaluated the pollution level, spatial distribution, potential risk and sources of soil heavy metals along the Zhengzhou-Kaifeng intercity railway and compared pollution characteristics in north side soils with south side soils of the railway. A total of 260 soil samples were collected from a section along the railway. In practice, only the average Zn and Pb contents in soils were slightly higher than their corresponding risk screening values. The heavy metal enrichment in the north side soils was marginally lower than that in the south side soils. The spatial distribution of soil heavy metals except Pb could be mainly influenced by the different land use types. The geoaccumulation index and potential ecological risk of a single heavy metal indicated that Cd was the major contaminant with moderate pollution and high ecological risks in the south side soils and none to moderate pollution and moderate ecological risks in the north side soils. However, the mean multimetal potential ecological risk values suggested that the north side soils were at low ecological risks and the south side soils were at moderate ecological risks. The comprehensive non-carcinogenic risks and total carcinogenic risks for adults were low and acceptable, respectively. Pearson correlation analysis, PCA, and APCS-MLR analyses identified that the contributions of natural sources, mixed sources of industrial and traffic activities, agricultural activities, and other sources were 57.49%, 21.44%, 12.67% and 8.40%, respectively, and the major soil pollution Cd was mainly related to mixed sources of industrial and traffic activities. Therefore, continuous soil heavy metal monitoring is essential to elucidate the long-term railway operation effect on soil heavy metal accumulation.

Ecological and health risk assessment of heavy metals in roadside soil, dust and water of three economic zone in Enugu, Nigeria

Heavy metals posed threat to humans and environment. Spatial distribution/source identifications of heavy metals in soil, dust and water along major road of three economic zone of Enugu: Enugu/PH road (Industrial area), Agbani Road (Residential) and Ogui New Layout Road (Commercial) were evaluated. Soil and dust samples were collected at 15 cm depth and 1 m from roads, underground water at 65 m from roadside between December 2020–April 2021. Heavy metals were quantified by AAS. Heavy metals (mg/kg) in roadside soil varied from 0.00 to 0.05 (Cr), 1.50–4.00 (As), 0.08–6.93 (Ni), 4.98–7.86 (Cu), 0.00–0.03 (Hg), 213.95–274.79 (Fe), 1.25–4.16 (Pb) and 8.49–16.23 (Mn) for Enugu/PH; 0.00–0.20 (Cr), 2.75–3.13 (As), 0.25–4.94 (Ni), 3.65–11.73 (Cu), 0.00–0.00 (Hg), 159.87–233.65 (Fe), 2.08–4.54 (Pb), 6.18–17.15 (Mn) for Agbani; 0.00–0.13 (Cr), 1.48–3.70 (As), 0.03–1.50 (Ni), 3.13–5.54 (Cu), 0.00–0.00 (Hg), 138.06–189.51 (Fe), 0.58–1.38 (Pb), 9.75–21.75 (Mn) for Ogui. The level of heavy metals (mg/kg) in roadside dust ranged from 0.00 to 0.18 (Cr), 0.00–2.33 (As), 0.85–2.05 (Ni), 4.54–16.93 (Cu), 0.00–0.00 (Hg), 137.36–247.03 (Fe), 0.88–4.99 (Pb), 17.65–26.43 (Mn) for Enugu/PH; 0.00–0.00 (Cr), 0.00–2.85 (As), 0.71–4.68 (Ni), 4.94–121.85 (Cu), 0.00–0.00 (Hg), 159.23–203.70 (Fe), 0.59–14.63 (Pb), 15.05–23.44 (Mn) for Agbani; 0.00–0.14 (Cr), 0.00–2.33 (As), 1.08–4.45 (Ni), 4.25–6.95 (Cu), 0.00–0.00 (Hg), 152.84–207.66 (Fe), 1.00–3.41 (Pb), 14.13–23.18 (Mn) for Ogui. As in water Enugu/PH (0.081 mg/L), Agbani (0.079 mg/L) and Ogui (0.150 mg/L). Principal component analysis indicated that Cr, As, Ni, Cu, Hg, Pb Fe and Mn distributions were affected by traffic, industrial release and natural sources, ecological analysis showed low to moderate pollution. Risk assessment (children/adults) via each pathway were HI <1. Estimated cancer risk of 75% heavy metals via CRing/inh/der (soil, dust water) below 1× 10−6 - 1 × 10−4, total cancer risk shows high probability of carcinogenic risk via ingestion as children > adult susceptibility on prolonged exposure to vehicular activity, hence alarming contamination status of heavy metals in Enugu and associated health risk.

The Concentrations, Sources, Ecological, and Human Health Risk Assessment of Heavy Metals in Roadside Soils of Six Cities in Shanxi Province, China.

Roadside soils are regarded as a reservoir for heavy metal pollution, which potentially leads to ecosystem deterioration as well as serious hazard to human health. A comprehensive investigation was conducted for the levels, relationship with soil properties, and potential sources of heavy metals (Hg, Cu, Zn, Pb, Cd, and Cr) in roadside soils in six cities (Changzhi, Jincheng, Yuncheng, Linfen, Xinzhou, Datong) of Shanxi Province; and the corresponding ecological risk and human health risk associated with the concentrations of heavy metals were addressed. Heavy metal concentrations of 112 roadside soil samples in the surveyed cities were, in decreasing order, Zn, Cu, Cr, Pb, Cd, and Hg, which were higher than corresponding background values. The highest concentrations were in Changzhi. The results of Pearson correlation analysis demonstrated that positive correlations in varying degrees existed between soil properties such as electrical conductivity, total nitrogen, total phosphorus, and total organic carbon with specific heavy metals and that negative correlations were observed for clay and electrical conductivity. Anthropogenic sources related to traffic emissions and industrialization were the main sources of heavy metals in roadside soils according to principal component analysis. The ecological risk assessments were achieved by pollution index and potential risk index, indicating that contamination with Hg was the most serious, which posed the highest risk to the ecosystems in the surveyed cities; and the ecological risk in Changzhi ranked at the top compared with other cities. For the human health risk assessment, the results demonstrated that the noncarcinogenic and carcinogenic risks were in the acceptable range in the surveyed cities. However, there was a higher health risk from heavy metal exposure for children than adults, and the main exposure pathway was soil ingestion. In addition, Changzhi was the city with the highest noncarcinogenic and carcinogenic risks, and the main human health risks were posed by Cr contamination in roadside soil, which was different from the results of ecological risks. Both results of ecological and health risk assessment demonstrated that the higher risk exhibited in southern and southeastern cities than northern cities in Shanxi Province. Environ Toxicol Chem 2023;42:1485-1500. © 2023 SETAC.

Assessing the overwhelming metals in roadside soils of fundamental roads in Jos city, Nigeria

Studying the heavy metals in roadside soils is very important in evaluating the probable automobile emission’s environmental effects on the soil. To conduct the study, the soil samples were gathered and examined for the Pb, Zn, Mn, Cu, Ni, Cd, Co and Fe levels by the use of AAS. It was found that the order of the mean total metal content for the examined metals: Fe &gt; Zn &gt; Mn &gt; Pb &gt; Cd &gt; Cu has a decreasing trend. Other than Cd, it was reported that all metals are lower compared to the levels of those found in other studies. Not involving Co and Ni shows that there is no pollution because of such metals. A correlation analysis was performed between metals and the traffic volume (V), indicating that there is a significant positive correlation (p &lt; 0.05) between Pb, Cd and Mn, and V. In addition, the vehicular emissions are the main reason for originating the metal pollution in the soil for example motor vehicles. For this reason, the present study presents an applied approach to control the level of such metals.

Road Construction and Trace Heavy Metals in Roadside Soils along a Major Traffic Corridor in an Expanding Metropolis

City growth often time results in advancement and development in transportation which comes with its attendant changes in road infrastructure and transport support services such as road side mechanic workshops, vulcanizers and bus stops. A byproduct of these attendant contiguous activities and processes is the emission and release of trace heavy metals. Trace heavy metals have been identified as major carcinogens. This study aimed at determining the occurrence and concentration of heavy metals in roadside soils in an expanding third world metropolis. To achieve the aim of the research, the total length of the road within the study section was measured. Ten sample locations were indentified at about 2.5km intervals along the road section under review. The heavy metal concentration was determined the using Buck Scientific 210 VGP Atomic Absorption Spectrophotometer. Heavy metals such as Iron (Fe), Copper (Cu), Cadmium (Cd), Lead (Pb) and Mercury (Hg) were determined. The result of the analysis showed that the concentration values ranged from &lt;0.001 to 48.90 µg/mg. The results also revealed that the experimental sample points recorded higher values than the control samples; however, some of the control points had relatively higher concentration values. This observation may have emanated from the low lying trajectory and topography of the surrounding area, which allows run-off from the road side soils to wash off heavy metals and deposit them at these lower lying areas. The sources of these trace heavy metals are attributed to emissions from motor vehicles that ply the road on a day to day basis. Emanating from the findings, this study recommends that improved public transportation and cleaner sources of energy is recommended.

Determination of Some Heavy Metals in Roadside Soils from Some Major Roads in Maiduguri, Borno State, Nigeria

Heavy metal concentration in road side soils with its potential ecological effects draws much attention in the developing countries. This necessitates the study of their accumulation in the road side soils of Maiduguri (longitude 11° 13’ N; latitude 13° 05’ E), to ensure effective protection of soil from the potential loss of its fertility. In this study, roadside soil samples from major roads (Baga road, Bama road, Ngala road and Kano/Jos road) of Maiduguri were collected and determined the levels of heavy metals (As, Cr, Mn, Fe, Ni, Pb, Zn, Cd, and Cu) in the roadside soil using the Perkin-Elmer analyst 300 Atomic Absorption Spectroscopy (AAS). The results showed that in all the sampling locations, Mn, Zn, Fe and Pb have higher concentration of 137.4±0.04 mg/kg, 392.11±0.07 mg/kg, 13491.70±0.07 mg/kg and 928.50±0.04 mg/kg respectively in roadside soil as compared with Cd of concentration ranges from 0 to maximum of 0.87±0.04mg/kg in Ngala road. The concentrations of Pb and Cd in the soil samples were higher than the recommended value of 48 mg/kg and 5.0 mg/kg respectively. The higher concentration of these metals in the roadside soil samples may be attributed to human activities and traffic volume. Therefore, there is need to further study the concentrations of such heavy metals in agricultural soil, plants and vegetables grown in that area, animals that fed on the plants and any other source that directly or indirectly link to the source of food of the populace.

Chemical Speciation, Bioavailability and Risk Assessment of Potentially Toxic Metals in Highway Dusts as Indicators of Highway Pollution

This paper investigated concentrations of heavy metals in roadside soil dusts collected along Ife-Ibadan highway in Osun state, Nigeria with the aim of assessing the impacts of vehicular emissions on the environments. The soil dusts were analyzed for total metal concentrations and speciation using Atomic absorption spectrophotometry followed by the evaluation of the metal bioavailability. Results of the total metal analysis indicated that the concentrations of the metals (Pb, Zn, Cu, Fe and Mn) were higher in the contaminated soils than control soils and their WHO maximum allowable limits. The pattern of the total mean concentrations of the metals is in the order: Fe > Cu > Mn > Zn > Pb. The contamination factors of the metals showed that the soils suffered contamination. Analysis of variance (ANOVA) revealed that differences existed significantly in the mean values for all the metals across the study sites. Strong correlation among the metals signified common contamination sources. Cluster analysis produced two major groups: A (Fe and Cu) and B (Zn, Mn and Pb) which is subdivided into two sub-groups viz: Bi (Zn and Mn) and Bii (Pb), indicating similar chemical properties/or sources. The results of the T–test indicated that there were significant differences between the concentrations of the metals in contaminated and control soils. The chemical pools of the metals indicated that the metals were distributed into six fractions with most of the metals residing in the non-residual fractions, suggesting how readily the metals are released into the environment.

Geo-environmental study of heavy metals of the agricultural highway soils, NW Jordan

This study investigated the status and distribution patterns of selected heavy metals in roadside soils along Irbid-North Shooneh Highway, Jordan. This highway has experienced a growing number of vehicles that are likely to influence the levels of heavy metals in the surrounding agricultural lands. The average concentrations of Cr, Co, Cd, Cu, Pb, Zn, and Ni were 16.0, 36.0, 11.0, 4.0, 79.0, 122.0, and 60.0 mg/kg, respectively. Cd, Pb, and Co showed average levels that are higher than the average world soil background values. Elevated levels of heavy metals were measured in surface soil layer which decreased with depth, and with distance from the roadway. The contamination factor (CF), pollution load index (PLI), single ecological risk (Ei), potential ecological risk index (PERI), and geo-accumulation index (Igeo) generally indicated that the roadside soils are contaminated with Cd, Pb, and Ni. Heavy metals in soils are of geogenic and anthropogenic origins. Weathering of parent rocks in Wadi Al-Arab catchment is the primary natural source, whereas agrochemicals, vehicle exhausts, degradation of surface wear and paint of vehicles, vehicle wear debris of tire, and brake lining are the main anthropogenic sources of heavy metals.

Ecological risk assessment of some heavy metals in roadside soils at traffic circles in Gombe, northern Nigeria

The study evaluated the levels of some heavy metals in the roadside soils at different traffic circles using geo-accumulation index, ecological risk and Hakanson method to assess the overall ecological risk and identify ecological potential risk of heavy metals pollution. The top soil samples were collected at three different traffic circles from edge and at 50 m distance from the roadside, and analysed for heavy metal (Pb, Cd, Cu and Zn) using atomic absorption spectrophotometer. The mean concentrations of heavy metals (mg/kg) ranged from (15.0 - 45.07) Pb, (0.35 - 2.60) Cd, (19.05 - 38.0) Cu and (58.10 - 101.0) Zn. The abundance of metals was found in declining order: Zn > Pb > Cu > Cd. The metals concentrations were found to be higher in the soil samples from edge due to high traffic volume and human activities, and there was significantly decrease in concentration with increase in roadside distance. The Geoaccumulation index (I geo ) examined in this study revealed that soil samples from edge and 50 m distance from the roadside were polluted with cadmium. Ecological risk assessment carried out showed that the metals posed low ecological risk and cadmium contributed 66.63 - 94.21% of the total potentially ecological risk. Keywords: Assessment, Ecological risk, Heavy metals, Roadside soil

Accumulation of Heavy Metals in Roadside Soil in Urban Area and the Related Impacting Factors.

Heavy metal contamination in roadside soil due to traffic emission has been recognized for a long time. However, seldom has been reported regarding identification of critical factors influencing the accumulation of heavy metals in urban roadside soils due to the frequent disturbances such as the repair of damaged roads and green belt maintanance. Heavy metals in the roadside soils of 45 roads in Xihu district, Hangzhou city were investigated. Results suggested the accumulation of Cu, Pb, Cd, Cr, and Zn in roadside soil was affected by human activity. However, only two sites had Pb and Zn excessing the standards for residential areas, respectively, according to Chinese Environmental Quality Standards for soils. The concentrations of Cu, Pb, Cd, and Zn were significantly and positively correlated to soil pH and organic matter. An insignificant correlation between the age of the roads or vegetation cover types and the concentration of heavy metals was found although they were reported closely relating to the accumulation of heavy metals in roadside soils of highways. The highest Pb, Cd, and Cr taking place in sites with heavy traffic and significant differences in the concentrations of Cu, Pb, Cd, and Zn among the different categories of roads suggested the contribution of traffic intensity. However, it was difficult to establish a quantitative relationship between traffic intensity and the concentrations of heavy metals in the roadside soil. It could be concluded that impaction of traffic emission on the accumulation of heavy metals in roadside soils in urban area was slight and soil properties such as pH and organic matters were critical factors influencing the retention of heavy metals in soils.

Distribution and Ecological Risk Assessment of Heavy Metals in Roadside Soil along the Hemat Highway of Tehran, Iran

Distribution and Ecological Risk Assessment of Heavy Metals in Roadside Soil along the Hemat Highway of Tehran, Iran

Sources, Transport Pathways and the Ecological Risks of Heavy Metals present in the Roadside Soil Environment in Urban Areas

The study investigated the sources and transport pathways of heavy metals in roadside soils in urban areas of a typical nodal city, alongside the associated eco-risks. Soil, leaf and bark samples were collected along the routes and analyzed for metal concentration using standard methods. The data were analyzed using ANOVA, Principal Component Analysis and Factor Analysis. The results showed that Pb, Cu and Ni in the roadside soil were found to be mainly from traffic emissions, whereas Cd in the soil was primarily through municipal waste incineration. Pb, Cd and Ni in leaf samples were absorbed from the soil via foliar uptake, while root uptake was the primary pathway for Cu in the leaves. Potential ecological risk indicated moderate eco-risk for 5 routes with Cd being the primary contributor to the risk. Therefore, it is important to control the source of Cd to reduce the eco-risks associated with metal pollution.DOI: http://dx.doi.org/10.5755/j01.erem.73.3.18754

Occurrence and Distribution of Heavy Metals in Roadside Soils and Plants along Major Urban Roads of Zanzibar

Occurrence and Distribution of Heavy Metals in Roadside Soils and Plants along Major Urban Roads of Zanzibar

Metal accumulation in roadside soil in Melbourne, Australia: Effect of road age, traffic density and vehicular speed

Concentrations of vehicular emitted heavy metals in roadside soils result in long term environmental damage. This study assessed the relationships between traffic characteristics (traffic density, road age and vehicular speed) and roadside soil heavy metals. Significant levels were recorded for Cd (0.06–0.59 mg/kg), Cr (18–29 mg/kg), Cu (4–12 mg/kg), Ni (7–20 mg/kg), Mn (92–599 mg/kg), Pb (16–144 mg/kg) and Zn (10.36–88.75 mg/kg), with Mn concentrations exceeding the Ecological Investigation Level. Significant correlations were found between roadside soil metal concentration and vehicular speed (R = 0.90), road age (R = 0.82) and traffic density (R = 0.68). Recently introduced metals in automotive technology (e.g. Mn and Sb) were higher in younger roads, while the metals present for many years (e.g. Cd, Cu, Pb, Zn) were higher in medium and old age roads confirming the risk of significant metal deposition and soil metal retention in roadside soils.

Health risk assessment of heavy metals in roadside soil along the Hemmat Highway of Tehran, Iran, in 2014

Health risk assessment of heavy metals in roadside soil along the Hemmat Highway of Tehran, Iran, in 2014

Identification of traffic-related metals and the effects of different environments on their enrichment in roadside soils along the Qinghai–Tibet highway

The road transportation could affect roadside soils environment detrimentally, including heavy metal enrichment. In order to identify and evaluate the enrichment of heavy metals resulted from road transportation on the Tibetan Plateau, the 11 heavy metals (V, Cr, Co, Ni, Cu, Zn, As, Cd, Rb, Pb and Tl) in the topsoil (0–10 cm depth) from four sites along the Qinghai–Tibet highway were discussed in this study. Our results indicate that heavy metals such as Cr, Cu, Zn, As, Cd and Pb are related to road transportation. The content of most of these heavy metals in roadside soils decreased exponentially with the distance from the road, as did some of the Nemero Synthesis Indexes (PN values). The contamination factor for the traffic-related metals ranged from 0.56 (no pollution) to 5.67 (considerable pollution) and the Nemero Synthesis Indexes of these heavy metals ranged from 0.80 (no pollution) to 4.49 (severe pollution). Cd was of priority concern as it had the highest contamination factor. The highest PN value for these traffic-related heavy metals was found in soils at site TTH (alpine steppe). Although transportation contributed to the high contents of these traffic-related metals in roadside environments, regional differences such as wind and the terrain also had significant relationship with their enrichment in these roadside soils. The roadside distance at which there is a potential risk to livestock and wildlife from the contamination of soils by heavy metals should be determined scientifically along the Qinghai–Tibet highway, based on the different natural environments found in the region.

Analysis of Roadside Dust for Heavy Metal Pollutants in Jimeta/Yola Adamawa State, Nigeria

A study of heavy metals in roadside soils is critical in assessing the potential environmental impacts of automobile emission on the soil. This study is aimed at analyzing heavy metal pollutants that may be present in roadside dust samples in Jimeta/ Yola, Adamawa State, Nigeria. Dust samples were collected around mechanical workshops (MWK), motor parks (MPK), market areas (MKA), roundabouts/highways (RHW) and residential areas (RDA). The dust samples were digested using aqua regia digestion method and Atomic Absorption Spectrophotometer was used for the heavy metal analysis. The change in concentration of most of the heavy metals determined from different sites decreases in the following order MWK>MPK>MKA>RHW>RDA. The heavy metals reveal a variation which indicates Fe>>Zn>Pb>As>Cu>Ni>Cr>Cd. Iron had the highest concentration in all the sampling areas with range of 3460±198 - 5800±50 µg/g. A lower value was observed for Cd with respective range of 0.48±0.05 - 1.74±0.06 µg/g. Cobalt and selenium were not detected in all the samples. Statistical analyses by ANOVA showed a significant difference (P<0.05) between the elements determined. This suggested that, the heavy metal pollutants in the roadside dust samples of Jimeta /Yola did not originate from common anthropogenic sources. Probably automobile emission due to traffic density, welding of metal and exhaust from power generators may have contributed to the presence of these elements in the roadside dust environment.

Relationship between Heavy Metal Concentrations in Soils and Grasses of Roadside Farmland in Nepal

Transportation activities can contribute to accumulation of heavy metals in roadside soil and grass, which could potentially compromise public health and the environment if the roadways cross farmland areas. Particularly, heavy metals may enter the food chain as a result of their uptake by roadside edible grasses. This research was conducted to investigate heavy metal (Cu, Zn, Cd, and Pb) concentrations in roadside farmland soils and corresponding grasses around Kathmandu, Nepal. Four factors were considered for the experimental design, including sample type, sampling location, roadside distance, and tree protection. A total of 60 grass samples and 60 topsoil samples were collected under dry weather conditions. The Multivariate Analysis of Variance (MANOVA) results indicate that the concentrations of Cu, Zn, and Pb in the soil samples are significantly higher than those in the grass samples; the concentrations of Cu and Pb in the suburban roadside farmland are higher than those in the rural mountainous roadside farmland; and the concentrations of Cu and Zn at the sampling locations with roadside trees are significantly lower than those without tree protection. The analysis of transfer factor, which is calculated as the ratio of heavy-metal concentrations in grass to those in the corresponding soil, indicates that the uptake capabilities of heavy metals from soil to grass is in the order of Zn > Cu > Pb. Additionally, it is found that as the soils’ heavy-metal concentrations increase, the capability of heavy-metal transfer to the grass decreases, and this relationship can be characterized by an exponential regression model.

Spatial Distribution and Potential Ecological Risk Assessment of Heavy Metals in Roadside Soils on Different Operated Times along the Lianyungang-Horgas Highway

Wanliu and Xiaowangzhuang transects which operated in 1994 and 2001 respectively along Zhengzhou-Shangqiu section on Lianyungang-Horgas highway were chosen to investigate heavy metal (Cd, Cu, Pb, Zn, Ni, and Cr) pollution and potential ecological risks of roadside soils. Concentrations of soil heavy metals on Wanliu transect were higher than that on Xiaowangzhuang transect. The content of soil heavy metals increases with the distance away from highway, reaching a maximum value, and then decreases gradually. Potential ecological risks of the soil metals are at moderate level on Wanliu transect, while slight level on the other transect. Concentrations of most soil heavy metals and their potential ecological risks present skewness distribution with the distance form highway roadbed. The highest risk indexes (RI) for different metals on Wanliu transect are among 50 ~100 m from highway roadbed, farther than that on Xiaowangzhuang transect at 35 m. Most of the soil samples on northern side of the highway show higher metal concentrations and potential ecological risks than that on southern side. The total risk index was contributed by the heavy metal of Cd (averagely 61.39%), which is the main factor of potential ecological risks. The grade standards for different ecological risk levels must be modified according to types and amount of pollutants studied and their toxic-response factors.