Spatial Distribution and Contamination of Heavy Metals in Road Dust,Sediment in Roadside Ditch and Roadside Soils along Zhengzhou-Kaifeng Highway

To understand the spatial distribution and contamination of heavy metals along roads and roadsides,Zhengzhou-Kaifeng highway,having operated over 40 a,was chosen as the research object.A sampling transect is perpendicular to the highway.Samples were collected on the line of this transect at a specific interval.The concentrations of Ni,Cu,Zn and Cr in these samples were determined by the flame atomic absorption spectrometry(F-AAS),and Pb and Cd by the graphite furnace atomic absorption spectrometry(GF-AAS).The research results show that heavy metals,except for Ni in road dust,sediment in roadside ditch,and roadside soils along the highway,have accumulated obviously because of trail gas from vehicles,wearing of engine and brakes,and wearing between tires and road surface.The heavy metal concentrations in road dust and roadside soils on the northern side of the highway are higher than those on the southern side.The concentrations of most heavy metals in the road dust are lower than those in the sediments in roadside ditch,but higher than the average values in the control samples and roadside soils within 300 m from the highway.The highest concentrations of most heavy metals,except for Cu in soils,are at 20 to 50 m away from the roadbed, and then gradually decrease to the control values.The incidence of highway traffic exceeds over 300 m from the highway.The zones within 100 m from the roadbed have been moderately or heavily polluted by heavy metals,and Cd,Cr and Pb are the main pollutants originated from the highway.