ZHANG Weihua , HU Gongren, YU Ruilian, ZHANG Yuting, SU Guangming

（College of Chemical Engineering, Huaqiao University, Xiamen, Fujian 361021, China）

Abstract: Chemical species of heavy metals, including Fe, Mn, Cr, Cu, Ni, Pb, Zn, V and Sr, in surface and profile soil samples beside a national highway were investigated using a modified BCR extraction procedure combined with ICP-MS. The correlation between the chemical species of heavy metals and the soil properties was analyzed, and the bioavailabilities of heavy metals were evaluated by methods of the risk assessment code (RAC) and the ratio of secondary phase to primary phase (RSP). The results showed that concentrations of heavy metals in topsoil initially decreased and then increased with the distance from the road, and all the highest concentrations of heavy metals were found at 0~1 m away from the highway, indicating the significant effect of traffic. The concentrations of Cu, Zn, Mn, Pb and Sr in the vertical soil profile decreased with the increase of depth, and the peak values were mainly found at the 0~10 cm layer. The extractable proportions of Pb, Cu, Zn, Mn and Sr in topsoil were high at both ends and low in the middle of the distance from the roadbed, and the extractable proportions of Ni, Zn, Cu, Sr, Mn and V decreased downward along the soil profile. The concentrations of elements in different chemical forms correlated positively with their total amounts in soil, and there was a certain correlation, which is affected by the soil properties, among elemental concentrations of different chemical fractions. The RAC values of most heavy metals in the topsoil initially decreased and then increased with the distance from the road. The high risk of Zn, Sr and Mn occurred at 0~1m from the road, implying the great effect of traffic. Cu was significantly influenced by the traffic and a cement plant, Fe, V and Pb derived mainly from natural sources. The RAC values of elements in the soil profile decreased with the depth. The soil profile had been polluted by Cu, Sr, Ni and Zn in different degrees with the high risk mainly occurred in the surface layer. The risks of other natural derived heavy metals were relatively low.

Key words: national highway; soil; heavy metals; speciation; bioavailability

EARTH AND ENVIRONMENT Vol.47, No.2, Tot No.328, 2019, Page 151-160