Abstract:
Objective The paper aims to clarify the spatial distribution characteristics and influencing factors of heavy metals in soils around highways for the prevention and control of soil heavy metals pollution and agricultural safety production along the highways.
Method Four highways (Shanghai-Nanjing Highway, Beijing-Shanghai Highway, Nanjing-Nantong Highway and Lianyungang-Huoerguosi Highway Jiangsu Section) were selected as the case study areas. The heavy metal contents were measured using high-precision soil heavy metal rapid detector (X-Ray fluorescence spectroscopy, XRF). The distribution characteristics of heavy metals in soil around highway were analyzed. On this basis, the influencing factors of heavy metal distribution in soil around highway were explored.
Result ① The Cd, Pb, Cu, and Zn in surface soils along the highways were generally higher in the south and lower in the north, the distribution characteristics of the north-south direction was smaller than that of the east-west direction, and the soil Cd at some sites exceeded the risk screening values for soil contamination of agricultural land. ② The distance from the road shoulder affected the content of heavy metals in the soil on both sides. The main influence range was within 50 m. The soil heavy metal contents varied greatly under different land use types.
Conclusion The heavy metals were mainly accumulated in the surface soils, especially for Cd. The heavy metals in the deep soils were less affected by road traffic. The soil on both sides of the road was affected by the distance from the road shoulder, land use types, road age and traffic flow. The longer the road age, the greater of the soil heavy metal enrichment coefficient. Planting shelterbelts with different ranges of green belts on both sides of the highways can better prevent and control the spread and risk of heavy metals in farmland soils.
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