Abstract:

Aim Roadside soils can be polluted by heavy metals from traffic exhaust. These heavy metals can be absorbed by plants, pass through food chains and ultimately harm humans. Our objectives were to investigate spatial distribution, accumulation and contamination of heavy metals (Pb, Cd, Zn, Cr and Cu) in a roadside soil-wheat system and assess the health risk of heavy metals for persons eating the wheat.

Methods We collected samples of soils, wheat seedlings and wheat seeds at different distances from the road edge in the Putian section of Zhengzhou-Kaifeng highway. Soil samples were digested with HCI-HNO3-HF-HClO4. Plant samples were digested with a dry incineration method for Cu, Zn and Cr and the HNO3-HClO4 method for Pb and Cd. Cr, Cu, and Zn in soil and plants were determined by flame atomic absorption spectrometry, while Pb and Cd were determined by graphite furnace atomic absorption spectrometry.

Important findings Heavy metal concentrations in the samples initially increase and then decrease with the distance from the road. Concentrations in soils are higher than that in wheat seedlings, and the concentrations in wheat seedlings are higher than that in wheat seeds. The enrichment coefficient order of heavy metals in wheat seeds and seedlings is Cu>Cd >Zn>Pb>Cr, and the coefficients of the seedlings are higher than those of the seeds. The cadmium health risk of eating wheat seeds is critical, but there are no health risks from copper, lead and zinc in all samples.

Key words: Zhengzhou-Kaifeng highway, soil-wheat system, heavy metal accumulation, heavy metal pollution, health risk assessment of heavy metals