Abstract:

Mass fractions of heavy metals (Pb,Cd,Cu,Zn,As) were measured in surface soil and 19 plant leaves in forests along both sides of Hailin to Yabuli section of Suiman highway in Heilongjiang Province. The mass fraction characteristics of five heavy metals in soil-vegetation system in the roadside were studied. The results showed that the mean mass fraction of 5 heavy metals was higher than the background value. The heavy metals pollution of the soil was evaluated by using single factor pollution index and integrated pollution index，the results showed that Cu,Cd,Pb,Zn and As had contaminated the soil, and the contaminated level of Cu,Pb,Zn and As reached lightly polluted，while Cd contamination was severer. The integrated pollution index showed the contaminated level reached to moderate pollution. But mass fraction of heavy metals was lower than national grade Ⅱ standard except Cd, which was one of the main pollutants of traffic pollution. Cd mass fraction gradually decreased in plant leaves, and increased and then decreased in the soil, with the distance apart from the highway. Moreover, the contaminated area of soil-vegetation system reached to 40～60 m of the forests from the highway. Suitability evaluation of 19 plant species to the heavy metals pollution was also comprehensively studied in this paper. It was found that the excellent tree species for preventing from the heavy metal pollution along both sides of the highway were Quercus mongolica,Betula platyphylla and Abies nephrolepis, which were able to grow well on the contaminated environment and accumulate high contents of the heavy metals. The other tree species such as Ulmus propinqua,Ulmus laciniata,Alnus hirsute,Philadephus schrenkii,Sorbaria kirilowii,Lonicera maacki were also suitable to grow in the region with the moderate pollution.

Key words: Suiman highway, forest, soil and vegetation, heavy metals