城市道路旁小蜡叶片对重金属的富集特征

ACCUMULATION OF ATMOSPHERIC HEAVY METALS BY LIGUSTRUM SINENSE LEAVES IN URBAN TRAFFIC ROAD

通过对合肥市市区交通干线、城郊公路和植物园道路(对照区)的土壤,以及道路绿化灌木小蜡(Ligustrum sinense)叶片中Cu,Zn,Pb,Cd和Cr含量的测定,分析城市交通产生的大气重金属污染物在土壤和植物叶片中的富集特征.结果表明,公路交通和车辆尾气排放产生的重金属污染物能够显著地在土壤和小蜡叶片中富集.公路土壤中富集的Cu,Zn,Pb和Cr之间有着较高的相关性,且富集量与道路车流量有着明显的正相关.小蜡叶片富集的Cu,Zn,Pb,Cd和Cr主要来自于道路交通产生的大气重金属污染物,同土壤中相应重金属元素的相关性较差,而且市区干线的叶片富集量高于城郊公路,城郊公路高于对照点.雨水的冲刷能够减少小蜡叶片表面重金属的含量,同时小蜡叶片对重金属的富集,在4月至7月的富集速度或富集增量高于7月至10月,这与小蜡叶片的生长趋势相一致.

The relationship between atmospheric heavy metal contaminations caused by road traffic and concentration of Cu, Zn, Pb, Cd and Cr in leaves of Ligustrum sinense, roadside soils were revealed in selected urban trunk road, suburban road, and botanical garden road as the background reference site in Hefei city. Leaves of L. sinense were sampled in April, July and October while soils collected only in July. Analyses for contents of metallic elements mentioned above using flame atomic absorption spectrophotometry showed obvious concentration of heavy metals in soils and leaves of L. sinense related with road traffic. A positive correlation between Cu, Zn, Pb, Cr in roadside soils indicated a common origin of these elements. Heavy metals contents in leaves and trunk road soil were much higher than the ones of suburban road and reference site due to atmospheric contamination significantly correlation with traffic currents, even met the significant level. It was found leaves of L. sinense could absorb much more heavy metals from April to July than July to October, this phenomenon correctly accorded with the growth character of L. sinense.