城市交通大气与土壤重金属对小蜡生物富集作用的影响

Bioaccumulation Effect in Ligustrum Sinense Affected by Urban-Traffic Atmosphere and Soil Heavy Metals

选择合肥市区交通干道、城郊公路和森林公园作为具有不同交通流量的路段,通过火焰原子吸收法,测定土壤和小蜡叶片中的w(Cu),w(Zn),w(Pb),w(Cd)和w(Cr);运用统计方法研究土壤和小蜡叶片中重金属含量的差异和相关性,以及与城市交通大气污染的关系.结果表明:市区交通干线和城郊公路的土壤中w(Cu),w(Zn),w(Pb),w(Cd)和w(Cr)均高于对照点(森林公园),且市区交通干线与对照点的土壤中重金属含量差异显著;小蜡叶片对5种重金属富集量与土壤中的相应重金属含量没有明显相关性,这表明叶片富集的重金属主要来源于道路交通产生的大气重金属污染物,而非主要从土壤中吸收获得;小蜡叶片对大气中的Pb和Cr的富集能力较强,其生物浓缩系数分别为5.50和3.43,说明小蜡可能是Pb和Cr的良好指示植物,可用于环境监测.

The relationship between urban-traffic atmosphere and concentration of Cu, Zn, Pb, Cd, Cr in leaves of Ligustrum Sinense and associated soils in selected urban trunk road, suburban road and the presumed unpolluted reference site, botanical garden were revealed in Hefei City, Anhui Province. Analyses of soils and/eaves samples by determined contents of the metallic elements using flame atomic absorption spectrophotometry, pointed to obvious concentration of heavy metals in soils and leaves related with urban traffic. Soil heavy metals contents of Cu, Zn, Pb, Cd, Cr in trunk road and suburban road were much higher than the reference site, and even met the significant level in trunk road by statistical test. The negative relationship was found between contents of heavy metals in leaves and soils within experiment areas. This result clearly showed heavy metals in leaves of Ligustrum Sinense were mostly accumulated from urban-traffic emitted atmospheric metallic contaminations unless mainly absorbed from soil. The higher bioconcentration factors of Pb and Cr respectively as 5.50 and 3.43 were found in L. Sinense leaves compared with Cu, Zn and Cd elements, indicated that this shrub plant had stronger bioaccumulation ability to Pb and Cr and may be used for monitoring aerial Pb and Cr contaminations in environment.