北京常见绿化树种叶片富集重金属能力研究

Beijing Common Green Tree Leaves' Accumulation Capacity for Heavy Metals

以北京地区常见绿化树种为研究对象,测定叶片和土壤重金属含量,对其季节变化规律和污染程度的相关性进行分析,探究植物叶片对土壤中重金属的富集能力.结果表明:①植物叶片中重金属Cu、Pb、Zn含量随季节变化(由春到冬)呈先下降后升高再下降的变化趋势;Cr含量变化呈先升高后下降的趋势,秋季达最高值;春、夏、秋这3季对Cu富集能力较强的为柳树和国槐,冬季为油松;对Cr、Pb富集能力较强的是国槐和侧柏,冬季为侧柏和白皮松;对Zn富集能力较强的为柳树和白皮松,冬季为侧柏;②由市中心至远郊,4种重金属(Cu、Cr、Pb、Zn)污染程度为:景山(C=2.48,C为污染系数)>奥林(C=1.27)>松山(C=1.20)>水关(C=1.18);③水关长城景区植物叶片中重金属含量变化较大,其它3个研究区域重金属含量排序为:景山>奥林>松山;同一树种叶片对不同重金属富集能力排序均为:Zn>Cu>Pb>Cr,且Zn含量与Cr含量差异极显著(P<0.01);④植物叶片中重金属含量与土壤中相应重金属元素污染程度呈二次多项式关系,除Cu元素外,其余3种重金属元素含量与土壤中重金属污染程度相关性较强,且相关系数均达0.9以上.

Seasonal variation of heavy metal contents in leaves and their relationships with soil heavy metal pollution levels were studied through measuring and analyzing the leaves of the common tree species in Beijing and soil heavy metal contents,to detect heavy metal accumulation ability of plant leaves. The results showed that: ① the contents of Cu,Pb,Zn in plant leaves first decreased and then increased,again declined with changing the seasons( from spring to winter). Cr concentration showed the trend of first increase and then decrease from spring to winter,and the highest in the autumn; the accumulation capacities of Cu for Babylonica and Japonica were higher in the spring,summer and autumn,while Tabuliformis was in winter; the higher accumulation capacities for Cr,Pb were Japonica and Platycladus,and in winter were Platycladus and Bungeana; the higher accumulation capacities for Zn were Babylonica and Bungeana,while Platycladus in winter; ② the pollution degree of four kinds of heavy metals( Cu,Cr,Pb,Zn) from downtown to suburbs showed that: Jingshan( C = 2. 48,C is contamination factor) > Olympic( C = 1. 27) > Songshan( C = 1. 20) > Shuiguan( C = 1. 18); ③ the heavy metals concentration of same plant leaves in the water of the Great Wall changed larger,but those in the other three areas showed that: Jingshan > Olympic > Songshan; the ability of same species leaf to absorb different sorts of heavy metals showed that: Zn > Cu > Pb > Cr; the difference between Zn content and Cr content was significant( P < 0. 01); ④ the relationship between heavy metal content in plant leaves and soil heavy metal pollution levels presented a quadratic polynomial relation; the significant correlation was found between other three heavy metal contents of plant samples and soil samples,but they were not the case for the Cu,and the correlation coefficients were above 0. 9.