乌鲁木齐河滩快速路绿化树种不同器官重金属含量的比较

Comparison of Heavy Metal Contents in Different Organs of Greening Tree Species on the Hetan Expressway in Urumqi

探究园林植物不同器官对重金属富集能力的差异,为城市绿化植物选配提供科学依据。以乌鲁木齐市河滩快速路绿化带为对象,利用电感耦合等离子体发射光谱仪(ICP-OES)对5种常见绿化树种(海棠、山楂、丁香、白榆、大叶白蜡)叶片、树枝和树皮中Cr、Cu、Zn、Ni、Pb、Mn含量进行测定,对比分析5种植物不同器官的重金属富集能力,解析不同器官重金属元素含量(文中提到的含量为质量分数)的相关关系。结果表明,5种绿化树种不同器官对6种重金属的富集能力有显著差异。在叶片尺度上,山楂的富集能力最强,对Cu、Cr、Ni、Zn、Mn元素的富集含量高于其他树种;海棠叶片对Pb元素富集能力相对较强。在树枝尺度上,山楂和白榆的重金属富集含量较高,而丁香和海棠的富集含量较低。在树皮尺度上,丁香的重金属含量高达233.861 mg·kg^(-1),其中Mn和Zn的比重较大,分别占47%和29%。各器官相关性分析可知,叶片与树枝重金属含量呈极显著相关,相关系数为0.444;树枝与树皮重金属含量呈极显著相关性,相关系数为0.572。各器官6种不同重金属含量的相关性分析得知,叶片中Cu与Cr、Ni、Zn和Mn呈显著正相关,与Pb呈负相关(-0.101);树枝中Cu和Mn呈显著正相关(0.891);树皮中Cu与Cr呈负相关性,相关系数为-0.406。通过隶属函数法分析可知,山楂的重金属富集能力最强,海棠的最差。通过3个器官的重金属含量比较发现,叶片的重金属富集能力优于树枝和树皮,3种器官重金属富集含量由大到小排序为:叶片、树皮、树枝。以5种绿化树木重金属富集能力看,将山楂和丁香可作为乌鲁木齐道路绿化中优选并推广的园林植物。

Heavy metals are one of the most common pollutants in the urban ecosystems,they can be easily accumulated in roadside vegetations and soils.Different greening tree species present different enrichment capacities of heavy metals,however,plant pruning management may affect absorption ability of the vegetation.Therefore,to provide scientific basis for the selection of urban greening plants,it is necessary to analyze the differences of heavy metal absorption ability of plant organs.Taking the greening belt of Urumqi Hetan Expressway as the research object,the contents of the metals(Cr,Cu,Zn,Ni,Pb and Mn)in the plant leaves,twigs and barks of five common tree species(Malus spectabilis,Crataegus pinnatifida,Syringa oblata,Ulmus pumila,Fraxinus rhynchophylla)were measured by using optical emission spectrometer(ICP-OES).The correlation between six heavy metal contents in different organs were analyzed to reveal the correlation of different organs.It was found that the heavy metal contents in different organs of 5 tree species were significantly different.In the plant leaves,C.pinnatifida demonstrated the strongest enrichment capacity to heavy metals,especially to Cu,Cr,Ni,Zn,and Mn.The leaves of M.spectabilis had relatively strong ability to absorb Pb.In twigs,C.pinnatifida and U.pumila were found to contain higher amount of heavy metals content,while the enrichment ability of S.oblata and M.spectabilis was weak.In the barks,the heavy metal content of S.oblata was up to 233.861 mg·kg^(-1),among which Mn and Zn account for 47%and 29%,respectively.The correlation analysis showed that the heavy metal content in the leaves was significantly correlated with twigs,the coefficient was 0.444.The content of heavy metal in twigs was significantly correlated with bark,with a correlation coefficient of 0.572.In the leaves,Cu was significantly and positively correlated with Cr,Ni,Zn and Mn,and negatively correlated with Pb(-0.101).In trigs,there was significant correlation between Cu and Mn,with the correlation coefficient of 0.891.In barks,Cu was negatively correlated with Cr(-0.406).A Membership function analysis showed that C.pinnatifida had the strongest enrichment ability to heavy metals,while M.spectabilis had the weakest enrichment ability.The order of heavy metal accumulation ability of three organs was leaf>bark>twig.Based on the heavy metal absorption ability of the five trees,C.pinnatifida and S.oblata can be used as preferred plants for roadside greening in Urumqi.