杭州市六种常见绿化树种叶片累积空气重金属特征及与环境因子的相关性

Characteristics of the accumulation of heavy metals in the leaves of six common green tree species and its correlation with environment factors in Hangzhou City, China

关键词:  绿化树种, 重金属, 累积, 降尘, 土壤

Key words:  green trees, heavy metal, accumulation, dust fall, soil

摘要:

该研究选取杭州市2个污染区常见的6种绿化树种叶片作为材料,以清洁区为对照,采用电感耦合等离子体发射光谱法,测定受试树种叶内及对应样点降尘、土壤中Pb、Cd、Cr、Cu、Ni和Zn的含量,分析叶片的吸污能力以及重金属含量与土壤、降尘的相关性。结果表明:(1)污染区树种重金属含量明显高于对照区,绿化树种对环境重金属污染物有一定的吸收能力,重金属含量在不同的树种中具有明显差异; 所测树种叶内Zn含量最大,Pb次之,Cd最小,指示能力则以枸骨(Ilex cornuta)对Cd和Pb、圆柏(Juniperus chinensis)对Cu、茶花(Camellia japonica )对Ni、广玉兰(Magnolia grandiflora)对Zn为最强。(2)3个样点树种叶片与对应样点土壤、降尘中重金属元素含量的相关性分析和回归分析表明,叶片重金属含量与土壤重金属含量的相关性较小,而与降尘呈显著正相关。因此,绿化树种叶片作为空气重金属污染的累积器和监测器是科学合理的,且上述4种树种对杭州市空气中6种重金属污染的指示作用具有一定参考价值,可作为监测城市空气质量的特型树种。该研究结果为减少城市空气重金属污染提供了科学依据和理论支持。

Abstract:

In order to detect the heavy metal accumulation ability and the effects of environmental factors on the green tree species leaves, six common green tree species were selected for analyzing six heavy metal elements(Pb, Cd, Cr, Cu, Ni and Zn)concentrations in samples. Three areas were chosen for this research in Hangzhou, China, two industry areas for heavy metal pollution treatments and one natural area for control. Afterwards, leaf, soil and dust fall samples were collected to test the six heavy metal element concentrations using the element analyzer(ICP-AES). The results were as follows:(1)According to the accumulation factors and correlation indexes, we suggested that heavy metal concentrations in the leaves from pollution areas were obviously higher than those in the control. Generally, Zn accumulated the highest concentration in those plants, followed by Pb, and Cd of the lowest. However, different species had inequable abilities on heavy metal accumulation. We infered that Ilex cornuta could be a bio-monitor on Cd, Pb. Juniperus chinensi, Camellia japonica and Magnolia grandiflora could be indictors on Cu, Ni and Zn, respectively.(2)The correlation and regression factors of the six heavy metal concentrations between three collecting areas and leaf samples showed that the heavy metals absorbed in leaf samples had more positive correlation with dust from atmosphere than that from the soil samples. Therefore, it is reasonable and scientific that these trees could be selected as accumulators and bio-monitors of the atmospheric heavy metal pollution. The results provides important references on the indictors and bio-monitors searching about the atmospheric heavy metal pollution.