小秦岭典型地段植物重金属污染特征分析

Study on the impact of heavy metal pollution on vegetables and fruits in a typical section of Xiaoqinling

在研究区采集了132组植物样品,并对样品中As、Hg、Cu、Zn、Pb、Cd、Cr、Ni 8种重金属含量进行了测试,采用环境指数作为植物重金属污染评价方法来描述受污染程度,得出了不同种类植物的重金属污染状况。通过对比分析富集系数,研究了重金属在植物中的富集特征。其研究结果表明:不同植物中重金属含量超标倍数和吸收量明显不同,显示出选择性富集特征。该次采集的所有植物中As、Hg的含量都不超标;红薯中Cd和Pb的含量超标倍数最高,玉米中Zn的含量超标倍数最高,Cu也比较容易在粮食作物中累积且以红薯最为突出;蔬菜中Pb、Cd、Zn的含量超标倍数最高,以白萝卜、白菜最为突出;水果中Pb的含量超标倍数最高,且苹果和柿子都较为突出。该次采集的植物对Pb的吸收能力都很强,只有玉米对Zn的吸收能力比其对Pb的吸收能力略强。受到重金属污染的土壤所种植的粮食、蔬菜和水果均有不同程度的富集,其对重金属吸收强弱的排序分别为:白菜、白萝卜和胡萝卜中,Pb>Zn>Cu>Ni>Cr>Cd>Hg>As;红薯和茄子中,Pb>Cu>Zn>Ni>Cr>Hg>Cd>As;南瓜和苹果中,Pb>Cu>Zn>Ni>Cr>Hg>As>Cd;柿子中,Pb>Ni>Cu>Zn>Cr>Hg>As>Cd;玉米中,Zn>Pb>Cu>Ni>Cr>Hg>As>Cd;西红柿中,Pb>Zn>Cu>Ni>Cr>As>Cd>Hg。

132 groups of plant samples are collected,and the content of 8 heavy metals—As,Hg,Cu,Zn,Pb,Cd,Cr and Ni. Environmental index is used as evaluation indicator of plant heavy metal contamination describing the contamination degree and the contamination situations of different plants are obtained. Based on the comparison and analysis of Enrichment Coefficient,the paper studies the enrichment characteristics of heavy metal in plant. The research results show that the overabundance degree and absorption amount of heavy metals in different plants vary significantly showing the characteristic of selective enrichment. For the plants collected this time,the content of As and Hg are both under control; the overabundance degree of Cd and Pb in sweet potatoes is the highest while Zn overabundance in corns is the highest; Cu is also likely to accumulate in crops,especially in sweet potatoes; Pb,Cd and Zn overabundance is the most prominent in vegetables,especially in white radish and Chinese cabbage samples; as for fruits,Pb overabundance is the highest,especially in apple and persimmon samples. The sampled plants show good absorbing capability of Pb,except that Zn can be absorbed more easily than Pb in corn samples. The grains,vegetables and fruits planted in heavy-metal-polluted soil all have enrichment of different level. The capability of absorbing heavy metals can be sorted as follows： Pb Zn Cu Ni Cr Cd Hg As in Chinese cabbage,white radish and carrot samples;Pb Cu Zn Ni Cr Hg Cd As in sweet potato and eggplant samples; Pb Cu Zn Ni Cr Hg As Cd in pumpkin and apple samples; Pb Ni Cu Zn Cr Hg As Cd in persimmon samples; Zn Pb Cu Ni Cr Hg As Cd in corn samples; Pb Zn Cu Ni Cr As Cd Hg in tomato samples.