宝鸡市绿植叶片重金属空间分布及污染特征

绿化植物作为城市灰尘重金属污染物的重要承载体，在反映污染指标和生物富集方面有巨大潜力，对改善城市人居环境质量和城市园林规划具有重要意义.为定量描述宝鸡市城区10种优势绿植叶片重金属污染程度、空间分布及对灰尘的富集特征，采集并测定了宝鸡市区0、1和3m高度上、156个叶片样品中Pb、Zn、Cu、Cr、Ni、Co、Cd和As这8种元素的含量，并计算其生物富集系数（BCF）、污染负荷指数（PLI）与潜在生态风险指数（RI）.结果表明，宝鸡城区绿植叶片中富集最多的元素是Cr、As、Ni、Pb和Cd.沿阶草中Cr、Ni和As含量最高，女贞叶片中的Cd、塔松叶片中的Pb、Ni和As含量较高.BCF结果显示，三叶草、女贞和石楠对Cd有显著富集能力.在空间分布上，Cr、As、Ni、Pb、Cd和Zn元素含量均随高度增加而递减，其中Cr元素递减率达24%，千河工业园、任家湾火车站及市政府周围为含量峰值区，PLI在任家湾火车站、千河工业区出现中度污染，RI值在这两区域为中度生态风险等级，同时在高新大道沿线达到较强生态风险等级.在绿植叶片中，Cr和As的PLI值都>3，均达到重度污染水平.E_rⁱ的平均值大小顺序为：As > Cd > Cr > Ni > Pb > Co > Zn > Cu，Cd和As是最具生态危害的元素.8种重金属的综合潜在生态风险指数RI范围为10.58~2982.72，样点中有18.59%的RI值高于150，表明研究区总体上处于中等风险等级.本研究结果对工业城市重金属污染治理及绿植遴选具有一定的理论和实践参考价值.

Spatial Distribution and Pollution Characteristics of Heavy Metals in Plant Leaves in Baoji City

As an important carrier of heavy metal pollutants in urban dust, green plants play an important role in the study of heavy metal pollution in the environment. To quantitatively assess the pollution degree, spatial distribution, and characteristics of dust accumulation of heavy metals in the leaves of 10 dominant green plants in Baoji City, the contents of Pb, Zn, Cu, Cr, Ni, Co, Cd, and As were determined in 156 leaf samples with a ground height of 0, 1, and 3 m in Baoji City, and the biological enrichment coefficient (BCF), pollution load index (PLI), and potential ecological risk index (RI) were calculated. The enrichment amounts of Cr, As, Ni, Pb, and Cd were the highest in the leaves of the green plants in Baoji City. The contents of Cr, Ni, and As in Ophiopogon Japonicus were the highest; the highest content of Cd was found in privet leaves, and the contents of Pb, Ni, and As in the leaves of tarasone were the highest. Clover, privet, and photinia revealed significant enrichment of Cd. The contents of Cr, As, Ni, Pb, Cd, and Zn decreased with an increase in the height of spatial distribution. Moreover, the rate of decrease in Cr was up to 24%, and the peak areas were around the Qianhe industrial zone, Renjiawan railway station, and the municipal government. According to PLI and RI values, the Renjiavan railway station and Qianhe industrial zone were moderately polluted areas with moderate ecological risk level, whereas the high-tech avenue area represented a strong ecological risk level. In addition, the PLI values of both Cr and As in the leaves of the green plants were greater than 3, indicating a level of severe pollution. Based on the average E_rⁱ values, Cd and As were the most ecologically harmful elements. The study area was at a medium risk level.