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

Abstract

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 Eri values, Cd and As were the most ecologically harmful elements. The study area was at a medium risk level.