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

[Heavy Metal Pollution Characteristics and Influencing Factors in Baoji Arban Soils].

In order to analyze the sources and factors influencing heavy metal pollution in industrial cities, 62 surface layer (0-20 cm) soil samples were collected in Baoji City for analysis using inductively coupled plasma mass spectrometry (ICP-MS). Cd, As, Cu, Pb, Zn, Cr, Mn, and Ni were detected in the samples. Based on geostatistical methods and geo-detector models, the soil heavy metal pollution load index (PLI) was selected as the best indicator of factors affecting heavy metal pollution. The Unmix 6.0 receptor model was also used to analyze the heavy metal source. The results showed that:① The average concentrations of Cd, Pb, Cu, Zn, As, Cr, Mn, and Ni in the surface soils of Baoji City were 0.77 mg·kg-1, 16.75 mg·kg-1, 40.52 mg·kg-1, 261 mg·kg-1, 17.03 mg·kg-1, 49.18 mg·kg-1, 331 mg·kg-1, and 30.52 mg·kg-1, respectively. These values exceeded the national secondary standard for Cd and Zn, which were 8.2 and 3.8 times more abundant, respectively, than in the background soils of Shaanxi Province, indicating that urban soils are seriously polluted with Cd and Zn. The average concentrations of Cu, As, and Ni also exceeded the background levels; ② The total pollution load index (PLIzone) for heavy metals in the surface soils of Baoji City was 1.36, which indicated mild levels of pollution, as analyzed using a geo-detector. Soil texture and distance to the city's railway had the strongest explanatory power for the distribution of pollutants (PD, H=0.040 and 0.026, respectively, with a combined explanatory power of 0.099); ③ Cd, Cu, and As mainly derive from "artificial sources" associated with industrial and agricultural activities, and Zn and Ni derive from traffic emissions. Cr, Pb, and Mn mainly derive from "mixed sources". Overall, the main source of heavy metals in the surface soils of the study area was classified as "mixed source" and soils were classified as having a mild level of pollution. These results provide scientific support for the prevention and control of heavy metal pollution in the soils of Baoji City.