Analysis of Heavy Metal Pollution and Ecological Risk Assessment on Vegetation Leaves in Baoji City

Abstract

Using seven types of vegetation and seven heavy metals (Cr, Cu, Ni, Mn, Pb, Cd, and As), the present study explored the ability of accumulation and degree of contamination in the leaves of vegetation in Binhe Road. The results demonstrated a negative trend between vegetation height and heavy metal content of vegetation leaves, i.e., as plant height increased, heavy metal contamination decreased. Leaves varied in the accumulation of heavy metals depending on the heavy metal and vegetation type. Cr, Mn, and Pb content were the most abundant in vegetation leaves. The highest values for Cr, Cu, Ni, and Mn were observed in the vegetative leaves of Hybrida vicary privet and were 217.33, 58.61, 36.79, 1676.14 mg·kg-1, respectively. The highest Pb content was 1295.64 mg·kg-1 in Ligustrun lucidum, the highest Cd content was 110.19 mg·kg-1 in Cedrus deodara, and the highest As content was 139.42 mg·kg-1in Prunus cerasifera. The degree of pollution in vegetation leaves was evaluated using the comprehensive index method Single-factor pollution index method and the Nemero Composite Index Method. The Single-factor pollution index of vegetation leaves with Prunus cerasifera, Platanus acerifolia, Cercis chinensis were between 0.02-1.23, and the Nemero Composite Index values were 1.01, 0.82, 0.4, respectively, with light pollution. The Single-factor pollution index of vegetation leaves by Cedrus deodara, Platycladus orientalis, Hybrida vicary privet and Ligustrun lucidum were much higher than 1, and the Nemero Composite Index was 16.53, 140.64, 98.80, and 37.52, respectively, with high levels of pollution. The potential ecological risk of heavy metals in vegetation leaves was determined using the Hakanson potential ecological risk assessment method. The order of the average potential ecological risk degree of the seven examined heavy metals was as follows:Cd > Ni > Cr > As > Pb > Cu > Mn, and the RI value range was 19.04-4020.29, with high levels of pollution.