POLLUTION EVALUATION AND SOURCE ANALYSIS OF HEAVY METALS IN THE URBAN-RURAL FRINGE: A CASE STUDY OF LANZHOU CITY GANSU PROVINCE CHINA

To study the pollution characteristics and sources of heavy metals in the soil near an urban- rural junction in an industrial area, this research analyzes the soil in the urban-rural junction of an industrial zone in Xigu District, Lanzhou City, Gansu Province. An X-ray fluorescence spectrometer is used to determine the content of 11 elements, namely, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Hg, Pb, and Fe, in the soil. Pollution evaluation is carried out using geo-accumulation, single-factor pollution, and Nemerow comprehensive pollution indices. The sources of heavy metals are analyzed through correlation analysis, factor analysis, cluster analysis, and other mathematical statistical methods, combined with spatial distribution characteristics. Results show that in the soil of the study area, only the average contents of Co, Zn, Hg, and Pb elements exceed the elemental background value of Gansu soil. The contents of other heavy metals do not exceed the elemental background value of Gansu soil. Mn, Fe, Co, Cr, As, and Ni are mainly affected by natural sources (earth-forming parent material or geological background). Pb, Cu, and Zn are mainly affected by anthropogenic sources (such as human agricultural activities). Cd and Hg are mainly from industrial sources (industrial activities, such as those from the petrochemical industry). The research results can provide a reference for the prevention and control of heavy metal pollution in the study area.