Multifractal characteristic-based comparison of elements in soils within the Daxing and Yicheng areas of Hefei, Anhui Province, China

Abstract. Industrial and agricultural activities can generate heavy metal pollution that can have a number of negative environmental and health impacts. This means that identifying areas with heavy metal pollution and the sources of these pollutants, especially in urban or developed areas with multiple possible sources of pollution, is an important first step in mitigating the effects of these contaminating but necessary economic activities. Here, we present the results of a heavy metal (Cu, Pb, Zn, Cd, As and Hg) soil geochemical survey and outline a new multifractal characteristic-based comparison method that allows deeper interrogation of soil geochemistry in urban or developed areas. This survey focuses on Hefei, the provincial capital of Anhui Province, China, an area that contains a number of individual towns within a large municipal area. This study focuses on the towns of Daxing and Yicheng both of which are incorporated within Hefei and are are economically focused on industry and agriculture, respectively. Here, we use a multifractal spectral technique to identify differences in the geochemistry of soils within the Daxing and Yicheng areas. The height difference between the two ends of the multifractal spectrum of the geochemical data (Δf(α)) for soils in the Daxing area decreases as follows: Pb > As > Cd > Cu > Zn > Hg, whereas Δf(α) values of the geochemical data for soils in the Yicheng town areas decreases as follows: Hg > Zn > As > Cd > Pb > Cu. These differences indicate that the soils in these areas have differing multifractal geochemical characteristics, suggesting that the differing economic activities in these areas generate distinctly different heavy metal pollutant loads (e.g. Hg dominated agricultural pollution vs. Pb dominated industrial pollution). In addition, all of the elements barring Hg have larger Δf(α) values in the Daxing area compared to the Yicheng area. These larger ranges indicate that the higher concentrations of heavy metals present in soils within the Daxing area (compared to the Yicheng area) are more likely to be related to industrial activities than agriculture. The industrial Daxing area contains significant Pb and As soil contamination, whereas Hg is the main heavy metal present in soils within the Yicheng area, indicating that differing clean-up procedures and approaches to remediating these polluted areas are needed, rather than a single approach to heavy metal pollution. The research presented here also highlights that the soils in these areas (and the source of these pollutants) need to be remedied in order to avoid further health and environmental impacts.