| This study surveyed soil physical and chemical properties (pH value, organic matter content and soil texture), heavy metal contents (Pb, Cu, Zn), magnetic parameters (Xlf, Xhf, Xfd) of 135 samples which were collected from the roadside soils along Huohou road and based on heavy metal contents and magnetic parameters to investigate distribution of heavy metals. Combine SEM, EDX and correlation of various indicators to reveal the soil heavy metal genesis and source of contamination. Meanwhile, various methods were used for the pollution assessment, and sources of heavy metals in soil samples were also analyzed. The main conclusions are as follows:(1) In study area, the average contents of Pb, Cu, Zn were 74.40 mg/kg,59.60 mg/kg,80.95 mg/kg, separately. The contents of Pb and Cu exceeded background value of soil environments in Shanxi province,61.8 percentage of Zn contents exceeded background value of soil environments in Shanxi province. And the average contents of Pb, Cu, Zn elements had not exceed the national average levels of soil environmental quality standard. From the coefficient of variation, the coefficient of variation of three heavy metals expressed as Zn (36.46%)> Pb (33.97%)> Cu (33.44%), heavy metal elements were within the moderate range of variation. The contents of heavy metals were highest on soil surface and showed a decreasing trend with the deepening of the depth, which indicated that heavy metals in soil may be derived from anthropogenic sources.(2) The correlation of physicochemical properties of soil and heavy metals displayed that soil pH is positive correlated with Pb, Cu and Zn, and had an obviously positive correlation with the content of Pb, which indicated the higher of soil pH, the more enrichment of Pb, Cu, Zn; organic matter and three kinds of heavy metals content were positively correlated, indicating that the higher of soil organic matter content, the more enrichment of these three metals. The correlation of physicochemical properties of soil and heavy metals indicated the metal contents are affected by the physical and chemical properties to some extent.(3) In the study area, the high values of magnetic susceptibility were seen in the distance of 5-15m from road edge, which had a wide range of consistency in space with heavy metals; and in the soil profile, the heavy metal and magnetic susceptibility also showed a similar vertical variation. According to correlation analysis, Xlf were significantly correlated with three metals, and had a significant positive correlation with Pb; Xfd% were negatively correlated with three metals, but the correlation was not significant. The significant correlation between magnetic susceptibility and metals showed the higher of the magnetic susceptibility, the higher of heavy metal contents. At the same time, it showed that magnetic particles and heavy metals have similar sources, settlement and migration process. Magnetic susceptibility can be an useful indicator of accumulation of heavy metals in the soil.(4) In the study, three heavy metals had high coefficients of variation, significant positive correlation with magnetic susceptibility. Furthermore, by scanning electron microscopy and X-ray spectroscopy can identify the traffic pollution magnetic particles. In the absence of other sources of pollution around the plots, so that we can see from the above analysis, the three heavy metal elements were derived from traffic pollution, soil on both sides of the road had been affected by traffic conditions.(5) By calculating the accumulated contribution rate of three heavy metals, geological accumulation index, single pollution index, Nemerow pollution index and potential ecological risk of environmental quality of soil sample to assessment the environment quality of study area. The results showed that the enrichment of Pb was in serious condition, which had caused some harm to the soil environment of the study area, the ecological threats of Cu and Zn were relatively mild, but it should be more adequate attention. |
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