GEOGRAPHICAL RESEARCH ›› 2019, Vol. 38 ›› Issue (2): 414-426.doi: 10.11821/dlyj020171151

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Sources, distribution and ecological risk of soil heavy metals in Guangrao county, Shandong province

Xu ZHOU1(), Jianshu LV1,2()   

  1. 1. College of Geography and Environment, Shandong Normal University, Jinan 250014, China
    2. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China
  • Received:2017-11-27 Revised:2018-08-11 Online:2019-02-20 Published:2019-03-08

Abstract:

A total of 300 samples in topsoils (0-20 cm) of Guangrao county, Shandong province were collected, and each sample was analyzed for As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, and Zn. The sources and spatial distribution of heavy metals were examined using multivariate analysis and geostatistics, and the ecological risk of heavy metals in soils was evaluated using H?kanson's method. The average contents of Co and Pb were lower than the background values of Shandong, and the average concentrations of the other heavy metals were higher than the background values of the province. In particular, the mean contents of Cd and Hg were 1.86 and 2.50 times their respective background values, indicating that there were obvious accumulations of Cd and Hg in surface soils. As, Co, Cr, Cu, Mn, Ni, and Zn mainly came from natural sources, and were controlled by parent materials. Hg originated from coal combustion and industrial emissions, and was greatly controlled by human activities. Cd and Pb were affected by both natural and human factors. Agricultural practices, especially the application of chemical fertilizers, contributed to the increased Cd contents, while the vehicles emissions were the main human inputs to the Pb contents. The spatial distributions of As, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn were controlled by parent materials with the higher contents in the soils from lacustrine deposit and the Yellow River alluvium; there were significant differences among various land use types, and higher contents were observed around the urban area. Totally, the study area suffered the moderate ecological risk with the high value area corresponding to the urban area; the intense human activities have led to high ecological risk in the urban area. The level of ecological risk was the lowest in the northeast part, the high ecological risk was concentrated in the urban area and the surrounding area, and the other regions had middle ecological risk. Hg was at the considerable ecological risk level, and Cd was at the moderate ecological risk level, while other heavy metal elements were at the low ecological risk level.

Key words: heavy metals, sources, spatial distribution, ecological risk, Guangrao county