The Influence of Socio-economic Development on Soil Heavy Metals Accumulation in a Typical Region of Yangtze River Delta

Apply approach of time-space transfer and take soil covered in different years as a carrier, this paper constructed the historical record of soil heavy metals (HMs) content during 1950 to 2006 in Yixing city, an area with rapid socio-economic development in Yangtze River Delta of China, and discussed the impact of socio-economic development on soil HMs content and pollution indexes with gray correlative analysis model. Results are summarized as follows: (1) Variation in Cu, Ni, Pb, and Zn content showed a shape of stretched ¿U¿, which inflexion point is the late 1970s or the early 1980s; The content of As appeared declining, by contrast, there was a notable accumulation of Cd; Co and Cr content showed comparatively stable oscillation. (2) Each index of socio-economy has a high and stable gray correlation degree with soil HMs content. Total population, usage amount of chemical fertilizer and total cultivated area are the three most important impact factors of soil HMs content, conversely, total freight volume, GDP and value of industry output in rural area have the weakest impact on soil HMs content. (3) Soil HMs pollution indexes showed the same trends as temporal variation in Cu, Ni, Pb, and Zn content. Usage amount of chemical fertilizer, total population and total grain yield are the three most important socio-economic factors that contribute to soil HMs pollution, enterprise amount, total cultivated area, gross value of farming, forestry, animal husbandry and fishery product as well as total freight amount have less impact on soil HMs pollution, last and least impact factors are GDP and value of industry output in rural area.