Abstract
The core of urbanization is land use change, resulting in the urban sprawl and urban population explosion. The problem of land resources shortage and ecological environment destruction has become increasingly prominent. Land use change and human activities can directly lead to urban soil pollution. This study analyzed the concentration of Cd, Cr, Cu, Ni, Pb, Zn, Hg and As in the original site of Xi’an chlor-alkali chemical plant, which was know as a brownfield. The results showed the concentrations of Hg, Pb and Zn in research areas were obviously higher than soil background value. Through pollution index (PI) method and Geo-accumulation Index (Igeo) method, totally 26 sample points in different areas (A, B, C, D) were classified into different pollution degrees. The CPI results indicated 9 sample points were heavily polluted, accounting for 34.6% of the total. Among them, 6 out of 9 were located in area A. 12 samples points were not polluted. The average Igeo values of single heavy metal were arranged in the order of Hg (1.83) > Zn (1.26) > Pb (0.33). The pollution of Hg was relatively serious and extensive, especially in area A. It was mainly because of the historical pollution produced by chemical plant. The pollution of Pb in each point was quite different. Mainly influenced by automobile related activities, Igeo(Pb) in sample point 15 and 16 were all beyond 4.00. The average potential ecological risk (PER) of each area was in the order of A (1428) > B (297) > D (249) > C (163). The ecological risk was mainly determined by previous industrial production and present human activity at the same time. People and land are interdependent and interactive. The understanding on the mechanism of man-land interralations, regarding to urban land use and ecological environment, will promote urban sustainability.
Highlights
Urbanization and industrialization are crucial to realize modernization
Through on-site investigation, heavy metal pollution and ecological risk assessment, this study aimed at (1) analyzing the concentration of Cd, Cr, Cu, Ni, Pb, Zn, Hg, As in 26 sample points of research areas; (2) using pollution index (PI) method and Geo-accumulation Index (Igeo) method to evaluate the pollution degree; (3) using Potential Ecological Risk (PER) assessment model to evaluate ecological risk in different areas; (4) specifying the sources of pollution based on the land use pattern and human activities; (5) giving some advices based on man-land interrelations and urban sustainability
Different assessment methods including PI, Igeo, potential ecological risk (PER) indicated the pollution condition between each sample point was quite different in research areas
Summary
Urbanization and industrialization are crucial to realize modernization This process strongly changes the economic structure and ecological system structure of urban areas, and causes a series of ecological environment problems [1,2,3]. The essence of these problems is the deterioration of man-land interrelations. Since 2013, China formally established a new urbanization development strategy of "Human-Oriented" It indicated that the development of urbanization in China had been gradually changed from quantity expansion type to quality promotion type, mainly reflected in the optimization of ecological environment, urban functional layout and industrial structure, as well as the improvement of social security system. Intensification and sustainability of land use became a trend and were widely accepted [9,10]
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