Influence Of Urbanization On The Soil Quality In Developed Regions

Urbanization is an inevitable trend of development of human society, have become important social and economic phenomena. However, Urbanization is changing lifestyles, but it also has posed enormous amount of challenges to many aspects of environment of cities and its periphery, e.g. resources, ecology, environment, etc. Among them, soil and land resources, the bases of human survivals, are facing unprecedented pressure.Fuyang City, located in the developed Yangtze River Delta region, is an important part of the future metropolis in Hangzhou, has astonishingly prominent issues of soil and land resources, quality, environment, which are brought about by rapid urbanization. In this study, the urban sprawl pattern of Fuyang City from 1996-2009 and its influences on soil resources were analysed, with the database of land use in 1996,2004 and 2009 and the data of soil samples collected in 2006 in Fuyang City; Meanwhile, the research analyzed spatial variability of soil fertility factors and heavy metals by GIS and geostatistics, as a consequence, soil fertility and environmental quality were assessed respectively, with the Soil Fertility Index (IFI) method and the Nemerow Comprehensive Index method; analysis the impacts of different land management policy on soil fertility quality and environmental quality in the process of urbanization; Finally, based on results got from processes above, the impacts of urban expansion on basic farmland and requitision-compensation of arable land have been conducted. The results are as follows:(1) Since 1996, Fuyang City, was to accelerate the development trend of urban expansion, a corresponding amount of resources has also led to the continuous reduction in the soil.Urbanization has been posing impacts on the quality of soil and arable land. To be specific, area of urban land in Fuyang City increased by 3.7 times in the past 13 years. Among them, in the period of 1996-2004, the annual expansion rate of urban land achieved 23.00% astonishingly, and the rate of township expansion doubled that of urban areas; and from 2004 to 2009, urban land expansion rate started to slow down, specifically, the annual expansion rate dropped to 6.03%, and urban areas sprawled faster than township (3.7 times). Space for urban expansion from the point of view, the major expansion of urban areas are located along both sides of Fuchun River, and to Fuyang City as the center and radial expansion of the surrounding cities and towns, while the southwestern Xindeng town and northern Wanshi town sprawled fast as well. In addition,88.15% of urban expansion occupied high quality paddy soil types in Fuyang City from 1996 to 2009, the development of urbanization in Fuyang City has been adverse effects impacted on the soil quality and land quality.(2) Spatial variation of soil fertility and environmental quality characteristics:In the study area, there are obvious spatial variability of soil pH, available P, and available K, especially available P and available K influenced by anthropogenic factors is relatively large. The soil fertility quality in Fuyang City is high as a whole and is full of potential, which comprises mainly soil type III soil, followed by soil typeâ…¡,â…£,â… Type I andâ…¡are mainly distributed in the three major agricultural development zones of Fuyang City, and typeâ…£is distributed sporadically, while type III is of wide distribution. As illustrated in this dissertation, different land use patterns have influenced the soil fertility quality of Fuyang City, which will pose challenges to reasonable configuration and scientific management of soil resources.As far as soil in the study area, in spite of the accumulated heavy metals within it, most of it is not affected. Soil Cu, Ni, Pb and Zn have obvious spatial variability, whereas soil Cd has good spatial correlation. Judging from the evaluation of soil environmental quality, land use is the main factor leading to soil heavy metal pollution in Fuyang City. It is reported that the heavy metal pollution in the region can be ranked from light to heavy as follows:towns, urban, suburban, other land, village, mining lease. Towns and urban areas is relatively better soil environmental quality, without pollution but heavy metal has accumulated in the soil; other regions have been polluted by soil heavy metal due to discharge of industrial waste and long-term application of chemical fertilizers and pesticides.(3) The relationship between the urbanization and basic farmland, requisition-compensation of arable land:After basic farmland adjustment, area of basic farmland in 2009 has increased 76.59hm2 than that of 1996 in Fuyang City, and more focused contiguous layout, soil quality is also improved over 1996, however, the decline of soil environmental quality should be given enough attention.Requisition-compensation of arable land has been achieved in the process of urbanization of Fuyang City in the period of 1996-2009. However, the space from Requisition-compensation of arable land point of view, requisition of farmland mainly distributed in hilly and plain land along Fuchun River and State Highway 320, whereas the compensation of arable land is relatively dispersed, mainly distributed in the mountain and hilly regions in the northwest part of Fuyang City; from the elevation and slope point of view, the quality of cultivated land in Fuyang City has declined, while the upward trend in the slope is not obvious; from soil fertility quality point of view, requisition is mainly constituted of high-grade soil, while low level soil is compensated, the quality of cultivated land has declined; from the soil environmental quality perspective, although the environmental quality of compensational arable land is better than the cultivated land requisitioned, heavy metals has begun enriching in soil of compensational arable land, i.e., soil quality tends to declined.