The Compaction Degradation of Urban Soil and its Environmental Impacts

The compaction degradation of soil in urban area is universal. The physical characteristics of urban soils change evidently because of the compaction — destruction of soil structure, increase in bulk density and penetration strength, reduction in porosity and infiltration rate. All these changes affect the biological activity, redox conditions, heat balance and the filtering and buffering capacity of soils to contamination. Water and air quality in urban area are also influenced by soil compaction through various mechanisms, e.g., the increase of surface runoff and reduction of surface water infiltration to groundwater. The peak of flooding caused by (storm) rainfall appears earlier and stronger than that under a natural land cover condition. The non-point source pollution with surface water is aggravated by low infiltration and high runoff volume as well as high pollutant load in urban area. Plant growth in urban area is also affected by the special conditions of soil environment.