城市土壤的压实退化及其环境效应

The Compaction Degradation of Urban Soil and its Environmental Impacts

城市土壤普遍存在严重的压实退化现象。由于压实的影响,土壤物理性质发生了显著的改变:结构破坏、容重和硬度增大、孔隙度和渗透性降低。这些重要的变化对土壤生物活动、土壤物理-化学平衡和氧化还原状况、土壤的过滤和缓冲性能都产生影响。由此对环境产生严重的负面效应:地下水的自然回灌减少,地表径流量增加,降雨的径流洪峰加快、加大,地表水体的污染负荷增加。土壤温度、微生物活动、养分转化都不同于自然土壤,植物的生长也受到严重的影响。

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.