中国部分大中城市居住区园林土壤碱化现状及主要成因

由于受到剧烈地人为活动的影响，城市园林土壤具有碱化的趋势。为了评价中国园林土壤的碱化现状、验证土壤碱化的原因，对中国不同区域的12个大中型城市的60个住宅项目进行调查取样，并设置了排水处理（+P）、混凝土处理（+C）、排水+混凝土处理（+PC）和对照（CK）4个处理的控制试验。结果表明:1）中国园林绿化土壤普遍存在碱化的现象，12个城市的平均土壤pH达到8.03。2）经过12个月的控制试验后，不同处理的土壤的pH值均提高。4个处理pH值的排序为+C（7.44±0.16）＞+PC（6.73±0.03）＞CK（6.28±0.18）＞+P（5.69±0.08）（土壤本底的pH值为4.98±0.26）。基于以上结果探讨了园林土壤的不透水性和建筑垃圾的混入提高土壤的pH值的机理，并提出了相应的应对措施。通过增加土壤透水性和预防建筑垃圾的掺入等人工措施可以有效地减缓土壤的碱化。

The Present Situation and Main Causes of Garden Soil Alkalization in Residential Area of Large and Medium-sized Cities of China

Due to the heavy influence of human activities,soils in urban residencial gardens present the tendency of alkalization.With the aim of evaluating the current situation of garden soil alkalization in China and finding out the main causes of soil alkalization,this study was conducted on 60 residential districts from 12 large- or medium-sized cities across China,with a combination of field surveys and control experiments.The experimental treatments included concrete addition (+C),concrete addition and permeation (+PC),permeation (+P),and no permeation (control).Results from field surveys indicated that the alkalization of garden soils existed in majority of the residencial gardens investigated.The average pH of garden soils across the 12 cities was 8.03.Results from the 12-month controlled experiment showed that the pH of soils increased from 4.98±0.26 (baseline) to 7.44±0.16 (with concrete addition),6.73±0.03 (with both concrete addition and permeation),6.28±0.18 (with no permeation),and 5.69±0.08 (with permeation),respectively,indicating that concrete addition and no permeation might cause garden soil alkalization.The results showed that effective artificial measures,such as increasing the soil permeability and prevention of construction waste mixed,could effectively mitigate the alkalization of garden soils.