郑州市典型城市土壤剖面Zn、Ni分布特征分析

为探讨城市土壤重金属的分布、成因及迁移特征,选取郑州市不同功能区土壤9个典型剖面,2个城郊对照剖面,对Zn、Ni含量及其剖面分布进行分析.结果表明:郑州市城市土壤Zn含量与城郊对照土壤存在显著差异;城市土壤Zn含量变幅为17.05～1 400.72 mg/kg,空间变异非常大,平均值为306.67 mg/kg,高于土壤环境质量Ⅱ级标准,存在一定程度的Zn污染;城市土壤Ni含量变幅为6.70～22.33 mg/kg,平均值为12.41 mg/kg,均低于土壤背景含量,不存在Ni污染.城市土壤Zn、Ni含量的剖面分布比较复杂;土壤Zn的剖面分布与居民生活、工业以及交通等人类活动关系密切,具有在表层和亚表层累积的特点;土壤Ni含量大小主要受成土母质影响,垂直分布及迁移主要受城市人类活动扰动的制约而无一定规律.土壤中Zn含量与土壤理化性质不存在相关关系,而Ni含量与土壤粘粒、阳离子交换量等具有显著的正相关关系.

Analysis on Distribution of Zn and Ni in Typical Urban Soil Profiles of Zhengzhou City

In order to investigate the distribution of heavy metals in urban soils,causes and characteristics of migration,nine typical urban soil profiles from different functional areas and two suburban control sections of Zhengzhou City were taken through dividing urban functional area.Contents of Zn and Ni and their profile distributions were analyzed.The results indicate that the contents of Zn in Zhengzhou urban soils are significantly different from those of the suburb.Zn contents ranging from 17.05 mg/kg to 1400.72 mg/kg in urban profile soils indicate a very large spatial variability in the investigated areas,and average of 306.67 mg/kg,higher than grade Ⅱ soil environmental quality standards,so there is a certain degree of Zn contamination.Otherwise,the average of Ni content in urban profile soils is 12.41 mg/kg,lowering than the soil background levels,which means there is no Ni pollution.The profile distributions of Zn and Ni in urban soils are very complex.Zn concentration in urban soil profile,accumulating chiefly on topsoil and subsoil,is strongly related to residential daily lives,industrial activities and traffic transportation.The size of Ni content in the soils is affected by soil parent material,and the vertical distribution and migration hasn’t a regular pattern,because it is mainly constrained by disturbance of human activities.Zn content in soils is no correlation between physical and chemical properties;otherwise,there is a significant positive correlation between Ni content and soil clay,cation exchange capacity.