深圳市典型建筑渣土填海区绿地土壤理化特征研究

Study on Soil Constraining Factors of Green Space in Typical Reclamation Area of Shenzhen City

由于深圳市填海区土壤没有经过原位自然成土及生物演替过程,加上受经济发展和城市化进程的影响,导致绿地土壤质量下降,理化性质发生改变,因此开展填海区绿地土壤研究对于改善该区域生态环境具有重要意义。为明确该区域生态建设的主要障碍因子,于2018年在深圳前海自贸区采集20个土壤剖面(75个样品),采用物理和化学分析方法,测定了其土壤水分、盐分和养分的分布特征。结果表明:土壤含水量、盐分参数和养分含量在土层间的差异均未达到显著水平(P>0.05),在垂直剖面上的分布较为稳定。土壤容重随着土层深度的增加先上升后下降,以30~60cm土层最高,而含水量的变化趋势相反,其随着土层深度的增加先降低后升高,以120~150cm最高,呈底聚型分布。土壤电导率和Na^(+)随着土层深度的增加先上升后下降,在60~90cm达到峰值,分别为其余土层的1.32~2.42倍、1.13~2.75倍,全盐量、Cl^(-)和SO_(4)^(2-)则呈现“降-升-降”的趋势,且电导率、全盐量与Na^(+)、Cl^(-)和SO_(4)^(2-)间均存在极显著相关关系(P<0.01。)此外,各层土壤的p H值为7.57~8.04,且从表层到底层依次递增。根据土壤类型划分标准,该区域1.5 m土体内的土壤均已发生碱化。不同土层的土壤养分差异较大,变异系数在61.2%~101.5%,且有机质贫乏,供氮能力差,有效磷空间变异强度大。填海区绿地土壤存在轻微的盐碱化、养分含量低且空间异质性大,因此利用时应注意降碱和培肥。

Since the soil in reclamation area of Shenzhen has not undergone the process of natural soil formation and biological succession in situ,coupled with the impact of economic development and urbanization,the quality of the green space soil has declined,and the physicochemical properties have changed.Therefore,it is of great significance to study the green space soil in the reclamation area to improve the ecological environment of the region.In order to identify the main constraining factors of ecological construction in this region,20 soil profiles(75 samples)were collected in Shenzhen Qianhai Free Trade Zone in 2018.The distribution characteristics of soil moisture,salinity and nutrients were measured by physical and chemical analysis methods.The results showed that the differences of soil moisture,salinity parameters and nutrient content among soil layers were not significant(P>0.05),and their distribution in the vertical profile was relatively stable.With the increase of soil depth,soil bulk density first increased and then decreased,being the highest in 30~60 cm soil layer,while the change trend of soil moisture was opposite,it first decreased and then increased with the increase of soil depth,and the highest appeared in the subsoil(120~150 cm).Soil electrical conductivity and Na+first increased and then decreased,and reached the peak at 60~90 cm with the increase of soil depth,which were 1.32~2.42 times and 1.13~2.75 times of the rest soil layers,respectively.The total salt content,Cl^(-)and SO_(4)^(2-) showed a"drop-rise-drop"trend,and there were significant correlations between electrical conductivity,salt content and Na^(+),Cl^(-)and SO_(4)^(2-)(P<0.01).In addition,the pH value of each soil layer ranged from 7.57 to 8.04,and increased gradually from the surface layer to the bottom layer.According to the classification standard of soil types,the 1.5 m soil in this area has been alkalized.The variation coefficient of soil nutrients in different soil layers was 61.2%~101.5%.The organic matter content and nitrogen supply capacity were poor,and the spatial variation intensity of available phosphorus was large.In summary,the soil of green space in reclamation area has slight salinization,low nutrient content and large spatial heterogeneity,so alkali should be reduced and soil fertility should be increased.