上海市城乡梯度上土壤铅的空间分布特征及其景观变量解释

如何量化城市中土壤Pb的空间分布是城市土壤P研究的热点问题之一。本文以景观格局指数、人口和经济指标、交通流量和道路密度等为变量,采用景观变量空间插值、滑动窗口分析以及线性回归分析等方法定量解析沿城市化梯度上土壤Pb的分布。结果表明,土壤Pb不仅受交通流量的影响,也与景观格局指数所反映的城市化过程有关。逐步线性回归模型显示,景观形状指数(LSI)和道路密度(RD)可以解释69%土壤铅的空间变化,景观形状指数(LSI)和道路密度(RD)所占的百分比分别为56%、13%。说明景观破碎度、复杂性越高,道路密度越高,土壤Pb的浓度值越高。研究证明梯度分析法和景观格局指数相结合的方法可以有效解释城市化扩张的异质性格局及其环境效应。

Quantifying soil lead distribution by landscape variables on an urbanization gradient in Shanghai, China

How to quantify the spatial distribution of soil Pb in urban area is a pending question for urban soil Pb research. In this study, along with an urban-rural gradient, variables of landscape metrics, demographic and economic attributes, traffic volumes, and road density are included to model the soil Pb distribution. Methods of soil Pb and landscape variables spatial interpolation, moving windows zonal statistics, and linear regression analysis are used to quantify the soil Pb distribution. Results show that Pb is not only affected by traffic, but also by the urbanizing rate. The stepwise linear regression model reveals that landscape shape index (LSI) and road density (RD) could account for 69% of soil Pb spatial variation, in which the accounted percentage of LSI, and RD are 56% and 13% separately. This indicates that more fragmented and more complexity of the landscape, the higher the road density, and then the higher the Pb value. Our research demonstrates that the gradient analysis is workable to illustrate the spatial heterogeneity of urbanization and the associated soil Pb distribution.