杭州市城乡结合带蔬菜地土壤铅铜含量的时空变异研究

SPATIAL-TEMPORAL VARIABILITY OF LEAD AND COPPER CONTENTS IN VEGETABLE SOIL IN THE PERI-URBAN AREA OF HANGZHOU CITY

土壤重金属时空变异研究在土壤可持续利用和生态环境保护过程中具有重要的意义。通过2001年和2005年两个时期在杭州市东郊传统蔬菜基地取样分析,用空间自相关全局Moran’s I系数、地统计学以及分形维数三种空间分析方法研究了土壤重金属Pb和Cu的时空变异特征。两个时期的Pb和Cu平均含量分别由38.73、31.20 mg kg-1增加至46.14、36.56 mg kg-1,并经检验,Pb和Cu含量增加达到了显著水平。它们在0.05显著水平的自相关距分别由3 500 m、3 300 m降低至2 700 m、2 800 m,呈递减趋势,空间随机性增强。土壤Pb和Cu的空间分布呈西高东低,并且在研究区绝大部分范围内出现不同程度的累积趋势。人为污染与干扰是土壤Pb和Cu含量增加与空间变异性增强的主要原因。

The study on spatio-temporal variation of soil heavy metals is of important significance in sustainable utilization of the soil and protection of the coo-environment. Soil samples were collected from vegetable fields （0 - 20 cm） in the prei-urban areas of Hangzhou City, 43 in 2001 and 74 in 2005, determined for total Pb and total Cu, and analyzed with the Moran＇ s Ⅰ, Geostatistics and the Fractal methods for their spatio-temporal variation of soil heavy metals. Results show that the mean content of soil Pb and Cu increased form 38.73 mg kg^-1 and 31.20 mg kg^-1 in 2001 to 46. 14 mg kg^-1 and 36.56 mg kg^-1 in 2005, respectively, demonstrating a significant increase. The autocorrelated distance of soil Pb and Cu at the 0. 05 significance level decreased from 3 500 m to 2 700 m and from 3 300 m to 2 800 m, respectively, showing a decreasing trend in spatial distribution of soil Pb and Cu from west to east across the study area. The accumulation of soil heavy metals might be attributed to intensified human activities.