Abstract:

【Objective】 Studies on the spatial variability and influencing factors of heavy metals can provide useful informations for the protection of environmental quality of cropland. 【Method】 Geostatistics combined with GIS were used for the analysis of the spatial structral, spatial distribution and influencing factors of copper (Cu), zinc (Zn), and chromium (Cr) concentrations in cropland soil in Shuangliu county, Sichuan province, China. 【Result】 The concentrations of Cu, Zn and Cr in cropland soil belonged to moderate variability, the maximum value and minimum value of the three heavy metals were obviously different. The spatially dependent ranges of concentrations of Cu, Zn, and Cr in soil were 28 281, 45 613, and 45 892 m, respectively. The concentrations of Cu, Zn, and Cr in soil had a moderate spatial dependence, and their spatial variability was caused by structural factors and random factors. 【Conclusion】 The ordinary Kriging interpolation showed that the spatial distribution trends of concentrations of Cu, Zn, and Cr in soil were quite similar. The regions with high concentrations of Cu, Zn, and Cr in soil were mainly distributed in the northwet part of Shuangliu. The results of influencing factors showed that the concentration of Cu in cropland soil was very significantly different among different terrain conditions. Soil parental materials was an important factor affecting spatial variability of the concentration of Cu and Zn. The organic fertilizer application rate was the important factor which affected spatial variability of the concentration of Cu, Zn, and Cr in cropland soil. The influence degree of agricultural conditions and fertilizer application rate on spatial variability of the concentrations of Cu, Zn, and Cr in cropland soil was the highest in social economic conditions .

Key words: county scales, cropland soil, copper, zinc, chromium, spatial variability, influencing factors