Abstract:

【Objective】 Studies on the spatial distribution and sampling numbers of the concentration of copper (Cu) on county scale were made to provide a help for the investigation of environmental quality of cropland soil. 【Method】 In this study, Cokriging was used for the interpolation of the concentration of Cu in cropland soil in Shuangliu county in Sichuan province. A total of original 623 measured data of the concentration of Cu in soil and 560, 498, 432 measured data by random were selected as target variable, original 623 measured data of soil organic matter (OM) content as auxiliary variable. The interpolation methods using Cokriging under different sampling numbers were evaluated for the suitability of estimating the spatial distribution of the concentration of Cu in soil on county scale. 【Result】 Compared with the ordinary Kriging under the same sampling numbers, the root-mean-square error produced by Cokriging decreased by 0.9% to 7.77%, correlation coefficient between the predicted value and the measured value increased by 1.76% to 9.76%. The prediction accuracy of original data reduced by 10% using Cokriging was still higher than original 623 data using ordinary Kriging and their interpolation maps were quite similar. 【Conclusion】 Cokriging was shown to be more accurate and economic method which could provide more information and help for the study on the spatial distribution of the concentration of Cu in soil on county scale.

Key words: cropland soil , county scale, copper, Cokriging, sampling numbers