Reasonable sampling density for land parcel scale geochemical assessment on land quality in Northeast China Plain
Min PENG1,2,3,4, Kuo LI1,2,3,4, Fei LIU2,3,4, Shi-Qi TANG2,3,4, Hong-Hong MA2,3,4, Ke YANG2,3,4, Zheng YANG2,3,4, Fei GUO2,3,4, Hang-Xin CHENG2,3,4
1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China 2. Institute of Geophysical & Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang 065000, China; 3. Research Center of Geochemical Survey and Assessment on Land Quality, China Geological Survey, Langfang 065000, China 4. Key Laboratory of Geochemical Cycling of Carbon and Mercury in the Earth’s Critical Zone, Chinese Academy of Geological Sciences, Langfang 065000, China.;
In order to identify the reasonable sampling density for land parcel scale geochemical assessment on land quality in Northeast China Plain, the authors studied spatial variability of elements in soils as well as reasonable sampling size based on classic statistics and conducted a thorough comparison of interpolation accuracies at four sampling densities in a typical area in Gongzhuling City of Jilin Province. As the area is dominated by flat land and the soils parent materials are mainly homogeneous sediments, most of elements in soils in this area display a minor to moderate variability, Cd and Hg which are sensitive to human activities have a significant higher coefficient of variation of 35.3% and 136.6%, respectively. Classic statistics show that sampling size of 80 is sufficient for providing a reliable estimation of mean and variance for the elements concentration in soils in this area ( under a P value of 95% and Er tolerance level of 30%); however, classical statistics could not make out the spatial allocation of soil properties at the unsampled locations. By comparing the relative error of spatial interpolation, the predicted value for land parcel and the predicted classes at four sampling densities, the authors suggest that the reasonable sampling density is 8 samples per square kilometer for land parcel scale geochemical assessment on land quality in the study area and similar areas in the Northeast China Plain, considering the tolerance level of Er (relative error) for the geochemical assessment on land quality. The results obtained by the authors may help optimize soil sampling density in land parcel scale geochemical assessment.
彭敏, 李括, 刘飞, 唐世琪, 马宏宏, 杨柯, 杨峥, 郭飞, 成杭新. 东北平原区地块尺度土地质量地球化学评价合理采样密度研究[J]. 物探与化探, 2019, 43(2): 338-350.
Min PENG, Kuo LI, Fei LIU, Shi-Qi TANG, Hong-Hong MA, Ke YANG, Zheng YANG, Fei GUO, Hang-Xin CHENG. Reasonable sampling density for land parcel scale geochemical assessment on land quality in Northeast China Plain. Geophysical and Geochemical Exploration, 2019, 43(2): 338-350.
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