乡镇级土壤地球化学调查精度探讨——以北京礼贤镇为例

Discussion on the Precision of Soil Geochemical Survey in Township: A Case Study of Lixian Town, Beijing

在研究区以往工作的基础上,采用随机抽稀的方法,将采样密度40件/km2分别抽稀至20件/km^2、10件/km^2、4件/km^2,对比4种采样密度下的数据特征和地球化学图差异性。研究目的是改进现有调查方法,以低密度代替高密度采样,较少的样本量反映较为真实的地球化学特征,以起到节约成本、提高效率的作用。研究结果:数据特征基本不受采样密度的影响;但地球化学图面效果受密度影响大,且40件/km2和20件/km^2的成图效果基本一样,仅存在微小差异。因此,在开展乡镇级地球化学调查时,建议使用20件/km2的调查精度,根据调查成果在靶区内开展高精度、全覆盖的独立地块采样。

On the basis of the previous work in the study area, the sampling density of 40 pieces/km^2 was diluted to 20 pieces/ km^2, 10 pieces/km^2, 4 pieces/km2 by random thinning method, and the data characteristics and geochemical maps under four sampling densities were compared. The purpose of the study is to replace high-density sampling with low density, and less sample size reflects more realistic geochemical characteristics, which saves cost and improves efficiency. The conclusion of the comparative study is that the data characteristics are basically unaffected by the sampling density;the geochemical map’s showing effect is greatly affected by the density, and the map’s showing effect of 40 pieces/km^2 is as basically same as that of 20 pieces/ km^2. Therefore, it is recommended to use a survey accuracy of 20 pieces/km^2 when conducting a township-level geochemical survey. Based on the survey results, independent block sampling with higher precision and full coverage has been performed in the target area.