贵州独山县土壤Se元素地球化学特征及其影响因素研究

通过对贵州省独山县表层土壤、土壤剖面、农作物样品的研究，对土壤理化性质、微量元素、土壤-农作物硒含量进行测试分析，研究土壤-农作物硒含量分布特征及其影响因素。研究结果表明：（1）独山县表层土壤中Se元素含量范围为（0.07~5.42）×10-6，均值为0.45×10-6，高于我国土壤背景值和贵州省土壤背景值；西红柿样品中Se含量范围为（0.009~0.017）×10-6，为富硒农产品；土壤总体偏酸性；SOM、N、K2O、B含量均值分别为0.34×10-6、2.04×10-3、11.03%、89.32×10-6，K2O、B含量超过中国土壤A层背景值；N、P、SOM含量高；土壤养分条件优良，有利于富硒农作物的种植。（2）研究区共有富硒耕地 20205.80 公顷， 占全县耕地面积的 50.03%；独山县的富硒耕地大多分布于中北部，南部较少，各乡镇富硒耕地比例最高的是麻万镇和影山镇，分别为 70.96%、70.03%。（3）研究区成土母岩类型Se含量均值白云岩>灰岩>砂岩>粘土岩；土壤类型Se含量均值为水稻土>黄壤土>石灰土；土壤剖面、成土母岩呈现出从深部到表层富集特征；成土母岩样品中Se元素含量为（0.03~0.21）×10-6，泥盆系中统鸡窝寨组、石炭系上统黄龙组和二叠系中统茅口组Se较为富集；这表明富硒农产品、富硒土壤、母质层和富硒岩石密切相关。

Geochemical characteristics and influencing factors of soil Se elements in Dushan County of Guizhou Province

This work analyzed the topsoil, soil profiles and crop samples in Dushan County of Guizhou Province, and tested the soil physical and chemical properties, trace elements and soil-crop selenium content in order to discuss the distribution and influencing factors of soil-crop selenium content in Dushan County. Results show that: (1) The content of Se in topsoil of Dushan County ranges from 0.07×10-6 to 5.42×10-6, with an average value of 0.45×10-6, which is higher than the background value of soil in Guizhou Province and in China. The Se content of tomato samples varies between 0.009×10-6 and 0.017×10-6, indicating that the tomatoes are selenium-rich agricultural products. The soil is generally acidic. The content of SOM, N, K2O and B is 0.34×10-3, 2.04×10-3, 11.03% and 89.32×10-6, respectively, while the content of K2O and B is higher than the background values of soil A layer in China. And the content of N, P and SOM is high. The soil nutrient condition is good for the planting of Se-rich crops. (2) The study area contains 20205.80 hectares of selenium-rich cultivated land, accounting for 50.03% of the total county. Most selenium-rich cultivated land is distributed in the central and northern parts, with little in the south of Dushan County. Mawan Town and Yingshan Town have the highest proportion of Se-rich cultivated land in each township, which is 70.96% and 70.03%, respectively. (3) The average Se content of parent rocks in the study area is dolomite > limestone > sandstone > claystone, while the average Se content of soil types is paddy soil > yellow loam > lime soil. It shows enrichment characteristics from deep to surface in soil profiles and parent rock. The content of Se in the parent rock samples is (0.03~0.21)×10-6, and Se is more enriched in the Middle Devonian Jiwozhai Formation, Upper Carboniferous Huanglong Formation and Middle Permian Maokou Formation. It is indicated that Se-rich agricultural products, Se-rich soil, parent material layer and Se-rich rock are closely related.