Distribution and attribute analysis of soil selenium in Hebei Province, China

From 2004 to 2018, approximately 73% of the land area in Hebei province was surveyed by a 1:250,000 land quality geochemical survey of the National Geochemistry Survey of Land Quality project (NGSLQ). Based on the topsoil (0-20 cm) datasets (50724 analysis samples) and attribute analysis of the key area with a semivariance function model, geographic detector model and random forest model, the content and spatial distribution of soil selenium (Se) in Hebei province and the influencing factors of the distribution of Se in the Shijiazhuang-Xingtai-Handan area were obtained. The soil Se content in Hebei Province is low, ranging from 0.02 to 3.23 mg/kg, with an average of 0.20 mg/kg. The spatial distribution of soil Se was heterogeneous, and the marginal Se (0.125-0.175mg/kg) area and the sufficient Se (0.175-0.40 mg/kg) area were widely distributed, but the acreage of the Se-rich (0.40-3.0 mg/kg) area was very limited, accounting for only 2.43% of the total survey area. However, the Shijiazhuang-Xingtai-Handan area was a significant Se enrichment area. The spatial distribution of Se in the Shijiazhuang-Xingtai-Handan area was restricted by natural factors and socioeconomic factors. Soil organic matter (SOM) was the most influential factor and showed good coordination with Se. Coal burning superimposed on natural factors promotes the spatial differentiation of soil Se to a certain extent.