Distribution Pattern and Influencing Factors of Soil Selenium in Northern Hebei Province, China

According to the 1 : 50000 scale soil geochemical survey from a several of key selenium (Se) rich areas in the traditional considered Se deficiency area of northern Hebei Province, China, the content, distribution, and the influencing factors of surface soil Se distribution in this area were determined. The Se concentration of surface soil in this area was calculated to be 0.06-3.74 mg/kg, with a mean of 0.4 mg/kg. The Se-rich (Se >= 0.4 mg/kg) domains are about 116.8 km(2), accounting for 29.05% of the total areas. The concentration of Se in surface soils tends to decrease in the north and increase in the south. The soil Se content and distribution were affected by various factors. Soil parent rocks were the initial sources of Se, but their effects on soil Se content and distribution were limited. The Se content in surface soil had a strong positive correlation with organic carbon (C-org), S, and Fe2O3, but a weak correlation with topographic parameters. The Se content of various soil types, including meadow chestnut soil, calcareous meadow soil, gley meadow soil, and saline meadow soil, and land use types, including natural grassland and other grassland, were relatively high, mainly because of the indirect effect from abundant organic matter and high water content in soil. Additionally, the analysis result of GeoDetector showed that S and C-org were the main driving factors of soil Se distribution and the influence of other factors was limited.