Environmental Geochemical Characteristics of Selenium in Northeastern China

Abstract Keshan Disease (KD) is still a serious endemic public health problem in Northeast China. Previous studies have mainly focused on soil selenium content, staple food selenium content, and human selenium level, but there are few systematic studies on soil selenium existing forms and their migration from soil to crops and human body. In order to provide visualization of the spatial distribution characteristics and migration status of soil selenium content, and to provide a reference basis for the etiological analysis, prevention, control and elimination of KD, the 121183 topsoil soil (0-20 cm) geochemical data and 30295 soil parent material data which were collected and analysed by two-layer gridding method were used to infer the barrier factors in the migration and transformation of selenium from soil to crop and human body. The total selenium average of soil, staple food and human body be counted, the soil selenium existing forms and the correlation analysis between soil aluminum trioxide, iron trioxide were analysed.The average content of topsoil selenium in Northeast China was 0.20 mg/kg, which was significantly lower than the world soil selenium content average (0.4 mg/kg) and slightly lower than the Chinese soil selenium content average (0.239 mg/kg).The average selenium content of human hair is only 0.16mg/kg in Baiquan, Heilongjiang Province. Soil-forming parent material has some influence on soil selenium content, however, epigenetic enrichment is a more significant enrichment factor on soil selenium content. Soil selenium existing in humic acid state selenium, strongly organic bound state selenium, and the contents of selenite, selenate and methyl selenocysteine which are easily used by plants are all relatively high, correlation analysis between soil selenium content and organic matter, iron and aluminium oxides shows that soil organic matter and iron and aluminium oxides were the main barrier factors for selenium migration and transformation. Lower soil selenium content may be the basic factor for the biogeochemical deficiency of selenium, the sequestration of selenium by clay chemical constituents such as iron and aluminium oxides and soil organic matter is the direct factor for the biogeochemical low selenium in the Northeastern China, which increasing the risk of KD in the population. These research findings can provide more evidence to assess the elimination of biogeochemical aetiology of diseases from a selenium nutrient perspective.