Distribution Characteristics And Enrichment Mechanism Of Selenium In Topsoil Of Central And Western Handan

Selenium is an essential trace element for living organisms.The dual biological characteristics of Se lead to diseases caused by either too much or too little Se intake over a long period of time.Due to its nature,Se is unevenly distributed in soils and 72% of soils in China are classified as low-Se or Se-deficiency,with Hebei Province being generally Se-deficiency.However,the survey found that Se-enriched soils are clearly present in the central and western areas of Handan,and the stratigraphic outcrop is complex,with potential sources of Se.However,the survey found that Se-enriched soils are clearly present in the central and western areas of Handan.However,previous research only described the Se content in the eastern plain of Handan,and the distribution characteristics of Se content in the western mountainous and hilly areas are still in a blank area,and the stratigraphic outcrop is complex,with potential sources of Se.Therefore,this thesis takes the topsoil in the central and western areas of Handan City as the research object,and uses various statistical analysis methods to systematically study the characteristics of Se content and distribution patterns in the topsoil,to explore the enrichment factors and sources of Se in the soils,the effective Se content of the soils and the controlling factors,and finally to comprehensively evaluate the soil quality in the study area.Through the analysis of 192 topsoil samples,it was found that Se content of topsoil in the study area ranged from 0.00 to 1.95 μg/g,with an average value of 0.45 μg/g,of which 42.19% of the soil samples met the Se enrichment standard.The Se-enriched belt in the study area is mainly located in the hilly area to the east of the Taihang Mountains to the west of Handan City,and in the plain area near Handan City,especially in Handan City,Yongnian District,Fengfeng Mining District and Wu’an City.Pearson correlation analysis was used to study the enrichment mechanism of Se in soils,and it was found that the enrichment of Se was related to the influence of oxides,heavy metal elements and organic matter.Cluster analysis and principal component analysis showed that Se in the topsoil was mainly influenced by the combination of heavy metal elements Cd and Pb,as well as siderophile and sulfophilic elements,which in turn judged that Se in the soil originated to some extent from the weathering deposits of exposed rocks.Due to natural factors,the Se-enriched soils in the mountains in the western part of the study area are mainly enriched by weathering of Se-enriched bedrock;due to anthropogenic factors,the Se-enriched soils in the central plains of the study area are mainly enriched by pollution caused by coal mining and transportation.The Se content of each form in the soil was investigated through a step-by-step chemical extraction experiment,which revealed that the effective Se content of the soil ranged from 3% to 24%,with an average of 0.0089 μg/g in the water-soluble state,which is a high Se environment.The effective Se content of the soil is controlled by the whole Se content,the organic matter and the Se content of each form.According to the Nemerow Integrated Pollution Index,large areas to the east and west of the study area are mainly in safe areas,while large areas in the central part are at potential pollution levels.On the whole,the effective Se resources in the study area are relatively abundant,and the soil quality is in good condition.,and therefore has a good basis for the production of Seenriched agricultural products.The superimposed selection of Se-enriched soils as well as environmentally clean soils as high-quality resource areas provides a reference for the rational development of local Se-enriched agricultural products.