Geochemical Characteristics And Distribution Of Selenium In Soil And Agricultural Products In Tiemenguan City

Selenium is one of the essential trace elements in the human body which is also an indispensable role in human health.This article takes Tiemenguan City,Xinjiang as the research area,and systematically collects samples of surface soil,irrigation water,atmospheric dust,fertilizers,crops,root soil,etc.to analyze beneficial and harmful elements such as selenium.The aim is to identify the content and distribution characteristics of selenium in the soil of the research area,analyze the sources of selenium in the soil,and study the factors affecting the enrichment of selenium in the soil;Analyze and evaluate the selenium rich levels in crops and root soil,and reveal the migration and enrichment patterns of selenium elements in the soil parent material soil agricultural products.The following results have been achieved through research:(1)The nutrient element levels in the surface soil of Tiemenguan area are mainly moderate and relatively deficient,accounting for 54%and 36.52%.The geochemical grade of environmental quality is mainly clean,accounting for 99.78%;This indicates that most of the soil in the study area is not polluted by heavy metals,and the overall environmental quality is good.The comprehensive geochemical grade of soil quality is mainly good and medium.The soil quality is relatively general,and nutrient elements are relatively scarce.(2)The content of selenium in the surface soil of the study area ranges from0.04-1.85mg/kg,with an average value of 0.35mg/kg,which is 1.24 times the background value of selenium in China’s soil(0.29mg/kg).The level of selenium content in the study area is mainly sufficient selenium and selenium rich,and a selenium rich area of about280km~2is delineated.(3)Soil selenium in Tiemenguan City is affected by many factors such as soil parent material,soil type,land use type,organic matter and p H value.Soil selenium mainly depends on soil parent materials,and limestone contributes the most to selenium in different soil parent materials.Among different land use types,the selenium content in grasslands and gardens is relatively high,followed by arable land,and the lowest in forest and unused land,indicating that the distribution of soil selenium in the study area is significantly affected by human activities.The selenium content in soil is significantly positively correlated with organic matter,and weakly negatively correlated with p H.(4)The main natural source of soil selenium in the study area is the secondary enrichment of soil forming parent material limestone after weathering.Among anthropogenic sources,atmospheric dust has the highest input of soil selenium,accounting for about 52%of the total input,followed by groundwater,and the lowest input of fertilizer.(5)The walnut and sunflower samples in the research area all meet the selenium enrichment standards,while the selenium enrichment rate of corn and jujube samples reaches over 64%.Moreover,the heavy metal content of crops such as corn,walnut,sunflower,and jujube does not exceed the standard,making them green and safe selenium rich agricultural products.