A Research Of Geochemical Characteristics And Bioavailability Of Selenium-Rich Soil In GaoGang,Guangdong Province

Selenium is one of the essential trace elements for animals and plants and has a very broad prospects of development and application.Selenium content in animals and plants mainly comes from the soil environment through the biological chain,so it is very vital to study the geochemical characteristics and bioavailability of selenium element in soil environment.This paper mainly uses kriging interpolation analysis N,P,K and their available states,B,Mo,Mn,Zn,Cu,Se and As,Cd,Cr,Hg,Pb,Ni and other elements in soil and classifies the content gradeof elements.Then the paper mainly describes the content distribution characteristics of selenium in the soil.And influencing factors,the morphological characteristics,the relationship between the total amount of selenium and the available selenium was explored and analyzed.At last it analyzes the effectiveness,that is,the selenium-enriched status of crops in the study area and the health level of residents’ selenium intake.The results show:(1)Geochemical characteristics of surface soil: the content of the total amount of soil macroelements nitrogen,N,P and K in the study area and their available forms,OM,trace elements B,Mo,Mn,Zn,Cu,Se and heavy metal elements such as As,Cd,Cr,Hg,Ni in soil is uneven distribution with significant spatial differences,the average value is greater than the background value,and there is an enrichment trend in the surface soil.On the contrary,Pb has a depletion trend in the topsoil.The soil in the study area is seriously acidified,the coefficient of variation of soil p H in the topsoil is relatively low,and the spatial difference of acidification degree is not large.(2)Soil geochemical problems in the study area: the surface soil nutrient elements N,P,K,Mn,B,Cu,Zn are deficient in a large area(deficient and relatively deficient areas account for more than 62.5% of the total area of ??the assessment area),and B is deficient in the whole area,and the area of ??organic matter deficiency is larger(accounting for 75%);in the study area the soil is seriously acidified,and the soil acidity and alkalinity in the whole area are acidic or strongly acidic(p H is between 4.22 and 6.88).(3)In the study area the average selenium content of the soil was 0.48 mg/kg,which is characterized Se enrichment in topsoil.Through the analysis of relevant factors soil Se content is mainly affected by the comprehensive effects of soil-forming factors,weathering and soil-forming transformation,soil physical and chemical properties(soil p H,OM),land use patterns and topography in the study area.The area is large,accounting for 62.33% of the study area.But the plant availability of soil selenium in the study area is low in natural state.(4)The bioavailability of soil selenium is obtained mainly through the detection and analysis of plant(early rice,late rice,peanut)sample data.The average contents of early rice and late rice and peanut were 0.066 mg/kg,0.046 mg/kg and 0.044 mg/kg,respectively,the corresponding bioconcentration coefficients were 34.44% and 13.2%,and the enrichment coefficient is 14.80%.The results of experimental analysis shows that the level of selenium content in plants mainly depends on soil available selenium.Therefore,the research and development of selenium-enriched agricultural products must focus on the soil available selenium content and its influencing factors,as well as various indicators such as soil p H,organic matter,ECE,and plant characteristics.(5)According to the dietary habits of residents in the study area,it is inferred that the daily intake of selenium in humans and the bioavailability of selenium.Among them,the bioavailability of selenium in rice is about 58.4%-68.5%.The PDI index(polymer dispersion index)is used to evaluate the health risk of selenium in the study area,and the PDI is calculated to be 29.59ug/d.According to the human selenium requirement standard,although food intake meets the minimum human selenium requirement of 17μg/day,it is lower than the human body’s physiological requirement of 40 μg/day.Therefore,the overall selenium dietary intake of the population in the Gaogang study area is relatively lacking,and there is a health risk of selenium deficiency.