Distribution Characteristics And Influencing Factors Of Selenium In Soil Of Abnormal Selenium Area In Central Guangxi

Selenium is an essential trace element for human body and animal.Deficiency or excess of selenium will affect the health of human body.In the soil-plant-animal system,soil is the main source of selenium for the growth of animals and plants.Existing research results show that the distribution of karst landform is the most typical clusters and the nation’s largest selenium-rich soil shall area,karst region Gui Zhong soil selenium content is higher,its selenium background value of 0.52 mg/kg,far higher than the background value of 0.2 mg/kg,is an important selenium-rich soil distribution area,guangxi is high geological background of soil heavy metals.In this paper,qintang District of Guigang and Hengxian County of Nanning are selected as the study areas,and four geological survey and sampling zones are arranged along the vertical stratigraphic trend.88 rock samples and 98 soil samples are collected respectively.By using hydride atomic fluorescence spectrophotometry-88 rock samples and the Se content of 98 soil samples,using inductively coupled plasma emission spectrometry 98 soil samples of Al,Cr,Cu,Fe,Mn,Ni,Ti,zinc and other elements,discusses the Se and the characteristics of distribution of heavy metals and coexistence relationship,The factors affecting the distribution of Se and these heavy metals in soil were analyzed,and the following conclusions were drawn:1.The average selenium content of rocks in the study area is 0.15mg/kg,the median is0.019mg/kg,and the coefficient of variation is 227.41%.The relatively se-rich rocks are distributed in devonian,Carboniferous and Permian strata,and the selenium enrichment coefficients are 1.92,0.41 and 6.83,respectively.The number of samples exceeding the crustal abundance accounts for 27.27%,16.34% and 90.00%,respectively.Siliceous rock and limestone have the highest selenium content,0.513mg/kg and 0.104mg/kg,respectively.2.The soil selenium content in the study area ranged from 0.08 mg/kg to 4.08mg/kg,with an average of 0.87mg/kg and a coefficient of variation of 65.24%.About 96.94% of the samples had a soil selenium content greater than 0.175mg/kg,of which 18.37% had sufficient selenium and 77.55% had rich selenium.3.The average value of selenium in different strata is as follows: Triassic < Devonian <Permian < Carboniferous;The coefficient of variation was as follows: Triassic(28.74%)<Devonian(55.86%)< Carboniferous(65.45%)< Permian(145.19%).Except for the Triassic,the selenium content in the soil of the other geological ages has reached a medium(> 50%)or above variation,and the Permian has reached a strong variation level,indicating that the distribution of selenium content in the soil of the formation is very uneven,which may be affected by the sedimentary period or tectonic environment.4.The soil Al,Cr,Cu,Fe,Mn,Ni,Ti and Zn are enriched in the study area.Soil p H and content of Cu,Fe,Ni,Cr,Ti and Mn all affect soil Se content.When the soil p H,the higher the content of Cu,Fe minerals in the soil,the more likely to appear abnormal high selenium soil,vice versa.