Study On The Migration And Distribution Of Arsenic In The Soil Of Tea Gardens In Changning County, Yunnan Province

Tea is one of the main drinks in people's lives,and now people increasingly concern about heavy metal content in tea.Research on the main pollutant Arsenic(As)in tea-garden soil,which provides theoretical references for the safe use of teagarden soil in future.On the basis of previous research,this paper uses the combination of X-ray fluorescence spectrometer(XRF)data and laboratory test data,to focus on studying the migration of As in the soil system of tea-garden in Changning County,Yunnan.Firstly,we collected soil and tea leaves samples from the tea-garden in Songshan Village,Wenquan Town,Changning County,and used XRF to detected the total As content of the soil on site.We also recorded soil texture,elevation,slope and all other on-site environmental information of the sampling site.Secondly,we tested the effective state of As content in soil and tea in the laboratory..Thirdly,we used SPSS(19.0)for correlation analysis,and applied MATLAB(R2020B)for regression model establishment.Researched on the following subjects:1.application of XRF to detect As content in tea-garden soil,2.the migration of As between soil and tea,3.the influence of tea-garden topography on the migration of As in the soil.Further more,we analyzed the migration law of As in the tea-garden soil system.The results show:1.This experiment studied the applicability of XRF in the detection of total As content in tea-garden soil.The correlation coefficients of XRF field test data and laboratory test data are different under different pH values,soil textures and soil As content,.In an acidic soil environment with pH>5.0,the correlation coefficient between XRF field test data and laboratory test data is the largest(p<0.01),and the correlation coefficients are in order:(pH>5.0)>(4.5<pH?5.0)>(pH?4.5);In the sandy soil texture,the correlation coefficient between XRF field test data and laboratory test data is the largest(p<0.01),and the correlation coefficient is in order: sandy soil>loam>clay soil;When the total As content in tea-garden soil is greater than40mg/kg,the correlation coefficient between XRF field test data and laboratory test data is the largest(p<0.01),and the correlation coefficients are as follows:(total As content in soil 10-40mg/kg)>(total As content in soil?10mg/kg)>(total As content in soil>40mg/kg).At the same time,the average value and standard deviation of the XRF field test data are higher than the laboratory test data,and its minimum and maximum values are also higher than the laboratory test data,and the XRF field test data is generally higher.2.This experiment studied the migration of As between tea-garden soil and tea leaves.In tea-garden with different degrees of acidic soil and different soil textures,the correlation between the content of As in the soil and the enrichment coefficient and the content of As in the soil and the transmission coefficient is affected by the pH value.Among them,in the environment of pH ? 4.5,the correlation between the content of As in the soil and the enrichment coefficient and the content of As in the soil and the transmission coefficient are all negatively significant(p<0.01),and as the pH value increases,The correlation coefficient shows a downward trend,and the correlation changes from significant to insignificant.On the contrary,as the pH value decreases,the correlation coefficient is the highest.The more active As is in teagarden soil,the easier it is to be absorbed by tea;in sandy soil and loam soil textures of soil,the correlation between the As content in the soil and the enrichment coefficient and the As-available state content in the soil and the transfer coefficient also showed negative significant,indicating that the mobility of As in tea-garden soil is stronger than that in clay soil under these two soil textures.At the same time,whether it is from the perspective that the average As content in tea is higher than the average As available state in the soil,or from the perspective that the As content in tea exceeds the standard,but the total As content in the soil does not exceed the standard,the analysis is carried out through the previous research As in the soil of local tea-garden comes from agricultural inputs.In summary,tea(old leaves)accumulates As in the soil.3.This experiment studied the influence of the topography of the tea-garden on the migration of total As in the soil.The total As content in the tea-garden soil has a significant correlation with the height and slope of the tea-garden.Under the combined effect of tea-garden elevation and slope,as the elevation decreases and the slope becomes smaller,the total As content in the tea-garden soil gradually increases.And at a certain elevation and slope,the total As content in the tea-garden soil increases.Under the combined effects of slope and elevation,the As content in teagarden soil migrates to areas with low altitude and gentle slope area,mainly at the highest elevation of 1988 m and the highest slope 52° of the area.The total As content in tea-garden soil is only 1.81mg/Kg.The total As content in the tea-garden soil is as high as 74.3 mg/kg at the lowest elevation of 1924 m and the lowest slope of 2° in the area,which is 40 times higher..