Study On Heavy Metal Content And Soil Association Of Lycium Barbarum In Qinghai Province

In this study,the distribution characteristics of heavy metals and soil nutrients of Lycium barbarum from five main producing areas(Duran,Nomuhong,Golmud,Delingha,Wulan)in Qinghai Province were studied.The contents of Cd,Cr,Hg,Pb,As and eight soil nutrient indexes,including total phosphorus,total nitrogen,total potassium and so on,were tested by the national standard method,and evaluated according to the relevant evaluation criteria and methods.The correlation of heavy metal elements in Lycium barbarum soil,the correlation between dried fruit and soil heavy metals,and the correlation of soil main nutrients were further analyzed.The results show that:(1)The Hg,Pb,Cd 3 elements of heavy metals have some accumulation in the surface soil of the research area.The spatial variability of Pb is weak,and the rest elements belong to moderate spatial variation.All the elements in the soil of the total study area are safe except the Cd content which belongs to the alert level.Among the five heavy metal elements,Cd and Hg are the main minor risk factors.The content of Cd and Pb is relatively high.(2)The heavy metal content of Lycium barbarum in the research area was not seriously exceeded the standard,which was in accordance with the relevant standards in Chinese Pharmacopoeia.There were some differences in heavy metal contents among different regions.The contents of heavy metals in Golmud sample area were relatively high,and that in Delingha sample area was relatively low.There was a good synergistic effect between As-Cr,As-Pb elements in the dried fruit of Lycium barbarum,but there was no significant correlation between the contents of heavy metals in the fruit and the content of heavy metals in the soil.(3)The contents of total nitrogen,total potassium,alkali-hydrolyzed nitrogen,available potassium and organic matter had no significant difference.Eight soil physical and chemical indexes showed that the soil fertility index of Normuhong sample area was better than that of other sample areas.By comparing with the reference standard of fertility in "Environmental quality of Green Food producing area"(NYR / T391-2013),it was shown that the comprehensive characteristic of the five sample areas was that the OM content level was lower and the TN fertility level was generally superior to that of OP and AK.(4)Correlation analysis of soil nutrients and heavy metals showed that soil pH value was negatively correlated with other soil nutrients except TK.The increase of AN and pH in soil inhibited Cr in soil to a certain extent.The increase of TN and AN content inhibited Hg to some extent.