Bioavailability Of Red Soil Selenium In Low Mountains And Hills And Assessment On Dietary Selenium Intake Of The Local Residents

Objective: Based on important physiological functions of Se, and diet is a mainchannel of human Se intake, in this paper,we discussed the bioavailability of Se inthe soils of low hilly red earth region, made assessment on nutritional status of dietarySe for local residents.Method: In this study,72surface soil samples and72parts of paddy rice plantsin typical low mountains and hills were collected, total Se in soils, differentspeciations of Se in soils and total Se in different parts of rice plants were detectedwith hydride generation-atomic fluorescence spectroscopy; meanwhile, pH, organicmatter and other physical&chemical indexes of soil samples were detected withmethods in national standards. After that, distribution and migration characteristics ofSe in soil-rice system and their influence factors were analyzed, bioavailability ofdifferent speciations of Se in soils was especially discussed in depth. Finally,according to Se content of rice and dietary survey of urban and rural residents inJiangxi province, Se intake of local residents was estimated and correspondingevaluations were pointed out.Results:(1) Average content of Se in soil and rice was respectively0.238±0.117mg kg-1and0.052±0.027mg kg-1. With reference to standard value ofenvironmental Se and health threshold value, Se content was in the medium level.(2) Average content of different speciations of Se in soils were ranked fromhigher to lower as follows: residual Se (116.82μg kg-1)> acid soluble Se (33.87μgkg-1)> organic combined Se (30.45μg kg-1)> water soluble Se (16.58μg kg-1)>exchangeable Se (15.11μg kg-1). Correlation analysis showed that organic matter insoil was positively correlated with total Se content and content of different speciations of Se. Soil pH had no significant correlation with them.(3) Se content in different parts of rice plants were ranked from higher to loweras follows: root (0.338mg kg-1)> leaf (0.074mg kg-1)> rice (0.052mg kg-1)> ricebran (0.040mg kg-1)> stem (0.036mg kg-1). Migration coefficient of Se betweenstems and leaves was the highest, and stems had the closest relation with Se content in edible parts of rice plants. Content of water soluble Se and exchangeable Se wasaccounted for about15%of total Se, they were significantly positively correlatedwith Se in roots and rice, all of above showed that the two parts had high activity.(4) It is estimated that dietary Se intake of local residents was36.37μg d-1, thevalue was a little lower than physiological demand of healthy adults(40μg.d-1),certainly, the value did not meet the recommended nutrient intakes of Se（50μg d-1）.Conclusion: In low mountain hilly red soil region with medium Se level, Secontent of rice is positively correlated with total Se in soils, water soluble Se in soilsand exchangeable Se in soils, especially, water soluble Se in soils and exchangeableSe in soils are more closer related to Se content of rice, therefore, bioavailability ofthe two speciations of Se for rice is higher than that of other speciations, it isestimated that dietary Se intake of local residents can not meet human requirements,it may cause harmful effects on health of local residents...