The Determination Of Selenium And The Interaction With Heavy Metals In Raphanus Sativus

Selenium is one of the essential nutritional elements, and has many importantphysiological functions. There have been many different ways that human can supplyselenium so far, and Se-enriched food is becoming more and more popular Thecheaper Se-enriched food is more easily accepted by ordinary consumers. Radish asan important economic crop, exhibit high quality and inexpensive, so investigatingthe planting conditions of Se-enriched Radish, cultivating and spreading ofSe-enriched radish have important values. The effect of heavy metals on cropgrowing is more and more serious because of the development of industry. Investigatethe chemical speciation and content of heavy metals and selenium, as well as theinteraction between heavy metals and selenium in Radish. This research will have apositive effect on development of selenium-rich crops in lightly heavy metal pollutedareas.1. In this thesis, through the optimization method of Selenium, Lead, Cadmiumin the samples determined by graphite furnace atomic absorption method, establishthe best method of Selenium, Lead, Cadmium in Radish determined by the graphitefurnace AAS. The results showed that1.0mg·mL^-1Cu（NO3）2as matrix modifier,7.0mA lamp current, ashing temperature800℃, atomization temperature2500℃were the optimum conditions of selenium determination in different Radish.5.0mAlamp current,260℃ashing temperature, atomization temperature1800℃were theoptimum conditions of Cadmium determination in the Radish.12.0mA lamp current,500℃ashing temperature, atomization temperature2200℃were the optimumconditions of Pb determination in radish. Under the optimized conditions, therecovery of Se was between99.6%¹06.0%, relative standard deviation was1.19%,the detection limit was0.79μg/L. The recovery rate of Cd was87.2%¹03.7%,relative standard deviation was4.40%. The recovery of Pb was96.7%¹23.9%,relative standard deviation was2.04%. The graphite furnace AAS is a simple,sensitive, stable method to determinate Selenium, Lead, Cadmium in plant samples,and it is suitable for Selenium, Lead, Cadmium determination in radish. 2. With the method of field test, three cultivars of Radish: red cherry radish,white radish, green fruit radish were Se-enriching cultivated. The concentrations ofselenium in three cultivars of Radish were positively related to Selenium in soils. Theselenium enrichment ability of three cultivars of radish: red cherry> green fruit>white cherry. By using reagent extraction agents, water, ethanol,0.1moL·L^-1acetic acid,0.1moL·L^-1NaCl,0.1moL·L^-1NaOH,0.05moL·L^-1NaHCO3,0.05moL·L^-1Tris-HCl,the different chemical speciation of selenium was extracted from the plants. Theresults showed that: in the samples protein bound selenium content were the mostabundant, the selenium content of alcohol soluble samples wre the least abundant,selenium was easier to combine with protein.3. In order to investigate the effects of different concentrations of Cadmium （Cd），Lead（Pb）, selenium（Se） and their combination on the growth of Radish and theuptake of Cd, Pb and Se in the plants, pot experiments are carried out. The resultsshowed that, a proper quantity of selenium could promote the growth of the Radish,showing up as Seed budding rate, leaf SPAD values,and biomass etc. Radish biomasswas negatively correlated with exogenous cadmium when radish was polluted by Cditself; cadmium inhibited the growth of radish. Pb leads poisonous effect on the partof radish on the ground, but only in the higher concentration will make (Lead>400mg·kg^-1) a great influence on the underground biomass. The concentration ofselenium in the soil had antagonistic effects on Cadmium and Lead, and promoted thegrowth of Radish. The absorption ability of selenium was stronger in root than inshoot, at the same time the root was obviously enriches more selenium than the shoot.In the composite effect of selenium and cadmium, no obvious effect on cadmiumuptake of low concentration of selenium; selenium can significantly reduce the Cdabsorbed by radish. the Se+Pb treatment group, the addition of Pb significantlyinhibits the growth of the radish, radish germination in10days seedlings all died; andgroup Pb+Se, radish maintain growth, selenium can significantly reduce theabsorption of Lead that is absorbed by radish, in addition, the average absorption ofLead drops40%.