Content,Enrichment And Migration Of Seleniumin Plants In Dashancun Area

Selenium is one of the important trace elements in natural ecological environment,which is closely relevant to the health of human and development of animals,plants.Selenium in plants comes from the soil circumstance,the absorption and accumulation of selenium by plants are affected by the form,abundance and other factors of selenium in the soil circumstance.The 72% terra in China is deficient in selenium,and the 1/3 terra meets serious selenium deficiency.There are many approaches for the flesh to refuel selenium.Among the approaches,dietary selenium supplementation is the most healthy,safe,convenient and effective approach.The dietary selenium-rich plants are main source of selenium supplementation,developing and utilizing them have become the focus of selenium-riched research.Dashancun is one of the most important selenium-rich areas in China,which is abounding in botanic resources such as selenium-rich tea,selenium-rich crops and selenium-rich Chinese traditional medicine herbs.This research takes botanic resources in Dashancun area as the subject to analyzes the accumulation,distribution and migration of selenium in the soil-plant system.The research contribute to the protection and reasonable utilization of selenium-rich plant resources such as selenium-rich Chinese traditional medicine herbs,selenium-rich esculent plants and selenium-rich crops with scientific basis in Dashancun area.The main research results are as follows:(1)Hydride generation-atomic fluorescence spectrometry with wet digestion by HNO3 and HCl O4 mixture was used to mensurate the total selenium content of soil and plants in Dashancun area.The condition for mensuration of trace selenium atomic fluorescence spectrometry were optimized.Under the optimum testing condition,the precision of this method is 1.15%,the detection limit is 0.165 ?g/L and the recovery range of the sample spiked recovery experiment is 95.37%-102.75%.(2)By means of the analysis and mensuration of total selenium content in 158 soil samples in Dashancun area: soil selenium content ranges from 0.161 to 7.189mg/kg and the arithmetic mean is 1.653 mg/kg.According to the categorization of the ecological landscape threshold value of selenium,the survey area is selenium-rich area.The selenium content in soil circumstance exists difference in different villages:the content in Yeshan Village is slightly higher than that in Dashancun area,both contents reach high selenium levels;the soil selenium content of Liuyuan Village and Lianhua Village is similar,both selenium contents are rich.In the three types of land use(woodland,farmland,tea garden),the soil are all positively correlated(P<0.01).The content of selenium in woodland soil is notably higher than that in farmland soil and tea garden soil.The result indicates that the selenium content in woodland soil is less disturbed by human activity.The woodland is conducive to the circulation and accumulation of selenium in soil system.(3)By the mensuration of selenium content in 362 samples(204 species of 176 genera in 99 families(Including bryophytes,pteridophyte and seed plants)involved)in Dashancun area.The range of selenium content in wild plants in the survey area is0.022-2.263 mg/kg,with an average value of 0.281 mg/kg.According to the categorization of the ecological landscape threshold value of selenium,the botanic selenium-rich rate reached 76.60%.The selenium-enriching ability of different kinds of plants is quite different: herbaceous plants(0.324 mg/kg)in wild seed plants is stronger than th abilit of trees(0.105 mg/kg),shrubs(0.156 mg/kg),woody vines(0.138mg/kg).The selenium contents of bryophytes and pteridophyte are generally higher,reaching 1.838 mg/kg and 0.411 mg/kg.(4)By the study for the selenium-enriching ability of edible plants and Chinese herb in Dashancun area,it is found that the selenium-enriching percent of edible selenium-rich plants is 70.59%.In different types of edible plants,selenium accumulation vary greatly.The accumulation sequences of 17 edible plants are as follow: Diospyros kaki > Brassica chinensis > Raphanus sativus > Brassica oleracea >Allium tuberosum>Pyrus spp>Zingiber officinale>Lactuca sativa>Camellia sinensis>Glycine max > Castanea mollissima > Allium chinense > Amorphophallus rivieri >Eriobotrya japonica>Allium sativum>Prunus salicina>Solanum tuberosum.According to the analysis,selenium contents vary greatly in 20 Chinese herbs,the contents comparation of the herbs which have different pesticide effect are as follows:Invigorating circulation blood and removing blood stasis type > Clearing and detoxifying type > Hemostasis type.The herb with pesticide effect of invigorating circulation blood and removing blood has relatively stronger selenium enriching and transporting ability.(5)Studies on the several types of selenium-enriched plants in Dashancun area indicates that the Osmunda japonica has higher selenium content(0.520 mg/kg),and the rhizome(0.853 mg/kg)and feathers(0.506 mg/kg)have stronger selenium accumulation faculty than the leaf axis(0.190 mg/kg).The selenium content of Cruciferae(0.648 mg/kg)and Sedum(0.454 mg/kg)reached the selenium-rich plant standard.Brassica campestris,Raphanus sativus,and Rorippa indica have strong selenium accumulation and enrichment ability,and their selenium content are over1 mg / kg,which are significantly higher than that in other types of plants.(6)This study convey a further clarification of the selenium migration and transformation law in the soil-plant system in Dashancun area.The research results provide a scientific basis for developing selenium-rich plant resources and kinds of selenium-rich agricultural products(such as selenium-rich Chinese herbs,selenium-rich edible vegetables and eg.)in Dashancun area.It also provide technical support for cultivating high-selenium plants,extracting organic selenides to manufacture biological agent products,and implementing the agricultural industrialization development of selenium functions.