Geochemical Cov yam ntxwv ntawm Selenium
Selenium yog ib yam khoom tsis yog-hlau uas muaj cov ntsiab lus nruab nrab ntawm kwv yees li 0.05 mg / kg hauv lub ntiaj teb crust, faib nws raws li cov khoom tsis tshua muaj. Nws feem ntau tshwm sim raws li isomorphous cov ntaub ntawv nyob rau hauv sulfide minerals (xws li pyrite thiab galena), thiab kuj muaj nyob rau hauv shale, thee- bearing strata, thiab volcanic pob zeb. Selenium muaj nyob rau hauv ntau lub xeev valence nyob rau hauv qhov xwm txheej (-2, +4, +6), thiab nws bioavailability yog ze ze rau nws daim ntawv: organic selenium (xws li selenomethionine thiab selenocysteine) yog yooj yim absorbed thiab siv los ntawm cov kab mob ntau dua inorganic selenium (selenite thiab selenate).
Cov xwm txheej rau Kev Tsim Cov Selenium-Enriched Mineral Dej
Kev tsim ntawm ntuj selenium- cov dej ntxhia muaj txiaj ntsig yuav tsum muaj peb yam tseem ceeb:
Selenium- nplua nuj niam txiv pob zeb los yog av: Lub cheeb tsam geological keeb kwm yav dhau yuav tsum muaj pob zeb los yog sediments nrog cov ntsiab lus selenium siab. Piv txwv li, cov shale dub (carbonaceous siliceous shale), thee - bearing strata, thiab volcanic clastic pob zeb dav faib nyob rau sab qab teb Tuam Tshoj tuaj yeem muaj cov ntsiab lus selenium txij li ntau pua mus rau txhiab micrograms ib gram.
Tsim nyog hydrogeochemical ib puag ncig: Cov dej hauv av yuav tsum tau txo qis lossis nruab nrab pH theem thaum nws ntws los pab txhawb kev tsiv teb tsaws ntawm selenium los ntawm cov khoom mus rau theem ua kua. Yog hais tias cov dej hauv lub cev muaj zog oxidizing los yog acidic, selenium nyhav nyob twj ywm li insoluble precipitates.
Ntev -Lub sijhawm ruaj khov hauv av hauv av: Cov dej sib sib zog nqus los yog karst fissure dej ntws maj mam hauv qhov chaw kaw tau ntau xyoo lossis ntau pua xyoo, sib pauv ions nrog cov pob zeb nyob ib puag ncig, yog li ua kom muaj ntau yam khoom muaj txiaj ntsig, suav nrog selenium.
Hom selenium- nplua nuj geological units hauv Suav teb:
The northern margin of the Yangtze Block black shale belt: Covering southern Shaanxi, western Hubei, eastern Chongqing, and western Hunan, this is China's largest and most typical selenium-rich area. The selenium content in the Cambrian-Silurian black shale in this region is generally >3 mg / kg, thiab hauv zos tshaj 10 mg / kg.
South China red soil selenium-rich area: Deep red soil has developed from the weathered crust of granite in Jiangxi, Guangdong, and Fujian provinces. In some areas, the soil selenium content is >0.4 mg / kg, thiab dej hauv av tuaj yeem nqa selenium mus rau hauv cov dej ntws los ntawm leaching.
Selenium- cov phiab nplua nuj nyob rau hauv arid Northwest Tuam Tshoj: Xws li Ili River Valley hauv Xinjiang thiab Tongren Basin hauv Qinghai, muaj cov selenium siab nyob rau hauv cov dej hauv av vim evaporation thiab concentration cuam tshuam.
Selenium- thaj chaw nplua nuj pob zeb roob hluav taws: Xws li thaj chaw ntawm Zhejiang thiab Fujian xeev, qhov chaw volcanic ejecta yog nplua nuj nyob rau hauv kab, tsim selenium- cov dej nplua nuj tom qab huab cua.
