Thaum muaj qib siab ntawm cov kab mob molybdenum (mah-LIB-den-um) tau tshawb pom hauv cov dej haus hauv sab qab teb sab hnub tuaj Wisconsin, thaj av ntau qhov chaw pov tseg cov hmoov tshauv zoo li yog qhov muaj feem cuam tshuam rau kev sib kis.

Tab sis qee qhov kev tshawb pom zoo ua haujlwm coj los ntawm cov kws tshawb fawb los ntawm Duke University thiab Ohio State University tau qhia tias cov pas dej, uas muaj cov seem ntawm cov thee hlawv hauv cov nroj tsuag hluav taws xob, tsis yog lub hauv paus ntawm kev sib kis.

Nws stems los ntawm natural sources xwb.

"Raws li kev sim siv forensic isotopic 'tus ntiv tes' thiab cov txheej txheem hnub nyoog, peb cov txiaj ntsig tau muab pov thawj ywj pheej tias cov hmoov tshauv tsis yog qhov chaw paug hauv dej," said Avner Vengosh, tus xibfwb ntawm geochemistry thiab dej zoo ntawm Duke's Nicholas School of Ib puag ncig.

"Yog tias cov dej nplua nuj molybdenum no tau los ntawm cov leaching ntawm thee tshauv, nws yuav tseem hluas, tau rov qab mus rau hauv thaj av cov dej hauv av los ntawm cov av tshauv ntawm cov av tsuas yog 20 lossis 30 xyoo dhau los," Vengosh hais. "Xwb, peb qhov kev ntsuam xyuas pom tias nws los ntawm qhov tob hauv av thiab muaj ntau dua 300 xyoo."

Cov kev ntsuam xyuas kuj tau qhia tias cov dej tsis huv ntawm cov isotopic ntiv tes-nws qhov tseeb piv ntawm boron thiab strontium isotopes-tsis phim cov ntiv tes isotopic ntawm cov coal combustion residuals.

Cov kev tshawb pom no "de-link" molybdenum los ntawm cov chaw pov tseg cov hmoov tshauv thee thiab es tsis txhob hais tias nws yog qhov tshwm sim ntawm cov txheej txheem ntuj tsim nyob rau hauv lub aquifer lub pob zeb matrix, Jennifer S. Harkness, tus kws tshawb fawb tom qab kawm tiav hauv Ohio State uas tau coj txoj kev tshawb fawb los ua ib feem. ntawm nws tus kws kho mob dissertation ntawm Duke.

Cov kws tshawb fawb tau luam tawm lawv cov ntawv txheeb xyuas cov phooj ywg lub hlis no hauv phau ntawv xov xwm Environmental Science & Technology.

Cov me me ntawm molybdenum yog qhov tseem ceeb rau tsiaj thiab nroj tsuag lub neej, tab sis cov neeg uas noj ntau dhau ntawm nws ua rau muaj kev pheej hmoo ntawm cov teeb meem uas suav nrog ntshav qab zib, mob pob qij txha thiab tshee.

Qee lub qhov dej tau sim nyob rau sab qab teb sab hnub tuaj Wisconsin muaj txog 149 micrograms ntawm molybdenum ib liter, me ntsis ntau dua ob npaug ntawm cov qauv kev haus dej nyab xeeb ntawm World Health Organization, uas yog 70 micrograms ib liter. Lub Chaw Saib Xyuas Kev Tiv Thaiv Ib puag ncig Asmeskas tau teeb tsa qhov kev txwv txawm tias qis dua ntawm 40 micrograms ib liter.

Txhawm rau ua txoj kev tshawb fawb tshiab, Harkness thiab nws cov npoj yaig siv cov ntaub ntawv pov thawj los txiav txim siab qhov sib piv ntawm boron rau strontium isotopes hauv txhua qhov qauv dej. Lawv kuj ntsuas txhua tus qauv tritium thiab helium radioactive isotopes, uas muaj qhov lwj tsis tu ncua thiab tuaj yeem siv los ntsuas tus qauv hnub nyoog, lossis "lub sijhawm nyob" hauv av. Los ntawm kev sib koom ua ke ntawm ob qhov kev tshawb pom no, cov kws tshawb fawb tau tuaj yeem sib sau ua ke cov ncauj lus kom ntxaws txog keeb kwm dej hauv av, suav nrog thaum nws xub nkag mus rau hauv dej hiav txwv, thiab hom pob zeb twg nws tau cuam tshuam nrog lub sijhawm.

"Qhov kev soj ntsuam no tau qhia tias cov dej molybdenum siab tsis yog los ntawm cov av tshauv ntawm cov pob zeb hauv av, tab sis yog los ntawm molybdenum-nplua nuj minerals nyob rau hauv aquifer matrix thiab ib puag ncig tej yam kev mob nyob rau hauv lub sib sib zog nqus aquifer uas tso cai rau tso tawm ntawm molybdenum mus rau hauv lub aquifer matrix. dej hauv av," Harkness piav qhia.

"Dab tsi yog qhov tshwj xeeb ntawm txoj haujlwm tshawb fawb no yog tias nws koom ua ke ob txoj hauv kev sib txawv - isotopic ntiv tes thiab hnub nyoog hnub nyoog - rau hauv ib qho kev tshawb fawb," nws hais.

Txawm hais tias txoj kev tshawb fawb tsom mus rau qhov dej haus hauv Wisconsin, nws qhov kev tshawb pom muaj peev xwm siv tau rau lwm thaj chaw uas muaj geology zoo sib xws.

Thomas H. Darrah, tus kws tshaj lij ntawm lub ntiaj teb kev tshawb fawb ntawm Ohio State, yog Harkness tus kws pab tswv yim tom qab tus kws kho mob hauv Ohio State thiab yog tus kws sau ntawv ntawm txoj kev tshawb fawb tshiab.