Lapho amazinga aphezulu e-trace element molybdenum (mah-LIB-den-um) etholwa emithonjeni yamanzi okuphuza eningizimu-mpumalanga ye-Wisconsin, izindawo eziningi zesifunda zokulahla umlotha wamalahle zibonakala zingaba umthombo walokhu kungcola.

Kodwa omunye umsebenzi wabaseshi owenziwe kahle oholwa abacwaningi baseDuke University kanye ne-Ohio State University uveze ukuthi amachibi, aqukethe izinsalela zamalahle ashiswe ezimbonini zikagesi, awawona umthombo wokungcola.

Isuka emithonjeni yemvelo esikhundleni salokho.

"Ngokusekelwe ekuhlolweni okusebenzisa 'izigxivizo zeminwe' ze-forensic isotopic nezindlela zokuqomisana ubudala, imiphumela yethu inikeza ubufakazi obuzimele bokuthi umlotha wamalahle awuwona umthombo wokungcola emanzini," kusho u-Avner Vengosh, uprofesa we-geochemistry kanye nekhwalithi yamanzi eDuke's Nicholas School of. Imvelo.

"Ukube la manzi anothe nge-molybdenum avela ekucwilisweni komlotha wamalahle, ngabe mancane, njengoba aphinde afakwa emanzini angaphansi komhlaba esifunda asuka emlotheni wamalahle eminyakeni engu-20 noma engu-30 kuphela edlule," kusho uVengosh. "Esikhundleni salokho, izivivinyo zethu zikhombisa ukuthi iphuma ekujuleni komhlaba futhi ineminyaka engaphezu kuka-300 ubudala."

Ukuhlola kuphinde kwembula ukuthi izigxivizo zeminwe zamanzi angcolile - izilinganiso zawo ezinembile ze-boron ne-strontium isotopes - azifani nezigxivizo zeminwe ze-isotopic zezinsalela zokuvutha kwamalahle.

Lokhu okutholakele “ku-de-link” i-molybdenum evela ezindaweni zokulahla umlotha wamalahle futhi esikhundleni salokho kusikisela ukuthi ingumphumela wezinqubo zemvelo ezenzeka ku-matrix yedwala le-aquifer, kusho uJennifer S. Harkness, umcwaningi wangemva kodokotela e-Ohio State obehola ucwaningo njengengxenye. ngeziqu zakhe zobudokotela eDuke.

Abacwaningi bashicilele iphepha labo elibuyekezwe ngontanga kule nyanga kumagazini i-Environmental Science & Technology.

Inani elincane le-molybdenum libalulekile empilweni yezilwane nezitshalo, kodwa abantu abayidla kakhulu basengozini yezinkinga ezihlanganisa i-anemia, ubuhlungu bamalunga kanye nokundindizela.

Eminye yemithombo ehlolwe eningizimu-mpumalanga yeWisconsin iqukethe ama-micrograms angu-149 e-molybdenum ilitha, okungaphezudlwana okuphindwe kabili kwezinga lezinga lokuphuza eliphephile le-World Health Organization, elingama-microgram angu-70 ilitha. I-US Environmental Protection Agency ibeka umkhawulo ongaphansi ngisho nangaphansi kokuthi ama-microgram angu-40 ilitha.

Ukwenza ucwaningo olusha, u-Harkness nozakwabo basebenzisa ama-tracers e-forensic ukuze bathole izilinganiso ze-boron ne-strontium isotopes kusampula ngayinye yamanzi. Baphinde balinganisela isampula ngayinye ye-tritium ne-helium isotopes enemisebe, anamazinga okubola angaguquki futhi angasetshenziswa ukuhlola ubudala besampula, noma “isikhathi sokuhlala” emanzini angaphansi komhlaba. Ngokuhlanganisa la maqoqo amabili okutholakele, ososayensi bakwazi ukuhlanganisa ulwazi oluningiliziwe mayelana nomlando wamanzi angaphansi komhlaba, okuhlanganisa nokuthi angena nini okokuqala endaweni engaphansi komhlaba, nokuthi yiziphi izinhlobo zamadwala ayehlangane nazo ngokuhamba kwesikhathi.

“Lokhu kuhlaziya kuveze ukuthi amanzi ane-molybdenum ephezulu awaveli emithonjeni yomlotha wamalahle ngaphezulu, kodwa avela kumaminerali anothe nge-molybdenum ku-aquifer matrix kanye nezimo zemvelo ku-aquifer ejulile evumela ukudedelwa kwale molybdenum emanzini. amanzi angaphansi komhlaba,” kuchaza uHarkness.

“Okuhlukile ngale phrojekthi yocwaningo ukuthi ihlanganisa izindlela ezimbili ezihlukene—izigxivizo zeminwe ze-isotopic kanye nokuqomisana neminyaka—ukwenza ucwaningo olulodwa,” kusho yena.

Nakuba ucwaningo lugxile emithonjeni yamanzi okuphuza e-Wisconsin, okutholakele kungase kusebenze kwezinye izifunda ezine-geologies efanayo.

UThomas H. Darrah, uprofesa ohlangene wezesayensi yomhlaba e-Ohio State, ungumeluleki we-postdoctoral ka-Harkness e-Ohio State futhi wayengumbhali-ndawonye wocwaningo olusha.