研究人員發(fā)現(xiàn)，在地球傳送到大氣的熱流中,，地球內(nèi)部放射性同位素衰變所產(chǎn)生的熱量占了其中一半,。新發(fā)現(xiàn)表明，地球形成之后的殘余原始熱的供應(yīng)還未消耗殆盡,。
作為 KamLAND合作研究組的一部分,，Itaru Shimizu和同事利用日本的一個(gè)探測(cè)器測(cè)量了反微中子流。反微中子流是同位素放射性衰變過(guò)程中產(chǎn)生出的帶電中性粒子,，以不產(chǎn)生影響的方式穿越地球,。研究人員發(fā)現(xiàn)在地球釋放的熱流中，鈾-238和釷-232的放射性衰變總共產(chǎn)生了其中20兆兆瓦的熱量,。這個(gè)數(shù)值是地球釋放熱量的一半,，表明還有另一半的熱量源于自地球誕生后持續(xù)冷卻所產(chǎn)生的熱流殘余。(生物谷 Bioon.com)
doi:1038/ngeo1205
PMC:
PMID:
Partial radiogenic heat model for Earth revealed by geoneutrino measurements
The KamLAND
The Earth has cooled since its formation, yet the decay of radiogenic isotopes, and in particular uranium, thorium and potassium, in the planet’s interior provides a continuing heat source. The current total heat flux from the Earth to space is 44.2±1.0?TW, but the relative contributions from residual primordial heat and radiogenic decay remain uncertain. However, radiogenic decay can be estimated from the flux of geoneutrinos, electrically neutral particles that are emitted during radioactive decay and can pass through the Earth virtually unaffected. Here we combine precise measurements of the geoneutrino flux from the Kamioka Liquid-Scintillator Antineutrino Detector, Japan, with existing measurements from the Borexino detector, Italy. We find that decay of uranium-238 and thorium-232 together contribute TW to Earth’s heat flux. The neutrinos emitted from the decay of potassium-40 are below the limits of detection in our experiments, but are known to contribute 4?TW. Taken together, our observations indicate that heat from radioactive decay contributes about half of Earth’s total heat flux. We therefore conclude that Earth’s primordial heat supply has not yet been exhausted.
