Figure 6

Constraining the extent of the Earth atmosphere missing Xe (a) Discrepancy between the ⁸⁴Kr/¹³²Xe of the initial atmosphere, as formed by the mix of comets and chondrites (Table 1), and its present-day ⁸⁴Kr/¹³²Xe permits the amount of lost atmospheric Xe to be derived as a function of the ⁸⁴Kr/¹³²Xe of the chondritic end-member (7.5–23 Xe atmospheric masses lost). The thick brown and blue curved lines represent the medians of distribution for mixing with EC and CC, respectively. (b) Discrepancy between the ⁸⁴Kr/¹³²Xe of comet 67 P/C-G (4.7 ± 1.1)³¹ and the calculated cometary Kr and Xe contributions (~20%) enables the extent of atmospheric Xe loss to be estimated (3–11.5 Xe atmospheric masses lost). The “common” range: the only possibility for the extent of Xe loss from the atmosphere is at the intersection between 7.5–23 ATM_Xe and 3–11.5 ATM_Xe, i.e. ~8 to 12 ATM_Xe being missing from the present-day inventory. See methods for details on computation.