Yung Y L, Wen J S, Moses J I, Landry B M, Allen M, Hsu K J
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, USA.
J Geophys Res. 1989 Oct 20;94(D12):14971-89. doi: 10.1029/jd094id12p14971.
A comprehensive one-dimensional photochemical model extending from the middle atmosphere (50 km) to the exobase (432 km) has been used to study the escape of hydrogen and deuterium from the Earth's atmosphere. The model incorporates recent advances in chemical kinetics as well as atmospheric observations by satellites, especially the Atmosphere Explorer C satellite. The results suggest: (1) the escape fluxes of both H and D are limited by the upward transport of total hydrogen and total deuterium at the homopause (this result is known as Hunten's limiting flux theorem); (2) about one fourth of total hydrogen escape is thermal, the rest being nonthermal; (3) escape of D is nonthermal; and (4) charge exchange and polar wind are important mechanisms for the nonthermal escape of H and D, but other nonthermal mechanisms may be required. The efficiency to escape from the terrestrial atmosphere for D is 0.74 of the efficiency for H. If the difference between the D/H ratio measured in deep-sea tholeiite glass and that of standard sea water, delta D = -77%, were caused by the escape of H and D, we estimate that as much water as the equivalent of 36% of the present ocean might have been lost in the past.
一个从中间大气（50千米）延伸至外逸层底部（432千米）的综合一维光化学模型已被用于研究氢和氘从地球大气中的逃逸。该模型纳入了化学动力学的最新进展以及卫星的大气观测数据，特别是大气探测者C卫星的数据。结果表明：（1）H和D的逃逸通量受均质层顶处总氢和总氘向上输送的限制（这一结果被称为亨滕极限通量定理）；（2）总氢逃逸量的约四分之一是热逃逸，其余是非热逃逸；（3）D的逃逸是非热逃逸；（4）电荷交换和极风是H和D非热逃逸的重要机制，但可能还需要其他非热机制。D从地球大气中逃逸的效率是H逃逸效率的0.74倍。如果深海拉斑玄武岩玻璃中测得的D/H比值与标准海水的D/H比值之差δD = -77%是由H和D的逃逸造成的，我们估计过去可能已经损失了相当于当前海洋36%的水量。
