海表扩散层中气体行为的分子动力学模拟

Molecular dynamics simulation of gas behaviors in seawater diffusive layer beneath the air-sea interface

尽管影响气体在海气界面间交换的因素很多,但迄今却仅仅用风速来估算气体在海气界面的传输速度。另一方面,直接实验测量气体在海气界面的传输也十分困难。因此,气体穿过海气界面的传输速度仍然存在很大的不确定性。文章采用分子动力学方法模拟了二氧化碳、氧气、氮气以及惰性气体氩、氪在海表扩散层内部的扩散过程,求得不同温度下这些气体的扩散系数,与现有的实验值平均相差约19.4%,并重点讨论了二氧化碳在扩散层内部的行为,为进一步研究气体在海气界面的传输速度提供了新的理论手段。

Despite of the many processes that affect gas exchange at the air-sea interface, up to now wind velocity is typically the only factor that is used to estimate gas transfer velocity. On the other hand, it is so hard to directly measure the gas transfer at the air-sea interface. Because of this difficulty, large uncertainties still remain on gas transfer velocity. Using molecular dynamics simulation, the seawater property and the motions of CO2, O2, N2, Ar, and Kr in the diffusive layer beneath the air-sea interface are investigated. Then, their diffusion coefficients at different temperatures are calculated. The detail of CO2 behaviors is discussed as well. The molecular dynamics simulation will be a new theoretical tool for calculating the gas transfer velocity in the future.