Molecular Dynamics Simulation Of Seawater Absorb Carbon Dioxide And Calculate The Diffusion Coefficient

Molecular dynamics simulation can not only study macroscopic properties of a substance, but also obtain the results of microscopic motions which can't be observed in a laboratory. Thus it is widely used in the fields of physics, chemistry and materials science. On the other hand, many theoretical calculations of ocean science are unsatisfactory, a number of which is closely related to molecular dynamics. So it is a useful try to introduce molecular dynamics method into ocean science. Till now, it is barely reported that molecular dynamics simulation is applied to ocean science. In this paper we employ the molecular dynamics simulation method to investigate the process of air-sea exchange flux of carbon dioxide. Our calculation results are summarized as follows, which indicate that the application of molecular dynamics in the ocean science field has certain feasibility.(1) The process of seawater absorbing carbon dioxide from atmosphere is simulated. The results manifest that the depth of CO2 diving into seawater is very shallow, and the CO2 molecules are mainly gathered in the vicinity of air-sea interface. So we believe that the molecular motions lead to small contribution to carbon dioxide storage in seawater.(2) The influence of concentration of atmospheric carbon dioxide on the process of seawater absorbing carbon dioxide from atmosphere is simulated. The dependences of solubility of CO2 in seawater and some data about the distribution of CO2 molecules on the concentration of atmospheric carbon dioxide are obtained. These results show that, along with the enhancement of the concentration of atmospheric carbon dioxide, the solubility of CO2 in seawater and the depth of CO2 diving into seawater increase, and the CO2 molecules are distributed in wider region.(3) The influence of temperature on the process of seawater absorbing carbon dioxide from atmosphere is simulated. It is suggested that the carbon dioxide molecules will be concentrated in a narrower space layer in the vicinity of air-sea interface when temperature increases.(4) The motions of seawater molecules and CO2 in seawater are investigated. The molecular diffusion coefficients of seawater and CO2 in seawater are acquired.