Preface:Value and dynamics of salt lakes in a changing world

The statement that the world’s ecosystems are rapidly deteriorating due to human intervention and global warming is nowadays commonplace.Some of the ecosystems most heavily impacted are inland salt lakes.The salt lakes are among the most valuable and fascinating ecosystems on Earth,and their study has both basic scientifi c interest as well as applied aspects.

Potential and limitations of satellite laser altimetry for monitoring water surface dynamics:ICESat for US lakes

Elevation measurements from the Ice,Cloud and Land Elevation Satellite(ICESat)have been applied to monitor dynamics of lakes and other surface water bodies.Despite such potential,the true utility of ICEsat--more generally,satellite laser altimetry--for continuously tracking surface water dynamics over time has not been adequately assessed,especially in the continental or global contexts.This study analyzed elevation derived from ICESat data for the conterminous United States and examined the potential and limitations of satellite laser altimetry in monitoring the water level dynamics.Owing to a lack of spatially-explicit ground-based water-level data,the high-fidelity land elevation data acquired by airborne lidar were firstly resorted to quantify ICESat’s ranging accuracy.Trend and frequency analyses were then performed to evaluate how reliably ICESat could capture water-level dynamics over a range of temporal scales,as compared to in-situ gauge measurements.The analytical results showed that ICESat had a vertical ranging error of 0.16 m at the footprint level-an lower limit on the detectable range of water-level dynamics.The sparsity of data over time was identified as a major factor limiting the use of ICESat for water dynamics studies.Of all the US lakes,only 361 had reliable ICESat measurements for more than two flight passes.Even for those lakes with sufficient temporal coverage,ICESat failed to capture the true interannual water-level dynamics in 32%of the cases.Our frequency analysis suggested that even with a repeat cycle of two months,ICESat could capture only 60%of the variations in water-level dynamics for at most 34%of the US lakes.To capture 60%of the water-level variation for most of the US lakes,a weekly repeated cycle(e.g.,less than 5 d)is needed-a requirement difficult to meet in current designs of spaceborne laser altimetry.Overall,the results highlight that current or near-future satellite laser missions,though with high ranging accuracies,are unlikely to fulfill the general needs in remotely monitoring water surface dynamics for lakes or reservoirs.

Scattering Resonance States and Partial Potential Energy Surface of Reaction I+HI(v=0)→IH(v′=0) +I

The partial potential energy surface of the I ＋ HI →IH ＋ I reaction involving the translational and vibrational motions has been constructed at the QCISD（ T ）//MP4SDQ level with the pseudo potential method that is helpful to interpreting the scattering resonance states. The lifetimes of the scattering resonance states in the title reaction obtained from the partial potential energy surface are about 90-120 fs, which agrees with the result of high-resolved threshold photodetachment spectroscopy of anion IHI^- measured by Neumark.

Theoretical Study of the Scattering Resonance State, Reaction Mechanism and Partial Potential Energy Surface of the F+CH4→HF+CH3 Reaction

The partial potential energy surface was constructed by ab initio method [QCISD（T）/6- 311＋＋G（2df,2pd）]for F＋CH4→HF＋CH3 reaction system. It not only explained the reaction mechanism brought forward by Diego Troya by means of quasiclassical trajectory （QCT） but also successfully validated Kopin Liu＇s experimental phenomena about the existence of the reactive resonance. The lifetime of the scattering resonance state was about 0.07 ps. All these were in agreement with the experiments.