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Adsorption kinetics of platinum group elements onto macromolecular organic matter in seawater
Kai Liu, Xuelu Gao, Qianguo Xing, Fushan Chen
doi: 10.1007/s13131-019-1433-3
Adsorption kinetics of the interaction between Pt, Pd and Rh (defined here as platinum group elements, PGEs) ions and macromolecular organic compounds (MOCs, >10 kDa), including humic acid, carrageenan and bovine serum albumin, and different cutoff fractions of natural organic matter (>1 kDa and >3 kDa) obtained from seawater using centrifugal ultrafiltration devices were investigated. For a given element, all the adsorption kinetics did not reach equilibrium except the interaction between Pt and >1 kDa cutoff, and between Pd and humic acid. For all the tested MOCs, the adsorption kinetics could be divided into two stages, a rapid adsorption process in the first 8 h and the desorption stage after the first 8 h until the equilibrium. The change trend of partition coefficient (log10Kd) values with experiment time was consistent with that of the kinetic curves. However, in the interaction between PGE ions and natural dissolved organic matter (NDOM), an obvious difference in the change trends of log10Kd and kinetic curves was observed. It indicated that the partition behavior of PGE ions interacting with NDOM in seawater was a combined effect of different organic constituents. The adsorption and log10Kd of PGEs in the >1 kDa NDOM fraction were higher and more stable than those in the >3 kDa NDOM fraction. The results also indicated that the 1–3 kDa NDOM may dominate the interaction between PGEs ions and NDOM. Moreover, no kinetic model could perfectly simulate the adsorption process. It indicated that the colloidal struction and morphology of MOCs or NDOM in seawater might be inhomogeneous. Hence, the interaction between PGE ions and organic matter in seawater was a complicated process and needs further research.
key words: adsorption, kinetics, platinum group elements, macromolecular organic compounds, natural organic matter, seawater
Sensitivity of WRF simulated typhoon track and intensity over the South China Sea to horizontal and vertical resolutions
Zhiyuan Wu, Changbo Jiang, Bin Deng, Jie Chen, Xiaojian Liu
doi: 10.1007/s13131-019-1459-z
To determine the grid resolutions of the WRF model in the typhoon simulation, some sensitivity analysis of horizontal and vertical resolutions in different conditions has been carried out. Different horizontal resolutions (5, 10, 20, 30 km), nesting grids (15 and 5 km), different vertical resolutions (35-layers, 28-layers, 20-layers) and different top maximum pressures (1 000, 2 000, 3 500, 5 000 Pa) had been used in the mesoscale numerical model WRF to simulate the Typhoon Kai-tak. The simulation results of typhoon track, wind speed and sea level pressure at different horizontal and vertical resolutions have been compared and analyzed. The horizontal and vertical resolutions of the model have limited effect on the simulation effect of the typhoon track. Different horizontal and vertical resolutions have obvious effects on typhoon strength (defined by wind speed) and intensity (defined by sea level pressure, SLP), especially for sea level pressure. The typhoon intensity simulated by the high-resolution model is closer to the real situation and the nesting grids can improve computational accuracy and efficiency. The simulation results affected by vertical resolution using 35-layers is better than the simulation results using 20-layers and 28-layers simulations. Through comparison and analysis, the horizontal and vertical resolutions of WRF model are finally determined as follows: the two-way nesting grid of 15 and 5 km is comprehensively determined, and the vertical layers is 35-layers, the top maximum pressure is 2 000 Pa.
key words: sensitivity analysis, typhoon track and intensity, horizontal and vertical resolutions, Typhoon Kai-tak, WRF

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