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环境学院发展报告

the growth of snow crystals in clouds where the vapor composition is controlled by the

presence of both ice crystals and water droplets. Modeling of water condensation with the LB
method has the advantage of allowing concentration fields to evolve based on local conditions

so that the controls on grain shapes of the condensed phase can be studied simultaneously
with the controls on isotopic composition and growth rate. Water isotope fractionation d

uring snow crystal growth involves kinetic effects due to diffusion ofwater vapor in air,
which requires careful consideration of the boundary conditions at the ice-vapor interface.

The boundary condition is relatively simple for water isotopes because the molecular
exchange rate for water at the interface is large compared to the crystal growth rate. Our

results for the bulk crystal isotopic composition are consistent with simpler models using
analytical solutions for radial geometry. However, the model results are sufficiently different

for oxygen isotopes that they could affect the interpretation of D-excess values of snow
and ice. The extent of vapor oversaturation plays a major role in determining the water i

sotope fractionation as well as the degree of dendritic growth. Departures from isotopic
equilibrium increase at colder temperatures as diffusivity decreases. Dendritic crystals are

isotopically heterogeneous. Isotopic variations within individual snow crystals could yield
information on the microphysics of ice condensation as well as on the accommodation or

sticking coefficient ofwater associated with vapor deposition. Our results are ultimately a
first step in implementing LB models for kinetically controlled condensation or precipitation

reactions, but needs to be extended also to cases where the molecular exchange rate is
comparable to the crystal growth rate. This approach could also be applicable to aerosol

chemical evolution. (C) 2016 Elsevier Ltd. All rights reserved.
论文链接：https://doi.org/10.1016/j.gca.2015.11.048

8. Effects of inorganic anions on carbon isotope fractionation during Fenton-like
degradation of trichloroethene

作 者：Liu, YD ( 刘运德，博后 )[ 1,2,3 ] ; Zhou, AG ( 周爱国 ) [ 1,2 ] ; Gan, YQ ( 甘义群 )
[ 1,2 ] )[ 1,2 ]
; Li, XQ ( 李小倩
JOURNAL OF HAZARDOUS MATERIALS 卷 :308 页 : 187-191 出 版年 : MAY 5
2016

摘 要：Understanding the magnitude and variability in isotope fractionation with respect to specific
processes is crucial to the application of stable isotopic analysis as a tool to infer and quantify

transformation processes. The variability of carbon isotope fractionation during Fenton-

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